/* HTTP support.
   Copyright (C) 1996-2012, 2014-2015, 2018-2021 Free Software
   Foundation, Inc.

This file is part of GNU Wget.

GNU Wget is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
 (at your option) any later version.

GNU Wget is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Wget.  If not, see <http://www.gnu.org/licenses/>.

Additional permission under GNU GPL version 3 section 7

If you modify this program, or any covered work, by linking or
combining it with the OpenSSL project's OpenSSL library (or a
modified version of that library), containing parts covered by the
terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
grants you additional permission to convey the resulting work.
Corresponding Source for a non-source form of such a combination
shall include the source code for the parts of OpenSSL used as well
as that of the covered work.  */

#include "wget.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <time.h>
#include <locale.h>
#include <fcntl.h>

#include "hash.h"
#include "http.h"
#include "hsts.h"
#include "utils.h"
#include "url.h"
#include "host.h"
#include "retr.h"
#include "connect.h"
#include "netrc.h"
#ifdef HAVE_SSL
# include "ssl.h"
#endif
#ifdef ENABLE_NTLM
# include "http-ntlm.h"
#endif
#include "cookies.h"
#include "md5.h"
#include "convert.h"
#include "spider.h"
#include "warc.h"
#include "c-strcase.h"
#include "version.h"
#include "xstrndup.h"
#ifdef HAVE_METALINK
# include "metalink.h"
#endif
#ifdef ENABLE_XATTR
#include "xattr.h"
#endif

#ifdef TESTING
#include "../tests/unit-tests.h"
#endif

#ifdef __VMS
# include "vms.h"
#endif /* def __VMS */


/* Forward decls. */
struct http_stat;
static char *create_authorization_line (const char *, const char *,
                                        const char *, const char *,
                                        const char *, bool *, uerr_t *);
static char *basic_authentication_encode (const char *, const char *);
static bool known_authentication_scheme_p (const char *, const char *);
static void ensure_extension (struct http_stat *, const char *, int *);
static void load_cookies (void);

static bool cookies_loaded_p;
static struct cookie_jar *wget_cookie_jar;

#define TEXTHTML_S "text/html"
#define TEXTXHTML_S "application/xhtml+xml"
#define TEXTCSS_S "text/css"

/* Some status code validation macros: */
#define H_10X(x)        (((x) >= 100) && ((x) < 200))
#define H_20X(x)        (((x) >= 200) && ((x) < 300))
#define H_PARTIAL(x)    ((x) == HTTP_STATUS_PARTIAL_CONTENTS)
#define H_REDIRECTED(x) ((x) == HTTP_STATUS_MOVED_PERMANENTLY          \
                         || (x) == HTTP_STATUS_MOVED_TEMPORARILY       \
                         || (x) == HTTP_STATUS_SEE_OTHER               \
                         || (x) == HTTP_STATUS_TEMPORARY_REDIRECT      \
                         || (x) == HTTP_STATUS_PERMANENT_REDIRECT)

/* HTTP/1.0 status codes from RFC1945, provided for reference.  */
/* Successful 2xx.  */
#define HTTP_STATUS_OK                    200
#define HTTP_STATUS_CREATED               201
#define HTTP_STATUS_ACCEPTED              202
#define HTTP_STATUS_NO_CONTENT            204
#define HTTP_STATUS_PARTIAL_CONTENTS      206

/* Redirection 3xx.  */
#define HTTP_STATUS_MULTIPLE_CHOICES      300
#define HTTP_STATUS_MOVED_PERMANENTLY     301
#define HTTP_STATUS_MOVED_TEMPORARILY     302
#define HTTP_STATUS_SEE_OTHER             303 /* from HTTP/1.1 */
#define HTTP_STATUS_NOT_MODIFIED          304
#define HTTP_STATUS_TEMPORARY_REDIRECT    307 /* from HTTP/1.1 */
#define HTTP_STATUS_PERMANENT_REDIRECT    308 /* from HTTP/1.1 */

/* Client error 4xx.  */
#define HTTP_STATUS_BAD_REQUEST           400
#define HTTP_STATUS_UNAUTHORIZED          401
#define HTTP_STATUS_FORBIDDEN             403
#define HTTP_STATUS_NOT_FOUND             404
#define HTTP_STATUS_RANGE_NOT_SATISFIABLE 416

/* Server errors 5xx.  */
#define HTTP_STATUS_INTERNAL              500
#define HTTP_STATUS_NOT_IMPLEMENTED       501
#define HTTP_STATUS_BAD_GATEWAY           502
#define HTTP_STATUS_UNAVAILABLE           503
#define HTTP_STATUS_GATEWAY_TIMEOUT       504

enum rp {
  rel_none, rel_name, rel_value, rel_both
};

struct request {
  const char *method;
  char *arg;

  struct request_header {
    char *name, *value;
    enum rp release_policy;
  } *headers;
  int hcount, hcapacity;
};


/* Create a new, empty request. Set the request's method and its
   arguments.  METHOD should be a literal string (or it should outlive
   the request) because it will not be freed.  ARG will be freed by
   request_free.  */

static struct request *
request_new (const char *method, char *arg)
{
  struct request *req = xnew0 (struct request);
  req->hcapacity = 8;
  req->headers = xnew_array (struct request_header, req->hcapacity);
  req->method = method;
  req->arg = arg;
  return req;
}

/* Return the method string passed with the last call to
   request_set_method.  */

static const char *
request_method (const struct request *req)
{
  return req->method;
}

/* Free one header according to the release policy specified with
   request_set_header.  */

static void
release_header (struct request_header *hdr)
{
  switch (hdr->release_policy)
    {
    case rel_none:
      break;
    case rel_name:
      xfree (hdr->name);
      break;
    case rel_value:
      xfree (hdr->value);
      break;
    case rel_both:
      xfree (hdr->name);
      xfree (hdr->value);
      break;
    }
}

/* Set the request named NAME to VALUE.  Specifically, this means that
   a "NAME: VALUE\r\n" header line will be used in the request.  If a
   header with the same name previously existed in the request, its
   value will be replaced by this one.  A NULL value means do nothing.

   RELEASE_POLICY determines whether NAME and VALUE should be released
   (freed) with request_free.  Allowed values are:

    - rel_none     - don't free NAME or VALUE
    - rel_name     - free NAME when done
    - rel_value    - free VALUE when done
    - rel_both     - free both NAME and VALUE when done

   Setting release policy is useful when arguments come from different
   sources.  For example:

     // Don't free literal strings!
     request_set_header (req, "Pragma", "no-cache", rel_none);

     // Don't free a global variable, we'll need it later.
     request_set_header (req, "Referer", opt.referer, rel_none);

     // Value freshly allocated, free it when done.
     request_set_header (req, "Range",
                         aprintf ("bytes=%s-", number_to_static_string (hs->restval)),
                         rel_value);
   */

static void
request_set_header (struct request *req, const char *name, const char *value,
                    enum rp release_policy)
{
  struct request_header *hdr;
  int i;

  if (!value)
    {
      /* A NULL value is a no-op; if freeing the name is requested,
         free it now to avoid leaks.  */
      if (release_policy == rel_name || release_policy == rel_both)
        xfree (name);
      return;
    }

  for (i = 0; i < req->hcount; i++)
    {
      hdr = &req->headers[i];
      if (0 == c_strcasecmp (name, hdr->name))
        {
          /* Replace existing header. */
          release_header (hdr);
          hdr->name = (void *)name;
          hdr->value = (void *)value;
          hdr->release_policy = release_policy;
          return;
        }
    }

  /* Install new header. */

  if (req->hcount >= req->hcapacity)
    {
      req->hcapacity <<= 1;
      req->headers = xrealloc (req->headers, req->hcapacity * sizeof (*hdr));
    }
  hdr = &req->headers[req->hcount++];
  hdr->name = (void *)name;
  hdr->value = (void *)value;
  hdr->release_policy = release_policy;
}

/* Like request_set_header, but sets the whole header line, as
   provided by the user using the `--header' option.  For example,
   request_set_user_header (req, "Foo: bar") works just like
   request_set_header (req, "Foo", "bar").  */

static void
request_set_user_header (struct request *req, const char *header)
{
  const char *name, *p;

  if (!(p = strchr (header, ':')))
    return;

  name = xstrndup(header, p - header);

  ++p;
  while (c_isspace (*p))
    ++p;

  request_set_header (req, name, p, rel_name);
}

/* Remove the header with specified name from REQ.  Returns true if
   the header was actually removed, false otherwise.  */

static bool
request_remove_header (struct request *req, const char *name)
{
  int i;
  for (i = 0; i < req->hcount; i++)
    {
      struct request_header *hdr = &req->headers[i];
      if (0 == c_strcasecmp (name, hdr->name))
        {
          release_header (hdr);
          /* Move the remaining headers by one. */
          if (i < req->hcount - 1)
            memmove (hdr, hdr + 1, (req->hcount - i - 1) * sizeof (*hdr));
          --req->hcount;
          return true;
        }
    }
  return false;
}

#define APPEND(p, str) do {                     \
  int A_len = strlen (str);                     \
  memcpy (p, str, A_len);                       \
  p += A_len;                                   \
} while (0)

/* Construct the request and write it to FD using fd_write.
   If warc_tmp is set to a file pointer, the request string will
   also be written to that file. */

static int
request_send (const struct request *req, int fd, FILE *warc_tmp)
{
  char *request_string, *p;
  int i, size, write_error;

  /* Count the request size. */
  size = 0;

  /* METHOD " " ARG " " "HTTP/1.0" "\r\n" */
  size += strlen (req->method) + 1 + strlen (req->arg) + 1 + 8 + 2;

  for (i = 0; i < req->hcount; i++)
    {
      struct request_header *hdr = &req->headers[i];
      /* NAME ": " VALUE "\r\n" */
      size += strlen (hdr->name) + 2 + strlen (hdr->value) + 2;
    }

  /* "\r\n\0" */
  size += 3;

  p = request_string = xmalloc (size);

  /* Generate the request. */

  APPEND (p, req->method); *p++ = ' ';
  APPEND (p, req->arg);    *p++ = ' ';
  memcpy (p, "HTTP/1.1\r\n", 10); p += 10;

  for (i = 0; i < req->hcount; i++)
    {
      struct request_header *hdr = &req->headers[i];
      APPEND (p, hdr->name);
      *p++ = ':', *p++ = ' ';
      APPEND (p, hdr->value);
      *p++ = '\r', *p++ = '\n';
    }

  *p++ = '\r', *p++ = '\n', *p++ = '\0';
  assert (p - request_string == size);

#undef APPEND

  DEBUGP (("\n---request begin---\n%s---request end---\n", request_string));

  /* Send the request to the server. */

  write_error = fd_write (fd, request_string, size - 1, -1);
  if (write_error < 0)
    logprintf (LOG_VERBOSE, _("Failed writing HTTP request: %s.\n"),
               fd_errstr (fd));
  else if (warc_tmp != NULL)
    {
      /* Write a copy of the data to the WARC record. */
      int warc_tmp_written = fwrite (request_string, 1, size - 1, warc_tmp);
      if (warc_tmp_written != size - 1)
        write_error = -2;
    }
  xfree (request_string);
  return write_error;
}

/* Release the resources used by REQ.
   It is safe to call it with a valid pointer to a NULL pointer.
   It is not safe to call it with an invalid or NULL pointer.  */

static void
request_free (struct request **req_ref)
{
  int i;
  struct request *req = *req_ref;

  if (!req)
    return;

  xfree (req->arg);
  for (i = 0; i < req->hcount; i++)
    release_header (&req->headers[i]);
  xfree (req->headers);
  xfree (req);
  *req_ref = NULL;
}

static struct hash_table *basic_authed_hosts;

/* Find out if this host has issued a Basic challenge yet; if so, give
 * it the username, password. A temporary measure until we can get
 * proper authentication in place. */

static bool
maybe_send_basic_creds (const char *hostname, const char *user,
                        const char *passwd, struct request *req)
{
  bool do_challenge = false;

  if (opt.auth_without_challenge)
    {
      DEBUGP (("Auth-without-challenge set, sending Basic credentials.\n"));
      do_challenge = true;
    }
  else if (basic_authed_hosts
      && hash_table_contains (basic_authed_hosts, hostname))
    {
      DEBUGP (("Found %s in basic_authed_hosts.\n", quote (hostname)));
      do_challenge = true;
    }
  else
    {
      DEBUGP (("Host %s has not issued a general basic challenge.\n",
              quote (hostname)));
    }
  if (do_challenge)
    {
      request_set_header (req, "Authorization",
                          basic_authentication_encode (user, passwd),
                          rel_value);
    }
  return do_challenge;
}

static void
register_basic_auth_host (const char *hostname)
{
  if (!basic_authed_hosts)
    {
      basic_authed_hosts = make_nocase_string_hash_table (1);
    }
  if (!hash_table_contains (basic_authed_hosts, hostname))
    {
      hash_table_put (basic_authed_hosts, xstrdup (hostname), NULL);
      DEBUGP (("Inserted %s into basic_authed_hosts\n", quote (hostname)));
    }
}

/* Send the contents of FILE_NAME to SOCK.  Make sure that exactly
   PROMISED_SIZE bytes are sent over the wire -- if the file is
   longer, read only that much; if the file is shorter, report an error.
   If warc_tmp is set to a file pointer, the post data will
   also be written to that file.  */

static int
body_file_send (int sock, const char *file_name, wgint promised_size, FILE *warc_tmp)
{
  static char chunk[8192];
  wgint written = 0;
  int write_error;
  FILE *fp;

  DEBUGP (("[writing BODY file %s ... ", file_name));

  fp = fopen (file_name, "rb");
  if (!fp)
    return -1;
  while (!feof (fp) && written < promised_size)
    {
      int towrite;
      int length = fread (chunk, 1, sizeof (chunk), fp);
      if (length == 0)
        break;
      towrite = MIN (promised_size - written, length);
      write_error = fd_write (sock, chunk, towrite, -1);
      if (write_error < 0)
        {
          fclose (fp);
          return -1;
        }
      if (warc_tmp != NULL)
        {
          /* Write a copy of the data to the WARC record. */
          int warc_tmp_written = fwrite (chunk, 1, towrite, warc_tmp);
          if (warc_tmp_written != towrite)
            {
              fclose (fp);
              return -2;
            }
        }
      written += towrite;
    }
  fclose (fp);

  /* If we've written less than was promised, report a (probably
     nonsensical) error rather than break the promise.  */
  if (written < promised_size)
    {
      errno = EINVAL;
      return -1;
    }

  assert (written == promised_size);
  DEBUGP (("done]\n"));
  return 0;
}

/* Determine whether [START, PEEKED + PEEKLEN) contains an empty line.
   If so, return the pointer to the position after the line, otherwise
   return NULL.  This is used as callback to fd_read_hunk.  The data
   between START and PEEKED has been read and cannot be "unread"; the
   data after PEEKED has only been peeked.  */

static const char *
response_head_terminator (const char *start, const char *peeked, int peeklen)
{
  const char *p, *end;

  /* If at first peek, verify whether HUNK starts with "HTTP".  If
     not, this is a HTTP/0.9 request and we must bail out without
     reading anything.  */
  if (start == peeked && 0 != memcmp (start, "HTTP", MIN (peeklen, 4)))
    return start;

  /* Look for "\n[\r]\n", and return the following position if found.
     Start two chars before the current to cover the possibility that
     part of the terminator (e.g. "\n\r") arrived in the previous
     batch.  */
  p = peeked - start < 2 ? start : peeked - 2;
  end = peeked + peeklen;

  /* Check for \n\r\n or \n\n anywhere in [p, end-2). */
  for (; p < end - 2; p++)
    if (*p == '\n')
      {
        if (p[1] == '\r' && p[2] == '\n')
          return p + 3;
        else if (p[1] == '\n')
          return p + 2;
      }
  /* p==end-2: check for \n\n directly preceding END. */
  if (peeklen >= 2 && p[0] == '\n' && p[1] == '\n')
    return p + 2;

  return NULL;
}

/* The maximum size of a single HTTP response we care to read.  Rather
   than being a limit of the reader implementation, this limit
   prevents Wget from slurping all available memory upon encountering
   malicious or buggy server output, thus protecting the user.  Define
   it to 0 to remove the limit.  */

#define HTTP_RESPONSE_MAX_SIZE 65536

/* Read the HTTP request head from FD and return it.  The error
   conditions are the same as with fd_read_hunk.

   To support HTTP/0.9 responses, this function tries to make sure
   that the data begins with "HTTP".  If this is not the case, no data
   is read and an empty request is returned, so that the remaining
   data can be treated as body.  */

static char *
read_http_response_head (int fd)
{
  return fd_read_hunk (fd, response_head_terminator, 512,
                       HTTP_RESPONSE_MAX_SIZE);
}

struct response {
  /* The response data. */
  const char *data;

  /* The array of pointers that indicate where each header starts.
     For example, given this HTTP response:

       HTTP/1.0 200 Ok
       Description: some
        text
       Etag: x

     The headers are located like this:

     "HTTP/1.0 200 Ok\r\nDescription: some\r\n text\r\nEtag: x\r\n\r\n"
     ^                   ^                             ^          ^
     headers[0]          headers[1]                    headers[2] headers[3]

     I.e. headers[0] points to the beginning of the request,
     headers[1] points to the end of the first header and the
     beginning of the second one, etc.  */

  const char **headers;
};

/* Create a new response object from the text of the HTTP response,
   available in HEAD.  That text is automatically split into
   constituent header lines for fast retrieval using
   resp_header_*.  */

static struct response *
resp_new (char *head)
{
  char *hdr;
  int count, size;

  struct response *resp = xnew0 (struct response);
  resp->data = head;

  if (*head == '\0')
    {
      /* Empty head means that we're dealing with a headerless
         (HTTP/0.9) response.  In that case, don't set HEADERS at
         all.  */
      return resp;
    }

  /* Split HEAD into header lines, so that resp_header_* functions
     don't need to do this over and over again.  */

  size = count = 0;
  hdr = head;
  while (1)
    {
      DO_REALLOC (resp->headers, size, count + 1, const char *);
      resp->headers[count++] = hdr;

      /* Break upon encountering an empty line. */
      if (!hdr[0] || (hdr[0] == '\r' && hdr[1] == '\n') || hdr[0] == '\n')
        break;

      /* Find the end of HDR, including continuations. */
      for (;;)
        {
          char *end = strchr (hdr, '\n');

          if (!end)
            {
              hdr += strlen (hdr);
              break;
            }

          hdr = end + 1;

          if (*hdr != ' ' && *hdr != '\t')
            break;

          // continuation, transform \r and \n into spaces
          *end = ' ';
          if (end > head && end[-1] == '\r')
            end[-1] = ' ';
        }
    }
  DO_REALLOC (resp->headers, size, count + 1, const char *);
  resp->headers[count] = NULL;

  return resp;
}

/* Locate the header named NAME in the request data, starting with
   position START.  This allows the code to loop through the request
   data, filtering for all requests of a given name.  Returns the
   found position, or -1 for failure.  The code that uses this
   function typically looks like this:

     for (pos = 0; (pos = resp_header_locate (...)) != -1; pos++)
       ... do something with header ...

   If you only care about one header, use resp_header_get instead of
   this function.  */

static int
resp_header_locate (const struct response *resp, const char *name, int start,
                    const char **begptr, const char **endptr)
{
  int i;
  const char **headers = resp->headers;
  int name_len;

  if (!headers || !headers[1])
    return -1;

  name_len = strlen (name);
  if (start > 0)
    i = start;
  else
    i = 1;

  for (; headers[i + 1]; i++)
    {
      const char *b = headers[i];
      const char *e = headers[i + 1];
      if (e - b > name_len
          && b[name_len] == ':'
          && 0 == c_strncasecmp (b, name, name_len))
        {
          b += name_len + 1;
          while (b < e && c_isspace (*b))
            ++b;
          while (b < e && c_isspace (e[-1]))
            --e;
          *begptr = b;
          *endptr = e;
          return i;
        }
    }
  return -1;
}

/* Find and retrieve the header named NAME in the request data.  If
   found, set *BEGPTR to its starting, and *ENDPTR to its ending
   position, and return true.  Otherwise return false.

   This function is used as a building block for resp_header_copy
   and resp_header_strdup.  */

static bool
resp_header_get (const struct response *resp, const char *name,
                 const char **begptr, const char **endptr)
{
  int pos = resp_header_locate (resp, name, 0, begptr, endptr);
  return pos != -1;
}

/* Copy the response header named NAME to buffer BUF, no longer than
   BUFSIZE (BUFSIZE includes the terminating 0).  If the header
   exists, true is returned, false otherwise.  If there should be no
   limit on the size of the header, use resp_header_strdup instead.

   If BUFSIZE is 0, no data is copied, but the boolean indication of
   whether the header is present is still returned.  */

static bool
resp_header_copy (const struct response *resp, const char *name,
                  char *buf, int bufsize)
{
  const char *b, *e;
  if (!resp_header_get (resp, name, &b, &e))
    return false;
  if (bufsize)
    {
      int len = MIN (e - b, bufsize - 1);
      memcpy (buf, b, len);
      buf[len] = '\0';
    }
  return true;
}

/* Return the value of header named NAME in RESP, allocated with
   malloc.  If such a header does not exist in RESP, return NULL.  */

static char *
resp_header_strdup (const struct response *resp, const char *name)
{
  const char *b, *e;
  if (!resp_header_get (resp, name, &b, &e))
    return NULL;
  return strdupdelim (b, e);
}

/* Parse the HTTP status line, which is of format:

   HTTP-Version SP Status-Code SP Reason-Phrase

   The function returns the status-code, or -1 if the status line
   appears malformed.  The pointer to "reason-phrase" message is
   returned in *MESSAGE.  */

static int
resp_status (const struct response *resp, char **message)
{
  int status;
  const char *p, *end;

  if (!resp->headers)
    {
      /* For a HTTP/0.9 response, assume status 200. */
      if (message)
        *message = xstrdup (_("No headers, assuming HTTP/0.9"));
      return 200;
    }

  p = resp->headers[0];
  end = resp->headers[1];

  if (!end)
    return -1;

  /* "HTTP" */
  if (end - p < 4 || 0 != strncmp (p, "HTTP", 4))
    return -1;
  p += 4;

  /* Match the HTTP version.  This is optional because Gnutella
     servers have been reported to not specify HTTP version.  */
  if (p < end && *p == '/')
    {
      ++p;
      while (p < end && c_isdigit (*p))
        ++p;
      if (p < end && *p == '.')
        ++p;
      while (p < end && c_isdigit (*p))
        ++p;
    }

  while (p < end && c_isspace (*p))
    ++p;
  if (end - p < 3 || !c_isdigit (p[0]) || !c_isdigit (p[1]) || !c_isdigit (p[2]))
    return -1;

  status = 100 * (p[0] - '0') + 10 * (p[1] - '0') + (p[2] - '0');
  p += 3;

  if (message)
    {
      while (p < end && c_isspace (*p))
        ++p;
      while (p < end && c_isspace (end[-1]))
        --end;
      *message = strdupdelim (p, end);
    }

  return status;
}

/* Release the resources used by RESP.
   It is safe to call it with a valid pointer to a NULL pointer.
   It is not safe to call it with a invalid or NULL pointer.  */

static void
resp_free (struct response **resp_ref)
{
  struct response *resp = *resp_ref;

  if (!resp)
    return;

  xfree (resp->headers);
  xfree (resp);

  *resp_ref = NULL;
}

/* Print a single line of response, the characters [b, e).  We tried
   getting away with
      logprintf (LOG_VERBOSE, "%s%.*s\n", prefix, (int) (e - b), b);
   but that failed to escape the non-printable characters and, in fact,
   caused crashes in UTF-8 locales.  */

static void
print_response_line (const char *prefix, const char *b, const char *e)
{
  char buf[1024], *copy;
  size_t len = e - b;

  if (len < sizeof (buf))
    copy = buf;
  else
    copy = xmalloc(len + 1);

  memcpy(copy, b, len);
  copy[len] = 0;

  logprintf (LOG_ALWAYS, "%s%s\n", prefix,
             quotearg_style (escape_quoting_style, copy));

  if (copy != buf)
    xfree (copy);
}

/* Print the server response, line by line, omitting the trailing CRLF
   from individual header lines, and prefixed with PREFIX.  */

static void
print_server_response (const struct response *resp, const char *prefix)
{
  int i;
  if (!resp->headers)
    return;
  for (i = 0; resp->headers[i + 1]; i++)
    {
      const char *b = resp->headers[i];
      const char *e = resp->headers[i + 1];
      /* Skip CRLF */
      if (b < e && e[-1] == '\n')
        --e;
      if (b < e && e[-1] == '\r')
        --e;
      print_response_line (prefix, b, e);
    }
}

/* Parse the `Content-Range' header and extract the information it
   contains.  Returns true if successful, false otherwise.  */
static bool
parse_content_range (const char *hdr, wgint *first_byte_ptr,
                     wgint *last_byte_ptr, wgint *entity_length_ptr)
{
  wgint num;

  /* Ancient versions of Netscape proxy server, presumably predating
     rfc2068, sent out `Content-Range' without the "bytes"
     specifier.  */
  if (0 == strncasecmp (hdr, "bytes", 5))
    {
      hdr += 5;
      /* "JavaWebServer/1.1.1" sends "bytes: x-y/z", contrary to the
         HTTP spec. */
      if (*hdr == ':')
        ++hdr;
      while (c_isspace (*hdr))
        ++hdr;
      if (!*hdr)
        return false;
    }
  if (!c_isdigit (*hdr))
    return false;
  for (num = 0; c_isdigit (*hdr); hdr++)
    num = 10 * num + (*hdr - '0');
  if (*hdr != '-' || !c_isdigit (*(hdr + 1)))
    return false;
  *first_byte_ptr = num;
  ++hdr;
  for (num = 0; c_isdigit (*hdr); hdr++)
    num = 10 * num + (*hdr - '0');
  if (*hdr != '/')
    return false;
  *last_byte_ptr = num;
  if (!(c_isdigit (*(hdr + 1)) || *(hdr + 1) == '*'))
    return false;
  if (*last_byte_ptr < *first_byte_ptr)
    return false;
  ++hdr;
  if (*hdr == '*')
    num = -1;
  else
    for (num = 0; c_isdigit (*hdr); hdr++)
      num = 10 * num + (*hdr - '0');
  *entity_length_ptr = num;
  if ((*entity_length_ptr <= *last_byte_ptr) && *entity_length_ptr != -1)
    return false;
  return true;
}

/* Read the body of the request, but don't store it anywhere and don't
   display a progress gauge.  This is useful for reading the bodies of
   administrative responses to which we will soon issue another
   request.  The response is not useful to the user, but reading it
   allows us to continue using the same connection to the server.

   If reading fails, false is returned, true otherwise.  In debug
   mode, the body is displayed for debugging purposes.  */

static bool
skip_short_body (int fd, wgint contlen, bool chunked)
{
  enum {
    SKIP_SIZE = 512,                /* size of the download buffer */
    SKIP_THRESHOLD = 4096        /* the largest size we read */
  };
  wgint remaining_chunk_size = 0;
  char dlbuf[SKIP_SIZE + 1];
  dlbuf[SKIP_SIZE] = '\0';        /* so DEBUGP can safely print it */

  /* If the body is too large, it makes more sense to simply close the
     connection than to try to read the body.  */
  if (contlen > SKIP_THRESHOLD)
    return false;

  while (contlen > 0 || chunked)
    {
      int ret;
      if (chunked)
        {
          if (remaining_chunk_size == 0)
            {
              char *line = fd_read_line (fd);
              char *endl;
              if (line == NULL)
                break;

              remaining_chunk_size = strtol (line, &endl, 16);
              xfree (line);

              if (remaining_chunk_size < 0)
                return false;

              if (remaining_chunk_size == 0)
                {
                  line = fd_read_line (fd);
                  xfree (line);
                  break;
                }
            }

          contlen = MIN (remaining_chunk_size, SKIP_SIZE);
        }

      DEBUGP (("Skipping %s bytes of body: [", number_to_static_string (contlen)));

      ret = fd_read (fd, dlbuf, MIN (contlen, SKIP_SIZE), -1);
      if (ret <= 0)
        {
          /* Don't normally report the error since this is an
             optimization that should be invisible to the user.  */
          DEBUGP (("] aborting (%s).\n",
                   ret < 0 ? fd_errstr (fd) : "EOF received"));
          return false;
        }
      contlen -= ret;

      if (chunked)
        {
          remaining_chunk_size -= ret;
          if (remaining_chunk_size == 0)
            {
              char *line = fd_read_line (fd);
              if (line == NULL)
                return false;
              else
                xfree (line);
            }
        }

      /* Safe even if %.*s bogusly expects terminating \0 because
         we've zero-terminated dlbuf above.  */
      DEBUGP (("%.*s", ret, dlbuf));
    }

  DEBUGP (("] done.\n"));
  return true;
}

#define NOT_RFC2231 0
#define RFC2231_NOENCODING 1
#define RFC2231_ENCODING 2

/* extract_param extracts the parameter name into NAME.
   However, if the parameter name is in RFC2231 format then
   this function adjusts NAME by stripping of the trailing
   characters that are not part of the name but are present to
   indicate the presence of encoding information in the value
   or a fragment of a long parameter value
*/
static int
modify_param_name (param_token *name)
{
  const char *delim1 = memchr (name->b, '*', name->e - name->b);
  const char *delim2 = memrchr (name->b, '*', name->e - name->b);

  int result;

  if (delim1 == NULL)
    {
      result = NOT_RFC2231;
    }
  else if (delim1 == delim2)
    {
      if ((name->e - 1) == delim1)
        {
          result = RFC2231_ENCODING;
        }
      else
        {
          result = RFC2231_NOENCODING;
        }
      name->e = delim1;
    }
  else
    {
      name->e = delim1;
      result = RFC2231_ENCODING;
    }
  return result;
}

/* extract_param extract the parameter value into VALUE.
   Like modify_param_name this function modifies VALUE by
   stripping off the encoding information from the actual value
*/
static void
modify_param_value (param_token *value, int encoding_type )
{
  if (encoding_type == RFC2231_ENCODING)
    {
      const char *delim = memrchr (value->b, '\'', value->e - value->b);
      if (delim != NULL)
        {
          value->b = (delim+1);
        }
    }
}

/* Extract a parameter from the string (typically an HTTP header) at
   **SOURCE and advance SOURCE to the next parameter.  Return false
   when there are no more parameters to extract.  The name of the
   parameter is returned in NAME, and the value in VALUE.  If the
   parameter has no value, the token's value is zeroed out.

   For example, if *SOURCE points to the string "attachment;
   filename=\"foo bar\"", the first call to this function will return
   the token named "attachment" and no value, and the second call will
   return the token named "filename" and value "foo bar".  The third
   call will return false, indicating no more valid tokens.

   is_url_encoded is an out parameter. If not NULL, a boolean value will be
   stored into it, letting the caller know whether or not the extracted value is
   URL-encoded. The caller can then decode it with url_unescape(), which however
   performs decoding in-place. URL-encoding is used by RFC 2231 to support
   non-US-ASCII characters in HTTP header values.  */

bool
extract_param (const char **source, param_token *name, param_token *value,
               char separator, bool *is_url_encoded)
{
  const char *p = *source;
  int param_type;
  if (is_url_encoded)
    *is_url_encoded = false;   /* initializing the out parameter */

  while (c_isspace (*p)) ++p;
  if (!*p)
    {
      *source = p;
      return false;             /* no error; nothing more to extract */
    }

  /* Extract name. */
  name->b = p;
  while (*p && !c_isspace (*p) && *p != '=' && *p != separator) ++p;
  name->e = p;
  if (name->b == name->e)
    return false;               /* empty name: error */
  while (c_isspace (*p)) ++p;
  if (*p == separator || !*p)           /* no value */
    {
      xzero (*value);
      if (*p == separator) ++p;
      *source = p;
      return true;
    }
  if (*p != '=')
    return false;               /* error */

  /* *p is '=', extract value */
  ++p;
  while (c_isspace (*p)) ++p;
  if (*p == '"')                /* quoted */
    {
      value->b = ++p;
      while (*p && *p != '"') ++p;
      if (!*p)
        return false;
      value->e = p++;
      /* Currently at closing quote; find the end of param. */
      while (c_isspace (*p)) ++p;
      while (*p && *p != separator) ++p;
      if (*p == separator)
        ++p;
      else if (*p)
        /* garbage after closed quote, e.g. foo="bar"baz */
        return false;
    }
  else                          /* unquoted */
    {
      value->b = p;
      while (*p && *p != separator) ++p;
      value->e = p;
      while (value->e != value->b && c_isspace (value->e[-1]))
        --value->e;
      if (*p == separator) ++p;
    }
  *source = p;

  param_type = modify_param_name (name);
  if (param_type != NOT_RFC2231)
    {
      if (param_type == RFC2231_ENCODING && is_url_encoded)
        *is_url_encoded = true;
      modify_param_value (value, param_type);
    }
  return true;
}

#undef NOT_RFC2231
#undef RFC2231_NOENCODING
#undef RFC2231_ENCODING

/* Appends the string represented by VALUE to FILENAME */

static void
append_value_to_filename (char **filename, param_token const * const value,
                          bool is_url_encoded)
{
  int original_length = strlen (*filename);
  int new_length = strlen (*filename) + (value->e - value->b);
  *filename = xrealloc (*filename, new_length+1);
  memcpy (*filename + original_length, value->b, (value->e - value->b));
  (*filename)[new_length] = '\0';
  if (is_url_encoded)
    url_unescape (*filename + original_length);
}

/* Parse the contents of the `Content-Disposition' header, extracting
   the information useful to Wget.  Content-Disposition is a header
   borrowed from MIME; when used in HTTP, it typically serves for
   specifying the desired file name of the resource.  For example:

       Content-Disposition: attachment; filename="flora.jpg"

   Wget will skip the tokens it doesn't care about, such as
   "attachment" in the previous example; it will also skip other
   unrecognized params.  If the header is syntactically correct and
   contains a file name, a copy of the file name is stored in
   *filename and true is returned.  Otherwise, the function returns
   false.

   The file name is stripped of directory components and must not be
   empty.

   Historically, this function returned filename prefixed with opt.dir_prefix,
   now that logic is handled by the caller, new code should pay attention,
   changed by crq, Sep 2010.

*/
static bool
parse_content_disposition (const char *hdr, char **filename)
{
  param_token name, value;
  bool is_url_encoded = false;

  char *encodedFilename = NULL;
  char *unencodedFilename = NULL;
  for ( ; extract_param (&hdr, &name, &value, ';', &is_url_encoded);
        is_url_encoded = false)
    {
      int isFilename = BOUNDED_EQUAL_NO_CASE (name.b, name.e, "filename");
      if ( isFilename && value.b != NULL)
        {
          /* Make the file name begin at the last slash or backslash. */
          bool isEncodedFilename;
          char **outFilename;
          const char *last_slash = memrchr (value.b, '/', value.e - value.b);
          const char *last_bs = memrchr (value.b, '\\', value.e - value.b);
          if (last_slash && last_bs)
            value.b = 1 + MAX (last_slash, last_bs);
          else if (last_slash || last_bs)
            value.b = 1 + (last_slash ? last_slash : last_bs);
          if (value.b == value.e)
            continue;

          /* Check if the name is "filename*" as specified in RFC 6266.
           * Since "filename" could be broken up as "filename*N" (RFC 2231),
           * a check is needed to make sure this is not the case */
          isEncodedFilename = *name.e == '*' && !c_isdigit (*(name.e + 1));
          outFilename = isEncodedFilename ? &encodedFilename
            : &unencodedFilename;
          if (*outFilename)
            append_value_to_filename (outFilename, &value, is_url_encoded);
          else
            {
              *outFilename = strdupdelim (value.b, value.e);
              if (is_url_encoded)
                url_unescape (*outFilename);
            }
        }
    }
  if (encodedFilename)
    {
      xfree (unencodedFilename);
      *filename = encodedFilename;
    }
  else
    {
      xfree (encodedFilename);
      *filename = unencodedFilename;
    }
  if (*filename)
    return true;
  else
    return false;
}

#ifdef HAVE_HSTS
static bool
parse_strict_transport_security (const char *header, time_t *max_age, bool *include_subdomains)
{
  param_token name, value;
  const char *c_max_age = NULL;
  bool is = false; /* includeSubDomains */
  bool is_url_encoded = false;
  bool success = false;

  if (header)
    {
      /* Process the STS header. Keys should be matched case-insensitively. */
      for (; extract_param (&header, &name, &value, ';', &is_url_encoded); is_url_encoded = false)
        {
          if (BOUNDED_EQUAL_NO_CASE (name.b, name.e, "max-age"))
            {
              xfree (c_max_age);
              c_max_age = strdupdelim (value.b, value.e);
            }
          else if (BOUNDED_EQUAL_NO_CASE (name.b, name.e, "includeSubDomains"))
            is = true;
        }

      /* pass the parsed values over */
      if (c_max_age)
        {
          /* If the string value goes out of a long's bounds, strtol() will return LONG_MIN or LONG_MAX.
           * In theory, the HSTS engine should be able to handle it.
           * Also, time_t is normally defined as a long, so this should not break.
           */
          if (max_age)
            *max_age = (time_t) strtol (c_max_age, NULL, 10);
          if (include_subdomains)
            *include_subdomains = is;

          DEBUGP (("Parsed Strict-Transport-Security max-age = %s, includeSubDomains = %s\n",
                 c_max_age, (is ? "true" : "false")));

          xfree (c_max_age);
          success = true;
        }
      else
        {
          /* something weird happened */
          logprintf (LOG_VERBOSE, "Could not parse String-Transport-Security header\n");
          success = false;
        }
    }

  return success;
}
#endif

/* Persistent connections.  Currently, we cache the most recently used
   connection as persistent, provided that the HTTP server agrees to
   make it such.  The persistence data is stored in the variables
   below.  Ideally, it should be possible to cache an arbitrary fixed
   number of these connections.  */

/* Whether a persistent connection is active. */
static bool pconn_active;

static struct {
  /* The socket of the connection.  */
  int socket;

  /* Host and port of the currently active persistent connection. */
  char *host;
  int port;

  /* Whether a ssl handshake has occurred on this connection.  */
  bool ssl;

  /* Whether the connection was authorized.  This is only done by
     NTLM, which authorizes *connections* rather than individual
     requests.  (That practice is peculiar for HTTP, but it is a
     useful optimization.)  */
  bool authorized;

#ifdef ENABLE_NTLM
  /* NTLM data of the current connection.  */
  struct ntlmdata ntlm;
#endif
} pconn;

/* Mark the persistent connection as invalid and free the resources it
   uses.  This is used by the CLOSE_* macros after they forcefully
   close a registered persistent connection.  */

static void
invalidate_persistent (void)
{
  DEBUGP (("Disabling further reuse of socket %d.\n", pconn.socket));
  pconn_active = false;
  fd_close (pconn.socket);
  xfree (pconn.host);
  xzero (pconn);
}

/* Register FD, which should be a TCP/IP connection to HOST:PORT, as
   persistent.  This will enable someone to use the same connection
   later.  In the context of HTTP, this must be called only AFTER the
   response has been received and the server has promised that the
   connection will remain alive.

   If a previous connection was persistent, it is closed. */

static void
register_persistent (const char *host, int port, int fd, bool ssl)
{
  if (pconn_active)
    {
      if (pconn.socket == fd)
        {
          /* The connection FD is already registered. */
          return;
        }
      else
        {
          /* The old persistent connection is still active; close it
             first.  This situation arises whenever a persistent
             connection exists, but we then connect to a different
             host, and try to register a persistent connection to that
             one.  */
          invalidate_persistent ();
        }
    }

  pconn_active = true;
  pconn.socket = fd;
  pconn.host = xstrdup (host);
  pconn.port = port;
  pconn.ssl = ssl;
  pconn.authorized = false;

  DEBUGP (("Registered socket %d for persistent reuse.\n", fd));
}

/* Return true if a persistent connection is available for connecting
   to HOST:PORT.  */

static bool
persistent_available_p (const char *host, int port, bool ssl,
                        bool *host_lookup_failed)
{
  /* First, check whether a persistent connection is active at all.  */
  if (!pconn_active)
    return false;

  /* If we want SSL and the last connection wasn't or vice versa,
     don't use it.  Checking for host and port is not enough because
     HTTP and HTTPS can apparently coexist on the same port.  */
  if (ssl != pconn.ssl)
    return false;

  /* If we're not connecting to the same port, we're not interested. */
  if (port != pconn.port)
    return false;

  /* If the host is the same, we're in business.  If not, there is
     still hope -- read below.  */
  if (0 != strcasecmp (host, pconn.host))
    {
      /* Check if pconn.socket is talking to HOST under another name.
         This happens often when both sites are virtual hosts
         distinguished only by name and served by the same network
         interface, and hence the same web server (possibly set up by
         the ISP and serving many different web sites).  This
         admittedly unconventional optimization does not contradict
         HTTP and works well with popular server software.  */

      bool found;
      ip_address ip;
      struct address_list *al;

      if (ssl)
        /* Don't try to talk to two different SSL sites over the same
           secure connection!  (Besides, it's not clear that
           name-based virtual hosting is even possible with SSL.)  */
        return false;

      /* If pconn.socket's peer is one of the IP addresses HOST
         resolves to, pconn.socket is for all intents and purposes
         already talking to HOST.  */

      if (!socket_ip_address (pconn.socket, &ip, ENDPOINT_PEER))
        {
          /* Can't get the peer's address -- something must be very
             wrong with the connection.  */
          invalidate_persistent ();
          return false;
        }
      al = lookup_host (host, 0);
      if (!al)
        {
          *host_lookup_failed = true;
          return false;
        }

      found = address_list_contains (al, &ip);
      address_list_release (al);

      if (!found)
        return false;

      /* The persistent connection's peer address was found among the
         addresses HOST resolved to; therefore, pconn.sock is in fact
         already talking to HOST -- no need to reconnect.  */
    }

  /* Finally, check whether the connection is still open.  This is
     important because most servers implement liberal (short) timeout
     on persistent connections.  Wget can of course always reconnect
     if the connection doesn't work out, but it's nicer to know in
     advance.  This test is a logical followup of the first test, but
     is "expensive" and therefore placed at the end of the list.

     (Current implementation of test_socket_open has a nice side
     effect that it treats sockets with pending data as "closed".
     This is exactly what we want: if a broken server sends message
     body in response to HEAD, or if it sends more than conent-length
     data, we won't reuse the corrupted connection.)  */

  if (!test_socket_open (pconn.socket))
    {
      /* Oops, the socket is no longer open.  Now that we know that,
         let's invalidate the persistent connection before returning
         0.  */
      invalidate_persistent ();
      return false;
    }

  return true;
}

/* The idea behind these two CLOSE macros is to distinguish between
   two cases: one when the job we've been doing is finished, and we
   want to close the connection and leave, and two when something is
   seriously wrong and we're closing the connection as part of
   cleanup.

   In case of keep_alive, CLOSE_FINISH should leave the connection
   open, while CLOSE_INVALIDATE should still close it.

   Note that the semantics of the flag `keep_alive' is "this
   connection *will* be reused (the server has promised not to close
   the connection once we're done)", while the semantics of
   `pc_active_p && (fd) == pc_last_fd' is "we're *now* using an
   active, registered connection".  */

#define CLOSE_FINISH(fd) do {                   \
  if (!keep_alive)                              \
    {                                           \
      if (pconn_active && (fd) == pconn.socket) \
        invalidate_persistent ();               \
      else                                      \
          fd_close (fd);                        \
      fd = -1;                                  \
    }                                           \
} while (0)

#define CLOSE_INVALIDATE(fd) do {               \
  if (pconn_active && (fd) == pconn.socket)     \
    invalidate_persistent ();                   \
  else                                          \
    fd_close (fd);                              \
  fd = -1;                                      \
} while (0)

typedef enum
{
  ENC_INVALID = -1,             /* invalid encoding */
  ENC_NONE = 0,                 /* no special encoding */
  ENC_GZIP,                     /* gzip compression */
  ENC_DEFLATE,                  /* deflate compression */
  ENC_COMPRESS,                 /* compress compression */
  ENC_BROTLI                    /* brotli compression */
} encoding_t;

struct http_stat
{
  wgint len;                    /* received length */
  wgint contlen;                /* expected length */
  wgint restval;                /* the restart value */
  int res;                      /* the result of last read */
  char *rderrmsg;               /* error message from read error */
  char *newloc;                 /* new location (redirection) */
  char *remote_time;            /* remote time-stamp string */
  char *error;                  /* textual HTTP error */
  int statcode;                 /* status code */
  char *message;                /* status message */
  wgint rd_size;                /* amount of data read from socket */
  double dltime;                /* time it took to download the data */
  const char *referer;          /* value of the referer header. */
  char *local_file;             /* local file name. */
  bool existence_checked;       /* true if we already checked for a file's
                                   existence after having begun to download
                                   (needed in gethttp for when connection is
                                   interrupted/restarted. */
  bool timestamp_checked;       /* true if pre-download time-stamping checks
                                 * have already been performed */
  char *orig_file_name;         /* name of file to compare for time-stamping
                                 * (might be != local_file if -K is set) */
  wgint orig_file_size;         /* size of file to compare for time-stamping */
  time_t orig_file_tstamp;      /* time-stamp of file to compare for
                                 * time-stamping */
#ifdef HAVE_METALINK
  metalink_t *metalink;
#endif

  encoding_t local_encoding;    /* the encoding of the local file */
  encoding_t remote_encoding;   /* the encoding of the remote file */

  bool temporary;               /* downloading a temporary file */
};

static void
free_hstat (struct http_stat *hs)
{
  xfree (hs->newloc);
  xfree (hs->remote_time);
  xfree (hs->error);
  xfree (hs->rderrmsg);
  xfree (hs->local_file);
  xfree (hs->orig_file_name);
  xfree (hs->message);
#ifdef HAVE_METALINK
  metalink_delete (hs->metalink);
  hs->metalink = NULL;
#endif
}

static void
get_file_flags (const char *filename, int *dt)
{
  logprintf (LOG_VERBOSE, _("\
File %s already there; not retrieving.\n\n"), quote (filename));
  /* If the file is there, we suppose it's retrieved OK.  */
  *dt |= RETROKF;

  /* #### Bogusness alert.  */
  /* If its suffix is "html" or "htm" or similar, assume text/html.  */
  if (has_html_suffix_p (filename))
    *dt |= TEXTHTML;
}

/* Download the response body from the socket and writes it to
   an output file.  The headers have already been read from the
   socket.  If WARC is enabled, the response body will also be
   written to a WARC response record.

   hs, contlen, contrange, chunked_transfer_encoding and url are
   parameters from the gethttp method.  fp is a pointer to the
   output file.

   url, warc_timestamp_str, warc_request_uuid, warc_ip, type
   and statcode will be saved in the headers of the WARC record.
   The head parameter contains the HTTP headers of the response.

   If fp is NULL and WARC is enabled, the response body will be
   written only to the WARC file.  If WARC is disabled and fp
   is a file pointer, the data will be written to the file.
   If fp is a file pointer and WARC is enabled, the body will
   be written to both destinations.

   Returns the error code.   */
static int
read_response_body (struct http_stat *hs, int sock, FILE *fp, wgint contlen,
                    wgint contrange, bool chunked_transfer_encoding,
                    char *url, char *warc_timestamp_str, char *warc_request_uuid,
                    ip_address *warc_ip, char *type, int statcode, char *head)
{
  int warc_payload_offset = 0;
  FILE *warc_tmp = NULL;
  int warcerr = 0;
  int flags = 0;

  if (opt.warc_filename != NULL)
    {
      /* Open a temporary file where we can write the response before we
         add it to the WARC record.  */
      warc_tmp = warc_tempfile ();
      if (warc_tmp == NULL)
        warcerr = WARC_TMP_FOPENERR;

      if (warcerr == 0)
        {
          /* We should keep the response headers for the WARC record.  */
          int head_len = strlen (head);
          int warc_tmp_written = fwrite (head, 1, head_len, warc_tmp);
          if (warc_tmp_written != head_len)
            warcerr = WARC_TMP_FWRITEERR;
          warc_payload_offset = head_len;
        }

      if (warcerr != 0)
        {
          if (warc_tmp != NULL)
            fclose (warc_tmp);
          return warcerr;
        }
    }

  if (fp != NULL)
    {
      /* This confuses the timestamping code that checks for file size.
         #### The timestamping code should be smarter about file size.  */
      if (opt.save_headers && hs->restval == 0)
        fwrite (head, 1, strlen (head), fp);
    }

  /* Read the response body.  */
  if (contlen != -1)
    /* If content-length is present, read that much; otherwise, read
       until EOF.  The HTTP spec doesn't require the server to
       actually close the connection when it's done sending data. */
    flags |= rb_read_exactly;
  if (fp != NULL && hs->restval > 0 && contrange == 0)
    /* If the server ignored our range request, instruct fd_read_body
       to skip the first RESTVAL bytes of body.  */
    flags |= rb_skip_startpos;
  if (chunked_transfer_encoding)
    flags |= rb_chunked_transfer_encoding;

  if (hs->remote_encoding == ENC_GZIP)
    flags |= rb_compressed_gzip;

  hs->len = hs->restval;
  hs->rd_size = 0;
  /* Download the response body and write it to fp.
     If we are working on a WARC file, we simultaneously write the
     response body to warc_tmp.  */
  hs->res = fd_read_body (hs->local_file, sock, fp, contlen != -1 ? contlen : 0,
                          hs->restval, &hs->rd_size, &hs->len, &hs->dltime,
                          flags, warc_tmp);
  if (hs->res >= 0)
    {
      if (warc_tmp != NULL)
        {
          /* Create a response record and write it to the WARC file.
             Note: per the WARC standard, the request and response should share
             the same date header.  We re-use the timestamp of the request.
             The response record should also refer to the uuid of the request.  */
          bool r = warc_write_response_record (url, warc_timestamp_str,
                                               warc_request_uuid, warc_ip,
                                               warc_tmp, warc_payload_offset,
                                               type, statcode, hs->newloc);

          /* warc_write_response_record has closed warc_tmp. */

          if (! r)
            return WARC_ERR;
        }

      return RETRFINISHED;
    }

  if (warc_tmp != NULL)
    fclose (warc_tmp);

  if (hs->res == -2)
    {
      /* Error while writing to fd. */
      return FWRITEERR;
    }
  else if (hs->res == -3)
    {
      /* Error while writing to warc_tmp. */
      return WARC_TMP_FWRITEERR;
    }
  else
    {
      /* A read error! */
      xfree (hs->rderrmsg);
      hs->rderrmsg = xstrdup (fd_errstr (sock));
      return RETRFINISHED;
    }
}

#define BEGINS_WITH(line, string_constant)                               \
  (!c_strncasecmp (line, string_constant, sizeof (string_constant) - 1)    \
   && (c_isspace (line[sizeof (string_constant) - 1])                      \
       || !line[sizeof (string_constant) - 1]))

#define SET_USER_AGENT(req) do {                                         \
  if (!opt.useragent)                                                    \
    request_set_header (req, "User-Agent",                               \
                        aprintf ("Wget/%s",                              \
                        version_string),                                 \
                        rel_value);                                      \
  else if (*opt.useragent)                                               \
    request_set_header (req, "User-Agent", opt.useragent, rel_none);     \
} while (0)

/*
   Convert time_t to one of valid HTTP date formats
   ie. rfc1123-date.

   HTTP-date    = rfc1123-date | rfc850-date | asctime-date
   rfc1123-date = wkday "," SP date1 SP time SP "GMT"
   rfc850-date  = weekday "," SP date2 SP time SP "GMT"
   asctime-date = wkday SP date3 SP time SP 4DIGIT
   date1        = 2DIGIT SP month SP 4DIGIT
                  ; day month year (e.g., 02 Jun 1982)
   date2        = 2DIGIT "-" month "-" 2DIGIT
                  ; day-month-year (e.g., 02-Jun-82)
   date3        = month SP ( 2DIGIT | ( SP 1DIGIT ))
                  ; month day (e.g., Jun  2)
   time         = 2DIGIT ":" 2DIGIT ":" 2DIGIT
                  ; 00:00:00 - 23:59:59
   wkday        = "Mon" | "Tue" | "Wed"
                | "Thu" | "Fri" | "Sat" | "Sun"
   weekday      = "Monday" | "Tuesday" | "Wednesday"
                | "Thursday" | "Friday" | "Saturday" | "Sunday"
   month        = "Jan" | "Feb" | "Mar" | "Apr"
                | "May" | "Jun" | "Jul" | "Aug"
                | "Sep" | "Oct" | "Nov" | "Dec"

   source: RFC2616  */
static uerr_t
time_to_rfc1123 (time_t time, char *buf, size_t bufsize)
{
  static const char *wkday[] = { "Sun", "Mon", "Tue", "Wed",
                                 "Thu", "Fri", "Sat" };
  static const char *month[] = { "Jan", "Feb", "Mar", "Apr",
                                 "May", "Jun", "Jul", "Aug",
                                 "Sep", "Oct", "Nov", "Dec" };
  /* rfc1123 example: Thu, 01 Jan 1998 22:12:57 GMT  */
  static const char *time_format = "%s, %02d %s %04d %02d:%02d:%02d GMT";

  struct tm *gtm = gmtime (&time);
  if (!gtm)
    {
      logprintf (LOG_NOTQUIET,
                 _("gmtime failed. This is probably a bug.\n"));
      return TIMECONV_ERR;
    }

  snprintf (buf, bufsize, time_format, wkday[gtm->tm_wday],
            gtm->tm_mday, month[gtm->tm_mon],
            gtm->tm_year + 1900, gtm->tm_hour,
            gtm->tm_min, gtm->tm_sec);

  return RETROK;
}

static struct request *
initialize_request (const struct url *u, struct http_stat *hs, int *dt, struct url *proxy,
                    bool inhibit_keep_alive, bool *basic_auth_finished,
                    wgint *body_data_size, char **user, char **passwd, uerr_t *ret)
{
  bool head_only = !!(*dt & HEAD_ONLY);
  struct request *req;

  /* Prepare the request to send. */
  {
    char *meth_arg;
    const char *meth = "GET";
    if (head_only)
      meth = "HEAD";
    else if (opt.method)
      meth = opt.method;
    /* Use the full path, i.e. one that includes the leading slash and
       the query string.  E.g. if u->path is "foo/bar" and u->query is
       "param=value", full_path will be "/foo/bar?param=value".  */
    if (proxy
#ifdef HAVE_SSL
        /* When using SSL over proxy, CONNECT establishes a direct
           connection to the HTTPS server.  Therefore use the same
           argument as when talking to the server directly. */
        && u->scheme != SCHEME_HTTPS
#endif
        )
      meth_arg = xstrdup (u->url);
    else
      meth_arg = url_full_path (u);
    req = request_new (meth, meth_arg);
  }

  /* Generate the Host header, HOST:PORT.  Take into account that:

     - Broken server-side software often doesn't recognize the PORT
       argument, so we must generate "Host: www.server.com" instead of
       "Host: www.server.com:80" (and likewise for https port).

     - IPv6 addresses contain ":", so "Host: 3ffe:8100:200:2::2:1234"
       becomes ambiguous and needs to be rewritten as "Host:
       [3ffe:8100:200:2::2]:1234".  */
  {
    /* Formats arranged for hfmt[add_port][add_squares].  */
    static const char *hfmt[][2] = {
      { "%s", "[%s]" }, { "%s:%d", "[%s]:%d" }
    };
    int add_port = u->port != scheme_default_port (u->scheme);
    int add_squares = strchr (u->host, ':') != NULL;
    request_set_header (req, "Host",
                        aprintf (hfmt[add_port][add_squares], u->host, u->port),
                        rel_value);
  }

  request_set_header (req, "Referer", hs->referer, rel_none);
  if (*dt & SEND_NOCACHE)
    {
      /* Cache-Control MUST be obeyed by all HTTP/1.1 caching mechanisms...  */
      request_set_header (req, "Cache-Control", "no-cache", rel_none);

      /* ... but some HTTP/1.0 caches doesn't implement Cache-Control.  */
      request_set_header (req, "Pragma", "no-cache", rel_none);
    }
  if (*dt & IF_MODIFIED_SINCE)
    {
      char strtime[32];
      uerr_t err = time_to_rfc1123 (hs->orig_file_tstamp, strtime, countof (strtime));

      if (err != RETROK)
        {
          logputs (LOG_VERBOSE, _("Cannot convert timestamp to http format. "
                                  "Falling back to time 0 as last modification "
                                  "time.\n"));
          strcpy (strtime, "Thu, 01 Jan 1970 00:00:00 GMT");
        }
      request_set_header (req, "If-Modified-Since", xstrdup (strtime), rel_value);
    }
  if (hs->restval)
    request_set_header (req, "Range",
                        aprintf ("bytes=%s-",
                                 number_to_static_string (hs->restval)),
                        rel_value);
  SET_USER_AGENT (req);
  request_set_header (req, "Accept", "*/*", rel_none);
#ifdef HAVE_LIBZ
  if (opt.compression != compression_none)
    request_set_header (req, "Accept-Encoding", "gzip", rel_none);
  else
#endif
    request_set_header (req, "Accept-Encoding", "identity", rel_none);

  /* Find the username with priority */
  if (u->user)
    *user = u->user;
  else if (opt.user && (opt.use_askpass || opt.ask_passwd))
    *user = opt.user;
  else if (opt.http_user)
    *user = opt.http_user;
  else if (opt.user)
    *user = opt.user;
  else
    *user = NULL;

  /* Find the password with priority */
  if (u->passwd)
    *passwd = u->passwd;
  else if (opt.passwd && (opt.use_askpass || opt.ask_passwd))
    *passwd = opt.passwd;
  else if (opt.http_passwd)
    *passwd = opt.http_passwd;
  else if (opt.passwd)
    *passwd = opt.passwd;
  else
    *passwd = NULL;

  /* Check for ~/.netrc if none of the above match */
  if (opt.netrc && (!*user || !*passwd))
    search_netrc (u->host, (const char **) user, (const char **) passwd, 0, NULL);

  /* We only do "site-wide" authentication with "global" user/password
   * values unless --auth-no-challenge has been requested; URL user/password
   * info overrides. */
  if (*user && *passwd && (!u->user || opt.auth_without_challenge))
    {
      /* If this is a host for which we've already received a Basic
       * challenge, we'll go ahead and send Basic authentication creds. */
      *basic_auth_finished = maybe_send_basic_creds (u->host, *user, *passwd, req);
    }

  if (inhibit_keep_alive)
    request_set_header (req, "Connection", "Close", rel_none);
  else
    {
      request_set_header (req, "Connection", "Keep-Alive", rel_none);
      if (proxy)
        request_set_header (req, "Proxy-Connection", "Keep-Alive", rel_none);
    }

  if (opt.method)
    {

      if (opt.body_data || opt.body_file)
        {
          request_set_header (req, "Content-Type",
                              "application/x-www-form-urlencoded", rel_none);

          if (opt.body_data)
            *body_data_size = strlen (opt.body_data);
          else
            {
              *body_data_size = file_size (opt.body_file);
              if (*body_data_size == -1)
                {
                  logprintf (LOG_NOTQUIET, _("BODY data file %s missing: %s\n"),
                             quote (opt.body_file), strerror (errno));
                  request_free (&req);
                  *ret = FILEBADFILE;
                  return NULL;
                }
            }
          request_set_header (req, "Content-Length",
                              xstrdup (number_to_static_string (*body_data_size)),
                              rel_value);
        }
      else if (c_strcasecmp (opt.method, "post") == 0
               || c_strcasecmp (opt.method, "put") == 0
               || c_strcasecmp (opt.method, "patch") == 0)
        request_set_header (req, "Content-Length", "0", rel_none);
    }
  return req;
}

static void
initialize_proxy_configuration (const struct url *u, struct request *req,
                                struct url *proxy, char **proxyauth)
{
  char *proxy_user, *proxy_passwd;
  /* For normal username and password, URL components override
     command-line/wgetrc parameters.  With proxy
     authentication, it's the reverse, because proxy URLs are
     normally the "permanent" ones, so command-line args
     should take precedence.  */
  if (opt.proxy_user && opt.proxy_passwd)
    {
      proxy_user = opt.proxy_user;
      proxy_passwd = opt.proxy_passwd;
    }
  else
    {
      proxy_user = proxy->user;
      proxy_passwd = proxy->passwd;
    }
  /* #### This does not appear right.  Can't the proxy request,
     say, `Digest' authentication?  */
  if (proxy_user && proxy_passwd)
    *proxyauth = basic_authentication_encode (proxy_user, proxy_passwd);

  /* Proxy authorization over SSL is handled below. */
#ifdef HAVE_SSL
  if (u->scheme != SCHEME_HTTPS)
#endif
    request_set_header (req, "Proxy-Authorization", *proxyauth, rel_value);
}

static uerr_t
establish_connection (const struct url *u, const struct url **conn_ref,
                      struct http_stat *hs, struct url *proxy,
                      char **proxyauth,
                      struct request **req_ref, bool *using_ssl,
                      bool inhibit_keep_alive,
                      int *sock_ref)
{
  bool host_lookup_failed = false;
  int sock = *sock_ref;
  struct request *req = *req_ref;
  const struct url *conn = *conn_ref;
  struct response *resp;
  int write_error;
  int statcode;

  if (! inhibit_keep_alive)
    {
      /* Look for a persistent connection to target host, unless a
         proxy is used.  The exception is when SSL is in use, in which
         case the proxy is nothing but a passthrough to the target
         host, registered as a connection to the latter.  */
      const struct url *relevant = conn;
#ifdef HAVE_SSL
      if (u->scheme == SCHEME_HTTPS)
        relevant = u;
#endif

      if (persistent_available_p (relevant->host, relevant->port,
#ifdef HAVE_SSL
                                  relevant->scheme == SCHEME_HTTPS,
#else
                                  0,
#endif
                                  &host_lookup_failed))
        {
          int family = socket_family (pconn.socket, ENDPOINT_PEER);
          sock = pconn.socket;
          *using_ssl = pconn.ssl;
#if ENABLE_IPV6
          if (family == AF_INET6)
             logprintf (LOG_VERBOSE, _("Reusing existing connection to [%s]:%d.\n"),
                        quotearg_style (escape_quoting_style, pconn.host),
                         pconn.port);
          else
#endif
             logprintf (LOG_VERBOSE, _("Reusing existing connection to %s:%d.\n"),
                        quotearg_style (escape_quoting_style, pconn.host),
                        pconn.port);
          DEBUGP (("Reusing fd %d.\n", sock));
          if (pconn.authorized)
            /* If the connection is already authorized, the "Basic"
               authorization added by code above is unnecessary and
               only hurts us.  */
            request_remove_header (req, "Authorization");
        }
      else if (host_lookup_failed)
        {
          logprintf(LOG_NOTQUIET,
                    _("%s: unable to resolve host address %s\n"),
                    exec_name, quote (relevant->host));
          return HOSTERR;
        }
      else if (sock != -1)
        {
          sock = -1;
        }
    }

  if (sock < 0)
    {
      sock = connect_to_host (conn->host, conn->port);
      if (sock == E_HOST)
        return HOSTERR;
      else if (sock < 0)
        return (retryable_socket_connect_error (errno)
                ? CONERROR : CONIMPOSSIBLE);

#ifdef HAVE_SSL
      if (proxy && u->scheme == SCHEME_HTTPS)
        {
          char *head;
          char *message;
          /* When requesting SSL URLs through proxies, use the
             CONNECT method to request passthrough.  */
          struct request *connreq = request_new ("CONNECT",
                              aprintf ("%s:%d", u->host, u->port));
          SET_USER_AGENT (connreq);
          if (proxyauth)
            {
              request_set_header (connreq, "Proxy-Authorization",
                                  *proxyauth, rel_value);
              /* Now that PROXYAUTH is part of the CONNECT request,
                 zero it out so we don't send proxy authorization with
                 the regular request below.  */
              *proxyauth = NULL;
            }
          request_set_header (connreq, "Host",
                              aprintf ("%s:%d", u->host, u->port),
                              rel_value);

          write_error = request_send (connreq, sock, 0);
          request_free (&connreq);
          if (write_error < 0)
            {
              CLOSE_INVALIDATE (sock);
              return WRITEFAILED;
            }

          head = read_http_response_head (sock);
          if (!head)
            {
              logprintf (LOG_VERBOSE, _("Failed reading proxy response: %s\n"),
                         fd_errstr (sock));
              CLOSE_INVALIDATE (sock);
              return HERR;
            }
          message = NULL;
          if (!*head)
            {
              xfree (head);
              goto failed_tunnel;
            }
          DEBUGP (("proxy responded with: [%s]\n", head));

          resp = resp_new (head);
          statcode = resp_status (resp, &message);
          if (statcode < 0)
            {
              char *tms = datetime_str (time (NULL));
              logprintf (LOG_VERBOSE, "%d\n", statcode);
              logprintf (LOG_NOTQUIET, _("%s ERROR %d: %s.\n"), tms, statcode,
                         quotearg_style (escape_quoting_style,
                                         _("Malformed status line")));
              xfree (head);
              return HERR;
            }
          xfree (hs->message);
          hs->message = xstrdup (message);
          resp_free (&resp);
          xfree (head);
          if (statcode != 200)
            {
            failed_tunnel:
              logprintf (LOG_NOTQUIET, _("Proxy tunneling failed: %s"),
                         message ? quotearg_style (escape_quoting_style, message) : "?");
              xfree (message);
              return CONSSLERR;
            }
          xfree (message);

          /* SOCK is now *really* connected to u->host, so update CONN
             to reflect this.  That way register_persistent will
             register SOCK as being connected to u->host:u->port.  */
          conn = u;
        }

      if (conn->scheme == SCHEME_HTTPS)
        {
          if (!ssl_connect_wget (sock, u->host, NULL))
            {
              CLOSE_INVALIDATE (sock);
              return CONSSLERR;
            }
          else if (!ssl_check_certificate (sock, u->host))
            {
              CLOSE_INVALIDATE (sock);
              return VERIFCERTERR;
            }
          *using_ssl = true;
        }
#endif /* HAVE_SSL */
    }
  *conn_ref = conn;
  *req_ref = req;
  *sock_ref = sock;
  return RETROK;
}

static uerr_t
set_file_timestamp (struct http_stat *hs)
{
  bool local_dot_orig_file_exists = false;
  char *local_filename = NULL;
  struct stat st;
  char buf[1024];

  if (opt.backup_converted)
    /* If -K is specified, we'll act on the assumption that it was specified
        last time these files were downloaded as well, and instead of just
        comparing local file X against server file X, we'll compare local
        file X.orig (if extant, else X) against server file X.  If -K
        _wasn't_ specified last time, or the server contains files called
        *.orig, -N will be back to not operating correctly with -k. */
    {
      size_t filename_len = strlen (hs->local_file);
      char *filename_plus_orig_suffix;

      if (filename_len + sizeof (ORIG_SFX) > sizeof (buf))
        filename_plus_orig_suffix = xmalloc (filename_len + sizeof (ORIG_SFX));
      else
        filename_plus_orig_suffix = buf;

      /* Would a single s[n]printf() call be faster?  --dan

          Definitely not.  sprintf() is horribly slow.  It's a
          different question whether the difference between the two
          affects a program.  Usually I'd say "no", but at one
          point I profiled Wget, and found that a measurable and
          non-negligible amount of time was lost calling sprintf()
          in url.c.  Replacing sprintf with inline calls to
          strcpy() and number_to_string() made a difference.
          --hniksic */
      memcpy (filename_plus_orig_suffix, hs->local_file, filename_len);
      memcpy (filename_plus_orig_suffix + filename_len,
              ORIG_SFX, sizeof (ORIG_SFX));

      /* Try to stat() the .orig file. */
      if (stat (filename_plus_orig_suffix, &st) == 0)
        {
          local_dot_orig_file_exists = true;
          local_filename = filename_plus_orig_suffix;
        }
    }

  if (!local_dot_orig_file_exists)
    /* Couldn't stat() <file>.orig, so try to stat() <file>. */
    if (stat (hs->local_file, &st) == 0)
      {
        if (local_filename != buf)
          xfree (local_filename);
        local_filename = hs->local_file;
      }

  if (local_filename != NULL)
    /* There was a local file, so we'll check later to see if the version
        the server has is the same version we already have, allowing us to
        skip a download. */
    {
      if (local_filename == buf || local_filename == hs->local_file)
        hs->orig_file_name = xstrdup (local_filename); // on stack or a copy, make a heap copy
      else
        hs->orig_file_name = local_filename; // was previously malloc'ed
      hs->orig_file_size = st.st_size;
      hs->orig_file_tstamp = st.st_mtime;
#ifdef WINDOWS
      /* Modification time granularity is 2 seconds for Windows, so
          increase local time by 1 second for later comparison. */
      ++hs->orig_file_tstamp;
#endif
      hs->timestamp_checked = true;
    }

  return RETROK;
}

static uerr_t
check_file_output (const struct url *u, struct http_stat *hs,
                   struct response *resp, char *hdrval, size_t hdrsize)
{
  /* Determine the local filename if needed. Notice that if -O is used
   * hstat.local_file is set by http_loop to the argument of -O. */
  if (!hs->local_file)
    {
      char *local_file = NULL;

      /* Honor Content-Disposition whether possible. */
      if (!opt.content_disposition
          || !resp_header_copy (resp, "Content-Disposition",
                                hdrval, hdrsize)
          || !parse_content_disposition (hdrval, &local_file))
        {
          /* The Content-Disposition header is missing or broken.
           * Choose unique file name according to given URL. */
          hs->local_file = url_file_name (u, NULL);
        }
      else
        {
          DEBUGP (("Parsed filename from Content-Disposition: %s\n",
                  local_file));
          hs->local_file = url_file_name (u, local_file);
        }

      xfree (local_file);
    }

  hs->temporary = opt.delete_after || opt.spider || !acceptable (hs->local_file);
  if (hs->temporary)
    {
      char *tmp = aprintf ("%s.tmp", hs->local_file);
      xfree (hs->local_file);
      hs->local_file = tmp;
    }

  /* TODO: perform this check only once. */
  if (!hs->existence_checked && file_exists_p (hs->local_file, NULL))
    {
      if (opt.noclobber && !opt.output_document)
        {
          /* If opt.noclobber is turned on and file already exists, do not
             retrieve the file. But if the output_document was given, then this
             test was already done and the file didn't exist. Hence the !opt.output_document */
          return RETRUNNEEDED;
        }
      else if (!ALLOW_CLOBBER)
        {
          char *unique = unique_name_passthrough (hs->local_file);
          if (unique != hs->local_file)
            xfree (hs->local_file);
          hs->local_file = unique;
        }
    }
  hs->existence_checked = true;

  /* Support timestamping */
  if (opt.timestamping && !hs->timestamp_checked)
    {
      uerr_t timestamp_err = set_file_timestamp (hs);
      if (timestamp_err != RETROK)
        return timestamp_err;
    }
  return RETROK;
}

static uerr_t
check_auth (const struct url *u, char *user, char *passwd, struct response *resp,
            struct request *req, bool *ntlm_seen_ref, bool *retry,
            bool *basic_auth_finished_ref, bool *auth_finished_ref)
{
  uerr_t auth_err = RETROK;
  bool basic_auth_finished = *basic_auth_finished_ref;
  bool auth_finished = *auth_finished_ref;
  bool ntlm_seen = *ntlm_seen_ref;
  char buf[256], *tmp = NULL;

  *retry = false;

  if (!auth_finished && (user && passwd))
    {
      /* IIS sends multiple copies of WWW-Authenticate, one with
         the value "negotiate", and other(s) with data.  Loop over
         all the occurrences and pick the one we recognize.  */
      int wapos;
      const char *www_authenticate = NULL;
      const char *wabeg, *waend;
      const char *digest = NULL, *basic = NULL, *ntlm = NULL;

      for (wapos = 0; !ntlm
             && (wapos = resp_header_locate (resp, "WWW-Authenticate", wapos,
                                             &wabeg, &waend)) != -1;
           ++wapos)
        {
          param_token name, value;
          size_t len = waend - wabeg;

          if (tmp != buf)
            xfree (tmp);

          if (len < sizeof (buf))
            tmp = buf;
          else
            tmp = xmalloc (len + 1);

          memcpy (tmp, wabeg, len);
          tmp[len] = 0;

          www_authenticate = tmp;

          for (;!ntlm;)
            {
              /* extract the auth-scheme */
              while (c_isspace (*www_authenticate)) www_authenticate++;
              name.e = name.b = www_authenticate;
              while (*name.e && !c_isspace (*name.e)) name.e++;

              if (name.b == name.e)
                break;

              DEBUGP (("Auth scheme found '%.*s'\n", (int) (name.e - name.b), name.b));

              if (known_authentication_scheme_p (name.b, name.e))
                {
                  if (BEGINS_WITH (name.b, "NTLM"))
                    {
                      ntlm = name.b;
                      break; /* this is the most secure challenge, stop here */
                    }
                  else if (!digest && BEGINS_WITH (name.b, "Digest"))
                    digest = name.b;
                  else if (!basic && BEGINS_WITH (name.b, "Basic"))
                    basic = name.b;
                }

              /* now advance over the auth-params */
              www_authenticate = name.e;
              DEBUGP (("Auth param list '%s'\n", www_authenticate));
              while (extract_param (&www_authenticate, &name, &value, ',', NULL) && name.b && value.b)
                {
                  DEBUGP (("Auth param %.*s=%.*s\n",
                           (int) (name.e - name.b), name.b, (int) (value.e - value.b), value.b));
                }
            }
        }

      if (!basic && !digest && !ntlm)
        {
          /* If the authentication header is missing or
             unrecognized, there's no sense in retrying.  */
          logputs (LOG_NOTQUIET, _("Unknown authentication scheme.\n"));
        }
      else if (!basic_auth_finished
               || !basic)
        {
          char *pth = url_full_path (u);
          const char *value;
          uerr_t *auth_stat;
          auth_stat = xmalloc (sizeof (uerr_t));
          *auth_stat = RETROK;

          if (ntlm)
            www_authenticate = ntlm;
          else if (digest)
            www_authenticate = digest;
          else
            www_authenticate = basic;

          logprintf (LOG_NOTQUIET, _("Authentication selected: %s\n"), www_authenticate);

          value =  create_authorization_line (www_authenticate,
                                              user, passwd,
                                              request_method (req),
                                              pth,
                                              &auth_finished,
                                              auth_stat);

          auth_err = *auth_stat;
          xfree (auth_stat);
          xfree (pth);
          if (auth_err == RETROK)
            {
              request_set_header (req, "Authorization", value, rel_value);

              if (BEGINS_WITH (www_authenticate, "NTLM"))
                ntlm_seen = true;
              else if (!u->user && BEGINS_WITH (www_authenticate, "Basic"))
                {
                  /* Need to register this host as using basic auth,
                   * so we automatically send creds next time. */
                  register_basic_auth_host (u->host);
                }

              *retry = true;
              goto cleanup;
            }
          else
            {
              /* Creating the Authorization header went wrong */
              xfree (value);
            }
        }
      else
        {
          /* We already did Basic auth, and it failed. Gotta
           * give up. */
        }
    }

 cleanup:
   if (tmp != buf)
     xfree (tmp);
  *ntlm_seen_ref = ntlm_seen;
  *basic_auth_finished_ref = basic_auth_finished;
  *auth_finished_ref = auth_finished;
  return auth_err;
}

static uerr_t
open_output_stream (struct http_stat *hs, int count, FILE **fp)
{
/* 2005-06-17 SMS.
   For VMS, define common fopen() optional arguments.
*/
#ifdef __VMS
# define FOPEN_OPT_ARGS "fop=sqo", "acc", acc_cb, &open_id
# define FOPEN_BIN_FLAG 3
#else /* def __VMS */
# define FOPEN_BIN_FLAG true
#endif /* def __VMS [else] */

  /* Open the local file.  */
  if (!output_stream)
    {
      mkalldirs (hs->local_file);
      if (opt.backups)
        rotate_backups (hs->local_file);
      if (hs->restval)
        {
#ifdef __VMS
          int open_id;

          open_id = 21;
          *fp = fopen (hs->local_file, "ab", FOPEN_OPT_ARGS);
#else /* def __VMS */
          *fp = fopen (hs->local_file, "ab");
#endif /* def __VMS [else] */
        }
      else if (ALLOW_CLOBBER || count > 0)
        {
          if (opt.unlink_requested && file_exists_p (hs->local_file, NULL))
            {
              if (unlink (hs->local_file) < 0)
                {
                  logprintf (LOG_NOTQUIET, "%s: %s\n", hs->local_file,
                             strerror (errno));
                  return UNLINKERR;
                }
            }

#ifdef __VMS
          int open_id;

          open_id = 22;
          *fp = fopen (hs->local_file, "wb", FOPEN_OPT_ARGS);
#else /* def __VMS */
          if (hs->temporary)
            {
              *fp = fdopen (open (hs->local_file, O_BINARY | O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR), "wb");
            }
          else
            {
              *fp = fopen (hs->local_file, "wb");
            }

#endif /* def __VMS [else] */
        }
      else
        {
          *fp = fopen_excl (hs->local_file, FOPEN_BIN_FLAG);
          if (!*fp && errno == EEXIST)
            {
              /* We cannot just invent a new name and use it (which is
                 what functions like unique_create typically do)
                 because we told the user we'd use this name.
                 Instead, return and retry the download.  */
              logprintf (LOG_NOTQUIET,
                         _("%s has sprung into existence.\n"),
                         hs->local_file);
              return FOPEN_EXCL_ERR;
            }
        }
      if (!*fp)
        {
          logprintf (LOG_NOTQUIET, "%s: %s\n", hs->local_file, strerror (errno));
          return FOPENERR;
        }
    }
  else
    *fp = output_stream;

  /* Print fetch message, if opt.verbose.  */
  logprintf (LOG_VERBOSE, _("Saving to: %s\n"),
             HYPHENP (hs->local_file) ? quote ("STDOUT") : quote (hs->local_file));

  return RETROK;
}

/* Set proper type flags based on type string.  */
static void
set_content_type (int *dt, const char *type)
{
  /* If content-type is not given, assume text/html.  This is because
     of the multitude of broken CGI's that "forget" to generate the
     content-type.  */
  if (!type ||
      0 == c_strcasecmp (type, TEXTHTML_S) ||
      0 == c_strcasecmp (type, TEXTXHTML_S))
    *dt |= TEXTHTML;
  else
    *dt &= ~TEXTHTML;

  if (type &&
      0 == c_strcasecmp (type, TEXTCSS_S))
    *dt |= TEXTCSS;
  else
    *dt &= ~TEXTCSS;
}

#ifdef HAVE_METALINK
/* Will return proper metalink_t structure if enough data was found in
   http response resp. Otherwise returns NULL.
   Two exit points: one for success and one for failure.  */
static metalink_t *
metalink_from_http (const struct response *resp, const struct http_stat *hs,
                    const struct url *u)
{
  metalink_t *metalink = NULL;
  metalink_file_t *mfile = xnew0 (metalink_file_t);
  const char *val_beg, *val_end;
  int res_count = 0, meta_count = 0, hash_count = 0, sig_count = 0, i;

  DEBUGP (("Checking for Metalink in HTTP response\n"));

  /* Initialize metalink file for our simple use case.  */
  if (hs->local_file)
    mfile->name = xstrdup (hs->local_file);
  else
    mfile->name = url_file_name (u, NULL);

  /* Begin with 1-element array (for 0-termination). */
  mfile->checksums = xnew0 (metalink_checksum_t *);
  mfile->resources = xnew0 (metalink_resource_t *);
  mfile->metaurls = xnew0 (metalink_metaurl_t *);

  /* Process the Content-Type header.  */
  if (resp_header_locate (resp, "Content-Type", 0, &val_beg, &val_end) != -1)
    {
      metalink_metaurl_t murl = {0};

      const char *type_beg, *type_end;
      char *typestr = NULL;
      char *namestr = NULL;
      size_t type_len;

      DEBUGP (("Processing Content-Type header...\n"));

      /* Find beginning of type.  */
      type_beg = val_beg;
      while (type_beg < val_end && c_isspace (*type_beg))
        type_beg++;

      /* Find end of type.  */
      type_end = type_beg + 1;
      while (type_end < val_end &&
             *type_end != ';' &&
             *type_end != ' ' &&
             *type_end != '\r' &&
             *type_end != '\n')
        type_end++;

      if (type_beg >= val_end || type_end > val_end)
        {
          DEBUGP (("Invalid Content-Type header. Ignoring.\n"));
          goto skip_content_type;
        }

      type_len = type_end - type_beg;
      typestr = xstrndup (type_beg, type_len);

      DEBUGP (("Content-Type: %s\n", typestr));

      if (strcmp (typestr, "application/metalink4+xml"))
        {
          xfree (typestr);
          goto skip_content_type;
        }

      /*
        Valid ranges for the "pri" attribute are from
        1 to 999999.  Mirror servers with a lower value of the "pri"
        attribute have a higher priority, while mirrors with an undefined
        "pri" attribute are considered to have a value of 999999, which is
        the lowest priority.

        rfc6249 section 3.1
      */
      murl.priority = DEFAULT_PRI;

      murl.mediatype = typestr;
      typestr = NULL;

      if (opt.content_disposition
          && resp_header_locate (resp, "Content-Disposition", 0, &val_beg, &val_end) != -1)
        {
          find_key_value (val_beg, val_end, "filename", &namestr);
          murl.name = namestr;
          namestr = NULL;
        }

      murl.url = xstrdup (u->url);

      DEBUGP (("URL=%s\n", murl.url));
      DEBUGP (("MEDIATYPE=%s\n", murl.mediatype));
      DEBUGP (("NAME=%s\n", murl.name ? murl.name : ""));
      DEBUGP (("PRIORITY=%d\n", murl.priority));

      /* 1 slot from new resource, 1 slot for null-termination.  */
      mfile->metaurls = xrealloc (mfile->metaurls,
                                  sizeof (metalink_metaurl_t *) * (meta_count + 2));
      mfile->metaurls[meta_count] = xnew0 (metalink_metaurl_t);
      *mfile->metaurls[meta_count] = murl;
      meta_count++;
    }
skip_content_type:

  /* Find all Link headers.  */
  for (i = 0;
       (i = resp_header_locate (resp, "Link", i, &val_beg, &val_end)) != -1;
       i++)
    {
      char *rel = NULL, *reltype = NULL;
      char *urlstr = NULL;
      const char *url_beg, *url_end, *attrs_beg;
      size_t url_len;

      /* Sample Metalink Link headers:

           Link: <http://www2.example.com/dir1/dir2/dir3/dir4/dir5/example.ext>;
           rel=duplicate; pri=1; pref; geo=gb; depth=4

           Link: <http://example.com/example.ext.asc>; rel=describedby;
           type="application/pgp-signature"
       */

      /* Find beginning of URL.  */
      url_beg = val_beg;
      while (url_beg < val_end - 1 && c_isspace (*url_beg))
        url_beg++;

      /* Find end of URL.  */
      /* The convention here is that end ptr points to one element after
         end of string. In this case, it should be pointing to the '>', which
         is one element after end of actual URL. Therefore, it should never point
         to val_end, which is one element after entire header value string.  */
      url_end = url_beg + 1;
      while (url_end < val_end - 1 && *url_end != '>')
        url_end++;

      if (url_beg >= val_end || url_end >= val_end ||
          *url_beg != '<' || *url_end != '>')
        {
          DEBUGP (("This is not a valid Link header. Ignoring.\n"));
          continue;
        }

      /* Skip <.  */
      url_beg++;
      url_len = url_end - url_beg;

      /* URL found. Now handle the attributes.  */
      attrs_beg = url_end + 1;

      /* First we need to find out what type of link it is. Currently, we
         support rel=duplicate and rel=describedby.  */
      if (!find_key_value (attrs_beg, val_end, "rel", &rel))
        {
          DEBUGP (("No rel value in Link header, skipping.\n"));
          continue;
        }

      urlstr = xstrndup (url_beg, url_len);
      DEBUGP (("URL=%s\n", urlstr));
      DEBUGP (("rel=%s\n", rel));

      if (!strcmp (rel, "describedby"))
        find_key_value (attrs_beg, val_end, "type", &reltype);

      /* Handle signatures.
         Libmetalink only supports one signature per file. Therefore we stop
         as soon as we successfully get first supported signature.  */
      if (sig_count == 0 &&
          reltype && !strcmp (reltype, "application/pgp-signature"))
        {
          /* Download the signature to a temporary file.  */
          FILE *_output_stream = output_stream;
          bool _output_stream_regular = output_stream_regular;

          output_stream = tmpfile ();
          if (output_stream)
            {
              struct iri *iri = iri_new ();
              struct url *url;
              int url_err;

              set_uri_encoding (iri, opt.locale, true);
              url = url_parse (urlstr, &url_err, iri, false);

              if (!url)
                {
                  char *error = url_error (urlstr, url_err);
                  logprintf (LOG_NOTQUIET, _("When downloading signature:\n"
                                             "%s: %s.\n"), urlstr, error);
                  xfree (error);
                  iri_free (iri);
                }
              else
                {
                  /* Avoid recursive Metalink from HTTP headers.  */
                  bool _metalink_http = opt.metalink_over_http;
                  uerr_t retr_err;

                  opt.metalink_over_http = false;
                  retr_err = retrieve_url (url, urlstr, NULL, NULL,
                                           NULL, NULL, false, iri, false);
                  opt.metalink_over_http = _metalink_http;

                  url_free (url);
                  iri_free (iri);

                  if (retr_err == RETROK)
                    {
                      /* Signature is in the temporary file. Read it into
                         metalink resource structure.  */
                      metalink_signature_t msig;
                      size_t siglen;

                      fseek (output_stream, 0, SEEK_END);
                      siglen = ftell (output_stream);
                      fseek (output_stream, 0, SEEK_SET);

                      DEBUGP (("siglen=%lu\n", siglen));

                      msig.signature = xmalloc (siglen + 1);
                      if (fread (msig.signature, siglen, 1, output_stream) != 1)
                        {
                          logputs (LOG_NOTQUIET,
                                   _("Unable to read signature content from "
                                     "temporary file. Skipping.\n"));
                          xfree (msig.signature);
                        }
                      else
                        {
                          msig.signature[siglen] = '\0'; /* Just in case.  */
                          msig.mediatype = xstrdup ("application/pgp-signature");

                          DEBUGP (("Signature (%s):\n%s\n",
                                   msig.mediatype, msig.signature));

                          mfile->signature = xnew (metalink_signature_t);
                          *mfile->signature = msig;

                          sig_count++;
                        }
                    }
                }
              fclose (output_stream);
            }
          else
            {
              logputs (LOG_NOTQUIET, _("Could not create temporary file. "
                                       "Skipping signature download.\n"));
            }
          output_stream_regular = _output_stream_regular;
          output_stream = _output_stream;
        } /* Iterate over signatures.  */

        /* Handle Metalink resources.  */
      else if (!strcmp (rel, "duplicate"))
        {
          metalink_resource_t mres = {0};
          char *pristr;

          /*
             Valid ranges for the "pri" attribute are from
             1 to 999999.  Mirror servers with a lower value of the "pri"
             attribute have a higher priority, while mirrors with an undefined
             "pri" attribute are considered to have a value of 999999, which is
             the lowest priority.

             rfc6249 section 3.1
           */
          mres.priority = DEFAULT_PRI;
          if (find_key_value (url_end, val_end, "pri", &pristr))
            {
              long pri;
              char *end_pristr;
              /* Do not care for errno since 0 is error in this case.  */
              pri = strtol (pristr, &end_pristr, 10);
              if (end_pristr != pristr + strlen (pristr) ||
                  !VALID_PRI_RANGE (pri))
                {
                  /* This is against the specification, so let's inform the user.  */
                  logprintf (LOG_NOTQUIET,
                             _("Invalid pri value. Assuming %d.\n"),
                             DEFAULT_PRI);
                }
              else
                mres.priority = pri;
              xfree (pristr);
            }

          switch (url_scheme (urlstr))
            {
            case SCHEME_HTTP:
              mres.type = xstrdup ("http");
              break;
#ifdef HAVE_SSL
            case SCHEME_HTTPS:
              mres.type = xstrdup ("https");
              break;
            case SCHEME_FTPS:
              mres.type = xstrdup ("ftps");
              break;
#endif
            case SCHEME_FTP:
              mres.type = xstrdup ("ftp");
              break;
            default:
              DEBUGP (("Unsupported url scheme in %s. Skipping resource.\n", urlstr));
            }

          if (mres.type)
            {
              DEBUGP (("TYPE=%s\n", mres.type));

              /* At this point we have validated the new resource.  */

              find_key_value (url_end, val_end, "geo", &mres.location);

              mres.url = urlstr;
              urlstr = NULL;

              mres.preference = 0;
              if (has_key (url_end, val_end, "pref"))
                {
                  DEBUGP (("This resource has preference\n"));
                  mres.preference = 1;
                }

              /* 1 slot from new resource, 1 slot for null-termination.  */
              mfile->resources = xrealloc (mfile->resources,
                                           sizeof (metalink_resource_t *) * (res_count + 2));
              mfile->resources[res_count] = xnew0 (metalink_resource_t);
              *mfile->resources[res_count] = mres;
              res_count++;
            }
        } /* Handle resource link (rel=duplicate).  */

      /* Handle Metalink/XML resources.  */
      else if (reltype && !strcmp (reltype, "application/metalink4+xml"))
        {
          metalink_metaurl_t murl = {0};
          char *pristr;

          /*
             Valid ranges for the "pri" attribute are from
             1 to 999999.  Mirror servers with a lower value of the "pri"
             attribute have a higher priority, while mirrors with an undefined
             "pri" attribute are considered to have a value of 999999, which is
             the lowest priority.

             rfc6249 section 3.1
           */
          murl.priority = DEFAULT_PRI;
          if (find_key_value (url_end, val_end, "pri", &pristr))
            {
              long pri;
              char *end_pristr;
              /* Do not care for errno since 0 is error in this case.  */
              pri = strtol (pristr, &end_pristr, 10);
              if (end_pristr != pristr + strlen (pristr) ||
                  !VALID_PRI_RANGE (pri))
                {
                  /* This is against the specification, so let's inform the user.  */
                  logprintf (LOG_NOTQUIET,
                             _("Invalid pri value. Assuming %d.\n"),
                             DEFAULT_PRI);
                }
              else
                murl.priority = pri;
              xfree (pristr);
            }

          murl.mediatype = xstrdup (reltype);

          DEBUGP (("MEDIATYPE=%s\n", murl.mediatype));

          /* At this point we have validated the new resource.  */

          find_key_value (url_end, val_end, "name", &murl.name);

          murl.url = urlstr;
          urlstr = NULL;

          /* 1 slot from new resource, 1 slot for null-termination.  */
          mfile->metaurls = xrealloc (mfile->metaurls,
                                       sizeof (metalink_metaurl_t *) * (meta_count + 2));
          mfile->metaurls[meta_count] = xnew0 (metalink_metaurl_t);
          *mfile->metaurls[meta_count] = murl;
          meta_count++;
        } /* Handle resource link (rel=describedby).  */
      else
        DEBUGP (("This link header was not used for Metalink\n"));

      xfree (urlstr);
      xfree (reltype);
      xfree (rel);
    } /* Iterate over link headers.  */

  /* Null-terminate resources array.  */
  mfile->resources[res_count] = 0;
  mfile->metaurls[meta_count] = 0;

  if (res_count == 0 && meta_count == 0)
    {
      DEBUGP (("No valid metalink references found.\n"));
      goto fail;
    }

  /* Find all Digest headers.  */
  for (i = 0;
       (i = resp_header_locate (resp, "Digest", i, &val_beg, &val_end)) != -1;
       i++)
    {
      const char *dig_pos;
      char *dig_type, *dig_hash;

      /* Each Digest header can include multiple hashes. Example:
           Digest: SHA=thvDyvhfIqlvFe+A9MYgxAfm1q5=,unixsum=30637
           Digest: md5=HUXZLQLMuI/KZ5KDcJPcOA==
       */
      for (dig_pos = val_beg;
           (dig_pos = find_key_values (dig_pos, val_end, &dig_type, &dig_hash));
           dig_pos++)
        {
          /* The hash here is assumed to be base64. We need the hash in hex.
             Therefore we convert: base64 -> binary -> hex.  */
          const size_t dig_hash_str_len = strlen (dig_hash);
          char bin_hash[256];
          ssize_t hash_bin_len;

          // there is no hash with that size
          if (dig_hash_str_len >= sizeof (bin_hash))
            {
              DEBUGP (("Hash too long, ignored.\n"));
              xfree (dig_type);
              xfree (dig_hash);
              continue;
            }

          hash_bin_len = wget_base64_decode (dig_hash, bin_hash, dig_hash_str_len * 3 / 4 + 1);

          /* Detect malformed base64 input.  */
          if (hash_bin_len < 0)
            {
              DEBUGP (("Malformed base64 input, ignored.\n"));
              xfree (dig_type);
              xfree (dig_hash);
              continue;
            }

          /* One slot for me, one for zero-termination.  */
          mfile->checksums =
                  xrealloc (mfile->checksums,
                            sizeof (metalink_checksum_t *) * (hash_count + 2));
          mfile->checksums[hash_count] = xnew (metalink_checksum_t);
          mfile->checksums[hash_count]->type = dig_type;

          mfile->checksums[hash_count]->hash = xmalloc ((size_t)hash_bin_len * 2 + 1);
          wg_hex_to_string (mfile->checksums[hash_count]->hash, bin_hash, (size_t)hash_bin_len);

          xfree (dig_hash);

          hash_count++;
        }
    }

  /* Zero-terminate checksums array.  */
  mfile->checksums[hash_count] = 0;

  /*
    If Instance Digests are not provided by the Metalink servers, the
    Link header fields pertaining to this specification MUST be ignored.

    rfc6249 section 6
   */
  if (res_count && hash_count == 0)
    {
      logputs (LOG_VERBOSE,
               _("Could not find acceptable digest for Metalink resources.\n"
                 "Ignoring them.\n"));
      goto fail;
    }

  /* Metalink data is OK. Now we just need to sort the resources based
     on their priorities, preference, and perhaps location.  */
  stable_sort (mfile->resources, res_count, sizeof (metalink_resource_t *), metalink_res_cmp);
  stable_sort (mfile->metaurls, meta_count, sizeof (metalink_metaurl_t *), metalink_meta_cmp);

  /* Restore sensible preference values (in case someone cares to look).  */
  for (i = 0; i < res_count; ++i)
    mfile->resources[i]->preference = 1000000 - mfile->resources[i]->priority;

  metalink = xnew0 (metalink_t);
  metalink->files = xmalloc (sizeof (metalink_file_t *) * 2);
  metalink->files[0] = mfile;
  metalink->files[1] = 0;
  metalink->origin = xstrdup (u->url);
  metalink->version = METALINK_VERSION_4;
  /* Leave other fields set to 0.  */

  return metalink;

fail:
  /* Free all allocated memory.  */
  if (metalink)
    metalink_delete (metalink);
  else
    metalink_file_delete (mfile);
  return NULL;
}
#endif /* HAVE_METALINK */

/* Retrieve a document through HTTP protocol.  It recognizes status
   code, and correctly handles redirections.  It closes the network
   socket.  If it receives an error from the functions below it, it
   will print it if there is enough information to do so (almost
   always), returning the error to the caller (i.e. http_loop).

   Various HTTP parameters are stored to hs.

   If PROXY is non-NULL, the connection will be made to the proxy
   server, and u->url will be requested.  */
static uerr_t
gethttp (const struct url *u, struct url *original_url, struct http_stat *hs,
         int *dt, struct url *proxy, struct iri *iri, int count)
{
  struct request *req = NULL;

  char *type = NULL;
  char *user, *passwd;
  char *proxyauth;
  int statcode;
  int write_error;
  wgint contlen, contrange;
  const struct url *conn;
  FILE *fp;
  int err;
  uerr_t retval;
#ifdef HAVE_HSTS
#ifdef TESTING
  /* we don't link against main.o when we're testing */
  hsts_store_t hsts_store = NULL;
#else
  extern hsts_store_t hsts_store;
#endif
  const char *hsts_params;
  time_t max_age;
  bool include_subdomains;
#endif

  int sock = -1;

  /* Set to 1 when the authorization has already been sent and should
     not be tried again. */
  bool auth_finished = false;

  /* Set to 1 when just globally-set Basic authorization has been sent;
   * should prevent further Basic negotiations, but not other
   * mechanisms. */
  bool basic_auth_finished = false;

  /* Whether NTLM authentication is used for this request. */
  bool ntlm_seen = false;

  /* Whether our connection to the remote host is through SSL.  */
  bool using_ssl = false;

  /* Whether a HEAD request will be issued (as opposed to GET or
     POST). */
  bool head_only = !!(*dt & HEAD_ONLY);

  /* Whether conditional get request will be issued.  */
  bool cond_get = !!(*dt & IF_MODIFIED_SINCE);

#ifdef HAVE_METALINK
  /* Are we looking for metalink info in HTTP headers?  */
  bool metalink = !!(*dt & METALINK_METADATA);
#endif

  char *head = NULL;
  struct response *resp = NULL;
  char hdrval[512];
  char *message = NULL;

  /* Declare WARC variables. */
  bool warc_enabled = (opt.warc_filename != NULL);
  FILE *warc_tmp = NULL;
  char warc_timestamp_str [21];
  char warc_request_uuid [48];
  ip_address warc_ip_buf, *warc_ip = NULL;
  off_t warc_payload_offset = -1;

  /* Whether this connection will be kept alive after the HTTP request
     is done. */
  bool keep_alive;

  /* Is the server using the chunked transfer encoding?  */
  bool chunked_transfer_encoding = false;

  /* Whether keep-alive should be inhibited.  */
  bool inhibit_keep_alive =
    !opt.http_keep_alive || opt.ignore_length;

  /* Headers sent when using POST. */
  wgint body_data_size = 0;

#ifdef HAVE_SSL
  if (u->scheme == SCHEME_HTTPS)
    {
      /* Initialize the SSL context.  After this has once been done,
         it becomes a no-op.  */
      if (!ssl_init ())
        {
          scheme_disable (SCHEME_HTTPS);
          logprintf (LOG_NOTQUIET,
                     _("Disabling SSL due to encountered errors.\n"));
          retval = SSLINITFAILED;
          goto cleanup;
        }
    }
#endif /* HAVE_SSL */

  /* Initialize certain elements of struct http_stat.
   * Since this function is called in a loop, we have to xfree certain
   * members. */
  hs->len = 0;
  hs->contlen = -1;
  hs->res = -1;
  xfree (hs->rderrmsg);
  xfree (hs->newloc);
  xfree (hs->remote_time);
  xfree (hs->error);
  xfree (hs->message);
  hs->local_encoding = ENC_NONE;
  hs->remote_encoding = ENC_NONE;

  conn = u;

  {
    uerr_t ret;
    req = initialize_request (u, hs, dt, proxy, inhibit_keep_alive,
                              &basic_auth_finished, &body_data_size,
                              &user, &passwd, &ret);
    if (req == NULL)
      {
        retval = ret;
        goto cleanup;
      }
  }
 retry_with_auth:
  /* We need to come back here when the initial attempt to retrieve
     without authorization header fails.  (Expected to happen at least
     for the Digest authorization scheme.)  */

  if (opt.cookies)
    request_set_header (req, "Cookie",
                        cookie_header (wget_cookie_jar,
                                       u->host, u->port, u->path,
#ifdef HAVE_SSL
                                       u->scheme == SCHEME_HTTPS
#else
                                       0
#endif
                                       ),
                        rel_value);

  /* Add the user headers. */
  if (opt.user_headers)
    {
      int i;
      for (i = 0; opt.user_headers[i]; i++)
        request_set_user_header (req, opt.user_headers[i]);
    }

  proxyauth = NULL;
  if (proxy)
    {
      conn = proxy;
      initialize_proxy_configuration (u, req, proxy, &proxyauth);
    }
  keep_alive = true;

  /* Establish the connection.  */
  if (inhibit_keep_alive)
    keep_alive = false;

  {
    uerr_t conn_err = establish_connection (u, &conn, hs, proxy, &proxyauth, &req,
                                            &using_ssl, inhibit_keep_alive, &sock);
    if (conn_err != RETROK)
      {
        retval = conn_err;
        goto cleanup;
      }
  }

  /* Open the temporary file where we will write the request. */
  if (warc_enabled)
    {
      warc_tmp = warc_tempfile ();
      if (warc_tmp == NULL)
        {
          CLOSE_INVALIDATE (sock);
          retval = WARC_TMP_FOPENERR;
          goto cleanup;
        }

      if (! proxy)
        {
          warc_ip = &warc_ip_buf;
          socket_ip_address (sock, warc_ip, ENDPOINT_PEER);
        }
    }

  /* Send the request to server.  */
  write_error = request_send (req, sock, warc_tmp);

  if (write_error >= 0)
    {
      if (opt.body_data)
        {
          DEBUGP (("[BODY data: %s]\n", opt.body_data));
          write_error = fd_write (sock, opt.body_data, body_data_size, -1);
          if (write_error >= 0 && warc_tmp != NULL)
            {
              int warc_tmp_written;

              /* Remember end of headers / start of payload. */
              warc_payload_offset = ftello (warc_tmp);

              /* Write a copy of the data to the WARC record. */
              warc_tmp_written = fwrite (opt.body_data, 1, body_data_size, warc_tmp);
              if (warc_tmp_written != body_data_size)
                write_error = -2;
            }
         }
      else if (opt.body_file && body_data_size != 0)
        {
          if (warc_tmp != NULL)
            /* Remember end of headers / start of payload */
            warc_payload_offset = ftello (warc_tmp);

          write_error = body_file_send (sock, opt.body_file, body_data_size, warc_tmp);
        }
    }

  if (write_error < 0)
    {
      CLOSE_INVALIDATE (sock);

      if (warc_tmp != NULL)
        fclose (warc_tmp);

      if (write_error == -2)
        retval = WARC_TMP_FWRITEERR;
      else
        retval = WRITEFAILED;
      goto cleanup;
    }
  logprintf (LOG_VERBOSE, _("%s request sent, awaiting response... "),
             proxy ? "Proxy" : "HTTP");
  contlen = -1;
  contrange = 0;
  *dt &= ~RETROKF;


  if (warc_enabled)
    {
      bool warc_result;

      /* Generate a timestamp and uuid for this request. */
      warc_timestamp (warc_timestamp_str, sizeof (warc_timestamp_str));
      warc_uuid_str (warc_request_uuid, sizeof (warc_request_uuid));

      /* Create a request record and store it in the WARC file. */
      warc_result = warc_write_request_record (u->url, warc_timestamp_str,
                                               warc_request_uuid, warc_ip,
                                               warc_tmp, warc_payload_offset);
      if (! warc_result)
        {
          CLOSE_INVALIDATE (sock);
          retval = WARC_ERR;
          goto cleanup;
        }

      /* warc_write_request_record has also closed warc_tmp. */
    }

  /* Repeat while we receive a 10x response code.  */
  {
    bool _repeat;

    do
      {
        head = read_http_response_head (sock);
        if (!head)
          {
            if (errno == 0)
              {
                logputs (LOG_NOTQUIET, _("No data received.\n"));
                CLOSE_INVALIDATE (sock);
                retval = HEOF;
              }
            else
              {
                logprintf (LOG_NOTQUIET, _("Read error (%s) in headers.\n"),
                           fd_errstr (sock));
                CLOSE_INVALIDATE (sock);
                retval = HERR;
              }
            goto cleanup;
          }
        DEBUGP (("\n---response begin---\n%s---response end---\n", head));

        resp = resp_new (head);

        /* Check for status line.  */
        xfree (message);
        statcode = resp_status (resp, &message);
        if (statcode < 0)
          {
            char *tms = datetime_str (time (NULL));
            logprintf (LOG_VERBOSE, "%d\n", statcode);
            logprintf (LOG_NOTQUIET, _("%s ERROR %d: %s.\n"), tms, statcode,
                       quotearg_style (escape_quoting_style,
                                       _("Malformed status line")));
            CLOSE_INVALIDATE (sock);
            retval = HERR;
            goto cleanup;
          }

        if (H_10X (statcode))
          {
            xfree (head);
            resp_free (&resp);
            _repeat = true;
            DEBUGP (("Ignoring response\n"));
          }
        else
          {
            _repeat = false;
          }
      }
    while (_repeat);
  }

  xfree (hs->message);
  hs->message = xstrdup (message);
  if (!opt.server_response)
    logprintf (LOG_VERBOSE, "%2d %s\n", statcode,
               message ? quotearg_style (escape_quoting_style, message) : "");
  else
    {
      logprintf (LOG_VERBOSE, "\n");
      print_server_response (resp, "  ");
    }

  if (!opt.ignore_length
      && resp_header_copy (resp, "Content-Length", hdrval, sizeof (hdrval)))
    {
      wgint parsed;
      errno = 0;
      parsed = str_to_wgint (hdrval, NULL, 10);
      if (parsed == WGINT_MAX && errno == ERANGE)
        {
          /* Out of range.
             #### If Content-Length is out of range, it most likely
             means that the file is larger than 2G and that we're
             compiled without LFS.  In that case we should probably
             refuse to even attempt to download the file.  */
          contlen = -1;
        }
      else if (parsed < 0)
        {
          /* Negative Content-Length; nonsensical, so we can't
             assume any information about the content to receive. */
          contlen = -1;
        }
      else
        contlen = parsed;
    }

  /* Check for keep-alive related responses. */
  if (!inhibit_keep_alive)
    {
      if (resp_header_copy (resp, "Connection", hdrval, sizeof (hdrval)))
        {
          if (0 == c_strcasecmp (hdrval, "Close"))
            keep_alive = false;
        }
    }

  chunked_transfer_encoding = false;
  if (resp_header_copy (resp, "Transfer-Encoding", hdrval, sizeof (hdrval))
      && 0 == c_strcasecmp (hdrval, "chunked"))
    chunked_transfer_encoding = true;

  /* Handle (possibly multiple instances of) the Set-Cookie header. */
  if (opt.cookies)
    {
      int scpos;
      const char *scbeg, *scend;
      /* The jar should have been created by now. */
      assert (wget_cookie_jar != NULL);
      for (scpos = 0;
           (scpos = resp_header_locate (resp, "Set-Cookie", scpos,
                                        &scbeg, &scend)) != -1;
           ++scpos)
        {
          char buf[1024], *set_cookie;
          size_t len = scend - scbeg;

          if (len < sizeof (buf))
            set_cookie = buf;
          else
            set_cookie = xmalloc (len + 1);

          memcpy (set_cookie, scbeg, len);
          set_cookie[len] = 0;

          cookie_handle_set_cookie (wget_cookie_jar, u->host, u->port,
                                    u->path, set_cookie);

          if (set_cookie != buf)
            xfree (set_cookie);
        }
    }

  if (keep_alive)
    /* The server has promised that it will not close the connection
       when we're done.  This means that we can register it.  */
    register_persistent (conn->host, conn->port, sock, using_ssl);

#ifdef HAVE_METALINK
  /* We need to check for the Metalink data in the very first response
     we get from the server (before redirections, authorization, etc.).  */
  if (metalink)
    {
      hs->metalink = metalink_from_http (resp, hs, u);
      /* Bugfix: hs->local_file is NULL (opt.content_disposition).  */
      if (!hs->local_file && hs->metalink && hs->metalink->origin)
        hs->local_file = xstrdup (hs->metalink->origin);
      xfree (hs->message);
      retval = RETR_WITH_METALINK;
      CLOSE_FINISH (sock);
      goto cleanup;
    }
#endif

  if (statcode == HTTP_STATUS_UNAUTHORIZED)
    {
      /* Authorization is required.  */
      uerr_t auth_err = RETROK;
      bool retry;
      /* Normally we are not interested in the response body.
         But if we are writing a WARC file we are: we like to keep everything.  */
      if (warc_enabled)
        {
          int _err;
          type = resp_header_strdup (resp, "Content-Type");
          _err = read_response_body (hs, sock, NULL, contlen, 0,
                                    chunked_transfer_encoding,
                                    u->url, warc_timestamp_str,
                                    warc_request_uuid, warc_ip, type,
                                    statcode, head);
          xfree (type);

          if (_err != RETRFINISHED || hs->res < 0)
            {
              CLOSE_INVALIDATE (sock);
              retval = _err;
              goto cleanup;
            }
          else
            CLOSE_FINISH (sock);
        }
      else
        {
          /* Since WARC is disabled, we are not interested in the response body.  */
          if (keep_alive && !head_only
              && skip_short_body (sock, contlen, chunked_transfer_encoding))
            CLOSE_FINISH (sock);
          else
            CLOSE_INVALIDATE (sock);
        }

      pconn.authorized = false;

      {
        auth_err = check_auth (u, user, passwd, resp, req,
                               &ntlm_seen, &retry,
                               &basic_auth_finished,
                               &auth_finished);
        if (auth_err == RETROK && retry)
          {
            resp_free (&resp);
            xfree (message);
            xfree (head);
            goto retry_with_auth;
          }
      }
      if (auth_err == RETROK)
        retval = AUTHFAILED;
      else
        retval = auth_err;
      goto cleanup;
    }
  else /* statcode != HTTP_STATUS_UNAUTHORIZED */
    {
      /* Kludge: if NTLM is used, mark the TCP connection as authorized. */
      if (ntlm_seen)
        pconn.authorized = true;
    }

  {
    uerr_t ret = check_file_output (u, hs, resp, hdrval, sizeof hdrval);
    if (ret != RETROK)
      {
        retval = ret;
        goto cleanup;
      }
  }

  hs->statcode = statcode;
  xfree (hs->error);
  if (statcode == -1)
    hs->error = xstrdup (_("Malformed status line"));
  else if (!message || !*message)
    hs->error = xstrdup (_("(no description)"));
  else
    hs->error = xstrdup (message);

#ifdef HAVE_HSTS
  if (opt.hsts && hsts_store)
    {
      hsts_params = resp_header_strdup (resp, "Strict-Transport-Security");
      if (parse_strict_transport_security (hsts_params, &max_age, &include_subdomains))
        {
          /* process strict transport security */
          if (hsts_store_entry (hsts_store, u->scheme, u->host, u->port, max_age, include_subdomains))
            DEBUGP(("Added new HSTS host: %s:%u (max-age: %lu, includeSubdomains: %s)\n",
                   u->host,
                   (unsigned) u->port,
                   (unsigned long) max_age,
                   (include_subdomains ? "true" : "false")));
          else
            DEBUGP(("Updated HSTS host: %s:%u (max-age: %lu, includeSubdomains: %s)\n",
                   u->host,
                   (unsigned) u->port,
                   (unsigned long) max_age,
                   (include_subdomains ? "true" : "false")));
        }
      xfree (hsts_params);
    }
#endif

  type = resp_header_strdup (resp, "Content-Type");
  if (type)
    {
      char *tmp = strchr (type, ';');
      if (tmp)
        {
#ifdef ENABLE_IRI
          /* sXXXav: only needed if IRI support is enabled */
          char *tmp2 = tmp + 1;
#endif

          while (tmp > type && c_isspace (tmp[-1]))
            --tmp;
          *tmp = '\0';

#ifdef ENABLE_IRI
          /* Try to get remote encoding if needed */
          if (opt.enable_iri && !opt.encoding_remote)
            {
              tmp = parse_charset (tmp2);
              if (tmp)
                set_content_encoding (iri, tmp);
              xfree (tmp);
            }
#endif
        }
    }
  xfree (hs->newloc);
  hs->newloc = resp_header_strdup (resp, "Location");
  xfree (hs->remote_time);
  hs->remote_time = resp_header_strdup (resp, "Last-Modified");
  if (!hs->remote_time) // now look for the Wayback Machine's timestamp
    hs->remote_time = resp_header_strdup (resp, "X-Archive-Orig-last-modified");

  if (resp_header_copy (resp, "Content-Range", hdrval, sizeof (hdrval)))
    {
      wgint first_byte_pos, last_byte_pos, entity_length;
      if (parse_content_range (hdrval, &first_byte_pos, &last_byte_pos,
                               &entity_length))
        {
          contrange = first_byte_pos;
          contlen = last_byte_pos - first_byte_pos + 1;
        }
    }

  if (resp_header_copy (resp, "Content-Encoding", hdrval, sizeof (hdrval)))
    {
      hs->local_encoding = ENC_INVALID;

      switch (hdrval[0])
        {
        case 'b': case 'B':
          if (0 == c_strcasecmp(hdrval, "br"))
            hs->local_encoding = ENC_BROTLI;
          break;
        case 'c': case 'C':
          if (0 == c_strcasecmp(hdrval, "compress"))
            hs->local_encoding = ENC_COMPRESS;
          break;
        case 'd': case 'D':
          if (0 == c_strcasecmp(hdrval, "deflate"))
            hs->local_encoding = ENC_DEFLATE;
          break;
        case 'g': case 'G':
          if (0 == c_strcasecmp(hdrval, "gzip"))
            hs->local_encoding = ENC_GZIP;
          break;
        case 'i': case 'I':
          if (0 == c_strcasecmp(hdrval, "identity"))
            hs->local_encoding = ENC_NONE;
          break;
        case 'x': case 'X':
          if (0 == c_strcasecmp(hdrval, "x-compress"))
            hs->local_encoding = ENC_COMPRESS;
          else if (0 == c_strcasecmp(hdrval, "x-gzip"))
            hs->local_encoding = ENC_GZIP;
          break;
        case '\0':
          hs->local_encoding = ENC_NONE;
        }

      if (hs->local_encoding == ENC_INVALID)
        {
          DEBUGP (("Unrecognized Content-Encoding: %s\n", hdrval));
          hs->local_encoding = ENC_NONE;
        }
#ifdef HAVE_LIBZ
      else if (hs->local_encoding == ENC_GZIP
               && opt.compression != compression_none)
        {
          const char *p;

          /* Make sure the Content-Type is not gzip before decompressing */
          if (type)
            {
              p = strchr (type, '/');
              if (p == NULL)
                {
                  hs->remote_encoding = ENC_GZIP;
                  hs->local_encoding = ENC_NONE;
                }
              else
                {
                  p++;
                  if (c_tolower(p[0]) == 'x' && p[1] == '-')
                    p += 2;
                  if (0 != c_strcasecmp (p, "gzip"))
                    {
                      hs->remote_encoding = ENC_GZIP;
                      hs->local_encoding = ENC_NONE;
                    }
                }
            }
          else
            {
               hs->remote_encoding = ENC_GZIP;
               hs->local_encoding = ENC_NONE;
            }

          /* don't uncompress if a file ends with '.gz' or '.tgz' */
          if (hs->remote_encoding == ENC_GZIP
              && (p = strrchr(u->file, '.'))
              && (c_strcasecmp(p, ".gz") == 0 || c_strcasecmp(p, ".tgz") == 0))
            {
               DEBUGP (("Enabling broken server workaround. Will not decompress this GZip file.\n"));
               hs->remote_encoding = ENC_NONE;
            }
        }
#endif
    }

  /* 20x responses are counted among successful by default.  */
  if (H_20X (statcode))
    *dt |= RETROKF;

  if (statcode == HTTP_STATUS_NO_CONTENT)
    {
      /* 204 response has no body (RFC 2616, 4.3) */

      /* In case the caller cares to look...  */
      hs->len = 0;
      hs->res = 0;
      hs->restval = 0;

      CLOSE_FINISH (sock);

      retval = RETRFINISHED;
      goto cleanup;
    }

  /* Return if redirected.  */
  if (H_REDIRECTED (statcode) || statcode == HTTP_STATUS_MULTIPLE_CHOICES)
    {
      /* RFC2068 says that in case of the 300 (multiple choices)
         response, the server can output a preferred URL through
         `Location' header; otherwise, the request should be treated
         like GET.  So, if the location is set, it will be a
         redirection; otherwise, just proceed normally.  */
      if (statcode == HTTP_STATUS_MULTIPLE_CHOICES && !hs->newloc)
        *dt |= RETROKF;
      else
        {
          logprintf (LOG_VERBOSE,
                     _("Location: %s%s\n"),
                     hs->newloc ? escnonprint_uri (hs->newloc) : _("unspecified"),
                     hs->newloc ? _(" [following]") : "");

          /* In case the caller cares to look...  */
          hs->len = 0;
          hs->res = 0;
          hs->restval = 0;

          /* Normally we are not interested in the response body of a redirect.
             But if we are writing a WARC file we are: we like to keep everything.  */
          if (warc_enabled)
            {
              int _err = read_response_body (hs, sock, NULL, contlen, 0,
                                            chunked_transfer_encoding,
                                            u->url, warc_timestamp_str,
                                            warc_request_uuid, warc_ip, type,
                                            statcode, head);

              if (_err != RETRFINISHED || hs->res < 0)
                {
                  CLOSE_INVALIDATE (sock);
                  retval = _err;
                  goto cleanup;
                }
              else
                CLOSE_FINISH (sock);
            }
          else
            {
              /* Since WARC is disabled, we are not interested in the response body.  */
              if (keep_alive && !head_only
                  && skip_short_body (sock, contlen, chunked_transfer_encoding))
                CLOSE_FINISH (sock);
              else
                CLOSE_INVALIDATE (sock);
            }

          /* From RFC2616: The status codes 303 and 307 have
             been added for servers that wish to make unambiguously
             clear which kind of reaction is expected of the client.

             A 307 should be redirected using the same method,
             in other words, a POST should be preserved and not
             converted to a GET in that case.

             With strict adherence to RFC2616, POST requests are not
             converted to a GET request on 301 Permanent Redirect
             or 302 Temporary Redirect.

             A switch may be provided later based on the HTTPbis draft
             that allows clients to convert POST requests to GET
             requests on 301 and 302 response codes. */
          switch (statcode)
            {
            case HTTP_STATUS_TEMPORARY_REDIRECT:
            case HTTP_STATUS_PERMANENT_REDIRECT:
              retval = NEWLOCATION_KEEP_POST;
              goto cleanup;
            case HTTP_STATUS_MOVED_PERMANENTLY:
              if (opt.method && c_strcasecmp (opt.method, "post") != 0)
                {
                  retval = NEWLOCATION_KEEP_POST;
                  goto cleanup;
                }
              break;
            case HTTP_STATUS_MOVED_TEMPORARILY:
              if (opt.method && c_strcasecmp (opt.method, "post") != 0)
                {
                  retval = NEWLOCATION_KEEP_POST;
                  goto cleanup;
                }
              break;
            }
          retval = NEWLOCATION;
          goto cleanup;
        }
    }

  if (cond_get)
    {
      if (statcode == HTTP_STATUS_NOT_MODIFIED)
        {
          logprintf (LOG_VERBOSE,
                     _ ("File %s not modified on server. Omitting download.\n\n"),
                     quote (hs->local_file));
          *dt |= RETROKF;
          CLOSE_FINISH (sock);
          retval = RETRUNNEEDED;
          goto cleanup;
        }
    }

  set_content_type (dt, type);

  if (opt.adjust_extension)
    {
      const char *encoding_ext = NULL;
      switch (hs->local_encoding)
        {
        case ENC_INVALID:
        case ENC_NONE:
          break;
        case ENC_BROTLI:
          encoding_ext = ".br";
          break;
        case ENC_COMPRESS:
          encoding_ext = ".Z";
          break;
        case ENC_DEFLATE:
          encoding_ext = ".zlib";
          break;
        case ENC_GZIP:
          encoding_ext = ".gz";
          break;
        default:
          DEBUGP (("No extension found for encoding %d\n",
                   hs->local_encoding));
      }
      if (encoding_ext != NULL)
        {
          char *file_ext = strrchr (hs->local_file, '.');
          /* strip Content-Encoding extension (it will be re-added later) */
          if (file_ext != NULL && 0 == strcasecmp (file_ext, encoding_ext))
            *file_ext = '\0';
        }
      if (*dt & TEXTHTML)
        /* -E / --adjust-extension / adjust_extension = on was specified,
           and this is a text/html file.  If some case-insensitive
           variation on ".htm[l]" isn't already the file's suffix,
           tack on ".html". */
        {
          ensure_extension (hs, ".html", dt);
        }
      else if (*dt & TEXTCSS)
        {
          ensure_extension (hs, ".css", dt);
        }
      if (encoding_ext != NULL)
        {
          ensure_extension (hs, encoding_ext, dt);
        }
    }

  if (cond_get)
    {
      /* Handle the case when server ignores If-Modified-Since header.  */
      if (statcode == HTTP_STATUS_OK && hs->remote_time)
        {
          time_t tmr = http_atotm (hs->remote_time);

          /* Check if the local file is up-to-date based on Last-Modified header
             and content length.  */
          if (tmr != (time_t) - 1 && tmr <= hs->orig_file_tstamp
              && (contlen == -1 || contlen == hs->orig_file_size))
            {
              logprintf (LOG_VERBOSE,
                         _("Server ignored If-Modified-Since header for file %s.\n"
                           "You might want to add --no-if-modified-since option."
                           "\n\n"),
                         quote (hs->local_file));
              *dt |= RETROKF;
              CLOSE_INVALIDATE (sock);
              retval = RETRUNNEEDED;
              goto cleanup;
            }
        }
    }

  if (statcode == HTTP_STATUS_RANGE_NOT_SATISFIABLE
      || (!opt.timestamping && hs->restval > 0 && statcode == HTTP_STATUS_OK
          && contrange == 0 && contlen >= 0 && hs->restval >= contlen))
    {
      /* If `-c' is in use and the file has been fully downloaded (or
         the remote file has shrunk), Wget effectively requests bytes
         after the end of file and the server response with 416
         (or 200 with a <= Content-Length.  */
      logputs (LOG_VERBOSE, _("\
\n    The file is already fully retrieved; nothing to do.\n\n"));
      /* In case the caller inspects. */
      hs->len = contlen;
      hs->res = 0;
      /* Mark as successfully retrieved. */
      *dt |= RETROKF;

      /* Try to maintain the keep-alive connection. It is often cheaper to
       * consume some bytes which have already been sent than to negotiate
       * a new connection. However, if the body is too large, or we don't
       * care about keep-alive, then simply terminate the connection */
      if (keep_alive &&
          skip_short_body (sock, contlen, chunked_transfer_encoding))
        CLOSE_FINISH (sock);
      else
        CLOSE_INVALIDATE (sock);
      retval = RETRUNNEEDED;
      goto cleanup;
    }
  if ((contrange != 0 && contrange != hs->restval)
      || (H_PARTIAL (statcode) && !contrange && hs->restval))
    {
      /* The Range request was somehow misunderstood by the server.
         Bail out.  */
      CLOSE_INVALIDATE (sock);
      retval = RANGEERR;
      goto cleanup;
    }
  if (contlen == -1)
    hs->contlen = -1;
  /* If the response is gzipped, the uncompressed size is unknown. */
  else if (hs->remote_encoding == ENC_GZIP)
    hs->contlen = -1;
  else
    hs->contlen = contlen + contrange;

  if (opt.verbose)
    {
      if (*dt & RETROKF)
        {
          /* No need to print this output if the body won't be
             downloaded at all, or if the original server response is
             printed.  */
          logputs (LOG_VERBOSE, _("Length: "));
          if (contlen != -1)
            {
              logputs (LOG_VERBOSE, number_to_static_string (contlen + contrange));
              if (contlen + contrange >= 1024)
                logprintf (LOG_VERBOSE, " (%s)",
                           human_readable (contlen + contrange, 10, 1));
              if (contrange)
                {
                  if (contlen >= 1024)
                    logprintf (LOG_VERBOSE, _(", %s (%s) remaining"),
                               number_to_static_string (contlen),
                               human_readable (contlen, 10, 1));
                  else
                    logprintf (LOG_VERBOSE, _(", %s remaining"),
                               number_to_static_string (contlen));
                }
            }
          else
            logputs (LOG_VERBOSE,
                     opt.ignore_length ? _("ignored") : _("unspecified"));
          if (type)
            logprintf (LOG_VERBOSE, " [%s]\n", quotearg_style (escape_quoting_style, type));
          else
            logputs (LOG_VERBOSE, "\n");
        }
    }

  /* Return if we have no intention of further downloading.  */
  if ((!(*dt & RETROKF) && !opt.content_on_error) || head_only || (opt.spider && !opt.recursive))
    {
      /* In case the caller cares to look...  */
      hs->len = 0;
      hs->res = 0;
      hs->restval = 0;

      /* Normally we are not interested in the response body of a error responses.
         But if we are writing a WARC file we are: we like to keep everything.  */
      if (warc_enabled)
        {
          int _err = read_response_body (hs, sock, NULL, contlen, 0,
                                        chunked_transfer_encoding,
                                        u->url, warc_timestamp_str,
                                        warc_request_uuid, warc_ip, type,
                                        statcode, head);

          if (_err != RETRFINISHED || hs->res < 0)
            {
              CLOSE_INVALIDATE (sock);
              retval = _err;
              goto cleanup;
            }

          CLOSE_FINISH (sock);
        }
      else
        {
          /* Since WARC is disabled, we are not interested in the response body.  */
          if (head_only)
            /* Pre-1.10 Wget used CLOSE_INVALIDATE here.  Now we trust the
               servers not to send body in response to a HEAD request, and
               those that do will likely be caught by test_socket_open.
               If not, they can be worked around using
               `--no-http-keep-alive'.  */
            CLOSE_FINISH (sock);
          else if (opt.spider && !opt.recursive)
            /* we just want to see if the page exists - no downloading required */
            CLOSE_INVALIDATE (sock);
          else if (keep_alive
                   && skip_short_body (sock, contlen, chunked_transfer_encoding))
            /* Successfully skipped the body; also keep using the socket. */
            CLOSE_FINISH (sock);
          else
            CLOSE_INVALIDATE (sock);
        }

      if (statcode == HTTP_STATUS_GATEWAY_TIMEOUT)
        retval = GATEWAYTIMEOUT;
      else
        retval = RETRFINISHED;

      goto cleanup;
    }

  err = open_output_stream (hs, count, &fp);
  if (err != RETROK)
    {
      CLOSE_INVALIDATE (sock);
      retval = err;
      goto cleanup;
    }

#ifdef ENABLE_XATTR
  if (opt.enable_xattr)
    {
      if (original_url != u)
        set_file_metadata (u, original_url, fp);
      else
        set_file_metadata (u, NULL, fp);
    }
#endif

  err = read_response_body (hs, sock, fp, contlen, contrange,
                            chunked_transfer_encoding,
                            u->url, warc_timestamp_str,
                            warc_request_uuid, warc_ip, type,
                            statcode, head);

  if (hs->res >= 0)
    CLOSE_FINISH (sock);
  else
    CLOSE_INVALIDATE (sock);

  if (!output_stream)
    fclose (fp);

  retval = err;

  cleanup:
  xfree (head);
  xfree (type);
  xfree (message);
  resp_free (&resp);
  request_free (&req);

  return retval;
}

/* Check whether the supplied HTTP status code is among those
   listed for the --retry-on-http-error option. */
static bool
check_retry_on_http_error (const int statcode)
{
  const char *tok = opt.retry_on_http_error;
  while (tok && *tok)
    {
      if (atoi (tok) == statcode)
        return true;
      if ((tok = strchr (tok, ',')))
        ++tok;
    }
  return false;
}

/* The genuine HTTP loop!  This is the part where the retrieval is
   retried, and retried, and retried, and...  */
uerr_t
http_loop (const struct url *u, struct url *original_url, char **newloc,
           char **local_file, const char *referer, int *dt, struct url *proxy,
           struct iri *iri)
{
  int count;
  bool got_head = false;         /* used for time-stamping and filename detection */
  bool time_came_from_head = false;
  bool got_name = false;
  char *tms;
  const char *tmrate;
  uerr_t err, ret = TRYLIMEXC;
  time_t tmr = -1;               /* remote time-stamp */
  struct http_stat hstat;        /* HTTP status */
  struct stat st;
  bool send_head_first = true;
  bool force_full_retrieve = false;


  /* If we are writing to a WARC file: always retrieve the whole file. */
  if (opt.warc_filename != NULL)
    force_full_retrieve = true;


  /* Assert that no value for *LOCAL_FILE was passed. */
  assert (local_file == NULL || *local_file == NULL);

  /* Set LOCAL_FILE parameter. */
  if (local_file && opt.output_document)
    *local_file = HYPHENP (opt.output_document) ? NULL : xstrdup (opt.output_document);

  /* Reset NEWLOC parameter. */
  *newloc = NULL;

  /* This used to be done in main, but it's a better idea to do it
     here so that we don't go through the hoops if we're just using
     FTP or whatever. */
  if (opt.cookies)
    load_cookies ();

  /* Warn on (likely bogus) wildcard usage in HTTP. */
  if (opt.ftp_glob && has_wildcards_p (u->path))
    logputs (LOG_VERBOSE, _("Warning: wildcards not supported in HTTP.\n"));

  /* Setup hstat struct. */
  xzero (hstat);
  hstat.referer = referer;

  if (opt.output_document)
    {
      hstat.local_file = xstrdup (opt.output_document);
      got_name = true;
    }
  else if (!opt.content_disposition)
    {
      hstat.local_file =
        url_file_name (opt.trustservernames ? u : original_url, NULL);
      got_name = true;
    }

  if (got_name && file_exists_p (hstat.local_file, NULL) && opt.noclobber && !opt.output_document)
    {
      /* If opt.noclobber is turned on and file already exists, do not
         retrieve the file. But if the output_document was given, then this
         test was already done and the file didn't exist. Hence the !opt.output_document */
      get_file_flags (hstat.local_file, dt);
      ret = RETROK;
      goto exit;
    }

  /* Reset the counter. */
  count = 0;

  /* Reset the document type. */
  *dt = 0;

  /* Skip preliminary HEAD request if we're not in spider mode.  */
  if (!opt.spider)
    send_head_first = false;

  /* Send preliminary HEAD request if --content-disposition and -c are used
     together.  */
  if (opt.content_disposition && opt.always_rest)
    send_head_first = true;

#ifdef HAVE_METALINK
  if (opt.metalink_over_http)
    {
      *dt |= METALINK_METADATA;
      send_head_first = true;
    }
#endif

  if (opt.timestamping)
    {
      /* Use conditional get request if requested
       * and if timestamp is known at this moment.  */
      if (opt.if_modified_since && !send_head_first && got_name && file_exists_p (hstat.local_file, NULL))
        {
          *dt |= IF_MODIFIED_SINCE;
          {
            uerr_t timestamp_err = set_file_timestamp (&hstat);
            if (timestamp_err != RETROK)
              return timestamp_err;
          }
        }
        /* Send preliminary HEAD request if -N is given and we have existing
         * destination file or content disposition is enabled.  */
      else if (opt.content_disposition || file_exists_p (hstat.local_file, NULL))
        send_head_first = true;
    }

  /* THE loop */
  do
    {
      /* Increment the pass counter.  */
      ++count;
      sleep_between_retrievals (count);

      /* Get the current time string.  */
      tms = datetime_str (time (NULL));

      if (opt.spider && !got_head)
        logprintf (LOG_VERBOSE,
			  _("Spider mode enabled. Check if remote file exists.\n"));

      /* Print fetch message, if opt.verbose.  */
      if (opt.verbose)
        {
          char *hurl = url_string (u, URL_AUTH_HIDE_PASSWD);

          if (count > 1)
            {
              char tmp[256];
              sprintf (tmp, _("(try:%2d)"), count);
              logprintf (LOG_NOTQUIET, "--%s--  %s  %s\n",
                         tms, tmp, hurl);
            }
          else
            {
              logprintf (LOG_NOTQUIET, "--%s--  %s\n",
                         tms, hurl);
            }

#ifdef WINDOWS
          ws_changetitle (hurl);
#endif
          xfree (hurl);
        }

      /* Default document type is empty.  However, if spider mode is
         on or time-stamping is employed, HEAD_ONLY commands is
         encoded within *dt.  */
      if (send_head_first && !got_head)
        *dt |= HEAD_ONLY;
      else
        *dt &= ~HEAD_ONLY;

      /* Decide whether or not to restart.  */
      if (force_full_retrieve)
        hstat.restval = hstat.len;
      else if (opt.start_pos >= 0)
        hstat.restval = opt.start_pos;
      else if (opt.always_rest
          && got_name
          && stat (hstat.local_file, &st) == 0
          && S_ISREG (st.st_mode))
        /* When -c is used, continue from on-disk size.  (Can't use
           hstat.len even if count>1 because we don't want a failed
           first attempt to clobber existing data.)  */
        hstat.restval = st.st_size;
      else if (count > 1)
        {
          /* otherwise, continue where the previous try left off */
          if (hstat.len < hstat.restval)
            hstat.restval -= hstat.len;
          else
            hstat.restval = hstat.len;
        }
      else
        hstat.restval = 0;

      /* Decide whether to send the no-cache directive.  We send it in
         two cases:
           a) we're using a proxy, and we're past our first retrieval.
              Some proxies are notorious for caching incomplete data, so
              we require a fresh get.
           b) caching is explicitly inhibited. */
      if ((proxy && count > 1)        /* a */
          || !opt.allow_cache)        /* b */
        *dt |= SEND_NOCACHE;
      else
        *dt &= ~SEND_NOCACHE;

      /* Try fetching the document, or at least its head.  */
      err = gethttp (u, original_url, &hstat, dt, proxy, iri, count);

      /* Time?  */
      tms = datetime_str (time (NULL));

      /* Get the new location (with or without the redirection).  */
      if (hstat.newloc)
        *newloc = xstrdup (hstat.newloc);

      switch (err)
        {
        case HERR: case HEOF: case CONSOCKERR:
        case CONERROR: case READERR: case WRITEFAILED:
        case RANGEERR: case FOPEN_EXCL_ERR: case GATEWAYTIMEOUT:
          /* Non-fatal errors continue executing the loop, which will
             bring them to "while" statement at the end, to judge
             whether the number of tries was exceeded.  */
          printwhat (count, opt.ntry);
          continue;
        case FWRITEERR: case FOPENERR:
          /* Another fatal error.  */
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("Cannot write to %s (%s).\n"),
                     quote (hstat.local_file), strerror (errno));
          ret = err;
          goto exit;
        case HOSTERR:
          /* Fatal unless option set otherwise. */
          if ( opt.retry_on_host_error )
            {
              printwhat (count, opt.ntry);
              continue;
            }
          ret = err;
          goto exit;
        case CONIMPOSSIBLE: case PROXERR: case SSLINITFAILED:
        case CONTNOTSUPPORTED: case VERIFCERTERR: case FILEBADFILE:
        case UNKNOWNATTR:
          /* Fatal errors just return from the function.  */
          ret = err;
          goto exit;
        case ATTRMISSING:
          /* A missing attribute in a Header is a fatal Protocol error. */
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("Required attribute missing from Header received.\n"));
          ret = err;
          goto exit;
        case AUTHFAILED:
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("Username/Password Authentication Failed.\n"));
          ret = err;
          goto exit;
        case WARC_ERR:
          /* A fatal WARC error. */
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("Cannot write to WARC file.\n"));
          ret = err;
          goto exit;
        case WARC_TMP_FOPENERR: case WARC_TMP_FWRITEERR:
          /* A fatal WARC error. */
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("Cannot write to temporary WARC file.\n"));
          ret = err;
          goto exit;
        case CONSSLERR:
          /* Another fatal error.  */
          logprintf (LOG_NOTQUIET, _("Unable to establish SSL connection.\n"));
          ret = err;
          goto exit;
        case UNLINKERR:
          /* Another fatal error.  */
          logputs (LOG_VERBOSE, "\n");
          logprintf (LOG_NOTQUIET, _("Cannot unlink %s (%s).\n"),
                     quote (hstat.local_file), strerror (errno));
          ret = err;
          goto exit;
        case NEWLOCATION:
        case NEWLOCATION_KEEP_POST:
          /* Return the new location to the caller.  */
          if (!*newloc)
            {
              logprintf (LOG_NOTQUIET,
                         _("ERROR: Redirection (%d) without location.\n"),
                         hstat.statcode);
              ret = WRONGCODE;
            }
          else
            {
              ret = err;
            }
          goto exit;
        case RETRUNNEEDED:
          /* The file was already fully retrieved. */
          ret = RETROK;
          goto exit;
        case RETRFINISHED:
          /* Deal with you later.  */
          break;
#ifdef HAVE_METALINK
        case RETR_WITH_METALINK:
          {
            if (hstat.metalink == NULL)
              {
                logputs (LOG_NOTQUIET,
                         _("Could not find Metalink data in HTTP response. "
                           "Downloading file using HTTP GET.\n"));
                *dt &= ~METALINK_METADATA;
                *dt &= ~HEAD_ONLY;
                got_head = true;
                continue;
              }

            logputs (LOG_VERBOSE,
                     _("Metalink headers found. "
                       "Switching to Metalink mode.\n"));

            ret = retrieve_from_metalink (hstat.metalink);
            goto exit;
          }
          break;
#endif
        default:
          /* All possibilities should have been exhausted.  */
          abort ();
        }

      if (!(*dt & RETROKF))
        {
          char *hurl = NULL;
          if (!opt.verbose)
            {
              /* #### Ugly ugly ugly! */
              hurl = url_string (u, URL_AUTH_HIDE_PASSWD);
              logprintf (LOG_NONVERBOSE, "%s:\n", hurl);
            }

          /* Fall back to GET if HEAD fails with a 500 or 501 error code. */
          if (*dt & HEAD_ONLY
              && (hstat.statcode == 500 || hstat.statcode == 501))
            {
              got_head = true;
              xfree (hurl);
              continue;
            }
          /* Maybe we should always keep track of broken links, not just in
           * spider mode.
           * Don't log error if it was UTF-8 encoded because we will try
           * once unencoded. */
          else if (opt.spider && !iri->utf8_encode)
            {
              /* #### Again: ugly ugly ugly! */
              if (!hurl)
                hurl = url_string (u, URL_AUTH_HIDE_PASSWD);
              nonexisting_url (hurl);
              logprintf (LOG_NOTQUIET, _("\
Remote file does not exist -- broken link!!!\n"));
            }
          else if (check_retry_on_http_error (hstat.statcode))
            {
              printwhat (count, opt.ntry);
              xfree (hurl);
              continue;
            }
          else
            {
              logprintf (LOG_NOTQUIET, _("%s ERROR %d: %s.\n"),
                         tms, hstat.statcode,
                         quotearg_style (escape_quoting_style, hstat.error));
            }
          logputs (LOG_VERBOSE, "\n");
          ret = WRONGCODE;
          xfree (hurl);
          goto exit;
        }

      /* Did we get the time-stamp? */
      if (!got_head || (opt.spider && !opt.recursive))
        {
          got_head = true;    /* no more time-stamping */

          if (opt.timestamping && !hstat.remote_time)
            {
              logputs (LOG_NOTQUIET, _("\
Last-modified header missing -- time-stamps turned off.\n"));
            }
          else if (hstat.remote_time)
            {
              /* Convert the date-string into struct tm.  */
              tmr = http_atotm (hstat.remote_time);
              if (tmr == (time_t) (-1))
                logputs (LOG_VERBOSE, _("\
Last-modified header invalid -- time-stamp ignored.\n"));
              if (*dt & HEAD_ONLY)
                time_came_from_head = true;
            }

          if (send_head_first)
            {
              /* The time-stamping section.  */
              if (opt.timestamping)
                {
                  if (hstat.orig_file_name) /* Perform the following
                                               checks only if the file
                                               we're supposed to
                                               download already exists.  */
                    {
                      if (hstat.remote_time &&
                          tmr != (time_t) (-1))
                        {
                          /* Now time-stamping can be used validly.
                             Time-stamping means that if the sizes of
                             the local and remote file match, and local
                             file is newer than the remote file, it will
                             not be retrieved.  Otherwise, the normal
                             download procedure is resumed.  */
                          if (hstat.orig_file_tstamp >= tmr)
                            {
                              if (hstat.contlen == -1
                                  || hstat.orig_file_size == hstat.contlen)
                                {
                                  logprintf (LOG_VERBOSE, _("\
Server file no newer than local file %s -- not retrieving.\n\n"),
                                             quote (hstat.orig_file_name));
                                  ret = RETROK;
                                  goto exit;
                                }
                              else
                                {
                                  logprintf (LOG_VERBOSE, _("\
The sizes do not match (local %s) -- retrieving.\n"),
                                             number_to_static_string (hstat.orig_file_size));
                                }
                            }
                          else
                            {
                              force_full_retrieve = true;
                              logputs (LOG_VERBOSE,
                                       _("Remote file is newer, retrieving.\n"));
                            }

                          logputs (LOG_VERBOSE, "\n");
                        }
                    }

                  /* free_hstat (&hstat); */
                  hstat.timestamp_checked = true;
                }

              if (opt.spider)
                {
                  bool finished = true;
                  if (opt.recursive)
                    {
                      if ((*dt & TEXTHTML) || (*dt & TEXTCSS))
                        {
                          logputs (LOG_VERBOSE, _("\
Remote file exists and could contain links to other resources -- retrieving.\n\n"));
                          finished = false;
                        }
                      else
                        {
                          logprintf (LOG_VERBOSE, _("\
Remote file exists but does not contain any link -- not retrieving.\n\n"));
                          ret = RETROK; /* RETRUNNEEDED is not for caller. */
                        }
                    }
                  else
                    {
                      if ((*dt & TEXTHTML) || (*dt & TEXTCSS))
                        {
                          logprintf (LOG_VERBOSE, _("\
Remote file exists and could contain further links,\n\
but recursion is disabled -- not retrieving.\n\n"));
                        }
                      else
                        {
                          logprintf (LOG_VERBOSE, _("\
Remote file exists.\n\n"));
                        }
                      ret = RETROK; /* RETRUNNEEDED is not for caller. */
                    }

                  if (finished)
                    {
                      logprintf (LOG_NONVERBOSE,
                                 _("%s URL: %s %2d %s\n"),
                                 tms, u->url, hstat.statcode,
                                 hstat.message ? quotearg_style (escape_quoting_style, hstat.message) : "");
                      goto exit;
                    }
                }

              got_name = true;
              *dt &= ~HEAD_ONLY;
              count = 0;          /* the retrieve count for HEAD is reset */
              continue;
            } /* send_head_first */
        } /* !got_head */

      if (opt.useservertimestamps
          && (tmr != (time_t) (-1))
          && ((hstat.len == hstat.contlen) ||
              ((hstat.res == 0) && (hstat.contlen == -1))))
        {
          const char *fl = NULL;
          set_local_file (&fl, hstat.local_file);
          if (fl)
            {
              time_t newtmr = -1;
              /* Reparse time header, in case it's changed. */
              if (time_came_from_head
                  && hstat.remote_time && hstat.remote_time[0])
                {
                  newtmr = http_atotm (hstat.remote_time);
                  if (newtmr != (time_t)-1)
                    tmr = newtmr;
                }
              touch (fl, tmr);
            }
        }
      /* End of time-stamping section. */

      tmrate = retr_rate (hstat.rd_size, hstat.dltime);
      total_download_time += hstat.dltime;

      if (hstat.len == hstat.contlen)
        {
          if (*dt & RETROKF || opt.content_on_error)
            {
              bool write_to_stdout = (opt.output_document && HYPHENP (opt.output_document));

              logprintf (LOG_VERBOSE,
                         write_to_stdout
                         ? _("%s (%s) - written to stdout %s[%s/%s]\n\n")
                         : _("%s (%s) - %s saved [%s/%s]\n\n"),
                         tms, tmrate,
                         write_to_stdout ? "" : quote (hstat.local_file),
                         number_to_static_string (hstat.len),
                         number_to_static_string (hstat.contlen));
              logprintf (LOG_NONVERBOSE,
                         "%s URL:%s [%s/%s] -> \"%s\" [%d]\n",
                         tms, u->url,
                         number_to_static_string (hstat.len),
                         number_to_static_string (hstat.contlen),
                         hstat.local_file, count);
            }
          ++numurls;
          total_downloaded_bytes += hstat.rd_size;

          /* Remember that we downloaded the file for later ".orig" code. */
          if (*dt & ADDED_HTML_EXTENSION)
            downloaded_file (FILE_DOWNLOADED_AND_HTML_EXTENSION_ADDED, hstat.local_file);
          else
            downloaded_file (FILE_DOWNLOADED_NORMALLY, hstat.local_file);

          ret = RETROK;
          goto exit;
        }
      else if (hstat.res == 0) /* No read error */
        {
          if (hstat.contlen == -1)  /* We don't know how much we were supposed
                                       to get, so assume we succeeded. */
            {
              if (*dt & RETROKF || opt.content_on_error)
                {
                  bool write_to_stdout = (opt.output_document && HYPHENP (opt.output_document));

                  logprintf (LOG_VERBOSE,
                             write_to_stdout
                             ? _("%s (%s) - written to stdout %s[%s]\n\n")
                             : _("%s (%s) - %s saved [%s]\n\n"),
                             tms, tmrate,
                             write_to_stdout ? "" : quote (hstat.local_file),
                             number_to_static_string (hstat.len));
                  logprintf (LOG_NONVERBOSE,
                             "%s URL:%s [%s] -> \"%s\" [%d]\n",
                             tms, u->url, number_to_static_string (hstat.len),
                             hstat.local_file, count);
                }
              ++numurls;
              total_downloaded_bytes += hstat.rd_size;

              /* Remember that we downloaded the file for later ".orig" code. */
              if (*dt & ADDED_HTML_EXTENSION)
                downloaded_file (FILE_DOWNLOADED_AND_HTML_EXTENSION_ADDED, hstat.local_file);
              else
                downloaded_file (FILE_DOWNLOADED_NORMALLY, hstat.local_file);

              ret = RETROK;
              goto exit;
            }
          else if (hstat.len < hstat.contlen) /* meaning we lost the
                                                 connection too soon */
            {
              logprintf (LOG_VERBOSE,
                         _("%s (%s) - Connection closed at byte %s. "),
                         tms, tmrate, number_to_static_string (hstat.len));
              printwhat (count, opt.ntry);
              continue;
            }
          else if (hstat.len != hstat.restval)
            /* Getting here would mean reading more data than
               requested with content-length, which we never do.  */
            abort ();
          else
            {
              /* Getting here probably means that the content-length was
               * _less_ than the original, local size. We should probably
               * truncate or re-read, or something. FIXME */
              ret = RETROK;
              goto exit;
            }
        }
      else /* from now on hstat.res can only be -1 */
        {
          if (hstat.contlen == -1)
            {
              logprintf (LOG_VERBOSE,
                         _("%s (%s) - Read error at byte %s (%s)."),
                         tms, tmrate, number_to_static_string (hstat.len),
                         hstat.rderrmsg);
              printwhat (count, opt.ntry);
              continue;
            }
          else /* hstat.res == -1 and contlen is given */
            {
              logprintf (LOG_VERBOSE,
                         _("%s (%s) - Read error at byte %s/%s (%s). "),
                         tms, tmrate,
                         number_to_static_string (hstat.len),
                         number_to_static_string (hstat.contlen),
                         hstat.rderrmsg);
              printwhat (count, opt.ntry);
              continue;
            }
        }
      /* not reached */
    }
  while (!opt.ntry || (count < opt.ntry));

exit:
  if ((ret == RETROK || opt.content_on_error) && local_file)
    {
      xfree (*local_file);
      /* Bugfix: Prevent SIGSEGV when hstat.local_file was left NULL
         (i.e. due to opt.content_disposition).  */
      if (hstat.local_file)
        {
          *local_file = hstat.local_file;
          hstat.local_file = NULL;
        }
    }
  free_hstat (&hstat);

  return ret;
}

/* Check whether the result of strptime() indicates success.
   strptime() returns the pointer to how far it got to in the string.
   The processing has been successful if the string is at `GMT' or
   `+X', or at the end of the string.

   In extended regexp parlance, the function returns 1 if P matches
   "^ *(GMT|[+-][0-9]|$)", 0 otherwise.  P being NULL (which strptime
   can return) is considered a failure and 0 is returned.  */
static bool
check_end (const char *p)
{
  if (!p)
    return false;
  while (c_isspace (*p))
    ++p;
  if (!*p
      || (p[0] == 'G' && p[1] == 'M' && p[2] == 'T')
      || ((p[0] == '+' || p[0] == '-') && c_isdigit (p[1])))
    return true;
  else
    return false;
}

/* Convert the textual specification of time in TIME_STRING to the
   number of seconds since the Epoch.

   TIME_STRING can be in any of the three formats RFC2616 allows the
   HTTP servers to emit -- RFC1123-date, RFC850-date or asctime-date,
   as well as the time format used in the Set-Cookie header.
   Timezones are ignored, and should be GMT.

   Return the computed time_t representation, or -1 if the conversion
   fails.

   This function uses strptime with various string formats for parsing
   TIME_STRING.  This results in a parser that is not as lenient in
   interpreting TIME_STRING as I would like it to be.  Being based on
   strptime, it always allows shortened months, one-digit days, etc.,
   but due to the multitude of formats in which time can be
   represented, an ideal HTTP time parser would be even more
   forgiving.  It should completely ignore things like week days and
   concentrate only on the various forms of representing years,
   months, days, hours, minutes, and seconds.  For example, it would
   be nice if it accepted ISO 8601 out of the box.

   I've investigated free and PD code for this purpose, but none was
   usable.  getdate was big and unwieldy, and had potential copyright
   issues, or so I was informed.  Dr. Marcus Hennecke's atotm(),
   distributed with phttpd, is excellent, but we cannot use it because
   it is not assigned to the FSF.  So I stuck it with strptime.  */

time_t
http_atotm (const char *time_string)
{
  /* NOTE: Solaris strptime man page claims that %n and %t match white
     space, but that's not universally available.  Instead, we simply
     use ` ' to mean "skip all WS", which works under all strptime
     implementations I've tested.  */

  static const char *time_formats[] = {
    "%a, %d %b %Y %T",          /* rfc1123: Thu, 29 Jan 1998 22:12:57 */
    "%A, %d-%b-%y %T",          /* rfc850:  Thursday, 29-Jan-98 22:12:57 */
    "%a %b %d %T %Y",           /* asctime: Thu Jan 29 22:12:57 1998 */
    "%a, %d-%b-%Y %T"           /* cookies: Thu, 29-Jan-1998 22:12:57
                                   (used in Set-Cookie, defined in the
                                   Netscape cookie specification.) */
  };
  const char *oldlocale;
  char savedlocale[256];
  size_t i;
  time_t ret = (time_t) -1;

  /* Solaris strptime fails to recognize English month names in
     non-English locales, which we work around by temporarily setting
     locale to C before invoking strptime.  */
  oldlocale = setlocale (LC_TIME, NULL);
  if (oldlocale)
    {
      size_t l = strlen (oldlocale) + 1;
      if (l >= sizeof savedlocale)
        savedlocale[0] = '\0';
      else
        memcpy (savedlocale, oldlocale, l);
    }
  else savedlocale[0] = '\0';

  setlocale (LC_TIME, "C");

  for (i = 0; i < countof (time_formats); i++)
    {
      struct tm t;

      /* Some versions of strptime use the existing contents of struct
         tm to recalculate the date according to format.  Zero it out
         to prevent stack garbage from influencing strptime.  */
      xzero (t);

      if (check_end (strptime (time_string, time_formats[i], &t)))
        {
          ret = timegm (&t);
          break;
        }
    }

  /* Restore the previous locale. */
  if (savedlocale[0])
    setlocale (LC_TIME, savedlocale);

  return ret;
}

/* Authorization support: We support three authorization schemes:

   * `Basic' scheme, consisting of base64-ing USER:PASSWORD string;

   * `Digest' scheme, added by Junio Hamano <junio@twinsun.com>,
   consisting of answering to the server's challenge with the proper
   MD5 digests.

   * `NTLM' ("NT Lan Manager") scheme, based on code written by Daniel
   Stenberg for libcurl.  Like digest, NTLM is based on a
   challenge-response mechanism, but unlike digest, it is non-standard
   (authenticates TCP connections rather than requests), undocumented
   and Microsoft-specific.  */

/* Create the authentication header contents for the `Basic' scheme.
   This is done by encoding the string "USER:PASS" to base64 and
   prepending the string "Basic " in front of it.  */

static char *
basic_authentication_encode (const char *user, const char *passwd)
{
  char buf_t1[256], buf_t2[256];
  char *t1, *t2, *ret;
  size_t len1 = strlen (user) + 1 + strlen (passwd);

  if (len1 < sizeof (buf_t1))
    t1 = buf_t1;
  else
    t1 = xmalloc(len1 + 1);

  if (BASE64_LENGTH (len1) < sizeof (buf_t2))
    t2 = buf_t2;
  else
    t2 = xmalloc (BASE64_LENGTH (len1) + 1);

  sprintf (t1, "%s:%s", user, passwd);
  wget_base64_encode (t1, len1, t2);

  ret = concat_strings ("Basic ", t2, (char *) 0);

  if (t2 != buf_t2)
    xfree (t2);

  if (t1 != buf_t1)
    xfree (t1);

  return ret;
}

#define SKIP_WS(x) do {                         \
  while (c_isspace (*(x)))                        \
    ++(x);                                      \
} while (0)

#ifdef ENABLE_DIGEST
/* Dump the hexadecimal representation of HASH to BUF.  HASH should be
   an array of 16 bytes containing the hash keys, and BUF should be a
   buffer of 33 writable characters (32 for hex digits plus one for
   zero termination).  */
static void
dump_hash (char *buf, const unsigned char *hash)
{
  int i;

  for (i = 0; i < MD5_DIGEST_SIZE; i++, hash++)
    {
      *buf++ = XNUM_TO_digit (*hash >> 4);
      *buf++ = XNUM_TO_digit (*hash & 0xf);
    }
  *buf = '\0';
}

/* Take the line apart to find the challenge, and compose a digest
   authorization header.  See RFC2069 section 2.1.2.  */
static char *
digest_authentication_encode (const char *au, const char *user,
                              const char *passwd, const char *method,
                              const char *path, uerr_t *auth_err)
{
  static char *realm, *opaque, *nonce, *qop, *algorithm;
  static struct {
    const char *name;
    char **variable;
  } options[] = {
    { "realm", &realm },
    { "opaque", &opaque },
    { "nonce", &nonce },
    { "qop", &qop },
    { "algorithm", &algorithm }
  };
  char cnonce[16] = "";
  char *res = NULL;
  int res_len;
  size_t res_size;
  param_token name, value;


  realm = opaque = nonce = algorithm = qop = NULL;

  au += 6;                      /* skip over `Digest' */
  while (extract_param (&au, &name, &value, ',', NULL))
    {
      size_t i;
      size_t namelen = name.e - name.b;
      for (i = 0; i < countof (options); i++)
        if (namelen == strlen (options[i].name)
            && 0 == strncmp (name.b, options[i].name,
                             namelen))
          {
            *options[i].variable = strdupdelim (value.b, value.e);
            break;
          }
    }

  if (qop && strcmp (qop, "auth"))
    {
      logprintf (LOG_NOTQUIET, _("Unsupported quality of protection '%s'.\n"), qop);
      xfree (qop); /* force freeing mem and continue */
    }
  else if (algorithm && strcmp (algorithm,"MD5") && strcmp (algorithm,"MD5-sess"))
    {
      logprintf (LOG_NOTQUIET, _("Unsupported algorithm '%s'.\n"), algorithm);
      xfree (algorithm); /* force freeing mem and continue */
    }

  if (!realm || !nonce || !user || !passwd || !path || !method)
    {
      *auth_err = ATTRMISSING;
      goto cleanup;
   }

  /* Calculate the digest value.  */
  {
    struct md5_ctx ctx;
    unsigned char hash[MD5_DIGEST_SIZE];
    char a1buf[MD5_DIGEST_SIZE * 2 + 1], a2buf[MD5_DIGEST_SIZE * 2 + 1];
    char response_digest[MD5_DIGEST_SIZE * 2 + 1];

    /* A1BUF = H(user ":" realm ":" password) */
    md5_init_ctx (&ctx);
    md5_process_bytes ((unsigned char *)user, strlen (user), &ctx);
    md5_process_bytes ((unsigned char *)":", 1, &ctx);
    md5_process_bytes ((unsigned char *)realm, strlen (realm), &ctx);
    md5_process_bytes ((unsigned char *)":", 1, &ctx);
    md5_process_bytes ((unsigned char *)passwd, strlen (passwd), &ctx);
    md5_finish_ctx (&ctx, hash);

    dump_hash (a1buf, hash);

    if (algorithm && !strcmp (algorithm, "MD5-sess"))
      {
        /* A1BUF = H( H(user ":" realm ":" password) ":" nonce ":" cnonce ) */
        snprintf (cnonce, sizeof (cnonce), "%08x",
          (unsigned) random_number (INT_MAX));

        md5_init_ctx (&ctx);
        /* md5_process_bytes (hash, MD5_DIGEST_SIZE, &ctx); */
        md5_process_bytes (a1buf, MD5_DIGEST_SIZE * 2, &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)nonce, strlen (nonce), &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)cnonce, strlen (cnonce), &ctx);
        md5_finish_ctx (&ctx, hash);

        dump_hash (a1buf, hash);
      }

    /* A2BUF = H(method ":" path) */
    md5_init_ctx (&ctx);
    md5_process_bytes ((unsigned char *)method, strlen (method), &ctx);
    md5_process_bytes ((unsigned char *)":", 1, &ctx);
    md5_process_bytes ((unsigned char *)path, strlen (path), &ctx);
    md5_finish_ctx (&ctx, hash);
    dump_hash (a2buf, hash);

    if (qop && !strcmp (qop, "auth"))
      {
        /* RFC 2617 Digest Access Authentication */
        /* generate random hex string */
        if (!*cnonce)
          snprintf (cnonce, sizeof (cnonce), "%08x",
            (unsigned) random_number (INT_MAX));

        /* RESPONSE_DIGEST = H(A1BUF ":" nonce ":" noncecount ":" clientnonce ":" qop ": " A2BUF) */
        md5_init_ctx (&ctx);
        md5_process_bytes ((unsigned char *)a1buf, MD5_DIGEST_SIZE * 2, &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)nonce, strlen (nonce), &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)"00000001", 8, &ctx); /* TODO: keep track of server nonce values */
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)cnonce, strlen (cnonce), &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)qop, strlen (qop), &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)a2buf, MD5_DIGEST_SIZE * 2, &ctx);
        md5_finish_ctx (&ctx, hash);
      }
    else
      {
        /* RFC 2069 Digest Access Authentication */
        /* RESPONSE_DIGEST = H(A1BUF ":" nonce ":" A2BUF) */
        md5_init_ctx (&ctx);
        md5_process_bytes ((unsigned char *)a1buf, MD5_DIGEST_SIZE * 2, &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)nonce, strlen (nonce), &ctx);
        md5_process_bytes ((unsigned char *)":", 1, &ctx);
        md5_process_bytes ((unsigned char *)a2buf, MD5_DIGEST_SIZE * 2, &ctx);
        md5_finish_ctx (&ctx, hash);
      }

    dump_hash (response_digest, hash);

    res_size = strlen (user)
             + strlen (realm)
             + strlen (nonce)
             + strlen (path)
             + 2 * MD5_DIGEST_SIZE /*strlen (response_digest)*/
             + (opaque ? strlen (opaque) : 0)
             + (algorithm ? strlen (algorithm) : 0)
             + (qop ? 128: 0)
             + strlen (cnonce)
             + 128;

    res = xmalloc (res_size);

    if (qop && !strcmp (qop, "auth"))
      {
        res_len = snprintf (res, res_size, "Digest "\
                "username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", response=\"%s\""\
                ", qop=auth, nc=00000001, cnonce=\"%s\"",
                  user, realm, nonce, path, response_digest, cnonce);

      }
    else
      {
        res_len = snprintf (res, res_size, "Digest "\
                "username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", response=\"%s\"",
                  user, realm, nonce, path, response_digest);
      }

    if (opaque)
      {
        res_len += snprintf (res + res_len, res_size - res_len, ", opaque=\"%s\"", opaque);
      }

    if (algorithm)
      {
        snprintf (res + res_len, res_size - res_len, ", algorithm=\"%s\"", algorithm);
      }
  }

cleanup:
  xfree (realm);
  xfree (opaque);
  xfree (nonce);
  xfree (qop);
  xfree (algorithm);

  return res;
}
#endif /* ENABLE_DIGEST */

/* Computing the size of a string literal must take into account that
   value returned by sizeof includes the terminating \0.  */
#define STRSIZE(literal) (sizeof (literal) - 1)

/* Whether chars in [b, e) begin with the literal string provided as
   first argument and are followed by whitespace or terminating \0.
   The comparison is case-insensitive.  */
#define STARTS(literal, b, e)                           \
  ((e > b) \
   && ((size_t) ((e) - (b))) >= STRSIZE (literal)   \
   && 0 == c_strncasecmp (b, literal, STRSIZE (literal))  \
   && ((size_t) ((e) - (b)) == STRSIZE (literal)          \
       || c_isspace (b[STRSIZE (literal)])))

static bool
known_authentication_scheme_p (const char *hdrbeg, const char *hdrend)
{
  return STARTS ("Basic", hdrbeg, hdrend)
#ifdef ENABLE_DIGEST
    || STARTS ("Digest", hdrbeg, hdrend)
#endif
#ifdef ENABLE_NTLM
    || STARTS ("NTLM", hdrbeg, hdrend)
#endif
    ;
}

#undef STARTS

/* Create the HTTP authorization request header.  When the
   `WWW-Authenticate' response header is seen, according to the
   authorization scheme specified in that header (`Basic' and `Digest'
   are supported by the current implementation), produce an
   appropriate HTTP authorization request header.  */
static char *
create_authorization_line (const char *au, const char *user,
                           const char *passwd, const char *method,
                           const char *path, bool *finished, uerr_t *auth_err)
{
  /* We are called only with known schemes, so we can dispatch on the
     first letter. */
  switch (c_toupper (*au))
    {
    case 'B':                   /* Basic */
      *finished = true;
      return basic_authentication_encode (user, passwd);
#ifdef ENABLE_DIGEST
    case 'D':                   /* Digest */
      *finished = true;
      return digest_authentication_encode (au, user, passwd, method, path, auth_err);
#endif
#ifdef ENABLE_NTLM
    case 'N':                   /* NTLM */
      if (!ntlm_input (&pconn.ntlm, au))
        {
          *finished = true;
          return NULL;
        }
      return ntlm_output (&pconn.ntlm, user, passwd, finished);
#endif
    default:
      /* We shouldn't get here -- this function should be only called
         with values approved by known_authentication_scheme_p.  */
      abort ();
    }
}

static void
load_cookies (void)
{
  if (!wget_cookie_jar)
    wget_cookie_jar = cookie_jar_new ();
  if (opt.cookies_input && !cookies_loaded_p)
    {
      cookie_jar_load (wget_cookie_jar, opt.cookies_input);
      cookies_loaded_p = true;
    }
}

void
save_cookies (void)
{
  if (wget_cookie_jar)
    cookie_jar_save (wget_cookie_jar, opt.cookies_output);
}

#if defined DEBUG_MALLOC || defined TESTING
void
http_cleanup (void)
{
  if (pconn_active)
    invalidate_persistent ();

  if (wget_cookie_jar)
    {
      cookie_jar_delete (wget_cookie_jar);
      wget_cookie_jar = NULL;
    }

  if (basic_authed_hosts)
    {
      hash_table_iterator iter;
      for (hash_table_iterate (basic_authed_hosts, &iter); hash_table_iter_next (&iter); )
        {
          xfree (iter.key);
        }
      hash_table_destroy (basic_authed_hosts);
      basic_authed_hosts = NULL;
    }
}
#endif

void
ensure_extension (struct http_stat *hs, const char *ext, int *dt)
{
  char *last_period_in_local_filename = strrchr (hs->local_file, '.');
  char shortext[8];
  int len;
  shortext[0] = '\0';
  len = strlen (ext);
  if (len == 5)
    {
      memcpy (shortext, ext, len - 1);
      shortext[len - 1] = '\0';
    }

  if (last_period_in_local_filename == NULL
      || !(0 == strcasecmp (last_period_in_local_filename, shortext)
           || 0 == strcasecmp (last_period_in_local_filename, ext)))
    {
      int local_filename_len = strlen (hs->local_file);
      /* Resize the local file, allowing for ".html" preceded by
         optional ".NUMBER".  */
      hs->local_file = xrealloc (hs->local_file,
                                 local_filename_len + 24 + len);
      strcpy (hs->local_file + local_filename_len, ext);
      /* If clobbering is not allowed and the file, as named,
         exists, tack on ".NUMBER.html" instead. */
      if (!ALLOW_CLOBBER && file_exists_p (hs->local_file, NULL))
        {
          int ext_num = 1;
          do
            sprintf (hs->local_file + local_filename_len,
                     ".%d%s", ext_num++, ext);
          while (file_exists_p (hs->local_file, NULL));
        }
      *dt |= ADDED_HTML_EXTENSION;
    }
}

#ifdef TESTING

const char *
test_parse_range_header (void)
{
  unsigned i;
  static const struct {
    const char * rangehdr;
    const wgint firstbyte;
    const wgint lastbyte;
    const wgint length;
    const bool shouldPass;
  } test_array[] = {
      { "bytes 0-1000/1000", 0, 1000, 1000, false },
      { "bytes 0-999/1000", 0, 999, 1000, true },
      { "bytes 100-99/1000", 100, 99, 1000, false },
      { "bytes 100-100/1000", 100, 100, 1000, true },
      { "bytes 0-1000/100000000", 0, 1000, 100000000, true },
      { "bytes 1-999/1000", 1, 999, 1000, true },
      { "bytes 42-1233/1234", 42, 1233, 1234, true },
      { "bytes 42-1233/*", 42, 1233, -1, true },
      { "bytes 0-2147483648/2147483649", 0, 2147483648U, 2147483649U, true },
      { "bytes 2147483648-4294967296/4294967297", 2147483648U, 4294967296ULL, 4294967297ULL, true },
  };

  wgint firstbyteptr[sizeof(wgint)];
  wgint lastbyteptr[sizeof(wgint)];
  wgint lengthptr[sizeof(wgint)];
  bool result;
  for (i = 0; i < countof (test_array); i++)
    {
      result = parse_content_range (test_array[i].rangehdr, firstbyteptr, lastbyteptr, lengthptr);
#if 0
      printf ("%ld %ld\n", test_array[i].firstbyte, *firstbyteptr);
      printf ("%ld %ld\n", test_array[i].lastbyte, *lastbyteptr);
      printf ("%ld %ld\n", test_array[i].length, *lengthptr);
      printf ("\n");
#endif
      mu_assert ("test_parse_range_header: False Negative", result == test_array[i].shouldPass);
      mu_assert ("test_parse_range_header: Bad parse", test_array[i].firstbyte == *firstbyteptr &&
                                                       test_array[i].lastbyte == *lastbyteptr &&
                                                       test_array[i].length == *lengthptr);
    }

  return NULL;
}

const char *
test_parse_content_disposition (void)
{
  unsigned i;
  static const struct {
    const char *hdrval;
    const char *filename;
    bool result;
  } test_array[] = {
    { "filename=\"file.ext\"", "file.ext", true },
    { "attachment; filename=\"file.ext\"", "file.ext", true },
    { "attachment; filename=\"file.ext\"; dummy", "file.ext", true },
    { "attachment", NULL, false },
    { "attachment; filename*=UTF-8'en-US'hello.txt", "hello.txt", true },
    { "attachment; filename*0=\"hello\"; filename*1=\"world.txt\"",
      "helloworld.txt", true },
    { "attachment; filename=\"A.ext\"; filename*=\"B.ext\"", "B.ext", true },
    { "attachment; filename*=\"A.ext\"; filename*0=\"B\"; filename*1=\"B.ext\"",
      "A.ext", true },
    { "filename**0=\"A\"; filename**1=\"A.ext\"; filename*0=\"B\";\
filename*1=\"B\"", "AA.ext", true },
  };

  for (i = 0; i < countof (test_array); ++i)
    {
      char *filename;
      bool res;

      res = parse_content_disposition (test_array[i].hdrval, &filename);

      mu_assert ("test_parse_content_disposition: wrong result",
                 res == test_array[i].result
                 && (res == false
                     || 0 == strcmp (test_array[i].filename, filename)));
      xfree (filename);
    }

  return NULL;
}

#endif /* TESTING */

/*
 * vim: et sts=2 sw=2 cino+={s
 */
