Unix socket support

[dafortune]

Hi!

When using an unix socket instead of a tcp port req.connection.remoteAddress is undefined. And forwarded adds that undefined value to the array of forwarded IPs (https://github.com/jshttp/proxy-addr/blob/master/index.js#L57). So given that undefined is not a valid ip https://github.com/jshttp/proxy-addr/blob/master/index.js#L254 returns false for the index 0 and so no IP is trusted.

If are you willing to accept a PR to solve this issue, I can offer to write it: for example considering undefined the loopback address or adding an special option for that case.

Thanks!

[dougwilson]

Yea, that's what I'm thinking: to maybe just consider the UNIX socket to be the loopback address. It's probably better solved in the forwarded module, maybe. Since a TCP/IP socket in Node.js cal also return undefined for req.connection.remoteAddress, simply assuming that undefined means socket is not really enough to know that for sure.

[theneva]

Hi! 👋 I believe this issue was fixed in the forwarded module in 0.2.0, which was pulled into this module in 97965bd? Maybe this issue can be closed.

(For posterity, I think this commit fixed the problem: jshttp/forwarded@63a16a6)