[Feature Request] Add Unix Domain Socket support

[gubiao]

Is it possible to add Unix Domain Socket support?
I use Cloudflare CDN + Nginx(TLS) + Shadowsocks-rust + v2ray-plugin (websocket).
Nginx proxy my website and ss+v2ray-plugin at the same time.
It would be great if v2ray-plugin could add UDS support.
Many people told me that UDS is faster than a local loopback connection. I also found this:
https://stackoverflow.com/questions/14973942/tcp-loopback-connection-vs-unix-domain-socket-performance

My current Nginx configuration:
...
upstream myssserver {
server 127.0.0.1:8000;
keepalive 32;
keepalive_requests 2000;
keepalive_time 7d;
keepalive_timeout 7d;
}
...
location /haha {
proxy_pass http://myssserver;
proxy_socket_keepalive on;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $host;
proxy_next_upstream off;
proxy_redirect off;
proxy_connect_timeout 5s;
proxy_send_timeout 7d;
proxy_read_timeout 7d;
proxy_buffering off;
proxy_request_buffering off;
keepalive_requests 2000;
keepalive_time 7d;
keepalive_timeout 7d;
}
...

If v2ray-plugin can provide UDS support, then Nginx can communicate with v2ray-plugin through UDS:
upstream myssserver {
server unix:/myssserver.socks;
....
}

Communicating through the TCP connection of the network loopback address will result in a large number of 127.0.0.1->127.0.0.1 TCP connections.

[gubiao]

shadowsocks/shadowsocks-org#28