transfer.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2009, 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"

/* -- WIN32 approved -- */
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>

#include "strtoofft.h"
#include "strequal.h"
#include "rawstr.h"

#ifdef WIN32
#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
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_NET_IF_H
#include <net/if.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif

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

#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif

#ifndef HAVE_SOCKET
#error "We can't compile without socket() support!"
#endif

#endif  /* WIN32 */

#include "urldata.h"
#include <curl/curl.h>
#include "netrc.h"

#include "content_encoding.h"
#include "hostip.h"
#include "transfer.h"
#include "sendf.h"
#include "speedcheck.h"
#include "progress.h"
#include "http.h"
#include "url.h"
#include "getinfo.h"
#include "sslgen.h"
#include "http_digest.h"
#include "http_ntlm.h"
#include "http_negotiate.h"
#include "share.h"
#include "curl_memory.h"
#include "select.h"
#include "multiif.h"
#include "easyif.h" /* for Curl_convert_to_network prototype */

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

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

#define CURL_TIMEOUT_EXPECT_100 1000 /* counting ms here */


#ifndef CURL_DISABLE_HTTP
static CURLcode readwrite_http_headers(struct SessionHandle *data,
                                       struct connectdata *conn,
                                       struct SingleRequest *k,
                                       ssize_t *nread,
                                       bool *stop_reading);
#endif /* CURL_DISABLE_HTTP */

/*
 * This function will call the read callback to fill our buffer with data
 * to upload.
 */
CURLcode Curl_fillreadbuffer(struct connectdata *conn, int bytes, int *nreadp)
{
  struct SessionHandle *data = conn->data;
  size_t buffersize = (size_t)bytes;
  int nread;
#ifdef CURL_DOES_CONVERSIONS
  bool sending_http_headers = FALSE;

  if((conn->protocol&PROT_HTTP) &&
     (data->state.proto.http->sending == HTTPSEND_REQUEST)) {
    /* We're sending the HTTP request headers, not the data.
       Remember that so we don't re-translate them into garbage. */
    sending_http_headers = TRUE;
  }
#endif

  if(data->req.upload_chunky) {
    /* if chunked Transfer-Encoding */
    buffersize -= (8 + 2 + 2);   /* 32bit hex + CRLF + CRLF */
    data->req.upload_fromhere += (8 + 2); /* 32bit hex + CRLF */
  }

  /* this function returns a size_t, so we typecast to int to prevent warnings
     with picky compilers */
  nread = (int)conn->fread_func(data->req.upload_fromhere, 1,
                                buffersize, conn->fread_in);

  if(nread == CURL_READFUNC_ABORT) {
    failf(data, "operation aborted by callback");
    *nreadp = 0;
    return CURLE_ABORTED_BY_CALLBACK;
  }
  else if(nread == CURL_READFUNC_PAUSE) {
    struct SingleRequest *k = &data->req;
    /* CURL_READFUNC_PAUSE pauses read callbacks that feed socket writes */
    k->keepon |= KEEP_SEND_PAUSE; /* mark socket send as paused */
    if(data->req.upload_chunky) {
      /* Back out the preallocation done above */
      data->req.upload_fromhere -= (8 + 2);
    }
    *nreadp = 0;
    return CURLE_OK; /* nothing was read */
  }
  else if((size_t)nread > buffersize) {
    /* the read function returned a too large value */
    *nreadp = 0;
    failf(data, "read function returned funny value");
    return CURLE_READ_ERROR;
  }

  if(!data->req.forbidchunk && data->req.upload_chunky) {
    /* if chunked Transfer-Encoding
     *    build chunk:
     *
     *        <HEX SIZE> CRLF
     *        <DATA> CRLF
     */
    /* On non-ASCII platforms the <DATA> may or may not be
       translated based on set.prefer_ascii while the protocol
       portion must always be translated to the network encoding.
       To further complicate matters, line end conversion might be
       done later on, so we need to prevent CRLFs from becoming
       CRCRLFs if that's the case.  To do this we use bare LFs
       here, knowing they'll become CRLFs later on.
     */

    char hexbuffer[11];
    const char *endofline_native;
    const char *endofline_network;
    int hexlen;
#ifdef CURL_DO_LINEEND_CONV
    if((data->set.crlf) || (data->set.prefer_ascii)) {
#else
    if(data->set.crlf) {
#endif /* CURL_DO_LINEEND_CONV */
      /* \n will become \r\n later on */
      endofline_native  = "\n";
      endofline_network = "\x0a";
    } else {
      endofline_native  = "\r\n";
      endofline_network = "\x0d\x0a";
    }
    hexlen = snprintf(hexbuffer, sizeof(hexbuffer),
                      "%x%s", nread, endofline_native);

    /* move buffer pointer */
    data->req.upload_fromhere -= hexlen;
    nread += hexlen;

    /* copy the prefix to the buffer, leaving out the NUL */
    memcpy(data->req.upload_fromhere, hexbuffer, hexlen);

    /* always append ASCII CRLF to the data */
    memcpy(data->req.upload_fromhere + nread,
           endofline_network,
           strlen(endofline_network));

#ifdef CURL_DOES_CONVERSIONS
    CURLcode res;
    int length;
    if(data->set.prefer_ascii) {
      /* translate the protocol and data */
      length = nread;
    } else {
      /* just translate the protocol portion */
      length = strlen(hexbuffer);
    }
    res = Curl_convert_to_network(data, data->req.upload_fromhere, length);
    /* Curl_convert_to_network calls failf if unsuccessful */
    if(res != CURLE_OK) {
      return(res);
    }
#endif /* CURL_DOES_CONVERSIONS */

    if((nread - hexlen) == 0) {
      /* mark this as done once this chunk is transfered */
      data->req.upload_done = TRUE;
    }

    nread+=(int)strlen(endofline_native); /* for the added end of line */
  }
#ifdef CURL_DOES_CONVERSIONS
  else if((data->set.prefer_ascii) && (!sending_http_headers)) {
    CURLcode res;
    res = Curl_convert_to_network(data, data->req.upload_fromhere, nread);
    /* Curl_convert_to_network calls failf if unsuccessful */
    if(res != CURLE_OK)
      return(res);
  }
#endif /* CURL_DOES_CONVERSIONS */

  *nreadp = nread;

  return CURLE_OK;
}

#ifndef CURL_DISABLE_HTTP
/*
 * checkhttpprefix()
 *
 * Returns TRUE if member of the list matches prefix of string
 */
static bool
checkhttpprefix(struct SessionHandle *data,
                const char *s)
{
  struct curl_slist *head = data->set.http200aliases;
  bool rc = FALSE;
#ifdef CURL_DOES_CONVERSIONS
  /* convert from the network encoding using a scratch area */
  char *scratch = calloc(1, strlen(s)+1);
  if(NULL == scratch) {
     failf (data, "Failed to calloc memory for conversion!");
     return FALSE; /* can't return CURLE_OUT_OF_MEMORY so return FALSE */
  }
  strcpy(scratch, s);
  if(CURLE_OK != Curl_convert_from_network(data, scratch, strlen(s)+1)) {
    /* Curl_convert_from_network calls failf if unsuccessful */
     free(scratch);
     return FALSE; /* can't return CURLE_foobar so return FALSE */
  }
  s = scratch;
#endif /* CURL_DOES_CONVERSIONS */

  while(head) {
    if(checkprefix(head->data, s)) {
      rc = TRUE;
      break;
    }
    head = head->next;
  }

  if((rc != TRUE) && (checkprefix("HTTP/", s))) {
    rc = TRUE;
  }

#ifdef CURL_DOES_CONVERSIONS
  free(scratch);
#endif /* CURL_DOES_CONVERSIONS */
  return rc;
}
#endif   /* CURL_DISABLE_HTTP */

/*
 * Curl_readrewind() rewinds the read stream. This is typically used for HTTP
 * POST/PUT with multi-pass authentication when a sending was denied and a
 * resend is necessary.
 */
CURLcode Curl_readrewind(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;

  conn->bits.rewindaftersend = FALSE; /* we rewind now */

  /* explicitly switch off sending data on this connection now since we are
     about to restart a new transfer and thus we want to avoid inadvertently
     sending more data on the existing connection until the next transfer
     starts */
  data->req.keepon &= ~KEEP_SEND;

  /* We have sent away data. If not using CURLOPT_POSTFIELDS or
     CURLOPT_HTTPPOST, call app to rewind
  */
  if(data->set.postfields ||
     (data->set.httpreq == HTTPREQ_POST_FORM))
    ; /* do nothing */
  else {
    if(data->set.seek_func) {
      int err;

      err = (data->set.seek_func)(data->set.seek_client, 0, SEEK_SET);
      if(err) {
        failf(data, "seek callback returned error %d", (int)err);
        return CURLE_SEND_FAIL_REWIND;
      }
    }
    else if(data->set.ioctl_func) {
      curlioerr err;

      err = (data->set.ioctl_func)(data, CURLIOCMD_RESTARTREAD,
                                   data->set.ioctl_client);
      infof(data, "the ioctl callback returned %d\n", (int)err);

      if(err) {
        /* FIXME: convert to a human readable error message */
        failf(data, "ioctl callback returned error %d", (int)err);
        return CURLE_SEND_FAIL_REWIND;
      }
    }
    else {
      /* If no CURLOPT_READFUNCTION is used, we know that we operate on a
         given FILE * stream and we can actually attempt to rewind that
         ourself with fseek() */
      if(data->set.fread_func == (curl_read_callback)fread) {
        if(-1 != fseek(data->set.in, 0, SEEK_SET))
          /* successful rewind */
          return CURLE_OK;
      }

      /* no callback set or failure above, makes us fail at once */
      failf(data, "necessary data rewind wasn't possible");
      return CURLE_SEND_FAIL_REWIND;
    }
  }
  return CURLE_OK;
}

static int data_pending(const struct connectdata *conn)
{
  /* in the case of libssh2, we can never be really sure that we have emptied
     its internal buffers so we MUST always try until we get EAGAIN back */
  return conn->protocol&(PROT_SCP|PROT_SFTP) ||
    Curl_ssl_data_pending(conn, FIRSTSOCKET);
}

static void read_rewind(struct connectdata *conn,
                        size_t thismuch)
{
  DEBUGASSERT(conn->read_pos >= thismuch);

  conn->read_pos -= thismuch;
  conn->bits.stream_was_rewound = TRUE;

#ifdef DEBUGBUILD
  {
    char buf[512 + 1];
    size_t show;

    show = CURLMIN(conn->buf_len - conn->read_pos, sizeof(buf)-1);
    if(conn->master_buffer) {
        memcpy(buf, conn->master_buffer + conn->read_pos, show);
        buf[show] = '\0';
    }
    else {
        buf[0] = '\0';
    }

    DEBUGF(infof(conn->data,
                 "Buffer after stream rewind (read_pos = %d): [%s]",
                 conn->read_pos, buf));
  }
#endif
}


/*
 * Go ahead and do a read if we have a readable socket or if
 * the stream was rewound (in which case we have data in a
 * buffer)
 */
static CURLcode readwrite_data(struct SessionHandle *data,
                               struct connectdata *conn,
                               struct SingleRequest *k,
                               int *didwhat, bool *done)
{
  CURLcode result = CURLE_OK;
  ssize_t nread; /* number of bytes read */
  bool is_empty_data = FALSE;

  *done = FALSE;

  /* This is where we loop until we have read everything there is to
     read or we get a EWOULDBLOCK */
  do {
    size_t buffersize = data->set.buffer_size?
      data->set.buffer_size : BUFSIZE;
    size_t bytestoread = buffersize;
    int readrc;

    if(k->size != -1 && !k->header) {
      /* make sure we don't read "too much" if we can help it since we
         might be pipelining and then someone else might want to read what
         follows! */
      curl_off_t totalleft = k->size - k->bytecount;
      if(totalleft < (curl_off_t)bytestoread)
        bytestoread = (size_t)totalleft;
    }

    if(bytestoread) {
      /* receive data from the network! */
      readrc = Curl_read(conn, conn->sockfd, k->buf, bytestoread, &nread);

      /* subzero, this would've blocked */
      if(0 > readrc)
        break; /* get out of loop */

      /* get the CURLcode from the int */
      result = (CURLcode)readrc;

      if(result>0)
        return result;
    }
    else {
      /* read nothing but since we wanted nothing we consider this an OK
         situation to proceed from */
      nread = 0;
    }

    if((k->bytecount == 0) && (k->writebytecount == 0)) {
      Curl_pgrsTime(data, TIMER_STARTTRANSFER);
      if(k->exp100 > EXP100_SEND_DATA)
        /* set time stamp to compare with when waiting for the 100 */
        k->start100 = Curl_tvnow();
    }

    *didwhat |= KEEP_RECV;
    /* indicates data of zero size, i.e. empty file */
    is_empty_data = (bool)((nread == 0) && (k->bodywrites == 0));

    /* NUL terminate, allowing string ops to be used */
    if(0 < nread || is_empty_data) {
      k->buf[nread] = 0;
    }
    else if(0 >= nread) {
      /* if we receive 0 or less here, the server closed the connection
         and we bail out from this! */
      DEBUGF(infof(data, "nread <= 0, server closed connection, bailing\n"));
      k->keepon &= ~KEEP_RECV;
      break;
    }

    /* Default buffer to use when we write the buffer, it may be changed
       in the flow below before the actual storing is done. */
    k->str = k->buf;

#ifndef CURL_DISABLE_HTTP
    /* Since this is a two-state thing, we check if we are parsing
       headers at the moment or not. */
    if(k->header) {
      /* we are in parse-the-header-mode */
      bool stop_reading = FALSE;
      result = readwrite_http_headers(data, conn, k, &nread, &stop_reading);
      if(result)
        return result;
      if(stop_reading)
        /* We've stopped dealing with input, get out of the do-while loop */
        break;
    }
#endif /* CURL_DISABLE_HTTP */


    /* This is not an 'else if' since it may be a rest from the header
       parsing, where the beginning of the buffer is headers and the end
       is non-headers. */
    if(k->str && !k->header && (nread > 0 || is_empty_data)) {

#ifndef CURL_DISABLE_HTTP
      if(0 == k->bodywrites && !is_empty_data) {
        /* These checks are only made the first time we are about to
           write a piece of the body */
        if(conn->protocol&PROT_HTTP) {
          /* HTTP-only checks */

          if(data->req.newurl) {
            if(conn->bits.close) {
              /* Abort after the headers if "follow Location" is set
                 and we're set to close anyway. */
              k->keepon &= ~KEEP_RECV;
              *done = TRUE;
              return CURLE_OK;
            }
            /* We have a new url to load, but since we want to be able
               to re-use this connection properly, we read the full
               response in "ignore more" */
            k->ignorebody = TRUE;
            infof(data, "Ignoring the response-body\n");
          }
          if(data->state.resume_from && !k->content_range &&
             (data->set.httpreq==HTTPREQ_GET) &&
             !k->ignorebody) {
            /* we wanted to resume a download, although the server doesn't
             * seem to support this and we did this with a GET (if it
             * wasn't a GET we did a POST or PUT resume) */
            failf(data, "HTTP server doesn't seem to support "
                  "byte ranges. Cannot resume.");
            return CURLE_RANGE_ERROR;
          }

          if(data->set.timecondition && !data->state.range) {
            /* A time condition has been set AND no ranges have been
               requested. This seems to be what chapter 13.3.4 of
               RFC 2616 defines to be the correct action for a
               HTTP/1.1 client */
            if((k->timeofdoc > 0) && (data->set.timevalue > 0)) {
              switch(data->set.timecondition) {
              case CURL_TIMECOND_IFMODSINCE:
              default:
                if(k->timeofdoc < data->set.timevalue) {
                  infof(data,
                        "The requested document is not new enough\n");
                  *done = TRUE;
                  data->info.timecond = TRUE;
                  return CURLE_OK;
                }
                break;
              case CURL_TIMECOND_IFUNMODSINCE:
                if(k->timeofdoc > data->set.timevalue) {
                  infof(data,
                        "The requested document is not old enough\n");
                  *done = TRUE;
                  data->info.timecond = TRUE;
                  return CURLE_OK;
                }
                break;
              } /* switch */
            } /* two valid time strings */
          } /* we have a time condition */

        } /* this is HTTP */
      } /* this is the first time we write a body part */
#endif /* CURL_DISABLE_HTTP */
      k->bodywrites++;

      /* pass data to the debug function before it gets "dechunked" */
      if(data->set.verbose) {
        if(k->badheader) {
          Curl_debug(data, CURLINFO_DATA_IN, data->state.headerbuff,
                     (size_t)k->hbuflen, conn);
          if(k->badheader == HEADER_PARTHEADER)
            Curl_debug(data, CURLINFO_DATA_IN,
                       k->str, (size_t)nread, conn);
        }
        else
          Curl_debug(data, CURLINFO_DATA_IN,
                     k->str, (size_t)nread, conn);
      }

#ifndef CURL_DISABLE_HTTP
      if(k->chunk) {
        /*
         * Here comes a chunked transfer flying and we need to decode this
         * properly.  While the name says read, this function both reads
         * and writes away the data. The returned 'nread' holds the number
         * of actual data it wrote to the client.
         */

        CHUNKcode res =
          Curl_httpchunk_read(conn, k->str, nread, &nread);

        if(CHUNKE_OK < res) {
          if(CHUNKE_WRITE_ERROR == res) {
            failf(data, "Failed writing data");
            return CURLE_WRITE_ERROR;
          }
          failf(data, "Received problem %d in the chunky parser", res);
          return CURLE_RECV_ERROR;
        }
        else if(CHUNKE_STOP == res) {
          size_t dataleft;
          /* we're done reading chunks! */
          k->keepon &= ~KEEP_RECV; /* read no more */

          /* There are now possibly N number of bytes at the end of the
             str buffer that weren't written to the client.

             We DO care about this data if we are pipelining.
             Push it back to be read on the next pass. */

          dataleft = conn->chunk.dataleft;
          if(dataleft != 0) {
            infof(conn->data, "Leftovers after chunking. "
                  " Rewinding %d bytes\n",dataleft);
            read_rewind(conn, dataleft);
          }
        }
        /* If it returned OK, we just keep going */
      }
#endif   /* CURL_DISABLE_HTTP */

      if((-1 != k->maxdownload) &&
         (k->bytecount + nread >= k->maxdownload)) {

        if(conn->data->multi && Curl_multi_canPipeline(conn->data->multi)) {
          /* The 'excess' amount below can't be more than BUFSIZE which
             always will fit in a size_t */
          size_t excess = (size_t)(k->bytecount + nread - k->maxdownload);
          if(excess > 0 && !k->ignorebody) {
            infof(data,
                  "Rewinding stream by : %d"
                  " bytes on url %s (size = %" FORMAT_OFF_T
                  ", maxdownload = %" FORMAT_OFF_T
                  ", bytecount = %" FORMAT_OFF_T ", nread = %d)\n",
                  excess, data->state.path,
                  k->size, k->maxdownload, k->bytecount, nread);
            read_rewind(conn, excess);
          }
        }

        nread = (ssize_t) (k->maxdownload - k->bytecount);
        if(nread < 0 ) /* this should be unusual */
          nread = 0;

        k->keepon &= ~KEEP_RECV; /* we're done reading */
      }

      k->bytecount += nread;

      Curl_pgrsSetDownloadCounter(data, k->bytecount);

      if(!k->chunk && (nread || k->badheader || is_empty_data)) {
        /* If this is chunky transfer, it was already written */

        if(k->badheader && !k->ignorebody) {
          /* we parsed a piece of data wrongly assuming it was a header
             and now we output it as body instead */
          result = Curl_client_write(conn, CLIENTWRITE_BODY,
                                     data->state.headerbuff,
                                     k->hbuflen);
          if(result)
            return result;
        }
        if(k->badheader < HEADER_ALLBAD) {
          /* This switch handles various content encodings. If there's an
             error here, be sure to check over the almost identical code
             in http_chunks.c.
             Make sure that ALL_CONTENT_ENCODINGS contains all the
             encodings handled here. */
#ifdef HAVE_LIBZ
          switch (conn->data->set.http_ce_skip ?
                  IDENTITY : k->content_encoding) {
          case IDENTITY:
#endif
            /* This is the default when the server sends no
               Content-Encoding header. See Curl_readwrite_init; the
               memset() call initializes k->content_encoding to zero. */
            if(!k->ignorebody)
              result = Curl_client_write(conn, CLIENTWRITE_BODY, k->str,
                                         nread);
#ifdef HAVE_LIBZ
            break;

          case DEFLATE:
            /* Assume CLIENTWRITE_BODY; headers are not encoded. */
            if(!k->ignorebody)
              result = Curl_unencode_deflate_write(conn, k, nread);
            break;

          case GZIP:
            /* Assume CLIENTWRITE_BODY; headers are not encoded. */
            if(!k->ignorebody)
              result = Curl_unencode_gzip_write(conn, k, nread);
            break;

          case COMPRESS:
          default:
            failf (data, "Unrecognized content encoding type. "
                   "libcurl understands `identity', `deflate' and `gzip' "
                   "content encodings.");
            result = CURLE_BAD_CONTENT_ENCODING;
            break;
          }
#endif
        }
        k->badheader = HEADER_NORMAL; /* taken care of now */

        if(result)
          return result;
      }

    } /* if(! header and data to read ) */

    if(is_empty_data) {
      /* if we received nothing, the server closed the connection and we
         are done */
      k->keepon &= ~KEEP_RECV;
    }

  } while(data_pending(conn));

  if(((k->keepon & (KEEP_RECV|KEEP_SEND)) == KEEP_SEND) &&
     conn->bits.close ) {
    /* When we've read the entire thing and the close bit is set, the server
       may now close the connection. If there's now any kind of sending going
       on from our side, we need to stop that immediately. */
    infof(data, "we are done reading and this is set to close, stop send\n");
    k->keepon &= ~KEEP_SEND; /* no writing anymore either */
  }

  return CURLE_OK;
}

#ifndef CURL_DISABLE_HTTP

/*
 * header_append() copies a chunk of data to the end of the already received
 * header. We make sure that the full string fit in the allocated header
 * buffer, or else we enlarge it.
 */
static CURLcode header_append(struct SessionHandle *data,
                              struct SingleRequest *k,
                              size_t length)
{
  if(k->hbuflen + length >= data->state.headersize) {
    /* We enlarge the header buffer as it is too small */
    char *newbuff;
    size_t hbufp_index;
    size_t newsize;

    if(k->hbuflen + length > CURL_MAX_HTTP_HEADER) {
      /* The reason to have a max limit for this is to avoid the risk of a bad
         server feeding libcurl with a never-ending header that will cause
         reallocs infinitely */
      failf (data, "Avoided giant realloc for header (max is %d)!",
             CURL_MAX_HTTP_HEADER);
      return CURLE_OUT_OF_MEMORY;
    }

    newsize=CURLMAX((k->hbuflen+ length)*3/2, data->state.headersize*2);
    hbufp_index = k->hbufp - data->state.headerbuff;
    newbuff = realloc(data->state.headerbuff, newsize);
    if(!newbuff) {
      failf (data, "Failed to alloc memory for big header!");
      return CURLE_OUT_OF_MEMORY;
    }
    data->state.headersize=newsize;
    data->state.headerbuff = newbuff;
    k->hbufp = data->state.headerbuff + hbufp_index;
  }
  memcpy(k->hbufp, k->str_start, length);
  k->hbufp += length;
  k->hbuflen += length;
  *k->hbufp = 0;

  return CURLE_OK;
}


/*
 * Read any HTTP header lines from the server and pass them to the client app.
 */
static CURLcode readwrite_http_headers(struct SessionHandle *data,
                                       struct connectdata *conn,
                                       struct SingleRequest *k,
                                       ssize_t *nread,
                                       bool *stop_reading)
{
  CURLcode result;

  /* header line within buffer loop */
  do {
    size_t rest_length;
    size_t full_length;
    int writetype;

    /* str_start is start of line within buf */
    k->str_start = k->str;

    /* data is in network encoding so use 0x0a instead of '\n' */
    k->end_ptr = memchr(k->str_start, 0x0a, *nread);

    if(!k->end_ptr) {
      /* Not a complete header line within buffer, append the data to
         the end of the headerbuff. */
      result = header_append(data, k, *nread);
      if(result)
        return result;

      if(!k->headerline && (k->hbuflen>5)) {
        /* make a first check that this looks like a HTTP header */
        if(!checkhttpprefix(data, data->state.headerbuff)) {
          /* this is not the beginning of a HTTP first header line */
          k->header = FALSE;
          k->badheader = HEADER_ALLBAD;
          break;
        }
      }

      break; /* read more and try again */
    }

    /* decrease the size of the remaining (supposed) header line */
    rest_length = (k->end_ptr - k->str)+1;
    *nread -= (ssize_t)rest_length;

    k->str = k->end_ptr + 1; /* move past new line */

    full_length = k->str - k->str_start;

    result = header_append(data, k, full_length);
    if(result)
      return result;

    k->end_ptr = k->hbufp;
    k->p = data->state.headerbuff;

    /****
     * We now have a FULL header line that p points to
     *****/

    if(!k->headerline) {
      /* the first read header */
      if((k->hbuflen>5) &&
         !checkhttpprefix(data, data->state.headerbuff)) {
        /* this is not the beginning of a HTTP first header line */
        k->header = FALSE;
        if(*nread)
          /* since there's more, this is a partial bad header */
          k->badheader = HEADER_PARTHEADER;
        else {
          /* this was all we read so it's all a bad header */
          k->badheader = HEADER_ALLBAD;
          *nread = (ssize_t)rest_length;
        }
        break;
      }
    }

    /* headers are in network encoding so
       use 0x0a and 0x0d instead of '\n' and '\r' */
    if((0x0a == *k->p) || (0x0d == *k->p)) {
      size_t headerlen;
      /* Zero-length header line means end of headers! */

#ifdef CURL_DOES_CONVERSIONS
      if(0x0d == *k->p) {
        *k->p = '\r'; /* replace with CR in host encoding */
        k->p++;       /* pass the CR byte */
      }
      if(0x0a == *k->p) {
        *k->p = '\n'; /* replace with LF in host encoding */
        k->p++;       /* pass the LF byte */
      }
#else
      if('\r' == *k->p)
        k->p++; /* pass the \r byte */
      if('\n' == *k->p)
        k->p++; /* pass the \n byte */
#endif /* CURL_DOES_CONVERSIONS */

      if(100 <= k->httpcode && 199 >= k->httpcode) {
        /*
         * We have made a HTTP PUT or POST and this is 1.1-lingo
         * that tells us that the server is OK with this and ready
         * to receive the data.
         * However, we'll get more headers now so we must get
         * back into the header-parsing state!
         */
        k->header = TRUE;
        k->headerline = 0; /* restart the header line counter */

        /* if we did wait for this do enable write now! */
        if(k->exp100) {
          k->exp100 = EXP100_SEND_DATA;
          k->keepon |= KEEP_SEND;
        }
      }
      else {
        k->header = FALSE; /* no more header to parse! */

        if((k->size == -1) && !k->chunk && !conn->bits.close &&
           (conn->httpversion >= 11) ) {
          /* On HTTP 1.1, when connection is not to get closed, but no
             Content-Length nor Content-Encoding chunked have been
             received, according to RFC2616 section 4.4 point 5, we
             assume that the server will close the connection to
             signal the end of the document. */
          infof(data, "no chunk, no close, no size. Assume close to "
                "signal end\n");
          conn->bits.close = TRUE;
        }
      }

      if(417 == k->httpcode) {
        /*
         * we got: "417 Expectation Failed" this means:
         * we have made a HTTP call and our Expect Header
         * seems to cause a problem => abort the write operations
         * (or prevent them from starting).
         */
        k->exp100 = EXP100_FAILED;
        k->keepon &= ~KEEP_SEND;
      }

      /*
       * When all the headers have been parsed, see if we should give
       * up and return an error.
       */
      if(Curl_http_should_fail(conn)) {
        failf (data, "The requested URL returned error: %d",
               k->httpcode);
        return CURLE_HTTP_RETURNED_ERROR;
      }

      /* now, only output this if the header AND body are requested:
       */
      writetype = CLIENTWRITE_HEADER;
      if(data->set.include_header)
        writetype |= CLIENTWRITE_BODY;

      headerlen = k->p - data->state.headerbuff;

      result = Curl_client_write(conn, writetype,
                                 data->state.headerbuff,
                                 headerlen);
      if(result)
        return result;

      data->info.header_size += (long)headerlen;
      data->req.headerbytecount += (long)headerlen;

      data->req.deductheadercount =
        (100 <= k->httpcode && 199 >= k->httpcode)?data->req.headerbytecount:0;

      if(data->state.resume_from &&
         (data->set.httpreq==HTTPREQ_GET) &&
         (k->httpcode == 416)) {
        /* "Requested Range Not Satisfiable" */
        *stop_reading = TRUE;
      }

      if(!*stop_reading) {
        /* 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 method was picked. */
        result = Curl_http_auth_act(conn);

        if(result)
          return result;

        if(conn->bits.rewindaftersend) {
          /* We rewind after a complete send, so thus we continue
             sending now */
          infof(data, "Keep sending data to get tossed away!\n");
          k->keepon |= KEEP_SEND;
        }
      }

      if(!k->header) {
        /*
         * really end-of-headers.
         *
         * If we requested a "no body", this is a good time to get
         * out and return home.