PRIORITY: fix body length validation

Author: Kriechi

HISTORY.rst

@@ -11,6 +11,7 @@ Release History
 **Bugfixes**
 
 - Fixed padding parsing for ``PushPromiseFrame``.
+- Fixed unchecked frame length for ``PriorityFrame``. It now correctly raises ``InvalidFrameError``.
 
 **Other Changes**
 

hyperframe/frame.py

@@ -323,8 +323,14 @@ def serialize_body(self):
         return self.serialize_priority_data()
 
     def parse_body(self, data):
+        if len(data) > 5:
+            raise InvalidFrameError(
+                "PRIORITY must have 5 byte body: actual length %s." %
+                len(data)
+            )
+
         self.parse_priority_data(data)
-        self.body_len = len(data)
+        self.body_len = 5
 
 
 class RstStreamFrame(Frame):

test/test_frames.py

@@ -262,6 +262,12 @@ def test_priority_frame_with_all_data_parses_properly(self):
         assert f.exclusive is True
         assert f.body_len == 5
 
+    def test_priority_frame_invalid(self):
+        with pytest.raises(ValueError):
+            decode_frame(
+                b'\x00\x00\x06\x02\x00\x00\x00\x00\x01\x80\x00\x00\x04\x40\xFF'
+            )
+
     def test_priority_frame_comes_on_a_stream(self):
         with pytest.raises(ValueError):
             PriorityFrame(0)