bugfix: client: reject a handshake response whose status is not 101 - #104
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zhuizhuhaomeng merged 1 commit intoAug 17, 2026
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Per RFC 6455 section 4.1, a status code other than 101 means the server has not accepted the upgrade and the client must fail the connection. connect() only checked that the status line starts with "HTTP/1.1", so any plain HTTP response (403, 301, 502, ...) was reported as a successful handshake and subsequent frames were written into a non-WebSocket connection. Fixes openresty#47.
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zhuizhuhaomeng
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Aug 17, 2026
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What this fixes
client:connect()validates the handshake response with:Any HTTP/1.1 status line passes, so a server (or an intermediary that does not support
Upgrade, e.g. a load balancer) answering403,301, or502is reported as a successfully connected WebSocket. The caller then writes masked frames into a plain HTTP connection and only finds out via garbage on the nextrecv_frame(), with no way to distinguish this from a transient network error and react (e.g. fall back to a non-WebSocket transport).RFC 6455 section 4.1 requires the client to fail the connection whenever the handshake status is not
101.Change
connect()now captures the status code and returnsnil, "failed websocket handshake: unexpected response status: <code>", headerfor anything other than101. The raw response header is still returned as the third value so callers can inspect the full response.t/handshake.t: refused upgrade (403), redirect (301), and a success control againstresty.websocket.server.Fixes #47 (open since 2019, asking for exactly this check, at the
FIXME: verify the response headerssite).Related: #94 adds an opt-in
validate_handshakeoption as part of a larger feature. This PR is only the minimal always-on status check: treating a non-101 response as a connected WebSocket is never correct, so it should apply by default rather than behind a flag. Happy to rebase either way if the maintainers prefer the #94 approach.