gh-141938/fix-http-client-state-reset

[pareshjoshij]

Closes gh-141938

Context:
As reported in gh-141938, when using http.client, if an OSError (such as TimeoutError or ConnectionRefusedError) occurs during _send_request—specifically after the state has transitioned to _CS_REQ_STARTED—the HTTPConnection object remains in a "dirty" state.

Because the state is not reset to _CS_IDLE, the connection object becomes unusable. Any subsequent attempts to use .request(), even after calling .connect(), result in a CannotSendRequest error.

The Fix:

1. Logic Change in request(): Wrapped _send_request in a try...except OSError block.
   • If an OSError occurs, we check errno.
   • If the error is not errno.EPIPE (Broken Pipe), self.close() is called explicitly. This resets the internal state machine (self.__state) to _CS_IDLE and closes the socket.
   • Note: errno.EPIPE is excluded to preserve existing behavior where a server closes the connection early (e.g., sending a 413 response), allowing the client to still read the response (prevents regression in test_epipe).
2. Testability Change in __init__(): Changed self._create_connection to use a lambda instead of capturing socket.create_connection directly.
   • This ensures that socket.create_connection is looked up at call time, allowing unit tests to properly mock it for individual requests without the mock being permanently captured by the instance.

Verification:

• Added HTTPConnectionStateTests to Lib/test/test_httplib.py.
• Verified that TimeoutError resets state to Idle (previously stuck at Request-sent) and closes the socket.
• Verified that a subsequent conn.request() call proceeds without raising CannotSendRequest.
• Verified locally that test_epipe passes, ensuring no regression for broken pipe scenarios.