app_dahdiras.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Execute an ISDN RAS
 *
 * \author Mark Spencer <[email protected]>
 *
 * \ingroup applications
 */

/*** MODULEINFO
   <depend>dahdi</depend>
   <support_level>deprecated</support_level>
 ***/

#include "asterisk.h"

#include <sys/ioctl.h>
#include <sys/wait.h>
#include <signal.h>
#include <fcntl.h>

#include <dahdi/user.h>

#include "asterisk/lock.h"
#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/app.h"

/*** DOCUMENTATION
   <application name="DAHDIRAS" language="en_US">
      <synopsis>
         Executes DAHDI ISDN RAS application.
      </synopsis>
      <syntax>
         <parameter name="args" required="true">
            <para>A list of parameters to pass to the pppd daemon,
            separated by <literal>,</literal> characters.</para>
         </parameter>
      </syntax>
      <description>
         <para>Executes a RAS server using pppd on the given channel.
         The channel must be a clear channel (i.e. PRI source) and a DAHDI
         channel to be able to use this function (No modem emulation is included).</para>
         <para>Your pppd must be patched to be DAHDI aware.</para>
      </description>
   </application>

 ***/

static const char app[] = "DAHDIRAS";

#define PPP_MAX_ARGS 32
#define PPP_EXEC  "/usr/sbin/pppd"

static pid_t spawn_ras(struct ast_channel *chan, char *args)
{
   pid_t pid;
   char *c;

   char *argv[PPP_MAX_ARGS];
   int argc = 0;
   char *stringp=NULL;

   /* Start by forking */
   pid = ast_safe_fork(1);
   if (pid) {
      return pid;
   }

   /* Execute RAS on File handles */
   dup2(ast_channel_fd(chan, 0), STDIN_FILENO);

   /* Drop high priority */
   if (ast_opt_high_priority)
      ast_set_priority(0);

   /* Close other file descriptors */
   ast_close_fds_above_n(STDERR_FILENO);

   /* Reset all arguments */
   memset(argv, 0, sizeof(argv));

   /* First argument is executable, followed by standard
      arguments for DAHDI PPP */
   argv[argc++] = PPP_EXEC;
   argv[argc++] = "nodetach";

   /* And all the other arguments */
   stringp=args;
   c = strsep(&stringp, ",");
   while(c && strlen(c) && (argc < (PPP_MAX_ARGS - 4))) {
      argv[argc++] = c;
      c = strsep(&stringp, ",");
   }

   if (geteuid() == 0) {
      argv[argc++] = "plugin";
      argv[argc++] = "dahdi.so";
   }
   argv[argc++] = "stdin";

   /* Finally launch PPP */
   execv(PPP_EXEC, argv);
   fprintf(stderr, "Failed to exec PPPD!\n");
   exit(1);
}

static void run_ras(struct ast_channel *chan, char *args)
{
   pid_t pid;
   int status;
   int res;
   int signalled = 0;
   struct dahdi_bufferinfo savebi;
   int x;

   res = ioctl(ast_channel_fd(chan, 0), DAHDI_GET_BUFINFO, &savebi);
   if(res) {
      ast_log(LOG_WARNING, "Unable to check buffer policy on channel %s\n", ast_channel_name(chan));
      return;
   }

   pid = spawn_ras(chan, args);
   if (pid < 0) {
      ast_log(LOG_WARNING, "Failed to spawn RAS\n");
   } else {
      for (;;) {
         res = waitpid(pid, &status, WNOHANG);
         if (!res) {
            /* Check for hangup */
            if (ast_check_hangup(chan) && !signalled) {
               ast_debug(1, "Channel '%s' hungup.  Signalling RAS at %d to die...\n", ast_channel_name(chan), pid);
               kill(pid, SIGTERM);
               signalled=1;
            }
            /* Try again */
            sleep(1);
            continue;
         }
         if (res < 0) {
            ast_log(LOG_WARNING, "waitpid returned %d: %s\n", res, strerror(errno));
         }
         if (WIFEXITED(status)) {
            ast_verb(3, "RAS on %s terminated with status %d\n", ast_channel_name(chan), WEXITSTATUS(status));
         } else if (WIFSIGNALED(status)) {
            ast_verb(3, "RAS on %s terminated with signal %d\n",
                ast_channel_name(chan), WTERMSIG(status));
         } else {
            ast_verb(3, "RAS on %s terminated weirdly.\n", ast_channel_name(chan));
         }
         /* Throw back into audio mode */
         x = 1;
         ioctl(ast_channel_fd(chan, 0), DAHDI_AUDIOMODE, &x);

         /* Restore saved values */
         res = ioctl(ast_channel_fd(chan, 0), DAHDI_SET_BUFINFO, &savebi);
         if (res < 0) {
            ast_log(LOG_WARNING, "Unable to set buffer policy on channel %s\n", ast_channel_name(chan));
         }
         break;
      }
   }
   ast_safe_fork_cleanup();
}

static int dahdiras_exec(struct ast_channel *chan, const char *data)
{
   int res=-1;
   char *args;
   struct dahdi_params dahdip;

   if (!data)
      data = "";

   args = ast_strdupa(data);

   /* Answer the channel if it's not up */
   if (ast_channel_state(chan) != AST_STATE_UP)
      ast_answer(chan);
   if (strcasecmp(ast_channel_tech(chan)->type, "DAHDI")) {
      /* If it's not a DAHDI channel, we're done.  Wait a couple of
         seconds and then hangup... */
      ast_verb(2, "Channel %s is not a DAHDI channel\n", ast_channel_name(chan));
      sleep(2);
   } else {
      memset(&dahdip, 0, sizeof(dahdip));
      if (ioctl(ast_channel_fd(chan, 0), DAHDI_GET_PARAMS, &dahdip)) {
         ast_log(LOG_WARNING, "Unable to get DAHDI parameters\n");
      } else if (dahdip.sigtype != DAHDI_SIG_CLEAR) {
         ast_verb(2, "Channel %s is not a clear channel\n", ast_channel_name(chan));
      } else {
         /* Everything should be okay.  Run PPP. */
         ast_verb(3, "Starting RAS on %s\n", ast_channel_name(chan));
         /* Execute RAS */
         run_ras(chan, args);
      }
   }
   return res;
}

static int unload_module(void)
{
   return ast_unregister_application(app);
}

static int load_module(void)
{
   return ((ast_register_application_xml(app, dahdiras_exec)) ? AST_MODULE_LOAD_DECLINE : AST_MODULE_LOAD_SUCCESS);
}

AST_MODULE_INFO_STANDARD_DEPRECATED(ASTERISK_GPL_KEY, "DAHDI ISDN Remote Access Server");