elaborate reasons of header parsing failure

shadowsocks/common.py

@@ -171,8 +171,8 @@ def parse_header(data):
         else:
             logging.warn('header is too short')
     else:
-        logging.warn('unsupported addrtype %d, maybe wrong password' %
-                     addrtype)
+        logging.warn('unsupported addrtype %d, maybe wrong password or '
+                     'encryption method' % addrtype)
     if dest_addr is None:
         return None
     return addrtype, to_bytes(dest_addr), dest_port, header_length