http.c

/***************************************************************************
 *                                  _   _ ____  _     
 *  Project                     ___| | | |  _ \| |    
 *                             / __| | | | |_) | |    
 *                            | (__| |_| |  _ <| |___ 
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2004, 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>
#include <sys/types.h>
#include <sys/stat.h>

#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

#ifdef HAVE_SYS_SELECT_H
#include <sys/select.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 "http.h"

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

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

static CURLcode Curl_output_basic_proxy(struct connectdata *conn);

/*
 * 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 for HTTP Basic
 * authentication. It uses the conn->user, conn->passwd fields for it.
 *
 * Returns CURLcode.
 */
static CURLcode Curl_output_basic(struct connectdata *conn)
{
  char *authorization;
  struct SessionHandle *data=conn->data;

  sprintf(data->state.buffer, "%s:%s", conn->user, conn->passwd);
  if(Curl_base64_encode(data->state.buffer, strlen(data->state.buffer),
                        &authorization) > 0) {
    if(conn->allocptr.userpwd)
      free(conn->allocptr.userpwd);
    conn->allocptr.userpwd = aprintf( "Authorization: Basic %s\015\012",
                                      authorization);
    free(authorization);
  }
  else
    return CURLE_OUT_OF_MEMORY;
  return CURLE_OK;
}

/*
 * Curl_output_basic_proxy() sets up a proxy-Authorization: header for HTTP
 * Basic proxy authentication. It uses the conn->proxyuser and
 * conn->proxypasswd fields for it.
 *
 * Returns CURLcode.
 */
static CURLcode Curl_output_basic_proxy(struct connectdata *conn)
{
  char *authorization;
  struct SessionHandle *data=conn->data;

  sprintf(data->state.buffer, "%s:%s",
          conn->proxyuser, conn->proxypasswd);
  if(Curl_base64_encode(data->state.buffer, strlen(data->state.buffer),
                        &authorization) > 0) {
    Curl_safefree(conn->allocptr.proxyuserpwd);
    conn->allocptr.proxyuserpwd =
      aprintf("Proxy-authorization: Basic %s\015\012", authorization);
    free(authorization);
  }
  else
    return CURLE_OUT_OF_MEMORY;
  return CURLE_OK;
}

/*
 * Curl_http_auth_act() 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.
 */

void Curl_http_auth_act(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;

  if(data->state.authavail) {
    /* 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(data->state.authavail & CURLAUTH_GSSNEGOTIATE)
      data->state.authwant = CURLAUTH_GSSNEGOTIATE;
    else if(data->state.authavail & CURLAUTH_DIGEST)
      data->state.authwant = CURLAUTH_DIGEST;
    else if(data->state.authavail & CURLAUTH_NTLM)
      data->state.authwant = CURLAUTH_NTLM;
    else if(data->state.authavail & CURLAUTH_BASIC)
      data->state.authwant = CURLAUTH_BASIC;
    else
      data->state.authwant = CURLAUTH_NONE; /* clear it */

    if(data->state.authwant)
      conn->newurl = strdup(data->change.url); /* clone URL */
    data->state.authavail = CURLAUTH_NONE; /* clear it here */
  }
  else if(!data->state.authdone && (data->info.httpcode < 400)) {
    /* 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.authdone = TRUE;
    }
  }
}

/**
 * http_auth_headers() 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
 *
 * Returns CURLcode
 */
static CURLcode http_auth_headers(struct connectdata *conn,
                                  char *request,
                                  char *path)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  char *auth=NULL;

  curlassert(data);

  if(!data->state.authstage) {
    if(conn->bits.httpproxy && conn->bits.proxy_user_passwd) {
      data->state.authdone = FALSE;
      Curl_http_auth_stage(data, 407);
    }
    else if(conn->bits.user_passwd) {
      data->state.authdone = FALSE;
      Curl_http_auth_stage(data, 401);
    }
    else {
      data->state.authdone = TRUE;
      return CURLE_OK; /* no authentication with no user or password */
    }
  }

  /* 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.auth_host ||
     curl_strequal(data->state.auth_host, conn->hostname) ||
     data->set.http_disable_hostname_check_before_authentication) {

  /* Send proxy authentication header if needed */
    if (data->state.authstage == 407) {
#ifdef USE_SSLEAY
      if(data->state.authwant == CURLAUTH_NTLM) {
        auth=(char *)"NTLM";
        result = Curl_output_ntlm(conn, TRUE);
        if(result)
          return result;
      }
      else
#endif
      if(data->state.authwant == CURLAUTH_BASIC) {
        /* Basic */
        if(conn->bits.proxy_user_passwd &&
           !checkheaders(data, "Proxy-authorization:")) {
          auth=(char *)"Basic";
          result = Curl_output_basic_proxy(conn);
          if(result)
            return result;
        }
        data->state.authdone = TRUE;
        /* Switch to web authentication after proxy authentication is done */
        Curl_http_auth_stage(data, 401);
      }
      infof(data, "Proxy auth using %s with user '%s'\n",
            auth, conn->proxyuser?conn->proxyuser:"");
    }
    /* Send web authentication header if needed */
    if (data->state.authstage == 401) {
      auth = NULL;
#ifdef HAVE_GSSAPI
      if((data->state.authwant == 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;
        data->state.authdone = TRUE;
      }
      else
#endif
#ifdef USE_SSLEAY
      if(data->state.authwant == CURLAUTH_NTLM) {
        auth=(char *)"NTLM";
        result = Curl_output_ntlm(conn, FALSE);
        if(result)
          return result;
      }
      else
#endif
      {
        if((data->state.authwant == CURLAUTH_DIGEST) &&
           data->state.digest.nonce) {
          auth=(char *)"Digest";
          result = Curl_output_digest(conn,
                                      (unsigned char *)request,
                                      (unsigned char *)path);
          if(result)
            return result;
          data->state.authdone = TRUE;
        }
        else if(data->state.authwant == CURLAUTH_BASIC) {/* Basic */
          if(conn->bits.user_passwd &&
             !checkheaders(data, "Authorization:")) {
            auth=(char *)"Basic";
            result = Curl_output_basic(conn);
            if(result)
              return result;
          }
          /* basic is always ready */
          data->state.authdone = TRUE;
        }
      }
      if(auth)
        infof(data, "Server auth using %s with user '%s'\n",
              auth, conn->user);
    }
  }
  else
    data->state.authdone = TRUE;

  return result;
}


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

  long *availp;
  char *start;

  if (httpcode == 407) {
    start = header+strlen("Proxy-authenticate:");
    availp = &data->info.proxyauthavail;
  }
  else {
    start = header+strlen("WWW-Authenticate:");
    availp = &data->info.httpauthavail;
  }
  /*
   * Switch from proxy to web authentication and back if needed
   */
  if (httpcode == 407 && data->state.authstage != 407)
    Curl_http_auth_stage(data, 407);
              
  else if (httpcode == 401 && data->state.authstage != 401)
    Curl_http_auth_stage(data, 401);

  /* 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;
    if(data->state.authwant == 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
      if(data->state.authwant & CURLAUTH_GSSNEGOTIATE)
        data->state.authavail |= CURLAUTH_GSSNEGOTIATE;
  }
  else
#endif
#ifdef USE_SSLEAY
    /* NTLM support requires the SSL crypto libs */
    if(checkprefix("NTLM", start)) {
      *availp |= CURLAUTH_NTLM;
      if(data->state.authwant == CURLAUTH_NTLM) {
        /* NTLM authentication is activated */
        CURLntlm ntlm =
          Curl_input_ntlm(conn, (bool)(httpcode == 407), start);
                  
        if(CURLNTLM_BAD != ntlm) {
          conn->newurl = strdup(data->change.url); /* clone string */
          data->state.authproblem = (conn->newurl == NULL);
        }
        else {
          infof(data, "Authentication problem. Ignoring this.\n");
          data->state.authproblem = TRUE;
        }
      }
      else
        if(data->state.authwant & CURLAUTH_NTLM)
          data->state.authavail |= CURLAUTH_NTLM;
    }
    else
#endif
      if(checkprefix("Digest", start)) {
        *availp |= CURLAUTH_DIGEST;
        if(data->state.authwant == CURLAUTH_DIGEST) {
          /* Digest authentication is activated */
          CURLdigest dig = Curl_input_digest(conn, start);
          
          if(CURLDIGEST_FINE == dig) {
            /* We act on it. Store our new url, which happens to be
               the same one we already use! */
            conn->newurl = strdup(data->change.url); /* clone string */
            data->state.authproblem = (conn->newurl == NULL);
          }
          else {
            infof(data, "Authentication problem. Ignoring this.\n");
            data->state.authproblem = TRUE;
          }
        }
        else
          if(data->state.authwant & CURLAUTH_DIGEST) {
            /* We don't know if Digest is what we're gonna use, but we
               call this function anyway to store the digest data that
               is provided on this line, to skip the extra round-trip
               we need to do otherwise. We must sure to free this
               data! */
            Curl_input_digest(conn, start);
            data->state.authavail |= CURLAUTH_DIGEST;
          }
      }
      else if(checkprefix("Basic", start)) {
        *availp |= CURLAUTH_BASIC;
        if((data->state.authwant == CURLAUTH_BASIC) &&
           (httpcode == data->state.authstage)) {
          /* We asked for Basic authentication but got a 40X back
             anyway, which basicly means our name+password isn't
             valid. */
          data->state.authavail = CURLAUTH_NONE;
          infof(data, "Authentication problem. Ignoring this.\n");
          data->state.authproblem = TRUE;
        }
        else if(data->state.authwant & CURLAUTH_BASIC) {
          data->state.authavail |= CURLAUTH_BASIC;
        } else {
            /*
            ** We asked for something besides basic but got
            ** Basic anyway.  This is no good.
            */
            infof(data, "Server expects Basic auth, but we're doing something else.\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;

  /*
  ** 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

  if (data->state.authstage &&
      (data->state.authstage == k->httpcode))
    return (data->state.authdone || data->state.authproblem);

  /*
  ** Either we're not authenticating, or we're supposed to
  ** be authenticating something else.  This is an error.
  */
  return 1;
}

/*
 * 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);

    *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 = 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];

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

  /* find the end of the header line */
  end = strchr(start, '\r'); /* lines end with CRLF */
  if(!end) {
    /* in case there's a non-standard compliant line here */
    end = strchr(start, '\n');

    if(!end)
      /* hm, there's no line ending here, use the zero byte! */
      end = strchr(start, '\0');
  }

  len = end-start; /* length of the content part of the input line */
  clen = strlen(content); /* length of the word to find */

  /* find the content string in the rest of the line */
  for(;len>=clen;len--, start++) {
    if(strnequal(start, content, clen))
      return TRUE; /* match! */
  }

  return FALSE; /* no match */
}

/*
 * ConnectHTTPProxyTunnel() requires that we're connected to a HTTP proxy. This
 * function will issue the necessary commands to get a seamless tunnel through
 * this proxy. After that, the socket can be used just as a normal socket.
 */

CURLcode Curl_ConnectHTTPProxyTunnel(struct connectdata *conn,
                                     int sockindex,
                                     char *hostname,
                                     int remote_port)
{
  int httpcode=0;
  int subversion=0;
  struct SessionHandle *data=conn->data;
  CURLcode result;
  int res;

  size_t nread;   /* total size read */
  int perline; /* count bytes per line */
  bool keepon=TRUE;
  ssize_t gotbytes;
  char *ptr;
  long timeout = 3600; /* default timeout in seconds */
  struct timeval interval;
  fd_set rkeepfd;
  fd_set readfd;
  char *line_start;
  char *host_port;
  curl_socket_t tunnelsocket = conn->sock[sockindex];

#define SELECT_OK      0
#define SELECT_ERROR   1
#define SELECT_TIMEOUT 2
  int error = SELECT_OK;

  infof(data, "Establish HTTP proxy tunnel to %s:%d\n", hostname, remote_port);

  do {
    if(conn->newurl) {
      /* This only happens if we've looped here due to authentication reasons,
         and we don't really use the newly cloned URL here then. Just free()
         it. */
      free(conn->newurl); 
      conn->newurl = NULL;
    }

    host_port = aprintf("%s:%d", hostname, remote_port);
    if(!host_port)
      return CURLE_OUT_OF_MEMORY;

    /* Setup the proxy-authorization header, if any */
    result = http_auth_headers(conn, (char *)"CONNECT", host_port);
    if(CURLE_OK == result) {

      /* OK, now send the connect request to the proxy */
      result =
        Curl_sendf(tunnelsocket, conn,
                   "CONNECT %s:%d HTTP/1.0\015\012"
                   "%s"
                   "%s"
                   "\r\n",
                   hostname, remote_port,
                   conn->bits.proxy_user_passwd?
                   conn->allocptr.proxyuserpwd:"",
                   data->set.useragent?conn->allocptr.uagent:""
                   );
      if(result)
        failf(data, "Failed sending CONNECT to proxy");
    }
    free(host_port);
    if(result)
      return result;

    FD_ZERO (&readfd);		/* clear it */
    FD_SET (tunnelsocket, &readfd);     /* read socket */

    /* get this in a backup variable to be able to restore it on each lap in
       the select() loop */
    rkeepfd = readfd;

    ptr=data->state.buffer;
    line_start = ptr;

    nread=0;
    perline=0;
    keepon=TRUE;

    while((nread<BUFSIZE) && (keepon && !error)) {
      readfd = rkeepfd;     /* set every lap */
      interval.tv_sec = 1;  /* timeout each second and check the timeout */
      interval.tv_usec = 0;

      if(data->set.timeout) {
        /* if timeout is requested, find out how much remaining time we have */
        timeout = data->set.timeout - /* timeout time */
          Curl_tvdiff(Curl_tvnow(), conn->now)/1000; /* spent time */
        if(timeout <=0 ) {
          failf(data, "Proxy connection aborted due to timeout");
          error = SELECT_TIMEOUT; /* already too little time */
          break;
        }
      }
      
      switch (select (tunnelsocket+1, &readfd, NULL, NULL, &interval)) {
      case -1: /* select() error, stop reading */
        error = SELECT_ERROR;
        failf(data, "Proxy CONNECT aborted due to select() error");
        break;
      case 0: /* timeout */
        break;
      default:
        /*
         * This code previously didn't use the kerberos sec_read() code
         * to read, but when we use Curl_read() it may do so. Do confirm
         * that this is still ok and then remove this comment!
         */
        res= Curl_read(conn, tunnelsocket, ptr, BUFSIZE-nread, &gotbytes);
        if(res< 0)
          /* EWOULDBLOCK */
          continue; /* go loop yourself */
        else if(res)
          keepon = FALSE;
        else if(gotbytes <= 0) {
          keepon = FALSE;
          error = SELECT_ERROR;
          failf(data, "Proxy CONNECT aborted");
        }
        else {
          /*
           * We got a whole chunk of data, which can be anything from one byte
           * to a set of lines and possibly just a piece of the last line.
           *
           * TODO: To make this code work less error-prone, we need to make
           * sure that we read and create full lines before we compare them,