shutdown.c

用于嵌入式系统的TCP/IP协议栈

/***********************************************************************/
/*                                                                     */
/*   Module:  shutdown.c                                               */
/*   Release: 2001.3                                                   */
/*   Version: 99.0                                                     */
/*   Purpose: shutdown() 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"
#include "../tcp/tcp.h"

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

/***********************************************************************/
/*    shutdown: Shutdown a socket connection                           */
/*                                                                     */
/*      Inputs: s = socket identifier                                  */
/*              how = how connection is shutdown: SHUT_RD, SHUT_WR, or */
/*                    SHUT_RDWR (0, 1, or 2)                           */
/*                                                                     */
/***********************************************************************/
int shutdown(int s, int how)
{
  int rc = 0;
  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;
  }

  /*-------------------------------------------------------------------*/
  /* Check that the value of how is valid.                             */
  /*-------------------------------------------------------------------*/
  if ((how < SHUT_RD) || (how > SHUT_RDWR))
  {
    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);

  /*-------------------------------------------------------------------*/
  /* If TCP socket, verify that it is connected.                       */
  /*-------------------------------------------------------------------*/
  if ((sock->type == SOCK_STREAM) && !(sock->flags & SF_CONNECTED))
  {
    rc = -1;
    NetError(sock, ENOTCONN);
    goto shtdn_exit;
  }

  /*-------------------------------------------------------------------*/
  /* Set shutdown flags and post shutdown event to socket.             */
  /*-------------------------------------------------------------------*/
  if (how == SHUT_RD)
  {
    sock->flags |= SF_RCV_SHUT;
    NetPostEvent(sock, SE_RCV_SHUT);
  }
  else if (how == SHUT_WR)
  {
    sock->flags |= SF_SND_SHUT;
    NetPostEvent(sock, SE_SND_SHUT);
  }
  else
  {
    sock->flags |= SF_RCV_SHUT | SF_SND_SHUT;
    NetPostEvent(sock, SE_RCV_SHUT | SE_SND_SHUT);
  }

  /*-------------------------------------------------------------------*/
  /* Check if shutting down further sends on connected TCP socket.     */
  /*-------------------------------------------------------------------*/
  if (how && (sock->type == SOCK_STREAM))
  {
    /*-----------------------------------------------------------------*/
    /* Send FIN if it hasn't alread been sent.                         */
    /*-----------------------------------------------------------------*/
    if ((sock->state == SS_CLOSEWAIT) || (sock->state == SS_ESTABLISHED))
    {
      /*---------------------------------------------------------------*/
      /* Mark that FIN is needed and record its sequence number.       */
      /*---------------------------------------------------------------*/
      sock->flags |= SF_SNDFIN;
      sock->fin_seq = sock->snt_una + sock->sb_count;

      /*---------------------------------------------------------------*/
      /* Update state to either FIN_WAIT_1 or LAST_ACK.                */
      /*---------------------------------------------------------------*/
      if (sock->state == SS_CLOSEWAIT)
        sock->state = SS_LASTACK;
      else /* state == ESTABLISHED */
        sock->state = SS_FINWAIT1;

      /*---------------------------------------------------------------*/
      /* Start output state machine.                                   */
      /*---------------------------------------------------------------*/
      TcpTryOut(sock);
    }
  }

  /*-------------------------------------------------------------------*/
  /* Check if shutting down further receives.                          */
  /*-------------------------------------------------------------------*/
  if (sock->flags & SF_RCV_SHUT)
  {
    /*-----------------------------------------------------------------*/
    /* If TCP socket, free receive buffers and OOS queue.              */
    /*-----------------------------------------------------------------*/
    if (sock->type == SOCK_STREAM)
      TcpStrip(sock, FREE_RBUF);

    /*-----------------------------------------------------------------*/
    /* Else free UDP socket's datagram queue.                          */
    /*-----------------------------------------------------------------*/
    else
    {
      while (sock->rq_head)
      {
        NetBuf *buf = sock->rq_head;

        sock->rq_head = buf->next;
        tcpRetBuf(&buf);
      }
    }
  }

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