Always return bytes from recv().

Previously, a bytearray was returned when a client received
fragments without reassembly while compression was disabled.

The additional bytes() call is a no-op in all other cases.

Refs #1641.

Author: aaugustin

src/websockets/asyncio/messages.py

@@ -179,6 +179,7 @@ async def get(self, decode: bool | None = None) -> Data:
         finally:
             self.get_in_progress = False
 
+        # This converts frame.data to bytes when it's a bytearray.
         data = b"".join(frame.data for frame in frames)
         if decode:
             return data.decode()
@@ -243,7 +244,8 @@ async def get_iter(self, decode: bool | None = None) -> AsyncIterator[Data]:
             decoder = UTF8Decoder()
             yield decoder.decode(frame.data, frame.fin)
         else:
-            yield frame.data
+            # Convert to bytes when frame.data is a bytearray.
+            yield bytes(frame.data)
 
         # Following frames, for fragmented messages
         while not frame.fin:
@@ -257,7 +259,8 @@ async def get_iter(self, decode: bool | None = None) -> AsyncIterator[Data]:
             if decode:
                 yield decoder.decode(frame.data, frame.fin)
             else:
-                yield frame.data
+                # Convert to bytes when frame.data is a bytearray.
+                yield bytes(frame.data)
 
         self.get_in_progress = False
 

src/websockets/legacy/protocol.py

@@ -1025,7 +1025,7 @@ async def read_message(self) -> Data | None:
 
         # Shortcut for the common case - no fragmentation
         if frame.fin:
-            return frame.data.decode() if text else frame.data
+            return frame.data.decode() if text else bytes(frame.data)
 
         # 5.4. Fragmentation
         fragments: list[Data] = []

src/websockets/sync/messages.py

@@ -193,6 +193,7 @@ def get(self, timeout: float | None = None, decode: bool | None = None) -> Data:
         finally:
             self.get_in_progress = False
 
+        # This converts frame.data to bytes when it's a bytearray.
         data = b"".join(frame.data for frame in frames)
         if decode:
             return data.decode()
@@ -255,7 +256,8 @@ def get_iter(self, decode: bool | None = None) -> Iterator[Data]:
             decoder = UTF8Decoder()
             yield decoder.decode(frame.data, frame.fin)
         else:
-            yield frame.data
+            # Convert to bytes when frame.data is a bytearray.
+            yield bytes(frame.data)
 
         # Following frames, for fragmented messages
         while not frame.fin:
@@ -266,7 +268,8 @@ def get_iter(self, decode: bool | None = None) -> Iterator[Data]:
             if decode:
                 yield decoder.decode(frame.data, frame.fin)
             else:
-                yield frame.data
+                # Convert to bytes when frame.data is a bytearray.
+                yield bytes(frame.data)
 
         self.get_in_progress = False