package util import ( "errors" "fmt" "net" "os" "runtime" "strconv" "syscall" "time" "github.com/AdguardTeam/golibs/log" ) // NetInterface represents a list of network interfaces type NetInterface struct { Name string // Network interface name MTU int // MTU HardwareAddr string // Hardware address Addresses []string // Array with the network interface addresses Subnets []string // Array with CIDR addresses of this network interface Flags string // Network interface flags (up, broadcast, etc) } // GetValidNetInterfaces returns interfaces that are eligible for DNS and/or DHCP // invalid interface is a ppp interface or the one that doesn't allow broadcasts func GetValidNetInterfaces() ([]net.Interface, error) { ifaces, err := net.Interfaces() if err != nil { return nil, fmt.Errorf("couldn't get list of interfaces: %w", err) } netIfaces := []net.Interface{} netIfaces = append(netIfaces, ifaces...) return netIfaces, nil } // GetValidNetInterfacesForWeb returns interfaces that are eligible for DNS and WEB only // we do not return link-local addresses here func GetValidNetInterfacesForWeb() ([]NetInterface, error) { ifaces, err := GetValidNetInterfaces() if err != nil { return nil, fmt.Errorf("couldn't get interfaces: %w", err) } if len(ifaces) == 0 { return nil, errors.New("couldn't find any legible interface") } var netInterfaces []NetInterface for _, iface := range ifaces { addrs, err := iface.Addrs() if err != nil { return nil, fmt.Errorf("failed to get addresses for interface %s: %w", iface.Name, err) } netIface := NetInterface{ Name: iface.Name, MTU: iface.MTU, HardwareAddr: iface.HardwareAddr.String(), } if iface.Flags != 0 { netIface.Flags = iface.Flags.String() } // Collect network interface addresses for _, addr := range addrs { ipNet, ok := addr.(*net.IPNet) if !ok { // not an IPNet, should not happen return nil, fmt.Errorf("got iface.Addrs() element %s that is not net.IPNet, it is %T", addr, addr) } // ignore link-local if ipNet.IP.IsLinkLocalUnicast() { continue } netIface.Addresses = append(netIface.Addresses, ipNet.IP.String()) netIface.Subnets = append(netIface.Subnets, ipNet.String()) } // Discard interfaces with no addresses if len(netIface.Addresses) != 0 { netInterfaces = append(netInterfaces, netIface) } } return netInterfaces, nil } // GetInterfaceByIP - Get interface name by its IP address. func GetInterfaceByIP(ip string) string { ifaces, err := GetValidNetInterfacesForWeb() if err != nil { return "" } for _, iface := range ifaces { for _, addr := range iface.Addresses { if ip == addr { return iface.Name } } } return "" } // GetSubnet - Get IP address with netmask for the specified interface // Returns an empty string if it fails to find it func GetSubnet(ifaceName string) string { netIfaces, err := GetValidNetInterfacesForWeb() if err != nil { log.Error("Could not get network interfaces info: %v", err) return "" } for _, netIface := range netIfaces { if netIface.Name == ifaceName && len(netIface.Subnets) > 0 { return netIface.Subnets[0] } } return "" } // CheckPortAvailable - check if TCP port is available func CheckPortAvailable(host string, port int) error { ln, err := net.Listen("tcp", net.JoinHostPort(host, strconv.Itoa(port))) if err != nil { return err } _ = ln.Close() // It seems that net.Listener.Close() doesn't close file descriptors right away. // We wait for some time and hope that this fd will be closed. time.Sleep(100 * time.Millisecond) return nil } // CheckPacketPortAvailable - check if UDP port is available func CheckPacketPortAvailable(host string, port int) error { ln, err := net.ListenPacket("udp", net.JoinHostPort(host, strconv.Itoa(port))) if err != nil { return err } _ = ln.Close() // It seems that net.Listener.Close() doesn't close file descriptors right away. // We wait for some time and hope that this fd will be closed. time.Sleep(100 * time.Millisecond) return err } // ErrorIsAddrInUse - check if error is "address already in use" func ErrorIsAddrInUse(err error) bool { errOpError, ok := err.(*net.OpError) if !ok { return false } errSyscallError, ok := errOpError.Err.(*os.SyscallError) if !ok { return false } errErrno, ok := errSyscallError.Err.(syscall.Errno) if !ok { return false } if runtime.GOOS == "windows" { const WSAEADDRINUSE = 10048 return errErrno == WSAEADDRINUSE } return errErrno == syscall.EADDRINUSE }