Add debugging attributes to `ssh_agent.TrailingDataError` (837e1f6) - derivepassphrase.git

Add debugging attributes to `ssh_agent.TrailingDataError`

Marco Ricci commited on 2025-12-27 14:43:35
Zeige 1 geänderte Dateien mit 23 Einfügungen und 2 Löschungen.

The old implementation did not record *which* trailing data we were
seeing, on the grounds that well-behaved SSH agents would not send any
trailing data anyway (i.e., that this error condition was a failsafe).
However, while implementing Windows named pipe support, I observed
Pageant sporadically returning malformed responses that trigger this
error.  Without actually recording the trailing data, it is hard to
understand whether this is Pageant's fault (unlikely) or ours (more
likely), and specifically, whether we're implementing the protocol
incorrectly (unlikely), or rather the communication channel (much more
likely).  So the `TrailingDataError` class now optionally records the
actual raw response and the trailing data portion that caused the error,
to aid debugging.

src/derivepassphrase/ssh_agent/__init__.py f73cd8b..9ea14f8

src/derivepassphrase/ssh_agent/__init__.py

Zeige Datei @ 837e1f6

@@ -36,8 +36,27 @@ HEAD_LEN = 4
 class TrailingDataError(RuntimeError):
     """The result contained trailing data."""
 
-    def __init__(self) -> None:
+    def __init__(
+        self, raw: bytes | bytearray = b"", trailing: bytes | bytearray = b""
+    ) -> None:
         super().__init__("Overlong response from SSH agent")
+        self.raw = bytes(raw)
+        self.trailing = bytes(trailing)
+
+    def __str__(self) -> str:  # pragma: no cover [debug]
+        if self.raw or self.trailing:
+            return (
+                f"Overlong response from SSH agent: "
+                f"raw = {self.raw!r}, trailing = {self.trailing!r}"
+            )
+        return super().__str__()
+
+    def __repr__(self) -> str:  # pragma: no cover [debug]
+        """"""  # noqa: D419
+        return (
+            f"{self.__class__.__name__}"
+            f"(raw={self.raw!r}, trailing={self.trailing!r})"
+        )
 
 
 class SSHAgentFailedError(RuntimeError):
@@ -575,7 +594,9 @@ class SSHAgentClient:
             # Both `key` and `comment` are not wrapped as SSH strings.
             keys.append(_types.SSHKeyCommentPair(key, comment))
         if response_stream:
-            raise TrailingDataError
+            raise TrailingDataError(
+                raw=response, trailing=bytes(response_stream)
+            )
         return keys
 
     def sign(


...	...	@@ -36,8 +36,27 @@ HEAD_LEN = 4
36	36	class TrailingDataError(RuntimeError):
37	37	"""The result contained trailing data."""
38	38
39		- def __init__(self) -> None:
	39	+ def __init__(
	40	+ self, raw: bytes \| bytearray = b"", trailing: bytes \| bytearray = b""
	41	+ ) -> None:
40	42	super().__init__("Overlong response from SSH agent")
	43	+ self.raw = bytes(raw)
	44	+ self.trailing = bytes(trailing)
	45	+
	46	+ def __str__(self) -> str: # pragma: no cover [debug]
	47	+ if self.raw or self.trailing:
	48	+ return (
	49	+ f"Overlong response from SSH agent: "
	50	+ f"raw = {self.raw!r}, trailing = {self.trailing!r}"
	51	+ )
	52	+ return super().__str__()
	53	+
	54	+ def __repr__(self) -> str: # pragma: no cover [debug]
	55	+ """""" # noqa: D419
	56	+ return (
	57	+ f"{self.__class__.__name__}"
	58	+ f"(raw={self.raw!r}, trailing={self.trailing!r})"
	59	+ )
41	60
42	61
43	62	class SSHAgentFailedError(RuntimeError):
...	...	@@ -575,7 +594,9 @@ class SSHAgentClient:
575	594	# Both `key` and `comment` are not wrapped as SSH strings.
576	595	keys.append(_types.SSHKeyCommentPair(key, comment))
577	596	if response_stream:
578		- raise TrailingDataError
	597	+ raise TrailingDataError(
	598	+ raw=response, trailing=bytes(response_stream)
	599	+ )
579	600	return keys
580	601
581	602	def sign(
582	603