connectd: treat websocket handshake headers as case-insensitive - #9308
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| "sec-websocket-version: 13\r\n\r\n"; | ||
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| my_rbuf = tal_strdup(tmpctx, hdr); | ||
| my_rbuf_off = 0; |
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HTTP header field names are case-insensitive (RFC 9110 section 5.1) and RFC 6455 says the Upgrade and Connection values are treated as ASCII case-insensitive, as the comment in websocketd.c already quotes. The handshake parser matched header names byte-exactly and the values with case-sensitive strstr, so any client that normalizes header casing got 400: notably Node.js's built-in WebSocket (undici) lowercases all request headers and can never connect to a bind-addr=ws: listener, while browsers happen to send RFC casing and work. Match header names case-insensitively in get_http_hdr and use a case-insensitive search for the Upgrade and Connection values. The Sec-WebSocket-Version value comparison stays exact and the key is base64 data, unchanged. Extends the unit test with a lowercased handshake as sent by Node. Fixes ElementsProject#9307 Changelog-Fixed: connectd: the WebSocket port now accepts handshakes from clients that send lowercase HTTP header names, such as Node.js's built-in WebSocket. Signed-off-by: Corey Phillips <corey.lyle.phillips@proton.me>
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Fixes #9307.
The websocket handshake parser matches header names byte-exactly (get_http_hdr) and the Upgrade/Connection values with case-sensitive strstr. Header field names are case-insensitive per RFC 9110 section 5.1, and RFC 6455 says the Upgrade and Connection values are "treated as an ASCII case-insensitive value" (already quoted in the comment above http_respond).
Practical impact: Node.js's built-in WebSocket (undici) lowercases all request headers, so it can never connect to a bind-addr=ws: listener and gets "400 I only speak websocket". Browsers happen to send RFC casing and work.
Changes:
Verified the failure mode against a live v26.06.1 bind-addr=ws: listener with raw replays (lowercased names rejected before, accepted with this change per the unit test vector).