url.c

   * Setup whatever necessary for a resumed transfer
   */
  result = setup_range(data);
  if(result)
    return result;

  /* Continue connectdata initialization here. */

  /*
   * Inherit the proper values from the urldata struct AFTER we have arranged
   * the persistent connection stuff
   */
  conn->fread_func = data->set.fread_func;
  conn->fread_in = data->set.in;
  conn->seek_func = data->set.seek_func;
  conn->seek_client = data->set.seek_client;

  /*************************************************************
   * Resolve the address of the server or proxy
   *************************************************************/
  result = resolve_server(data, conn, async);

  return result;
}

/* setup_conn() is called after the name resolve initiated in
 * create_conn() is all done.
 *
 * setup_conn() also handles reused connections
 *
 * conn->data MUST already have been setup fine (in create_conn)
 */

static CURLcode setup_conn(struct connectdata *conn,
                           bool *protocol_done)
{
  CURLcode result=CURLE_OK;
  struct SessionHandle *data = conn->data;

  Curl_pgrsTime(data, TIMER_NAMELOOKUP);

  if(conn->handler->protocol & PROT_FILE) {
    /* There's nothing in this function to setup if we're only doing
       a file:// transfer */
    *protocol_done = TRUE;
    return result;
  }
  *protocol_done = FALSE; /* default to not done */

  /* set proxy_connect_closed to false unconditionally already here since it
     is used strictly to provide extra information to a parent function in the
     case of proxy CONNECT failures and we must make sure we don't have it
     lingering set from a previous invoke */
  conn->bits.proxy_connect_closed = FALSE;

  /*
   * Set user-agent. Used for HTTP, but since we can attempt to tunnel
   * basically anything through a http proxy we can't limit this based on
   * protocol.
   */
  if(data->set.str[STRING_USERAGENT]) {
    Curl_safefree(conn->allocptr.uagent);
    conn->allocptr.uagent =
      aprintf("User-Agent: %s\r\n", data->set.str[STRING_USERAGENT]);
    if(!conn->allocptr.uagent)
      return CURLE_OUT_OF_MEMORY;
  }

  data->req.headerbytecount = 0;

#ifdef CURL_DO_LINEEND_CONV
  data->state.crlf_conversions = 0; /* reset CRLF conversion counter */
#endif /* CURL_DO_LINEEND_CONV */

  for(;;) {
    /* loop for CURL_SERVER_CLOSED_CONNECTION */

    if(CURL_SOCKET_BAD == conn->sock[FIRSTSOCKET]) {
      /* Try to connect only if not already connected */
      bool connected = FALSE;

      result = ConnectPlease(data, conn, &connected);

      if(connected) {
        result = Curl_protocol_connect(conn, protocol_done);
        if(CURLE_OK == result)
          conn->bits.tcpconnect = TRUE;
      }
      else
        conn->bits.tcpconnect = FALSE;

      /* if the connection was closed by the server while exchanging
         authentication informations, retry with the new set
         authentication information */
      if(conn->bits.proxy_connect_closed) {
        /* reset the error buffer */
        if(data->set.errorbuffer)
          data->set.errorbuffer[0] = '\0';
        data->state.errorbuf = FALSE;
        continue;
      }

      if(CURLE_OK != result)
        return result;
    }
    else {
      Curl_pgrsTime(data, TIMER_CONNECT); /* we're connected already */
      Curl_pgrsTime(data, TIMER_APPCONNECT); /* we're connected already */
      conn->bits.tcpconnect = TRUE;
      *protocol_done = TRUE;
      Curl_verboseconnect(conn);
      Curl_updateconninfo(conn, conn->sock[FIRSTSOCKET]);
    }
    /* Stop the loop now */
    break;
  }

  conn->now = Curl_tvnow(); /* time this *after* the connect is done, we
                               set this here perhaps a second time */

#ifdef __EMX__
  /*
   * This check is quite a hack. We're calling _fsetmode to fix the problem
   * with fwrite converting newline characters (you get mangled text files,
   * and corrupted binary files when you download to stdout and redirect it to
   * a file).
   */

  if((data->set.out)->_handle == NULL) {
    _fsetmode(stdout, "b");
  }
#endif

  return result;
}

CURLcode Curl_connect(struct SessionHandle *data,
                      struct connectdata **in_connect,
                      bool *asyncp,
                      bool *protocol_done)
{
  CURLcode code;

  *asyncp = FALSE; /* assume synchronous resolves by default */

  /* call the stuff that needs to be called */
  code = create_conn(data, in_connect, asyncp);

  if(CURLE_OK == code) {
    /* no error */
    if((*in_connect)->send_pipe->size || (*in_connect)->recv_pipe->size)
      /* pipelining */
      *protocol_done = TRUE;
    else if (!*asyncp) {
      /* DNS resolution is done: that's either because this is a reused
         connection, in which case DNS was unnecessary, or because DNS
         really did finish already (synch resolver/fast async resolve) */
      code = setup_conn(*in_connect, protocol_done);
    }
  }

  if(code && *in_connect) {
    /* We're not allowed to return failure with memory left allocated
       in the connectdata struct, free those here */
    Curl_disconnect(*in_connect, FALSE); /* close the connection */
    *in_connect = NULL;           /* return a NULL */
  }

  return code;
}

/* Call this function after Curl_connect() has returned async=TRUE and
   then a successful name resolve has been received.

   Note: this function disconnects and frees the conn data in case of
   resolve failure */
CURLcode Curl_async_resolved(struct connectdata *conn,
                             bool *protocol_done)
{
#ifdef CURLRES_ASYNCH
  CURLcode code;

  if(conn->async.dns) {
    conn->dns_entry = conn->async.dns;
    conn->async.dns = NULL;
  }

  code = setup_conn(conn, protocol_done);

  if(code)
    /* We're not allowed to return failure with memory left allocated
       in the connectdata struct, free those here */
    Curl_disconnect(conn, FALSE); /* close the connection */

  return code;
#else
  (void)conn;
  (void)protocol_done;
  return CURLE_OK;
#endif
}


CURLcode Curl_done(struct connectdata **connp,
                   CURLcode status,  /* an error if this is called after an
                                        error was detected */
                   bool premature)
{
  CURLcode result;
  struct connectdata *conn;
  struct SessionHandle *data;

  DEBUGASSERT(*connp);

  conn = *connp;
  data = conn->data;

  if(conn->bits.done)
    /* Stop if Curl_done() has already been called */
    return CURLE_OK;

  Curl_getoff_all_pipelines(data, conn);

  if((conn->send_pipe->size + conn->recv_pipe->size != 0 &&
      !data->set.reuse_forbid &&
      !conn->bits.close))
    /* Stop if pipeline is not empty and we do not have to close
       connection. */
    return CURLE_OK;

  conn->bits.done = TRUE; /* called just now! */

  /* Cleanup possible redirect junk */
  if(data->req.newurl) {
    free(data->req.newurl);
    data->req.newurl = NULL;
  }
  if(data->req.location) {
    free(data->req.location);
    data->req.location = NULL;
  }

  Curl_async_cancel(conn);

  if(conn->dns_entry) {
    Curl_resolv_unlock(data, conn->dns_entry); /* done with this */
    conn->dns_entry = NULL;
  }

  /* this calls the protocol-specific function pointer previously set */
  if(conn->handler->done)
    result = conn->handler->done(conn, status, premature);
  else
    result = CURLE_OK;

  Curl_pgrsDone(conn); /* done with the operation */

  /* if the transfer was completed in a paused state there can be buffered
     data left to write and then kill */
  if(data->state.tempwrite) {
    free(data->state.tempwrite);
    data->state.tempwrite = NULL;
  }

  /* if data->set.reuse_forbid is TRUE, it means the libcurl client has
     forced us to close this no matter what we think.

     if conn->bits.close is TRUE, it means that the connection should be
     closed in spite of all our efforts to be nice, due to protocol
     restrictions in our or the server's end

     if premature is TRUE, it means this connection was said to be DONE before
     the entire request operation is complete and thus we can't know in what
     state it is for re-using, so we're forced to close it. In a perfect world
     we can add code that keep track of if we really must close it here or not,
     but currently we have no such detail knowledge.

     connectindex == -1 here means that the connection has no spot in the
     connection cache and thus we must disconnect it here.
  */
  if(data->set.reuse_forbid || conn->bits.close || premature ||
     (-1 == conn->connectindex)) {
    CURLcode res2 = Curl_disconnect(conn, premature); /* close the connection */

    /* If we had an error already, make sure we return that one. But
       if we got a new error, return that. */
    if(!result && res2)
      result = res2;
  }
  else {
    ConnectionDone(conn); /* the connection is no longer in use */

    /* remember the most recently used connection */
    data->state.lastconnect = conn->connectindex;

    infof(data, "Connection #%ld to host %s left intact\n",
          conn->connectindex,
          conn->bits.httpproxy?conn->proxy.dispname:conn->host.dispname);
  }

  *connp = NULL; /* to make the caller of this function better detect that
                    this was either closed or handed over to the connection
                    cache here, and therefore cannot be used from this point on
                 */

  return result;
}

/*
 * do_init() inits the readwrite session. This is inited each time (in the DO
 * function before the protocol-specific DO functions are invoked) for a
 * transfer, sometimes multiple times on the same SessionHandle. Make sure
 * nothing in here depends on stuff that are setup dynamically for the
 * transfer.
 */

static CURLcode do_init(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  struct SingleRequest *k = &data->req;

  conn->bits.done = FALSE; /* Curl_done() is not called yet */
  conn->bits.do_more = FALSE; /* by default there's no curl_do_more() to use */
  data->state.expect100header = FALSE;

  if(data->set.opt_no_body)
    /* in HTTP lingo, no body means using the HEAD request... */
    data->set.httpreq = HTTPREQ_HEAD;
  else if(HTTPREQ_HEAD == data->set.httpreq)
    /* ... but if unset there really is no perfect method that is the
       "opposite" of HEAD but in reality most people probably think GET
       then. The important thing is that we can't let it remain HEAD if the
       opt_no_body is set FALSE since then we'll behave wrong when getting
       HTTP. */
    data->set.httpreq = HTTPREQ_GET;

  /* NB: the content encoding software depends on this initialization */
  Curl_easy_initHandleData(data);

  k->start = Curl_tvnow(); /* start time */
  k->now = k->start;   /* current time is now */
  k->header = TRUE; /* assume header */

  k->bytecount = 0;

  k->buf = data->state.buffer;
  k->uploadbuf = data->state.uploadbuffer;
  k->hbufp = data->state.headerbuff;
  k->ignorebody=FALSE;

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

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

  return CURLE_OK;
}

/*
 * do_complete is called when the DO actions are complete.
 *
 * We init chunking and trailer bits to their default values here immediately
 * before receiving any header data for the current request in the pipeline.
 */
static void do_complete(struct connectdata *conn)
{
  conn->data->req.chunk=FALSE;
  conn->data->req.maxfd = (conn->sockfd>conn->writesockfd?
                           conn->sockfd:conn->writesockfd)+1;
}

CURLcode Curl_do(struct connectdata **connp, bool *done)
{
  CURLcode result=CURLE_OK;
  struct connectdata *conn = *connp;
  struct SessionHandle *data = conn->data;

  /* setup and init stuff before DO starts, in preparing for the transfer */
  do_init(conn);

  if(conn->handler->do_it) {
    /* generic protocol-specific function pointer set in curl_connect() */
    result = conn->handler->do_it(conn, done);

    /* This was formerly done in transfer.c, but we better do it here */
    if((CURLE_SEND_ERROR == result) && conn->bits.reuse) {
        /*
         * If the connection is using an easy handle, call reconnect
         * to re-establish the connection.  Otherwise, let the multi logic
         * figure out how to re-establish the connection.
         */
        if(!data->multi) {
          result = Curl_reconnect_request(connp);

          if(result == CURLE_OK) {
            /* ... finally back to actually retry the DO phase */
            conn = *connp; /* re-assign conn since Curl_reconnect_request
                              creates a new connection */
            result = conn->handler->do_it(conn, done);
          }
        }
        else
          return result;
    }

    if((result == CURLE_OK) && *done)
      /* do_complete must be called after the protocol-specific DO function */
      do_complete(conn);
  }
  return result;
}

CURLcode Curl_do_more(struct connectdata *conn)
{
  CURLcode result=CURLE_OK;

  if(conn->handler->do_more)
    result = conn->handler->do_more(conn);

  if(result == CURLE_OK)
    /* do_complete must be called after the protocol-specific DO function */
    do_complete(conn);

  return result;
}

/* Called on connect, and if there's already a protocol-specific struct
   allocated for a different connection, this frees it that it can be setup
   properly later on. */
void Curl_reset_reqproto(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  if(data->state.proto.generic && data->state.current_conn != conn) {
    free(data->state.proto.generic);
    data->state.proto.generic = NULL;
  }
  data->state.current_conn = conn;
}