ARI: Add the ability to intercept hold and raise an event

For some applications - such as SLA - a phone pressing hold should not behave
in the fashion that the Asterisk core would like it to. Instead, the hold
action has some application specific behaviour associated with it - such as
disconnecting the channel that initiated the hold; only playing MoH to channels
in the bridge if the channels are of a particular type, etc.

One way of accomplishing this is to use a framehook to intercept the
hold/unhold frames, raise an event, and eat the frame. Tasty. This patch
accomplishes that using a new dialplan function, HOLD_INTERCEPT.

In addition, some general cleanup of raising hold/unhold Stasis messages was
done, including removing some RAII_VAR usage.

Review: https://reviewboard.asterisk.org/r/4549/

ASTERISK-24922 #close
........

Merged revisions 434216 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@434217 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/ari/ari_model_validators.h

@@ -808,6 +808,24 @@ int ast_ari_validate_channel_hangup_request(struct ast_json *json);
  */
 ari_validator ast_ari_validate_channel_hangup_request_fn(void);
 
+/*!
+ * \brief Validator for ChannelHold.
+ *
+ * A channel initiated a media hold.
+ *
+ * \param json JSON object to validate.
+ * \returns True (non-zero) if valid.
+ * \returns False (zero) if invalid.
+ */
+int ast_ari_validate_channel_hold(struct ast_json *json);
+
+/*!
+ * \brief Function pointer to ast_ari_validate_channel_hold().
+ *
+ * See \ref ast_ari_model_validators.h for more details.
+ */
+ari_validator ast_ari_validate_channel_hold_fn(void);
+
 /*!
  * \brief Validator for ChannelLeftBridge.
  *
@@ -880,6 +898,24 @@ int ast_ari_validate_channel_talking_started(struct ast_json *json);
  */
 ari_validator ast_ari_validate_channel_talking_started_fn(void);
 
+/*!
+ * \brief Validator for ChannelUnhold.
+ *
+ * A channel initiated a media unhold.
+ *
+ * \param json JSON object to validate.
+ * \returns True (non-zero) if valid.
+ * \returns False (zero) if invalid.
+ */
+int ast_ari_validate_channel_unhold(struct ast_json *json);
+
+/*!
+ * \brief Function pointer to ast_ari_validate_channel_unhold().
+ *
+ * See \ref ast_ari_model_validators.h for more details.
+ */
+ari_validator ast_ari_validate_channel_unhold_fn(void);
+
 /*!
  * \brief Validator for ChannelUserevent.
  *
@@ -1393,6 +1429,11 @@ ari_validator ast_ari_validate_application_fn(void);
  * - cause: int
  * - channel: Channel (required)
  * - soft: boolean
+ * ChannelHold
+ * - type: string (required)
+ * - application: string (required)
+ * - timestamp: Date
+ * - channel: Channel (required)
  * ChannelLeftBridge
  * - type: string (required)
  * - application: string (required)
@@ -1415,6 +1456,11 @@ ari_validator ast_ari_validate_application_fn(void);
  * - application: string (required)
  * - timestamp: Date
  * - channel: Channel (required)
+ * ChannelUnhold
+ * - type: string (required)
+ * - application: string (required)
+ * - timestamp: Date
+ * - channel: Channel (required)
  * ChannelUserevent
  * - type: string (required)
  * - application: string (required)