// Copyright 2014 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.

// +build darwin dragonfly freebsd linux netbsd openbsd solaris

package icmp

import (
	"net"
	"syscall"
)

func sockaddr(family int, address string) (syscall.Sockaddr, error) {
	switch family {
	case syscall.AF_INET:
		a, err := net.ResolveIPAddr("ip4", address)
		if err != nil {
			return nil, err
		}
		if len(a.IP) == 0 {
			a.IP = net.IPv4zero
		}
		if a.IP = a.IP.To4(); a.IP == nil {
			return nil, net.InvalidAddrError("non-ipv4 address")
		}
		sa := &syscall.SockaddrInet4{}
		copy(sa.Addr[:], a.IP)
		return sa, nil
	case syscall.AF_INET6:
		a, err := net.ResolveIPAddr("ip6", address)
		if err != nil {
			return nil, err
		}
		if len(a.IP) == 0 {
			a.IP = net.IPv6unspecified
		}
		if a.IP.Equal(net.IPv4zero) {
			a.IP = net.IPv6unspecified
		}
		if a.IP = a.IP.To16(); a.IP == nil || a.IP.To4() != nil {
			return nil, net.InvalidAddrError("non-ipv6 address")
		}
		sa := &syscall.SockaddrInet6{ZoneId: zoneToUint32(a.Zone)}
		copy(sa.Addr[:], a.IP)
		return sa, nil
	default:
		return nil, net.InvalidAddrError("unexpected family")
	}
}

func zoneToUint32(zone string) uint32 {
	if zone == "" {
		return 0
	}
	if ifi, err := net.InterfaceByName(zone); err == nil {
		return uint32(ifi.Index)
	}
	n, _, _ := dtoi(zone, 0)
	return uint32(n)
}

func last(s string, b byte) int {
	i := len(s)
	for i--; i >= 0; i-- {
		if s[i] == b {
			break
		}
	}
	return i
}

const big = 0xFFFFFF

func dtoi(s string, i0 int) (n int, i int, ok bool) {
	n = 0
	for i = i0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
		n = n*10 + int(s[i]-'0')
		if n >= big {
			return 0, i, false
		}
	}
	if i == i0 {
		return 0, i, false
	}
	return n, i, true
}