golang: unix socket: get peer credential

client.go

package main

import (
	"fmt"
	"net"
	"os"
)

func main() {
	addr, _ := net.ResolveUnixAddr("unix", "@testabstractsocket")
	client, err := net.DialUnix("unix", nil, addr)
	if err != nil {
		fmt.Println("Cannot dial", err.Error())
		os.Exit(1)
	}
	defer client.Close()
	fmt.Println("Connected!")
}

server.go

package main

import (
	"fmt"
	"net"
	"os"
	"syscall"
)

func main() {
	addr, _ := net.ResolveUnixAddr("unix", "@testabstractsocket")
	server, err := net.ListenUnix("unix", addr)
	if err != nil {
		fmt.Println("Cannot listen", err.Error())
		os.Exit(1)
	}
	for {
		client, err := server.AcceptUnix()
		if err != nil {
			fmt.Println("Cannot accept", err.Error())
			continue
		}
		go serve(client)
	}
}

func serve(client *net.UnixConn) {
	defer client.Close()
	f, err := client.File()
	if err != nil {
		fmt.Println("Cannot get underlying file", err.Error())
		return
	}
	defer f.Close()
	cred, err := syscall.GetsockoptUcred(int(f.Fd()), syscall.SOL_SOCKET, syscall.SO_PEERCRED)
	if err != nil {
		fmt.Println("Cannot get peer credential", err.Error())
		return
	}
	if cred.Uid == 0 {
		fmt.Println("root client connected, do something dangerous !")
	} else {
		fmt.Println("non-root client connected, do nothing !")
	}
}

Thanks for this! Totally adjacent but a really handy example on how to do socket auth!