SDP: Fix wrong parameter size

bumble/sdp.py

@@ -594,7 +594,10 @@ class SDP_PDU:
 
     @classmethod
     def from_bytes(cls, pdu: bytes) -> SDP_PDU:
-        pdu_id, transaction_id, _parameters_length = struct.unpack_from('>BHH', pdu, 0)
+        pdu_id, transaction_id, parameters_length = struct.unpack_from('>BHH', pdu, 0)
+
+        if len(pdu) != 5 + parameters_length:
+            logger.warning("Expect %d bytes, got %d", 5 + parameters_length, len(pdu))
 
         subclass = cls.subclasses.get(pdu_id)
         if not (subclass := cls.subclasses.get(pdu_id)):
@@ -616,9 +619,11 @@ class SDP_PDU:
 
     def __bytes__(self):
         if self._payload is None:
-            self._payload = struct.pack(
-                '>BHH', self.pdu_id, self.transaction_id, 0
-            ) + hci.HCI_Object.dict_to_bytes(self.__dict__, self.fields)
+            parameters = hci.HCI_Object.dict_to_bytes(self.__dict__, self.fields)
+            self._payload = (
+                struct.pack('>BHH', self.pdu_id, self.transaction_id, len(parameters))
+                + parameters
+            )
         return self._payload
 
     @property

tests/sdp_test.py

@@ -18,9 +18,11 @@
 import asyncio
 import logging
 import os
+import re
 
 import pytest
 
+from bumble import sdp
 from bumble.core import BT_L2CAP_PROTOCOL_ID, UUID
 from bumble.sdp import (
     SDP_BROWSE_GROUP_LIST_ATTRIBUTE_ID,
@@ -206,6 +208,16 @@ def sdp_records(record_count=1):
     }
 
 
+# -----------------------------------------------------------------------------
+def test_pdu_parameter_length(caplog) -> None:
+    caplog.set_level(logging.WARNING)
+    pdu = sdp.SDP_ErrorResponse(
+        transaction_id=0, error_code=sdp.ErrorCode.INVALID_SDP_VERSION
+    )
+    assert sdp.SDP_PDU.from_bytes(bytes(pdu)) == pdu
+    assert not re.search("Expect \d+ bytes, got \d+", caplog.text)
+
+
 # -----------------------------------------------------------------------------
 @pytest.mark.asyncio
 async def test_service_search():