RFC Errata
RFC 6455, "The WebSocket Protocol", December 2011
Source of RFC: hybi (app)See Also: RFC 6455 w/ inline errata
Errata ID: 3433
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Eric Lawrence
Date Reported: 2012-12-20
Verifier Name: Barry Leiba
Date Verified: 2012-12-22
Section 11.3.2 says:
However, the |Sec-WebSocket-Extensions| header field MUST NOT appear more than once in an HTTP response.
It should say:
The |Sec-WebSocket-Extensions| header field MAY appear multiple times in an HTTP response (which is logically the same as a single |Sec-WebSocket-Extensions| header field that contains all values).
Notes:
Section 4.2.2 Step 5 subpart 6 (top of page 25) clearly explains that this header field may appear multiple times in the server's response: "If multiple extensions are to be used, they can all be listed in a single |Sec-WebSocket-Extensions| header field or split between multiple instances of the |Sec-WebSocket-Extensions| header field. This completes the server's handshake..."