transfer.c

#endif
            }
            k->badheader = HEADER_NORMAL; /* taken care of now */

            if(result)
              return result;
          }

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

      } while(!readdone);

    } /* if( read from socket ) */

    /* If we still have writing to do, we check if we have a writable
       socket. Sometimes the writefdp is NULL, if no fd_set was done using
       the multi interface and then we can do nothing but to attempt a
       write to be sure. */
    if((k->keepon & KEEP_WRITE) &&
       (!writefdp || FD_ISSET(conn->writesockfd, writefdp)) ) {
      /* write */

      int i, si;
      ssize_t bytes_written;
      bool writedone=TRUE;

      if ((k->bytecount == 0) && (k->writebytecount == 0))
        Curl_pgrsTime(data, TIMER_STARTTRANSFER);

      didwhat |= KEEP_WRITE;

      /*
       * We loop here to do the READ and SEND loop until we run out of
       * data to send or until we get EWOULDBLOCK back
       */
      do {
        
        /* only read more data if there's no upload data already
           present in the upload buffer */
        if(0 == conn->upload_present) {
          /* init the "upload from here" pointer */
          conn->upload_fromhere = k->uploadbuf;

          if(!k->upload_done) {
            /* HTTP pollution, this should be written nicer to become more
               protocol agnostic. */

            if(k->wait100_after_headers &&
               (conn->proto.http->sending == HTTPSEND_BODY)) {
              /* If this call is to send body data, we must take some action:
                 We have sent off the full HTTP 1.1 request, and we shall now
                 go into the Expect: 100 state and await such a header */
              k->wait100_after_headers = FALSE; /* headers sent */
              k->write_after_100_header = TRUE; /* wait for the header */
              FD_ZERO (&k->writefd);            /* clear it */
              k->wkeepfd = k->writefd;          /* set the keeper variable */
              k->keepon &= ~KEEP_WRITE;         /* disable writing */
              k->start100 = Curl_tvnow();       /* timeout count starts now */
              didwhat &= ~KEEP_WRITE;  /* we didn't write anything actually */
              break;
            }

            nread = fillbuffer(conn, BUFSIZE);
          }
          else
            nread = 0; /* we're done uploading/reading */

          /* the signed int typecase of nread of for systems that has
             unsigned size_t */
          if (nread<=0) {
            /* done */
            k->keepon &= ~KEEP_WRITE; /* we're done writing */
            FD_ZERO(&k->wkeepfd);
            writedone = TRUE;
            break;
          }

          /* store number of bytes available for upload */
          conn->upload_present = nread;

          /* convert LF to CRLF if so asked */
          if (data->set.crlf) {
              if(data->state.scratch == NULL)
                data->state.scratch = malloc(2*BUFSIZE);
              if(data->state.scratch == NULL) {
                failf (data, "Failed to alloc scratch buffer!");
                return CURLE_OUT_OF_MEMORY;
              }
            for(i = 0, si = 0; i < nread; i++, si++) {
              if (conn->upload_fromhere[i] == 0x0a) {
                data->state.scratch[si++] = 0x0d;
                data->state.scratch[si] = 0x0a;
              }
              else
                data->state.scratch[si] = conn->upload_fromhere[i];
            }
            if(si != nread) {
              /* only perform the special operation if we really did replace
                 anything */
              nread = si;

              /* upload from the new (replaced) buffer instead */
              conn->upload_fromhere = data->state.scratch;

              /* set the new amount too */
              conn->upload_present = nread;
            }
          }
        }
        else {
          /* We have a partial buffer left from a previous "round". Use
             that instead of reading more data */
        }

        /* write to socket (send away data) */
        result = Curl_write(conn,
                            conn->writesockfd,     /* socket to send to */
                            conn->upload_fromhere, /* buffer pointer */
                            conn->upload_present,  /* buffer size */
                            &bytes_written);       /* actually send away */
        if(result)
          return result;

        if(data->set.verbose)
          /* show the data before we change the pointer upload_fromhere */
          Curl_debug(data, CURLINFO_DATA_OUT, conn->upload_fromhere,
                     bytes_written);
      
        if(conn->upload_present != bytes_written) {
          /* we only wrote a part of the buffer (if anything), deal with it! */

          /* store the amount of bytes left in the buffer to write */
          conn->upload_present -= bytes_written;

          /* advance the pointer where to find the buffer when the next send
             is to happen */
          conn->upload_fromhere += bytes_written;

          writedone = TRUE; /* we are done, stop the loop */
        }
        else {
          /* we've uploaded that buffer now */
          conn->upload_fromhere = k->uploadbuf;
          conn->upload_present = 0; /* no more bytes left */

          if(k->upload_done) {
            /* switch off writing, we're done! */
            k->keepon &= ~KEEP_WRITE; /* we're done writing */
            FD_ZERO(&k->wkeepfd);
            writedone = TRUE;
          }
        }

        k->writebytecount += bytes_written;
        Curl_pgrsSetUploadCounter(data, (double)k->writebytecount);

      } while(!writedone); /* loop until we're done writing! */
      
    }

  } while(0); /* just to break out from! */

  k->now = Curl_tvnow();
  if(didwhat) {
    /* Update read/write counters */
    if(conn->bytecountp)
      *conn->bytecountp = k->bytecount; /* read count */
    if(conn->writebytecountp)
      *conn->writebytecountp = k->writebytecount; /* write count */
  }
  else {
    /* no read no write, this is a timeout? */
    if (k->write_after_100_header) {
      /* This should allow some time for the header to arrive, but only a
         very short time as otherwise it'll be too much wasted times too
         often. */

      /* Quoting RFC2616, section "8.2.3 Use of the 100 (Continue) Status":
         
      Therefore, when a client sends this header field to an origin server
      (possibly via a proxy) from which it has never seen a 100 (Continue)
      status, the client SHOULD NOT wait for an indefinite period before
      sending the request body.

      */

      int ms = Curl_tvdiff(k->now, k->start100);
      if(ms > CURL_TIMEOUT_EXPECT_100) {
        /* we've waited long enough, continue anyway */
        k->write_after_100_header = FALSE;
        FD_SET (conn->writesockfd, &k->writefd); /* write socket */
        k->keepon |= KEEP_WRITE;
        k->wkeepfd = k->writefd;
      }
    }    
  }

  if(Curl_pgrsUpdate(conn))
    result = CURLE_ABORTED_BY_CALLBACK;
  else
    result = Curl_speedcheck (data, k->now);
  if (result)
    return result;
    
  if (data->set.timeout &&
      ((Curl_tvdiff(k->now, k->start)/1000) >= data->set.timeout)) {
    failf (data, "Operation timed out with %d out of %d bytes received",
           k->bytecount, conn->size);
    return CURLE_OPERATION_TIMEOUTED;
  }

  if(!k->keepon) {
    /*
     * The transfer has been performed. Just make some general checks before
     * returning.
     */

    if(!(data->set.no_body) && k->contentlength &&
       (k->bytecount != k->contentlength) &&
       !conn->newurl) {
      failf(data, "transfer closed with %d bytes remaining to read",
            k->contentlength-k->bytecount);
      return CURLE_PARTIAL_FILE;
    }
    else if(conn->bits.chunk && conn->proto.http->chunk.datasize) {
      failf(data, "transfer closed with at least %d bytes remaining",
            conn->proto.http->chunk.datasize);
      return CURLE_PARTIAL_FILE;
    }
    if(Curl_pgrsUpdate(conn))
      return CURLE_ABORTED_BY_CALLBACK;
  }

  /* Now update the "done" boolean we return */
  *done = !k->keepon;

  return CURLE_OK;
}

CURLcode Curl_readwrite_init(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  struct Curl_transfer_keeper *k = &conn->keep;

  /* NB: the content encoding software depends on this initialization of
     Curl_transfer_keeper. 08/28/02 jhrg */
  memset(k, 0, sizeof(struct Curl_transfer_keeper));

  k->start = Curl_tvnow(); /* start time */
  k->now = k->start;   /* current time is now */
  k->header = TRUE; /* assume header */
  k->httpversion = -1; /* unknown at this point */

  data = conn->data; /* there's the root struct */
  k->buf = data->state.buffer;
  k->uploadbuf = data->state.uploadbuffer;
  k->maxfd = (conn->sockfd>conn->writesockfd?
              conn->sockfd:conn->writesockfd)+1;
  k->hbufp = data->state.headerbuff;
  k->ignorebody=FALSE;

  Curl_pgrsTime(data, TIMER_PRETRANSFER);
  Curl_speedinit(data);

  Curl_pgrsSetUploadCounter(data, 0);
  Curl_pgrsSetDownloadCounter(data, 0);

  if (!conn->bits.getheader) {
    k->header = FALSE;
    if(conn->size > 0)
      Curl_pgrsSetDownloadSize(data, conn->size);
  }
  /* we want header and/or body, if neither then don't do this! */
  if(conn->bits.getheader || !data->set.no_body) {

    FD_ZERO (&k->readfd);               /* clear it */
    if(conn->sockfd != -1) {
      FD_SET (conn->sockfd, &k->readfd); /* read socket */
      k->keepon |= KEEP_READ;
    }

    FD_ZERO (&k->writefd);              /* clear it */
    if(conn->writesockfd != -1) {
      /* HTTP 1.1 magic:

         Even if we require a 100-return code before uploading data, we might
         need to write data before that since the REQUEST may not have been
         finished sent off just yet.

         Thus, we must check if the request has been sent before we set the
         state info where we wait for the 100-return code
      */
      if (data->set.expect100header &&
          (conn->proto.http->sending == HTTPSEND_BODY)) {
        /* wait with write until we either got 100-continue or a timeout */
        k->write_after_100_header = TRUE;
        k->start100 = k->start;
      }
      else {
        if(data->set.expect100header)
          /* when we've sent off the rest of the headers, we must await a
             100-continue */
          k->wait100_after_headers = TRUE;
        FD_SET (conn->writesockfd, &k->writefd); /* write socket */
        k->keepon |= KEEP_WRITE;
      }
    }

    /* get these in backup variables to be able to restore them on each lap in
       the select() loop */
    k->rkeepfd = k->readfd;
    k->wkeepfd = k->writefd;

  }

  return CURLE_OK;
}

void Curl_single_fdset(struct connectdata *conn,
                       fd_set *read_fd_set,
                       fd_set *write_fd_set,
                       fd_set *exc_fd_set,
                       int *max_fd)
{
  *max_fd = -1; /* init */
  if(conn->keep.keepon & KEEP_READ) {
    FD_SET(conn->sockfd, read_fd_set);
    *max_fd = conn->sockfd;
    conn->keep.readfdp = read_fd_set; /* store the address of the set */
  }
  if(conn->keep.keepon & KEEP_WRITE) {
    FD_SET(conn->writesockfd, write_fd_set);
    if(conn->writesockfd > *max_fd)
      *max_fd = conn->writesockfd;
    conn->keep.writefdp = write_fd_set; /* store the address of the set */
  }
  /* we don't use exceptions, only touch that one to prevent compiler
     warnings! */
  *exc_fd_set = *exc_fd_set;
}


/*
 * Transfer()
 *
 * This function is what performs the actual transfer. It is capable of
 * doing both ways simultaneously.
 * The transfer must already have been setup by a call to Curl_Transfer().
 *
 * Note that headers are created in a preallocated buffer of a default size.
 * That buffer can be enlarged on demand, but it is never shrinken again.
 *
 * Parts of this function was once written by the friendly Mark Butler
 * <butlerm@xmission.com>.
 */

static CURLcode
Transfer(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  CURLcode result;
  struct Curl_transfer_keeper *k = &conn->keep;
  bool done=FALSE;

  Curl_readwrite_init(conn);

  if((conn->sockfd == -1) && (conn->writesockfd == -1))
    /* nothing to read, nothing to write, we're already OK! */
    return CURLE_OK;

  /* we want header and/or body, if neither then don't do this! */
  if(!conn->bits.getheader && data->set.no_body)
    return CURLE_OK;

  k->writefdp = &k->writefd; /* store the address of the set */
  k->readfdp = &k->readfd;   /* store the address of the set */

  while (!done) {
    struct timeval interval;
    k->readfd = k->rkeepfd;  /* set these every lap in the loop */
    k->writefd = k->wkeepfd;
    interval.tv_sec = 1;
    interval.tv_usec = 0;

    switch (select (k->maxfd, k->readfdp, k->writefdp, NULL, &interval)) {
    case -1: /* select() error, stop reading */
#ifdef EINTR
      /* The EINTR is not serious, and it seems you might get this more
         ofen when using the lib in a multi-threaded environment! */
      if(errno == EINTR)
        ;
      else
#endif
        done = TRUE; /* no more read or write */
      continue;
    case 0:  /* timeout */
    default: /* readable descriptors */
      result = Curl_readwrite(conn, &done);
      break;
    }
    if(result)
      return result;
    
    /* "done" signals to us if the transfer(s) are ready */
  }

  return CURLE_OK;
}

CURLcode Curl_pretransfer(struct SessionHandle *data)
{
  CURLcode res;
  if(!data->change.url)
    /* we can't do anything wihout URL */
    return CURLE_URL_MALFORMAT;

#ifdef USE_SSLEAY
  /* Init the SSL session ID cache here. We do it here since we want to
     do it after the *_setopt() calls (that could change the size) but
     before any transfer. */
  res = Curl_SSL_InitSessions(data, data->set.ssl.numsessions);
  if(res)
    return res;
#else
  (void)res;
#endif

  data->set.followlocation=0; /* reset the location-follow counter */
  data->state.this_is_a_follow = FALSE; /* reset this */
  data->state.errorbuf = FALSE; /* no error has occurred */

  /* set preferred authentication, default to basic */

  data->state.authstage = 0; /* initialize authentication later */

  /* If there was a list of cookie files to read and we haven't done it before,
     do it now! */
  if(data->change.cookielist) {
    struct curl_slist *list = data->change.cookielist;
    Curl_share_lock(data, CURL_LOCK_DATA_COOKIE, CURL_LOCK_ACCESS_SINGLE);
    while(list) {
      data->cookies = Curl_cookie_init(data,
                                       list->data,
                                       data->cookies,
                                       data->set.cookiesession);
      list = list->next;
    }
    Curl_share_unlock(data, CURL_LOCK_DATA_COOKIE);
    curl_slist_free_all(data->change.cookielist); /* clean up list */
    data->change.cookielist = NULL; /* don't do this again! */
  }



 /* Allow data->set.use_port to set which port to use. This needs to be
  * disabled for example when we follow Location: headers to URLs using
  * different ports! */
  data->state.allow_port = TRUE;

#if defined(HAVE_SIGNAL) && defined(SIGPIPE)
  /*************************************************************
   * Tell signal handler to ignore SIGPIPE
   *************************************************************/
  if(!data->set.no_signal)
    data->state.prev_signal = signal(SIGPIPE, SIG_IGN);
#endif  

  Curl_initinfo(data); /* reset session-specific information "variables" */
  Curl_pgrsStartNow(data);

  return CURLE_OK;
}

CURLcode Curl_posttransfer(struct SessionHandle *data)
{
#if defined(HAVE_SIGNAL) && defined(SIGPIPE)
  /* restore the signal handler for SIGPIPE before we get back */
  if(!data->set.no_signal)
    signal(SIGPIPE, data->state.prev_signal);
#endif  

  return CURLE_OK;
}

static int strlen_url(char *url)
{
  char *ptr;
  int newlen=0;
  bool left=TRUE; /* left side of the ? */

  for(ptr=url; *ptr; ptr++) {
    switch(*ptr) {
    case '?':
      left=FALSE;
    default:
      newlen++;
      break;
    case ' ':
      if(left)
        newlen+=3;
      else
        newlen++;
      break;
    }
  }
  return newlen;
}

static void strcpy_url(char *output, char *url)
{
  /* we must add this with whitespace-replacing */
  bool left=TRUE;
  char *iptr;
  char *optr = output;
  for(iptr = url;    /* read from here */
      *iptr;         /* until zero byte */
      iptr++) {
    switch(*iptr) {
    case '?':
      left=FALSE;
    default:
      *optr++=*iptr;
      break;
    case ' ':
      if(left) {
        *optr++='%'; /* add a '%' */
        *optr++='2'; /* add a '2' */
        *optr++='0'; /* add a '0' */
      }
      else
        *optr++='+'; /* add a '+' here */
      break;
    }
  }
  *optr=0; /* zero terminate output buffer */

}

CURLcode Curl_follow(struct SessionHandle *data,
                     char *newurl) /* this 'newurl' is the Location: string,
                                      and it must be malloc()ed before passed
                                      here */
{
  /* Location: redirect */
  char prot[16]; /* URL protocol string storage */
  char letter;   /* used for a silly sscanf */
  int newlen;
  char *newest;
  
  if (data->set.maxredirs &&
      (data->set.followlocation >= data->set.maxredirs)) {
    failf(data,"Maximum (%d) redirects followed", data->set.maxredirs);
    return CURLE_TOO_MANY_REDIRECTS;
  }

  /* mark the next request as a followed location: */
  data->state.this_is_a_follow = TRUE;

  data->set.followlocation++; /* count location-followers */

  if(data->set.http_auto_referer) {
    /* We are asked to automatically set the previous URL as the
       referer when we get the next URL. We pick the ->url field,
       which may or may not be 100% correct */

    if(data->change.referer_alloc)
      /* If we already have an allocated referer, free this first */
      free(data->change.referer);

    data->change.referer = strdup(data->change.url);
    data->change.referer_alloc = TRUE; /* yes, free this later */
  }

  if(2 != sscanf(newurl, "%15[^?&/:]://%c", prot, &letter)) {
    /***
     *DANG* this is an RFC 2068 violation. The URL is supposed
     to be absolute and this doesn't seem to be that!
     ***
     Instead, we have to TRY to append this new path to the old URL
     to the right of the host part. Oh crap, this is doomed to cause
     problems in the future...
    */
    char *protsep;
    char *pathsep;

    char *useurl = newurl;
    int urllen;

    /* we must make our own copy of the URL to play with, as it may
       point to read-only data */
    char *url_clone=strdup(data->change.url);

    if(!url_clone)
      return CURLE_OUT_OF_MEMORY; /* skip out of this NOW */

    /* protsep points to the start of the host name */
    protsep=strstr(url_clone, "//");
    if(!protsep)
      protsep=url_clone;
    else
      protsep+=2; /* pass the slashes */

    if('/' != newurl[0]) {
      int level=0;

      /* First we need to find out if there's a ?-letter in the URL,
         and cut it and the right-side of that off */
      pathsep = strrchr(protsep, '?');
      if(pathsep)
        *pathsep=0;
      
      /* we have a relative path to append to the last slash if
         there's one available */
      pathsep = strrchr(protsep, '/');
      if(pathsep)
        *pathsep=0;

      /* Check if there's any slash after the host name, and if so,
         remember that position instead */
      pathsep = strchr(protsep, '/');
      if(pathsep)
        protsep = pathsep+1;
      else
        protsep = NULL;

      /* now deal with one "./" or any amount of "../" in the newurl
         and act accordingly */

      if((useurl[0] == '.') && (useurl[1] == '/'))
        useurl+=2; /* just skip the "./" */
            
      while((useurl[0] == '.') &&
            (useurl[1] == '.') &&
            (useurl[2] == '/')) {
        level++; 
        useurl+=3; /* pass the "../" */
      }

      if(protsep) {
        while(level--) {
          /* cut off one more level from the right of the original URL */
          pathsep = strrchr(protsep, '/');
          if(pathsep)
            *pathsep=0;
          else {
            *protsep=0;
            break;
          }
        }
      }
    }
    else {
      /* We got a new absolute path for this server, cut off from the
         first slash */
      pathsep = strchr(protsep, '/');
      if(pathsep)
        *pathsep=0;
    }

    /* If the new part contains a space, this is a mighty stupid redirect
       but we still make an effort to do "right". To the left of a '?'
       letter we replace each space with %20 while it is replaced with '+'
       on the right side of the '?' letter.
    */
    newlen = strlen_url(useurl);

    urllen = strlen(url_clone);
    
    newest=(char *)malloc( urllen + 1 + /* possible slash */
                           newlen + 1 /* zero byte */);
    
    if(!newest)
      return CURLE_OUT_OF_MEMORY; /* go out from this */

    /* copy over the root url part */
    memcpy(newest, url_clone, urllen);

    /* check if we need to append a slash */
    if(('/' == useurl[0]) || (protsep && !*protsep))
      ;
    else
      newest[urllen++]='/';

    /* then append the new piece on the right side */
    strcpy_url(&newest[urllen], useurl);

    free(newurl); /* newurl is the allocated pointer */
    free(url_clone);
    newurl = newest;
  }
  else {
    /* This is an absolute URL, don't allow the custom port number */
    data->state.allow_port = FALSE;

    if(strchr(newurl, ' ')) {
      /* This new URL contains at least one space, this is a mighty stupid
         redirect but we still make an effort to do "right". */
      newlen = strlen_url(newurl);

      newest = malloc(newlen+1); /* get memory for this */
      if(newest) {
        strcpy_url(newest, newurl); /* create a space-free URL */

        free(newurl); /* that was no good */
        newurl = newest; /* use this instead now */
      }
    }

  }

  if(data->change.url_alloc)
    free(data->change.url);
  else
    data->change.url_alloc = TRUE; /* the URL is allocated */
      
  data->change.url = newurl;
  newurl = NULL; /* don't free! */

  infof(data, "Issue another request to this URL: '%s'\n", data->change.url);

  /*
   * We get here when the HTTP code is 300-399 (and 401). We need to perform
   * differently based on exactly what return code there was.
   *
   * News from 7.10.6: we can also get here on a 401, in case we act on a
   * HTTP authentication scheme other than Basic.
   */
  switch(data->info.httpcode) {
  case 401:
    /* Act on an authentication, we keep on moving and do the Authorization:
       XXXX header in the HTTP request code snippet */
    break;
  case 300: /* Multiple Choices */
  case 306: /* Not used */
  case 307: /* Temporary Redirect */
  default:  /* for all unknown ones */
    /* These are explicitly mention since I've checked RFC2616 and they
     * seem to be OK to POST to.
     */
    break;
  case 301: /* Moved Permanently */
    /* (quote from RFC2616, section 10.3.2):
     * 
     *  Note: When automatically redirecting a POST request after
     *  receiving a 301 status code, some existing HTTP/1.0 user agents
     *  will erroneously change it into a GET request.
     *
     * ----
     * Warning: Because most of importants user agents do this clear
     * RFC2616 violation, many webservers expect this misbehavior. So
     * these servers often answers to a POST request with an error page.
     * To be sure that libcurl gets the page that most user agents
     * would get, libcurl has to force GET:
     */
    if( data->set.httpreq == HTTPREQ_POST
        || data->set.httpreq == HTTPREQ_POST_FORM) {
      infof(data,
            "Violate RFC 2616/10.3.2 and switch from POST to GET\n");
      data->set.httpreq = HTTPREQ_GET;
    }
    break;
  case 302: /* Found */
    /* (From 10.3.3)
       
    Note: RFC 1945 and RFC 2068 specify that the client is not allowed
    to change the method on the redirected request.  However, most
    existing user agent implementations treat 302 as if it were a 303
    response, performing a GET on the Location field-value regardless
    of the original request method. The status codes 303 and 307 have
    been added for servers that wish to make unambiguously clear which
    kind of reaction is expected of the client.
    
    (From 10.3.4)
    
    Note: Many pre-HTTP/1.1 user agents do not understand the 303
    status. When interoperability with such clients is a concern, the
    302 status code may be used instead, since most user agents react
    to a 302 response as described here for 303.             
    */
  case 303: /* See Other */
    /* Disable both types of POSTs, since doing a second POST when
     * following isn't what anyone would want! */
    if(data->set.httpreq != HTTPREQ_GET) {
      data->set.httpreq = HTTPREQ_GET; /* enforce GET request */
      infof(data, "Disables POST, goes with %s\n",
            data->set.no_body?"HEAD":"GET");
    }
    break;
  case 304: /* Not Modified */
    /* 304 means we did a conditional request and it was "Not modified".
     * We shouldn't get any Location: header in this response!
     */
    break;
  case 305: /* Use Proxy */
    /* (quote from RFC2616, section 10.3.6):
     * "The requested resource MUST be accessed through the proxy given
     * by the Location field. The Location field gives the URI of the
     * proxy.  The recipient is expected to repeat this single request
     * via the proxy. 305 responses MUST only be generated by origin
     * servers."
     */
    break;
  }
  Curl_pgrsTime(data, TIMER_REDIRECT);
  Curl_pgrsResetTimes(data);

  return CURLE_OK;
}

CURLcode Curl_perform(struct SessionHandle *data)
{
  CURLcode res;
  CURLcode res2;
  struct connectdata *conn=NULL;
  char *newurl = NULL; /* possibly a new URL to follow to! */

  data->state.used_interface = Curl_if_easy;

  res = Curl_pretransfer(data);
  if(res)
    return res;

  /*
   * It is important that there is NO 'return' from this function at any other
   * place than falling down to the end of the function! This is because we
   * have cleanup stuff that must be done before we get back, and that is only
   * performed after this do-while loop.
   */

  do {  
    int urlchanged = FALSE;
    do {
      bool async;
      Curl_pgrsTime(data, TIMER_STARTSINGLE);
      data->change.url_changed = FALSE;
      res = Curl_connect(data, &conn, &async);

      if((CURLE_OK == res) && async) {
        /* Now, if async is TRUE here, we need to wait for the name
           to resolve */
        res = Curl_wait_for_resolv(conn, NULL);
        if(CURLE_OK == res)
          /* Resolved, continue with the connection */
          res = Curl_async_resolved(conn);              
      }
      if(res)
        break;
      
      /* If a callback (or something) has altered the URL we should use within
         the Curl_connect(), we detect it here and act as if we are redirected
         to the new URL */
      urlchanged = data->change.url_changed;
      if ((CURLE_OK == res) && urlchanged) {
        res = Curl_done(conn);
        if(CURLE_OK == res) {
          char *gotourl = strdup(data->change.url);
          res = Curl_follow(data, gotourl);
          if(res)
            free(gotourl);
        }
      }
    } while (urlchanged && res == CURLE_OK) ; 

    if(res == CURLE_OK) {
      res = Curl_do(&conn);

      if(res == CURLE_OK) {
        if(conn->protocol&PROT_FTPS)
          /* FTPS, disable ssl while transfering data */
          conn->ssl.use = FALSE;
        res = Transfer(conn); /* now fetch that URL please */
        if(conn->protocol&PROT_FTPS)
          /* FTPS, enable ssl again after havving transferred data */
          conn->ssl.use = TRUE;

        if(res == CURLE_OK)
          /*
           * We must duplicate the new URL here as the connection data
           * may be free()ed in the Curl_done() function.
           */
          newurl = conn->newurl?strdup(conn->newurl):NULL;
        else {
          /* The transfer phase returned error, we mark the connection to get
           * closed to prevent being re-used. This is becasue we can't
           * possibly know if the connection is in a good shape or not now. */
          conn->bits.close = TRUE;

          if(-1 !=conn->secondarysocket) {
            /* if we failed anywhere, we must clean up the secondary socket if
               it was used */
            sclose(conn->secondarysocket);
            conn->secondarysocket=-1;
          }
        }

        /* Always run Curl_done(), even if some of the previous calls
           failed, but return the previous (original) error code */
        res2 = Curl_done(conn);

        if(CURLE_OK == res)
          res = res2;
      }

      /*
       * Important: 'conn' cannot be used here, since it may have been closed
       * in 'Curl_done' or other functions.
       */

      if((res == CURLE_OK) && newurl) {
        res = Curl_follow(data, newurl);
        if(CURLE_OK == res) {
          newurl = NULL;
          continue;
        }
      }
    }
    break; /* it only reaches here when this shouldn't loop */

  } while(1); /* loop if Location: */

  if(newurl)
    free(newurl);

  /* run post-transfer uncondionally, but don't clobber the return code if
     we already have an error code recorder */
  res2 = Curl_posttransfer(data);
  if(!res && res2)
    res = res2;

  return res;
}

CURLcode 
Curl_Transfer(struct connectdata *c_conn, /* connection data */
              int sockfd,       /* socket to read from or -1 */
              int size,         /* -1 if unknown at this point */
              bool getheader,   /* TRUE if header parsing is wanted */
              long *bytecountp, /* return number of bytes read or NULL */
              int writesockfd,  /* socket to write to, it may very well be
                                   the same we read from. -1 disables */
              long *writebytecountp /* return number of bytes written or
                                       NULL */
              )
{
  struct connectdata *conn = (struct connectdata *)c_conn;
  if(!conn)
    return CURLE_BAD_FUNCTION_ARGUMENT;

  /* now copy all input parameters */
  conn->sockfd = sockfd;
  conn->size = size;
  conn->bits.getheader = getheader;
  conn->bytecountp = bytecountp;
  conn->writesockfd = writesockfd;
  conn->writebytecountp = writebytecountp;

  return CURLE_OK;

}