Multiple revisions 420089-420090,420097

........
  r420089 | mjordan | 2014-08-05 15:10:52 -0500 (Tue, 05 Aug 2014) | 72 lines
  
  ARI: Add channel technology agnostic out of call text messaging
  
  This patch adds the ability to send and receive text messages from various
  technology stacks in Asterisk through ARI. This includes chan_sip (sip),
  res_pjsip_messaging (pjsip), and res_xmpp (xmpp). Messages are sent using the
  endpoints resource, and can be sent directly through that resource, or to a
  particular endpoint.
  
  For example, the following would send the message "Hello there" to PJSIP
  endpoint alice with a display URI of sip:asterisk@mycooldomain.org:
  
  ari/endpoints/sendMessage?to=pjsip:alice&from=sip:asterisk@mycooldomain.org&body=Hello+There
  
  This is equivalent to the following as well:
  
  ari/endpoints/PJSIP/alice/sendMessage?from=sip:asterisk@mycooldomain.org&body=Hello+There
  
  Both forms are available for message technologies that allow for arbitrary
  destinations, such as chan_sip.
  
  Inbound messages can now be received over ARI as well. An ARI application that
  subscribes to endpoints will receive messages from those endpoints:
  
  {
    "type": "TextMessageReceived",
    "timestamp": "2014-07-12T22:53:13.494-0500",
    "endpoint": {
      "technology": "PJSIP",
      "resource": "alice",
      "state": "online",
      "channel_ids": []
    },
    "message": {
      "from": "\"alice\" <sip:alice@127.0.0.1>",
      "to": "pjsip:asterisk@127.0.0.1",
      "body": "Watson, come here.",
      "variables": []
    },
    "application": "testsuite"
  }
  
  The above was made possible due to some rather major changes in the message
  core. This includes (but is not limited to):
  - Users of the message API can now register message handlers. A handler has
    two callbacks: one to determine if the handler has a destination for the
    message, and another to handle it.
  - All dialplan functionality of handling a message was moved into a message
    handler provided by the message API.
  - Messages can now have the technology/endpoint associated with them.
    Various other properties are also now more easily accessible.
  - A number of ao2 containers that weren't really needed were replaced with
    vectors. Iteration over ao2_containers is expensive and pointless when
    the lifetime of things is well defined and the number of things is very
    small.
  
  res_stasis now has a new file that makes up its structure, messaging. The
  messaging functionality implements a message handler, and passes received
  messages that match an interested endpoint over to the app for processing.
  
  Note that inadvertently while testing this, I reproduced ASTERISK-23969.
  res_pjsip_messaging was incorrectly parsing out the 'to' field, such that
  arbitrary SIP URIs mangled the endpoint lookup. This patch includes the
  fix for that as well.
  
  Review: https://reviewboard.asterisk.org/r/3726
  
  ASTERISK-23692 #close
  Reported by: Matt Jordan
  
  ASTERISK-23969 #close
  Reported by: Andrew Nagy
........
  r420090 | mjordan | 2014-08-05 15:16:37 -0500 (Tue, 05 Aug 2014) | 2 lines
  
  Remove automerge properties :-(
........
  r420097 | mjordan | 2014-08-05 16:36:25 -0500 (Tue, 05 Aug 2014) | 2 lines
  
  test_message: Fix strict-aliasing compilation issue
........

Merged revisions 420089-420090,420097 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@420098 65c4cc65-6c06-0410-ace0-fbb531ad65f3

3 files changed, 660 insertions, 0 deletions

diff --git a/res/stasis/app.c b/res/stasis/app.c
index 41f6ccf65..7e7911b9c 100644
--- a/res/stasis/app.c
+++ b/res/stasis/app.c
@@ -28,6 +28,7 @@
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
 #include "app.h"
+#include "messaging.h"
 
 #include "asterisk/callerid.h"
 #include "asterisk/stasis_app.h"
@@ -511,6 +512,44 @@ static struct ast_json *simple_endpoint_event(
 		"endpoint", json_endpoint);
 }
 
+static int message_received_handler(const char *endpoint_id, struct ast_json *json_msg, void *pvt)
+{
+	RAII_VAR(struct ast_endpoint_snapshot *, snapshot, NULL, ao2_cleanup);
+	struct ast_json *json_endpoint;
+	struct stasis_app *app = pvt;
+	char *tech;
+	char *resource;
+
+	tech = ast_strdupa(endpoint_id);
+	resource = strchr(tech, '/');
+	if (resource) {
+		resource[0] = '\0';
+		resource++;
+	}
+
+	if (ast_strlen_zero(tech) || ast_strlen_zero(resource)) {
+		return -1;
+	}
+
+	snapshot = ast_endpoint_latest_snapshot(tech, resource);
+	if (!snapshot) {
+		return -1;
+	}
+
+	json_endpoint = ast_endpoint_snapshot_to_json(snapshot, stasis_app_get_sanitizer());
+	if (!json_endpoint) {
+		return -1;
+	}
+
+	app_send(app, ast_json_pack("{s: s, s: o, s: o, s: O}",
+		"type", "TextMessageReceived",
+		"timestamp", ast_json_timeval(ast_tvnow(), NULL),
+		"endpoint", json_endpoint,
+		"message", json_msg));
+
+	return 0;
+}
+
 static void sub_endpoint_update_handler(void *data,
 	struct stasis_subscription *sub,
 	struct stasis_message *message)
@@ -1018,6 +1057,10 @@ static int unsubscribe(struct stasis_app *app, const char *kind, const char *id,
 		ao2_find(app->forwards, forwards,
 			OBJ_POINTER | OBJ_NOLOCK | OBJ_UNLINK |
 			OBJ_NODATA);
+
+		if (!strcmp(kind, "endpoint")) {
+			messaging_app_unsubscribe_endpoint(app->name, id);
+		}
 	}
 
 	return 0;
@@ -1148,6 +1191,9 @@ int app_subscribe_endpoint(struct stasis_app *app, struct ast_endpoint *endpoint
 				return -1;
 			}
 			ao2_link_flags(app->forwards, forwards, OBJ_NOLOCK);
+
+			/* Subscribe for messages */
+			messaging_app_subscribe_endpoint(app->name, endpoint, &message_received_handler, app);
 		}
 
 		++forwards->interested;
diff --git a/res/stasis/messaging.c b/res/stasis/messaging.c
new file mode 100644
index 000000000..47730851f
--- /dev/null
+++ b/res/stasis/messaging.c
@@ -0,0 +1,531 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2014, Digium, Inc.
+ *
+ * Matt Jordan <mjordan@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 out-of-call text message support
+ *
+ * \author Matt Jordan <mjordan@digium.com>
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/message.h"
+#include "asterisk/endpoints.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/vector.h"
+#include "asterisk/lock.h"
+#include "asterisk/utils.h"
+#include "asterisk/test.h"
+#include "messaging.h"
+
+/*!
+ * \brief Number of buckets for the \ref endpoint_subscriptions container
+ */
+#define ENDPOINTS_NUM_BUCKETS 127
+
+/*! \brief Storage object for an application */
+struct application_tuple {
+	/*! ao2 ref counted private object to pass to the callback */
+	void *pvt;
+	/*! The callback to call when this application has a message */
+	message_received_cb callback;
+	/*! The name (key) of the application */
+	char app_name[];
+};
+
+/*! \brief A subscription to some endpoint or technology */
+struct message_subscription {
+	/*! The applications that have subscribed to this endpoint or tech */
+	AST_VECTOR(, struct application_tuple *) applications;
+	/*! The name of this endpoint or tech */
+	char token[];
+};
+
+/*! \brief The subscriptions to endpoints */
+static struct ao2_container *endpoint_subscriptions;
+
+/*!
+ * \brief The subscriptions to technologies
+ *
+ * \note These are stored separately from standard endpoints, given how
+ * relatively few of them there are.
+ */
+static AST_VECTOR(,struct message_subscription *) tech_subscriptions;
+
+/*! \brief RWLock for \c tech_subscriptions */
+static ast_rwlock_t tech_subscriptions_lock;
+
+/*! \internal \brief Destructor for \c application_tuple */
+static void application_tuple_dtor(void *obj)
+{
+	struct application_tuple *tuple = obj;
+
+	ao2_cleanup(tuple->pvt);
+}
+
+/*! \internal \brief Constructor for \c application_tuple */
+static struct application_tuple *application_tuple_alloc(const char *app_name, message_received_cb callback, void *pvt)
+{
+	struct application_tuple *tuple;
+	size_t size = sizeof(*tuple) + strlen(app_name) + 1;
+
+	ast_assert(callback != NULL);
+
+	tuple = ao2_t_alloc(size, application_tuple_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
+	if (!tuple) {
+		return NULL;
+	}
+
+	strcpy(tuple->app_name, app_name); /* Safe */
+	tuple->pvt = ao2_bump(pvt);
+	tuple->callback = callback;
+
+	return tuple;
+}
+
+/*! \internal \brief Destructor for \ref message_subscription */
+static void message_subscription_dtor(void *obj)
+{
+	struct message_subscription *sub = obj;
+	int i;
+
+	for (i = 0; i < AST_VECTOR_SIZE(&sub->applications); i++) {
+		struct application_tuple *tuple = AST_VECTOR_GET(&sub->applications, i);
+
+		ao2_cleanup(tuple);
+	}
+	AST_VECTOR_FREE(&sub->applications);
+}
+
+/*! \internal \brief Constructor for \ref message_subscription */
+static struct message_subscription *message_subscription_alloc(const char *token)
+{
+	struct message_subscription *sub;
+	size_t size = sizeof(*sub) + strlen(token) + 1;
+
+	sub = ao2_t_alloc(size, message_subscription_dtor, AO2_ALLOC_OPT_LOCK_RWLOCK);
+	if (!sub) {
+		return NULL;
+	}
+	strcpy(sub->token, token); /* Safe */
+
+	return sub;
+}
+
+/*! AO2 hash function for \ref message_subscription */
+static int message_subscription_hash_cb(const void *obj, const int flags)
+{
+	const struct message_subscription *sub;
+	const char *key;
+
+	switch (flags & OBJ_SEARCH_MASK) {
+	case OBJ_SEARCH_KEY:
+		key = obj;
+		break;
+	case OBJ_SEARCH_OBJECT:
+		sub = obj;
+		key = sub->token;
+		break;
+	default:
+		/* Hash can only work on something with a full key. */
+		ast_assert(0);
+		return 0;
+	}
+	return ast_str_hash(key);
+}
+
+/*! AO2 comparison function for \ref message_subscription */
+static int message_subscription_compare_cb(void *obj, void *arg, int flags)
+{
+	const struct message_subscription *object_left = obj;
+	const struct message_subscription *object_right = arg;
+	const char *right_key = arg;
+	int cmp;
+
+	switch (flags & OBJ_SEARCH_MASK) {
+	case OBJ_SEARCH_OBJECT:
+		right_key = object_right->token;
+		/* Fall through */
+	case OBJ_SEARCH_KEY:
+		cmp = strcmp(object_left->token, right_key);
+		break;
+	case OBJ_SEARCH_PARTIAL_KEY:
+		/*
+		 * We could also use a partial key struct containing a length
+		 * so strlen() does not get called for every comparison instead.
+		 */
+		cmp = strncmp(object_left->token, right_key, strlen(right_key));
+		break;
+	default:
+		/*
+		 * What arg points to is specific to this traversal callback
+		 * and has no special meaning to astobj2.
+		 */
+		cmp = 0;
+		break;
+	}
+	if (cmp) {
+		return 0;
+	}
+	/*
+	 * At this point the traversal callback is identical to a sorted
+	 * container.
+	 */
+	return CMP_MATCH;
+}
+
+/*! \internal \brief Convert a \c ast_msg To/From URI to a Stasis endpoint name */
+static void msg_to_endpoint(const struct ast_msg *msg, char *buf, size_t len)
+{
+	const char *endpoint = ast_msg_get_endpoint(msg);
+
+	snprintf(buf, len, "%s%s%s", ast_msg_get_tech(msg),
+		ast_strlen_zero(endpoint) ? "" : "/",
+		S_OR(endpoint, ""));
+}
+
+/*! \internal
+ * \brief Callback from the \c message API that determines if we can handle
+ * this message
+ */
+static int has_destination_cb(const struct ast_msg *msg)
+{
+	struct message_subscription *sub;
+	int i;
+	char buf[256];
+
+	msg_to_endpoint(msg, buf, sizeof(buf));
+
+	ast_rwlock_rdlock(&tech_subscriptions_lock);
+	for (i = 0; i < AST_VECTOR_SIZE(&tech_subscriptions); i++) {
+		sub = AST_VECTOR_GET(&tech_subscriptions, i);
+
+		if (sub && (!strncasecmp(sub->token, buf, strlen(sub->token))
+		            || !strncasecmp(sub->token, buf, strlen(sub->token)))) {
+			ast_rwlock_unlock(&tech_subscriptions_lock);
+			sub = NULL; /* No ref bump! */
+			goto match;
+		}
+
+	}
+	ast_rwlock_unlock(&tech_subscriptions_lock);
+
+	sub = ao2_find(endpoint_subscriptions, buf, OBJ_SEARCH_KEY);
+	if (sub) {
+		goto match;
+	}
+
+	ast_debug(1, "No subscription found for %s\n", buf);
+	return 0;
+
+match:
+	ao2_cleanup(sub);
+	return 1;
+}
+
+static struct ast_json *msg_to_json(struct ast_msg *msg)
+{
+	struct ast_json *json_obj;
+	struct ast_json *json_vars;
+	struct ast_msg_var_iterator *it_vars;
+	const char *name;
+	const char *value;
+
+	it_vars = ast_msg_var_iterator_init(msg);
+	if (!it_vars) {
+		return NULL;
+	}
+
+	json_vars = ast_json_array_create();
+	if (!json_vars) {
+		return NULL;
+	}
+
+	while (ast_msg_var_iterator_next(msg, it_vars, &name, &value)) {
+		struct ast_json *json_tuple;
+
+		json_tuple = ast_json_pack("{s: s}", name, value);
+		if (!json_tuple) {
+			ast_json_free(json_vars);
+			return NULL;
+		}
+
+		ast_json_array_append(json_vars, json_tuple);
+		ast_msg_var_unref_current(it_vars);
+	}
+	ast_msg_var_iterator_destroy(it_vars);
+
+	json_obj = ast_json_pack("{s: s, s: s, s: s, s: o}",
+		"from", ast_msg_get_from(msg),
+		"to", ast_msg_get_to(msg),
+		"body", ast_msg_get_body(msg),
+		"variables", json_vars);
+
+	return json_obj;
+}
+
+static int handle_msg_cb(struct ast_msg *msg)
+{
+	struct message_subscription *sub;
+	int i;
+	char buf[256];
+	const char *endpoint_name;
+	struct ast_json *json_msg;
+
+	msg_to_endpoint(msg, buf, sizeof(buf));
+
+	ast_rwlock_rdlock(&tech_subscriptions_lock);
+	for (i = 0; i < AST_VECTOR_SIZE(&tech_subscriptions); i++) {
+		sub = AST_VECTOR_GET(&tech_subscriptions, i);
+
+		if (!sub) {
+			continue;
+		}
+
+		if (!strncasecmp(sub->token, buf, strlen(sub->token))) {
+			ast_rwlock_unlock(&tech_subscriptions_lock);
+			ao2_bump(sub);
+			endpoint_name = buf;
+			goto match;
+		}
+	}
+	ast_rwlock_unlock(&tech_subscriptions_lock);
+
+	sub = ao2_find(endpoint_subscriptions, buf, OBJ_SEARCH_KEY);
+	if (sub) {
+		endpoint_name = buf;
+		goto match;
+	}
+
+	return -1;
+
+match:
+	ast_debug(3, "Dispatching message for %s\n", endpoint_name);
+
+	json_msg = msg_to_json(msg);
+	if (!json_msg) {
+		ao2_ref(sub, -1);
+		return -1;
+	}
+
+	for (i = 0; i < AST_VECTOR_SIZE(&sub->applications); i++) {
+		struct application_tuple *tuple = AST_VECTOR_GET(&sub->applications, i);
+
+		tuple->callback(endpoint_name, json_msg, tuple->pvt);
+	}
+
+	ast_json_unref(json_msg);
+	ao2_ref(sub, -1);
+	return 0;
+}
+
+struct ast_msg_handler ari_msg_handler = {
+	.name = "ari",
+	.handle_msg = handle_msg_cb,
+	.has_destination = has_destination_cb,
+};
+
+static int messaging_subscription_cmp(struct message_subscription *sub, const char *key)
+{
+	return !strcmp(sub->token, key) ? 1 : 0;
+}
+
+static int application_tuple_cmp(struct application_tuple *item, const char *key)
+{
+	return !strcmp(item->app_name, key) ? 1 : 0;
+}
+
+static int is_app_subscribed(struct message_subscription *sub, const char *app_name)
+{
+	int i;
+
+	for (i = 0; i < AST_VECTOR_SIZE(&sub->applications); i++) {
+		struct application_tuple *tuple;
+
+		tuple = AST_VECTOR_GET(&sub->applications, i);
+		if (tuple && !strcmp(tuple->app_name, app_name)) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static struct message_subscription *get_subscription(struct ast_endpoint *endpoint)
+{
+	struct message_subscription *sub = NULL;
+
+	if (!ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
+		sub = ao2_find(endpoint_subscriptions, endpoint, OBJ_SEARCH_KEY);
+	} else {
+		int i;
+
+		ast_rwlock_rdlock(&tech_subscriptions_lock);
+		for (i = 0; i < AST_VECTOR_SIZE(&tech_subscriptions); i++) {
+			sub = AST_VECTOR_GET(&tech_subscriptions, i);
+
+			if (sub && !strcmp(sub->token, ast_endpoint_get_tech(endpoint))) {
+				ao2_bump(sub);
+				break;
+			}
+		}
+		ast_rwlock_unlock(&tech_subscriptions_lock);
+	}
+
+	return sub;
+}
+
+void messaging_app_unsubscribe_endpoint(const char *app_name, const char *endpoint_id)
+{
+	RAII_VAR(struct message_subscription *, sub, NULL, ao2_cleanup);
+	RAII_VAR(struct ast_endpoint *, endpoint, NULL, ao2_cleanup);
+
+	endpoint = ast_endpoint_find_by_id(endpoint_id);
+	if (!endpoint) {
+		return;
+	}
+
+	sub = get_subscription(endpoint);
+	if (!sub) {
+		return;
+	}
+
+	ao2_lock(sub);
+	if (!is_app_subscribed(sub, app_name)) {
+		ao2_unlock(sub);
+		return;
+	}
+
+	AST_VECTOR_REMOVE_CMP_UNORDERED(&sub->applications, app_name, application_tuple_cmp, ao2_cleanup);
+	if (AST_VECTOR_SIZE(&sub->applications) == 0) {
+		if (!ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
+			ao2_unlink(endpoint_subscriptions, sub);
+		} else {
+			ast_rwlock_wrlock(&tech_subscriptions_lock);
+			AST_VECTOR_REMOVE_CMP_UNORDERED(&tech_subscriptions, ast_endpoint_get_id(endpoint),
+				messaging_subscription_cmp, AST_VECTOR_ELEM_CLEANUP_NOOP);
+			ast_rwlock_unlock(&tech_subscriptions_lock);
+		}
+	}
+	ao2_unlock(sub);
+	ao2_ref(sub, -1);
+
+	ast_debug(3, "App '%s' unsubscribed to messages from endpoint '%s'\n", app_name, ast_endpoint_get_id(endpoint));
+	ast_test_suite_event_notify("StasisMessagingSubscription", "SubState: Unsubscribed\r\nAppName: %s\r\nToken: %s\r\n",
+		app_name, ast_endpoint_get_id(endpoint));
+}
+
+static struct message_subscription *get_or_create_subscription(struct ast_endpoint *endpoint)
+{
+	struct message_subscription *sub = get_subscription(endpoint);
+
+	if (sub) {
+		return sub;
+	}
+
+	sub = message_subscription_alloc(ast_endpoint_get_id(endpoint));
+	if (!sub) {
+		return NULL;
+	}
+
+	if (!ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
+		ao2_link(endpoint_subscriptions, sub);
+	} else {
+		ast_rwlock_wrlock(&tech_subscriptions_lock);
+		AST_VECTOR_APPEND(&tech_subscriptions, ao2_bump(sub));
+		ast_rwlock_unlock(&tech_subscriptions_lock);
+	}
+
+	return sub;
+}
+
+int messaging_app_subscribe_endpoint(const char *app_name, struct ast_endpoint *endpoint, message_received_cb callback, void *pvt)
+{
+	RAII_VAR(struct message_subscription *, sub, NULL, ao2_cleanup);
+	struct application_tuple *tuple;
+
+	sub = get_or_create_subscription(endpoint);
+	if (!sub) {
+		return -1;
+	}
+
+	ao2_lock(sub);
+	if (is_app_subscribed(sub, app_name)) {
+		ao2_unlock(sub);
+		return 0;
+	}
+
+	tuple = application_tuple_alloc(app_name, callback, pvt);
+	if (!tuple) {
+		ao2_unlock(sub);
+		return -1;
+	}
+	AST_VECTOR_APPEND(&sub->applications, tuple);
+	ao2_unlock(sub);
+
+	ast_debug(3, "App '%s' subscribed to messages from endpoint '%s'\n", app_name, ast_endpoint_get_id(endpoint));
+	ast_test_suite_event_notify("StasisMessagingSubscription", "SubState: Subscribed\r\nAppName: %s\r\nToken: %s\r\n",
+		app_name, ast_endpoint_get_id(endpoint));
+
+	return 0;
+}
+
+
+int messaging_cleanup(void)
+{
+	ast_msg_handler_unregister(&ari_msg_handler);
+	ao2_ref(endpoint_subscriptions, -1);
+	AST_VECTOR_FREE(&tech_subscriptions);
+	ast_rwlock_destroy(&tech_subscriptions_lock);\
+
+	return 0;
+}
+
+int messaging_init(void)
+{
+	endpoint_subscriptions = ao2_t_container_alloc_hash(AO2_ALLOC_OPT_LOCK_RWLOCK, 0,
+		ENDPOINTS_NUM_BUCKETS, message_subscription_hash_cb, NULL,
+		message_subscription_compare_cb, "Endpoint messaging subscription container creation");
+	if (!endpoint_subscriptions) {
+		return -1;
+	}
+
+	if (AST_VECTOR_INIT(&tech_subscriptions, 4)) {
+		ao2_ref(endpoint_subscriptions, -1);
+		return -1;
+	}
+
+	if (ast_rwlock_init(&tech_subscriptions_lock)) {
+		ao2_ref(endpoint_subscriptions, -1);
+		AST_VECTOR_FREE(&tech_subscriptions);
+		return -1;
+	}
+
+	if (ast_msg_handler_register(&ari_msg_handler)) {
+		ao2_ref(endpoint_subscriptions, -1);
+		AST_VECTOR_FREE(&tech_subscriptions);
+		ast_rwlock_destroy(&tech_subscriptions_lock);
+		return -1;
+	}
+
+	return 0;
+}
diff --git a/res/stasis/messaging.h b/res/stasis/messaging.h
new file mode 100644
index 000000000..c69d5d570
--- /dev/null
+++ b/res/stasis/messaging.h
@@ -0,0 +1,83 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2014, Digium, Inc.
+ *
+ * Matt Jordan <mjordan@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.
+ */
+
+#ifndef _ASTERISK_RES_STASIS_MESSAGING_H
+#define _ASTERISK_RES_STASIS_MESSAGING_H
+
+/*!
+ * \file
+ *
+ * \brief Stasis out-of-call text message support
+ *
+ * \author Matt Jordan <mjordan@digium.com>
+ * \since 12.4.0
+ */
+
+/*!
+ * \brief Callback handler for when a message is received from the core
+ *
+ * \param endpoint_id The ID of the endpoint that we received the message from
+ * \param json_msg JSON representation of the text message
+ * \param pvt ao2 ref counted pvt passed during registration
+ *
+ * \retval 0 the message was handled
+ * \retval non-zero the message was not handled
+ */
+typedef int (* message_received_cb)(const char *endpoint_id, struct ast_json *json_msg, void *pvt);
+
+/*!
+ * \brief Subscribe for messages from a particular endpoint
+ *
+ * \param app_name Name of the stasis application to unsubscribe from messaging
+ * \param endpoint_id The ID of the endpoint we no longer care about
+ *
+ * \retval 0 success
+ * \retval -1 error
+ */
+void messaging_app_unsubscribe_endpoint(const char *app_name, const char *endpoint_id);
+
+/*!
+ * \brief Subscribe an application to an endpoint for messages
+ *
+ * \param app_name The name of the \ref stasis application to subscribe to \c endpoint
+ * \param endpoint The endpoint object to subscribe to
+ * \param message_received_cb The callback to call when a message is received
+ * \param pvt An ao2 ref counted object that will be passed to the callback.
+ *
+ * \retval 0 subscription was successful
+ * \retval -1 subscription failed
+ */
+int messaging_app_subscribe_endpoint(const char *app_name, struct ast_endpoint *endpoint, message_received_cb callback, void *pvt);
+
+/*!
+ * \brief Tidy up the messaging layer
+ *
+ * \retval 0 success
+ * \retval -1 failure
+ */
+int messaging_cleanup(void);
+
+/*!
+ * \brief Initialize the messaging layer
+ *
+ * \retval 0 success
+ * \retval -1 failure
+ */
+int messaging_init(void);
+
+#endif /* #define _ASTERISK_RES_STASIS_MESSAGING_H  */
\ No newline at end of file