connect.c

用于嵌入式系统的TCP/IP协议栈

/***********************************************************************/
/*                                                                     */
/*   Module:  connect.c                                                */
/*   Release: 2001.3                                                   */
/*   Version: 2000.0                                                   */
/*   Purpose: connect() 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"
#include "../ip/ip.h"

/***********************************************************************/
/* Local Function Definitions                                          */
/***********************************************************************/

/***********************************************************************/
/*    tcp_conn: Actively establish TCP connection with peer            */
/*                                                                     */
/*       Input: sock = pointer to TCP socket                           */
/*                                                                     */
/*     Returns: 0 if no errors, else -1 with errno set to error code   */
/*                                                                     */
/***********************************************************************/
static int tcp_conn(SOCKET sock)
{
  int mss;

  /*-------------------------------------------------------------------*/
  /* Verify socket is not already connected.                           */
  /*-------------------------------------------------------------------*/
  if (sock->flags & SF_CONNECTED)
  {
    NetError(sock, EISCONN);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Check if a connection is in progress.                             */
  /*-------------------------------------------------------------------*/
  if (sock->flags & TCPF_SYN)
  {
    if ((sock->state == SS_SYNSENT) || (sock->state == SS_SYNRCVD))
    {
      NetError(sock, EINPROGRESS);
      return -1;
    }
    else
    {
      sock->flags &= ~TCPF_SYN;
      NetError(sock, sock->error);
      return -1;
    }
  }

  /*-------------------------------------------------------------------*/
  /* Allocate socket send buffer.                                      */
  /*-------------------------------------------------------------------*/
  if (sock->sbuf == NULL)
  {
    sock->sbuf = tcpGetBuf(sock->sb_size);
    if (sock->sbuf == NULL)
    {
      NetError(sock, ENOBUFS);
      return -1;
    }
  }

  /*-------------------------------------------------------------------*/
  /* Allocate socket receive buffer.                                   */
  /*-------------------------------------------------------------------*/
  if (sock->rbuf == NULL)
  {
    sock->rbuf = tcpGetBuf(sock->rb_size);
    if (sock->rbuf == NULL)
    {
      NetError(sock, ENOBUFS);
      return -1;
    }
  }

  /*-------------------------------------------------------------------*/
  /* If local port has not been specified, pick a unique port.         */
  /*-------------------------------------------------------------------*/
  if (sock->local.sin_port == 0)
  {
    sock->local.sin_port = TcpNextPort();
    if (sock->local.sin_port == 0)
    {
      NetError(sock, EMFILE);
      return -1;
    }
  }

  /*-------------------------------------------------------------------*/
  /* Else ensure socket's local and remote addresses are unique.       */
  /*-------------------------------------------------------------------*/
  else
  {
    SOCKET next;
    CircLink *link;

    for (link = TcpLruList.next_bck;; link = link->next_bck)
    {
      /*---------------------------------------------------------------*/
      /* Break if TCP socket list end is reached.                      */
      /*---------------------------------------------------------------*/
      if (link == &TcpLruList)
        break;

      /*---------------------------------------------------------------*/
      /* Error if a different socket has the same addresses.           */
      /*---------------------------------------------------------------*/
      next = (SOCKET)link;
      if ((sock->local.sin_port == next->local.sin_port) &&
          (sock->local.sin_addr.s_addr == next->local.sin_addr.s_addr) &&
          (sock->remote.sin_port == next->remote.sin_port) &&
          (sock->remote.sin_addr.s_addr == next->remote.sin_addr.s_addr))
      {
        if (next != sock)
        {
          NetError(sock, EADDRINUSE);
          return -1;
        }
      }
    }
  }

  /*-------------------------------------------------------------------*/
  /* Determine our maximum receive segment size.                       */
  /*-------------------------------------------------------------------*/
  mss = sock->route->ni->mtu - (IPMHLEN + TCPMHLEN);

  /*-------------------------------------------------------------------*/
  /* Initialization specific to active opens.                          */
  /*-------------------------------------------------------------------*/
  sock->snd_mss = sock->snd_window = sock->snd_cwnd = mss;
  if (mss > (sock->rb_size >> 1))
    sock->rcv_mss = sock->rb_size >> 1;
  else
    sock->rcv_mss = mss;
  sock->flags |= TCPF_SYN;
  sock->state = SS_SYNSENT;

  /*-------------------------------------------------------------------*/
  /* Reserve socket for TCP state machine and initiate SYN output.     */
  /*-------------------------------------------------------------------*/
  ++sock->reserve_cnt;
  ++Stats.TcpActiveOpens;
  TcpTryOut(sock);

  /*-------------------------------------------------------------------*/
  /* Start connect() timer to expire after timeout.                    */
  /*-------------------------------------------------------------------*/
  NetTimerStart(&sock->state_tmr, sock->connect_timeo);

  /*-------------------------------------------------------------------*/
  /* If non-blocking, return error.                                    */
  /*-------------------------------------------------------------------*/
  if (sock->flags & SF_NONBLKNG)
  {
    NetError(sock, EWOULDBLOCK);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Wait for event and check for timeout.                             */
  /*-------------------------------------------------------------------*/
  NetPendEvent(sock, SE_CLOSED | SE_OPENED, WAIT_FOREVER);
  if (sock->error)
  {
    NetError(sock, sock->error);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Return 0 for success.                                             */
  /*-------------------------------------------------------------------*/
  return 0;
}

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

/***********************************************************************/
/*     connect: Attach a remote address to a socket and, for stream    */
/*              sockets, actively establish connection with peer       */
/*                                                                     */
/*      Inputs: s = socket identifier                                  */
/*              a = pointer to remote address                          */
/*              addrlen = sizeof(struct sockaddr_in)                   */
/*                                                                     */
/*     Returns: 0 if no errors, else -1 with errno set to error code   */
/*                                                                     */
/***********************************************************************/
int connect(int s, const void *a, int addrlen)
{
  SOCKET sock = &Socks[s - 1];
  SockAddr *addr = (SockAddr *)a;
  Route *route;
  ui16 sin_port;
  ui32 s_addr;
  int rc = -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 a is not NULL and addrlen is the appropriate value.        */
  /*-------------------------------------------------------------------*/
  if (!a || (addrlen != sizeof(struct sockaddr_in)))
  {
    NetError(sock, EFAULT);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Verify the specified address family is AF_INET.                   */
  /*-------------------------------------------------------------------*/
  if (addr->sin_family != AF_INET)
  {
    NetError(sock, EPFNOSUPPORT);
    return -1;
  }

  /*-------------------------------------------------------------------*/
  /* Verify destination IP address and port number are not zero.       */
  /*-------------------------------------------------------------------*/
  if ((addr->sin_addr.s_addr == INADDR_ANY) || (addr->sin_port == 0))
  {
    NetError(sock, EDESTADDRREQ);
    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);

  /*-------------------------------------------------------------------*/
  /* Verify an acceptable route exists and cache it.                   */
  /*-------------------------------------------------------------------*/
  route = RtSearch(addr->sin_addr.s_addr);
  if ((route == NULL) ||
      ((sock->flags & SF_DONTROUTE) && (route->flags & RT_GATEWAY)))
  {
    sock->flags &= ~SF_CONNECTED;
    NetError(sock, ENETUNREACH);
    goto conn_exit;
  }
  sock->route = route;

  /*-------------------------------------------------------------------*/
  /* Save original local address and port, restored if UDP error.      */
  /*-------------------------------------------------------------------*/
  s_addr = sock->local.sin_addr.s_addr;
  sin_port = sock->local.sin_port;

  /*-------------------------------------------------------------------*/
  /* Assign local IP address if wild card IP address used.             */
  /*-------------------------------------------------------------------*/
  if (sock->local.sin_addr.s_addr == INADDR_ANY)
    sock->local.sin_addr.s_addr = route->ni->ip_addr;

  /*-------------------------------------------------------------------*/
  /* Assign specified remote port number and IP address to socket.     */
  /*-------------------------------------------------------------------*/
  sock->remote.sin_port = addr->sin_port;
  sock->remote.sin_addr = addr->sin_addr;

  /*-------------------------------------------------------------------*/
  /* UDP socket processing.                                            */
  /*-------------------------------------------------------------------*/
  if (sock->type == SOCK_DGRAM)
  {
    /*-----------------------------------------------------------------*/
    /* Verify destination IP address is an available address.          */
    /*-----------------------------------------------------------------*/
    if ((route->flags & RT_BRDCST) && !(sock->flags & SF_BROADCAST))
      NetError(sock, EACCES);

    /*-----------------------------------------------------------------*/
    /* Else perform UDP connection.                                    */
    /*-----------------------------------------------------------------*/
    else
      rc = UdpConnect(sock);

    /*-----------------------------------------------------------------*/
    /* UDP error clears connection and restores local addresses.       */
    /*-----------------------------------------------------------------*/
    if (rc)
    {
      sock->flags &= ~SF_CONNECTED;
      sock->local.sin_addr.s_addr = s_addr;
      sock->local.sin_port = sin_port;
    }
  }

  /*-------------------------------------------------------------------*/
  /* TCP socket processing.                                            */
  /*-------------------------------------------------------------------*/
  else
  {
    /*-----------------------------------------------------------------*/
    /* Verify destination IP address is an available address.          */
    /*-----------------------------------------------------------------*/
    if (route->flags & RT_BRDCST)
      NetError(sock, EADDRNOTAVAIL);

    /*-----------------------------------------------------------------*/
    /* Else perform active TCP connection.                             */
    /*-----------------------------------------------------------------*/
    else
      rc = tcp_conn(sock);
  }

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