lock rpc down

[nick1udwig]

Problem

is_local is not a robust way to determine that an http request is actually local. E.g., a node behind a reverse proxy will believe all http requests it receives are local.

Solution

1. Turn off is_local handling by default. Enable it with the commandline flag expose-local
2. When expose-locald, check for x-forwarded-type headers that reverse proxies commonly put on requests. Caddy puts these headers by default; nginx does not; apache may or may not.

Testing

1. no flag, local
2. yes flag local
3. no flag reverse proxy
4. yes flag reverse proxy

Docs Update

TODO

Notes

None