parser_ping: bugfix for handling of 0 payload length messages

Author: jaxxzer

src/protocol/parsers/parser_ping.h

@@ -77,9 +77,15 @@ class PingParser : public Parser
             state++;
             break;
         case WAIT_SRC_ID:
+            parseBuf.append(byte);
+            state++;
+            break;
         case WAIT_DST_ID:
             parseBuf.append(byte);
             state++;
+            if (payload_length == 0) { // no payload bytes
+                state++;
+            }
             break;
         case WAIT_PAYLOAD:
             parseBuf.append(byte);