Thu Jul 9 13:40:17 2009

Asterisk developer's documentation


app_dahdiras.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief Execute an ISDN RAS
00022  *
00023  * \author Mark Spencer <markster@digium.com>
00024  * 
00025  * \ingroup applications
00026  */
00027 
00028 /*** MODULEINFO
00029    <depend>dahdi</depend>
00030    <depend>working_fork</depend>
00031  ***/
00032 
00033 #include "asterisk.h"
00034 
00035 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 178306 $")
00036 
00037 #include <sys/ioctl.h>
00038 #include <sys/wait.h>
00039 #ifdef __linux__
00040 #include <sys/signal.h>
00041 #else
00042 #include <signal.h>
00043 #endif /* __linux__ */
00044 
00045 #include <dahdi/user.h>
00046 
00047 #include <fcntl.h>
00048 #ifdef HAVE_CAP
00049 #include <sys/capability.h>
00050 #endif /* HAVE_CAP */
00051 
00052 #include "asterisk/lock.h"
00053 #include "asterisk/file.h"
00054 #include "asterisk/channel.h"
00055 #include "asterisk/pbx.h"
00056 #include "asterisk/module.h"
00057 
00058 static char *app = "DAHDIRAS";
00059 
00060 static char *synopsis = "Executes DAHDI ISDN RAS application";
00061 
00062 static char *descrip =
00063 "  DAHDIRAS(args): Executes a RAS server using pppd on the given channel.\n"
00064 "The channel must be a clear channel (i.e. PRI source) and a DAHDI\n"
00065 "channel to be able to use this function (No modem emulation is included).\n"
00066 "Your pppd must be patched to be dahdi aware. Arguments should be\n"
00067 "separated by , characters.\n";
00068 
00069 
00070 #define PPP_MAX_ARGS 32
00071 #define PPP_EXEC  "/usr/sbin/pppd"
00072 
00073 static pid_t spawn_ras(struct ast_channel *chan, char *args)
00074 {
00075    pid_t pid;
00076    int x;   
00077    char *c;
00078 
00079    char *argv[PPP_MAX_ARGS];
00080    int argc = 0;
00081    char *stringp=NULL;
00082    sigset_t fullset, oldset;
00083 #ifdef HAVE_CAP
00084    cap_t cap;
00085 #endif
00086 
00087    sigfillset(&fullset);
00088    pthread_sigmask(SIG_BLOCK, &fullset, &oldset);
00089 
00090    /* Start by forking */
00091    pid = fork();
00092    if (pid) {
00093       pthread_sigmask(SIG_SETMASK, &oldset, NULL);
00094       return pid;
00095    }
00096 
00097 #ifdef HAVE_CAP
00098    cap = cap_from_text("cap_net_admin-eip");
00099 
00100    if (cap_set_proc(cap)) {
00101       /* Careful with order! Logging cannot happen after we close FDs */
00102       ast_log(LOG_WARNING, "Unable to remove capabilities.\n");
00103    }
00104    cap_free(cap);
00105 #endif
00106 
00107    /* Restore original signal handlers */
00108    for (x=0;x<NSIG;x++)
00109       signal(x, SIG_DFL);
00110 
00111    pthread_sigmask(SIG_UNBLOCK, &fullset, NULL);
00112 
00113    /* Execute RAS on File handles */
00114    dup2(chan->fds[0], STDIN_FILENO);
00115 
00116    /* Drop high priority */
00117    if (ast_opt_high_priority)
00118       ast_set_priority(0);
00119 
00120    /* Close other file descriptors */
00121    for (x=STDERR_FILENO + 1;x<1024;x++) 
00122       close(x);
00123 
00124    /* Reset all arguments */
00125    memset(argv, 0, sizeof(argv));
00126 
00127    /* First argument is executable, followed by standard
00128       arguments for dahdi PPP */
00129    argv[argc++] = PPP_EXEC;
00130    argv[argc++] = "nodetach";
00131 
00132    /* And all the other arguments */
00133    stringp=args;
00134    c = strsep(&stringp, ",");
00135    while(c && strlen(c) && (argc < (PPP_MAX_ARGS - 4))) {
00136       argv[argc++] = c;
00137       c = strsep(&stringp, ",");
00138    }
00139 
00140    argv[argc++] = "plugin";
00141    argv[argc++] = "dahdi.so";
00142    argv[argc++] = "stdin";
00143 
00144    /* Finally launch PPP */
00145    execv(PPP_EXEC, argv);
00146    fprintf(stderr, "Failed to exec PPPD!\n");
00147    exit(1);
00148 }
00149 
00150 static void run_ras(struct ast_channel *chan, char *args)
00151 {
00152    pid_t pid;
00153    int status;
00154    int res;
00155    int signalled = 0;
00156    struct dahdi_bufferinfo savebi;
00157    int x;
00158    
00159    res = ioctl(chan->fds[0], DAHDI_GET_BUFINFO, &savebi);
00160    if(res) {
00161       ast_log(LOG_WARNING, "Unable to check buffer policy on channel %s\n", chan->name);
00162       return;
00163    }
00164 
00165    pid = spawn_ras(chan, args);
00166    if (pid < 0) {
00167       ast_log(LOG_WARNING, "Failed to spawn RAS\n");
00168    } else {
00169       for (;;) {
00170          res = wait4(pid, &status, WNOHANG, NULL);
00171          if (!res) {
00172             /* Check for hangup */
00173             if (ast_check_hangup(chan) && !signalled) {
00174                ast_debug(1, "Channel '%s' hungup.  Signalling RAS at %d to die...\n", chan->name, pid);
00175                kill(pid, SIGTERM);
00176                signalled=1;
00177             }
00178             /* Try again */
00179             sleep(1);
00180             continue;
00181          }
00182          if (res < 0) {
00183             ast_log(LOG_WARNING, "wait4 returned %d: %s\n", res, strerror(errno));
00184          }
00185          if (WIFEXITED(status)) {
00186             ast_verb(3, "RAS on %s terminated with status %d\n", chan->name, WEXITSTATUS(status));
00187          } else if (WIFSIGNALED(status)) {
00188             ast_verb(3, "RAS on %s terminated with signal %d\n", 
00189                 chan->name, WTERMSIG(status));
00190          } else {
00191             ast_verb(3, "RAS on %s terminated weirdly.\n", chan->name);
00192          }
00193          /* Throw back into audio mode */
00194          x = 1;
00195          ioctl(chan->fds[0], DAHDI_AUDIOMODE, &x);
00196 
00197          /* Restore saved values */
00198          res = ioctl(chan->fds[0], DAHDI_SET_BUFINFO, &savebi);
00199          if (res < 0) {
00200             ast_log(LOG_WARNING, "Unable to set buffer policy on channel %s\n", chan->name);
00201          }
00202          break;
00203       }
00204    }
00205 }
00206 
00207 static int dahdiras_exec(struct ast_channel *chan, void *data)
00208 {
00209    int res=-1;
00210    char *args;
00211    struct dahdi_params dahdip;
00212 
00213    if (!data) 
00214       data = "";
00215 
00216    args = ast_strdupa(data);
00217    
00218    /* Answer the channel if it's not up */
00219    if (chan->_state != AST_STATE_UP)
00220       ast_answer(chan);
00221    if (strcasecmp(chan->tech->type, "DAHDI")) {
00222       /* If it's not a DAHDI channel, we're done.  Wait a couple of
00223          seconds and then hangup... */
00224       ast_verb(2, "Channel %s is not a DAHDI channel\n", chan->name);
00225       sleep(2);
00226    } else {
00227       memset(&dahdip, 0, sizeof(dahdip));
00228       if (ioctl(chan->fds[0], DAHDI_GET_PARAMS, &dahdip)) {
00229          ast_log(LOG_WARNING, "Unable to get DAHDI parameters\n");
00230       } else if (dahdip.sigtype != DAHDI_SIG_CLEAR) {
00231          ast_verb(2, "Channel %s is not a clear channel\n", chan->name);
00232       } else {
00233          /* Everything should be okay.  Run PPP. */
00234          ast_verb(3, "Starting RAS on %s\n", chan->name);
00235          /* Execute RAS */
00236          run_ras(chan, args);
00237       }
00238    }
00239    return res;
00240 }
00241 
00242 static int unload_module(void) 
00243 {
00244    return ast_unregister_application(app);
00245 }
00246 
00247 static int load_module(void)
00248 {
00249    return ((ast_register_application(app, dahdiras_exec, synopsis, descrip)) ? AST_MODULE_LOAD_FAILURE : AST_MODULE_LOAD_SUCCESS);
00250 }
00251 
00252 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "DAHDI ISDN Remote Access Server");
00253 

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