event.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007 - 2008, Digium, Inc.
 *
 * Russell Bryant <russell@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 Internal generic event system
 *
 * \author Russell Bryant <russell@digium.com>
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 337600 $")

#include "asterisk/_private.h"

#include "asterisk/event.h"
#include "asterisk/linkedlists.h"
#include "asterisk/dlinkedlists.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"
#include "asterisk/unaligned.h"
#include "asterisk/utils.h"
#include "asterisk/taskprocessor.h"
#include "asterisk/astobj2.h"
#include "asterisk/cli.h"

static struct ast_taskprocessor *event_dispatcher;

/*!
 * \brief An event information element
 *
 * \note The format of this structure is important.  Since these events may
 *       be sent directly over a network, changing this structure will break
 *       compatibility with older versions.  However, at this point, this code
 *       has not made it into a release, so it is still fair game for change.
 */
struct ast_event_ie {
   enum ast_event_ie_type ie_type:16;
   /*! Total length of the IE payload */
   uint16_t ie_payload_len;
   unsigned char ie_payload[0];
} __attribute__((packed));

/*!
 * \brief The payload for a string information element
 */
struct ast_event_ie_str_payload {
   /*! \brief A hash calculated with ast_str_hash(), to speed up comparisons */
   uint32_t hash;
   /*! \brief The actual string, null terminated */
   char str[1];
} __attribute__((packed));

/*!
 * \brief An event
 *
 * An ast_event consists of an event header (this structure), and zero or
 * more information elements defined by ast_event_ie.
 *
 * \note The format of this structure is important.  Since these events may
 *       be sent directly over a network, changing this structure will break
 *       compatibility with older versions.  However, at this point, this code
 *       has not made it into a release, so it is still fair game for change.
 */
struct ast_event {
   /*! Event type */
   enum ast_event_type type:16;
   /*! Total length of the event */
   uint16_t event_len:16;
   /*! The data payload of the event, made up of information elements */
   unsigned char payload[0];
} __attribute__((packed));


/*!
 * \brief A holder for an event
 *
 * \details This struct used to have more of a purpose than it does now.
 * It is used to hold events in the event cache.  It can be completely removed
 * if one of these two things is done:
 *  - ast_event gets changed such that it never has to be realloc()d
 *  - astobj2 is updated so that you can realloc() an astobj2 object
 */
struct ast_event_ref {
   struct ast_event *event;
};

struct ast_event_ie_val {
   AST_LIST_ENTRY(ast_event_ie_val) entry;
   enum ast_event_ie_type ie_type;
   enum ast_event_ie_pltype ie_pltype;
   union {
      uint32_t uint;
      struct {
         uint32_t hash;
         const char *str;
      };
      void *raw;
   } payload;
   size_t raw_datalen;
};

/*! \brief Event subscription */
struct ast_event_sub {
   enum ast_event_type type;
   ast_event_cb_t cb;
   char description[64];
   void *userdata;
   uint32_t uniqueid;
   AST_LIST_HEAD_NOLOCK(, ast_event_ie_val) ie_vals;
   AST_RWDLLIST_ENTRY(ast_event_sub) entry;
};

static uint32_t sub_uniqueid;

/*! \brief Event subscriptions
 * The event subscribers are indexed by which event they are subscribed to */
static AST_RWDLLIST_HEAD(ast_event_sub_list, ast_event_sub) ast_event_subs[AST_EVENT_TOTAL];

static int ast_event_cmp(void *obj, void *arg, int flags);
static int ast_event_hash_mwi(const void *obj, const int flags);
static int ast_event_hash_devstate(const void *obj, const int flags);
static int ast_event_hash_devstate_change(const void *obj, const int flags);

#ifdef LOW_MEMORY
#define NUM_CACHE_BUCKETS 17
#else
#define NUM_CACHE_BUCKETS 563
#endif

#define MAX_CACHE_ARGS 8

/*!
 * \brief Event types that are kept in the cache.
 */
static struct {
   /*! 
    * \brief Container of cached events
    *
    * \details This gets allocated in ast_event_init() when Asterisk starts
    * for the event types declared as using the cache.
    */
   struct ao2_container *container;
   /*! \brief Event type specific hash function */
   ao2_hash_fn *hash_fn;
   /*!
    * \brief Information Elements used for caching
    *
    * \details This array is the set of information elements that will be unique
    * among all events in the cache for this event type.  When a new event gets
    * cached, a previous event with the same values for these information elements
    * will be replaced.
    */
   enum ast_event_ie_type cache_args[MAX_CACHE_ARGS];
} ast_event_cache[AST_EVENT_TOTAL] = {
   [AST_EVENT_MWI] = {
      .hash_fn = ast_event_hash_mwi,
      .cache_args = { AST_EVENT_IE_MAILBOX, AST_EVENT_IE_CONTEXT },
   },
   [AST_EVENT_DEVICE_STATE] = {
      .hash_fn = ast_event_hash_devstate,
      .cache_args = { AST_EVENT_IE_DEVICE, },
   },
   [AST_EVENT_DEVICE_STATE_CHANGE] = {
      .hash_fn = ast_event_hash_devstate_change,
      .cache_args = { AST_EVENT_IE_DEVICE, AST_EVENT_IE_EID, },
   },
};

/*!
 * \brief Names of cached event types, for CLI tab completion
 *
 * \note These names must match what is in the event_names array.
 */
static const char * const cached_event_types[] = { "MWI", "DeviceState", "DeviceStateChange", NULL };

/*!
 * \brief Event Names
 */
static const char * const event_names[AST_EVENT_TOTAL] = {
   [AST_EVENT_ALL]                 = "All",
   [AST_EVENT_CUSTOM]              = "Custom",
   [AST_EVENT_MWI]                 = "MWI",
   [AST_EVENT_SUB]                 = "Subscription",
   [AST_EVENT_UNSUB]               = "Unsubscription",
   [AST_EVENT_DEVICE_STATE]        = "DeviceState",
   [AST_EVENT_DEVICE_STATE_CHANGE] = "DeviceStateChange",
   [AST_EVENT_CEL]                 = "CEL",
   [AST_EVENT_SECURITY]            = "Security",
   [AST_EVENT_NETWORK_CHANGE]      = "NetworkChange",
};

/*!
 * \brief IE payload types and names
 */
static const struct ie_map {
   enum ast_event_ie_pltype ie_pltype;
   const char *name;
} ie_maps[AST_EVENT_IE_TOTAL] = {
   [AST_EVENT_IE_NEWMSGS]             = { AST_EVENT_IE_PLTYPE_UINT, "NewMessages" },
   [AST_EVENT_IE_OLDMSGS]             = { AST_EVENT_IE_PLTYPE_UINT, "OldMessages" },
   [AST_EVENT_IE_MAILBOX]             = { AST_EVENT_IE_PLTYPE_STR,  "Mailbox" },
   [AST_EVENT_IE_UNIQUEID]            = { AST_EVENT_IE_PLTYPE_UINT, "UniqueID" },
   [AST_EVENT_IE_EVENTTYPE]           = { AST_EVENT_IE_PLTYPE_UINT, "EventType" },
   [AST_EVENT_IE_EXISTS]              = { AST_EVENT_IE_PLTYPE_UINT, "Exists" },
   [AST_EVENT_IE_DEVICE]              = { AST_EVENT_IE_PLTYPE_STR,  "Device" },
   [AST_EVENT_IE_STATE]               = { AST_EVENT_IE_PLTYPE_UINT, "State" },
   [AST_EVENT_IE_CONTEXT]             = { AST_EVENT_IE_PLTYPE_STR,  "Context" },
   [AST_EVENT_IE_EID]                 = { AST_EVENT_IE_PLTYPE_RAW,  "EntityID" },
   [AST_EVENT_IE_CEL_EVENT_TYPE]      = { AST_EVENT_IE_PLTYPE_UINT, "CELEventType" },
   [AST_EVENT_IE_CEL_EVENT_TIME]      = { AST_EVENT_IE_PLTYPE_UINT, "CELEventTime" },
   [AST_EVENT_IE_CEL_EVENT_TIME_USEC] = { AST_EVENT_IE_PLTYPE_UINT, "CELEventTimeUSec" },
   [AST_EVENT_IE_CEL_USEREVENT_NAME]  = { AST_EVENT_IE_PLTYPE_UINT, "CELUserEventName" },
   [AST_EVENT_IE_CEL_CIDNAME]         = { AST_EVENT_IE_PLTYPE_STR,  "CELCIDName" },
   [AST_EVENT_IE_CEL_CIDNUM]          = { AST_EVENT_IE_PLTYPE_STR,  "CELCIDNum" },
   [AST_EVENT_IE_CEL_EXTEN]           = { AST_EVENT_IE_PLTYPE_STR,  "CELExten" },
   [AST_EVENT_IE_CEL_CONTEXT]         = { AST_EVENT_IE_PLTYPE_STR,  "CELContext" },
   [AST_EVENT_IE_CEL_CHANNAME]        = { AST_EVENT_IE_PLTYPE_STR,  "CELChanName" },
   [AST_EVENT_IE_CEL_APPNAME]         = { AST_EVENT_IE_PLTYPE_STR,  "CELAppName" },
   [AST_EVENT_IE_CEL_APPDATA]         = { AST_EVENT_IE_PLTYPE_STR,  "CELAppData" },
   [AST_EVENT_IE_CEL_AMAFLAGS]        = { AST_EVENT_IE_PLTYPE_STR,  "CELAMAFlags" },
   [AST_EVENT_IE_CEL_ACCTCODE]        = { AST_EVENT_IE_PLTYPE_UINT, "CELAcctCode" },
   [AST_EVENT_IE_CEL_UNIQUEID]        = { AST_EVENT_IE_PLTYPE_STR,  "CELUniqueID" },
   [AST_EVENT_IE_CEL_USERFIELD]       = { AST_EVENT_IE_PLTYPE_STR,  "CELUserField" },
   [AST_EVENT_IE_CEL_CIDANI]          = { AST_EVENT_IE_PLTYPE_STR,  "CELCIDani" },
   [AST_EVENT_IE_CEL_CIDRDNIS]        = { AST_EVENT_IE_PLTYPE_STR,  "CELCIDrdnis" },
   [AST_EVENT_IE_CEL_CIDDNID]         = { AST_EVENT_IE_PLTYPE_STR,  "CELCIDdnid" },
   [AST_EVENT_IE_CEL_PEER]            = { AST_EVENT_IE_PLTYPE_STR,  "CELPeer" },
   [AST_EVENT_IE_CEL_LINKEDID]        = { AST_EVENT_IE_PLTYPE_STR,  "CELLinkedID" },
   [AST_EVENT_IE_CEL_PEERACCT]        = { AST_EVENT_IE_PLTYPE_STR,  "CELPeerAcct" },
   [AST_EVENT_IE_CEL_EXTRA]           = { AST_EVENT_IE_PLTYPE_STR,  "CELExtra" },
   [AST_EVENT_IE_SECURITY_EVENT]      = { AST_EVENT_IE_PLTYPE_STR,  "SecurityEvent" },
   [AST_EVENT_IE_EVENT_VERSION]       = { AST_EVENT_IE_PLTYPE_UINT, "EventVersion" },
   [AST_EVENT_IE_SERVICE]             = { AST_EVENT_IE_PLTYPE_STR,  "Service" },
   [AST_EVENT_IE_MODULE]              = { AST_EVENT_IE_PLTYPE_STR,  "Module" },
   [AST_EVENT_IE_ACCOUNT_ID]          = { AST_EVENT_IE_PLTYPE_STR,  "AccountID" },
   [AST_EVENT_IE_SESSION_ID]          = { AST_EVENT_IE_PLTYPE_STR,  "SessionID" },
   [AST_EVENT_IE_SESSION_TV]          = { AST_EVENT_IE_PLTYPE_STR,  "SessionTV" },
   [AST_EVENT_IE_ACL_NAME]            = { AST_EVENT_IE_PLTYPE_STR,  "ACLName" },
   [AST_EVENT_IE_LOCAL_ADDR]          = { AST_EVENT_IE_PLTYPE_STR,  "LocalAddress" },
   [AST_EVENT_IE_REMOTE_ADDR]         = { AST_EVENT_IE_PLTYPE_STR,  "RemoteAddress" },
   [AST_EVENT_IE_EVENT_TV]            = { AST_EVENT_IE_PLTYPE_STR,  "EventTV" },
   [AST_EVENT_IE_REQUEST_TYPE]        = { AST_EVENT_IE_PLTYPE_STR,  "RequestType" },
   [AST_EVENT_IE_REQUEST_PARAMS]      = { AST_EVENT_IE_PLTYPE_STR,  "RequestParams" },
   [AST_EVENT_IE_AUTH_METHOD]         = { AST_EVENT_IE_PLTYPE_STR,  "AuthMethod" },
   [AST_EVENT_IE_SEVERITY]            = { AST_EVENT_IE_PLTYPE_STR,  "Severity" },
   [AST_EVENT_IE_EXPECTED_ADDR]       = { AST_EVENT_IE_PLTYPE_STR,  "ExpectedAddress" },
   [AST_EVENT_IE_CHALLENGE]           = { AST_EVENT_IE_PLTYPE_STR,  "Challenge" },
   [AST_EVENT_IE_RESPONSE]            = { AST_EVENT_IE_PLTYPE_STR,  "Response" },
   [AST_EVENT_IE_EXPECTED_RESPONSE]   = { AST_EVENT_IE_PLTYPE_STR,  "ExpectedResponse" },
   [AST_EVENT_IE_RECEIVED_CHALLENGE]  = { AST_EVENT_IE_PLTYPE_STR,  "ReceivedChallenge" },
   [AST_EVENT_IE_RECEIVED_HASH]       = { AST_EVENT_IE_PLTYPE_STR,  "ReceivedHash" },
   [AST_EVENT_IE_USING_PASSWORD]      = { AST_EVENT_IE_PLTYPE_UINT, "UsingPassword" },

};

const char *ast_event_get_type_name(const struct ast_event *event)
{
   enum ast_event_type type;

   type = ast_event_get_type(event);

   if (type < 0 || type >= ARRAY_LEN(event_names)) {
      ast_log(LOG_ERROR, "Invalid event type - '%d'\n", type);
      return "";
   }

   return event_names[type];
}

int ast_event_str_to_event_type(const char *str, enum ast_event_type *event_type)
{
   int i;

   for (i = 0; i < ARRAY_LEN(event_names); i++) {
      if (ast_strlen_zero(event_names[i]) || strcasecmp(event_names[i], str)) {
         continue;
      }

      *event_type = i;
      return 0;
   }

   return -1;
}

const char *ast_event_get_ie_type_name(enum ast_event_ie_type ie_type)
{
   if (ie_type <= 0 || ie_type >= ARRAY_LEN(ie_maps)) {
      ast_log(LOG_ERROR, "Invalid IE type - '%d'\n", ie_type);
      return "";
   }

   return ie_maps[ie_type].name;
}

enum ast_event_ie_pltype ast_event_get_ie_pltype(enum ast_event_ie_type ie_type)
{
   if (ie_type <= 0 || ie_type >= ARRAY_LEN(ie_maps)) {
      ast_log(LOG_ERROR, "Invalid IE type - '%d'\n", ie_type);
      return AST_EVENT_IE_PLTYPE_UNKNOWN;
   }

   return ie_maps[ie_type].ie_pltype;
}

int ast_event_str_to_ie_type(const char *str, enum ast_event_ie_type *ie_type)
{
   int i;

   for (i = 0; i < ARRAY_LEN(ie_maps); i++) {
      if (strcasecmp(ie_maps[i].name, str)) {
         continue;
      }

      *ie_type = i;
      return 0;
   }

   return -1;
}

size_t ast_event_get_size(const struct ast_event *event)
{
   size_t res;

   res = ntohs(event->event_len);

   return res;
}

static void ast_event_ie_val_destroy(struct ast_event_ie_val *ie_val)
{
   switch (ie_val->ie_pltype) {
   case AST_EVENT_IE_PLTYPE_STR:
      ast_free((char *) ie_val->payload.str);
      break;
   case AST_EVENT_IE_PLTYPE_RAW:
      ast_free(ie_val->payload.raw);
      break;
   case AST_EVENT_IE_PLTYPE_UINT:
   case AST_EVENT_IE_PLTYPE_BITFLAGS:
   case AST_EVENT_IE_PLTYPE_EXISTS:
   case AST_EVENT_IE_PLTYPE_UNKNOWN:
      break;
   }

   ast_free(ie_val);
}

/*! \brief Subscription event check list. */
struct ast_ev_check_list {
   AST_LIST_HEAD_NOLOCK(, ast_event_ie_val) ie_vals;
};

/*!
 * \internal
 * \brief Check if a subscription ie_val matches an event.
 *
 * \param sub_ie_val Subscripton IE value to check
 * \param check_ie_vals event list to check against
 *
 * \retval 0 not matched
 * \retval non-zero matched
 */
static int match_sub_ie_val_to_event(const struct ast_event_ie_val *sub_ie_val, const struct ast_ev_check_list *check_ie_vals)
{
   const struct ast_event_ie_val *event_ie_val;
   int res = 0;

   AST_LIST_TRAVERSE(&check_ie_vals->ie_vals, event_ie_val, entry) {
      if (sub_ie_val->ie_type == event_ie_val->ie_type) {
         break;
      }
   }
   if (!event_ie_val) {
      /* We did not find the event ie the subscriber cares about. */
      return 0;
   }

   if (sub_ie_val->ie_pltype != event_ie_val->ie_pltype) {
      if (sub_ie_val->ie_pltype == AST_EVENT_IE_PLTYPE_EXISTS) {
         /* The subscription only cares that this ie exists. */
         return 1;
      }
      /* Payload types do not match. */
      return 0;
   }

   switch (sub_ie_val->ie_pltype) {
   case AST_EVENT_IE_PLTYPE_UINT:
      res = (sub_ie_val->payload.uint == event_ie_val->payload.uint);
      break;
   case AST_EVENT_IE_PLTYPE_BITFLAGS:
      /*
       * If the subscriber has requested *any* of the bitflags we are providing,
       * then it's a match.
       */
      res = (sub_ie_val->payload.uint & event_ie_val->payload.uint);
      break;
   case AST_EVENT_IE_PLTYPE_STR:
      res = !strcmp(sub_ie_val->payload.str, event_ie_val->payload.str);
      break;
   case AST_EVENT_IE_PLTYPE_RAW:
      res = (sub_ie_val->raw_datalen == event_ie_val->raw_datalen
         && !memcmp(sub_ie_val->payload.raw, event_ie_val->payload.raw,
            sub_ie_val->raw_datalen));
      break;
   case AST_EVENT_IE_PLTYPE_EXISTS:
      /* Should never get here since check_ie_vals cannot have this type. */
      break;
   case AST_EVENT_IE_PLTYPE_UNKNOWN:
      /*
       * Should never be in a subscription event ie val list and
       * check_ie_vals cannot have this type either.
       */
      break;
   }

   return res;
}

enum ast_event_subscriber_res ast_event_check_subscriber(enum ast_event_type type, ...)
{
   va_list ap;
   enum ast_event_ie_type ie_type;
   enum ast_event_subscriber_res res = AST_EVENT_SUB_NONE;
   struct ast_event_ie_val *ie_val;
   struct ast_event_sub *sub;
   struct ast_ev_check_list check_ie_vals = {
      .ie_vals = AST_LIST_HEAD_NOLOCK_INIT_VALUE
   };
   const enum ast_event_type event_types[] = { type, AST_EVENT_ALL };
   int i;
   int want_specific_event;/* TRUE if looking for subscribers wanting specific parameters. */

   if (type >= AST_EVENT_TOTAL) {
      ast_log(LOG_ERROR, "%u is an invalid type!\n", type);
      return res;
   }

   want_specific_event = 0;
   va_start(ap, type);
   for (ie_type = va_arg(ap, enum ast_event_ie_type);
      ie_type != AST_EVENT_IE_END;
      ie_type = va_arg(ap, enum ast_event_ie_type))
   {
      struct ast_event_ie_val *ie_value = alloca(sizeof(*ie_value));
      int insert = 0;

      memset(ie_value, 0, sizeof(*ie_value));
      ie_value->ie_type = ie_type;
      ie_value->ie_pltype = va_arg(ap, enum ast_event_ie_pltype);
      switch (ie_value->ie_pltype) {
      case AST_EVENT_IE_PLTYPE_UINT:
         ie_value->payload.uint = va_arg(ap, uint32_t);
         insert = 1;
         break;
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
         ie_value->payload.uint = va_arg(ap, uint32_t);
         insert = 1;
         break;
      case AST_EVENT_IE_PLTYPE_STR:
         ie_value->payload.str = va_arg(ap, const char *);
         insert = 1;
         break;
      case AST_EVENT_IE_PLTYPE_RAW:
      {
         void *data = va_arg(ap, void *);
         size_t datalen = va_arg(ap, size_t);

         ie_value->payload.raw = alloca(datalen);
         memcpy(ie_value->payload.raw, data, datalen);
         ie_value->raw_datalen = datalen;
         insert = 1;
         break;
      }
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
      case AST_EVENT_IE_PLTYPE_EXISTS:
         /* Unsupported payload type. */
         break;
      }

      if (insert) {
         want_specific_event = 1;
         AST_LIST_INSERT_TAIL(&check_ie_vals.ie_vals, ie_value, entry);
      } else {
         ast_log(LOG_WARNING, "Unsupported PLTYPE(%d)\n", ie_value->ie_pltype);
      }
   }
   va_end(ap);

   for (i = 0; i < ARRAY_LEN(event_types); i++) {
      AST_RWDLLIST_RDLOCK(&ast_event_subs[event_types[i]]);
      if (want_specific_event) {
         AST_RWDLLIST_TRAVERSE(&ast_event_subs[event_types[i]], sub, entry) {
            AST_LIST_TRAVERSE(&sub->ie_vals, ie_val, entry) {
               if (!match_sub_ie_val_to_event(ie_val, &check_ie_vals)) {
                  /* The current subscription ie did not match an event ie. */
                  break;
               }
            }
            if (!ie_val) {
               /* Everything matched.  A subscriber is looking for this event. */
               break;
            }
         }
      } else {
         /* Just looking to see if there are ANY subscribers to the event type. */
         sub = AST_RWLIST_FIRST(&ast_event_subs[event_types[i]]);
      }
      AST_RWDLLIST_UNLOCK(&ast_event_subs[event_types[i]]);
      if (sub) {
         break;
      }
   }

   return sub ? AST_EVENT_SUB_EXISTS : AST_EVENT_SUB_NONE;
}

/*!
 * \internal
 * \brief Check if an ie_val matches an event
 *
 * \param event event to check against
 * \param ie_val IE value to check
 * \param event2 optional event, if specified, the value to compare against will be pulled
 *        from this event instead of from the ie_val structure.  In this case, only the IE
 *        type and payload type will be pulled from ie_val.
 *
 * \retval 0 not matched
 * \retval non-zero matched
 */
static int match_ie_val(const struct ast_event *event,
      const struct ast_event_ie_val *ie_val, const struct ast_event *event2)
{
   switch (ie_val->ie_pltype) {
   case AST_EVENT_IE_PLTYPE_UINT:
   {
      uint32_t val = event2 ? ast_event_get_ie_uint(event2, ie_val->ie_type) : ie_val->payload.uint;

      return (val == ast_event_get_ie_uint(event, ie_val->ie_type)) ? 1 : 0;
   }

   case AST_EVENT_IE_PLTYPE_BITFLAGS:
   {
      uint32_t flags = event2 ? ast_event_get_ie_uint(event2, ie_val->ie_type) : ie_val->payload.uint;

      /*
       * If the subscriber has requested *any* of the bitflags that this event provides,
       * then it's a match.
       */
      return (flags & ast_event_get_ie_bitflags(event, ie_val->ie_type)) ? 1 : 0;
   }

   case AST_EVENT_IE_PLTYPE_STR:
   {
      const char *str;
      uint32_t hash;

      hash = event2 ? ast_event_get_ie_str_hash(event2, ie_val->ie_type) : ie_val->payload.hash;
      if (hash != ast_event_get_ie_str_hash(event, ie_val->ie_type)) {
         return 0;
      }

      str = event2 ? ast_event_get_ie_str(event2, ie_val->ie_type) : ie_val->payload.str;
      if (str && !strcmp(str, ast_event_get_ie_str(event, ie_val->ie_type))) {
         return 1;
      }

      return 0;
   }

   case AST_EVENT_IE_PLTYPE_RAW:
   {
      const void *buf = event2 ? ast_event_get_ie_raw(event2, ie_val->ie_type) : ie_val->payload.raw;
      uint16_t ie_payload_len = event2 ? ast_event_get_ie_raw_payload_len(event2, ie_val->ie_type) : ie_val->raw_datalen;

      return (buf
         && ie_payload_len == ast_event_get_ie_raw_payload_len(event, ie_val->ie_type)
         && !memcmp(buf, ast_event_get_ie_raw(event, ie_val->ie_type), ie_payload_len)) ? 1 : 0;
   }

   case AST_EVENT_IE_PLTYPE_EXISTS:
   {
      return ast_event_get_ie_raw(event, ie_val->ie_type) ? 1 : 0;
   }

   case AST_EVENT_IE_PLTYPE_UNKNOWN:
      return 0;
   }

   return 0;
}

static int dump_cache_cb(void *obj, void *arg, int flags)
{
   const struct ast_event_ref *event_ref = obj;
   const struct ast_event *event = event_ref->event;
   const struct ast_event_sub *event_sub = arg;
   struct ast_event_ie_val *ie_val = NULL;

   AST_LIST_TRAVERSE(&event_sub->ie_vals, ie_val, entry) {
      if (!match_ie_val(event, ie_val, NULL)) {
         break;
      }
   }

   if (!ie_val) {
      /* All parameters were matched on this cache entry, so dump it */
      event_sub->cb(event, event_sub->userdata);
   }

   return 0;
}

/*! \brief Dump the event cache for the subscribed event type */
void ast_event_dump_cache(const struct ast_event_sub *event_sub)
{
   ao2_callback(ast_event_cache[event_sub->type].container, OBJ_NODATA,
         dump_cache_cb, (void *) event_sub);
}

static struct ast_event *gen_sub_event(struct ast_event_sub *sub)
{
   struct ast_event_ie_val *ie_val;
   struct ast_event *event;

   event = ast_event_new(AST_EVENT_SUB,
      AST_EVENT_IE_UNIQUEID,    AST_EVENT_IE_PLTYPE_UINT, sub->uniqueid,
      AST_EVENT_IE_EVENTTYPE,   AST_EVENT_IE_PLTYPE_UINT, sub->type,
      AST_EVENT_IE_DESCRIPTION, AST_EVENT_IE_PLTYPE_STR, sub->description,
      AST_EVENT_IE_END);
   if (!event)
      return NULL;

   AST_LIST_TRAVERSE(&sub->ie_vals, ie_val, entry) {
      switch (ie_val->ie_pltype) {
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
         break;
      case AST_EVENT_IE_PLTYPE_EXISTS:
         ast_event_append_ie_uint(&event, AST_EVENT_IE_EXISTS, ie_val->ie_type);
         break;
      case AST_EVENT_IE_PLTYPE_UINT:
         ast_event_append_ie_uint(&event, ie_val->ie_type, ie_val->payload.uint);
         break;
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
         ast_event_append_ie_bitflags(&event, ie_val->ie_type, ie_val->payload.uint);
         break;
      case AST_EVENT_IE_PLTYPE_STR:
         ast_event_append_ie_str(&event, ie_val->ie_type, ie_val->payload.str);
         break;
      case AST_EVENT_IE_PLTYPE_RAW:
         ast_event_append_ie_raw(&event, ie_val->ie_type, ie_val->payload.raw, ie_val->raw_datalen);
         break;
      }
      if (!event)
         break;
   }

   return event;
}

/*! \brief Send AST_EVENT_SUB events to this subscriber of ... subscriber events */
void ast_event_report_subs(const struct ast_event_sub *event_sub)
{
   struct ast_event *event;
   struct ast_event_sub *sub;
   enum ast_event_type event_type = -1;
   struct ast_event_ie_val *ie_val;

   if (event_sub->type != AST_EVENT_SUB)
      return;

   AST_LIST_TRAVERSE(&event_sub->ie_vals, ie_val, entry) {
      if (ie_val->ie_type == AST_EVENT_IE_EVENTTYPE) {
         event_type = ie_val->payload.uint;
         break;
      }
   }

   if (event_type == -1)
      return;

   AST_RWDLLIST_RDLOCK(&ast_event_subs[event_type]);
   AST_RWDLLIST_TRAVERSE(&ast_event_subs[event_type], sub, entry) {
      if (event_sub == sub) {
         continue;
      }

      event = gen_sub_event(sub);
      if (!event) {
         continue;
      }

      event_sub->cb(event, event_sub->userdata);

      ast_event_destroy(event);
   }
   AST_RWDLLIST_UNLOCK(&ast_event_subs[event_type]);
}

struct ast_event_sub *ast_event_subscribe_new(enum ast_event_type type,
   ast_event_cb_t cb, void *userdata)
{
   struct ast_event_sub *sub;

   if (type < 0 || type >= AST_EVENT_TOTAL) {
      ast_log(LOG_ERROR, "%u is an invalid type!\n", type);
      return NULL;
   }

   if (!(sub = ast_calloc(1, sizeof(*sub)))) {
      return NULL;
   }

   sub->type = type;
   sub->cb = cb;
   sub->userdata = userdata;
   sub->uniqueid = ast_atomic_fetchadd_int((int *) &sub_uniqueid, 1);

   return sub;
}

int ast_event_sub_append_ie_uint(struct ast_event_sub *sub,
   enum ast_event_ie_type ie_type, uint32_t unsigned_int)
{
   struct ast_event_ie_val *ie_val;

   if (ie_type <= 0 || ie_type >= AST_EVENT_IE_TOTAL) {
      return -1;
   }

   if (!(ie_val = ast_calloc(1, sizeof(*ie_val)))) {
      return -1;
   }

   ie_val->ie_type = ie_type;
   ie_val->payload.uint = unsigned_int;
   ie_val->ie_pltype = AST_EVENT_IE_PLTYPE_UINT;

   AST_LIST_INSERT_TAIL(&sub->ie_vals, ie_val, entry);

   return 0;
}

int ast_event_sub_append_ie_bitflags(struct ast_event_sub *sub,
   enum ast_event_ie_type ie_type, uint32_t flags)
{
   struct ast_event_ie_val *ie_val;

   if (ie_type <= 0 || ie_type >= AST_EVENT_IE_TOTAL) {
      return -1;
   }

   if (!(ie_val = ast_calloc(1, sizeof(*ie_val)))) {
      return -1;
   }

   ie_val->ie_type = ie_type;
   ie_val->payload.uint = flags;
   ie_val->ie_pltype = AST_EVENT_IE_PLTYPE_BITFLAGS;

   AST_LIST_INSERT_TAIL(&sub->ie_vals, ie_val, entry);

   return 0;
}

int ast_event_sub_append_ie_exists(struct ast_event_sub *sub,
   enum ast_event_ie_type ie_type)
{
   struct ast_event_ie_val *ie_val;

   if (ie_type <= 0 || ie_type >= AST_EVENT_IE_TOTAL) {
      return -1;
   }

   if (!(ie_val = ast_calloc(1, sizeof(*ie_val)))) {
      return -1;
   }

   ie_val->ie_type = ie_type;
   ie_val->ie_pltype = AST_EVENT_IE_PLTYPE_EXISTS;

   AST_LIST_INSERT_TAIL(&sub->ie_vals, ie_val, entry);

   return 0;
}

int ast_event_sub_append_ie_str(struct ast_event_sub *sub,
   enum ast_event_ie_type ie_type, const char *str)
{
   struct ast_event_ie_val *ie_val;

   if (ie_type <= 0 || ie_type >= AST_EVENT_IE_TOTAL) {
      return -1;
   }

   if (!(ie_val = ast_calloc(1, sizeof(*ie_val)))) {
      return -1;
   }

   ie_val->ie_type = ie_type;
   ie_val->ie_pltype = AST_EVENT_IE_PLTYPE_STR;

   if (!(ie_val->payload.str = ast_strdup(str))) {
      ast_free(ie_val);
      return -1;
   }

   ie_val->payload.hash = ast_str_hash(str);

   AST_LIST_INSERT_TAIL(&sub->ie_vals, ie_val, entry);

   return 0;
}

int ast_event_sub_append_ie_raw(struct ast_event_sub *sub,
   enum ast_event_ie_type ie_type, void *data, size_t raw_datalen)
{
   struct ast_event_ie_val *ie_val;

   if (ie_type <= 0 || ie_type >= AST_EVENT_IE_TOTAL) {
      return -1;
   }

   if (!(ie_val = ast_calloc(1, sizeof(*ie_val)))) {
      return -1;
   }

   ie_val->ie_type = ie_type;
   ie_val->ie_pltype = AST_EVENT_IE_PLTYPE_RAW;
   ie_val->raw_datalen = raw_datalen;

   if (!(ie_val->payload.raw = ast_malloc(raw_datalen))) {
      ast_free(ie_val);
      return -1;
   }

   memcpy(ie_val->payload.raw, data, raw_datalen);

   AST_LIST_INSERT_TAIL(&sub->ie_vals, ie_val, entry);

   return 0;
}

int ast_event_sub_activate(struct ast_event_sub *sub)
{
   if (ast_event_check_subscriber(AST_EVENT_SUB,
      AST_EVENT_IE_EVENTTYPE, AST_EVENT_IE_PLTYPE_UINT, sub->type,
      AST_EVENT_IE_END) != AST_EVENT_SUB_NONE) {
      struct ast_event *event;

      event = gen_sub_event(sub);
      if (event && ast_event_queue(event)) {
         ast_event_destroy(event);
      }
   }

   AST_RWDLLIST_WRLOCK(&ast_event_subs[sub->type]);
   AST_RWDLLIST_INSERT_TAIL(&ast_event_subs[sub->type], sub, entry);
   AST_RWDLLIST_UNLOCK(&ast_event_subs[sub->type]);

   return 0;
}

struct ast_event_sub *ast_event_subscribe(enum ast_event_type type, ast_event_cb_t cb,
   const char *description, void *userdata, ...)
{
   va_list ap;
   enum ast_event_ie_type ie_type;
   struct ast_event_sub *sub;

   if (!(sub = ast_event_subscribe_new(type, cb, userdata))) {
      return NULL;
   }

   ast_copy_string(sub->description, description, sizeof(sub->description));

   va_start(ap, userdata);
   for (ie_type = va_arg(ap, enum ast_event_ie_type);
      ie_type != AST_EVENT_IE_END;
      ie_type = va_arg(ap, enum ast_event_ie_type))
   {
      enum ast_event_ie_pltype ie_pltype;

      ie_pltype = va_arg(ap, enum ast_event_ie_pltype);

      switch (ie_pltype) {
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
         break;
      case AST_EVENT_IE_PLTYPE_UINT:
      {
         uint32_t unsigned_int = va_arg(ap, uint32_t);
         ast_event_sub_append_ie_uint(sub, ie_type, unsigned_int);
         break;
      }
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
      {
         uint32_t unsigned_int = va_arg(ap, uint32_t);
         ast_event_sub_append_ie_bitflags(sub, ie_type, unsigned_int);
         break;
      }
      case AST_EVENT_IE_PLTYPE_STR:
      {
         const char *str = va_arg(ap, const char *);
         ast_event_sub_append_ie_str(sub, ie_type, str);
         break;
      }
      case AST_EVENT_IE_PLTYPE_RAW:
      {
         void *data = va_arg(ap, void *);
         size_t data_len = va_arg(ap, size_t);
         ast_event_sub_append_ie_raw(sub, ie_type, data, data_len);
         break;
      }
      case AST_EVENT_IE_PLTYPE_EXISTS:
         ast_event_sub_append_ie_exists(sub, ie_type);
         break;
      }
   }
   va_end(ap);

   ast_event_sub_activate(sub);

   return sub;
}

void ast_event_sub_destroy(struct ast_event_sub *sub)
{
   struct ast_event_ie_val *ie_val;

   while ((ie_val = AST_LIST_REMOVE_HEAD(&sub->ie_vals, entry))) {
      ast_event_ie_val_destroy(ie_val);
   }

   ast_free(sub);
}

const char *ast_event_subscriber_get_description(struct ast_event_sub *sub)
{
   return sub ? sub->description : NULL;
}

struct ast_event_sub *ast_event_unsubscribe(struct ast_event_sub *sub)
{
   struct ast_event *event;

   AST_RWDLLIST_WRLOCK(&ast_event_subs[sub->type]);
   AST_DLLIST_REMOVE(&ast_event_subs[sub->type], sub, entry);
   AST_RWDLLIST_UNLOCK(&ast_event_subs[sub->type]);

   if (ast_event_check_subscriber(AST_EVENT_UNSUB,
      AST_EVENT_IE_EVENTTYPE, AST_EVENT_IE_PLTYPE_UINT, sub->type,
      AST_EVENT_IE_END) != AST_EVENT_SUB_NONE) {

      event = ast_event_new(AST_EVENT_UNSUB,
         AST_EVENT_IE_UNIQUEID,    AST_EVENT_IE_PLTYPE_UINT, sub->uniqueid,
         AST_EVENT_IE_EVENTTYPE,   AST_EVENT_IE_PLTYPE_UINT, sub->type,
         AST_EVENT_IE_DESCRIPTION, AST_EVENT_IE_PLTYPE_STR, sub->description,
         AST_EVENT_IE_END);
      if (event && ast_event_queue(event)) {
         ast_event_destroy(event);
      }
   }

   ast_event_sub_destroy(sub);

   return NULL;
}

int ast_event_iterator_init(struct ast_event_iterator *iterator, const struct ast_event *event)
{
   int res = 0;

   iterator->event_len = ast_event_get_size(event);
   iterator->event = event;
   if (iterator->event_len >= sizeof(*event) + sizeof(struct ast_event_ie)) {
      iterator->ie = (struct ast_event_ie *) ( ((char *) event) + sizeof(*event) );
   } else {
      iterator->ie = NULL;
      res = -1;
   }

   return res;
}

int ast_event_iterator_next(struct ast_event_iterator *iterator)
{
   iterator->ie = (struct ast_event_ie *) ( ((char *) iterator->ie) + sizeof(*iterator->ie) + ntohs(iterator->ie->ie_payload_len));
   return ((iterator->event_len <= (((char *) iterator->ie) - ((char *) iterator->event))) ? -1 : 0);
}

enum ast_event_ie_type ast_event_iterator_get_ie_type(struct ast_event_iterator *iterator)
{
   return ntohs(iterator->ie->ie_type);
}

uint32_t ast_event_iterator_get_ie_uint(struct ast_event_iterator *iterator)
{
   return ntohl(get_unaligned_uint32(iterator->ie->ie_payload));
}

uint32_t ast_event_iterator_get_ie_bitflags(struct ast_event_iterator *iterator)
{
   return ntohl(get_unaligned_uint32(iterator->ie->ie_payload));
}

const char *ast_event_iterator_get_ie_str(struct ast_event_iterator *iterator)
{
   const struct ast_event_ie_str_payload *str_payload;

   str_payload = (struct ast_event_ie_str_payload *) iterator->ie->ie_payload;

   return str_payload ? str_payload->str : NULL;
}

void *ast_event_iterator_get_ie_raw(struct ast_event_iterator *iterator)
{
   return iterator->ie->ie_payload;
}

uint16_t ast_event_iterator_get_ie_raw_payload_len(struct ast_event_iterator *iterator)
{
   return ntohs(iterator->ie->ie_payload_len);
}

enum ast_event_type ast_event_get_type(const struct ast_event *event)
{
   return ntohs(event->type);
}

uint32_t ast_event_get_ie_uint(const struct ast_event *event, enum ast_event_ie_type ie_type)
{
   const uint32_t *ie_val;

   ie_val = ast_event_get_ie_raw(event, ie_type);

   return ie_val ? ntohl(get_unaligned_uint32(ie_val)) : 0;
}

uint32_t ast_event_get_ie_bitflags(const struct ast_event *event, enum ast_event_ie_type ie_type)
{
   const uint32_t *ie_val;

   ie_val = ast_event_get_ie_raw(event, ie_type);

   return ie_val ? ntohl(get_unaligned_uint32(ie_val)) : 0;
}

uint32_t ast_event_get_ie_str_hash(const struct ast_event *event, enum ast_event_ie_type ie_type)
{
   const struct ast_event_ie_str_payload *str_payload;

   str_payload = ast_event_get_ie_raw(event, ie_type);

   return str_payload ? str_payload->hash : 0;
}

const char *ast_event_get_ie_str(const struct ast_event *event, enum ast_event_ie_type ie_type)
{
   const struct ast_event_ie_str_payload *str_payload;

   str_payload = ast_event_get_ie_raw(event, ie_type);

   return str_payload ? str_payload->str : NULL;
}

const void *ast_event_get_ie_raw(const struct ast_event *event, enum ast_event_ie_type ie_type)
{
   struct ast_event_iterator iterator;
   int res;

   for (res = ast_event_iterator_init(&iterator, event); !res; res = ast_event_iterator_next(&iterator)) {
      if (ast_event_iterator_get_ie_type(&iterator) == ie_type) {
         return ast_event_iterator_get_ie_raw(&iterator);
      }
   }

   return NULL;
}

uint16_t ast_event_get_ie_raw_payload_len(const struct ast_event *event, enum ast_event_ie_type ie_type)
{
   struct ast_event_iterator iterator;
   int res;

   for (res = ast_event_iterator_init(&iterator, event); !res; res = ast_event_iterator_next(&iterator)) {
      if (ast_event_iterator_get_ie_type(&iterator) == ie_type) {
         return ast_event_iterator_get_ie_raw_payload_len(&iterator);
      }
   }

   return 0;
}

int ast_event_append_ie_str(struct ast_event **event, enum ast_event_ie_type ie_type,
   const char *str)
{
   struct ast_event_ie_str_payload *str_payload;
   size_t payload_len;

   payload_len = sizeof(*str_payload) + strlen(str);
   str_payload = alloca(payload_len);

   strcpy(str_payload->str, str);
   str_payload->hash = ast_str_hash(str);

   return ast_event_append_ie_raw(event, ie_type, str_payload, payload_len);
}

int ast_event_append_ie_uint(struct ast_event **event, enum ast_event_ie_type ie_type,
   uint32_t data)
{
   data = htonl(data);
   return ast_event_append_ie_raw(event, ie_type, &data, sizeof(data));
}

int ast_event_append_ie_bitflags(struct ast_event **event, enum ast_event_ie_type ie_type,
   uint32_t flags)
{
   flags = htonl(flags);
   return ast_event_append_ie_raw(event, ie_type, &flags, sizeof(flags));
}

int ast_event_append_ie_raw(struct ast_event **event, enum ast_event_ie_type ie_type,
   const void *data, size_t data_len)
{
   struct ast_event_ie *ie;
   unsigned int extra_len;
   uint16_t event_len;

   event_len = ntohs((*event)->event_len);
   extra_len = sizeof(*ie) + data_len;

   if (!(*event = ast_realloc(*event, event_len + extra_len))) {
      return -1;
   }

   ie = (struct ast_event_ie *) ( ((char *) *event) + event_len );
   ie->ie_type = htons(ie_type);
   ie->ie_payload_len = htons(data_len);
   memcpy(ie->ie_payload, data, data_len);

   (*event)->event_len = htons(event_len + extra_len);

   return 0;
}

struct ast_event *ast_event_new(enum ast_event_type type, ...)
{
   va_list ap;
   struct ast_event *event;
   enum ast_event_ie_type ie_type;
   struct ast_event_ie_val *ie_val;
   int has_ie = 0;
   AST_LIST_HEAD_NOLOCK_STATIC(ie_vals, ast_event_ie_val);

   /* Invalid type */
   if (type >= AST_EVENT_TOTAL) {
      ast_log(LOG_WARNING, "Someone tried to create an event of invalid "
         "type '%d'!\n", type);
      return NULL;
   }

   va_start(ap, type);
   for (ie_type = va_arg(ap, enum ast_event_ie_type);
      ie_type != AST_EVENT_IE_END;
      ie_type = va_arg(ap, enum ast_event_ie_type))
   {
      struct ast_event_ie_val *ie_value = alloca(sizeof(*ie_value));
      int insert = 0;

      memset(ie_value, 0, sizeof(*ie_value));
      ie_value->ie_type = ie_type;
      ie_value->ie_pltype = va_arg(ap, enum ast_event_ie_pltype);
      switch (ie_value->ie_pltype) {
      case AST_EVENT_IE_PLTYPE_UINT:
         ie_value->payload.uint = va_arg(ap, uint32_t);
         insert = 1;
         break;
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
         ie_value->payload.uint = va_arg(ap, uint32_t);
         insert = 1;
         break;
      case AST_EVENT_IE_PLTYPE_STR:
         ie_value->payload.str = va_arg(ap, const char *);
         insert = 1;
         break;
      case AST_EVENT_IE_PLTYPE_RAW:
      {
         void *data = va_arg(ap, void *);
         size_t datalen = va_arg(ap, size_t);
         ie_value->payload.raw = alloca(datalen);
         memcpy(ie_value->payload.raw, data, datalen);
         ie_value->raw_datalen = datalen;
         insert = 1;
         break;
      }
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
      case AST_EVENT_IE_PLTYPE_EXISTS:
         break;
      }

      if (insert) {
         AST_LIST_INSERT_TAIL(&ie_vals, ie_value, entry);
         has_ie = 1;
      } else {
         ast_log(LOG_WARNING, "Unsupported PLTYPE(%d)\n", ie_value->ie_pltype);
      }
   }
   va_end(ap);

   if (!(event = ast_calloc(1, sizeof(*event)))) {
      return NULL;
   }

   event->type = htons(type);
   event->event_len = htons(sizeof(*event));

   AST_LIST_TRAVERSE(&ie_vals, ie_val, entry) {
      switch (ie_val->ie_pltype) {
      case AST_EVENT_IE_PLTYPE_STR:
         ast_event_append_ie_str(&event, ie_val->ie_type, ie_val->payload.str);
         break;
      case AST_EVENT_IE_PLTYPE_UINT:
         ast_event_append_ie_uint(&event, ie_val->ie_type, ie_val->payload.uint);
         break;
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
         ast_event_append_ie_bitflags(&event, ie_val->ie_type, ie_val->payload.uint);
         break;
      case AST_EVENT_IE_PLTYPE_RAW:
         ast_event_append_ie_raw(&event, ie_val->ie_type,
               ie_val->payload.raw, ie_val->raw_datalen);
         break;
      case AST_EVENT_IE_PLTYPE_EXISTS:
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
         break;
      }

      if (!event) {
         break;
      }
   }

   if (has_ie && !ast_event_get_ie_raw(event, AST_EVENT_IE_EID)) {
      /* If the event is originating on this server, add the server's
       * entity ID to the event. */
      ast_event_append_eid(&event);
   }

   return event;
}

int ast_event_append_eid(struct ast_event **event)
{
   return ast_event_append_ie_raw(event, AST_EVENT_IE_EID,
         &ast_eid_default, sizeof(ast_eid_default));
}

void ast_event_destroy(struct ast_event *event)
{
   ast_free(event);
}

static void ast_event_ref_destroy(void *obj)
{
   struct ast_event_ref *event_ref = obj;

   ast_event_destroy(event_ref->event);
}

static struct ast_event *ast_event_dup(const struct ast_event *event)
{
   struct ast_event *dup_event;
   uint16_t event_len;

   event_len = ast_event_get_size(event);

   if (!(dup_event = ast_calloc(1, event_len))) {
      return NULL;
   }

   memcpy(dup_event, event, event_len);

   return dup_event;
}

struct ast_event *ast_event_get_cached(enum ast_event_type type, ...)
{
   va_list ap;
   enum ast_event_ie_type ie_type;
   struct ast_event *dup_event = NULL;
   struct ast_event_ref *cached_event_ref;
   struct ast_event *cache_arg_event;
   struct ast_event_ref tmp_event_ref = {
      .event = NULL,
   };
   struct ao2_container *container = NULL;

   if (type >= AST_EVENT_TOTAL) {
      ast_log(LOG_ERROR, "%u is an invalid type!\n", type);
      return NULL;
   }

   if (!(container = ast_event_cache[type].container)) {
      ast_log(LOG_ERROR, "%u is not a cached event type\n", type);
      return NULL;
   }

   if (!(cache_arg_event = ast_event_new(type, AST_EVENT_IE_END))) {
      return NULL;
   }

   va_start(ap, type);
   for (ie_type = va_arg(ap, enum ast_event_ie_type);
      ie_type != AST_EVENT_IE_END;
      ie_type = va_arg(ap, enum ast_event_ie_type))
   {
      enum ast_event_ie_pltype ie_pltype;

      ie_pltype = va_arg(ap, enum ast_event_ie_pltype);

      switch (ie_pltype) {
      case AST_EVENT_IE_PLTYPE_UINT:
         ast_event_append_ie_uint(&cache_arg_event, ie_type, va_arg(ap, uint32_t));
         break;
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
         ast_event_append_ie_bitflags(&cache_arg_event, ie_type, va_arg(ap, uint32_t));
         break;
      case AST_EVENT_IE_PLTYPE_STR:
         ast_event_append_ie_str(&cache_arg_event, ie_type, va_arg(ap, const char *));
         break;
      case AST_EVENT_IE_PLTYPE_RAW:
      {
         void *data = va_arg(ap, void *);
         size_t datalen = va_arg(ap, size_t);
         ast_event_append_ie_raw(&cache_arg_event, ie_type, data, datalen);
         break;
      }
      case AST_EVENT_IE_PLTYPE_EXISTS:
         ast_log(LOG_WARNING, "PLTYPE_EXISTS not supported by this function\n");
         break;
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
         break;
      }
   }
   va_end(ap);

   tmp_event_ref.event = cache_arg_event;

   cached_event_ref = ao2_find(container, &tmp_event_ref, OBJ_POINTER);

   ast_event_destroy(cache_arg_event);
   cache_arg_event = NULL;

   if (cached_event_ref) {
      dup_event = ast_event_dup(cached_event_ref->event);
      ao2_ref(cached_event_ref, -1);
      cached_event_ref = NULL;
   }

   return dup_event;
}

static struct ast_event_ref *alloc_event_ref(void)
{
   return ao2_alloc(sizeof(struct ast_event_ref), ast_event_ref_destroy);
}

/*!
 * \internal
 * \brief Update the given event cache with the new event.
 * \since 1.8
 *
 * \param cache Event cache container to update.
 * \param event New event to put in the cache.
 *
 * \return Nothing
 */
static void event_update_cache(struct ao2_container *cache, struct ast_event *event)
{
   struct ast_event_ref tmp_event_ref = {
      .event = event,
   };
   struct ast_event *dup_event;
   struct ast_event_ref *event_ref;

   /* Hold the cache container lock while it is updated. */
   ao2_lock(cache);

   /* Remove matches from the cache. */
   ao2_callback(cache, OBJ_POINTER | OBJ_UNLINK | OBJ_MULTIPLE | OBJ_NODATA,
      ast_event_cmp, &tmp_event_ref);

   /* Save a copy of the event in the cache. */
   dup_event = ast_event_dup(event);
   if (dup_event) {
      event_ref = alloc_event_ref();
      if (event_ref) {
         event_ref->event = dup_event;
         ao2_link(cache, event_ref);
         ao2_ref(event_ref, -1);
      } else {
         ast_event_destroy(dup_event);
      }
   }

   ao2_unlock(cache);
}

int ast_event_queue_and_cache(struct ast_event *event)
{
   struct ao2_container *container;

   container = ast_event_cache[ast_event_get_type(event)].container;
   if (!container) {
      ast_log(LOG_WARNING, "cache requested for non-cached event type\n");
   } else {
      event_update_cache(container, event);
   }

   if (ast_event_queue(event)) {
      ast_event_destroy(event);
   }
   return 0;
}

static int handle_event(void *data)
{
   struct ast_event_ref *event_ref = data;
   struct ast_event_sub *sub;
   const enum ast_event_type event_types[] = {
      ntohs(event_ref->event->type),
      AST_EVENT_ALL
   };
   int i;

   for (i = 0; i < ARRAY_LEN(event_types); i++) {
      AST_RWDLLIST_RDLOCK(&ast_event_subs[event_types[i]]);
      AST_RWDLLIST_TRAVERSE(&ast_event_subs[event_types[i]], sub, entry) {
         struct ast_event_ie_val *ie_val;

         AST_LIST_TRAVERSE(&sub->ie_vals, ie_val, entry) {
            if (!match_ie_val(event_ref->event, ie_val, NULL)) {
               /* The current subscription ie did not match an event ie. */
               break;
            }
         }
         if (ie_val) {
            /* The event did not match this subscription. */
            continue;
         }
         sub->cb(event_ref->event, sub->userdata);
      }
      AST_RWDLLIST_UNLOCK(&ast_event_subs[event_types[i]]);
   }

   ao2_ref(event_ref, -1);

   return 0;
}

int ast_event_queue(struct ast_event *event)
{
   struct ast_event_ref *event_ref;
   uint16_t host_event_type;
   int res;

   host_event_type = ntohs(event->type);

   /* Invalid type */
   if (host_event_type >= AST_EVENT_TOTAL) {
      ast_log(LOG_WARNING, "Someone tried to queue an event of invalid "
         "type '%d'!\n", host_event_type);
      return -1;
   }

   /* If nobody has subscribed to this event type, throw it away now */
   if (ast_event_check_subscriber(host_event_type, AST_EVENT_IE_END)
         == AST_EVENT_SUB_NONE) {
      ast_event_destroy(event);
      return 0;
   }

   if (!(event_ref = alloc_event_ref())) {
      return -1;
   }

   event_ref->event = event;

   res = ast_taskprocessor_push(event_dispatcher, handle_event, event_ref);
   if (res) {
      event_ref->event = NULL;
      ao2_ref(event_ref, -1);
   }
   return res;
}

static int ast_event_hash_mwi(const void *obj, const int flags)
{
   const struct ast_event *event = obj;
   const char *mailbox = ast_event_get_ie_str(event, AST_EVENT_IE_MAILBOX);
   const char *context = ast_event_get_ie_str(event, AST_EVENT_IE_CONTEXT);

   return ast_str_hash_add(context, ast_str_hash(mailbox));
}

/*!
 * \internal
 * \brief Hash function for AST_EVENT_DEVICE_STATE
 *
 * \param[in] obj an ast_event
 * \param[in] flags unused
 *
 * \return hash value
 */
static int ast_event_hash_devstate(const void *obj, const int flags)
{
   const struct ast_event *event = obj;

   return ast_str_hash(ast_event_get_ie_str(event, AST_EVENT_IE_DEVICE));
}

/*!
 * \internal
 * \brief Hash function for AST_EVENT_DEVICE_STATE_CHANGE
 *
 * \param[in] obj an ast_event
 * \param[in] flags unused
 *
 * \return hash value
 */
static int ast_event_hash_devstate_change(const void *obj, const int flags)
{
   const struct ast_event *event = obj;

   return ast_str_hash(ast_event_get_ie_str(event, AST_EVENT_IE_DEVICE));
}

static int ast_event_hash(const void *obj, const int flags)
{
   const struct ast_event_ref *event_ref;
   const struct ast_event *event;
   ao2_hash_fn *hash_fn;

   event_ref = obj;
   event = event_ref->event;

   if (!(hash_fn = ast_event_cache[ast_event_get_type(event)].hash_fn)) {
      return 0;
   }

   return hash_fn(event, flags);
}

/*!
 * \internal
 * \brief Compare two events
 *
 * \param[in] obj the first event, as an ast_event_ref
 * \param[in] arg the second event, as an ast_event_ref
 * \param[in] flags unused
 *
 * \pre Both events must be the same type.
 * \pre The event type must be declared as a cached event type in ast_event_cache
 *
 * \details This function takes two events, and determines if they are considered
 * equivalent.  The values of information elements specified in the cache arguments
 * for the event type are used to determine if the events are equivalent.
 *
 * \retval 0 No match
 * \retval CMP_MATCH The events are considered equivalent based on the cache arguments
 */
static int ast_event_cmp(void *obj, void *arg, int flags)
{
   struct ast_event_ref *event_ref, *event_ref2;
   struct ast_event *event, *event2;
   int res = CMP_MATCH;
   int i;
   enum ast_event_ie_type *cache_args;

   event_ref = obj;
   event = event_ref->event;

   event_ref2 = arg;
   event2 = event_ref2->event;

   cache_args = ast_event_cache[ast_event_get_type(event)].cache_args;

   for (i = 0; i < ARRAY_LEN(ast_event_cache[0].cache_args) && cache_args[i]; i++) {
      struct ast_event_ie_val ie_val = {
         .ie_pltype = ast_event_get_ie_pltype(cache_args[i]),
         .ie_type = cache_args[i],
      };

      if (!match_ie_val(event, &ie_val, event2)) {
         res = 0;
         break;
      }
   }

   return res;
}

static void dump_raw_ie(struct ast_event_iterator *i, struct ast_cli_args *a)
{
   char eid_buf[32];
   enum ast_event_ie_type ie_type;
   const char *ie_type_name;

   ie_type = ast_event_iterator_get_ie_type(i);
   ie_type_name = ast_event_get_ie_type_name(ie_type);

   switch (ie_type) {
   case AST_EVENT_IE_EID:
      ast_eid_to_str(eid_buf, sizeof(eid_buf), ast_event_iterator_get_ie_raw(i));
      ast_cli(a->fd, "%.30s: %s\n", ie_type_name, eid_buf);
      break;
   default:
      ast_cli(a->fd, "%s\n", ie_type_name);
      break;
   }
}

static int event_dump_cli(void *obj, void *arg, int flags)
{
   const struct ast_event_ref *event_ref = obj;
   const struct ast_event *event = event_ref->event;
   struct ast_cli_args *a = arg;
   struct ast_event_iterator i;

   if (ast_event_iterator_init(&i, event)) {
      ast_cli(a->fd, "Failed to initialize event iterator.  :-(\n");
      return 0;
   }

   ast_cli(a->fd, "Event: %s\n", ast_event_get_type_name(event));

   do {
      enum ast_event_ie_type ie_type;
      enum ast_event_ie_pltype ie_pltype;
      const char *ie_type_name;

      ie_type = ast_event_iterator_get_ie_type(&i);
      ie_type_name = ast_event_get_ie_type_name(ie_type);
      ie_pltype = ast_event_get_ie_pltype(ie_type);

      switch (ie_pltype) {
      case AST_EVENT_IE_PLTYPE_UNKNOWN:
      case AST_EVENT_IE_PLTYPE_EXISTS:
         ast_cli(a->fd, "%s\n", ie_type_name);
         break;
      case AST_EVENT_IE_PLTYPE_STR:
         ast_cli(a->fd, "%.30s: %s\n", ie_type_name,
               ast_event_iterator_get_ie_str(&i));
         break;
      case AST_EVENT_IE_PLTYPE_UINT:
         ast_cli(a->fd, "%.30s: %u\n", ie_type_name,
               ast_event_iterator_get_ie_uint(&i));
         break;
      case AST_EVENT_IE_PLTYPE_BITFLAGS:
         ast_cli(a->fd, "%.30s: %u\n", ie_type_name,
               ast_event_iterator_get_ie_bitflags(&i));
         break;
      case AST_EVENT_IE_PLTYPE_RAW:
         dump_raw_ie(&i, a);
         break;
      }
   } while (!ast_event_iterator_next(&i));

   ast_cli(a->fd, "\n");

   return 0;
}

static char *event_dump_cache(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   enum ast_event_type event_type;
   enum ast_event_ie_type *cache_args;
   int i;

   switch (cmd) {
   case CLI_INIT:
      e->command = "event dump cache";
      e->usage =
         "Usage: event dump cache <event type>\n"
         "       Dump all of the cached events for the given event type.\n"
         "       This is primarily intended for debugging.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos == 3) {
         return ast_cli_complete(a->word, cached_event_types, a->n);
      }
      return NULL;
   case CLI_HANDLER:
      break;
   }

   if (a->argc != e->args + 1) {
      return CLI_SHOWUSAGE;
   }

   if (ast_event_str_to_event_type(a->argv[e->args], &event_type)) {
      ast_cli(a->fd, "Invalid cached event type: '%s'\n", a->argv[e->args]);
      return CLI_SHOWUSAGE;
   }

   if (!ast_event_cache[event_type].container) {
      ast_cli(a->fd, "Event type '%s' has no cache.\n", a->argv[e->args]);
      return CLI_SUCCESS;
   }

   ast_cli(a->fd, "Event Type: %s\n", a->argv[e->args]);
   ast_cli(a->fd, "Cache Unique Keys:\n");
   cache_args = ast_event_cache[event_type].cache_args;
   for (i = 0; i < ARRAY_LEN(ast_event_cache[0].cache_args) && cache_args[i]; i++) {
      ast_cli(a->fd, "--> %s\n", ast_event_get_ie_type_name(cache_args[i]));
   }

   ast_cli(a->fd, "\n--- Begin Cache Dump ---\n\n");
   ao2_callback(ast_event_cache[event_type].container, OBJ_NODATA, event_dump_cli, a);
   ast_cli(a->fd, "--- End Cache Dump ---\n\n");

   return CLI_SUCCESS;
}

static struct ast_cli_entry event_cli[] = {
   AST_CLI_DEFINE(event_dump_cache, "Dump the internal event cache (for debugging)"),
};

int ast_event_init(void)
{
   int i;

   for (i = 0; i < AST_EVENT_TOTAL; i++) {
      AST_RWDLLIST_HEAD_INIT(&ast_event_subs[i]);
   }

   for (i = 0; i < AST_EVENT_TOTAL; i++) {
      if (!ast_event_cache[i].hash_fn) {
         /* This event type is not cached. */
         continue;
      }

      if (!(ast_event_cache[i].container = ao2_container_alloc(NUM_CACHE_BUCKETS,
            ast_event_hash, ast_event_cmp))) {
         return -1;
      }
   }

   if (!(event_dispatcher = ast_taskprocessor_get("core_event_dispatcher", 0))) {
      return -1;
   }

   ast_cli_register_multiple(event_cli, ARRAY_LEN(event_cli));

   return 0;
}

size_t ast_event_minimum_length(void)
{
   return sizeof(struct ast_event);
}