peerinfo

Grab information about the process of a connected TCP socket.

This allows doing stuff we typically do with unix sockets with programs that do not allow unix sockets.

It's all qemu's fault by the way, see https://bugs.launchpad.net/bugs/1903470

Usage

Calling peerinfo.Find will return details on the process owning the given socket address on the local machine. This is done by reading files in /proc so this library is linux only.

import "github.com/KarpelesLab/peerinfo"

func xxx(c net.Conn) {
	// remote and local are reversed as we want to remote side of the socket
	ci, err := peerinfo.Find(c.RemoteAddr(), c.LocalAddr())
	
	// check err, etc...
}

With Unix sockets?

Go notoriously lacks a way to get the peer's information on a unix socket. As it turns out, an issue was opened in 2010 about this (get SO_PEERCRED information from an open socket), but was hijacked into sending FDs and credentials over unix sockets and the original issue was cast aside for the issue to be finally closed in 2017 without a proper resolution.

Because of this, this package will also provide a method to obtain peer credentials based on a net.UnixConn. Maybe one day Go will have a proper API to perform this.

You can either directly query info with peerinfo.UnixPeer() if you know it will be a unix conn, or let peerinfo detect the type of connection.

import "github.com/KarpelesLab/peerinfo"

func xxx(c net.Conn) {
	// just pass the connection and it'll be automatic
	ci, err := peerinfo.FindPeer(c)
	if err != nil {
		...
	}

	// can use ci.Pid, ci.GetUid(), ci.GetGid()