net/ipv4/helper.go

// Copyright 2012 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ipv4

import (
	"errors"
	"net"
)

var (
	errOpNoSupport              = errors.New("operation not supported")
	errNoSuchInterface          = errors.New("no such interface")
	errNoSuchMulticastInterface = errors.New("no such multicast interface")
)

func boolint(b bool) int {
	if b {
		return 1
	}
	return 0
}

func netAddrToIP4(a net.Addr) net.IP {
	switch v := a.(type) {
	case *net.UDPAddr:
		if ip := v.IP.To4(); ip != nil {
			return ip
		}
	case *net.IPAddr:
		if ip := v.IP.To4(); ip != nil {
			return ip
		}
	}
	return nil
}

func netIP4ToInterface(ip net.IP) (*net.Interface, error) {
	ift, err := net.Interfaces()
	if err != nil {
		return nil, err
	}
	for _, ifi := range ift {
		ifat, err := ifi.Addrs()
		if err != nil {
			return nil, err
		}
		for _, ifa := range ifat {
			switch v := ifa.(type) {
			case *net.IPAddr:
				if ip.Equal(v.IP) {
					return &ifi, nil
				}
			case *net.IPNet:
				if ip.Equal(v.IP) {
					return &ifi, nil
				}
			}
		}
	}
	return nil, errNoSuchInterface
}

func netInterfaceToIP4(ifi *net.Interface) (net.IP, error) {
	if ifi == nil {
		return net.IPv4zero, nil
	}
	ifat, err := ifi.Addrs()
	if err != nil {
		return nil, err
	}
	for _, ifa := range ifat {
		switch v := ifa.(type) {
		case *net.IPAddr:
			if v.IP.To4() != nil {
				return v.IP, nil
			}
		case *net.IPNet:
			if v.IP.To4() != nil {
				return v.IP, nil
			}
		}
	}
	return nil, errNoSuchInterface
}