Add fuzz target for WebSocket parser.

Author: aaugustin

fuzzing/fuzz_websocket_parser.py

@@ -0,0 +1,46 @@
+import sys
+
+import atheris
+
+
+with atheris.instrument_imports():
+    from websockets.exceptions import PayloadTooBig, ProtocolError
+    from websockets.frames import Frame
+    from websockets.streams import StreamReader
+
+
+def test_one_input(data):
+    fdp = atheris.FuzzedDataProvider(data)
+    mask = fdp.ConsumeBool()
+    max_size_enabled = fdp.ConsumeBool()
+    max_size = fdp.ConsumeInt(4)
+    payload = fdp.ConsumeBytes(atheris.ALL_REMAINING)
+
+    reader = StreamReader()
+    reader.feed_data(payload)
+    reader.feed_eof()
+
+    parser = Frame.parse(
+        reader.read_exact,
+        mask=mask,
+        max_size=max_size if max_size_enabled else None,
+    )
+
+    try:
+        next(parser)
+    except StopIteration:
+        pass  # response is available in exc.value
+    except (
+        PayloadTooBig,  # frame's payload size exceeds ``max_size``
+        ProtocolError,  # frame contains incorrect values
+    ):
+        pass
+
+
+def main():
+    atheris.Setup(sys.argv, test_one_input)
+    atheris.Fuzz()
+
+
+if __name__ == "__main__":
+    main()