679 lines
15 KiB
Go
679 lines
15 KiB
Go
// Copyright 2009 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.
|
|
|
|
// IP address manipulations
|
|
//
|
|
// IPv4 addresses are 4 bytes; IPv6 addresses are 16 bytes.
|
|
// An IPv4 address can be converted to an IPv6 address by
|
|
// adding a canonical prefix (10 zeros, 2 0xFFs).
|
|
// This library accepts either size of byte slice but always
|
|
// returns 16-byte addresses.
|
|
|
|
package net
|
|
|
|
import "errors"
|
|
|
|
// IP address lengths (bytes).
|
|
const (
|
|
IPv4len = 4
|
|
IPv6len = 16
|
|
)
|
|
|
|
// An IP is a single IP address, a slice of bytes.
|
|
// Functions in this package accept either 4-byte (IPv4)
|
|
// or 16-byte (IPv6) slices as input.
|
|
//
|
|
// Note that in this documentation, referring to an
|
|
// IP address as an IPv4 address or an IPv6 address
|
|
// is a semantic property of the address, not just the
|
|
// length of the byte slice: a 16-byte slice can still
|
|
// be an IPv4 address.
|
|
type IP []byte
|
|
|
|
// An IP mask is an IP address.
|
|
type IPMask []byte
|
|
|
|
// An IPNet represents an IP network.
|
|
type IPNet struct {
|
|
IP IP // network number
|
|
Mask IPMask // network mask
|
|
}
|
|
|
|
// IPv4 returns the IP address (in 16-byte form) of the
|
|
// IPv4 address a.b.c.d.
|
|
func IPv4(a, b, c, d byte) IP {
|
|
p := make(IP, IPv6len)
|
|
copy(p, v4InV6Prefix)
|
|
p[12] = a
|
|
p[13] = b
|
|
p[14] = c
|
|
p[15] = d
|
|
return p
|
|
}
|
|
|
|
var v4InV6Prefix = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff}
|
|
|
|
// IPv4Mask returns the IP mask (in 4-byte form) of the
|
|
// IPv4 mask a.b.c.d.
|
|
func IPv4Mask(a, b, c, d byte) IPMask {
|
|
p := make(IPMask, IPv4len)
|
|
p[0] = a
|
|
p[1] = b
|
|
p[2] = c
|
|
p[3] = d
|
|
return p
|
|
}
|
|
|
|
// CIDRMask returns an IPMask consisting of `ones' 1 bits
|
|
// followed by 0s up to a total length of `bits' bits.
|
|
// For a mask of this form, CIDRMask is the inverse of IPMask.Size.
|
|
func CIDRMask(ones, bits int) IPMask {
|
|
if bits != 8*IPv4len && bits != 8*IPv6len {
|
|
return nil
|
|
}
|
|
if ones < 0 || ones > bits {
|
|
return nil
|
|
}
|
|
l := bits / 8
|
|
m := make(IPMask, l)
|
|
n := uint(ones)
|
|
for i := 0; i < l; i++ {
|
|
if n >= 8 {
|
|
m[i] = 0xff
|
|
n -= 8
|
|
continue
|
|
}
|
|
m[i] = ^byte(0xff >> n)
|
|
n = 0
|
|
}
|
|
return m
|
|
}
|
|
|
|
// Well-known IPv4 addresses
|
|
var (
|
|
IPv4bcast = IPv4(255, 255, 255, 255) // broadcast
|
|
IPv4allsys = IPv4(224, 0, 0, 1) // all systems
|
|
IPv4allrouter = IPv4(224, 0, 0, 2) // all routers
|
|
IPv4zero = IPv4(0, 0, 0, 0) // all zeros
|
|
)
|
|
|
|
// Well-known IPv6 addresses
|
|
var (
|
|
IPv6zero = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
|
|
IPv6unspecified = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
|
|
IPv6loopback = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
|
|
IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
|
|
IPv6linklocalallnodes = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
|
|
IPv6linklocalallrouters = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}
|
|
)
|
|
|
|
// IsUnspecified returns true if ip is an unspecified address.
|
|
func (ip IP) IsUnspecified() bool {
|
|
if ip.Equal(IPv4zero) || ip.Equal(IPv6unspecified) {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
// IsLoopback returns true if ip is a loopback address.
|
|
func (ip IP) IsLoopback() bool {
|
|
if ip4 := ip.To4(); ip4 != nil && ip4[0] == 127 {
|
|
return true
|
|
}
|
|
return ip.Equal(IPv6loopback)
|
|
}
|
|
|
|
// IsMulticast returns true if ip is a multicast address.
|
|
func (ip IP) IsMulticast() bool {
|
|
if ip4 := ip.To4(); ip4 != nil && ip4[0]&0xf0 == 0xe0 {
|
|
return true
|
|
}
|
|
return ip[0] == 0xff
|
|
}
|
|
|
|
// IsInterfaceLinkLocalMulticast returns true if ip is
|
|
// an interface-local multicast address.
|
|
func (ip IP) IsInterfaceLocalMulticast() bool {
|
|
return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x01
|
|
}
|
|
|
|
// IsLinkLocalMulticast returns true if ip is a link-local
|
|
// multicast address.
|
|
func (ip IP) IsLinkLocalMulticast() bool {
|
|
if ip4 := ip.To4(); ip4 != nil && ip4[0] == 224 && ip4[1] == 0 && ip4[2] == 0 {
|
|
return true
|
|
}
|
|
return ip[0] == 0xff && ip[1]&0x0f == 0x02
|
|
}
|
|
|
|
// IsLinkLocalUnicast returns true if ip is a link-local
|
|
// unicast address.
|
|
func (ip IP) IsLinkLocalUnicast() bool {
|
|
if ip4 := ip.To4(); ip4 != nil && ip4[0] == 169 && ip4[1] == 254 {
|
|
return true
|
|
}
|
|
return ip[0] == 0xfe && ip[1]&0xc0 == 0x80
|
|
}
|
|
|
|
// IsGlobalUnicast returns true if ip is a global unicast
|
|
// address.
|
|
func (ip IP) IsGlobalUnicast() bool {
|
|
return !ip.IsUnspecified() &&
|
|
!ip.IsLoopback() &&
|
|
!ip.IsMulticast() &&
|
|
!ip.IsLinkLocalUnicast()
|
|
}
|
|
|
|
// Is p all zeros?
|
|
func isZeros(p IP) bool {
|
|
for i := 0; i < len(p); i++ {
|
|
if p[i] != 0 {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// To4 converts the IPv4 address ip to a 4-byte representation.
|
|
// If ip is not an IPv4 address, To4 returns nil.
|
|
func (ip IP) To4() IP {
|
|
if len(ip) == IPv4len {
|
|
return ip
|
|
}
|
|
if len(ip) == IPv6len &&
|
|
isZeros(ip[0:10]) &&
|
|
ip[10] == 0xff &&
|
|
ip[11] == 0xff {
|
|
return ip[12:16]
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// To16 converts the IP address ip to a 16-byte representation.
|
|
// If ip is not an IP address (it is the wrong length), To16 returns nil.
|
|
func (ip IP) To16() IP {
|
|
if len(ip) == IPv4len {
|
|
return IPv4(ip[0], ip[1], ip[2], ip[3])
|
|
}
|
|
if len(ip) == IPv6len {
|
|
return ip
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Default route masks for IPv4.
|
|
var (
|
|
classAMask = IPv4Mask(0xff, 0, 0, 0)
|
|
classBMask = IPv4Mask(0xff, 0xff, 0, 0)
|
|
classCMask = IPv4Mask(0xff, 0xff, 0xff, 0)
|
|
)
|
|
|
|
// DefaultMask returns the default IP mask for the IP address ip.
|
|
// Only IPv4 addresses have default masks; DefaultMask returns
|
|
// nil if ip is not a valid IPv4 address.
|
|
func (ip IP) DefaultMask() IPMask {
|
|
if ip = ip.To4(); ip == nil {
|
|
return nil
|
|
}
|
|
switch true {
|
|
case ip[0] < 0x80:
|
|
return classAMask
|
|
case ip[0] < 0xC0:
|
|
return classBMask
|
|
default:
|
|
return classCMask
|
|
}
|
|
}
|
|
|
|
func allFF(b []byte) bool {
|
|
for _, c := range b {
|
|
if c != 0xff {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Mask returns the result of masking the IP address ip with mask.
|
|
func (ip IP) Mask(mask IPMask) IP {
|
|
if len(mask) == IPv6len && len(ip) == IPv4len && allFF(mask[:12]) {
|
|
mask = mask[12:]
|
|
}
|
|
if len(mask) == IPv4len && len(ip) == IPv6len && bytesEqual(ip[:12], v4InV6Prefix) {
|
|
ip = ip[12:]
|
|
}
|
|
n := len(ip)
|
|
if n != len(mask) {
|
|
return nil
|
|
}
|
|
out := make(IP, n)
|
|
for i := 0; i < n; i++ {
|
|
out[i] = ip[i] & mask[i]
|
|
}
|
|
return out
|
|
}
|
|
|
|
// String returns the string form of the IP address ip.
|
|
// If the address is an IPv4 address, the string representation
|
|
// is dotted decimal ("74.125.19.99"). Otherwise the representation
|
|
// is IPv6 ("2001:4860:0:2001::68").
|
|
func (ip IP) String() string {
|
|
p := ip
|
|
|
|
if len(ip) == 0 {
|
|
return "<nil>"
|
|
}
|
|
|
|
// If IPv4, use dotted notation.
|
|
if p4 := p.To4(); len(p4) == IPv4len {
|
|
return itod(uint(p4[0])) + "." +
|
|
itod(uint(p4[1])) + "." +
|
|
itod(uint(p4[2])) + "." +
|
|
itod(uint(p4[3]))
|
|
}
|
|
if len(p) != IPv6len {
|
|
return "?"
|
|
}
|
|
|
|
// Find longest run of zeros.
|
|
e0 := -1
|
|
e1 := -1
|
|
for i := 0; i < IPv6len; i += 2 {
|
|
j := i
|
|
for j < IPv6len && p[j] == 0 && p[j+1] == 0 {
|
|
j += 2
|
|
}
|
|
if j > i && j-i > e1-e0 {
|
|
e0 = i
|
|
e1 = j
|
|
}
|
|
}
|
|
// The symbol "::" MUST NOT be used to shorten just one 16 bit 0 field.
|
|
if e1-e0 <= 2 {
|
|
e0 = -1
|
|
e1 = -1
|
|
}
|
|
|
|
// Print with possible :: in place of run of zeros
|
|
var s string
|
|
for i := 0; i < IPv6len; i += 2 {
|
|
if i == e0 {
|
|
s += "::"
|
|
i = e1
|
|
if i >= IPv6len {
|
|
break
|
|
}
|
|
} else if i > 0 {
|
|
s += ":"
|
|
}
|
|
s += itox((uint(p[i])<<8)|uint(p[i+1]), 1)
|
|
}
|
|
return s
|
|
}
|
|
|
|
// ipEmptyString is like ip.String except that it returns
|
|
// an empty string when ip is unset.
|
|
func ipEmptyString(ip IP) string {
|
|
if len(ip) == 0 {
|
|
return ""
|
|
}
|
|
return ip.String()
|
|
}
|
|
|
|
// MarshalText implements the encoding.TextMarshaler interface.
|
|
// The encoding is the same as returned by String.
|
|
func (ip IP) MarshalText() ([]byte, error) {
|
|
if len(ip) == 0 {
|
|
return []byte(""), nil
|
|
}
|
|
if len(ip) != IPv4len && len(ip) != IPv6len {
|
|
return nil, errors.New("invalid IP address")
|
|
}
|
|
return []byte(ip.String()), nil
|
|
}
|
|
|
|
// UnmarshalText implements the encoding.TextUnmarshaler interface.
|
|
// The IP address is expected in a form accepted by ParseIP.
|
|
func (ip *IP) UnmarshalText(text []byte) error {
|
|
if len(text) == 0 {
|
|
*ip = nil
|
|
return nil
|
|
}
|
|
s := string(text)
|
|
x := ParseIP(s)
|
|
if x == nil {
|
|
return &ParseError{"IP address", s}
|
|
}
|
|
*ip = x
|
|
return nil
|
|
}
|
|
|
|
// Equal returns true if ip and x are the same IP address.
|
|
// An IPv4 address and that same address in IPv6 form are
|
|
// considered to be equal.
|
|
func (ip IP) Equal(x IP) bool {
|
|
if len(ip) == len(x) {
|
|
return bytesEqual(ip, x)
|
|
}
|
|
if len(ip) == IPv4len && len(x) == IPv6len {
|
|
return bytesEqual(x[0:12], v4InV6Prefix) && bytesEqual(ip, x[12:])
|
|
}
|
|
if len(ip) == IPv6len && len(x) == IPv4len {
|
|
return bytesEqual(ip[0:12], v4InV6Prefix) && bytesEqual(ip[12:], x)
|
|
}
|
|
return false
|
|
}
|
|
|
|
func bytesEqual(x, y []byte) bool {
|
|
if len(x) != len(y) {
|
|
return false
|
|
}
|
|
for i, b := range x {
|
|
if y[i] != b {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// If mask is a sequence of 1 bits followed by 0 bits,
|
|
// return the number of 1 bits.
|
|
func simpleMaskLength(mask IPMask) int {
|
|
var n int
|
|
for i, v := range mask {
|
|
if v == 0xff {
|
|
n += 8
|
|
continue
|
|
}
|
|
// found non-ff byte
|
|
// count 1 bits
|
|
for v&0x80 != 0 {
|
|
n++
|
|
v <<= 1
|
|
}
|
|
// rest must be 0 bits
|
|
if v != 0 {
|
|
return -1
|
|
}
|
|
for i++; i < len(mask); i++ {
|
|
if mask[i] != 0 {
|
|
return -1
|
|
}
|
|
}
|
|
break
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Size returns the number of leading ones and total bits in the mask.
|
|
// If the mask is not in the canonical form--ones followed by zeros--then
|
|
// Size returns 0, 0.
|
|
func (m IPMask) Size() (ones, bits int) {
|
|
ones, bits = simpleMaskLength(m), len(m)*8
|
|
if ones == -1 {
|
|
return 0, 0
|
|
}
|
|
return
|
|
}
|
|
|
|
// String returns the hexadecimal form of m, with no punctuation.
|
|
func (m IPMask) String() string {
|
|
s := ""
|
|
for _, b := range m {
|
|
s += itox(uint(b), 2)
|
|
}
|
|
if len(s) == 0 {
|
|
return "<nil>"
|
|
}
|
|
return s
|
|
}
|
|
|
|
func networkNumberAndMask(n *IPNet) (ip IP, m IPMask) {
|
|
if ip = n.IP.To4(); ip == nil {
|
|
ip = n.IP
|
|
if len(ip) != IPv6len {
|
|
return nil, nil
|
|
}
|
|
}
|
|
m = n.Mask
|
|
switch len(m) {
|
|
case IPv4len:
|
|
if len(ip) != IPv4len {
|
|
return nil, nil
|
|
}
|
|
case IPv6len:
|
|
if len(ip) == IPv4len {
|
|
m = m[12:]
|
|
}
|
|
default:
|
|
return nil, nil
|
|
}
|
|
return
|
|
}
|
|
|
|
// Contains reports whether the network includes ip.
|
|
func (n *IPNet) Contains(ip IP) bool {
|
|
nn, m := networkNumberAndMask(n)
|
|
if x := ip.To4(); x != nil {
|
|
ip = x
|
|
}
|
|
l := len(ip)
|
|
if l != len(nn) {
|
|
return false
|
|
}
|
|
for i := 0; i < l; i++ {
|
|
if nn[i]&m[i] != ip[i]&m[i] {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Network returns the address's network name, "ip+net".
|
|
func (n *IPNet) Network() string { return "ip+net" }
|
|
|
|
// String returns the CIDR notation of n like "192.168.100.1/24"
|
|
// or "2001:DB8::/48" as defined in RFC 4632 and RFC 4291.
|
|
// If the mask is not in the canonical form, it returns the
|
|
// string which consists of an IP address, followed by a slash
|
|
// character and a mask expressed as hexadecimal form with no
|
|
// punctuation like "192.168.100.1/c000ff00".
|
|
func (n *IPNet) String() string {
|
|
nn, m := networkNumberAndMask(n)
|
|
if nn == nil || m == nil {
|
|
return "<nil>"
|
|
}
|
|
l := simpleMaskLength(m)
|
|
if l == -1 {
|
|
return nn.String() + "/" + m.String()
|
|
}
|
|
return nn.String() + "/" + itod(uint(l))
|
|
}
|
|
|
|
// Parse IPv4 address (d.d.d.d).
|
|
func parseIPv4(s string) IP {
|
|
var p [IPv4len]byte
|
|
i := 0
|
|
for j := 0; j < IPv4len; j++ {
|
|
if i >= len(s) {
|
|
// Missing octets.
|
|
return nil
|
|
}
|
|
if j > 0 {
|
|
if s[i] != '.' {
|
|
return nil
|
|
}
|
|
i++
|
|
}
|
|
var (
|
|
n int
|
|
ok bool
|
|
)
|
|
n, i, ok = dtoi(s, i)
|
|
if !ok || n > 0xFF {
|
|
return nil
|
|
}
|
|
p[j] = byte(n)
|
|
}
|
|
if i != len(s) {
|
|
return nil
|
|
}
|
|
return IPv4(p[0], p[1], p[2], p[3])
|
|
}
|
|
|
|
// parseIPv6 parses s as a literal IPv6 address described in RFC 4291
|
|
// and RFC 5952. It can also parse a literal scoped IPv6 address with
|
|
// zone identifier which is described in RFC 4007 when zoneAllowed is
|
|
// true.
|
|
func parseIPv6(s string, zoneAllowed bool) (ip IP, zone string) {
|
|
ip = make(IP, IPv6len)
|
|
ellipsis := -1 // position of ellipsis in p
|
|
i := 0 // index in string s
|
|
|
|
if zoneAllowed {
|
|
s, zone = splitHostZone(s)
|
|
}
|
|
|
|
// Might have leading ellipsis
|
|
if len(s) >= 2 && s[0] == ':' && s[1] == ':' {
|
|
ellipsis = 0
|
|
i = 2
|
|
// Might be only ellipsis
|
|
if i == len(s) {
|
|
return ip, zone
|
|
}
|
|
}
|
|
|
|
// Loop, parsing hex numbers followed by colon.
|
|
j := 0
|
|
for j < IPv6len {
|
|
// Hex number.
|
|
n, i1, ok := xtoi(s, i)
|
|
if !ok || n > 0xFFFF {
|
|
return nil, zone
|
|
}
|
|
|
|
// If followed by dot, might be in trailing IPv4.
|
|
if i1 < len(s) && s[i1] == '.' {
|
|
if ellipsis < 0 && j != IPv6len-IPv4len {
|
|
// Not the right place.
|
|
return nil, zone
|
|
}
|
|
if j+IPv4len > IPv6len {
|
|
// Not enough room.
|
|
return nil, zone
|
|
}
|
|
ip4 := parseIPv4(s[i:])
|
|
if ip4 == nil {
|
|
return nil, zone
|
|
}
|
|
ip[j] = ip4[12]
|
|
ip[j+1] = ip4[13]
|
|
ip[j+2] = ip4[14]
|
|
ip[j+3] = ip4[15]
|
|
i = len(s)
|
|
j += IPv4len
|
|
break
|
|
}
|
|
|
|
// Save this 16-bit chunk.
|
|
ip[j] = byte(n >> 8)
|
|
ip[j+1] = byte(n)
|
|
j += 2
|
|
|
|
// Stop at end of string.
|
|
i = i1
|
|
if i == len(s) {
|
|
break
|
|
}
|
|
|
|
// Otherwise must be followed by colon and more.
|
|
if s[i] != ':' || i+1 == len(s) {
|
|
return nil, zone
|
|
}
|
|
i++
|
|
|
|
// Look for ellipsis.
|
|
if s[i] == ':' {
|
|
if ellipsis >= 0 { // already have one
|
|
return nil, zone
|
|
}
|
|
ellipsis = j
|
|
if i++; i == len(s) { // can be at end
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
// Must have used entire string.
|
|
if i != len(s) {
|
|
return nil, zone
|
|
}
|
|
|
|
// If didn't parse enough, expand ellipsis.
|
|
if j < IPv6len {
|
|
if ellipsis < 0 {
|
|
return nil, zone
|
|
}
|
|
n := IPv6len - j
|
|
for k := j - 1; k >= ellipsis; k-- {
|
|
ip[k+n] = ip[k]
|
|
}
|
|
for k := ellipsis + n - 1; k >= ellipsis; k-- {
|
|
ip[k] = 0
|
|
}
|
|
}
|
|
return ip, zone
|
|
}
|
|
|
|
// A ParseError represents a malformed text string and the type of string that was expected.
|
|
type ParseError struct {
|
|
Type string
|
|
Text string
|
|
}
|
|
|
|
func (e *ParseError) Error() string {
|
|
return "invalid " + e.Type + ": " + e.Text
|
|
}
|
|
|
|
// ParseIP parses s as an IP address, returning the result.
|
|
// The string s can be in dotted decimal ("74.125.19.99")
|
|
// or IPv6 ("2001:4860:0:2001::68") form.
|
|
// If s is not a valid textual representation of an IP address,
|
|
// ParseIP returns nil.
|
|
func ParseIP(s string) IP {
|
|
if ip := parseIPv4(s); ip != nil {
|
|
return ip
|
|
}
|
|
ip, _ := parseIPv6(s, false)
|
|
return ip
|
|
}
|
|
|
|
// ParseCIDR parses s as a CIDR notation IP address and mask,
|
|
// like "192.168.100.1/24" or "2001:DB8::/48", as defined in
|
|
// RFC 4632 and RFC 4291.
|
|
//
|
|
// It returns the IP address and the network implied by the IP
|
|
// and mask. For example, ParseCIDR("192.168.100.1/16") returns
|
|
// the IP address 192.168.100.1 and the network 192.168.0.0/16.
|
|
func ParseCIDR(s string) (IP, *IPNet, error) {
|
|
i := byteIndex(s, '/')
|
|
if i < 0 {
|
|
return nil, nil, &ParseError{"CIDR address", s}
|
|
}
|
|
addr, mask := s[:i], s[i+1:]
|
|
iplen := IPv4len
|
|
ip := parseIPv4(addr)
|
|
if ip == nil {
|
|
iplen = IPv6len
|
|
ip, _ = parseIPv6(addr, false)
|
|
}
|
|
n, i, ok := dtoi(mask, 0)
|
|
if ip == nil || !ok || i != len(mask) || n < 0 || n > 8*iplen {
|
|
return nil, nil, &ParseError{"CIDR address", s}
|
|
}
|
|
m := CIDRMask(n, 8*iplen)
|
|
return ip, &IPNet{IP: ip.Mask(m), Mask: m}, nil
|
|
}
|