https://www.w3.org/Bugs/Public/show_bug.cgi?id=23576
Bug ID: 23576
Summary: Clarify what to do when received null value
subprotocol in reply to non-empty subprotocol
Product: WebAppsWG
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P2
Component: WebSocket API (editor: Ian Hickson)
Assignee: [email protected]
Reporter: [email protected]
QA Contact: [email protected]
CC: [email protected], [email protected]
The spec has this text at the beginning of the text defining constructor's
behavior.
> The connection will only be established if the server reports that it has
> selected one of these subprotocols.
Though this may be intended to explain the role of the protocols argument
briefly and non-normatively, we interpreted that this text adds a requirement
that a WebSocket client MUST abort connection establishment if the peer server
doesn't select any subprotocol offered by the client. It should correspond to
null response to Sec-WebSocket-Protocol which is indicated by not including
Sec-WebSocket-Protocol header as defined in RFC 6455. RFC 6455 itself doesn't
require a client to abort connection establishment.
Let's use explicit language here to make it clear how to deal with this case. I
suggest that we remove this sentence and instead add this text to the end of
step 8.
"When <i>protocols</i> is non-empty and the <i>subprotocol in use</i> returned
by the server is null value, the user agent must <i>fail the WebSocket
connection</i>."
----
RFC 6455 is incomplete about subprotocol validation. It specifies the WebSocket
protocol layer to fail on the following cases:
1) no subprotocol in req && subprotocol in res
2) subprotocol(s) in req && subprotocol in res but doesn't match any of ones in
req
but not for
3) subprotocol(s) in req && not subprotocol in res
Thinking of the purpose of subprotocol, 3) should also be considered to be a
response that should result in giving up establishment of a WebSocket
connection. So, I think the clarification I proposed above should make sense.
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