Handle blank commands in IRCMessages

See ircdocs/parser-tests#20

Author: paravoid

ircstream.py

@@ -175,7 +175,11 @@ def from_message(cls, message: str) -> IRCMessage:
             source = parts[0][1:]
             parts = parts[1:]
 
-        command = parts[0].upper()
+        try:
+            command = parts[0].upper()
+        except IndexError:
+            raise ValueError("Invalid IRC message (no command specified)")
+
         original_params = parts[1:]
         params = []
 
@@ -379,7 +383,12 @@ def _handle_line(self, bline: bytes) -> None:
             if not line:
                 return
             self.log.debug("Data received", message=line)
-            msg = IRCMessage.from_message(line)
+
+            try:
+                msg = IRCMessage.from_message(line)
+            except ValueError:
+                # ignore unparseable commands
+                return
 
             whitelisted = ("CAP", "PASS", "USER", "NICK", "QUIT", "PING", "PONG")
             if not self.identified and msg.command not in whitelisted:

tests/test_rawsocket.py

@@ -113,6 +113,10 @@ def test_erroneous(clientsock):
     data = clientsock.readlines()
     assert any([b"432 *" in response for response in data])
 
+    clientsock.sendall(b":NOCOMMAND\n")
+    data = clientsock.readlines()
+    assert data == []
+
 
 def test_unicodeerror(ircserver, clientsock):
     """Test for UnicodeError handling in both directions."""