main/endpoints.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * David M. Lee, II <[email protected]>
 *
 * 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 Asterisk endpoint API.
 *
 * \author David M. Lee, II <[email protected]>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/astobj2.h"
#include "asterisk/endpoints.h"
#include "asterisk/stasis.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/stasis_endpoints.h"
#include "asterisk/stasis_message_router.h"
#include "asterisk/stringfields.h"
#include "asterisk/_private.h"

/*! Buckets for endpoint->channel mappings. Keep it prime! */
#define ENDPOINT_CHANNEL_BUCKETS 127

/*! Buckets for endpoint hash. Keep it prime! */
#define ENDPOINT_BUCKETS 127

/*! Buckets for technology endpoints. */
#define TECH_ENDPOINT_BUCKETS 11

static struct ao2_container *endpoints;

static struct ao2_container *tech_endpoints;

struct ast_endpoint {
   AST_DECLARE_STRING_FIELDS(
      AST_STRING_FIELD(tech); /*!< Technology (SIP, IAX2, etc.). */
      AST_STRING_FIELD(resource);   /*!< Name, unique to the tech. */
      AST_STRING_FIELD(id);   /*!< tech/resource id */
      );
   /*! Endpoint's current state */
   enum ast_endpoint_state state;
   /*!
    * \brief Max channels for this endpoint. -1 means unlimited or unknown.
    *
    * Note that this simply documents the limits of an endpoint, and does
    * nothing to try to enforce the limit.
    */
   int max_channels;
   /*! Topic for this endpoint's messages */
   struct stasis_cp_single *topics;
   /*! Router for handling this endpoint's messages */
   struct stasis_message_router *router;
   /*! ast_str_container of channels associated with this endpoint */
   struct ao2_container *channel_ids;
   /*! Forwarding subscription from an endpoint to its tech endpoint */
   struct stasis_forward *tech_forward;
};

AO2_STRING_FIELD_HASH_FN(ast_endpoint, id)
AO2_STRING_FIELD_CMP_FN(ast_endpoint, id)

struct ast_endpoint *ast_endpoint_find_by_id(const char *id)
{
   struct ast_endpoint *endpoint = ao2_find(endpoints, id, OBJ_KEY);

   if (!endpoint) {
      endpoint = ao2_find(tech_endpoints, id, OBJ_KEY);
   }

   return endpoint;
}

struct stasis_topic *ast_endpoint_topic(struct ast_endpoint *endpoint)
{
   if (!endpoint) {
      return ast_endpoint_topic_all();
   }
   return stasis_cp_single_topic(endpoint->topics);
}

struct stasis_topic *ast_endpoint_topic_cached(struct ast_endpoint *endpoint)
{
   if (!endpoint) {
      return ast_endpoint_topic_all_cached();
   }
   return stasis_cp_single_topic_cached(endpoint->topics);
}

const char *ast_endpoint_state_to_string(enum ast_endpoint_state state)
{
   switch (state) {
   case AST_ENDPOINT_UNKNOWN:
      return "unknown";
   case AST_ENDPOINT_OFFLINE:
      return "offline";
   case AST_ENDPOINT_ONLINE:
      return "online";
   }
   return "?";
}

static void endpoint_publish_snapshot(struct ast_endpoint *endpoint)
{
   RAII_VAR(struct ast_endpoint_snapshot *, snapshot, NULL, ao2_cleanup);
   RAII_VAR(struct stasis_message *, message, NULL, ao2_cleanup);

   ast_assert(endpoint != NULL);
   ast_assert(endpoint->topics != NULL);

   if (!ast_endpoint_snapshot_type()) {
      return;
   }

   snapshot = ast_endpoint_snapshot_create(endpoint);
   if (!snapshot) {
      return;
   }
   message = stasis_message_create(ast_endpoint_snapshot_type(), snapshot);
   if (!message) {
      return;
   }
   stasis_publish(ast_endpoint_topic(endpoint), message);
}

static void endpoint_dtor(void *obj)
{
   struct ast_endpoint *endpoint = obj;

   /* The router should be shut down already */
   ast_assert(stasis_message_router_is_done(endpoint->router));
   ao2_cleanup(endpoint->router);
   endpoint->router = NULL;

   stasis_cp_single_unsubscribe(endpoint->topics);
   endpoint->topics = NULL;

   ao2_cleanup(endpoint->channel_ids);
   endpoint->channel_ids = NULL;

   ast_string_field_free_memory(endpoint);
}


int ast_endpoint_add_channel(struct ast_endpoint *endpoint,
   struct ast_channel *chan)
{
   ast_assert(chan != NULL);
   ast_assert(endpoint != NULL);
   ast_assert(!ast_strlen_zero(endpoint->resource));

   ast_channel_forward_endpoint(chan, endpoint);

   ao2_lock(endpoint);
   ast_str_container_add(endpoint->channel_ids, ast_channel_uniqueid(chan));
   ao2_unlock(endpoint);

   endpoint_publish_snapshot(endpoint);

   return 0;
}

/*! \brief Handler for channel snapshot update */
static void endpoint_cache_clear(void *data,
   struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_endpoint *endpoint = data;
   struct ast_channel_snapshot_update *update = stasis_message_data(message);

   /* Only when the channel is dead do we remove it */
   if (!ast_test_flag(&update->new_snapshot->flags, AST_FLAG_DEAD)) {
      return;
   }

   ast_assert(endpoint != NULL);

   ao2_lock(endpoint);
   ast_str_container_remove(endpoint->channel_ids, update->new_snapshot->base->uniqueid);
   ao2_unlock(endpoint);
   endpoint_publish_snapshot(endpoint);
}

static void endpoint_subscription_change(void *data,
   struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct stasis_endpoint *endpoint = data;

   if (stasis_subscription_final_message(sub, message)) {
      ao2_cleanup(endpoint);
   }
}

static struct ast_endpoint *endpoint_internal_create(const char *tech, const char *resource)
{
   RAII_VAR(struct ast_endpoint *, endpoint, NULL, ao2_cleanup);
   RAII_VAR(struct ast_endpoint *, tech_endpoint, NULL, ao2_cleanup);
   int r = 0;

   /* Get/create the technology endpoint */
   if (!ast_strlen_zero(resource)) {
      tech_endpoint = ao2_find(tech_endpoints, tech, OBJ_KEY);
      if (!tech_endpoint) {
         tech_endpoint = endpoint_internal_create(tech, NULL);
         if (!tech_endpoint) {
            return NULL;
         }
      }
   }

   endpoint = ao2_alloc(sizeof(*endpoint), endpoint_dtor);
   if (!endpoint) {
      return NULL;
   }

   endpoint->max_channels = -1;
   endpoint->state = AST_ENDPOINT_UNKNOWN;

   if (ast_string_field_init(endpoint, 80) != 0) {
      return NULL;
   }
   ast_string_field_set(endpoint, tech, tech);
   ast_string_field_set(endpoint, resource, S_OR(resource, ""));
   ast_string_field_build(endpoint, id, "%s%s%s",
      tech,
      !ast_strlen_zero(resource) ? "/" : "",
      S_OR(resource, ""));

   /* All access to channel_ids should be covered by the endpoint's
    * lock; no extra lock needed. */
   endpoint->channel_ids = ast_str_container_alloc_options(
      AO2_ALLOC_OPT_LOCK_NOLOCK, ENDPOINT_CHANNEL_BUCKETS);
   if (!endpoint->channel_ids) {
      return NULL;
   }

   if (!ast_strlen_zero(resource)) {
      char *topic_name;
      int ret;

      ret = ast_asprintf(&topic_name, "endpoint:%s", endpoint->id);
      if (ret < 0) {
         return NULL;
      }

      endpoint->topics = stasis_cp_single_create(ast_endpoint_cache_all(),
         topic_name);
      ast_free(topic_name);
      if (!endpoint->topics) {
         return NULL;
      }
      stasis_cp_single_accept_message_type(endpoint->topics, ast_endpoint_snapshot_type());
      stasis_cp_single_set_filter(endpoint->topics, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);

      endpoint->router = stasis_message_router_create_pool(ast_endpoint_topic(endpoint));
      if (!endpoint->router) {
         return NULL;
      }
      r |= stasis_message_router_add(endpoint->router,
         ast_channel_snapshot_type(), endpoint_cache_clear,
         endpoint);
      r |= stasis_message_router_add(endpoint->router,
         stasis_subscription_change_type(), endpoint_subscription_change,
         endpoint);
      if (r) {
         return NULL;
      }

      endpoint->tech_forward = stasis_forward_all(stasis_cp_single_topic(endpoint->topics),
         stasis_cp_single_topic(tech_endpoint->topics));

      endpoint_publish_snapshot(endpoint);
      ao2_link(endpoints, endpoint);
   } else {
      char *topic_name;
      int ret;

      ret = ast_asprintf(&topic_name, "endpoint:%s", endpoint->id);
      if (ret < 0) {
         return NULL;
      }

      endpoint->topics = stasis_cp_sink_create(ast_endpoint_cache_all(),
         topic_name);
      ast_free(topic_name);
      if (!endpoint->topics) {
         return NULL;
      }
      stasis_cp_single_accept_message_type(endpoint->topics, ast_endpoint_snapshot_type());
      stasis_cp_single_set_filter(endpoint->topics, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);

      ao2_link(tech_endpoints, endpoint);
   }

   ao2_ref(endpoint, +1);
   return endpoint;
}

struct ast_endpoint *ast_endpoint_create(const char *tech, const char *resource)
{
   if (ast_strlen_zero(tech)) {
      ast_log(LOG_ERROR, "Endpoint tech cannot be empty\n");
      return NULL;
   }

   if (ast_strlen_zero(resource)) {
      ast_log(LOG_ERROR, "Endpoint resource cannot be empty\n");
      return NULL;
   }

   return endpoint_internal_create(tech, resource);
}

static struct stasis_message *create_endpoint_snapshot_message(struct ast_endpoint *endpoint)
{
   RAII_VAR(struct ast_endpoint_snapshot *, snapshot, NULL, ao2_cleanup);

   if (!ast_endpoint_snapshot_type()) {
      return NULL;
   }

   snapshot = ast_endpoint_snapshot_create(endpoint);
   if (!snapshot) {
      return NULL;
   }

   return stasis_message_create(ast_endpoint_snapshot_type(), snapshot);
}

void ast_endpoint_shutdown(struct ast_endpoint *endpoint)
{
   RAII_VAR(struct stasis_message *, clear_msg, NULL, ao2_cleanup);

   if (endpoint == NULL) {
      return;
   }

   ao2_unlink(endpoints, endpoint);
   endpoint->tech_forward = stasis_forward_cancel(endpoint->tech_forward);

   clear_msg = create_endpoint_snapshot_message(endpoint);
   if (clear_msg) {
      RAII_VAR(struct stasis_message *, message, NULL, ao2_cleanup);
      message = stasis_cache_clear_create(clear_msg);
      if (message) {
         stasis_publish(ast_endpoint_topic(endpoint), message);
      }
   }

   /* Bump refcount to hold on to the router */
   ao2_ref(endpoint->router, +1);
   stasis_message_router_unsubscribe(endpoint->router);
}

const char *ast_endpoint_get_tech(const struct ast_endpoint *endpoint)
{
   if (!endpoint) {
      return NULL;
   }
   return endpoint->tech;
}

const char *ast_endpoint_get_resource(const struct ast_endpoint *endpoint)
{
   if (!endpoint) {
      return NULL;
   }
   return endpoint->resource;
}

const char *ast_endpoint_get_id(const struct ast_endpoint *endpoint)
{
   if (!endpoint) {
      return NULL;
   }
   return endpoint->id;
}

enum ast_endpoint_state ast_endpoint_get_state(const struct ast_endpoint *endpoint)
{
   if (!endpoint) {
      return AST_ENDPOINT_UNKNOWN;
   }
   return endpoint->state;
}

void ast_endpoint_set_state(struct ast_endpoint *endpoint,
   enum ast_endpoint_state state)
{
   ast_assert(endpoint != NULL);
   ast_assert(!ast_strlen_zero(endpoint->resource));

   ao2_lock(endpoint);
   endpoint->state = state;
   ao2_unlock(endpoint);
   endpoint_publish_snapshot(endpoint);
}

void ast_endpoint_set_max_channels(struct ast_endpoint *endpoint,
   int max_channels)
{
   ast_assert(endpoint != NULL);
   ast_assert(!ast_strlen_zero(endpoint->resource));

   ao2_lock(endpoint);
   endpoint->max_channels = max_channels;
   ao2_unlock(endpoint);
   endpoint_publish_snapshot(endpoint);
}

static void endpoint_snapshot_dtor(void *obj)
{
   struct ast_endpoint_snapshot *snapshot = obj;
   int channel;

   ast_assert(snapshot != NULL);

   for (channel = 0; channel < snapshot->num_channels; channel++) {
      ao2_ref(snapshot->channel_ids[channel], -1);
   }

   ast_string_field_free_memory(snapshot);
}

struct ast_endpoint_snapshot *ast_endpoint_snapshot_create(
   struct ast_endpoint *endpoint)
{
   struct ast_endpoint_snapshot *snapshot;
   int channel_count;
   struct ao2_iterator i;
   void *obj;
   SCOPED_AO2LOCK(lock, endpoint);

   ast_assert(endpoint != NULL);
   ast_assert(!ast_strlen_zero(endpoint->resource));

   channel_count = ao2_container_count(endpoint->channel_ids);

   snapshot = ao2_alloc_options(
      sizeof(*snapshot) + channel_count * sizeof(char *),
      endpoint_snapshot_dtor,
      AO2_ALLOC_OPT_LOCK_NOLOCK);

   if (!snapshot || ast_string_field_init(snapshot, 80) != 0) {
      ao2_cleanup(snapshot);
      return NULL;
   }

   ast_string_field_build(snapshot, id, "%s/%s", endpoint->tech,
      endpoint->resource);
   ast_string_field_set(snapshot, tech, endpoint->tech);
   ast_string_field_set(snapshot, resource, endpoint->resource);

   snapshot->state = endpoint->state;
   snapshot->max_channels = endpoint->max_channels;

   i = ao2_iterator_init(endpoint->channel_ids, 0);
   while ((obj = ao2_iterator_next(&i))) {
      /* The reference is kept so the channel id does not go away until the snapshot is gone */
      snapshot->channel_ids[snapshot->num_channels++] = obj;
   }
   ao2_iterator_destroy(&i);

   return snapshot;
}

static void endpoint_cleanup(void)
{
   ao2_cleanup(endpoints);
   endpoints = NULL;

   ao2_cleanup(tech_endpoints);
   tech_endpoints = NULL;
}

int ast_endpoint_init(void)
{
   ast_register_cleanup(endpoint_cleanup);

   endpoints = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, ENDPOINT_BUCKETS,
      ast_endpoint_hash_fn, NULL, ast_endpoint_cmp_fn);
   if (!endpoints) {
      return -1;
   }

   tech_endpoints = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      TECH_ENDPOINT_BUCKETS, ast_endpoint_hash_fn, NULL, ast_endpoint_cmp_fn);
   if (!tech_endpoints) {
      return -1;
   }

   return 0;
}