Janus ping/pong message and updated documentation

Makefile.am

@@ -14,7 +14,7 @@ AM_CFLAGS += -Wredundant-decls  # sophiasip also contains redundant declarations
 # some fairly big refactoring though, which can wait.
 # AM_CFLAGS += -Wshadow -Wstrict-aliasing=2
 
-AM_CFLAGS += -fstack-protector-all -g -ggdb -rdynamic
+AM_CFLAGS += -fstack-protector-all -g -ggdb -fPIC -rdynamic
 
 # FIXME: make docs work with distcheck
 DISTCHECK_CONFIGURE_FLAGS = --disable-docs --enable-post-processing

janus.c

@@ -767,11 +767,21 @@ int janus_process_incoming_request(janus_request_source *source, json_t *root) {
 	const gchar *message_text = json_string_value(message);
 
 	if(session_id == 0 && handle_id == 0) {
-		/* Can only be a 'Create new session' or 'Get info' request */
+		/* Can only be a 'Create new session', a 'Get info' or a 'Ping/Pong' request */
 		if(!strcasecmp(message_text, "info")) {
 			ret = janus_process_success(source, "application/json", g_strdup(info_text));
 			goto jsondone;
 		}
+		if(!strcasecmp(message_text, "ping")) {
+			/* Prepare JSON reply */
+			json_t *reply = json_object();
+			json_object_set_new(reply, "janus", json_string("pong"));
+			json_object_set_new(reply, "transaction", json_string(transaction_text));
+			char *reply_text = json_dumps(reply, JSON_INDENT(3) | JSON_PRESERVE_ORDER);
+			json_decref(reply);
+			ret = janus_process_success(source, "application/json", g_strdup(reply_text));
+			goto jsondone;
+		}
 		if(strcasecmp(message_text, "create")) {
 			ret = janus_process_error(source, session_id, transaction_text, JANUS_ERROR_INVALID_REQUEST_PATH, "Unhandled request '%s' at this path", message_text);
 			goto jsondone;

mainpage.dox

@@ -855,6 +855,71 @@ GET http://host:port/janus/<sessionid>?max_events=5
 		"sdp" : "v=0\r\no=[..more sdp stuff..]"
 	}
 }
+\endverbatim
+ *
+ * If you're going to \c trickle candidates rather than including them
+ * all in an SDP OFFER or ANSWER, there is an ad-hoc message you can use
+ * to do so which is called, unsurprisingly, \c trickle and which you
+ * can use to send one or more trickle candidates to Janus. Since such
+ * a message is related to a specific PeerConnection, it will need to be
+ * addressed to the right Handle just as the \c message introduced
+ * previously. A \c trickle message can contain three different kind of
+ * information:
+ *
+ *  - a single trickle candidate;
+ *  - an array of trickle candidates;
+ *  - a null candidate or a \c completed JSON object to notify the end of the
+ * candidates.
+ *
+ * This is an example of a single candidate being trickled:
+ *
+\verbatim
+{
+	"janus" : "trickle",
+	"transaction" : "hehe83hd8dw12e",
+	"candidate" : {
+		"sdpMid" : "video",
+		"sdpMLineIndex" : 1,
+		"candidate" : "..."
+	}
+}
+\endverbatim
+ *
+ * This, instead, is an example of how to group more trickle candidates
+ * in a single request (particularly useful if you're wrapping Janus in
+ * your server and want to reduce the number of transactions):
+ *
+\verbatim
+{
+	"janus" : "trickle",
+	"transaction" : "hehe83hd8dw12e",
+	"candidate" : [ 
+		{
+			"sdpMid" : "video",
+			"sdpMLineIndex" : 1,
+			"candidate" : "..."
+		},
+		{
+			"sdpMid" : "video",
+			"sdpMLineIndex" : 1,
+			"candidate" : "..."
+		},
+		[..]
+	]
+}
+\endverbatim
+ *
+ * Finally, this is how you can tell Janus that you sent all the trickle
+ * candidates that were gathered:
+ *
+\verbatim
+{
+	"janus" : "trickle",
+	"transaction" : "hehe83hd8dw12e",
+	"candidate" : {
+		"completed" : true
+	}
+}
 \endverbatim
  *
  * Plugins may handle this requests synchronously or asynchronously. In

plugins/janus_recordplay.c

@@ -902,6 +902,7 @@ static void *janus_recordplay_handler(void *data) {
 				JANUS_LOG(LOG_ERR, "Not a playout session, can't start\n");
 				error_code = JANUS_RECORDPLAY_ERROR_INVALID_STATE;
 				g_snprintf(error_cause, 512, "Not a playout session, can't start");
+				goto error;
 			}
 			/* Just a final message we make use of, e.g., to receive an ANSWER to our OFFER for a playout */
 			if(!msg->sdp) {

rtcp.c

@@ -383,6 +383,48 @@ int janus_rtcp_remove_nacks(char *packet, int len) {
 	return len;
 }
 
+/* Query an existing REMB message */
+uint64_t janus_rtcp_get_remb(char *packet, int len) {
+	if(packet == NULL || len == 0)
+		return 0;
+	rtcp_header *rtcp = (rtcp_header *)packet;
+	if(rtcp->version != 2)
+		return 0;
+	/* Get REMB bitrate, if any */
+	int total = len;
+	while(rtcp) {
+		if(rtcp->type == RTCP_PSFB) {
+			gint fmt = rtcp->rc;
+			if(fmt == 15) {
+				rtcp_fb *rtcpfb = (rtcp_fb *)rtcp;
+				rtcp_remb *remb = (rtcp_remb *)rtcpfb->fci;
+				if(remb->id[0] == 'R' && remb->id[1] == 'E' && remb->id[2] == 'M' && remb->id[3] == 'B') {
+					/* FIXME From rtcp_utility.cc */
+					unsigned char *_ptrRTCPData = (unsigned char *)remb;
+					_ptrRTCPData += 4;	/* Skip unique identifier and num ssrc */
+					//~ JANUS_LOG(LOG_VERB, " %02X %02X %02X %02X\n", _ptrRTCPData[0], _ptrRTCPData[1], _ptrRTCPData[2], _ptrRTCPData[3]);
+					uint8_t brExp = (_ptrRTCPData[1] >> 2) & 0x3F;
+					uint32_t brMantissa = (_ptrRTCPData[1] & 0x03) << 16;
+					brMantissa += (_ptrRTCPData[2] << 8);
+					brMantissa += (_ptrRTCPData[3]);
+					uint64_t bitrate = brMantissa << brExp;
+					JANUS_LOG(LOG_VERB, "Got REMB bitrate %"SCNu64"\n", bitrate);
+					return bitrate;
+				}
+			}
+		}
+		/* Is this a compound packet? */
+		int length = ntohs(rtcp->length);
+		if(length == 0)
+			break;
+		total -= length*4+4;
+		if(total <= 0)
+			break;
+		rtcp = (rtcp_header *)((uint32_t*)rtcp + length + 1);
+	}
+	return 0;
+}
+
 /* Change an existing REMB message */
 int janus_rtcp_cap_remb(char *packet, int len, uint64_t bitrate) {
 	if(packet == NULL || len == 0)

rtcp.h

@@ -216,6 +216,12 @@ GSList *janus_rtcp_get_nacks(char *packet, int len);
  * have been handled. */
 int janus_rtcp_remove_nacks(char *packet, int len);
 
+/*! \brief Inspect an existing RTCP REMB message to retrieve the reported bitrate
+ * @param[in] packet The message data
+ * @param[in] len The message data length in bytes
+ * @returns The reported bitrate if successful, 0 if no REMB packet was available */
+uint64_t janus_rtcp_get_remb(char *packet, int len);
+
 /*! \brief Method to modify an existing RTCP REMB message to cap the reported bitrate
  * @param[in] packet The message data
  * @param[in] len The message data length in bytes