I've implemented basic socks v5 client.
The code is similar to the socks4 class and partially taken from the em-http-request gem.
Currently only "No authentication" method is supported.
Added Socks5 protocol
IPv6 address support
Simplified IPv6 check
Fixed response parsing for IPv6 and Domain address types
I've extracted socks5 into a common component: https://github.com/igrigorik/em-socksify
In theory, no need to pull this into core anymore.
Closing - thanks for your ongoing maintenance of em-socksify @igrigorik!