Proxy and ip decoder

[getlarge]

Hey,
I'm using this project very often and i noticed that having a nice ipAddress property might be useful for me and other users ( to use in preConnect hook for example ).
Since it's important to have a correct information, i thought it would be interesting to add a trustProxy property to the broker. Then if aedes is placed behind load balancer / proxy, we could use http headers (x-real-ip / x-forwarded-for ) in case of websocket connection or proxy protocol in case of tcp socket.
So i implemented proxy-protocol-js to test incoming client's buffer and to try retrieving source ip address.

I've been adding an example and some tests.

Please let me know if this feature is useful and not out of the scope of aedes.

[mcollina]

Thanks and good work! I've left a few note.

Indeed, it will be a good feature to add.

[mcollina]

Good work!

A couple of things:

1. CI is failing, can you take a look?
2. If the proxy packet is split into two separate chunks, would all this logic work?

[getlarge]

Concerning the CI, i noticed that test failures happened with node v12.13.1 and the same happens locally on my computer and they also appear on the master branch.
For now i don't see where to start debugging, but i will dig into it.

For the split, you think of one chunk containing the proxy protocol and the other containing the mqtt packet ? Before the parsing ?
Currently, this is what happened after proxyProtocol.parse, where the "clean" tcp packet is extracted in the data property of the result, which can be sent to mqttPacket.parser.

[mcollina]

I mean if the proxy protocol header is split into 2 chunks. Are there some guarantees this cannot happen?

[getlarge]

Quote from : https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt
"Both [ proxy protocol v1 and v2] formats are designed to fit in the smallest TCP segment that any TCP/IP host is required to support (576 - 40 = 536 bytes). This ensures that the whole
header will always be delivered at once when the socket buffers are still empty
at the beginning of a connection".

Still it might depend on the proxy configuration i suppose.

There are no guarantee that this cannot happen, so the connection to aedes should be dropped or delayed until the proxy header is complete ?

[mcollina]

Given on that text, I think this is ok and I was worrying for nothing.