Re: [hybi] Handshake was: The WebSocket protocol issues.

[Willy Tarreau <[e-mail]>]

On Tue, Sep 28, 2010 at 10:30:14AM +1000, Greg Wilkins wrote:
> On 28 September 2010 09:26, Scott Ferguson <[e-mail]> wrote:
> > Greg Wilkins wrote:
> >>
> >> Scott,
> >>
> >> yes - I glossed over the details of what the actual hash should be in
> >> the ping packet.  I believe H(c-nonce, "WebSocket") is a good hash
> >> that indicates the server is a WS.
> >
> > That's not quite the issue. It's the second hash in the PONG that's missing,
> > because we also need to verify the client as a WS client and not a hijacked
> > HTTP client (or hijacked future non-websocket client):
> 
> OK, I've got it.
> 
> For your proposal of a server nonce, then a HELLO op-code is more
> appropriate than ping/pong as the pong should normally contain the
> same content as the ping.
> 
> So my proposal was:
> 
> HTTP(upgrade,nonce)   -->
> <-- HTTP(101)
> <-- WS(ping,hash(nonce,"WebSocket"))
> [ <-- * WS(op, data)  ]
> --> WS(pong,hash(nonce,"WebSocket"))   ; client calls onOpen
> [ * WS(op, data) -->  ]
> 
> 
> Your amendment is
> 
> HTTP(upgrade,c-nonce)   -->
> <-- HTTP(101)
> <-- WS(hello,hash(c-nonce,"WebSocket"),s-nonce)
> [ <-- * WS(op, data)  ]
> --> WS(hello,hash(s-nonce,"WebSocket"))   ; client call onOpen
> [ * WS(op, data) -->  ]
> 
> 
> I'm not 100% convinced that the server nonce is really necessary, as
> the client has already been validated by sending Sec-Headers and the
> upgrade in the first place, and the contents of the ping message must
> be copied into a pong message (and is not predictable if the nonce is
> hidden from the client).

I really think that if we can get a clean WS-based handshake, we can
get rid of the Sec-* headers, as the WS handshake will validate a much
more serious part of the protocol than the HTTP headers with their
tricks.

Willy