mwi.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2019, Sangoma Technologies Corporation
 *
 * Kevin Harwell <[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.
 */

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

#include "asterisk.h"

#include "asterisk/app.h"
#include "asterisk/mwi.h"
#include "asterisk/stasis_channels.h"

/*
 * @{ \brief Define \ref stasis topic objects
 */
static struct stasis_state_manager *mwi_state_manager;
static struct stasis_cache *mwi_state_cache;
static struct stasis_caching_topic *mwi_topic_cached;
/* @} */

/*! \brief Convert a MWI \ref stasis_message to a \ref ast_event */
static struct ast_event *mwi_to_event(struct stasis_message *message)
{
   struct ast_event *event;
   struct ast_mwi_state *mwi_state;
   char *mailbox;
   char *context;

   if (!message) {
      return NULL;
   }

   mwi_state = stasis_message_data(message);

   /* Strip off @context */
   context = mailbox = ast_strdupa(mwi_state->uniqueid);
   strsep(&context, "@");
   if (ast_strlen_zero(context)) {
      context = "default";
   }

   event = ast_event_new(AST_EVENT_MWI,
            AST_EVENT_IE_MAILBOX, AST_EVENT_IE_PLTYPE_STR, mailbox,
            AST_EVENT_IE_CONTEXT, AST_EVENT_IE_PLTYPE_STR, context,
            AST_EVENT_IE_NEWMSGS, AST_EVENT_IE_PLTYPE_UINT, mwi_state->new_msgs,
            AST_EVENT_IE_OLDMSGS, AST_EVENT_IE_PLTYPE_UINT, mwi_state->old_msgs,
            AST_EVENT_IE_EID, AST_EVENT_IE_PLTYPE_RAW, &mwi_state->eid, sizeof(mwi_state->eid),
            AST_EVENT_IE_END);

   return event;
}

/*
 * @{ \brief Define \ref stasis message types for MWI
 */
STASIS_MESSAGE_TYPE_DEFN(ast_mwi_state_type,
   .to_event = mwi_to_event, );
STASIS_MESSAGE_TYPE_DEFN(ast_mwi_vm_app_type);
/* @} */

static void mwi_state_dtor(void *obj)
{
   struct ast_mwi_state *mwi_state = obj;
   ast_string_field_free_memory(mwi_state);
   ao2_cleanup(mwi_state->snapshot);
   mwi_state->snapshot = NULL;
}

struct stasis_topic *ast_mwi_topic_all(void)
{
   return stasis_state_all_topic(mwi_state_manager);
}

struct stasis_cache *ast_mwi_state_cache(void)
{
   return mwi_state_cache;
}

struct stasis_topic *ast_mwi_topic_cached(void)
{
   return stasis_caching_get_topic(mwi_topic_cached);
}

struct stasis_topic *ast_mwi_topic(const char *uniqueid)
{
   return stasis_state_topic(mwi_state_manager, uniqueid);
}

static struct ast_mwi_state *mwi_create_state(const char *mailbox, const char *context,
   int urgent_msgs, int new_msgs, int old_msgs)
{
   struct ast_mwi_state *mwi_state;

   ast_assert(!ast_strlen_zero(mailbox));

   mwi_state = ao2_alloc(sizeof(*mwi_state), mwi_state_dtor);
   if (!mwi_state) {
      ast_log(LOG_ERROR, "Unable to create MWI state for mailbox '%s@%s'\n",
            mailbox, ast_strlen_zero(context) ? "" : context);
      return NULL;
   }

   if (ast_string_field_init(mwi_state, 256)) {
      ast_log(LOG_ERROR, "Unable to initialize MWI state for mailbox '%s@%s'\n",
            mailbox, ast_strlen_zero(context) ? "" : context);
      ao2_ref(mwi_state, -1);
      return NULL;
   }
   if (!ast_strlen_zero(context)) {
      ast_string_field_build(mwi_state, uniqueid, "%s@%s", mailbox, context);
   } else {
      ast_string_field_set(mwi_state, uniqueid, mailbox);
   }

   mwi_state->urgent_msgs = urgent_msgs;
   mwi_state->new_msgs = new_msgs;
   mwi_state->old_msgs = old_msgs;

   return mwi_state;
}

static struct ast_mwi_state *mwi_retrieve_then_create_state(const char *mailbox)
{
   int urgent_msgs;
   int new_msgs;
   int old_msgs;

   ast_app_inboxcount2(mailbox, &urgent_msgs, &new_msgs, &old_msgs);
   return mwi_create_state(mailbox, NULL, urgent_msgs, new_msgs, old_msgs);
}

struct ast_mwi_state *ast_mwi_create(const char *mailbox, const char *context)
{
   return mwi_create_state(mailbox, context, 0, 0, 0);
}

/*!
 * \internal
 * \brief Create a MWI state snapshot message.
 * \since 12.2.0
 *
 * \param[in] mailbox The mailbox identifier string.
 * \param[in] context The context this mailbox resides in (NULL or "" if only using mailbox)
 * \param[in] new_msgs The number of new messages in this mailbox
 * \param[in] old_msgs The number of old messages in this mailbox
 * \param[in] channel_id A unique identifier for a channel associated with this
 * change in mailbox state
 * \param[in] eid The EID of the server that originally published the message
 *
 * \retval message on success.  Use ao2_cleanup() when done with it.
 * \retval NULL on error.
 */
static struct stasis_message *mwi_state_create_message(
   const char *mailbox,
   const char *context,
   int urgent_msgs,
   int new_msgs,
   int old_msgs,
   const char *channel_id,
   struct ast_eid *eid)
{
   struct ast_mwi_state *mwi_state;
   struct stasis_message *message;

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

   mwi_state = mwi_create_state(mailbox, context, urgent_msgs, new_msgs, old_msgs);
   if (!mwi_state) {
      return NULL;
   }

   if (!ast_strlen_zero(channel_id)) {
      mwi_state->snapshot = ast_channel_snapshot_get_latest(channel_id);
   }

   if (eid) {
      mwi_state->eid = *eid;
   } else {
      mwi_state->eid = ast_eid_default;
   }

   /*
    * XXX As far as stasis is concerned, all MWI events are local.
    *
    * We may in the future want to make MWI aggregate local/remote
    * message counts similar to how device state aggregates state.
    */
   message = stasis_message_create_full(ast_mwi_state_type(), mwi_state, &ast_eid_default);
   ao2_cleanup(mwi_state);
   return message;
}

/*!
 * \internal
 *
 * This object currently acts as a typedef, but can also be thought of as a "child" object
 * of the stasis_state_subscriber type. As such the "base" pointer should always be the
 * first object attribute. Doing so allows this object to be easily type cast and used by
 * the stasis_state code.
 */
struct ast_mwi_subscriber {
   /*! The "base" state subscriber. (Must be first object attribute) */
   struct stasis_state_subscriber *base;
};

struct ast_mwi_subscriber *ast_mwi_add_subscriber(const char *mailbox)
{
   return (struct ast_mwi_subscriber *)stasis_state_add_subscriber(
      mwi_state_manager, mailbox);
}

struct ast_mwi_subscriber *ast_mwi_subscribe_pool(const char *mailbox,
   stasis_subscription_cb callback, void *data)
{
   struct stasis_subscription *stasis_sub;
   struct ast_mwi_subscriber *sub = (struct ast_mwi_subscriber *)stasis_state_subscribe_pool(
      mwi_state_manager, mailbox, callback, data);

   if (!sub) {
      return NULL;
   }

   stasis_sub = ast_mwi_subscriber_subscription(sub);

   stasis_subscription_accept_message_type(stasis_sub, ast_mwi_state_type());
   stasis_subscription_set_filter(stasis_sub, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);

   return sub;
}

void *ast_mwi_unsubscribe(struct ast_mwi_subscriber *sub)
{
   return stasis_state_unsubscribe((struct stasis_state_subscriber *)sub);
}

void *ast_mwi_unsubscribe_and_join(struct ast_mwi_subscriber *sub)
{
   return stasis_state_unsubscribe_and_join((struct stasis_state_subscriber *)sub);
}

struct stasis_topic *ast_mwi_subscriber_topic(struct ast_mwi_subscriber *sub)
{
   return stasis_state_subscriber_topic((struct stasis_state_subscriber *)sub);
}

struct ast_mwi_state *ast_mwi_subscriber_data(struct ast_mwi_subscriber *sub)
{
   struct stasis_state_subscriber *s = (struct stasis_state_subscriber *)sub;
   struct ast_mwi_state *mwi_state = stasis_state_subscriber_data(s);

   return mwi_state ?: mwi_retrieve_then_create_state(stasis_state_subscriber_id(s));
}

struct stasis_subscription *ast_mwi_subscriber_subscription(struct ast_mwi_subscriber *sub)
{
   return stasis_state_subscriber_subscription((struct stasis_state_subscriber *)sub);
}

/*!
 * \internal
 *
 * This object currently acts as a typedef, but can also be thought of as a "child" object
 * of the stasis_state_publisher type. As such the "base" pointer should always be the
 * first object attribute. Doing so allows this object to be easily type cast and used by
 * the stasis_state code.
 */
struct ast_mwi_publisher {
   /*! The "base" state publisher. (Must be first object attribute) */
   struct stasis_state_publisher *base;
};

struct ast_mwi_publisher *ast_mwi_add_publisher(const char *mailbox)
{
   return (struct ast_mwi_publisher *)stasis_state_add_publisher(
      mwi_state_manager, mailbox);
}

int ast_mwi_add_observer(struct ast_mwi_observer *observer)
{
   return stasis_state_add_observer(mwi_state_manager,
      (struct stasis_state_observer *)observer);
}

void ast_mwi_remove_observer(struct ast_mwi_observer *observer)
{
   stasis_state_remove_observer(mwi_state_manager,
      (struct stasis_state_observer *)observer);
}

struct mwi_handler_data {
   on_mwi_state handler;
   void *data;
};

static int handle_mwi_state(const char *id, struct stasis_message *msg, void *user_data)
{
   struct mwi_handler_data *d = user_data;
   struct ast_mwi_state *mwi_state = stasis_message_data(msg);
   int res;

   if (mwi_state) {
      return d->handler(mwi_state, d->data);
   }

   mwi_state = mwi_create_state(id, NULL, 0, 0, 0);
   if (!mwi_state) {
      return 0;
   }

   res = d->handler(mwi_state, d->data);
   ao2_ref(mwi_state, -1);
   return res;
}

void ast_mwi_state_callback_all(on_mwi_state handler, void *data)
{
   struct mwi_handler_data d = {
      .handler = handler,
      .data = data
   };

   stasis_state_callback_all(mwi_state_manager, handle_mwi_state, &d);
}

void ast_mwi_state_callback_subscribed(on_mwi_state handler, void *data)
{
   struct mwi_handler_data d = {
      .handler = handler,
      .data = data
   };

   stasis_state_callback_subscribed(mwi_state_manager, handle_mwi_state, &d);
}

int ast_mwi_publish(struct ast_mwi_publisher *pub, int urgent_msgs,
   int new_msgs, int old_msgs, const char *channel_id, struct ast_eid *eid)
{
   struct stasis_state_publisher *p = (struct stasis_state_publisher *)pub;
   struct stasis_message *msg = mwi_state_create_message(stasis_state_publisher_id(p),
      NULL, urgent_msgs, new_msgs, old_msgs, channel_id, eid);

   if (!msg) {
      return -1;
   }

   stasis_state_publish(p, msg);
   ao2_ref(msg, -1);

   return 0;
}

int ast_mwi_publish_by_mailbox(const char *mailbox, const char *context, int urgent_msgs,
   int new_msgs, int old_msgs, const char *channel_id, struct ast_eid *eid)
{
   struct ast_mwi_state *mwi_state;
   struct stasis_message *msg = mwi_state_create_message(
      mailbox, context, urgent_msgs, new_msgs, old_msgs, channel_id, eid);

   if (!msg) {
      return -1;
   }

   mwi_state = stasis_message_data(msg);
   stasis_state_publish_by_id(mwi_state_manager, mwi_state->uniqueid, NULL, msg);
   ao2_ref(msg, -1);

   return 0;
}

int ast_publish_mwi_state_full(
   const char *mailbox,
   const char *context,
   int new_msgs,
   int old_msgs,
   const char *channel_id,
   struct ast_eid *eid)
{
   return ast_mwi_publish_by_mailbox(mailbox, context, 0, new_msgs, old_msgs, channel_id, eid);
}

int ast_delete_mwi_state_full(const char *mailbox, const char *context, struct ast_eid *eid)
{
   RAII_VAR(struct stasis_message *, msg, NULL, ao2_cleanup);
   struct stasis_message *cached_msg;
   struct stasis_message *clear_msg;
   struct ast_mwi_state *mwi_state;

   msg = mwi_state_create_message(mailbox, context, 0, 0, 0, NULL, eid);
   if (!msg) {
      return -1;
   }

   mwi_state = stasis_message_data(msg);

   /*
    * XXX As far as stasis is concerned, all MWI events are local.
    *
    * For now, it is assumed that there is only one entity
    * maintaining the state of a particular mailbox.
    *
    * If we ever have multiple MWI event entities maintaining
    * the same mailbox that wish to delete their cached entry
    * we will need to do something about the race condition
    * potential between checking the cache and removing the
    * cache entry.
    */
   cached_msg = stasis_cache_get_by_eid(ast_mwi_state_cache(),
      ast_mwi_state_type(), mwi_state->uniqueid, &ast_eid_default);
   if (!cached_msg) {
      /* Nothing to clear from the cache, but still need to remove state */
      stasis_state_remove_publish_by_id(mwi_state_manager, mwi_state->uniqueid, eid, NULL);
      return -1;
   }
   ao2_cleanup(cached_msg);

   clear_msg = stasis_cache_clear_create(msg);
   stasis_state_remove_publish_by_id(mwi_state_manager, mwi_state->uniqueid, eid, clear_msg);
   ao2_cleanup(clear_msg);

   return 0;
}

static const char *mwi_state_get_id(struct stasis_message *message)
{
   if (ast_mwi_state_type() == stasis_message_type(message)) {
      struct ast_mwi_state *mwi_state = stasis_message_data(message);
      return mwi_state->uniqueid;
   } else if (stasis_subscription_change_type() == stasis_message_type(message)) {
      struct stasis_subscription_change *change = stasis_message_data(message);
      return change->uniqueid;
   }

   return NULL;
}

static void mwi_blob_dtor(void *obj)
{
   struct ast_mwi_blob *mwi_blob = obj;

   ao2_cleanup(mwi_blob->mwi_state);
   ast_json_unref(mwi_blob->blob);
}

struct stasis_message *ast_mwi_blob_create(struct ast_mwi_state *mwi_state,
                      struct stasis_message_type *message_type,
                      struct ast_json *blob)
{
   struct ast_mwi_blob *obj;
   struct stasis_message *msg;

   ast_assert(blob != NULL);

   if (!message_type) {
      return NULL;
   }

   obj = ao2_alloc(sizeof(*obj), mwi_blob_dtor);
   if (!obj) {
      return NULL;
   }

   obj->mwi_state = mwi_state;
   ao2_ref(obj->mwi_state, +1);
   obj->blob = ast_json_ref(blob);

   /* This is not a normal MWI event.  Only used by the MinivmNotify app. */
   msg = stasis_message_create(message_type, obj);
   ao2_ref(obj, -1);

   return msg;
}

static void mwi_cleanup(void)
{
   ao2_cleanup(mwi_state_cache);
   mwi_state_cache = NULL;
   mwi_topic_cached = stasis_caching_unsubscribe_and_join(mwi_topic_cached);
   ao2_cleanup(mwi_state_manager);
   mwi_state_manager = NULL;
   STASIS_MESSAGE_TYPE_CLEANUP(ast_mwi_state_type);
   STASIS_MESSAGE_TYPE_CLEANUP(ast_mwi_vm_app_type);
}

int mwi_init(void)
{
   ast_register_cleanup(mwi_cleanup);

   if (STASIS_MESSAGE_TYPE_INIT(ast_mwi_state_type) != 0) {
      return -1;
   }

   if (STASIS_MESSAGE_TYPE_INIT(ast_mwi_vm_app_type) != 0) {
      return -1;
   }

   mwi_state_manager = stasis_state_manager_create("mwi:all");
   if (!mwi_state_manager) {
      return -1;
   }

   mwi_state_cache = stasis_cache_create(mwi_state_get_id);
   if (!mwi_state_cache) {
      return -1;
   }

   mwi_topic_cached = stasis_caching_topic_create(ast_mwi_topic_all(), mwi_state_cache);
   if (!mwi_topic_cached) {
      return -1;
   }

   return 0;
}