kdhcp/server/ifi_linux.go

//go:build linux

package server

import (
	"fmt"
	"net"
	"syscall"

	log "git.wntrmute.dev/kyle/goutils/log"
)

func BindInterface(ip net.IP, port int, dev string) (net.PacketConn, error) {
	udpAddr, err := net.ResolveUDPAddr("udp4", fmt.Sprintf(":%d", port))
	if err != nil {
		return nil, err
	}

	log.Debugf("listen on %s", udpAddr)
	conn, err := net.ListenUDP("udp4", udpAddr)
	if err != nil {
		return nil, err
	}

	sysconn, err := conn.SyscallConn()
	if err != nil {
		conn.Close()
		return nil, err
	}

	sysconn.Control(func(fd uintptr) {
		err = syscall.BindToDevice(int(fd), dev)
	})

	if err != nil {
		conn.Close()
		return nil, err
	}

	return conn, nil
}