listen.c

用于嵌入式系统的TCP/IP协议栈

/***********************************************************************/
/*                                                                     */
/*   Module:  listen.c                                                 */
/*   Release: 2001.3                                                   */
/*   Version: 99.0                                                     */
/*   Purpose: listen() implementation                                  */
/*                                                                     */
/*---------------------------------------------------------------------*/
/*                                                                     */
/*               Copyright 1999, Blunk Microsystems                    */
/*                      ALL RIGHTS RESERVED                            */
/*                                                                     */
/*   Licensees have the non-exclusive right to use, modify, or extract */
/*   this computer program for software development at a single site.  */
/*   This program may be resold or disseminated in executable format   */
/*   only. The source code may not be redistributed or resold.         */
/*                                                                     */
/***********************************************************************/
#include "../tcp_ipp.h"

/***********************************************************************/
/* Symbol Definitions                                                  */
/***********************************************************************/
#define MAX_BACKLOG     5

/***********************************************************************/
/* Global Function Definitions                                         */
/***********************************************************************/

/***********************************************************************/
/*      listen: Prepare socket to wait for active TCP connection       */
/*                                                                     */
/*      Inputs: s = socket identifier                                  */
/*              backlog = maximum listen queue size                    */
/*                                                                     */
/*     Returns: 0 if no errors, else -1 with errno set to error code   */
/*                                                                     */
/***********************************************************************/
int listen(int s, int backlog)
{
  int rc;
  SOCKET sock = &Socks[s - 1];

#if OS_PARM_CHECK
  /*-------------------------------------------------------------------*/
  /* Verify protocol has been initialized.                             */
  /*-------------------------------------------------------------------*/
  if (!Net.Initialized)
  {
    NetError(NULL, ENETDOWN);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Check for valid socket ID.                                        */
  /*-------------------------------------------------------------------*/
  if (InvalidHandle(s))
  {
    NetError(NULL, ENOTSOCK);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Verify that backlog is in allowed range.                          */
  /*-------------------------------------------------------------------*/
  if ((backlog < 1) || (backlog > MAX_BACKLOG))
  {
    NetError(sock, EINVAL);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Verify that socket type is TCP.                                   */
  /*-------------------------------------------------------------------*/
  if (sock->type != SOCK_STREAM)
  {
    NetError(sock, EOPNOTSUPP);
    return -1;
  }
#endif

  /*-------------------------------------------------------------------*/
  /* Gain exclusive socket API access and stack internals access.      */
  /*-------------------------------------------------------------------*/
  if (semPend(sock->api_access, WAIT_FOREVER))
  {
    NetError(NULL, ENOTSOCK);
    return -1;
  }
  semPend(Net.IntSem, WAIT_FOREVER);

  /*-------------------------------------------------------------------*/
  /* Check if socket has not been bound.                               */
  /*-------------------------------------------------------------------*/
  if (sock->local.sin_port == 0)
  {
    NetError(sock, EINVAL);
    rc = -1;
  }

  /*-------------------------------------------------------------------*/
  /* Else check if socket is unconnected.                              */
  /*-------------------------------------------------------------------*/
  else if (sock->flags & SF_CONNECTED)
  {
    NetError(sock, EISCONN);
    rc = -1;
  }

  /*-------------------------------------------------------------------*/
  /* Else set socket state to LISTEN and initialize backlog.           */
  /*-------------------------------------------------------------------*/
  else
  {
    sock->state = SS_LISTEN;
    sock->lis_backlog = backlog;
    rc = 0;
  }

  /*-------------------------------------------------------------------*/
  /* Release exclusive API and internals access. Return status code.   */
  /*-------------------------------------------------------------------*/
  semPost(sock->api_access);
  semPost(Net.IntSem);
  return rc;
}