rtpengine: fix order of specified interface flags

When both 'external' and 'internal' flags were specified, 'internal' was
always assigned as iniface, and 'external' as outiface. This commit
makes sure that the order they are specified in is respected.

Author: razvancrainea

modules/rtpengine/rtpengine.c

@@ -1704,10 +1704,17 @@ static int parse_flags(struct ng_flags_parse *ng_flags, struct sip_msg *msg,
 				continue;
 
 			case 8:
-				if (str_eq(&key, "internal"))
-					iniface = key;
-				else if (str_eq(&key, "external"))
-					outiface = key;
+				if (str_eq(&key, "internal")) {
+					if (iniface.s)
+						outiface = key;
+					else
+						iniface = key;
+				} else if (str_eq(&key, "external")) {
+					if (iniface.s)
+						outiface = key;
+					else
+						iniface = key;
+				}
 				else if (str_eq(&key, "RTP/AVPF"))
 					ng_flags->transport = 0x102;
 				else if (str_eq(&key, "RTP/SAVP"))