Add missing Feedback Control Information size check when getting receiver ssrc from PLIs

Author: atoppi

src/rtcp.c

@@ -145,8 +145,13 @@ guint32 janus_rtcp_get_receiver_ssrc(char *packet, int len) {
 			}
 			case RTCP_PSFB: {
 				/* PSFB, Payload-specific FB message (rfc4585) */
-				janus_rtcp_fb *rtcpfb = (janus_rtcp_fb *)rtcp;
-				return ntohl(rtcpfb->media);
+				if(rtcp->rc == 1) {
+					/* PLI has no FCI data */
+					if (!janus_rtcp_check_fci(rtcp, total, 0))
+						break;
+					janus_rtcp_fb *rtcpfb = (janus_rtcp_fb *)rtcp;
+					return ntohl(rtcpfb->media);
+				}
 			}
 			default:
 				break;