Wed Jan 27 20:02:04 2016

Asterisk developer's documentation


bridge_builtin_features.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2009, Digium, Inc.
00005  *
00006  * Joshua Colp <jcolp@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 Built in bridging features
00022  *
00023  * \author Joshua Colp <jcolp@digium.com>
00024  *
00025  * \ingroup bridges
00026  */
00027 
00028 /*** MODULEINFO
00029    <support_level>core</support_level>
00030  ***/
00031 
00032 #include "asterisk.h"
00033 
00034 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 361403 $")
00035 
00036 #include <stdio.h>
00037 #include <stdlib.h>
00038 #include <string.h>
00039 #include <sys/types.h>
00040 #include <sys/stat.h>
00041 
00042 #include "asterisk/module.h"
00043 #include "asterisk/channel.h"
00044 #include "asterisk/bridging.h"
00045 #include "asterisk/bridging_technology.h"
00046 #include "asterisk/frame.h"
00047 #include "asterisk/file.h"
00048 #include "asterisk/app.h"
00049 #include "asterisk/astobj2.h"
00050 
00051 /*! \brief Helper function that presents dialtone and grabs extension */
00052 static int grab_transfer(struct ast_channel *chan, char *exten, size_t exten_len, const char *context)
00053 {
00054    int res;
00055 
00056    /* Play the simple "transfer" prompt out and wait */
00057    res = ast_stream_and_wait(chan, "pbx-transfer", AST_DIGIT_ANY);
00058    ast_stopstream(chan);
00059 
00060    /* If the person hit a DTMF digit while the above played back stick it into the buffer */
00061    if (res) {
00062       exten[0] = (char)res;
00063    }
00064 
00065    /* Drop to dialtone so they can enter the extension they want to transfer to */
00066    res = ast_app_dtget(chan, context, exten, exten_len, 100, 1000);
00067 
00068    return res;
00069 }
00070 
00071 /*! \brief Helper function that creates an outgoing channel and returns it immediately */
00072 static struct ast_channel *dial_transfer(struct ast_channel *caller, const char *exten, const char *context)
00073 {
00074    char destination[AST_MAX_EXTENSION + AST_MAX_CONTEXT + 1];
00075    struct ast_channel *chan;
00076    int cause;
00077 
00078    /* Fill the variable with the extension and context we want to call */
00079    snprintf(destination, sizeof(destination), "%s@%s", exten, context);
00080 
00081    /* Now we request that chan_local prepare to call the destination */
00082    if (!(chan = ast_request("Local", caller->nativeformats, caller, destination, &cause))) {
00083       return NULL;
00084    }
00085 
00086    /* Before we actually dial out let's inherit appropriate information. */
00087    ast_channel_lock_both(caller, chan);
00088    ast_connected_line_copy_from_caller(&chan->connected, &caller->caller);
00089    ast_channel_inherit_variables(caller, chan);
00090    ast_channel_datastore_inherit(caller, chan);
00091    ast_channel_unlock(chan);
00092    ast_channel_unlock(caller);
00093 
00094    /* Since the above worked fine now we actually call it and return the channel */
00095    if (ast_call(chan, destination, 0)) {
00096       ast_hangup(chan);
00097       return NULL;
00098    }
00099 
00100    return chan;
00101 }
00102 
00103 /*! \brief Internal built in feature for blind transfers */
00104 static int feature_blind_transfer(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
00105 {
00106    char exten[AST_MAX_EXTENSION] = "";
00107    struct ast_channel *chan = NULL;
00108    struct ast_bridge_features_blind_transfer *blind_transfer = hook_pvt;
00109    const char *context = (blind_transfer && !ast_strlen_zero(blind_transfer->context) ? blind_transfer->context : bridge_channel->chan->context);
00110 
00111    /* Grab the extension to transfer to */
00112    if (!grab_transfer(bridge_channel->chan, exten, sizeof(exten), context)) {
00113       ast_stream_and_wait(bridge_channel->chan, "pbx-invalid", AST_DIGIT_ANY);
00114       ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
00115       return 0;
00116    }
00117 
00118    /* Get a channel that is the destination we wish to call */
00119    if (!(chan = dial_transfer(bridge_channel->chan, exten, context))) {
00120       ast_stream_and_wait(bridge_channel->chan, "beeperr", AST_DIGIT_ANY);
00121       ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
00122       return 0;
00123    }
00124 
00125    /* This is sort of the fun part. We impart the above channel onto the bridge, and have it take our place. */
00126    ast_bridge_impart(bridge, chan, bridge_channel->chan, NULL);
00127 
00128    return 0;
00129 }
00130 
00131 /*! \brief Attended transfer feature to turn it into a threeway call */
00132 static int attended_threeway_transfer(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
00133 {
00134    /* This is sort of abusing the depart state but in this instance it is only going to be handled in the below function so it is okay */
00135    ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_DEPART);
00136    return 0;
00137 }
00138 
00139 /*! \brief Attended transfer abort feature */
00140 static int attended_abort_transfer(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
00141 {
00142    struct ast_bridge_channel *called_bridge_channel = NULL;
00143 
00144    /* It is possible (albeit unlikely) that the bridge channels list may change, so we have to ensure we do all of our magic while locked */
00145    ao2_lock(bridge);
00146 
00147    if (AST_LIST_FIRST(&bridge->channels) != bridge_channel) {
00148       called_bridge_channel = AST_LIST_FIRST(&bridge->channels);
00149    } else {
00150       called_bridge_channel = AST_LIST_LAST(&bridge->channels);
00151    }
00152 
00153    /* Now we basically eject the other channel from the bridge. This will cause their thread to hang them up, and our own code to consider the transfer failed. */
00154    if (called_bridge_channel) {
00155       ast_bridge_change_state(called_bridge_channel, AST_BRIDGE_CHANNEL_STATE_HANGUP);
00156    }
00157 
00158    ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_END);
00159 
00160    ao2_unlock(bridge);
00161 
00162    return 0;
00163 }
00164 
00165 /*! \brief Internal built in feature for attended transfers */
00166 static int feature_attended_transfer(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
00167 {
00168    char exten[AST_MAX_EXTENSION] = "";
00169    struct ast_channel *chan = NULL;
00170    struct ast_bridge *attended_bridge = NULL;
00171    struct ast_bridge_features caller_features, called_features;
00172    enum ast_bridge_channel_state attended_bridge_result;
00173    struct ast_bridge_features_attended_transfer *attended_transfer = hook_pvt;
00174    const char *context = (attended_transfer && !ast_strlen_zero(attended_transfer->context) ? attended_transfer->context : bridge_channel->chan->context);
00175 
00176    /* Grab the extension to transfer to */
00177    if (!grab_transfer(bridge_channel->chan, exten, sizeof(exten), context)) {
00178       ast_stream_and_wait(bridge_channel->chan, "pbx-invalid", AST_DIGIT_ANY);
00179       ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
00180       return 0;
00181    }
00182 
00183    /* Get a channel that is the destination we wish to call */
00184    if (!(chan = dial_transfer(bridge_channel->chan, exten, context))) {
00185       ast_stream_and_wait(bridge_channel->chan, "beeperr", AST_DIGIT_ANY);
00186       ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
00187       return 0;
00188    }
00189 
00190    /* Create a bridge to use to talk to the person we are calling */
00191    if (!(attended_bridge = ast_bridge_new(AST_BRIDGE_CAPABILITY_1TO1MIX, 0))) {
00192       ast_hangup(chan);
00193       ast_stream_and_wait(bridge_channel->chan, "beeperr", AST_DIGIT_ANY);
00194       ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
00195       return 0;
00196    }
00197 
00198    /* Setup our called features structure so that if they hang up we immediately get thrown out of the bridge */
00199    ast_bridge_features_init(&called_features);
00200    ast_bridge_features_set_flag(&called_features, AST_BRIDGE_FLAG_DISSOLVE);
00201 
00202    /* This is how this is going down, we are imparting the channel we called above into this bridge first */
00203    ast_bridge_impart(attended_bridge, chan, NULL, &called_features);
00204 
00205    /* Before we join setup a features structure with the hangup option, just in case they want to use DTMF */
00206    ast_bridge_features_init(&caller_features);
00207    ast_bridge_features_enable(&caller_features, AST_BRIDGE_BUILTIN_HANGUP,
00208                (attended_transfer && !ast_strlen_zero(attended_transfer->complete) ? attended_transfer->complete : "*1"), NULL);
00209    ast_bridge_features_hook(&caller_features, (attended_transfer && !ast_strlen_zero(attended_transfer->threeway) ? attended_transfer->threeway : "*2"),
00210              attended_threeway_transfer, NULL);
00211    ast_bridge_features_hook(&caller_features, (attended_transfer && !ast_strlen_zero(attended_transfer->abort) ? attended_transfer->abort : "*3"),
00212              attended_abort_transfer, NULL);
00213 
00214    /* But for the caller we want to join the bridge in a blocking fashion so we don't spin around in this function doing nothing while waiting */
00215    attended_bridge_result = ast_bridge_join(attended_bridge, bridge_channel->chan, NULL, &caller_features);
00216 
00217    /* Since the above returned the caller features structure is of no more use */
00218    ast_bridge_features_cleanup(&caller_features);
00219 
00220    /* Drop the channel we are transferring to out of the above bridge since it has ended */
00221    if ((attended_bridge_result != AST_BRIDGE_CHANNEL_STATE_HANGUP) && !ast_bridge_depart(attended_bridge, chan)) {
00222       /* If the user wants to turn this into a threeway transfer then do so, otherwise they take our place */
00223       if (attended_bridge_result == AST_BRIDGE_CHANNEL_STATE_DEPART) {
00224          /* We want to impart them upon the bridge and just have us return to it as normal */
00225          ast_bridge_impart(bridge, chan, NULL, NULL);
00226       } else {
00227          ast_bridge_impart(bridge, chan, bridge_channel->chan, NULL);
00228       }
00229    } else {
00230       ast_stream_and_wait(bridge_channel->chan, "beeperr", AST_DIGIT_ANY);
00231       ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_WAIT);
00232    }
00233 
00234    /* Now that all channels are out of it we can destroy the bridge and the called features structure */
00235    ast_bridge_features_cleanup(&called_features);
00236    ast_bridge_destroy(attended_bridge);
00237 
00238    return 0;
00239 }
00240 
00241 /*! \brief Internal built in feature for hangup */
00242 static int feature_hangup(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
00243 {
00244    /* This is very simple, we basically change the state on the bridge channel to end and the core takes care of the rest */
00245    ast_bridge_change_state(bridge_channel, AST_BRIDGE_CHANNEL_STATE_END);
00246    return 0;
00247 }
00248 
00249 static int unload_module(void)
00250 {
00251    return 0;
00252 }
00253 
00254 static int load_module(void)
00255 {
00256    ast_bridge_features_register(AST_BRIDGE_BUILTIN_BLINDTRANSFER, feature_blind_transfer, NULL);
00257    ast_bridge_features_register(AST_BRIDGE_BUILTIN_ATTENDEDTRANSFER, feature_attended_transfer, NULL);
00258    ast_bridge_features_register(AST_BRIDGE_BUILTIN_HANGUP, feature_hangup, NULL);
00259 
00260    /* Bump up our reference count so we can't be unloaded */
00261    ast_module_ref(ast_module_info->self);
00262 
00263    return AST_MODULE_LOAD_SUCCESS;
00264 }
00265 
00266 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Built in bridging features");

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