No response sent for SIP CC subscribe/resubscribe request.

Asterisk does not send a response if we try to subscribe for call
completion after we have received a 180 Ringing.  You can only subscribe
for call completion when the call has been cleared.

When we receive the 180 Ringing, for this call, its call-completion state
is 'CC_AVAILABLE'.  If we then send a subscribe message to Asterisk, it
trys to change the call-completion state to 'CC_CALLER_REQUESTED'.
Because this is an invalid state change, it just ignores the message.  The
only state Asterisk will accept our subscribe message is in the
'CC_CALLER_OFFERED' state.

Asterisk will go into the 'CC_CALLER_OFFERED' when the SIP client clears
the call by sending a CANCEL.

Asterisk should always send a response.  Even if its a negative one.


The fix is to allow for the CCSS core to notify a CC agent that a failure
has occurred when CC is requested.  The "ack" callback is replaced with a
"respond" callback.  The "respond" callback has a parameter indicating
either a successful response or a specific type of failure that may need
to be communicated to the requester.

(closes issue #18336)
Reported by: GeorgeKonopacki
Tested by: mmichelson, rmudgett

JIRA SWP-2633

(closes issue #18337)
Reported by: GeorgeKonopacki
Tested by: mmichelson

JIRA SWP-2634


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.8@307879 f38db490-d61c-443f-a65b-d21fe96a405b

channels/chan_dahdi.c

@@ -16115,7 +16115,7 @@ static struct ast_cc_agent_callbacks dahdi_pri_cc_agent_callbacks = {
 	.init = dahdi_pri_cc_agent_init,
 	.start_offer_timer = sig_pri_cc_agent_start_offer_timer,
 	.stop_offer_timer = sig_pri_cc_agent_stop_offer_timer,
-	.ack = sig_pri_cc_agent_req_ack,
+	.respond = sig_pri_cc_agent_req_rsp,
 	.status_request = sig_pri_cc_agent_status_req,
 	.stop_ringing = sig_pri_cc_agent_stop_ringing,
 	.party_b_free = sig_pri_cc_agent_party_b_free,

channels/chan_sip.c

@@ -1601,7 +1601,7 @@ struct ast_channel_tech sip_tech_info;
 static int sip_cc_agent_init(struct ast_cc_agent *agent, struct ast_channel *chan);
 static int sip_cc_agent_start_offer_timer(struct ast_cc_agent *agent);
 static int sip_cc_agent_stop_offer_timer(struct ast_cc_agent *agent);
-static void sip_cc_agent_ack(struct ast_cc_agent *agent);
+static void sip_cc_agent_respond(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason);
 static int sip_cc_agent_status_request(struct ast_cc_agent *agent);
 static int sip_cc_agent_start_monitoring(struct ast_cc_agent *agent);
 static int sip_cc_agent_recall(struct ast_cc_agent *agent);
@@ -1612,7 +1612,7 @@ static struct ast_cc_agent_callbacks sip_cc_agent_callbacks = {
 	.init = sip_cc_agent_init,
 	.start_offer_timer = sip_cc_agent_start_offer_timer,
 	.stop_offer_timer = sip_cc_agent_stop_offer_timer,
-	.ack = sip_cc_agent_ack,
+	.respond = sip_cc_agent_respond,
 	.status_request = sip_cc_agent_status_request,
 	.start_monitoring = sip_cc_agent_start_monitoring,
 	.callee_available = sip_cc_agent_recall,
@@ -1713,14 +1713,30 @@ static int sip_cc_agent_stop_offer_timer(struct ast_cc_agent *agent)
 	return 0;
 }
 
-static void sip_cc_agent_ack(struct ast_cc_agent *agent)
+static void sip_cc_agent_respond(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason)
 {
 	struct sip_cc_agent_pvt *agent_pvt = agent->private_data;
 
 	sip_pvt_lock(agent_pvt->subscribe_pvt);
 	ast_set_flag(&agent_pvt->subscribe_pvt->flags[1], SIP_PAGE2_DIALOG_ESTABLISHED);
-	transmit_response(agent_pvt->subscribe_pvt, "200 OK", &agent_pvt->subscribe_pvt->initreq);
-	transmit_cc_notify(agent, agent_pvt->subscribe_pvt, CC_QUEUED);
+	if (reason == AST_CC_AGENT_RESPONSE_SUCCESS || !ast_strlen_zero(agent_pvt->notify_uri)) {
+		/* The second half of this if statement may be a bit hard to grasp,
+		 * so here's an explanation. When a subscription comes into
+		 * chan_sip, as long as it is not malformed, it will be passed
+		 * to the CC core. If the core senses an out-of-order state transition,
+		 * then the core will call this callback with the "reason" set to a
+		 * failure condition.
+		 * However, an out-of-order state transition will occur during a resubscription
+		 * for CC. In such a case, we can see that we have already generated a notify_uri
+		 * and so we can detect that this isn't a *real* failure. Rather, it is just
+		 * something the core doesn't recognize as a legitimate SIP state transition.
+		 * Thus we respond with happiness and flowers.
+		 */
+		transmit_response(agent_pvt->subscribe_pvt, "200 OK", &agent_pvt->subscribe_pvt->initreq);
+		transmit_cc_notify(agent, agent_pvt->subscribe_pvt, CC_QUEUED);
+	} else {
+		transmit_response(agent_pvt->subscribe_pvt, "500 Internal Error", &agent_pvt->subscribe_pvt->initreq);
+	}
 	sip_pvt_unlock(agent_pvt->subscribe_pvt);
 	agent_pvt->is_available = TRUE;
 }

channels/sig_pri.c

@@ -7563,38 +7563,75 @@ int sig_pri_cc_agent_stop_offer_timer(struct ast_cc_agent *agent)
 
 #if defined(HAVE_PRI_CCSS)
 /*!
- * \brief Acknowledge CC request.
+ * \brief Response to a CC request.
  * \since 1.8
  *
  * \param agent CC core agent control.
+ * \param reason CC request response status.
  *
  * \details
  * When the core receives knowledge that a called
  * party has accepted a CC request, it will call
- * this callback.
+ * this callback.  The core may also call this
+ * if there is some error when attempting to process
+ * the incoming CC request.
  *
- * The duty of this is to accept a CC request from
- * the caller by acknowledging receipt of that request.
+ * The duty of this is to issue a propper response to a
+ * CC request from the caller by acknowledging receipt
+ * of that request or rejecting it.
  *
  * \return Nothing
  */
-void sig_pri_cc_agent_req_ack(struct ast_cc_agent *agent)
+void sig_pri_cc_agent_req_rsp(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason)
 {
 	struct sig_pri_cc_agent_prv *cc_pvt;
 	int res;
+	int status;
+	const char *failed_msg;
+	static const char *failed_to_send = "Failed to send the CC request response.";
+	static const char *not_accepted = "The core declined the CC request.";
 
 	cc_pvt = agent->private_data;
 	ast_mutex_lock(&cc_pvt->pri->lock);
 	if (cc_pvt->cc_request_response_pending) {
 		cc_pvt->cc_request_response_pending = 0;
-		res = pri_cc_req_rsp(cc_pvt->pri->pri, cc_pvt->cc_id, 0/* success */);
+
+		/* Convert core response reason to ISDN response status. */
+		status = 2;/* short_term_denial */
+		switch (reason) {
+		case AST_CC_AGENT_RESPONSE_SUCCESS:
+			status = 0;/* success */
+			break;
+		case AST_CC_AGENT_RESPONSE_FAILURE_INVALID:
+			status = 2;/* short_term_denial */
+			break;
+		case AST_CC_AGENT_RESPONSE_FAILURE_TOO_MANY:
+			status = 5;/* queue_full */
+			break;
+		}
+
+		res = pri_cc_req_rsp(cc_pvt->pri->pri, cc_pvt->cc_id, status);
+		if (!status) {
+			/* CC core request was accepted. */
+			if (res) {
+				failed_msg = failed_to_send;
+			} else {
+				failed_msg = NULL;
+			}
+		} else {
+			/* CC core request was declined. */
+			if (res) {
+				failed_msg = failed_to_send;
+			} else {
+				failed_msg = not_accepted;
+			}
+		}
 	} else {
-		res = 0;
+		failed_msg = NULL;
 	}
 	ast_mutex_unlock(&cc_pvt->pri->lock);
-	if (res) {
-		ast_cc_failed(agent->core_id, "%s agent failed to send the CC request ack.",
-			sig_pri_cc_type_name);
+	if (failed_msg) {
+		ast_cc_failed(agent->core_id, "%s agent: %s", sig_pri_cc_type_name, failed_msg);
 	}
 }
 #endif	/* defined(HAVE_PRI_CCSS) */

channels/sig_pri.h

@@ -514,7 +514,7 @@ void sig_pri_fixup(struct ast_channel *oldchan, struct ast_channel *newchan, str
 int sig_pri_cc_agent_init(struct ast_cc_agent *agent, struct sig_pri_chan *pvt_chan);
 int sig_pri_cc_agent_start_offer_timer(struct ast_cc_agent *agent);
 int sig_pri_cc_agent_stop_offer_timer(struct ast_cc_agent *agent);
-void sig_pri_cc_agent_req_ack(struct ast_cc_agent *agent);
+void sig_pri_cc_agent_req_rsp(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason);
 int sig_pri_cc_agent_status_req(struct ast_cc_agent *agent);
 int sig_pri_cc_agent_stop_ringing(struct ast_cc_agent *agent);
 int sig_pri_cc_agent_party_b_free(struct ast_cc_agent *agent);

include/asterisk/ccss.h

@@ -858,6 +858,15 @@ struct ast_cc_agent {
 	char device_name[1];
 };
 
+enum ast_cc_agent_response_reason {
+	/*! CC request accepted */
+	AST_CC_AGENT_RESPONSE_SUCCESS,
+	/*! CC request not allowed at this time. Invalid state transition. */
+	AST_CC_AGENT_RESPONSE_FAILURE_INVALID,
+	/*! Too many CC requests in the system. */
+	AST_CC_AGENT_RESPONSE_FAILURE_TOO_MANY,
+};
+
 struct ast_cc_agent_callbacks {
 	/*!
 	 * \brief Type of agent the callbacks belong to.
@@ -920,19 +929,23 @@ struct ast_cc_agent_callbacks {
 	 */
 	int (*stop_offer_timer)(struct ast_cc_agent *agent);
 	/*!
-	 * \brief Acknowledge CC request.
+	 * \brief Respond to a CC request.
 	 *
 	 * \param agent CC core agent control.
+	 * \param reason CC request response status.
 	 *
 	 * \details
 	 * When the core receives knowledge that a called
 	 * party has accepted a CC request, it will call
-	 * this callback.
+	 * this callback. The core may also call this
+	 * if there is some error when attempting to process
+	 * the incoming CC request.
 	 *
-	 * The duty of this is to accept a CC request from
-	 * the caller by acknowledging receipt of that request.
+	 * The duty of this is to issue a propper response to a
+	 * CC request from the caller by acknowledging receipt
+	 * of that request or rejecting it.
 	 */
-	void (*ack)(struct ast_cc_agent *agent);
+	void (*respond)(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason);
 	/*!
 	 * \brief Request the status of the agent's device.
 	 *

main/ccss.c

@@ -2205,7 +2205,7 @@ static void check_callback_sanity(const struct ast_cc_agent_callbacks *callbacks
 	ast_assert(callbacks->init != NULL);
 	ast_assert(callbacks->start_offer_timer != NULL);
 	ast_assert(callbacks->stop_offer_timer != NULL);
-	ast_assert(callbacks->ack != NULL);
+	ast_assert(callbacks->respond != NULL);
 	ast_assert(callbacks->status_request != NULL);
 	ast_assert(callbacks->start_monitoring != NULL);
 	ast_assert(callbacks->callee_available != NULL);
@@ -2267,7 +2267,7 @@ static struct ast_cc_agent *cc_agent_init(struct ast_channel *caller_chan,
 static int cc_generic_agent_init(struct ast_cc_agent *agent, struct ast_channel *chan);
 static int cc_generic_agent_start_offer_timer(struct ast_cc_agent *agent);
 static int cc_generic_agent_stop_offer_timer(struct ast_cc_agent *agent);
-static void cc_generic_agent_ack(struct ast_cc_agent *agent);
+static void cc_generic_agent_respond(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason);
 static int cc_generic_agent_status_request(struct ast_cc_agent *agent);
 static int cc_generic_agent_stop_ringing(struct ast_cc_agent *agent);
 static int cc_generic_agent_start_monitoring(struct ast_cc_agent *agent);
@@ -2279,7 +2279,7 @@ static struct ast_cc_agent_callbacks generic_agent_callbacks = {
 	.init = cc_generic_agent_init,
 	.start_offer_timer = cc_generic_agent_start_offer_timer,
 	.stop_offer_timer = cc_generic_agent_stop_offer_timer,
-	.ack = cc_generic_agent_ack,
+	.respond = cc_generic_agent_respond,
 	.status_request = cc_generic_agent_status_request,
 	.stop_ringing = cc_generic_agent_stop_ringing,
 	.start_monitoring = cc_generic_agent_start_monitoring,
@@ -2403,7 +2403,7 @@ static int cc_generic_agent_stop_offer_timer(struct ast_cc_agent *agent)
 	return 0;
 }
 
-static void cc_generic_agent_ack(struct ast_cc_agent *agent)
+static void cc_generic_agent_respond(struct ast_cc_agent *agent, enum ast_cc_agent_response_reason reason)
 {
 	/* The generic agent doesn't have to do anything special to
 	 * acknowledge a CC request. Just return.
@@ -2625,6 +2625,7 @@ static struct cc_core_instance *cc_core_init_instance(struct ast_channel *caller
 }
 
 struct cc_state_change_args {
+	struct cc_core_instance *core_instance;/*!< Holds reference to core instance. */
 	enum cc_state state;
 	int core_id;
 	char debug[1];
@@ -2773,6 +2774,8 @@ static int cc_caller_requested(struct cc_core_instance *core_instance, struct cc
 {
 	if (!ast_cc_request_is_within_limits()) {
 		ast_log(LOG_WARNING, "Cannot request CC since there is no more room for requests\n");
+		core_instance->agent->callbacks->respond(core_instance->agent,
+			AST_CC_AGENT_RESPONSE_FAILURE_TOO_MANY);
 		ast_cc_failed(core_instance->core_id, "Too many requests in the system");
 		return -1;
 	}
@@ -2811,7 +2814,8 @@ static int cc_active(struct cc_core_instance *core_instance, struct cc_state_cha
 	 *    call monitor's unsuspend callback.
 	 */
 	if (previous_state == CC_CALLER_REQUESTED) {
-		core_instance->agent->callbacks->ack(core_instance->agent);
+		core_instance->agent->callbacks->respond(core_instance->agent,
+			AST_CC_AGENT_RESPONSE_SUCCESS);
 		manager_event(EVENT_FLAG_CC, "CCRequestAcknowledged",
 			"CoreID: %d\r\n"
 			"Caller: %s\r\n",
@@ -2948,15 +2952,19 @@ static int cc_do_state_change(void *datap)
 	ast_log_dynamic_level(cc_logger_level, "Core %d: State change to %d requested. Reason: %s\n",
 			args->core_id, args->state, args->debug);
 
-	if (!(core_instance = find_cc_core_instance(args->core_id))) {
-		ast_log_dynamic_level(cc_logger_level, "Core %d: Unable to find core instance.\n", args->core_id);
-		ast_free(args);
-		return -1;
-	}
+	core_instance = args->core_instance;
 
 	if (!is_state_change_valid(core_instance->current_state, args->state, core_instance->agent)) {
 		ast_log_dynamic_level(cc_logger_level, "Core %d: Invalid state change requested. Cannot go from %s to %s\n",
 				args->core_id, cc_state_to_string(core_instance->current_state), cc_state_to_string(args->state));
+		if (args->state == CC_CALLER_REQUESTED) {
+			/*
+			 * For out-of-order requests, we need to let the requester know that
+			 * we can't handle the request now.
+			 */
+			core_instance->agent->callbacks->respond(core_instance->agent,
+				AST_CC_AGENT_RESPONSE_FAILURE_INVALID);
+		}
 		ast_free(args);
 		cc_unref(core_instance, "Unref core instance from when it was found earlier");
 		return -1;
@@ -2978,6 +2986,7 @@ static int cc_request_state_change(enum cc_state state, const int core_id, const
 	int debuglen;
 	char dummy[1];
 	va_list aq;
+	struct cc_core_instance *core_instance;
 	struct cc_state_change_args *args;
 	/* This initial call to vsnprintf is simply to find what the
 	 * size of the string needs to be
@@ -2993,12 +3002,22 @@ static int cc_request_state_change(enum cc_state state, const int core_id, const
 		return -1;
 	}
 
+	core_instance = find_cc_core_instance(core_id);
+	if (!core_instance) {
+		ast_log_dynamic_level(cc_logger_level, "Core %d: Unable to find core instance.\n",
+			core_id);
+		ast_free(args);
+		return -1;
+	}
+
+	args->core_instance = core_instance;
 	args->state = state;
 	args->core_id = core_id;
 	vsnprintf(args->debug, debuglen, debug, ap);
 
 	res = ast_taskprocessor_push(cc_core_taskprocessor, cc_do_state_change, args);
 	if (res) {
+		cc_unref(core_instance, "Unref core instance. ast_taskprocessor_push failed");
 		ast_free(args);
 	}
 	return res;