Asserting ECN from userspace?

[Rick Jones]

On 10/04/2011 11:18 PM, David Täht wrote:
>
> No sooner had I noted (with pleasure) the kernel's new ability to
> correctly set the dscp bits on IPv6 TCP streams without messing with the
> negotiated ECN status, that I found several use cases where being able
> to assert ECN from userspace (for either ipv4, or ipv6) would be useful.
> ...
> 3) Web Proxies. A web proxy could note when it was experiencing
> congestion on one side of the proxied connection (or another) and signal
> the other side to slow down.
> ...
> As for 3... perhaps a grantable network capability? A proxy could
> acquire privs to twiddle those bits before dropping root privs.

For 3, couldn't/shouldn't the proxy simply stop draining the appropriate 
socket buffer to cause TCP's existing flow control to slow down that side?

rick jones