package dhcpd import ( "encoding/binary" "fmt" "net" "github.com/AdguardTeam/golibs/log" "github.com/joomcode/errorx" ) func isTimeout(err error) bool { operr, ok := err.(*net.OpError) if !ok { return false } return operr.Timeout() } // 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.Tracef("Got IP that is not IPv4: %v", ipnet.IP) continue } log.Tracef("Got IP that is IPv4: %v", ipnet.IP) return &net.IPNet{ IP: ipnet.IP.To4(), Mask: ipnet.Mask, } } return nil } func wrapErrPrint(err error, message string, args ...interface{}) error { var errx error if err == nil { errx = fmt.Errorf(message, args...) } else { errx = errorx.Decorate(err, message, args...) } log.Println(errx.Error()) return errx } func parseIPv4(text string) (net.IP, error) { result := net.ParseIP(text) if result == nil { return nil, fmt.Errorf("%s is not an IP address", text) } if result.To4() == nil { return nil, fmt.Errorf("%s is not an IPv4 address", text) } return result.To4(), nil } // Return TRUE if subnet mask is correct (e.g. 255.255.255.0) func isValidSubnetMask(mask net.IP) bool { var n uint32 n = binary.BigEndian.Uint32(mask) for i := 0; i != 32; i++ { if n == 0 { break } if (n & 0x80000000) == 0 { return false } n <<= 1 } return true }