Fixed incorrect DSCP value being set (see #2055)

conf/janus.jcfg.sample.in

@@ -207,14 +207,14 @@ media: {
 	#dtls_timeout = 500
 
 	# If you need DSCP packet marking and prioritization, you can configure
-	# the 'dscp_tos' property to a specific values, and Janus will try to
+	# the 'dscp' property to a specific values, and Janus will try to
 	# set it on all outgoing packets using libnice. Normally, the specs
 	# suggest to use different values depending on whether audio, video
 	# or data are used, but since all PeerConnections in Janus are bundled,
 	# we can only use one. You can refer to this document for more info:
 	# https://tools.ietf.org/html/draft-ietf-tsvwg-rtcweb-qos-18#page-6
 	# That said, DON'T TOUCH THIS IF YOU DON'T KNOW WHAT IT MEANS!
-	#dscp_tos = 46
+	#dscp = 46
 }
 
 # NAT-related stuff: specifically, you can configure the STUN/TURN

ice.c

@@ -451,16 +451,16 @@ uint janus_get_twcc_period(void) {
 	return twcc_period;
 }
 
-/* DSCP Type of Service, which we can set via libnice: it's disabled by default */
-static int dscp_tos = 0;
-void janus_set_dscp_tos(int tos) {
-	dscp_tos = tos;
-	if(dscp_tos > 0) {
-		JANUS_LOG(LOG_VERB, "Setting DSCP Type of Service to %ds\n", dscp_tos);
+/* DSCP value, which we can set via libnice: it's disabled by default */
+static int dscp_ef = 0;
+void janus_set_dscp(int dscp) {
+	dscp_ef = dscp;
+	if(dscp_ef > 0) {
+		JANUS_LOG(LOG_VERB, "Setting DSCP EF to %d\n", dscp_ef);
 	}
 }
-int janus_get_dscp_tos(void) {
-	return dscp_tos;
+int janus_get_dscp(void) {
+	return dscp_ef;
 }
 
 
@@ -3458,9 +3458,9 @@ int janus_ice_setup_local(janus_ice_handle *handle, int offer, int audio, int vi
 	}
 	/* Now create an ICE stream for all the media we'll handle */
 	handle->stream_id = nice_agent_add_stream(handle->agent, 1);
-	if(dscp_tos > 0) {
-		/* A DSCP Type of Service was configured, pass it to libnice */
-		nice_agent_set_stream_tos(handle->agent, handle->stream_id, dscp_tos);
+	if(dscp_ef > 0) {
+		/* A DSCP value was configured, shift it and pass it to libnice as a TOS */
+		nice_agent_set_stream_tos(handle->agent, handle->stream_id, dscp_ef << 2);
 	}
 	janus_ice_stream *stream = g_malloc0(sizeof(janus_ice_stream));
 	janus_refcount_init(&stream->ref, janus_ice_stream_free);

ice.h

@@ -151,12 +151,12 @@ void janus_set_twcc_period(uint period);
 /*! \brief Method to get the current TWCC period (see above)
  * @returns The current TWCC period */
 uint janus_get_twcc_period(void);
-/*! \brief Method to modify the DSCP Type of Service (TOS), which is disabled by default
- * @param[in] tos The new TOS value (0 to disable) */
-void janus_set_dscp_tos(int period);
-/*! \brief Method to get the current DSCP Type of Service (see above)
- * @returns The current TOS value (0 if disabled) */
-int janus_get_dscp_tos(void);
+/*! \brief Method to modify the DSCP value to set, which is disabled by default
+ * @param[in] dscp The new DSCP value (0 to disable) */
+void janus_set_dscp(int dscp);
+/*! \brief Method to get the current DSCP value (see above)
+ * @returns The current DSCP value (0 if disabled) */
+int janus_get_dscp(void);
 /*! \brief Method to modify the event handler statistics period (i.e., the number of seconds that should pass before Janus notifies event handlers about media statistics for a PeerConnection)
  * @param[in] period The new period value, in seconds */
 void janus_ice_set_event_stats_period(int period);

janus.c

@@ -300,8 +300,8 @@ static json_t *janus_info(const char *transaction) {
 	json_object_set_new(info, "mdns-enabled", janus_ice_is_mdns_enabled() ? json_true() : json_false());
 	json_object_set_new(info, "min-nack-queue", json_integer(janus_get_min_nack_queue()));
 	json_object_set_new(info, "twcc-period", json_integer(janus_get_twcc_period()));
-	if(janus_get_dscp_tos() > 0)
-		json_object_set_new(info, "dscp-tos", json_integer(janus_get_dscp_tos()));
+	if(janus_get_dscp() > 0)
+		json_object_set_new(info, "dscp", json_integer(janus_get_dscp()));
 	if(janus_ice_get_stun_server() != NULL) {
 		char server[255];
 		g_snprintf(server, 255, "%s:%"SCNu16, janus_ice_get_stun_server(), janus_ice_get_stun_port());
@@ -4645,13 +4645,15 @@ gint main(int argc, char *argv[])
 	}
 
 	/* Is there any DSCP TOS to apply? */
-	item = janus_config_get(config, config_media, janus_config_type_item, "dscp_tos");
+	item = janus_config_get(config, config_media, janus_config_type_item, "dscp");
+	if(!item || !item->value)	/* Just for backwards compatibility */
+		item = janus_config_get(config, config_media, janus_config_type_item, "dscp_tos");
 	if(item && item->value) {
-		int tos = atoi(item->value);
-		if(tos < 0) {
-			JANUS_LOG(LOG_WARN, "Ignoring dscp_tos value as it's not a positive integer\n");
+		int dscp = atoi(item->value);
+		if(dscp < 0) {
+			JANUS_LOG(LOG_WARN, "Ignoring dscp value as it's not a positive integer\n");
 		} else {
-			janus_set_dscp_tos(tos);
+			janus_set_dscp(dscp);
 		}
 	}