connect.c

   *************************************************************/
  long timeout_ms;

  DEBUGASSERT(sockconn);
  *connected = FALSE; /* default to not connected */

  /* get the timeout left */
  timeout_ms = Curl_timeleft(data, &before, TRUE);

  if(timeout_ms < 0) {
    /* a precaution, no need to continue if time already is up */
    failf(data, "Connection time-out");
    return CURLE_OPERATION_TIMEDOUT;
  }

  /* Max time for each address */
  conn->num_addr = Curl_num_addresses(remotehost->addr);
  conn->timeoutms_per_addr = timeout_ms / conn->num_addr;

  ai = remotehost->addr;

  /* Below is the loop that attempts to connect to all IP-addresses we
   * know for the given host. One by one until one IP succeeds.
   */

  /*
   * Connecting with a Curl_addrinfo chain
   */
  for(curr_addr = ai, aliasindex=0; curr_addr;
      curr_addr = curr_addr->ai_next, aliasindex++) {

    /* start connecting to the IP curr_addr points to */
    CURLcode res =
      singleipconnect(conn, curr_addr,
                      /* don't hang when doing multi */
                      (data->state.used_interface == Curl_if_multi)?0:
                      conn->timeoutms_per_addr, &sockfd, connected);

    if(res)
      return res;

    if(sockfd != CURL_SOCKET_BAD)
      break;

    /* get a new timeout for next attempt */
    after = Curl_tvnow();
    timeout_ms -= Curl_tvdiff(after, before);
    if(timeout_ms < 0) {
      failf(data, "connect() timed out!");
      return CURLE_OPERATION_TIMEDOUT;
    }
    before = after;
  }  /* end of connect-to-each-address loop */

  *sockconn = sockfd;    /* the socket descriptor we've connected */

  if(sockfd == CURL_SOCKET_BAD) {
    /* no good connect was made */
    failf(data, "couldn't connect to host");
    return CURLE_COULDNT_CONNECT;
  }

  /* leave the socket in non-blocking mode */

  /* store the address we use */
  if(addr)
    *addr = curr_addr;

  data->info.numconnects++; /* to track the number of connections made */

  return CURLE_OK;
}

/*
 * Used to extract socket and connectdata struct for the most recent
 * transfer on the given SessionHandle.
 *
 * The returned socket will be CURL_SOCKET_BAD in case of failure!
 */
curl_socket_t Curl_getconnectinfo(struct SessionHandle *data,
                                  struct connectdata **connp)
{
  curl_socket_t sockfd;

  DEBUGASSERT(data);

  if((data->state.lastconnect != -1) &&
     (data->state.connc->connects[data->state.lastconnect] != NULL)) {
    struct connectdata *c =
      data->state.connc->connects[data->state.lastconnect];
    if(connp)
      /* only store this if the caller cares for it */
      *connp = c;
    sockfd = c->sock[FIRSTSOCKET];
    /* we have a socket connected, let's determine if the server shut down */
    /* determine if ssl */
    if(c->ssl[FIRSTSOCKET].use) {
      /* use the SSL context */
      if(!Curl_ssl_check_cxn(c))
        return CURL_SOCKET_BAD;   /* FIN received */
    }
/* Minix 3.1 doesn't support any flags on recv; just assume socket is OK */
#ifdef MSG_PEEK
    else {
      /* use the socket */
      char buf;
      if(recv((RECV_TYPE_ARG1)c->sock[FIRSTSOCKET], (RECV_TYPE_ARG2)&buf,
              (RECV_TYPE_ARG3)1, (RECV_TYPE_ARG4)MSG_PEEK) == 0) {
        return CURL_SOCKET_BAD;   /* FIN received */
      }
    }
#endif
  }
  else
    return CURL_SOCKET_BAD;

  return sockfd;
}

/*
 * Close a socket.
 *
 * 'conn' can be NULL, beware!
 */
int Curl_closesocket(struct connectdata *conn,
                     curl_socket_t sock)
{
  if(conn && conn->fclosesocket) {
    if((sock == conn->sock[SECONDARYSOCKET]) &&
       conn->sock_accepted[SECONDARYSOCKET])
      /* if this socket matches the second socket, and that was created with
         accept, then we MUST NOT call the callback but clear the accepted
         status */
      conn->sock_accepted[SECONDARYSOCKET] = FALSE;
    else
      return conn->fclosesocket(conn->closesocket_client, sock);
  }
  return sclose(sock);
}

/*
 * Create a socket based on info from 'conn' and 'ai'.
 *
 * 'addr' should be a pointer to the correct struct to get data back, or NULL.
 * 'sockfd' must be a pointer to a socket descriptor.
 *
 * If the open socket callback is set, used that!
 *
 */
CURLcode Curl_socket(struct connectdata *conn,
                     const Curl_addrinfo *ai,
                     struct Curl_sockaddr_ex *addr,
                     curl_socket_t *sockfd)
{
  struct SessionHandle *data = conn->data;
  struct Curl_sockaddr_ex dummy;

  if(!addr)
    /* if the caller doesn't want info back, use a local temp copy */
    addr = &dummy;

  /*
   * The Curl_sockaddr_ex structure is basically libcurl's external API
   * curl_sockaddr structure with enough space available to directly hold
   * any protocol-specific address structures. The variable declared here
   * will be used to pass / receive data to/from the fopensocket callback
   * if this has been set, before that, it is initialized from parameters.
   */

  addr->family = ai->ai_family;
  addr->socktype = conn->socktype;
  addr->protocol = conn->socktype==SOCK_DGRAM?IPPROTO_UDP:ai->ai_protocol;
  addr->addrlen = ai->ai_addrlen;

  if(addr->addrlen > sizeof(struct Curl_sockaddr_storage))
     addr->addrlen = sizeof(struct Curl_sockaddr_storage);
  memcpy(&addr->sa_addr, ai->ai_addr, addr->addrlen);

  if(data->set.fopensocket)
   /*
    * If the opensocket callback is set, all the destination address
    * information is passed to the callback. Depending on this information the
    * callback may opt to abort the connection, this is indicated returning
    * CURL_SOCKET_BAD; otherwise it will return a not-connected socket. When
    * the callback returns a valid socket the destination address information
    * might have been changed and this 'new' address will actually be used
    * here to connect.
    */
    *sockfd = data->set.fopensocket(data->set.opensocket_client,
                                    CURLSOCKTYPE_IPCXN,
                                    (struct curl_sockaddr *)addr);
  else
    /* opensocket callback not set, so simply create the socket now */
    *sockfd = socket(addr->family, addr->socktype, addr->protocol);

  if(*sockfd == CURL_SOCKET_BAD)
    /* no socket, no connection */
    return CURLE_FAILED_INIT;

#if defined(ENABLE_IPV6) && defined(HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID)
  if(conn->scope && (addr->family == AF_INET6)) {
    struct sockaddr_in6 * const sa6 = (void *)&addr->sa_addr;
    sa6->sin6_scope_id = conn->scope;
  }
#endif

  return CURLE_OK;

}