Stasis application WebSocket support

This is the API that binds the Stasis dialplan application to external
Stasis applications. It also adds the beginnings of WebSocket
application support.

This module registers a dialplan function named Stasis, which is used
to put a channel into the named Stasis app. As a channel enters and
leaves the Stasis diaplan application, the Stasis app receives a
'stasis-start' and 'stasis-end' events.

Stasis apps register themselves using the stasis_app_register and
stasis_app_unregister functions. Messages are sent to an application
using stasis_app_send.

Finally, Stasis apps control channels through the use of the
stasis_app_control object, and the family of stasis_app_control_*
functions.

Other changes along for the ride are:
 * An ast_frame_dtor function that's RAII_VAR safe
 * Some common JSON encoders for name/number, timeval, and
   context/extension/priority

Review: https://reviewboard.asterisk.org/r/2361/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@384879 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 555 insertions, 0 deletions

diff --git a/apps/app_stasis.c b/apps/app_stasis.c
new file mode 100644
index 000000000..769c91521
--- /dev/null
+++ b/apps/app_stasis.c
@@ -0,0 +1,555 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2012 - 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 Stasis dialplan application.
+ *
+ * \author David M. Lee, II <dlee@digium.com>
+ */
+
+/*** MODULEINFO
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/app.h"
+#include "asterisk/app_stasis.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/channel.h"
+#include "asterisk/module.h"
+#include "asterisk/stasis.h"
+#include "asterisk/strings.h"
+
+/*** DOCUMENTATION
+	<application name="Stasis" language="en_US">
+		<synopsis>Invoke an external Stasis application.</synopsis>
+		<syntax>
+			<parameter name="app_name" required="true">
+				<para>Name of the application to invoke.</para>
+			</parameter>
+			<parameter name="args">
+				<para>Optional comma-delimited arguments for the application invocation.</para>
+			</parameter>
+		</syntax>
+		<description>
+			<para>
+				Invoke a Stasis application.
+			</para>
+		</description>
+	</application>
+ ***/
+
+/*! \brief Maximum number of arguments for the Stasis dialplan application */
+#define MAX_ARGS 128
+
+/*! \brief Dialplan application name */
+static const char *stasis = "Stasis";
+
+/*!
+ * \brief Number of buckets for the Stasis application hash table.  Remember to
+ * keep it a prime number!
+ */
+#define APPS_NUM_BUCKETS 127
+
+/*!
+ * \brief Number of buckets for the Stasis application hash table.  Remember to
+ * keep it a prime number!
+ */
+#define CONTROLS_NUM_BUCKETS 127
+
+/*!
+ * \brief Stasis application container. Please call apps_registry() instead of
+ * directly accessing.
+ */
+struct ao2_container *__apps_registry;
+
+struct ao2_container *__app_controls;
+
+/*! Ref-counting accessor for the stasis applications container */
+static struct ao2_container *apps_registry(void)
+{
+	ao2_ref(__apps_registry, +1);
+	return __apps_registry;
+}
+
+static struct ao2_container *app_controls(void)
+{
+	ao2_ref(__app_controls, +1);
+	return __app_controls;
+}
+
+struct app {
+	/*! Callback function for this application. */
+	stasis_app_cb handler;
+	/*! Opaque data to hand to callback function. */
+	void *data;
+	/*! Name of the Stasis application */
+	char name[];
+};
+
+static void app_dtor(void *obj)
+{
+	struct app *app = obj;
+
+	ao2_cleanup(app->data);
+	app->data = NULL;
+}
+
+/*! Constructor for \ref app. */
+static struct app *app_create(const char *name, stasis_app_cb handler, void *data)
+{
+	struct app *app;
+	size_t size;
+
+	ast_assert(name != NULL);
+	ast_assert(handler != NULL);
+
+	size = sizeof(*app) + strlen(name) + 1;
+	app = ao2_alloc_options(size, app_dtor, AO2_ALLOC_OPT_LOCK_MUTEX);
+
+	if (!app) {
+		return NULL;
+	}
+
+	strncpy(app->name, name, size - sizeof(*app));
+	app->handler = handler;
+	ao2_ref(data, +1);
+	app->data = data;
+
+	return app;
+}
+
+/*! AO2 hash function for \ref app */
+static int app_hash(const void *obj, const int flags)
+{
+	const struct app *app = obj;
+	const char *name = flags & OBJ_KEY ? obj : app->name;
+
+	return ast_str_hash(name);
+}
+
+/*! AO2 comparison function for \ref app */
+static int app_compare(void *lhs, void *rhs, int flags)
+{
+	const struct app *lhs_app = lhs;
+	const struct app *rhs_app = rhs;
+	const char *rhs_name = flags & OBJ_KEY ? rhs : rhs_app->name;
+
+	if (strcmp(lhs_app->name, rhs_name) == 0) {
+		return CMP_MATCH | CMP_STOP;
+	} else {
+		return 0;
+	}
+}
+
+/*!
+ * \brief Send a message to the given application.
+ * \param app App to send the message to.
+ * \param message Message to send.
+ */
+static void app_send(struct app *app, struct ast_json *message)
+{
+	app->handler(app->data, app->name, message);
+}
+
+struct stasis_app_control {
+	/*!
+	 * When set, /c app_stasis should exit and continue in the dialplan.
+	 */
+	int continue_to_dialplan:1;
+	/*! Uniqueid of the associated channel */
+	char channel_uniqueid[];
+};
+
+static struct stasis_app_control *control_create(const char *uniqueid)
+{
+	struct stasis_app_control *control;
+	size_t size;
+
+	size = sizeof(*control) + strlen(uniqueid) + 1;
+	control = ao2_alloc(size, NULL);
+	if (!control) {
+		return NULL;
+	}
+
+	strncpy(control->channel_uniqueid, uniqueid, size - sizeof(*control));
+
+	return control;
+}
+
+struct stasis_app_control *stasis_app_control_find_by_channel(
+	const struct ast_channel *chan)
+{
+	RAII_VAR(struct ao2_container *, controls, NULL, ao2_cleanup);
+	if (chan == NULL) {
+		return NULL;
+	}
+
+	controls = app_controls();
+	return ao2_find(controls, ast_channel_uniqueid(chan), OBJ_KEY);
+}
+
+/*!
+ * \brief Test the \c continue_to_dialplan bit for the given \a app.
+ *
+ * The bit is also reset for the next call.
+ *
+ * \param app Application to check the \c continue_to_dialplan bit.
+ * \return Zero to remain in \c Stasis
+ * \return Non-zero to continue in the dialplan
+ */
+static int control_continue_test_and_reset(struct stasis_app_control *control)
+{
+        int r;
+        SCOPED_AO2LOCK(lock, control);
+
+        r = control->continue_to_dialplan;
+        control->continue_to_dialplan = 0;
+        return r;
+}
+
+void stasis_app_control_continue(struct stasis_app_control *control)
+{
+	SCOPED_AO2LOCK(lock, control);
+	control->continue_to_dialplan = 1;
+}
+
+static struct ast_json *app_event_create(
+	const char *event_name,
+	const struct ast_channel_snapshot *snapshot,
+	const struct ast_json *extra_info)
+{
+	RAII_VAR(struct ast_json *, message, NULL, ast_json_unref);
+	RAII_VAR(struct ast_json *, event, NULL, ast_json_unref);
+
+	if (extra_info) {
+		event = ast_json_deep_copy(extra_info);
+	} else {
+		event = ast_json_object_create();
+	}
+
+	if (snapshot) {
+		int ret;
+
+		/* Mustn't already have a channel field */
+		ast_assert(ast_json_object_get(event, "channel") == NULL);
+
+		ret = ast_json_object_set(
+			event,
+			"channel", ast_channel_snapshot_to_json(snapshot));
+		if (ret != 0) {
+			return NULL;
+		}
+	}
+
+	message = ast_json_pack("{s: o}", event_name, ast_json_ref(event));
+
+	return ast_json_ref(message);
+}
+
+static int send_start_msg(struct app *app, struct ast_channel *chan,
+			  int argc, char *argv[])
+{
+	RAII_VAR(struct ast_json *, msg, NULL, ast_json_unref);
+	RAII_VAR(struct ast_channel_snapshot *, snapshot, NULL, ao2_cleanup);
+
+	struct ast_json *json_args;
+	int i;
+
+	ast_assert(chan != NULL);
+
+	/* Set channel info */
+	snapshot = ast_channel_snapshot_create(chan);
+	if (!snapshot) {
+		return -1;
+	}
+
+	msg = ast_json_pack("{s: {s: [], s: o}}",
+			    "stasis-start",
+			    "args",
+			    "channel", ast_channel_snapshot_to_json(snapshot));
+
+	if (!msg) {
+		return -1;
+	}
+
+	/* Append arguments to args array */
+	json_args = ast_json_object_get(
+		ast_json_object_get(msg, "stasis-start"),
+		"args");
+	ast_assert(json_args != NULL);
+	for (i = 0; i < argc; ++i) {
+		int r = ast_json_array_append(json_args,
+					      ast_json_string_create(argv[i]));
+		if (r != 0) {
+			ast_log(LOG_ERROR, "Error appending start message\n");
+			return -1;
+		}
+	}
+
+	app_send(app, msg);
+	return 0;
+}
+
+static int send_end_msg(struct app *app, struct ast_channel *chan)
+{
+	RAII_VAR(struct ast_json *, msg, NULL, ast_json_unref);
+	RAII_VAR(struct ast_channel_snapshot *, snapshot, NULL, ao2_cleanup);
+
+	ast_assert(chan != NULL);
+
+	/* Set channel info */
+	snapshot = ast_channel_snapshot_create(chan);
+	if (snapshot == NULL) {
+		return -1;
+	}
+	msg = app_event_create("stasis-end", snapshot, NULL);
+	if (!msg) {
+		return -1;
+	}
+
+	app_send(app, msg);
+	return 0;
+}
+
+static void sub_handler(void *data, struct stasis_subscription *sub,
+			struct stasis_topic *topic,
+			struct stasis_message *message)
+{
+	struct app *app = data;
+	if (ast_channel_snapshot_type() == stasis_message_type(message)) {
+		RAII_VAR(struct ast_json *, msg, NULL, ast_json_unref);
+		struct ast_channel_snapshot *snapshot =
+			stasis_message_data(message);
+
+		msg = app_event_create("channel-state-change", snapshot, NULL);
+		if (!msg) {
+			return;
+		}
+		app_send(app, msg);
+	}
+	if (stasis_subscription_final_message(sub, message)) {
+		ao2_cleanup(data);
+	}
+}
+
+/*!
+ * \brief In addition to running ao2_cleanup(), this function also removes the
+ * object from the app_controls() container.
+ */
+static void control_unlink(struct stasis_app_control *control)
+{
+	RAII_VAR(struct ao2_container *, controls, NULL, ao2_cleanup);
+
+	if (!control) {
+		return;
+	}
+
+	controls = app_controls();
+	ao2_unlink_flags(controls, control, OBJ_POINTER | OBJ_UNLINK | OBJ_NODATA);
+	ao2_cleanup(control);
+}
+
+/*! /brief Stasis dialplan application callback */
+static int app_stasis_exec(struct ast_channel *chan, const char *data)
+{
+	RAII_VAR(struct ao2_container *, apps, apps_registry(), ao2_cleanup);
+	RAII_VAR(struct app *, app, NULL, ao2_cleanup);
+	RAII_VAR(struct stasis_app_control *, control, NULL, control_unlink);
+	RAII_VAR(struct stasis_subscription *, subscription, NULL, stasis_unsubscribe);
+	int res = 0;
+	char *parse = NULL;
+	int hungup = 0;
+
+	AST_DECLARE_APP_ARGS(args,
+		AST_APP_ARG(app_name);
+		AST_APP_ARG(app_argv)[MAX_ARGS];
+	);
+
+	ast_assert(chan != NULL);
+	ast_assert(data != NULL);
+
+	/* parse the arguments */
+	parse = ast_strdupa(data);
+	AST_STANDARD_APP_ARGS(args, parse);
+
+	if (args.argc < 1) {
+		ast_log(LOG_WARNING, "Stasis app_name argument missing\n");
+		return -1;
+	}
+
+	app = ao2_find(apps, args.app_name, OBJ_KEY);
+	if (!app) {
+		ast_log(LOG_ERROR, "Stasis app '%s' not registered\n", args.app_name);
+		return -1;
+	}
+
+	{
+		RAII_VAR(struct ao2_container *, controls, NULL, ao2_cleanup);
+
+		controls = app_controls();
+		control = control_create(ast_channel_uniqueid(chan));
+		if (!control) {
+			ast_log(LOG_ERROR, "Allocated failed\n");
+			return -1;
+		}
+		ao2_link(controls, control);
+	}
+
+	subscription = stasis_subscribe(ast_channel_topic(chan), sub_handler, app);
+	if (subscription == NULL) {
+		ast_log(LOG_ERROR, "Error subscribing app %s to channel %s\n", args.app_name, ast_channel_name(chan));
+		return -1;
+	}
+	ao2_ref(app, +1); /* subscription now has a reference */
+
+	res = send_start_msg(app, chan, args.argc - 1, args.app_argv);
+	if (res != 0) {
+		ast_log(LOG_ERROR, "Error sending start message to %s\n", args.app_name);
+		return res;
+	}
+
+	while (!hungup && !control_continue_test_and_reset(control) && ast_waitfor(chan, -1) > -1) {
+		RAII_VAR(struct ast_frame *, f, ast_read(chan), ast_frame_dtor);
+		if (!f) {
+			ast_debug(3, "%s: No more frames. Must be done, I guess.\n", ast_channel_uniqueid(chan));
+			break;
+		}
+
+		switch (f->frametype) {
+		case AST_FRAME_CONTROL:
+			if (f->subclass.integer == AST_CONTROL_HANGUP) {
+				ast_debug(3, "%s: Received hangup\n", ast_channel_uniqueid(chan));
+				hungup = 1;
+			}
+			break;
+		default:
+			/* Not handled; discard */
+			break;
+		}
+	}
+
+	res = send_end_msg(app, chan);
+	if (res != 0) {
+		ast_log(LOG_ERROR, "Error sending end message to %s\n", args.app_name);
+		return res;
+	}
+
+	return res;
+}
+
+int stasis_app_send(const char *app_name, struct ast_json *message)
+{
+	RAII_VAR(struct ao2_container *, apps, apps_registry(), ao2_cleanup);
+	RAII_VAR(struct app *, app, NULL, ao2_cleanup);
+
+	app = ao2_find(apps, app_name, OBJ_KEY);
+
+	if (!app) {
+		/* XXX We can do a better job handling late binding, queueing up the call for a few seconds
+		 * to wait for the app to register.
+		 */
+		ast_log(LOG_WARNING, "Stasis app '%s' not registered\n", app_name);
+		return -1;
+	}
+
+	app_send(app, message);
+	return 0;
+}
+
+int stasis_app_register(const char *app_name, stasis_app_cb handler, void *data)
+{
+	RAII_VAR(struct ao2_container *, apps, apps_registry(), ao2_cleanup);
+	RAII_VAR(struct app *, app, NULL, ao2_cleanup);
+
+	SCOPED_LOCK(apps_lock, apps, ao2_lock, ao2_unlock);
+
+	app = ao2_find(apps, app_name, OBJ_KEY | OBJ_NOLOCK);
+
+	if (app) {
+		RAII_VAR(struct ast_json *, msg, NULL, ast_json_unref);
+		SCOPED_LOCK(app_lock, app, ao2_lock, ao2_unlock);
+
+		msg = app_event_create("application-replaced", NULL, NULL);
+		app->handler(app->data, app_name, msg);
+
+		app->handler = handler;
+		ao2_cleanup(app->data);
+		ao2_ref(data, +1);
+		app->data = data;
+	} else {
+		app = app_create(app_name, handler, data);
+		if (app) {
+			ao2_link_flags(apps, app, OBJ_NOLOCK);
+		} else {
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+void stasis_app_unregister(const char *app_name)
+{
+	RAII_VAR(struct ao2_container *, apps, NULL, ao2_cleanup);
+
+	if (app_name) {
+		apps = apps_registry();
+		ao2_cleanup(ao2_find(apps, app_name, OBJ_KEY | OBJ_UNLINK));
+	}
+}
+
+static int load_module(void)
+{
+	int r = 0;
+
+	__apps_registry = ao2_container_alloc(APPS_NUM_BUCKETS, app_hash, app_compare);
+	if (__apps_registry == NULL) {
+		return AST_MODULE_LOAD_FAILURE;
+	}
+
+	__app_controls = ao2_container_alloc(CONTROLS_NUM_BUCKETS, app_hash, app_compare);
+	if (__app_controls == NULL) {
+		return AST_MODULE_LOAD_FAILURE;
+	}
+
+	r |= ast_register_application_xml(stasis, app_stasis_exec);
+	return r;
+}
+
+static int unload_module(void)
+{
+	int r = 0;
+
+	ao2_cleanup(__apps_registry);
+	__apps_registry = NULL;
+
+	ao2_cleanup(__app_controls);
+	__app_controls = NULL;
+
+	r |= ast_unregister_application(stasis);
+	return r;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS, "Stasis dialplan application",
+		.load = load_module,
+		.unload = unload_module);