Avoid encoding errors in PING and PONG frame logging

docs/project/changelog.rst

@@ -50,6 +50,9 @@ Bug fixes
 * Fixed a regression from 16.1 where the legacy implementation rejected
   non-ASCII headers.
 
+* Escaped non-ASCII text in PING and PONG frame log messages to avoid errors
+  with non-UTF-8 log handlers.
+
 .. _17.1:
 
 17.1

src/websockets/frames.py

@@ -193,6 +193,12 @@ def _data_repr(self) -> tuple[str, bool | None]:
         # display UTF-8 text in binary frames nicely and generally to be helpful
         # and robust. Also support frames fragmented within UTF-8 sequences.
 
+        def repr_text(data: bytes) -> str:
+            decoded = data.decode(errors="replace")
+            # Ping and pong payloads may be generated internally. Escape
+            # non-ASCII characters so logging them is safe for any encoding.
+            return ascii(decoded) if self.opcode in (PING, PONG) else repr(decoded)
+
         if len(self.data) > 4 * self.MAX_LOG_SIZE:
             # Process only the start and the end, as the middle will be elided.
             # Cast to bytes because self.data could be a memoryview.
@@ -206,7 +212,7 @@ def _data_repr(self) -> tuple[str, bool | None]:
                 must_end_clean=self.fin,
             )
             if is_text:
-                data_repr = repr((data_start + data_end).decode(errors="replace"))
+                data_repr = repr_text(data_start + data_end)
 
         else:
             # Cast to bytes because self.data could be a memoryview.
@@ -217,7 +223,7 @@ def _data_repr(self) -> tuple[str, bool | None]:
                 must_end_clean=self.fin,
             )
             if is_text:
-                data_repr = repr(data.decode(errors="replace"))
+                data_repr = repr_text(data)
 
         # When the payload is text (except perhaps for boundaries), we decoded
         # enough in ``data_repr``. Now, do the same when the payload is binary.

tests/test_frames.py

@@ -364,6 +364,14 @@ def test_ping_text(self):
             "PING 'ping' [text, 4 bytes]",
         )
 
+    def test_ping_pong_text_is_ascii(self):
+        for opcode in (PING, PONG):
+            with self.subTest(opcode=opcode):
+                self.assertEqual(
+                    str(Frame(opcode, b"F\xd6\x8a}")),
+                    f"{opcode.name} " + "'F\\u058a}' [text, 4 bytes]",
+                )
+
     def test_ping_text_with_newline(self):
         self.assertEqual(
             str(Frame(PING, b"ping\n")),