Move more channel events to Stasis; move res_json.c to main/json.c.

This patch started out simply as fixing the bouncing tests introduced
in r382685, but required some other changes to give it a decent
implementation.

To fix the bouncing tests, the UserEvent and Newexten AMI events
needed to be refactored to dispatch via Stasis. Dispatching directly
to AMI resulted in those events sometimes getting ahead of the
associated Newchannel events, which would understandably confuse anyone.

I found that instead of creating a zillion different message types and
structures associated with them, it would be preferable to define a
message type that has a channel snapshot and a blob of structured data
with a small bit of additional information. The JSON object model
provides a very nice way of representing structured data, so I went
with that.

 * Move JSON support from res_json.c to main/json.c
   * Made libjansson-dev a required dependency
 * Added an ast_channel_blob message type, which has a channel
   snapshot and JSON blob of data.
 * Changed UserEvent and Newexten events so that they are dispatched
   via ast_channel_blob messages on the channel's topic.
 * Got rid of the ast_channel_varset message; used ast_channel_blob
   instead.
 * Extracted the manager functions converting Stasis channel events to
   AMI events into manager_channel.c.

(issue ASTERISK-21096)
Review: https://reviewboard.asterisk.org/r/2381/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@383579 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 409 insertions, 0 deletions

diff --git a/main/manager_channels.c b/main/manager_channels.c
new file mode 100644
index 000000000..802b34187
--- /dev/null
+++ b/main/manager_channels.c
@@ -0,0 +1,409 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2013, Digium, Inc.
+ *
+ * David M. Lee, II <dlee@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.
+ */
+
+/*! \file
+ *
+ * \brief The Asterisk Management Interface - AMI (channel event handling)
+ *
+ * \author David M. Lee, II <dlee@digium.com>
+ *
+ * AMI generated many per-channel and global-channel events by converting Stasis
+ * messages to AMI events. It makes sense to simply put them into a single file.
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/channel.h"
+#include "asterisk/manager.h"
+#include "asterisk/stasis_message_router.h"
+#include "asterisk/pbx.h"
+
+static struct stasis_message_router *channel_state_router;
+
+/*** DOCUMENTATION
+	<managerEvent language="en_US" name="Newchannel">
+		<managerEventInstance class="EVENT_FLAG_CALL">
+			<synopsis>Raised when a new channel is created.</synopsis>
+			<syntax>
+				<parameter name="Channel">
+				</parameter>
+				<parameter name="ChannelState">
+					<para>A numeric code for the channel's current state, related to ChannelStateDesc</para>
+				</parameter>
+				<parameter name="ChannelStateDesc">
+					<enumlist>
+						<enum name="Down"/>
+						<enum name="Rsrvd"/>
+						<enum name="OffHook"/>
+						<enum name="Dialing"/>
+						<enum name="Ring"/>
+						<enum name="Ringing"/>
+						<enum name="Up"/>
+						<enum name="Busy"/>
+						<enum name="Dialing Offhook"/>
+						<enum name="Pre-ring"/>
+						<enum name="Unknown"/>
+					</enumlist>
+				</parameter>
+				<parameter name="CallerIDNum">
+				</parameter>
+				<parameter name="CallerIDName">
+				</parameter>
+				<parameter name="ConnectedLineNum">
+				</parameter>
+				<parameter name="ConnectedLineName">
+				</parameter>
+				<parameter name="AccountCode">
+				</parameter>
+				<parameter name="Context">
+				</parameter>
+				<parameter name="Exten">
+				</parameter>
+				<parameter name="Priority">
+				</parameter>
+				<parameter name="Uniqueid">
+				</parameter>
+				<parameter name="Cause">
+					<para>A numeric cause code for why the channel was hung up.</para>
+				</parameter>
+				<parameter name="Cause-txt">
+					<para>A description of why the channel was hung up.</para>
+				</parameter>
+			</syntax>
+		</managerEventInstance>
+	</managerEvent>
+	<managerEvent language="en_US" name="Newstate">
+		<managerEventInstance class="EVENT_FLAG_CALL">
+			<synopsis>Raised when a channel's state changes.</synopsis>
+			<syntax>
+				<xi:include xpointer="xpointer(/docs/managerEvent[@name='Newchannel']/managerEventInstance/syntax/parameter)" />
+			</syntax>
+		</managerEventInstance>
+	</managerEvent>
+	<managerEvent language="en_US" name="Hangup">
+		<managerEventInstance class="EVENT_FLAG_CALL">
+			<synopsis>Raised when a channel is hung up.</synopsis>
+			<syntax>
+				<xi:include xpointer="xpointer(/docs/managerEvent[@name='Newchannel']/managerEventInstance/syntax/parameter)" />
+			</syntax>
+		</managerEventInstance>
+	</managerEvent>
+ ***/
+
+/*!
+ * \brief Generate the AMI message body from a channel snapshot
+ * \internal
+ *
+ * \param snapshot the channel snapshot for which to generate an AMI message
+ *                 body
+ *
+ * \retval NULL on error
+ * \retval ast_str* on success (must be ast_freed by caller)
+ */
+static struct ast_str *manager_build_channel_state_string(
+	const struct ast_channel_snapshot *snapshot)
+{
+	struct ast_str *out = ast_str_create(1024);
+	int res = 0;
+	if (!out) {
+		return NULL;
+	}
+	res = ast_str_set(&out, 0,
+		"Channel: %s\r\n"
+		"ChannelState: %d\r\n"
+		"ChannelStateDesc: %s\r\n"
+		"CallerIDNum: %s\r\n"
+		"CallerIDName: %s\r\n"
+		"ConnectedLineNum: %s\r\n"
+		"ConnectedLineName: %s\r\n"
+		"AccountCode: %s\r\n"
+		"Context: %s\r\n"
+		"Exten: %s\r\n"
+		"Priority: %d\r\n"
+		"Uniqueid: %s\r\n"
+		"Cause: %d\r\n"
+		"Cause-txt: %s\r\n",
+		snapshot->name,
+		snapshot->state,
+		ast_state2str(snapshot->state),
+		snapshot->caller_number,
+		snapshot->caller_name,
+		snapshot->connected_number,
+		snapshot->connected_name,
+		snapshot->accountcode,
+		snapshot->context,
+		snapshot->exten,
+		snapshot->priority,
+		snapshot->uniqueid,
+		snapshot->hangupcause,
+		ast_cause2str(snapshot->hangupcause));
+
+	if (!res) {
+		return NULL;
+	}
+
+	return out;
+}
+
+static inline int cep_has_changed(
+	const struct ast_channel_snapshot *old_snapshot,
+	const struct ast_channel_snapshot *new_snapshot)
+{
+	ast_assert(old_snapshot != NULL);
+	ast_assert(new_snapshot != NULL);
+	return old_snapshot->priority != new_snapshot->priority ||
+		strcmp(old_snapshot->context, new_snapshot->context) != 0 ||
+		strcmp(old_snapshot->exten, new_snapshot->exten) != 0;
+}
+
+static void channel_snapshot_update(void *data, struct stasis_subscription *sub,
+				    struct stasis_topic *topic,
+				    struct stasis_message *message)
+{
+	RAII_VAR(struct ast_str *, channel_event_string, NULL, ast_free);
+	struct stasis_cache_update *update = stasis_message_data(message);
+	struct ast_channel_snapshot *old_snapshot;
+	struct ast_channel_snapshot *new_snapshot;
+	int is_hungup, was_hungup;
+	char *manager_event = NULL;
+	int new_exten;
+
+	if (ast_channel_snapshot() != update->type) {
+		return;
+	}
+
+	old_snapshot = stasis_message_data(update->old_snapshot);
+	new_snapshot = stasis_message_data(update->new_snapshot);
+
+	if (!new_snapshot) {
+		/* Ignore cache clearing events; we'll see the hangup first */
+		return;
+	}
+
+	was_hungup = (old_snapshot && ast_test_flag(&old_snapshot->flags, AST_FLAG_ZOMBIE)) ? 1 : 0;
+	is_hungup = ast_test_flag(&new_snapshot->flags, AST_FLAG_ZOMBIE) ? 1 : 0;
+
+	if (!old_snapshot) {
+		manager_event = "Newchannel";
+	}
+
+	if (old_snapshot && old_snapshot->state != new_snapshot->state) {
+		manager_event = "Newstate";
+	}
+
+	if (!was_hungup && is_hungup) {
+		manager_event = "Hangup";
+	}
+
+	/* Detect Newexten transitions
+	 *  - if new snapshot has an application set AND
+	 *    - first snapshot OR
+	 *    - if the old snapshot has no application (first Newexten) OR
+	 *    - if the context/priority/exten changes
+	 */
+	new_exten = !ast_strlen_zero(new_snapshot->appl) && (
+		!old_snapshot ||
+		ast_strlen_zero(old_snapshot->appl) ||
+		cep_has_changed(old_snapshot, new_snapshot));
+
+	if (manager_event || new_exten) {
+		channel_event_string =
+			manager_build_channel_state_string(new_snapshot);
+	}
+
+	if (!channel_event_string) {
+		return;
+	}
+
+	/* Channel state change events */
+	if (manager_event) {
+		manager_event(EVENT_FLAG_CALL, manager_event, "%s",
+			      ast_str_buffer(channel_event_string));
+	}
+
+	if (new_exten) {
+		/* DEPRECATED: Extension field deprecated in 12; remove in 14 */
+		/*** DOCUMENTATION
+			<managerEventInstance>
+				<synopsis>Raised when a channel enters a new context, extension, priority.</synopsis>
+				<syntax>
+					<xi:include xpointer="xpointer(/docs/managerEvent[@name='Newchannel']/managerEventInstance/syntax/parameter)" />
+					<parameter name="Extension">
+						<para>Deprecated in 12, but kept for
+						backward compatability. Please use
+						'Exten' instead.</para>
+					</parameter>
+					<parameter name="Application">
+						<para>The application about to be executed.</para>
+					</parameter>
+					<parameter name="AppData">
+						<para>The data to be passed to the application.</para>
+					</parameter>
+				</syntax>
+			</managerEventInstance>
+		***/
+		manager_event(EVENT_FLAG_DIALPLAN, "Newexten",
+			      "%s"
+			      "Extension: %s\r\n"
+			      "Application: %s\r\n"
+			      "AppData: %s\r\n",
+			      ast_str_buffer(channel_event_string),
+			      new_snapshot->exten,
+			      new_snapshot->appl,
+			      new_snapshot->data);
+	}
+}
+
+static void channel_varset(struct ast_channel_blob *obj)
+{
+	RAII_VAR(struct ast_str *, channel_event_string, NULL, ast_free);
+	const char *variable = ast_json_string_get(ast_json_object_get(obj->blob, "variable"));
+	const char *value = ast_json_string_get(ast_json_object_get(obj->blob, "value"));
+
+	if (obj->snapshot) {
+		channel_event_string = manager_build_channel_state_string(obj->snapshot);
+	} else {
+		channel_event_string = ast_str_create(35);
+		ast_str_set(&channel_event_string, 0,
+			    "Channel: none\r\n"
+			    "Uniqueid: none\r\n");
+	}
+
+	if (!channel_event_string) {
+		return;
+	}
+
+	/*** DOCUMENTATION
+		<managerEventInstance>
+			<synopsis>Raised when a variable is set to a particular value.</synopsis>
+			<syntax>
+				<xi:include xpointer="xpointer(/docs/managerEvent[@name='Newchannel']/managerEventInstance/syntax/parameter)" />
+				<parameter name="Variable">
+					<para>The variable being set.</para>
+				</parameter>
+				<parameter name="Value">
+					<para>The new value of the variable.</para>
+				</parameter>
+			</syntax>
+		</managerEventInstance>
+	***/
+	manager_event(EVENT_FLAG_DIALPLAN, "VarSet",
+		      "%s"
+		      "Variable: %s\r\n"
+		      "Value: %s\r\n",
+		      ast_str_buffer(channel_event_string),
+		      variable, value);
+}
+
+static void channel_userevent(struct ast_channel_blob *obj)
+{
+	RAII_VAR(struct ast_str *, channel_event_string, NULL, ast_free);
+	const char *eventname;
+	const char *body;
+
+	eventname = ast_json_string_get(ast_json_object_get(obj->blob, "eventname"));
+	body = ast_json_string_get(ast_json_object_get(obj->blob, "body"));
+	channel_event_string = manager_build_channel_state_string(obj->snapshot);
+
+	if (!channel_event_string) {
+		return;
+	}
+
+	/*** DOCUMENTATION
+		<managerEventInstance>
+			<synopsis>A user defined event raised from the dialplan.</synopsis>
+			<syntax>
+				<xi:include xpointer="xpointer(/docs/managerEvent[@name='Newchannel']/managerEventInstance/syntax/parameter)" />
+				<parameter name="UserEvent">
+					<para>The event name, as specified in the dialplan.</para>
+				</parameter>
+			</syntax>
+			<see-also>
+				<ref type="application">UserEvent</ref>
+			</see-also>
+		</managerEventInstance>
+	***/
+	manager_event(EVENT_FLAG_USER, "UserEvent",
+		      "%s"
+		      "UserEvent: %s\r\n"
+		      "%s",
+		      ast_str_buffer(channel_event_string), eventname, body);
+}
+
+/*!
+ * \brief Callback processing messages on the channel topic.
+ */
+static void channel_blob_cb(void *data, struct stasis_subscription *sub,
+			    struct stasis_topic *topic,
+			    struct stasis_message *message)
+{
+	struct ast_channel_blob *obj = stasis_message_data(message);
+
+	if (strcmp("varset", ast_channel_blob_type(obj)) == 0) {
+		channel_varset(obj);
+	} else if (strcmp("userevent", ast_channel_blob_type(obj)) == 0) {
+		channel_userevent(obj);
+	}
+}
+
+static void manager_channels_shutdown(void)
+{
+	stasis_message_router_unsubscribe(channel_state_router);
+	channel_state_router = NULL;
+}
+
+int manager_channels_init(void)
+{
+	int ret = 0;
+
+	if (channel_state_router) {
+		/* Already initialized */
+		return 0;
+	}
+
+	ast_register_atexit(manager_channels_shutdown);
+
+	channel_state_router = stasis_message_router_create(
+		stasis_caching_get_topic(ast_channel_topic_all_cached()));
+
+	if (!channel_state_router) {
+		return -1;
+	}
+
+	ret |= stasis_message_router_add(channel_state_router,
+					 stasis_cache_update(),
+					 channel_snapshot_update,
+					 NULL);
+
+	ret |= stasis_message_router_add(channel_state_router,
+					 ast_channel_blob(),
+					 channel_blob_cb,
+					 NULL);
+
+	/* If somehow we failed to add any routes, just shut down the whole
+	 * things and fail it.
+	 */
+	if (ret) {
+		manager_channels_shutdown();
+		return -1;
+	}
+
+	return 0;
+}