Re: [hybi] #1: HTTP Compliance

[John Tamplin <[e-mail]>]

On Mon, May 17, 2010 at 5:29 AM, Maciej Stachowiak <[e-mail]> wrote:

> Ian has claimed that the extra bytes after the request help WebSocket fail
> early in the face of unaware proxies, though we do not yet have data showing
> this to be the case. We do know that without this, often the handshake will
> appear to succeed but transmitting messages will fail, for the network
> setups of many users.
>
> I don't think anyone has indicated a practical problem caused by the extra
> bytes.
>

I believe we have already had a real-world practical case where they did
cause a problem:

   - client sends WebSocket request that goes through a proxy, random bytes
   are not advertised in the Content-length
   - proxy doesn't know WebSocket, passes along connection to real server
   which does implement WebSocket
   - server waits reading random bytes which were not forwarded
   - server drops the connection after a timeout

Thus the random bytes did succeed in preventing a WebSocket connection
across a non-WS compliant proxy, but:

   1. the proxy was actually capable of forwarding the connection if the
   server had completed the request
   2. we had to wait for a timeout, so this was not a fast-fail situation
   3. the same thing could have been more easily accomplished by having a WS
   control frame exchanged at startup with similar results without
   non-compliant random bytes on the wire

-- 
John A. Tamplin
Software Engineer (GWT), Google