chan_pjsip: Add ability to send flash events.

PJSIP currently is capable of receiving flash events
and converting them to FLASH control frames, but it
currently lacks support for doing the reverse: taking
a FLASH control frame and converting it into a flash
event in the SIP domain.

This adds the ability for PJSIP to process flash control
frames by converting them into the appropriate SIP INFO
message, which can then be sent to the peer. This allows,
for example, flash events to be sent between Asterisk
systems using PJSIP.

ASTERISK-29941 #close

Change-Id: I1590221a4d238597f79672fa5825dd4a920c94dd

channels/chan_pjsip.c

@@ -1601,6 +1601,10 @@ static int handle_topology_request_change(struct ast_sip_session *session,
 	SCOPE_EXIT_RTN_VALUE(res, "RC: %d\n", res);
 }
 
+/* Forward declarations */
+static int transmit_info_dtmf(void *data);
+static struct info_dtmf_data *info_dtmf_data_alloc(struct ast_sip_session *session, char digit, unsigned int duration);
+
 /*! \brief Function called by core to ask the channel to indicate some sort of condition */
 static int chan_pjsip_indicate(struct ast_channel *ast, int condition, const void *data, size_t datalen)
 {
@@ -1621,6 +1625,10 @@ static int chan_pjsip_indicate(struct ast_channel *ast, int condition, const voi
 		.data.ptr = (void *)data,
 	};
 	char condition_name[256];
+	unsigned int duration;
+	char digit;
+	struct info_dtmf_data *dtmf_data;
+
 	SCOPE_ENTER(3, "%s: Indicated %s\n", ast_channel_name(ast),
 		ast_frame_subclass2str(&f, condition_name, sizeof(condition_name), NULL, 0));
 
@@ -1680,6 +1688,22 @@ static int chan_pjsip_indicate(struct ast_channel *ast, int condition, const voi
 		}
 		ast_devstate_changed(AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "PJSIP/%s", ast_sorcery_object_get_id(channel->session->endpoint));
 		break;
+	case AST_CONTROL_FLASH:
+		duration = 300;
+		digit = '!';
+		dtmf_data = info_dtmf_data_alloc(channel->session, digit, duration);
+
+		if (!dtmf_data) {
+			res = -1;
+			break;
+		}
+
+		if (ast_sip_push_task(channel->session->serializer, transmit_info_dtmf, dtmf_data)) {
+			ast_log(LOG_WARNING, "Error sending FLASH via INFO on channel %s\n", ast_channel_name(ast));
+			ao2_ref(dtmf_data, -1); /* dtmf_data can't be null here */
+			res = -1;
+		}
+		break;
 	case AST_CONTROL_VIDUPDATE:
 		for (i = 0; i < AST_VECTOR_SIZE(&channel->session->active_media_state->sessions); ++i) {
 			media = AST_VECTOR_GET(&channel->session->active_media_state->sessions, i);

doc/CHANGES-staging/chan_pjsip_flash.txt

@@ -0,0 +1,4 @@
+Subject: chan_pjsip
+
+Hook flash events can now be sent on a PJSIP channel
+if requested to do so.