Fixed maximum length of route metadata

rsocket/extensions/tagging.py

@@ -25,10 +25,10 @@ def _serialize_tags(self) -> bytes:
         serialized = b''
 
         for tag in list(map(ensure_bytes, self.tags)):
-            if len(tag) > 256:
-                raise RSocketError('Tag length longer than 256 characters: "%s"' % tag)
+            if len(tag) > 255:
+                raise RSocketError('Tag length longer than 255 characters: "%s"' % tag)
 
-            serialized += struct.pack('>b', len(tag))
+            serialized += struct.pack('>B', len(tag))
             serialized += tag
 
         return serialized
@@ -38,7 +38,7 @@ def parse(self, buffer: bytes):
         offset = 0
 
         while offset < len(buffer):
-            tag_length = struct.unpack('>b', buffer[offset:offset + 1])[0]
+            tag_length = struct.unpack('>B', buffer[offset:offset + 1])[0]
             offset += 1
             self.tags.append(buffer[offset:offset + tag_length])
             offset += tag_length

tests/test_tagging.py

@@ -0,0 +1,31 @@
+import struct
+import unittest
+
+from rsocket.exceptions import RSocketError
+from rsocket.extensions.tagging import TaggingMetadata
+from rsocket.extensions.mimetypes import WellKnownMimeTypes
+
+
+class TestTaggingMetadata(unittest.TestCase):
+    def test_serialize_max_length(self):
+        tag = 's' * 255
+        meta = TaggingMetadata(WellKnownMimeTypes.MESSAGE_RSOCKET_ROUTING, [tag])
+        serialized = meta.serialize()
+        length = struct.pack('>B', len(tag))
+        self.assertEquals(length + bytes(tag, 'utf-8'), serialized)
+
+    def test_serialize_exception_length(self):
+        tag = 's' * 256
+        meta = TaggingMetadata(WellKnownMimeTypes.MESSAGE_RSOCKET_ROUTING, [tag])
+        with self.assertRaisesRegex(RSocketError, f'Tag length longer than 255 characters: "b\'{tag}\'"'):
+            meta.serialize()
+
+    def test_parse(self):
+        meta = TaggingMetadata(WellKnownMimeTypes.MESSAGE_RSOCKET_ROUTING)
+
+        tag = 's' * 255
+        length = struct.pack('>B', len(tag))
+
+        meta.parse(length + bytes(tag, 'utf-8'))
+
+        self.assertEquals(tag, meta.tags[0].decode())