accept.c

用于嵌入式系统的TCP/IP协议栈

/***********************************************************************/
/*                                                                     */
/*   Module:  accept.c                                                 */
/*   Release: 2001.3                                                   */
/*   Version: 99.0                                                     */
/*   Purpose: accept() 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"

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

/***********************************************************************/
/*      accept: Accept incoming TCP connection requests                */
/*                                                                     */
/*      Inputs: s = socket identifier                                  */
/*              *addrlen = sizeof(struct sockaddr_in)                  */
/*                                                                     */
/*      Output: If addr not NULL, *addr = address of connected peer    */
/*                                                                     */
/*     Returns: New socket ID or else -1 with errno set to error code  */
/*                                                                     */
/***********************************************************************/
int accept(int s, void *addr, int *addrlen)
{
  SOCKET new, 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 addrlen and *addrlen are appropriate values.          */
  /*-------------------------------------------------------------------*/
  if (addr)
  {
    if ((addrlen == NULL) || (*addrlen != sizeof(struct sockaddr_in)))
    {
      NetError(sock, EFAULT);
      return -1;
    }
  }

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

  /*-------------------------------------------------------------------*/
  /* Verify that socket state is listen.                               */
  /*-------------------------------------------------------------------*/
  if (sock->state != SS_LISTEN)
  {
    NetError(sock, EINVAL);
    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 there is no pending connection request.                  */
  /*-------------------------------------------------------------------*/
  if (sock->lq_head == NULL)
  {
    /*-----------------------------------------------------------------*/
    /* Return error if socket is non-blocking.                         */
    /*-----------------------------------------------------------------*/
    if (sock->flags & SF_NONBLKNG)
    {
      NetError(sock, EWOULDBLOCK);
      goto accept_error;
    }

    /*-----------------------------------------------------------------*/
    /* Wait until a connection arrives. Return error if closed.        */
    /*-----------------------------------------------------------------*/
    NetPendEvent(sock, SE_ACCEPTED, WAIT_FOREVER);
    if (sock->lq_head == NULL)
    {
      NetError(sock, sock->error);
      goto accept_error;
    }
  }

  /*-------------------------------------------------------------------*/
  /* Extract new socket from listen queue.                             */
  /*-------------------------------------------------------------------*/
  new = sock->lq_head;
  sock->lq_head = sock->lq_head->lq_next;
  --sock->q_count;

  /*-------------------------------------------------------------------*/
  /* If requested, output connection's remote SockAddr.                */
  /*-------------------------------------------------------------------*/
  if (addr)
    *(struct sockaddr_in *)addr = new->remote;

  /*-------------------------------------------------------------------*/
  /* Release exclusive API and internals access and return new socket. */
  /*-------------------------------------------------------------------*/
  semPost(sock->api_access);
  semPost(Net.IntSem);
  return (new - &Socks[0]) + 1;

accept_error:
  semPost(sock->api_access);
  semPost(Net.IntSem);
  return -1;
}