Wed Aug 18 22:33:52 2010

Asterisk developer's documentation


func_audiohookinherit.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2008, Digium, Inc.
00005  *
00006  * Mark Michelson <mmichelson@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  * Please follow coding guidelines
00019  * http://svn.digium.com/view/asterisk/trunk/doc/CODING-GUIDELINES
00020  */
00021 
00022 /*! \file
00023  *
00024  * \brief Audiohook inheritance function
00025  *
00026  * \author Mark Michelson <mmichelson@digium.com>
00027  *
00028  * \ingroup functions
00029  */
00030 
00031 #include "asterisk.h"
00032 #include "asterisk/datastore.h"
00033 #include "asterisk/channel.h"
00034 #include "asterisk/logger.h"
00035 #include "asterisk/audiohook.h"
00036 #include "asterisk/pbx.h"
00037 #include "asterisk/module.h"
00038 
00039 struct inheritable_audiohook {
00040    AST_LIST_ENTRY(inheritable_audiohook) list;
00041    char source[1];
00042 };
00043 
00044 struct audiohook_inheritance_datastore {
00045    AST_LIST_HEAD (, inheritable_audiohook) allowed_list;
00046 };
00047 
00048 static void audiohook_inheritance_fixup(void *data, struct ast_channel *old_chan, struct ast_channel *new_chan);
00049 static void audiohook_inheritance_destroy (void *data);
00050 static const struct ast_datastore_info audiohook_inheritance_info = {
00051    .type = "audiohook inheritance",
00052    .destroy = audiohook_inheritance_destroy,
00053    .chan_fixup = audiohook_inheritance_fixup,
00054 };
00055 
00056 /*! \brief Move audiohooks as defined by previous calls to the AUDIOHOOK_INHERIT function
00057  *
00058  * Move allowed audiohooks from the old channel to the new channel.
00059  *
00060  * \param data The ast_datastore containing audiohook inheritance information that will be moved
00061  * \param old_chan The "clone" channel from a masquerade. We are moving the audiohook in question off of this channel
00062  * \param new_chan The "original" channel from a masquerade. We are moving the audiohook in question to this channel
00063  * \return Void
00064  */
00065 static void audiohook_inheritance_fixup(void *data, struct ast_channel *old_chan, struct ast_channel *new_chan)
00066 {
00067    struct inheritable_audiohook *audiohook = NULL;
00068    struct audiohook_inheritance_datastore *datastore = data;
00069 
00070    ast_debug(2, "inheritance fixup occurring for channels %s(%p) and %s(%p)", old_chan->name, old_chan, new_chan->name, new_chan);
00071 
00072    AST_LIST_TRAVERSE(&datastore->allowed_list, audiohook, list) {
00073       ast_audiohook_move_by_source(old_chan, new_chan, audiohook->source);
00074       ast_debug(3, "Moved audiohook %s from %s(%p) to %s(%p)\n",
00075          audiohook->source, old_chan->name, old_chan, new_chan->name, new_chan);
00076    }
00077    return;
00078 }
00079 
00080 /*! \brief Destroy dynamically allocated data on an audiohook_inheritance_datastore
00081  *
00082  * \param data Pointer to the audiohook_inheritance_datastore in question.
00083  * \return Void
00084  */
00085 static void audiohook_inheritance_destroy(void *data)
00086 {
00087    struct audiohook_inheritance_datastore *audiohook_inheritance_datastore = data;
00088    struct inheritable_audiohook *inheritable_audiohook = NULL;
00089 
00090    while ((inheritable_audiohook = AST_LIST_REMOVE_HEAD(&audiohook_inheritance_datastore->allowed_list, list))) {
00091       ast_free(inheritable_audiohook);
00092    }
00093 
00094    ast_free(audiohook_inheritance_datastore);
00095 }
00096 
00097 /*! \brief create an audiohook_inheritance_datastore and attach it to a channel
00098  *
00099  * \param chan The channel to which we wish to attach the new datastore
00100  * \return Returns the newly created audiohook_inheritance_datastore or NULL on error
00101  */
00102 static struct audiohook_inheritance_datastore *setup_inheritance_datastore(struct ast_channel *chan)
00103 {
00104    struct ast_datastore *datastore = NULL;
00105    struct audiohook_inheritance_datastore *audiohook_inheritance_datastore = NULL;
00106 
00107    if (!(datastore = ast_datastore_alloc(&audiohook_inheritance_info, NULL))) {
00108       return NULL;
00109    }
00110 
00111    if (!(audiohook_inheritance_datastore = ast_calloc(1, sizeof(*audiohook_inheritance_datastore)))) {
00112       ast_datastore_free(datastore);
00113       return NULL;
00114    }
00115 
00116    datastore->data = audiohook_inheritance_datastore;
00117    ast_channel_lock(chan);
00118    ast_channel_datastore_add(chan, datastore);
00119    ast_channel_unlock(chan);
00120    return audiohook_inheritance_datastore;
00121 }
00122 
00123 /*! \brief Create a new inheritable_audiohook structure and add it to an audiohook_inheritance_datastore
00124  *
00125  * \param audiohook_inheritance_datastore The audiohook_inheritance_datastore we want to add the new inheritable_audiohook to
00126  * \param source The audiohook source for the newly created inheritable_audiohook
00127  * \retval 0 Success
00128  * \retval non-zero Failure
00129  */
00130 static int setup_inheritable_audiohook(struct audiohook_inheritance_datastore *audiohook_inheritance_datastore, const char *source)
00131 {
00132    struct inheritable_audiohook *inheritable_audiohook = NULL;
00133 
00134    inheritable_audiohook = ast_calloc(1, sizeof(*inheritable_audiohook) + strlen(source));
00135 
00136    if (!inheritable_audiohook) {
00137       return -1;
00138    }
00139 
00140    strcpy(inheritable_audiohook->source, source);
00141    AST_LIST_INSERT_TAIL(&audiohook_inheritance_datastore->allowed_list, inheritable_audiohook, list);
00142    ast_debug(3, "Set audiohook %s to be inheritable\n", source);
00143    return 0;
00144 }
00145 
00146 /*! \brief Set the permissibility of inheritance for a particular audiohook source on a channel
00147  *
00148  * For details regarding what happens in the function, see the inline comments
00149  *
00150  * \param chan The channel we are operating on
00151  * \param function The name of the dialplan function (AUDIOHOOK_INHERIT)
00152  * \param data The audiohook source for which we are setting inheritance permissions
00153  * \param value The value indicating the permission for audiohook inheritance
00154  */
00155 static int func_inheritance_write(struct ast_channel *chan, const char *function, char *data, const char *value)
00156 {
00157    int allow;
00158    struct ast_datastore *datastore = NULL;
00159    struct audiohook_inheritance_datastore *inheritance_datastore = NULL;
00160    struct inheritable_audiohook *inheritable_audiohook;
00161 
00162    /* Step 1: Get data from function call */
00163    if (ast_strlen_zero(data)) {
00164       ast_log(LOG_WARNING, "No argument provided to INHERITANCE function.\n");
00165       return -1;
00166    }
00167 
00168    if (ast_strlen_zero(value)) {
00169       ast_log(LOG_WARNING, "No value provided to INHERITANCE function.\n");
00170       return -1;
00171    }
00172 
00173    allow = ast_true(value);
00174 
00175    /* Step 2: retrieve or set up datastore */
00176    ast_channel_lock(chan);
00177    if (!(datastore = ast_channel_datastore_find(chan, &audiohook_inheritance_info, NULL))) {
00178       ast_channel_unlock(chan);
00179       /* In the case where we cannot find the datastore, we can take a few shortcuts */
00180       if (!allow) {
00181          ast_debug(1, "Audiohook %s is already set to not be inheritable on channel %s\n", data, chan->name);
00182          return 0;
00183       } else if (!(inheritance_datastore = setup_inheritance_datastore(chan))) {
00184          ast_log(LOG_WARNING, "Unable to set up audiohook inheritance datastore on channel %s\n", chan->name);
00185          return -1;
00186       } else {
00187          return setup_inheritable_audiohook(inheritance_datastore, data);
00188       }
00189    } else {
00190       inheritance_datastore = datastore->data;
00191    }
00192    ast_channel_unlock(chan);
00193 
00194    /* Step 3: Traverse the list to see if we're trying something redundant */
00195 
00196    AST_LIST_TRAVERSE_SAFE_BEGIN(&inheritance_datastore->allowed_list, inheritable_audiohook, list) {
00197       if (!strcasecmp(inheritable_audiohook->source, data)) {
00198          if (allow) {
00199             ast_debug(2, "Audiohook source %s is already set up to be inherited from channel %s\n", data, chan->name);
00200             return 0;
00201          } else {
00202             ast_debug(2, "Removing inheritability of audiohook %s from channel %s\n", data, chan->name);
00203             AST_LIST_REMOVE_CURRENT(list);
00204             ast_free(inheritable_audiohook);
00205             return 0;
00206          }
00207       }
00208    }
00209    AST_LIST_TRAVERSE_SAFE_END;
00210 
00211    /* Step 4: There is no step 4 */
00212 
00213    /* Step 5: This means we are addressing an audiohook source which we have not encountered yet for the channel. Create a new inheritable
00214     * audiohook structure if we're allowing inheritance, or just return if not
00215     */
00216 
00217    if (allow) {
00218       return setup_inheritable_audiohook(inheritance_datastore, data);
00219    } else {
00220       ast_debug(1, "Audiohook %s is already set to not be inheritable on channel %s\n", data, chan->name);
00221       return 0;
00222    }
00223 }
00224 
00225 static struct ast_custom_function inheritance_function = {
00226    .name = "AUDIOHOOK_INHERIT",
00227    .synopsis = "Set whether an audiohook may be inherited to another channel",
00228    .syntax = "AUDIOHOOK_INHERIT(source)",
00229    .desc =
00230       "By enabling audiohook inheritance on the channel, you are giving\n"
00231       "permission for an audiohook to be inherited by a descendent channel.\n"
00232       "Inheritance may be be disabled at any point as well.\n"
00233       "\n"
00234       "  Example scenario:\n"
00235       "  exten => 2000,1,MixMonitor(blah.wav)\n"
00236       "  exten => 2000,n,Set(AUDIOHOOK_INHERIT(MixMonitor)=yes)\n"
00237       "  exten => 2000,n,Dial(SIP/2000)\n"
00238       "\n"
00239       "  exten => 4000,1,Dial(SIP/4000)\n"
00240       "\n"
00241       "  exten => 5000,1,MixMonitor(blah2.wav)\n"
00242       "  exten => 5000,n,Dial(SIP/5000)\n"
00243       "\n"
00244       "  In this basic dialplan scenario, let's consider the following sample calls\n"
00245       "  Call 1: Caller dials 2000. The person who answers then executes an attended\n"
00246       "          transfer to 4000.\n"
00247       "  Result: Since extension 2000 set MixMonitor to be inheritable, after the\n"
00248       "          transfer to 400 has completed, the call will continue to be recorded\n"
00249       "           to blah.wav\n"
00250       "\n"
00251       "  Call 2: Caller dials 5000. The person who answers then executes an attended\n"
00252       "          transfer to 4000.\n"
00253       "  Result: Since extension 5000 did not set MixMonitor to be inheritable, the\n"
00254       "          recording will stop once the call has been transferred to 4000.\n",
00255    .write = func_inheritance_write,
00256 };
00257 
00258 static int unload_module(void)
00259 {
00260    return ast_custom_function_unregister(&inheritance_function);
00261 }
00262 
00263 static int load_module(void)
00264 {
00265    if (ast_custom_function_register(&inheritance_function)) {
00266       return AST_MODULE_LOAD_DECLINE;
00267    } else {
00268       return AST_MODULE_LOAD_SUCCESS;
00269    }
00270 }
00271 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Audiohook inheritance function");

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