virtmodem.c

Modem通讯程序包

/*
 * $Id: virtmodem.c,v 1.7 1998/02/17 09:53:39 mdejonge Exp $
 *
 *   $Source: /home/mdejonge/CVS/projects/modem/tests/virtmodem.c,v $
 * $Revision: 1.7 $
 *    Author: Merijn de Jonge
 *     Email: [e-mail]
 *
 *
 *
 * This file is part of the modem communication package.
 * Copyright (C) 1996-1998  Merijn de Jonge
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif


#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <time.h>
#include <setjmp.h>
#include <sys/wait.h>
#include <stdlib.h>

#include <libport/libport.h>
#include <liberror/liberror.h>
#include <libtty/libtty.h>

/* Device name of virtual modem */
static char* virtModemDev;

/* Shell script executed to simulate a connection with a remote site */
#define VIRTMODEMSCRIPT  "./virtmodem.sh"

static pid_t   childPid = -1;
static jmp_buf saved_env;
static int terminated = 0;

typedef struct 
{
   int master;
   int slave;
   char slaveDevName[20];
} PTY;

PTY remote;
PTY local;

/* 
 * Open pseudo terminal and return PTY structure with file descriptors
 * and name of slave terminal
 */
PTY openPty()
{
   PTY pty;
   
   /* Open master device */
   pty.master = openPtyMaster( pty.slaveDevName );
   if( pty.master == -1 )
   {
      FAIL( "openPty" );
      exit( 1 );
   }
   
   /* And open slave pty */
   pty.slave = openPtySlave( pty.slaveDevName );
   if( pty.slave == -1 )
   {
      FAIL( "openPtySlave" );
      exit( 1 );
   }
   return pty;
}

void signalHandler( int sig )
{
   switch( sig )
   {
      case SIGCHLD:
         /* Exit when child has died */
         if( childPid == -1 )
            return;
         if( waitpid( childPid, NULL, 0 ) == -1 )
         {
            FAIL( "waitpid" );
            exit( 1 );
         }
         childPid = -1;
         /* Close pseudo terminal (That is, simulte a modem hangup */
         close( local.master );
         
         /* Indicate that we're done */
         terminated = 1;
         return;
      case SIGINT:
         exit( 0 );
   }
}

/* Fork and execute child program (VIRTMODEMSCRIPT) */
void startChild()
{
   childPid = fork();
   switch( childPid )
   {
      case -1:
         FAIL( "fork" );
         exit( 1 );
      case 0:
         /* stdin/stdout connected to remote pseudo terminal */
         dup2( remote.slave, STDIN_FILENO );
         dup2( remote.slave, STDOUT_FILENO );
         
         execl( VIRTMODEMSCRIPT, VIRTMODEMSCRIPT, NULL );
         FAIL1( "execl", VIRTMODEMSCRIPT ); 
         _exit( 1 );
   }
}


/* 
 * Exit routine, remove symbolic link to pseudo terminal and
 * kill child process if it still exists.
 */
void myExit()
{
   if( unlink( virtModemDev ) == -1 )
   {
      FAIL1( "unlink", virtModemDev );
   }

   if( childPid != -1 )
   {
      kill( childPid, SIGHUP );
   }
}

void copyData()
{   
   int    from;
   int    to;
   int    result;
   fd_set fds;
   int    bytes;
   char   buf[512];
   /* Copy data between pseudo terminals until exit */
   while( 1 )
   {
      FD_ZERO( &fds );
      FD_SET( remote.master, &fds );
      FD_SET( local.master, &fds );
      
      /* Use select to wait for any data */
      TEMP_FAILURE_RETRY( result,
                          select( FD_SETSIZE, &fds, NULL, NULL, NULL ) );
      if( result == -1 )
      {
         /* If we got an error because telnet session has terminated,
          * We long jump to start a new session
          */
         if( terminated == 1 )
            longjmp( saved_env, 1 );
         FAIL( "select" );
         exit( 1 );
      }
      
      /* Data from remote pseudo terminal */
      if( FD_ISSET( remote.master, &fds ) )
      {
         from = remote.master;
         to   = local.master;
      }
      else
      /* Data from local pseudo terminal */
      if( FD_ISSET( local.master, &fds ) )
      {
         from = local.master;
         to   = remote.master;
      }
      else
      { 
         error( "Unknown error during select" );
         exit( 1 );
      }
      
      /* read data from sending pseudo terminal... */
      TEMP_FAILURE_RETRY( bytes, read( from, buf, sizeof buf ) );
      if( bytes < 0 )
      {
         FAIL( "read" );
         exit( 1 );
      }
      if( bytes == 0 )
      {  
         /* Telnet session terminated; start a new session */
         if( childPid != -1 )
            kill( childPid, SIGHUP );
         /* long jump to restart telnet session */
         longjmp( saved_env, 1 );

      }
         
      /* ... and send it to the other pseudo terminal */
      TEMP_FAILURE_RETRY( bytes, write( to, buf, bytes ) );
      if( bytes < 0 )
      {
         FAIL( "write" );
         exit( 1 );
      }
      if( bytes == 0 )
      {  
         /* Telnet session terminated; start a new session */
            if( childPid != -1 )
               kill( childPid, SIGHUP );
         /* Long jump to restart telnet session */
         longjmp( saved_env, 1 );
      }
   }
}

int main( int argc, char* argv[] )
{
   struct sigaction act;
   int    result;

   if( argc != 2 )
   {
      error( "usage: %s dev", argv[0] );
      error( "   dev   name of virtual modem device (/tmp/virtmodem for example)" );
      
      exit( 1 );
   }
   virtModemDev = argv[1];
   
   /* Install handler for SIGINT and SIGCHLD*/
   sigemptyset( &act.sa_mask );
   act.sa_handler = signalHandler;
#ifdef SA_RESTART
   act.sa_flags   = SA_RESTART;
#endif            
   sigaction( SIGINT, &act, NULL );
   sigaction( SIGCHLD, &act, NULL );

   /* Cleanup required on termination */
   atexit( myExit );

   /* Open remote pseudo terminals */
   remote = openPty();
   
   /* Continuously spawn a telnet session and 
    * copy data between telnet session and modem server
    */
   while( 1 )
   {
      if( setjmp( saved_env ) == 1 )
      /* Non-local jump from copyData when telnet session terminates
       * We resart and spawn a  new session
       */
         continue;

      /* Open local pseudo terminal */
      local  = openPty();

      /* put local slave into raw terminal mode */
      ttySetRaw( local.slave );

      /* Remove symbolic link if it still exists */
      unlink( virtModemDev );

      /* Create symbolic link to opended local pseudo terminal device */
      result = symlink( local.slaveDevName, virtModemDev );
      if( result == -1 )
      {
         FAIL1( "symlink", virtModemDev );
         exit( 1 );
      }

      /* Fork child process */
      startChild();
      terminated = 0;
      
      /* Copy data between teh two pseudo terminals */
      copyData();
   }
   
}

/* EOF tests/virtmodem.c */