package main import ( "net" "os" "os/signal" "syscall" "time" "github.com/AdguardTeam/AdGuardHome/dhcpd" "github.com/hmage/golibs/log" "github.com/krolaw/dhcp4" ) func main() { if len(os.Args) < 2 { log.Printf("Usage: %s ", os.Args[0]) os.Exit(64) } ifaceName := os.Args[1] present, err := dhcpd.CheckIfOtherDHCPServersPresent(ifaceName) if err != nil { panic(err) } log.Printf("Found DHCP server? %v", present) if present { log.Printf("Will not start DHCP server because there's already running one on the network") os.Exit(1) } iface, err := net.InterfaceByName(ifaceName) if err != nil { panic(err) } // get ipv4 address of an interface ifaceIPNet := getIfaceIPv4(iface) if ifaceIPNet == nil { panic(err) } // append 10 to server's IP address as start start := dhcp4.IPAdd(ifaceIPNet.IP, 10) // lease range is 100 IP's, but TODO: don't go beyond end of subnet mask stop := dhcp4.IPAdd(start, 100) server := dhcpd.Server{} config := dhcpd.ServerConfig{ InterfaceName: ifaceName, RangeStart: start.String(), RangeEnd: stop.String(), SubnetMask: "255.255.255.0", GatewayIP: "192.168.7.1", } log.Printf("Starting DHCP server") err = server.Start(&config) if err != nil { panic(err) } time.Sleep(time.Second) log.Printf("Stopping DHCP server") err = server.Stop() if err != nil { panic(err) } log.Printf("Starting DHCP server") err = server.Start(&config) if err != nil { panic(err) } log.Printf("Starting DHCP server while it's already running") err = server.Start(&config) if err != nil { panic(err) } log.Printf("Now serving DHCP") signal_channel := make(chan os.Signal) signal.Notify(signal_channel, syscall.SIGINT, syscall.SIGTERM) <-signal_channel } // return first IPv4 address of an interface, if there is any func getIfaceIPv4(iface *net.Interface) *net.IPNet { ifaceAddrs, err := iface.Addrs() if err != nil { panic(err) } for _, addr := range ifaceAddrs { ipnet, ok := addr.(*net.IPNet) if !ok { // not an IPNet, should not happen log.Fatalf("SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet", addr) } if ipnet.IP.To4() == nil { log.Printf("Got IP that is not IPv4: %v", ipnet.IP) continue } log.Printf("Got IP that is IPv4: %v", ipnet.IP) return &net.IPNet{ IP: ipnet.IP.To4(), Mask: ipnet.Mask, } } return nil }