constrained socket buffers patch

[Juliusz Chroboczek]

> attached is the constrained sockets patch.

I'd like to know how this will interact with tor's circuit selection.

If I understand this patch correctly, it sets the SO_SNDBUF and
SO_RCVBUF socket options so as to limit the maximum size of the TCP
send and receive windows respectively.

Now the throughput (``bandwidth'') of a TCP connection is limited by
window/rtt.  What this means is that with ConstrainedSockets enabled,
your tor server will have basically unlimited throughput on a local
connection, but be limited to roughly 40 kB/s per connection (that's
bytes, not bits) over a transatlantic link[1].

Perhaps one of the tor developers could clarify whether tor's circuit
selection and congestion control can deal with server's whose per-
connection throughpout (but not necessarily aggregate throughput) is
widely dependent on where you come from?

                                        Juliusz