Adding a new dialplan function AUDIOHOOK_INHERIT

This function is being added as a method to allow for
an audiohook to move to a new channel during a channel
masquerade. The most obvious use for such a facility is
for MixMonitor when a transfer is performed. Prior to
the addition of this functionality, if a channel 
running MixMonitor was transferred by another party, then
the recording would stop once the transfer had completed.
By using AUDIOHOOK_INHERIT, you can make MixMonitor 
continue recording the call even after the transfer
has completed.

It has also been determined that since this is seen
by most as a bug fix and is not an invasive change,
this functionality will also be backported to 1.4 and
merged into the 1.6.0 branches, even though they are
feature-frozen.

(closes issue #13538)
Reported by: mbit
Patches:
      13538.patch uploaded by putnopvut (license 60)
	  Tested by: putnopvut

Review: http://reviewboard.digium.com/r/102/



git-svn-id: http://svn.digium.com/svn/asterisk/trunk@166092 f38db490-d61c-443f-a65b-d21fe96a405b

5 files changed, 336 insertions, 2 deletions

diff --git a/CHANGES b/CHANGES
index 21c657bea..719a879f4 100644
--- a/CHANGES
+++ b/CHANGES
@@ -71,6 +71,8 @@ Dialplan Functions
  * Added LOCAL_PEEK, which I have no idea how to use, but Leif Madsen wanted it.
    Russell says it's, like, a scope resolution function for LOCAL variables.
    Totally.  Hopefully, that means more to you than it does to me.
+ * Added AUDIOHOOK_INHERIT. For information on its use, please see the output
+   of "core show function AUDIOHOOK_INHERIT" from the CLI
 
 Applications
 ------------
diff --git a/funcs/func_audiohookinherit.c b/funcs/func_audiohookinherit.c
new file mode 100644
index 000000000..5dd937d6f
--- /dev/null
+++ b/funcs/func_audiohookinherit.c
@@ -0,0 +1,293 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2008, Digium, Inc.
+ *
+ * Mark Michelson <mmichelson@digium.com>
+ *
+ * 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.
+ *
+ * Please follow coding guidelines
+ * http://svn.digium.com/view/asterisk/trunk/doc/CODING-GUIDELINES
+ */
+
+/*! \file
+ *
+ * \brief Audiohook inheritance function
+ *
+ * \author \verbatim Mark Michelson <mmichelson@digium.com> \endverbatim
+ *
+ * \ingroup functions
+ */
+
+#include "asterisk.h"
+#include "asterisk/datastore.h"
+#include "asterisk/channel.h"
+#include "asterisk/logger.h"
+#include "asterisk/audiohook.h"
+#include "asterisk/pbx.h"
+#include "asterisk/module.h"
+
+/*** DOCUMENTATION
+ 	<function name = "AUDIOHOOK_INHERIT" language="en_US">
+		<synopsis>
+			Set whether an audiohook may be inherited to another channel
+		</snopsis>
+		<syntax>
+			<parameter name="source" required="true">
+				<para>The built-in sources in Asterisk are</para>
+				<enumlist>
+					<enum name="MixMonitor" />
+					<enum name="Chanspy" />
+					<enum name="Volume" />
+					<enum name="Speex" />
+					<enum name="JACK_HOOK" />
+				</enumlist>
+				<para>Note that the names are not case-sensitive</para>
+			</parameter>
+		</syntax>
+		<description>
+			<para>By enabling audiohook inheritance on the channel, you are giving
+			permission for an audiohook to be inherited by a descendent channel.
+			Inheritance may be be disabled at any point as well.</para>
+
+			<para>Example scenario:</para>
+			<para>exten => 2000,1,MixMonitor(blah.wav)</para>
+			<para>exten => 2000,n,Set(AUDIOHOOK_INHERIT(MixMonitor)=yes)</para>
+			<para>exten => 2000,n,Dial(SIP/2000)</para>
+			<para>
+			</para>
+			<para>exten => 4000,1,Dial(SIP/4000)</para>
+			<para>
+			</para>
+			<para>exten => 5000,1,MixMonitor(blah2.wav)</para>
+			<para>exten => 5000,n,Dial(SIP/5000)</para>
+			<para>
+			</para>
+			<para>In this basic dialplan scenario, let's consider the following sample calls</para>
+			<para>Call 1: Caller dials 2000. The person who answers then executes an attended</para>
+			<para>        transfer to 4000.</para>
+			<para>Result: Since extension 2000 set MixMonitor to be inheritable, after the</para>
+			<para>        transfer to 4000 has completed, the call will continue to be recorded
+			to blah.wav</para>
+			<para>
+			</para>
+			<para>Call 2: Caller dials 5000. The person who answers then executes an attended</para>
+			<para>        transfer to 4000.</para>
+			<para>Result: Since extension 5000 did not set MixMonitor to be inheritable, the</para>
+			<para>        recording will stop once the call has been transferred to 4000.</para>
+		</description>
+	</function>
+ ***/
+
+struct inheritable_audiohook {
+	AST_LIST_ENTRY(inheritable_audiohook) list;
+	char source[1];
+};
+
+struct audiohook_inheritance_datastore {
+	AST_LIST_HEAD (, inheritable_audiohook) allowed_list;
+};
+
+static void audiohook_inheritance_fixup(void *data, struct ast_channel *old_chan, struct ast_channel *new_chan);
+static void audiohook_inheritance_destroy (void *data);
+static const struct ast_datastore_info audiohook_inheritance_info = {
+	.type = "audiohook inheritance",
+	.destroy = audiohook_inheritance_destroy,
+	.chan_fixup = audiohook_inheritance_fixup,
+};
+
+/*! \brief Move audiohooks as defined by previous calls to the AUDIOHOOK_INHERIT function
+ *
+ * Move allowed audiohooks from the old channel to the new channel.
+ *
+ * \param data The ast_datastore containing audiohook inheritance information that will be moved
+ * \param old_chan The "clone" channel from a masquerade. We are moving the audiohook in question off of this channel
+ * \param new_chan The "original" channel from a masquerade. We are moving the audiohook in question to this channel
+ * \return Void
+ */
+static void audiohook_inheritance_fixup(void *data, struct ast_channel *old_chan, struct ast_channel *new_chan)
+{
+	struct inheritable_audiohook *audiohook = NULL;
+	struct audiohook_inheritance_datastore *datastore = data;
+
+	ast_debug(2, "inheritance fixup occurring for channels %s(%p) and %s(%p)", old_chan->name, old_chan, new_chan->name, new_chan);
+
+	AST_LIST_TRAVERSE(&datastore->allowed_list, audiohook, list) {
+		ast_audiohook_move_by_source(old_chan, new_chan, audiohook->source);
+		ast_debug(3, "Moved audiohook %s from %s(%p) to %s(%p)\n",
+			audiohook->source, old_chan->name, old_chan, new_chan->name, new_chan);
+	}
+	return;
+}
+
+/*! \brief Destroy dynamically allocated data on an audiohook_inheritance_datastore
+ *
+ * \param data Pointer to the audiohook_inheritance_datastore in question.
+ * \return Void
+ */
+static void audiohook_inheritance_destroy(void *data)
+{
+	struct audiohook_inheritance_datastore *audiohook_inheritance_datastore = data;
+	struct inheritable_audiohook *inheritable_audiohook = NULL;
+
+	while ((inheritable_audiohook = AST_LIST_REMOVE_HEAD(&audiohook_inheritance_datastore->allowed_list, list))) {
+		ast_free(inheritable_audiohook);
+	}
+}
+
+/*! \brief create an audiohook_inheritance_datastore and attach it to a channel
+ *
+ * \param chan The channel to which we wish to attach the new datastore
+ * \return Returns the newly created audiohook_inheritance_datastore or NULL on error
+ */
+static struct audiohook_inheritance_datastore *setup_inheritance_datastore(struct ast_channel *chan)
+{
+	struct ast_datastore *datastore = NULL;
+	struct audiohook_inheritance_datastore *audiohook_inheritance_datastore = NULL;
+
+	if (!(datastore = ast_datastore_alloc(&audiohook_inheritance_info, NULL))) {
+		return NULL;
+	}
+
+	if (!(audiohook_inheritance_datastore = ast_calloc(1, sizeof(*audiohook_inheritance_datastore)))) {
+		ast_datastore_free(datastore);
+		return NULL;
+	}
+
+	datastore->data = audiohook_inheritance_datastore;
+	ast_channel_lock(chan);
+	ast_channel_datastore_add(chan, datastore);
+	ast_channel_unlock(chan);
+	return audiohook_inheritance_datastore;
+}
+
+/*! \brief Create a new inheritable_audiohook structure and add it to an audiohook_inheritance_datastore
+ *
+ * \param audiohook_inheritance_datastore The audiohook_inheritance_datastore we want to add the new inheritable_audiohook to
+ * \param source The audiohook source for the newly created inheritable_audiohook
+ * \retval 0 Success
+ * \retval non-zero Failure
+ */
+static int setup_inheritable_audiohook(struct audiohook_inheritance_datastore *audiohook_inheritance_datastore, const char *source)
+{
+	struct inheritable_audiohook *inheritable_audiohook = NULL;
+
+	inheritable_audiohook = ast_calloc(1, sizeof(*inheritable_audiohook) + strlen(source));
+
+	if (!inheritable_audiohook) {
+		return -1;
+	}
+
+	strcpy(inheritable_audiohook->source, source);
+	AST_LIST_INSERT_TAIL(&audiohook_inheritance_datastore->allowed_list, inheritable_audiohook, list);
+	ast_debug(3, "Set audiohook %s to be inheritable\n", source);
+	return 0;
+}
+
+/*! \brief Set the permissibility of inheritance for a particular audiohook source on a channel
+ *
+ * For details regarding what happens in the function, see the inline comments
+ *
+ * \param chan The channel we are operating on
+ * \param function The name of the dialplan function (AUDIOHOOK_INHERIT)
+ * \param data The audiohook source for which we are setting inheritance permissions
+ * \param value The value indicating the permission for audiohook inheritance
+ */
+static int func_inheritance_write(struct ast_channel *chan, const char *function, char *data, const char *value)
+{
+	int allow;
+	struct ast_datastore *datastore = NULL;
+	struct audiohook_inheritance_datastore *inheritance_datastore = NULL;
+	struct inheritable_audiohook *inheritable_audiohook;
+
+	/* Step 1: Get data from function call */
+	if (ast_strlen_zero(data)) {
+		ast_log(LOG_WARNING, "No argument provided to INHERITANCE function.\n");
+		return -1;
+	}
+
+	if (ast_strlen_zero(value)) {
+		ast_log(LOG_WARNING, "No value provided to INHERITANCE function.\n");
+		return -1;
+	}
+
+	allow = ast_true(value);
+
+	/* Step 2: retrieve or set up datastore */
+	ast_channel_lock(chan);
+	if (!(datastore = ast_channel_datastore_find(chan, &audiohook_inheritance_info, NULL))) {
+		ast_channel_unlock(chan);
+		/* In the case where we cannot find the datastore, we can take a few shortcuts */
+		if (!allow) {
+			ast_debug(1, "Audiohook %s is already set to not be inheritable on channel %s\n", data, chan->name);
+			return 0;
+		} else if (!(inheritance_datastore = setup_inheritance_datastore(chan))) {
+			ast_log(LOG_WARNING, "Unable to set up audiohook inheritance datastore on channel %s\n", chan->name);
+			return -1;
+		} else {
+			return setup_inheritable_audiohook(inheritance_datastore, data);
+		}
+	} else {
+		inheritance_datastore = datastore->data;
+	}
+	ast_channel_unlock(chan);
+
+	/* Step 3: Traverse the list to see if we're trying something redundant */
+
+	AST_LIST_TRAVERSE_SAFE_BEGIN(&inheritance_datastore->allowed_list, inheritable_audiohook, list) {
+		if (!strcasecmp(inheritable_audiohook->source, data)) {
+			if (allow) {
+				ast_debug(2, "Audiohook source %s is already set up to be inherited from channel %s\n", data, chan->name);
+				return 0;
+			} else {
+				ast_debug(2, "Removing inheritability of audiohook %s from channel %s\n", data, chan->name);
+				AST_LIST_REMOVE_CURRENT(list);
+				ast_free(inheritable_audiohook);
+				return 0;
+			}
+		}
+	}
+	AST_LIST_TRAVERSE_SAFE_END;
+
+	/* Step 4: There is no step 4 */
+
+	/* Step 5: This means we are addressing an audiohook source which we have not encountered yet for the channel. Create a new inheritable
+	 * audiohook structure if we're allowing inheritance, or just return if not
+	 */
+
+	if (allow) {
+		return setup_inheritable_audiohook(inheritance_datastore, data);
+	} else {
+		ast_debug(1, "Audiohook %s is already set to not be inheritable on channel %s\n", data, chan->name);
+		return 0;
+	}
+}
+
+static struct ast_custom_function inheritance_function = {
+	.name = "AUDIOHOOK_INHERIT",
+	.write = func_inheritance_write,
+};
+
+static int unload_module(void)
+{
+	return ast_custom_function_unregister(&inheritance_function);
+}
+
+static int load_module(void)
+{
+	if (ast_custom_function_register(&inheritance_function)) {
+		return AST_MODULE_LOAD_DECLINE;
+	} else {
+		return AST_MODULE_LOAD_SUCCESS;
+	}
+}
+AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Audiohook inheritance function");
diff --git a/include/asterisk/audiohook.h b/include/asterisk/audiohook.h
index cda2c2977..acda0a652 100644
--- a/include/asterisk/audiohook.h
+++ b/include/asterisk/audiohook.h
@@ -150,6 +150,21 @@ int ast_audiohook_detach(struct ast_audiohook *audiohook);
  */
 int ast_audiohook_detach_list(struct ast_audiohook_list *audiohook_list);
 
+/*! \brief Move an audiohook from one channel to a new one
+ *
+ * \todo Currently only the first audiohook of a specific source found will be moved.
+ * We should add the capability to move multiple audiohooks from a single source as well.
+ *
+ * \note It is required that both old_chan and new_chan are locked prior to calling
+ * this function. Besides needing to protect the data within the channels, not locking
+ * these channels can lead to a potential deadlock
+ *
+ * \param old_chan The source of the audiohook to move
+ * \param new_chan The destination to which we want the audiohook to move
+ * \param source The source of the audiohook we want to move
+ */
+void ast_audiohook_move_by_source(struct ast_channel *old_chan, struct ast_channel *new_chan, const char *source);
+
 /*! 
  * \brief Detach specified source audiohook from channel
  *
diff --git a/main/audiohook.c b/main/audiohook.c
index e493cfc71..b67625ff0 100644
--- a/main/audiohook.c
+++ b/main/audiohook.c
@@ -412,6 +412,11 @@ int ast_audiohook_detach_list(struct ast_audiohook_list *audiohook_list)
 	return 0;
 }
 
+/*! \brief find an audiohook based on its source
+ * \param audiohook_list The list of audiohooks to search in
+ * \param source The source of the audiohook we wish to find
+ * \return Return the corresponding audiohook or NULL if it cannot be found.
+ */
 static struct ast_audiohook *find_audiohook_by_source(struct ast_audiohook_list *audiohook_list, const char *source)
 {
 	struct ast_audiohook *audiohook = NULL;
@@ -434,6 +439,25 @@ static struct ast_audiohook *find_audiohook_by_source(struct ast_audiohook_list
 	return NULL;
 }
 
+void ast_audiohook_move_by_source (struct ast_channel *old_chan, struct ast_channel *new_chan, const char *source)
+{
+	struct ast_audiohook *audiohook = find_audiohook_by_source(old_chan->audiohooks, source);
+
+	if (!audiohook) {
+		return;
+	}
+	
+	/* By locking both channels and the audiohook, we can assure that
+	 * another thread will not have a chance to read the audiohook's status
+	 * as done, even though ast_audiohook_remove signals the trigger
+	 * condition
+	 */
+	ast_audiohook_lock(audiohook);
+	ast_audiohook_remove(old_chan, audiohook);
+	ast_audiohook_attach(new_chan, audiohook);
+	ast_audiohook_unlock(audiohook);
+}
+
 /*! \brief Detach specified source audiohook from channel
  * \param chan Channel to detach from
  * \param source Name of source to detach
diff --git a/main/channel.c b/main/channel.c
index 37535998b..ea1305411 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -4086,11 +4086,11 @@ int ast_do_masquerade(struct ast_channel *original)
 	/* Move data stores over */
 	if (AST_LIST_FIRST(&clonechan->datastores)) {
 		struct ast_datastore *ds;
-		AST_LIST_APPEND_LIST(&original->datastores, &clonechan->datastores, entry);
-		AST_LIST_TRAVERSE(&original->datastores, ds, entry) {
+		AST_LIST_TRAVERSE(&clonechan->datastores, ds, entry) {
 			if (ds->info->chan_fixup)
 				ds->info->chan_fixup(ds->data, clonechan, original);
 		}
+		AST_LIST_APPEND_LIST(&original->datastores, &clonechan->datastores, entry);
 	}
 
 	clone_variables(original, clonechan);