connect.c

 * pointer with the connected socket.
 */

CURLcode Curl_connecthost(struct connectdata *conn,  /* context */
                          const struct Curl_dns_entry *remotehost,
                          curl_socket_t *sockconn,   /* the connected socket */
                          Curl_addrinfo **addr,      /* the one we used */
                          bool *connected)           /* really connected? */
{
  struct SessionHandle *data = conn->data;
  curl_socket_t sockfd = CURL_SOCKET_BAD;
  int aliasindex;
  int num_addr;
  Curl_addrinfo *ai;
  Curl_addrinfo *curr_addr;

  struct timeval after;
  struct timeval before = Curl_tvnow();

  /*************************************************************
   * Figure out what maximum time we have left
   *************************************************************/
  long timeout_ms;
  long timeout_per_addr;

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

  /* get the timeout left */
  timeout_ms = Curl_timeleft(conn, &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 */
  num_addr = Curl_num_addresses(remotehost->addr);
  timeout_per_addr = timeout_ms / 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.
   */

  if(data->state.used_interface == Curl_if_multi)
    /* don't hang when doing multi */
    timeout_per_addr = 0;

  /*
   * 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, timeout_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;
  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;
}