http.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2005, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 ***************************************************************************/

#include "setup.h"

#ifndef CURL_DISABLE_HTTP
/* -- WIN32 approved -- */
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <ctype.h>
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

#include <errno.h>

#if defined(WIN32) && !defined(__GNUC__) || defined(__MINGW32__)
#include <time.h>
#include <io.h>
#else
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <sys/time.h>

#ifdef HAVE_TIME_H
#ifdef TIME_WITH_SYS_TIME
#include <time.h>
#endif
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <netdb.h>
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_NET_IF_H
#include <net/if.h>
#endif
#include <sys/ioctl.h>
#include <signal.h>

#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

#endif

#include "urldata.h"
#include <curl/curl.h>
#include "transfer.h"
#include "sendf.h"
#include "formdata.h"
#include "progress.h"
#include "base64.h"
#include "cookie.h"
#include "strequal.h"
#include "ssluse.h"
#include "http_digest.h"
#include "http_ntlm.h"
#include "http_negotiate.h"
#include "url.h"
#include "share.h"
#include "hostip.h"
#include "http.h"
#include "memory.h"
#include "select.h"
#include "parsedate.h" /* for the week day and month names */

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

/* The last #include file should be: */
#include "memdebug.h"

/*
 * checkheaders() checks the linked list of custom HTTP headers for a
 * particular header (prefix).
 *
 * Returns a pointer to the first matching header or NULL if none matched.
 */
static char *checkheaders(struct SessionHandle *data, const char *thisheader)
{
  struct curl_slist *head;
  size_t thislen = strlen(thisheader);

  for(head = data->set.headers; head; head=head->next) {
    if(strnequal(head->data, thisheader, thislen))
      return head->data;
  }
  return NULL;
}

/*
 * Curl_output_basic() sets up an Authorization: header (or the proxy version)
 * for HTTP Basic authentication.
 *
 * Returns CURLcode.
 */
static CURLcode Curl_output_basic(struct connectdata *conn, bool proxy)
{
  char *authorization;
  struct SessionHandle *data=conn->data;
  char **userp;
  char *user;
  char *pwd;

  if(proxy) {
    userp = &conn->allocptr.proxyuserpwd;
    user = conn->proxyuser;
    pwd = conn->proxypasswd;
  }
  else {
    userp = &conn->allocptr.userpwd;
    user = conn->user;
    pwd = conn->passwd;
  }

  snprintf(data->state.buffer, sizeof(data->state.buffer), "%s:%s", user, pwd);
  if(Curl_base64_encode(data->state.buffer,
                        strlen(data->state.buffer),
                        &authorization) > 0) {
    if(*userp)
      free(*userp);
    *userp = aprintf( "%sAuthorization: Basic %s\015\012",
                      proxy?"Proxy-":"",
                      authorization);
    free(authorization);
  }
  else
    return CURLE_OUT_OF_MEMORY;
  return CURLE_OK;
}

/* pickoneauth() selects the most favourable authentication method from the
 * ones available and the ones we want.
 *
 * return TRUE if one was picked
 */
static bool pickoneauth(struct auth *pick)
{
  bool picked;
  /* only deal with authentication we want */
  long avail = pick->avail & pick->want;
  picked = TRUE;

  /* The order of these checks is highly relevant, as this will be the order
     of preference in case of the existance of multiple accepted types. */
  if(avail & CURLAUTH_GSSNEGOTIATE)
    pick->picked = CURLAUTH_GSSNEGOTIATE;
  else if(avail & CURLAUTH_DIGEST)
    pick->picked = CURLAUTH_DIGEST;
  else if(avail & CURLAUTH_NTLM)
    pick->picked = CURLAUTH_NTLM;
  else if(avail & CURLAUTH_BASIC)
    pick->picked = CURLAUTH_BASIC;
  else {
    pick->picked = CURLAUTH_PICKNONE; /* we select to use nothing */
    picked = FALSE;
  }
  pick->avail = CURLAUTH_NONE; /* clear it here */

  return picked;
}

/*
 * perhapsrewind()
 *
 * If we are doing POST or PUT {
 *   If we have more data to send {
 *     If we are doing NTLM {
 *       Keep sending since we must not disconnect
 *     }
 *     else {
 *       If there is more than just a little data left to send, close
 *       the current connection by force.
 *     }
 *   }
 *   If we have sent any data {
 *     If we don't have track of all the data {
 *       call app to tell it to rewind
 *     }
 *     else {
 *       rewind internally so that the operation can restart fine
 *     }
 *   }
 * }
 */
static CURLcode perhapsrewind(struct connectdata *conn)
{
  struct HTTP *http = conn->proto.http;
  struct SessionHandle *data = conn->data;
  curl_off_t bytessent;
  curl_off_t expectsend = -1; /* default is unknown */

  if(!http)
    /* If this is still NULL, we have not reach very far and we can
       safely skip this rewinding stuff */
    return CURLE_OK;

  bytessent = http->writebytecount;

  /* figure out how much data we are expected to send */
  switch(data->set.httpreq) {
  case HTTPREQ_POST:
    if(data->set.postfieldsize != -1)
      expectsend = data->set.postfieldsize;
    break;
  case HTTPREQ_PUT:
    if(data->set.infilesize != -1)
      expectsend = data->set.infilesize;
    break;
  case HTTPREQ_POST_FORM:
    expectsend = http->postsize;
    break;
  default:
    break;
  }

  conn->bits.rewindaftersend = FALSE; /* default */

  if((expectsend == -1) || (expectsend > bytessent)) {
    /* There is still data left to send */
    if((data->state.authproxy.picked == CURLAUTH_NTLM) ||
       (data->state.authhost.picked == CURLAUTH_NTLM)) {
      if(((expectsend - bytessent) < 2000) ||
         (conn->ntlm.state != NTLMSTATE_NONE)) {
        /* The NTLM-negotiation has started *OR* there is just a little (<2K)
           data left to send, keep on sending. */

        /* rewind data when completely done sending! */
        if(!conn->bits.authneg)
          conn->bits.rewindaftersend = TRUE;

        return CURLE_OK;
      }
      if(conn->bits.close)
        /* this is already marked to get closed */
        return CURLE_OK;

      infof(data, "NTLM send, close instead of sending %ld bytes\n",
            expectsend - bytessent);
    }

    /* This is not NTLM or NTLM with many bytes left to send: close
     */
    conn->bits.close = TRUE;
    conn->size = 0; /* don't download any more than 0 bytes */
  }

  if(bytessent)
    return Curl_readrewind(conn);

  return CURLE_OK;
}

/*
 * Curl_http_auth_act() gets called when a all HTTP headers have been received
 * and it checks what authentication methods that are available and decides
 * which one (if any) to use. It will set 'newurl' if an auth metod was
 * picked.
 */

CURLcode Curl_http_auth_act(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  bool pickhost = FALSE;
  bool pickproxy = FALSE;
  CURLcode code = CURLE_OK;

  if(data->state.authproblem)
    return data->set.http_fail_on_error?CURLE_HTTP_RETURNED_ERROR:CURLE_OK;

  if(conn->bits.user_passwd &&
     ((conn->keep.httpcode == 401) ||
      (conn->bits.authneg && conn->keep.httpcode < 300))) {
    pickhost = pickoneauth(&data->state.authhost);
    if(!pickhost)
      data->state.authproblem = TRUE;
  }
  if(conn->bits.proxy_user_passwd &&
     ((conn->keep.httpcode == 407) ||
      (conn->bits.authneg && conn->keep.httpcode < 300))) {
    pickproxy = pickoneauth(&data->state.authproxy);
    if(!pickproxy)
      data->state.authproblem = TRUE;
  }

  if(pickhost || pickproxy) {
    conn->newurl = strdup(data->change.url); /* clone URL */

    if((data->set.httpreq != HTTPREQ_GET) &&
       (data->set.httpreq != HTTPREQ_HEAD) &&
       !conn->bits.rewindaftersend) {
      code = perhapsrewind(conn);
      if(code)
        return code;
    }
  }

  else if((conn->keep.httpcode < 300) &&
          (!data->state.authhost.done) &&
          conn->bits.authneg) {
    /* no (known) authentication available,
       authentication is not "done" yet and
       no authentication seems to be required and
       we didn't try HEAD or GET */
    if((data->set.httpreq != HTTPREQ_GET) &&
       (data->set.httpreq != HTTPREQ_HEAD)) {
      conn->newurl = strdup(data->change.url); /* clone URL */
      data->state.authhost.done = TRUE;
    }
  }
  if (Curl_http_should_fail(conn)) {
    failf (data, "The requested URL returned error: %d",
           conn->keep.httpcode);
    code = CURLE_HTTP_RETURNED_ERROR;
  }

  return code;
}

/**
 * Curl_http_output_auth() setups the authentication headers for the
 * host/proxy and the correct authentication
 * method. conn->data->state.authdone is set to TRUE when authentication is
 * done.
 *
 * @param conn all information about the current connection
 * @param request pointer to the request keyword
 * @param path pointer to the requested path
 * @param proxytunnel boolean if this is the request setting up a "proxy
 * tunnel"
 *
 * @returns CURLcode
 */
static CURLcode
Curl_http_output_auth(struct connectdata *conn,
                      char *request,
                      char *path,
                      bool proxytunnel) /* TRUE if this is the request setting
                                           up the proxy tunnel */
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  char *auth=NULL;
  struct auth *authhost;
  struct auth *authproxy;

  curlassert(data);

  authhost = &data->state.authhost;
  authproxy = &data->state.authproxy;

  if((conn->bits.httpproxy && conn->bits.proxy_user_passwd) ||
     conn->bits.user_passwd)
    /* continue please */ ;
  else {
    authhost->done = TRUE;
    authproxy->done = TRUE;
    return CURLE_OK; /* no authentication with no user or password */
  }

  if(authhost->want && !authhost->picked)
    /* The app has selected one or more methods, but none has been picked
       so far by a server round-trip. Then we set the picked one to the
       want one, and if this is one single bit it'll be used instantly. */
    authhost->picked = authhost->want;

  if(authproxy->want && !authproxy->picked)
    /* The app has selected one or more methods, but none has been picked so
       far by a proxy round-trip. Then we set the picked one to the want one,
       and if this is one single bit it'll be used instantly. */
    authproxy->picked = authproxy->want;

  /* Send proxy authentication header if needed */
  if (conn->bits.httpproxy &&
      (conn->bits.tunnel_proxy == proxytunnel)) {
#if defined(USE_SSLEAY) || defined(USE_WINDOWS_SSPI)
    if(authproxy->picked == CURLAUTH_NTLM) {
      auth=(char *)"NTLM";
      result = Curl_output_ntlm(conn, TRUE);
      if(result)
        return result;
    }
    else
#endif
      if(authproxy->picked == CURLAUTH_BASIC) {
        /* Basic */
        if(conn->bits.proxy_user_passwd &&
           !checkheaders(data, "Proxy-authorization:")) {
          auth=(char *)"Basic";
          result = Curl_output_basic(conn, TRUE);
          if(result)
            return result;
        }
        /* NOTE: Curl_output_basic() should set 'done' TRUE, as the other auth
           functions work that way */
        authproxy->done = TRUE;
      }
#ifndef CURL_DISABLE_CRYPTO_AUTH
      else if(authproxy->picked == CURLAUTH_DIGEST) {
        auth=(char *)"Digest";
        result = Curl_output_digest(conn,
                                    TRUE, /* proxy */
                                    (unsigned char *)request,
                                    (unsigned char *)path);
        if(result)
          return result;
      }
#endif
      if(auth) {
        infof(data, "Proxy auth using %s with user '%s'\n",
              auth, conn->proxyuser?conn->proxyuser:"");
        authproxy->multi = !authproxy->done;
      }
      else
        authproxy->multi = FALSE;
    }
  else
    /* we have no proxy so let's pretend we're done authenticating
       with it */
    authproxy->done = TRUE;

  /* To prevent the user+password to get sent to other than the original
     host due to a location-follow, we do some weirdo checks here */
  if(!data->state.this_is_a_follow ||
     !data->state.first_host ||
     curl_strequal(data->state.first_host, conn->host.name) ||
     data->set.http_disable_hostname_check_before_authentication) {

    /* Send web authentication header if needed */
    {
      auth = NULL;
#ifdef HAVE_GSSAPI
      if((authhost->picked == CURLAUTH_GSSNEGOTIATE) &&
         data->state.negotiate.context &&
         !GSS_ERROR(data->state.negotiate.status)) {
        auth=(char *)"GSS-Negotiate";
        result = Curl_output_negotiate(conn);
        if (result)
          return result;
        authhost->done = TRUE;
      }
      else
#endif
#if defined(USE_SSLEAY) || defined(USE_WINDOWS_SSPI)
      if(authhost->picked == CURLAUTH_NTLM) {
        auth=(char *)"NTLM";
        result = Curl_output_ntlm(conn, FALSE);
        if(result)
          return result;
      }
      else
#endif
      {
#ifndef CURL_DISABLE_CRYPTO_AUTH
        if(authhost->picked == CURLAUTH_DIGEST) {
          auth=(char *)"Digest";
          result = Curl_output_digest(conn,
                                      FALSE, /* not a proxy */
                                      (unsigned char *)request,
                                      (unsigned char *)path);
          if(result)
            return result;
        } else
#endif
        if(authhost->picked == CURLAUTH_BASIC) {
          if(conn->bits.user_passwd &&
             !checkheaders(data, "Authorization:")) {
            auth=(char *)"Basic";
            result = Curl_output_basic(conn, FALSE);
            if(result)
              return result;
          }
          /* basic is always ready */
          authhost->done = TRUE;
        }
      }
      if(auth) {
        infof(data, "Server auth using %s with user '%s'\n",
              auth, conn->user);

        authhost->multi = !authhost->done;
      }
      else
        authhost->multi = FALSE;
    }
  }
  else
    authhost->done = TRUE;

  return result;
}


/*
 * Curl_http_input_auth() deals with Proxy-Authenticate: and WWW-Authenticate:
 * headers. They are dealt with both in the transfer.c main loop and in the
 * proxy CONNECT loop.
 */

CURLcode Curl_http_input_auth(struct connectdata *conn,
                              int httpcode,
                              char *header) /* the first non-space */
{
  /*
   * This resource requires authentication
   */
  struct SessionHandle *data = conn->data;

  long *availp;
  char *start;
  struct auth *authp;

  if (httpcode == 407) {
    start = header+strlen("Proxy-authenticate:");
    availp = &data->info.proxyauthavail;
    authp = &data->state.authproxy;
  }
  else {
    start = header+strlen("WWW-Authenticate:");
    availp = &data->info.httpauthavail;
    authp = &data->state.authhost;
  }

  /* pass all white spaces */
  while(*start && isspace((int)*start))
    start++;

  /*
   * Here we check if we want the specific single authentiction (using ==) and
   * if we do, we initiate usage of it.
   *
   * If the provided authentication is wanted as one out of several accepted
   * types (using &), we OR this authenticaion type to the authavail
   * variable.
   */

#ifdef HAVE_GSSAPI
  if (checkprefix("GSS-Negotiate", start) ||
      checkprefix("Negotiate", start)) {
    *availp |= CURLAUTH_GSSNEGOTIATE;
    authp->avail |= CURLAUTH_GSSNEGOTIATE;
    if(authp->picked == CURLAUTH_GSSNEGOTIATE) {
      /* if exactly this is wanted, go */
      int neg = Curl_input_negotiate(conn, start);
      if (neg == 0) {
        conn->newurl = strdup(data->change.url);
        data->state.authproblem = (conn->newurl == NULL);
      }
      else {
        infof(data, "Authentication problem. Ignoring this.\n");
        data->state.authproblem = TRUE;
      }
    }
  }
  else
#endif
#if defined(USE_SSLEAY) || defined(USE_WINDOWS_SSPI)
    /* NTLM support requires the SSL crypto libs */
    if(checkprefix("NTLM", start)) {
      *availp |= CURLAUTH_NTLM;
      authp->avail |= CURLAUTH_NTLM;
      if(authp->picked == CURLAUTH_NTLM) {
        /* NTLM authentication is picked and activated */
        CURLntlm ntlm =
          Curl_input_ntlm(conn, (bool)(httpcode == 407), start);

        if(CURLNTLM_BAD != ntlm)
          data->state.authproblem = FALSE;
        else {
          infof(data, "Authentication problem. Ignoring this.\n");
          data->state.authproblem = TRUE;
        }
      }
    }
    else
#endif
#ifndef CURL_DISABLE_CRYPTO_AUTH
      if(checkprefix("Digest", start)) {
        CURLdigest dig;
        *availp |= CURLAUTH_DIGEST;
        authp->avail |= CURLAUTH_DIGEST;

        /* We call this function on input Digest headers even if Digest
         * authentication isn't activated yet, as we need to store the
         * incoming data from this header in case we are gonna use Digest. */
        dig = Curl_input_digest(conn, (bool)(httpcode == 407), start);

        if(CURLDIGEST_FINE != dig) {
          infof(data, "Authentication problem. Ignoring this.\n");
          data->state.authproblem = TRUE;
        }
      }
      else
#endif
      if(checkprefix("Basic", start)) {
        *availp |= CURLAUTH_BASIC;
        authp->avail |= CURLAUTH_BASIC;
        if(authp->picked == CURLAUTH_BASIC) {
          /* We asked for Basic authentication but got a 40X back
             anyway, which basicly means our name+password isn't
             valid. */
          authp->avail = CURLAUTH_NONE;
          infof(data, "Authentication problem. Ignoring this.\n");
          data->state.authproblem = TRUE;
        }
      }

  return CURLE_OK;
}

/**
 * Curl_http_should_fail() determines whether an HTTP response has gotten us
 * into an error state or not.
 *
 * @param conn all information about the current connection
 *
 * @retval 0 communications should continue
 *
 * @retval 1 communications should not continue
 */
int Curl_http_should_fail(struct connectdata *conn)
{
  struct SessionHandle *data;
  struct Curl_transfer_keeper *k;

  curlassert(conn);
  data = conn->data;
  curlassert(data);

  /*
  ** For readability
  */
  k = &conn->keep;

  /*
  ** If we haven't been asked to fail on error,
  ** don't fail.
  */
  if (!data->set.http_fail_on_error)
    return 0;

  /*
  ** Any code < 400 is never terminal.
  */
  if (k->httpcode < 400)
    return 0;

  if (conn->resume_from &&
      (data->set.httpreq==HTTPREQ_GET) &&
      (k->httpcode == 416)) {
    /* "Requested Range Not Satisfiable", just proceed and
       pretend this is no error */
    return 0;
  }

  /*
  ** Any code >= 400 that's not 401 or 407 is always
  ** a terminal error
  */
  if ((k->httpcode != 401) &&
      (k->httpcode != 407))
    return 1;

  /*
  ** All we have left to deal with is 401 and 407
  */
  curlassert((k->httpcode == 401) || (k->httpcode == 407));

  /*
  ** Examine the current authentication state to see if this
  ** is an error.  The idea is for this function to get
  ** called after processing all the headers in a response
  ** message.  So, if we've been to asked to authenticate a
  ** particular stage, and we've done it, we're OK.  But, if
  ** we're already completely authenticated, it's not OK to
  ** get another 401 or 407.
  **
  ** It is possible for authentication to go stale such that
  ** the client needs to reauthenticate.  Once that info is
  ** available, use it here.
  */
#if 0 /* set to 1 when debugging this functionality */
  infof(data,"%s: authstage = %d\n",__FUNCTION__,data->state.authstage);
  infof(data,"%s: authwant = 0x%08x\n",__FUNCTION__,data->state.authwant);
  infof(data,"%s: authavail = 0x%08x\n",__FUNCTION__,data->state.authavail);
  infof(data,"%s: httpcode = %d\n",__FUNCTION__,k->httpcode);
  infof(data,"%s: authdone = %d\n",__FUNCTION__,data->state.authdone);
  infof(data,"%s: newurl = %s\n",__FUNCTION__,conn->newurl ? conn->newurl : "(null)");
  infof(data,"%s: authproblem = %d\n",__FUNCTION__,data->state.authproblem);
#endif

  /*
  ** Either we're not authenticating, or we're supposed to
  ** be authenticating something else.  This is an error.
  */
  if((k->httpcode == 401) && !conn->bits.user_passwd)
    return TRUE;
  if((k->httpcode == 407) && !conn->bits.proxy_user_passwd)
    return TRUE;

  return data->state.authproblem;
}

/*
 * readmoredata() is a "fread() emulation" to provide POST and/or request
 * data. It is used when a huge POST is to be made and the entire chunk wasn't
 * sent in the first send(). This function will then be called from the
 * transfer.c loop when more data is to be sent to the peer.
 *
 * Returns the amount of bytes it filled the buffer with.
 */
static size_t readmoredata(char *buffer,
                           size_t size,
                           size_t nitems,
                           void *userp)
{
  struct connectdata *conn = (struct connectdata *)userp;
  struct HTTP *http = conn->proto.http;
  size_t fullsize = size * nitems;

  if(0 == http->postsize)
    /* nothing to return */
    return 0;

  /* make sure that a HTTP request is never sent away chunked! */
  conn->bits.forbidchunk= (http->sending == HTTPSEND_REQUEST)?TRUE:FALSE;

  if(http->postsize <= (curl_off_t)fullsize) {
    memcpy(buffer, http->postdata, (size_t)http->postsize);
    fullsize = (size_t)http->postsize;

    if(http->backup.postsize) {
      /* move backup data into focus and continue on that */
      http->postdata = http->backup.postdata;
      http->postsize = http->backup.postsize;
      conn->fread =    http->backup.fread;
      conn->fread_in = http->backup.fread_in;

      http->sending++; /* move one step up */

      http->backup.postsize=0;
    }
    else
      http->postsize = 0;

    return fullsize;
  }

  memcpy(buffer, http->postdata, fullsize);
  http->postdata += fullsize;
  http->postsize -= fullsize;

  return fullsize;
}

/* ------------------------------------------------------------------------- */
/*
 * The add_buffer series of functions are used to build one large memory chunk
 * from repeated function invokes. Used so that the entire HTTP request can
 * be sent in one go.
 */

struct send_buffer {
  char *buffer;
  size_t size_max;
  size_t size_used;
};
typedef struct send_buffer send_buffer;

static CURLcode
 add_buffer(send_buffer *in, const void *inptr, size_t size);

/*
 * add_buffer_init() sets up and returns a fine buffer struct
 */
static
send_buffer *add_buffer_init(void)
{
  send_buffer *blonk;
  blonk=(send_buffer *)malloc(sizeof(send_buffer));
  if(blonk) {
    memset(blonk, 0, sizeof(send_buffer));
    return blonk;
  }
  return NULL; /* failed, go home */
}

/*
 * add_buffer_send() sends a buffer and frees all associated memory.
 *
 * Returns CURLcode
 */
static
CURLcode add_buffer_send(send_buffer *in,
                         struct connectdata *conn,
                         long *bytes_written) /* add the number of sent
                                                 bytes to this counter */
{
  ssize_t amount;
  CURLcode res;
  char *ptr;
  size_t size;
  struct HTTP *http = conn->proto.http;
  size_t sendsize;
  curl_socket_t sockfd = conn->sock[FIRSTSOCKET];

  /* The looping below is required since we use non-blocking sockets, but due
     to the circumstances we will just loop and try again and again etc */

  ptr = in->buffer;
  size = in->size_used;

  if(conn->protocol & PROT_HTTPS) {
    /* We never send more than CURL_MAX_WRITE_SIZE bytes in one single chunk
       when we speak HTTPS, as if only a fraction of it is sent now, this data
       needs to fit into the normal read-callback buffer later on and that
       buffer is using this size.
    */

    sendsize= (size > CURL_MAX_WRITE_SIZE)?CURL_MAX_WRITE_SIZE:size;

    /* OpenSSL is very picky and we must send the SAME buffer pointer to the
       library when we attempt to re-send this buffer. Sending the same data
       is not enough, we must use the exact same address. For this reason, we
       must copy the data to the uploadbuffer first, since that is the buffer
       we will be using if this send is retried later.
    */
    memcpy(conn->data->state.uploadbuffer, ptr, sendsize);
    ptr = conn->data->state.uploadbuffer;
  }
  else
    sendsize = size;

  res = Curl_write(conn, sockfd, ptr, sendsize, &amount);

  if(CURLE_OK == res) {

    if(conn->data->set.verbose)
      /* this data _may_ contain binary stuff */
      Curl_debug(conn->data, CURLINFO_HEADER_OUT, ptr, amount, conn);

    *bytes_written += amount;

    if((size_t)amount != size) {
      /* The whole request could not be sent in one system call. We must queue
         it up and send it later when we get the chance. We must not loop here
         and wait until it might work again. */

      size -= amount;

      ptr = in->buffer + amount;

      /* backup the currently set pointers */
      http->backup.fread = conn->fread;
      http->backup.fread_in = conn->fread_in;
      http->backup.postdata = http->postdata;
      http->backup.postsize = http->postsize;

      /* set the new pointers for the request-sending */
      conn->fread = (curl_read_callback)readmoredata;
      conn->fread_in = (void *)conn;
      http->postdata = ptr;
      http->postsize = (curl_off_t)size;

      http->send_buffer = in;
      http->sending = HTTPSEND_REQUEST;

      return CURLE_OK;
    }
    http->sending = HTTPSEND_BODY;
    /* the full buffer was sent, clean up and return */
  }
  if(in->buffer)
    free(in->buffer);
  free(in);

  return res;
}


/*
 * add_bufferf() add the formatted input to the buffer.
 */
static
CURLcode add_bufferf(send_buffer *in, const char *fmt, ...)
{
  char *s;
  va_list ap;
  va_start(ap, fmt);
  s = vaprintf(fmt, ap); /* this allocs a new string to append */
  va_end(ap);

  if(s) {
    CURLcode result = add_buffer(in, s, strlen(s));
    free(s);
    if(CURLE_OK == result)
      return CURLE_OK;
  }
  /* If we failed, we cleanup the whole buffer and return error */
  if(in->buffer)
    free(in->buffer);
  free(in);
  return CURLE_OUT_OF_MEMORY;
}

/*
 * add_buffer() appends a memory chunk to the existing buffer
 */
static
CURLcode add_buffer(send_buffer *in, const void *inptr, size_t size)
{
  char *new_rb;
  size_t new_size;

  if(!in->buffer ||
     ((in->size_used + size) > (in->size_max - 1))) {
    new_size = (in->size_used+size)*2;
    if(in->buffer)
      /* we have a buffer, enlarge the existing one */
      new_rb = (char *)realloc(in->buffer, new_size);
    else
      /* create a new buffer */
      new_rb = (char *)malloc(new_size);

    if(!new_rb)
      return CURLE_OUT_OF_MEMORY;

    in->buffer = new_rb;
    in->size_max = new_size;
  }
  memcpy(&in->buffer[in->size_used], inptr, size);

  in->size_used += size;

  return CURLE_OK;
}

/* end of the add_buffer functions */
/* ------------------------------------------------------------------------- */

/*
 * Curl_compareheader()
 *
 * Returns TRUE if 'headerline' contains the 'header' with given 'content'.
 * Pass headers WITH the colon.
 */
bool
Curl_compareheader(char *headerline,    /* line to check */
                   const char *header,  /* header keyword _with_ colon */
                   const char *content) /* content string to find */
{
  /* RFC2616, section 4.2 says: "Each header field consists of a name followed
   * by a colon (":") and the field value. Field names are case-insensitive.
   * The field value MAY be preceded by any amount of LWS, though a single SP
   * is preferred." */

  size_t hlen = strlen(header);
  size_t clen;
  size_t len;
  char *start;
  char *end;

  if(!strnequal(headerline, header, hlen))
    return FALSE; /* doesn't start with header */

  /* pass the header */
  start = &headerline[hlen];