http.c

             Note that we set the download maximum even if we read a
             "Connection: close" header, to make sure that
             "Content-Length: 0" still prevents us from attempting to
             read the (missing) response-body.
          */
          /* According to RFC2616 section 4.4, we MUST ignore
             Content-Length: headers if we are now receiving data
             using chunked Transfer-Encoding.
          */
          if(k->chunk)
            k->maxdownload = k->size = -1;
        }
        if(-1 != k->size) {
          /* We do this operation even if no_body is true, since this
             data might be retrieved later with curl_easy_getinfo()
             and its CURLINFO_CONTENT_LENGTH_DOWNLOAD option. */

          Curl_pgrsSetDownloadSize(data, k->size);
          k->maxdownload = k->size;
        }

        /* If max download size is *zero* (nothing) we already
           have nothing and can safely return ok now! */
        if(0 == k->maxdownload)
          *stop_reading = TRUE;

        if(*stop_reading) {
          /* we make sure that this socket isn't read more now */
          k->keepon &= ~KEEP_RECV;
        }

        if(data->set.verbose)
          Curl_debug(data, CURLINFO_HEADER_IN,
                     k->str_start, headerlen, conn);
        break;          /* exit header line loop */
      }

      /* We continue reading headers, so reset the line-based
         header parsing variables hbufp && hbuflen */
      k->hbufp = data->state.headerbuff;
      k->hbuflen = 0;
      continue;
    }

    /*
     * Checks for special headers coming up.
     */

    if(!k->headerline++) {
      /* This is the first header, it MUST be the error code line
         or else we consider this to be the body right away! */
      int httpversion_major;
      int rtspversion_major;
      int nc = 0;
#ifdef CURL_DOES_CONVERSIONS
#define HEADER1 scratch
#define SCRATCHSIZE 21
      CURLcode res;
      char scratch[SCRATCHSIZE+1]; /* "HTTP/major.minor 123" */
      /* We can't really convert this yet because we
         don't know if it's the 1st header line or the body.
         So we do a partial conversion into a scratch area,
         leaving the data at k->p as-is.
      */
      strncpy(&scratch[0], k->p, SCRATCHSIZE);
      scratch[SCRATCHSIZE] = 0; /* null terminate */
      res = Curl_convert_from_network(data,
                                      &scratch[0],
                                      SCRATCHSIZE);
      if(res)
        /* Curl_convert_from_network calls failf if unsuccessful */
        return res;
#else
#define HEADER1 k->p /* no conversion needed, just use k->p */
#endif /* CURL_DOES_CONVERSIONS */

      if(conn->handler->protocol & CURLPROTO_HTTP) {
        nc = sscanf(HEADER1,
                    " HTTP/%d.%d %3d",
                    &httpversion_major,
                    &conn->httpversion,
                    &k->httpcode);
        if(nc==3) {
          conn->httpversion += 10 * httpversion_major;
        }
        else {
          /* this is the real world, not a Nirvana
             NCSA 1.5.x returns this crap when asked for HTTP/1.1
          */
          nc=sscanf(HEADER1, " HTTP %3d", &k->httpcode);
          conn->httpversion = 10;

          /* If user has set option HTTP200ALIASES,
             compare header line against list of aliases
          */
          if(!nc) {
            if(checkhttpprefix(data, k->p)) {
              nc = 1;
              k->httpcode = 200;
              conn->httpversion = 10;
            }
          }
        }
      }
      else if(conn->handler->protocol & CURLPROTO_RTSP) {
        nc = sscanf(HEADER1,
                    " RTSP/%d.%d %3d",
                    &rtspversion_major,
                    &conn->rtspversion,
                    &k->httpcode);
        if(nc==3) {
          conn->rtspversion += 10 * rtspversion_major;
          conn->httpversion = 11; /* For us, RTSP acts like HTTP 1.1 */
        }
        else {
          /* TODO: do we care about the other cases here? */
          nc = 0;
        }
      }

      if(nc) {
        data->info.httpcode = k->httpcode;

        data->info.httpversion = conn->httpversion;
        if(!data->state.httpversion ||
           data->state.httpversion > conn->httpversion)
          /* store the lowest server version we encounter */
          data->state.httpversion = conn->httpversion;

        /*
         * This code executes as part of processing the header.  As a
         * result, it's not totally clear how to interpret the
         * response code yet as that depends on what other headers may
         * be present.  401 and 407 may be errors, but may be OK
         * depending on how authentication is working.  Other codes
         * are definitely errors, so give up here.
         */
        if(data->set.http_fail_on_error && (k->httpcode >= 400) &&
           ((k->httpcode != 401) || !conn->bits.user_passwd) &&
           ((k->httpcode != 407) || !conn->bits.proxy_user_passwd) ) {

          if(data->state.resume_from &&
             (data->set.httpreq==HTTPREQ_GET) &&
             (k->httpcode == 416)) {
            /* "Requested Range Not Satisfiable", just proceed and
               pretend this is no error */
          }
          else {
            /* serious error, go home! */
            print_http_error(data);
            return CURLE_HTTP_RETURNED_ERROR;
          }
        }

        if(conn->httpversion == 10) {
          /* Default action for HTTP/1.0 must be to close, unless
             we get one of those fancy headers that tell us the
             server keeps it open for us! */
          infof(data, "HTTP 1.0, assume close after body\n");
          conn->bits.close = TRUE;
        }
        else if(conn->httpversion >= 11 &&
                !conn->bits.close) {
          struct connectbundle *cb_ptr;

          /* If HTTP version is >= 1.1 and connection is persistent
             server supports pipelining. */
          DEBUGF(infof(data,
                       "HTTP 1.1 or later with persistent connection, "
                       "pipelining supported\n"));
          /* Activate pipelining if needed */
          cb_ptr = conn->bundle;
          if(cb_ptr) {
            if(!Curl_pipeline_site_blacklisted(data, conn))
              cb_ptr->server_supports_pipelining = TRUE;
          }
        }

        switch(k->httpcode) {
        case 204:
          /* (quote from RFC2616, section 10.2.5): The server has
           * fulfilled the request but does not need to return an
           * entity-body ... The 204 response MUST NOT include a
           * message-body, and thus is always terminated by the first
           * empty line after the header fields. */
          /* FALLTHROUGH */
        case 304:
          /* (quote from RFC2616, section 10.3.5): The 304 response
           * MUST NOT contain a message-body, and thus is always
           * terminated by the first empty line after the header
           * fields.  */
          if(data->set.timecondition)
            data->info.timecond = TRUE;
          k->size=0;
          k->maxdownload=0;
          k->ignorecl = TRUE; /* ignore Content-Length headers */
          break;
        default:
          /* nothing */
          break;
        }
      }
      else {
        k->header = FALSE;   /* this is not a header line */
        break;
      }
    }

    result = Curl_convert_from_network(data, k->p, strlen(k->p));
    /* Curl_convert_from_network calls failf if unsuccessful */
    if(result)
      return result;

    /* Check for Content-Length: header lines to get size */
    if(!k->ignorecl && !data->set.ignorecl &&
       checkprefix("Content-Length:", k->p)) {
      curl_off_t contentlength = curlx_strtoofft(k->p+15, NULL, 10);
      if(data->set.max_filesize &&
         contentlength > data->set.max_filesize) {
        failf(data, "Maximum file size exceeded");
        return CURLE_FILESIZE_EXCEEDED;
      }
      if(contentlength >= 0) {
        k->size = contentlength;
        k->maxdownload = k->size;
        /* we set the progress download size already at this point
           just to make it easier for apps/callbacks to extract this
           info as soon as possible */
        Curl_pgrsSetDownloadSize(data, k->size);
      }
      else {
        /* Negative Content-Length is really odd, and we know it
           happens for example when older Apache servers send large
           files */
        conn->bits.close = TRUE;
        infof(data, "Negative content-length: %" FORMAT_OFF_T
              ", closing after transfer\n", contentlength);
      }
    }
    /* check for Content-Type: header lines to get the MIME-type */
    else if(checkprefix("Content-Type:", k->p)) {
      char *contenttype = Curl_copy_header_value(k->p);
      if(!contenttype)
        return CURLE_OUT_OF_MEMORY;
      if(!*contenttype)
        /* ignore empty data */
        free(contenttype);
      else {
        Curl_safefree(data->info.contenttype);
        data->info.contenttype = contenttype;
      }
    }
    else if(checkprefix("Server:", k->p)) {
      char *server_name = Curl_copy_header_value(k->p);

      /* Turn off pipelining if the server version is blacklisted */
      if(conn->bundle && conn->bundle->server_supports_pipelining) {
        if(Curl_pipeline_server_blacklisted(data, server_name))
          conn->bundle->server_supports_pipelining = FALSE;
      }
      Curl_safefree(server_name);
    }
    else if((conn->httpversion == 10) &&
            conn->bits.httpproxy &&
            Curl_compareheader(k->p,
                               "Proxy-Connection:", "keep-alive")) {
      /*
       * When a HTTP/1.0 reply comes when using a proxy, the
       * 'Proxy-Connection: keep-alive' line tells us the
       * connection will be kept alive for our pleasure.
       * Default action for 1.0 is to close.
       */
      conn->bits.close = FALSE; /* don't close when done */
      infof(data, "HTTP/1.0 proxy connection set to keep alive!\n");
    }
    else if((conn->httpversion == 11) &&
            conn->bits.httpproxy &&
            Curl_compareheader(k->p,
                               "Proxy-Connection:", "close")) {
      /*
       * We get a HTTP/1.1 response from a proxy and it says it'll
       * close down after this transfer.
       */
      conn->bits.close = TRUE; /* close when done */
      infof(data, "HTTP/1.1 proxy connection set close!\n");
    }
    else if((conn->httpversion == 10) &&
            Curl_compareheader(k->p, "Connection:", "keep-alive")) {
      /*
       * A HTTP/1.0 reply with the 'Connection: keep-alive' line
       * tells us the connection will be kept alive for our
       * pleasure.  Default action for 1.0 is to close.
       *
       * [RFC2068, section 19.7.1] */
      conn->bits.close = FALSE; /* don't close when done */
      infof(data, "HTTP/1.0 connection set to keep alive!\n");
    }
    else if(Curl_compareheader(k->p, "Connection:", "close")) {
      /*
       * [RFC 2616, section 8.1.2.1]
       * "Connection: close" is HTTP/1.1 language and means that
       * the connection will close when this request has been
       * served.
       */
      conn->bits.close = TRUE; /* close when done */
    }
    else if(checkprefix("Transfer-Encoding:", k->p)) {
      /* One or more encodings. We check for chunked and/or a compression
         algorithm. */
      /*
       * [RFC 2616, section 3.6.1] A 'chunked' transfer encoding
       * means that the server will send a series of "chunks". Each
       * chunk starts with line with info (including size of the
       * coming block) (terminated with CRLF), then a block of data
       * with the previously mentioned size. There can be any amount
       * of chunks, and a chunk-data set to zero signals the
       * end-of-chunks. */

      char *start;

      /* Find the first non-space letter */
      start = k->p + 18;

      for(;;) {
        /* skip whitespaces and commas */
        while(*start && (ISSPACE(*start) || (*start == ',')))
          start++;

        if(checkprefix("chunked", start)) {
          k->chunk = TRUE; /* chunks coming our way */

          /* init our chunky engine */
          Curl_httpchunk_init(conn);

          start += 7;
        }

        if(k->auto_decoding)
          /* TODO: we only support the first mentioned compression for now */
          break;

        if(checkprefix("identity", start)) {
          k->auto_decoding = IDENTITY;
          start += 8;
        }
        else if(checkprefix("deflate", start)) {
          k->auto_decoding = DEFLATE;
          start += 7;
        }
        else if(checkprefix("gzip", start)) {
          k->auto_decoding = GZIP;
          start += 4;
        }
        else if(checkprefix("x-gzip", start)) {
          k->auto_decoding = GZIP;
          start += 6;
        }
        else if(checkprefix("compress", start)) {
          k->auto_decoding = COMPRESS;
          start += 8;
        }
        else if(checkprefix("x-compress", start)) {
          k->auto_decoding = COMPRESS;
          start += 10;
        }
        else
          /* unknown! */
          break;

      }

    }
    else if(checkprefix("Content-Encoding:", k->p) &&
            data->set.str[STRING_ENCODING]) {
      /*
       * Process Content-Encoding. Look for the values: identity,
       * gzip, deflate, compress, x-gzip and x-compress. x-gzip and
       * x-compress are the same as gzip and compress. (Sec 3.5 RFC
       * 2616). zlib cannot handle compress.  However, errors are
       * handled further down when the response body is processed
       */
      char *start;

      /* Find the first non-space letter */
      start = k->p + 17;
      while(*start && ISSPACE(*start))
        start++;

      /* Record the content-encoding for later use */
      if(checkprefix("identity", start))
        k->auto_decoding = IDENTITY;
      else if(checkprefix("deflate", start))
        k->auto_decoding = DEFLATE;
      else if(checkprefix("gzip", start)
              || checkprefix("x-gzip", start))
        k->auto_decoding = GZIP;
      else if(checkprefix("compress", start)
              || checkprefix("x-compress", start))
        k->auto_decoding = COMPRESS;
    }
    else if(checkprefix("Content-Range:", k->p)) {
      /* Content-Range: bytes [num]-
         Content-Range: bytes: [num]-
         Content-Range: [num]-

         The second format was added since Sun's webserver
         JavaWebServer/1.1.1 obviously sends the header this way!
         The third added since some servers use that!
      */

      char *ptr = k->p + 14;

      /* Move forward until first digit */
      while(*ptr && !ISDIGIT(*ptr))
        ptr++;

      k->offset = curlx_strtoofft(ptr, NULL, 10);

      if(data->state.resume_from == k->offset)
        /* we asked for a resume and we got it */
        k->content_range = TRUE;
    }
#if !defined(CURL_DISABLE_COOKIES)
    else if(data->cookies &&
            checkprefix("Set-Cookie:", k->p)) {
      Curl_share_lock(data, CURL_LOCK_DATA_COOKIE,
                      CURL_LOCK_ACCESS_SINGLE);
      Curl_cookie_add(data,
                      data->cookies, TRUE, k->p+11,
                      /* If there is a custom-set Host: name, use it
                         here, or else use real peer host name. */
                      conn->allocptr.cookiehost?
                      conn->allocptr.cookiehost:conn->host.name,
                      data->state.path);
      Curl_share_unlock(data, CURL_LOCK_DATA_COOKIE);
    }
#endif
    else if(checkprefix("Last-Modified:", k->p) &&
            (data->set.timecondition || data->set.get_filetime) ) {
      time_t secs=time(NULL);
      k->timeofdoc = curl_getdate(k->p+strlen("Last-Modified:"),
                                  &secs);
      if(data->set.get_filetime)
        data->info.filetime = (long)k->timeofdoc;
    }
    else if((checkprefix("WWW-Authenticate:", k->p) &&
             (401 == k->httpcode)) ||
            (checkprefix("Proxy-authenticate:", k->p) &&
             (407 == k->httpcode))) {

      bool proxy = (k->httpcode == 407) ? TRUE : FALSE;
      char *auth = Curl_copy_header_value(k->p);
      if(!auth)
        return CURLE_OUT_OF_MEMORY;

      result = Curl_http_input_auth(conn, proxy, auth);

      Curl_safefree(auth);

      if(result)
        return result;
    }
    else if((k->httpcode >= 300 && k->httpcode < 400) &&
            checkprefix("Location:", k->p) &&
            !data->req.location) {
      /* this is the URL that the server advises us to use instead */
      char *location = Curl_copy_header_value(k->p);
      if(!location)
        return CURLE_OUT_OF_MEMORY;
      if(!*location)
        /* ignore empty data */
        free(location);
      else {
        data->req.location = location;

        if(data->set.http_follow_location) {
          DEBUGASSERT(!data->req.newurl);
          data->req.newurl = strdup(data->req.location); /* clone */
          if(!data->req.newurl)
            return CURLE_OUT_OF_MEMORY;

          /* some cases of POST and PUT etc needs to rewind the data
             stream at this point */
          result = http_perhapsrewind(conn);
          if(result)
            return result;
        }
      }
    }
    else if(conn->handler->protocol & CURLPROTO_RTSP) {
      result = Curl_rtsp_parseheader(conn, k->p);
      if(result)
        return result;
    }

    /*
     * End of header-checks. Write them to the client.
     */

    writetype = CLIENTWRITE_HEADER;
    if(data->set.include_header)
      writetype |= CLIENTWRITE_BODY;

    if(data->set.verbose)
      Curl_debug(data, CURLINFO_HEADER_IN,
                 k->p, (size_t)k->hbuflen, conn);

    result = Curl_client_write(conn, writetype, k->p, k->hbuflen);
    if(result)
      return result;

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

    /* reset hbufp pointer && hbuflen */
    k->hbufp = data->state.headerbuff;
    k->hbuflen = 0;
  }
  while(!*stop_reading && *k->str); /* header line within buffer */

  /* We might have reached the end of the header part here, but
     there might be a non-header part left in the end of the read
     buffer. */

  return CURLE_OK;
}

#endif /* CURL_DISABLE_HTTP */