PYTHON-940 - Unhelpful and pretty wrong error message.

Author: aherlihy

pymongo/network.py

@@ -60,13 +60,19 @@ def receive_message(sock, operation, request_id):
  header = _receive_data_on_socket(sock, 16)
  length = _UNPACK_INT(header[:4])[0]
 
+ actual_op = _UNPACK_INT(header[12:])[0]
+ assert operation == actual_op, ("wire protocol error: "
+ "unknown opcode %r" % (actual_op,))
  # No request_id for exhaust cursor "getMore".
  if request_id is not None:
  response_id = _UNPACK_INT(header[8:12])[0]
- assert request_id == response_id, "ids don't match %r %r" % (
- request_id, response_id)
+ assert request_id == response_id, (
+ "wire protocol error: got response id %r but expected %r"
+ % (response_id, request_id))
+
+ assert length > 16, ("wire protocol error: message length is shorter"
+ " than standard message header: %r" % (length,))
 
- assert operation == _UNPACK_INT(header[12:])[0]
  return _receive_data_on_socket(sock, length - 16)