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// Copyright 2020 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 netip defines an IP address type that's a small value type.
// Building on that Addr type, the package also defines AddrPort (an
// IP address and a port), and Prefix (an IP address and a bit length
// prefix).
//
// Compared to the net.IP type, this package's Addr type takes less
// memory, is immutable, and is comparable (supports == and being a
// map key).
package netip
import (
"errors"
"math"
"strconv"
"internal/bytealg"
"internal/intern"
"internal/itoa"
)
// Sizes: (64-bit)
// net.IP: 24 byte slice header + {4, 16} = 28 to 40 bytes
// net.IPAddr: 40 byte slice header + {4, 16} = 44 to 56 bytes + zone length
// netip.Addr: 24 bytes (zone is per-name singleton, shared across all users)
// Addr represents an IPv4 or IPv6 address (with or without a scoped
// addressing zone), similar to net.IP or net.IPAddr.
//
// Unlike net.IP or net.IPAddr, Addr is a comparable value
// type (it supports == and can be a map key) and is immutable.
//
// The zero Addr is not a valid IP address.
// Addr{} is distinct from both 0.0.0.0 and ::.
type Addr struct {
// addr is the hi and lo bits of an IPv6 address. If z==z4,
// hi and lo contain the IPv4-mapped IPv6 address.
//
// hi and lo are constructed by interpreting a 16-byte IPv6
// address as a big-endian 128-bit number. The most significant
// bits of that number go into hi, the rest into lo.
//
// For example, 0011:2233:4455:6677:8899:aabb:ccdd:eeff is stored as:
// addr.hi = 0x0011223344556677
// addr.lo = 0x8899aabbccddeeff
//
// We store IPs like this, rather than as [16]byte, because it
// turns most operations on IPs into arithmetic and bit-twiddling
// operations on 64-bit registers, which is much faster than
// bytewise processing.
addr uint128
// z is a combination of the address family and the IPv6 zone.
//
// nil means invalid IP address (for a zero Addr).
// z4 means an IPv4 address.
// z6noz means an IPv6 address without a zone.
//
// Otherwise it's the interned zone name string.
z *intern.Value
}
// z0, z4, and z6noz are sentinel IP.z values.
// See the IP type's field docs.
var (
z0 = (*intern.Value)(nil)
z4 = new(intern.Value)
z6noz = new(intern.Value)
)
// IPv6LinkLocalAllNodes returns the IPv6 link-local all nodes multicast
// address ff02::1.
func IPv6LinkLocalAllNodes() Addr { return AddrFrom16([16]byte{0: 0xff, 1: 0x02, 15: 0x01}) }
// IPv6Unspecified returns the IPv6 unspecified address "::".
func IPv6Unspecified() Addr { return Addr{z: z6noz} }
// IPv4Unspecified returns the IPv4 unspecified address "0.0.0.0".
func IPv4Unspecified() Addr { return AddrFrom4([4]byte{}) }
// AddrFrom4 returns the address of the IPv4 address given by the bytes in addr.
func AddrFrom4(addr [4]byte) Addr {
return Addr{
addr: uint128{0, 0xffff00000000 | uint64(addr[0])<<24 | uint64(addr[1])<<16 | uint64(addr[2])<<8 | uint64(addr[3])},
z: z4,
}
}
// AddrFrom16 returns the IPv6 address given by the bytes in addr.
// An IPv4-mapped IPv6 address is left as an IPv6 address.
// (Use Unmap to convert them if needed.)
func AddrFrom16(addr [16]byte) Addr {
return Addr{
addr: uint128{
beUint64(addr[:8]),
beUint64(addr[8:]),
},
z: z6noz,
}
}
// ipv6Slice is like IPv6Raw, but operates on a 16-byte slice. Assumes
// slice is 16 bytes, caller must enforce this.
func ipv6Slice(addr []byte) Addr {
return Addr{
addr: uint128{
beUint64(addr[:8]),
beUint64(addr[8:]),
},
z: z6noz,
}
}
// ParseAddr parses s as an IP address, returning the result. The string
// s can be in dotted decimal ("192.0.2.1"), IPv6 ("2001:db8::68"),
// or IPv6 with a scoped addressing zone ("fe80::1cc0:3e8c:119f:c2e1%ens18").
func ParseAddr(s string) (Addr, error) {
for i := 0; i < len(s); i++ {
switch s[i] {
case '.':
return parseIPv4(s)
case ':':
return parseIPv6(s)
case '%':
// Assume that this was trying to be an IPv6 address with
// a zone specifier, but the address is missing.
return Addr{}, parseAddrError{in: s, msg: "missing IPv6 address"}
}
}
return Addr{}, parseAddrError{in: s, msg: "unable to parse IP"}
}
// MustParseAddr calls ParseAddr(s) and panics on error.
// It is intended for use in tests with hard-coded strings.
func MustParseAddr(s string) Addr {
ip, err := ParseAddr(s)
if err != nil {
panic(err)
}
return ip
}
type parseAddrError struct {
in string // the string given to ParseAddr
msg string // an explanation of the parse failure
at string // optionally, the unparsed portion of in at which the error occurred.
}
func (err parseAddrError) Error() string {
q := strconv.Quote
if err.at != "" {
return "ParseAddr(" + q(err.in) + "): " + err.msg + " (at " + q(err.at) + ")"
}
return "ParseAddr(" + q(err.in) + "): " + err.msg
}
// parseIPv4 parses s as an IPv4 address (in form "192.168.0.1").
func parseIPv4(s string) (ip Addr, err error) {
var fields [4]uint8
var val, pos int
var digLen int // number of digits in current octet
for i := 0; i < len(s); i++ {
if s[i] >= '0' && s[i] <= '9' {
if digLen == 1 && val == 0 {
return Addr{}, parseAddrError{in: s, msg: "IPv4 field has octet with leading zero"}
}
val = val*10 + int(s[i]) - '0'
digLen++
if val > 255 {
return Addr{}, parseAddrError{in: s, msg: "IPv4 field has value >255"}
}
} else if s[i] == '.' {
// .1.2.3
// 1.2.3.
// 1..2.3
if i == 0 || i == len(s)-1 || s[i-1] == '.' {
return Addr{}, parseAddrError{in: s, msg: "IPv4 field must have at least one digit", at: s[i:]}
}
// 1.2.3.4.5
if pos == 3 {
return Addr{}, parseAddrError{in: s, msg: "IPv4 address too long"}
}
fields[pos] = uint8(val)
pos++
val = 0
digLen = 0
} else {
return Addr{}, parseAddrError{in: s, msg: "unexpected character", at: s[i:]}
}
}
if pos < 3 {
return Addr{}, parseAddrError{in: s, msg: "IPv4 address too short"}
}
fields[3] = uint8(val)
return AddrFrom4(fields), nil
}
// parseIPv6 parses s as an IPv6 address (in form "2001:db8::68").
func parseIPv6(in string) (Addr, error) {
s := in
// Split off the zone right from the start. Yes it's a second scan
// of the string, but trying to handle it inline makes a bunch of
// other inner loop conditionals more expensive, and it ends up
// being slower.
zone := ""
i := bytealg.IndexByteString(s, '%')
if i != -1 {
s, zone = s[:i], s[i+1:]
if zone == "" {
// Not allowed to have an empty zone if explicitly specified.
return Addr{}, parseAddrError{in: in, msg: "zone must be a non-empty string"}
}
}
var ip [16]byte
ellipsis := -1 // position of ellipsis in ip
// Might have leading ellipsis
if len(s) >= 2 && s[0] == ':' && s[1] == ':' {
ellipsis = 0
s = s[2:]
// Might be only ellipsis
if len(s) == 0 {
return IPv6Unspecified().WithZone(zone), nil
}
}
// Loop, parsing hex numbers followed by colon.
i = 0
for i < 16 {
// Hex number. Similar to parseIPv4, inlining the hex number
// parsing yields a significant performance increase.
off := 0
acc := uint32(0)
for ; off < len(s); off++ {
c := s[off]
if c >= '0' && c <= '9' {
acc = (acc << 4) + uint32(c-'0')
} else if c >= 'a' && c <= 'f' {
acc = (acc << 4) + uint32(c-'a'+10)
} else if c >= 'A' && c <= 'F' {
acc = (acc << 4) + uint32(c-'A'+10)
} else {
break
}
if acc > math.MaxUint16 {
// Overflow, fail.
return Addr{}, parseAddrError{in: in, msg: "IPv6 field has value >=2^16", at: s}
}
}
if off == 0 {
// No digits found, fail.
return Addr{}, parseAddrError{in: in, msg: "each colon-separated field must have at least one digit", at: s}
}
// If followed by dot, might be in trailing IPv4.
if off < len(s) && s[off] == '.' {
if ellipsis < 0 && i != 12 {
// Not the right place.
return Addr{}, parseAddrError{in: in, msg: "embedded IPv4 address must replace the final 2 fields of the address", at: s}
}
if i+4 > 16 {
// Not enough room.
return Addr{}, parseAddrError{in: in, msg: "too many hex fields to fit an embedded IPv4 at the end of the address", at: s}
}
// TODO: could make this a bit faster by having a helper
// that parses to a [4]byte, and have both parseIPv4 and
// parseIPv6 use it.
ip4, err := parseIPv4(s)
if err != nil {
return Addr{}, parseAddrError{in: in, msg: err.Error(), at: s}
}
ip[i] = ip4.v4(0)
ip[i+1] = ip4.v4(1)
ip[i+2] = ip4.v4(2)
ip[i+3] = ip4.v4(3)
s = ""
i += 4
break
}
// Save this 16-bit chunk.
ip[i] = byte(acc >> 8)
ip[i+1] = byte(acc)
i += 2
// Stop at end of string.
s = s[off:]
if len(s) == 0 {
break
}
// Otherwise must be followed by colon and more.
if s[0] != ':' {
return Addr{}, parseAddrError{in: in, msg: "unexpected character, want colon", at: s}
} else if len(s) == 1 {
return Addr{}, parseAddrError{in: in, msg: "colon must be followed by more characters", at: s}
}
s = s[1:]
// Look for ellipsis.
if s[0] == ':' {
if ellipsis >= 0 { // already have one
return Addr{}, parseAddrError{in: in, msg: "multiple :: in address", at: s}
}
ellipsis = i
s = s[1:]
if len(s) == 0 { // can be at end
break
}
}
}
// Must have used entire string.
if len(s) != 0 {
return Addr{}, parseAddrError{in: in, msg: "trailing garbage after address", at: s}
}
// If didn't parse enough, expand ellipsis.
if i < 16 {
if ellipsis < 0 {
return Addr{}, parseAddrError{in: in, msg: "address string too short"}
}
n := 16 - i
for j := i - 1; j >= ellipsis; j-- {
ip[j+n] = ip[j]
}
for j := ellipsis + n - 1; j >= ellipsis; j-- {
ip[j] = 0
}
} else if ellipsis >= 0 {
// Ellipsis must represent at least one 0 group.
return Addr{}, parseAddrError{in: in, msg: "the :: must expand to at least one field of zeros"}
}
return AddrFrom16(ip).WithZone(zone), nil
}
// AddrFromSlice parses the 4- or 16-byte byte slice as an IPv4 or IPv6 address.
// Note that a net.IP can be passed directly as the []byte argument.
// If slice's length is not 4 or 16, AddrFromSlice returns Addr{}, false.
func AddrFromSlice(slice []byte) (ip Addr, ok bool) {
switch len(slice) {
case 4:
return AddrFrom4(*(*[4]byte)(slice)), true
case 16:
return ipv6Slice(slice), true
}
return Addr{}, false
}
// v4 returns the i'th byte of ip. If ip is not an IPv4, v4 returns
// unspecified garbage.
func (ip Addr) v4(i uint8) uint8 {
return uint8(ip.addr.lo >> ((3 - i) * 8))
}
// v6 returns the i'th byte of ip. If ip is an IPv4 address, this
// accesses the IPv4-mapped IPv6 address form of the IP.
func (ip Addr) v6(i uint8) uint8 {
return uint8(*(ip.addr.halves()[(i/8)%2]) >> ((7 - i%8) * 8))
}
// v6u16 returns the i'th 16-bit word of ip. If ip is an IPv4 address,
// this accesses the IPv4-mapped IPv6 address form of the IP.
func (ip Addr) v6u16(i uint8) uint16 {
return uint16(*(ip.addr.halves()[(i/4)%2]) >> ((3 - i%4) * 16))
}
// isZero reports whether ip is the zero value of the IP type.
// The zero value is not a valid IP address of any type.
//
// Note that "0.0.0.0" and "::" are not the zero value. Use IsUnspecified to
// check for these values instead.
func (ip Addr) isZero() bool {
// Faster than comparing ip == Addr{}, but effectively equivalent,
// as there's no way to make an IP with a nil z from this package.
return ip.z == z0
}
// IsValid reports whether the Addr is an initialized address (not the zero Addr).
//
// Note that "0.0.0.0" and "::" are both valid values.
func (ip Addr) IsValid() bool { return ip.z != z0 }
// BitLen returns the number of bits in the IP address:
// 128 for IPv6, 32 for IPv4, and 0 for the zero Addr.
//
// Note that IPv4-mapped IPv6 addresses are considered IPv6 addresses
// and therefore have bit length 128.
func (ip Addr) BitLen() int {
switch ip.z {
case z0:
return 0
case z4:
return 32
}
return 128
}
// Zone returns ip's IPv6 scoped addressing zone, if any.
func (ip Addr) Zone() string {
if ip.z == nil {
return ""
}
zone, _ := ip.z.Get().(string)
return zone
}
// Compare returns an integer comparing two IPs.
// The result will be 0 if ip == ip2, -1 if ip < ip2, and +1 if ip > ip2.
// The definition of "less than" is the same as the Less method.
func (ip Addr) Compare(ip2 Addr) int {
f1, f2 := ip.BitLen(), ip2.BitLen()
if f1 < f2 {
return -1
}
if f1 > f2 {
return 1
}
hi1, hi2 := ip.addr.hi, ip2.addr.hi
if hi1 < hi2 {
return -1
}
if hi1 > hi2 {
return 1
}
lo1, lo2 := ip.addr.lo, ip2.addr.lo
if lo1 < lo2 {
return -1
}
if lo1 > lo2 {
return 1
}
if ip.Is6() {
za, zb := ip.Zone(), ip2.Zone()
if za < zb {
return -1
}
if za > zb {
return 1
}
}
return 0
}
// Less reports whether ip sorts before ip2.
// IP addresses sort first by length, then their address.
// IPv6 addresses with zones sort just after the same address without a zone.
func (ip Addr) Less(ip2 Addr) bool { return ip.Compare(ip2) == -1 }
func (ip Addr) lessOrEq(ip2 Addr) bool { return ip.Compare(ip2) <= 0 }
// Is4 reports whether ip is an IPv4 address.
//
// It returns false for IPv4-mapped IPv6 addresses. See IP.Unmap.
func (ip Addr) Is4() bool {
return ip.z == z4
}
// Is4In6 reports whether ip is an IPv4-mapped IPv6 address.
func (ip Addr) Is4In6() bool {
return ip.Is6() && ip.addr.hi == 0 && ip.addr.lo>>32 == 0xffff
}
// Is6 reports whether ip is an IPv6 address, including IPv4-mapped
// IPv6 addresses.
func (ip Addr) Is6() bool {
return ip.z != z0 && ip.z != z4
}
// Unmap returns ip with any IPv4-mapped IPv6 address prefix removed.
//
// That is, if ip is an IPv6 address wrapping an IPv4 adddress, it
// returns the wrapped IPv4 address. Otherwise it returns ip unmodified.
func (ip Addr) Unmap() Addr {
if ip.Is4In6() {
ip.z = z4
}
return ip
}
// WithZone returns an IP that's the same as ip but with the provided
// zone. If zone is empty, the zone is removed. If ip is an IPv4
// address, WithZone is a no-op and returns ip unchanged.
func (ip Addr) WithZone(zone string) Addr {
if !ip.Is6() {
return ip
}
if zone == "" {
ip.z = z6noz
return ip
}
ip.z = intern.GetByString(zone)
return ip
}
// withoutZone unconditionally strips the zone from IP.
// It's similar to WithZone, but small enough to be inlinable.
func (ip Addr) withoutZone() Addr {
if !ip.Is6() {
return ip
}
ip.z = z6noz
return ip
}
// hasZone reports whether IP has an IPv6 zone.
func (ip Addr) hasZone() bool {
return ip.z != z0 && ip.z != z4 && ip.z != z6noz
}
// IsLinkLocalUnicast reports whether ip is a link-local unicast address.
func (ip Addr) IsLinkLocalUnicast() bool {
// Dynamic Configuration of IPv4 Link-Local Addresses
// https://datatracker.ietf.org/doc/html/rfc3927#section-2.1
if ip.Is4() {
return ip.v4(0) == 169 && ip.v4(1) == 254
}
// IP Version 6 Addressing Architecture (2.4 Address Type Identification)
// https://datatracker.ietf.org/doc/html/rfc4291#section-2.4
if ip.Is6() {
return ip.v6u16(0)&0xffc0 == 0xfe80
}
return false // zero value
}
// IsLoopback reports whether ip is a loopback address.
func (ip Addr) IsLoopback() bool {
// Requirements for Internet Hosts -- Communication Layers (3.2.1.3 Addressing)
// https://datatracker.ietf.org/doc/html/rfc1122#section-3.2.1.3
if ip.Is4() {
return ip.v4(0) == 127
}
// IP Version 6 Addressing Architecture (2.4 Address Type Identification)
// https://datatracker.ietf.org/doc/html/rfc4291#section-2.4
if ip.Is6() {
return ip.addr.hi == 0 && ip.addr.lo == 1
}
return false // zero value
}
// IsMulticast reports whether ip is a multicast address.
func (ip Addr) IsMulticast() bool {
// Host Extensions for IP Multicasting (4. HOST GROUP ADDRESSES)
// https://datatracker.ietf.org/doc/html/rfc1112#section-4
if ip.Is4() {
return ip.v4(0)&0xf0 == 0xe0
}
// IP Version 6 Addressing Architecture (2.4 Address Type Identification)
// https://datatracker.ietf.org/doc/html/rfc4291#section-2.4
if ip.Is6() {
return ip.addr.hi>>(64-8) == 0xff // ip.v6(0) == 0xff
}
return false // zero value
}
// IsInterfaceLocalMulticast reports whether ip is an IPv6 interface-local
// multicast address.
func (ip Addr) IsInterfaceLocalMulticast() bool {
// IPv6 Addressing Architecture (2.7.1. Pre-Defined Multicast Addresses)
// https://datatracker.ietf.org/doc/html/rfc4291#section-2.7.1
if ip.Is6() {
return ip.v6u16(0)&0xff0f == 0xff01
}
return false // zero value
}
// IsLinkLocalMulticast reports whether ip is a link-local multicast address.
func (ip Addr) IsLinkLocalMulticast() bool {
// IPv4 Multicast Guidelines (4. Local Network Control Block (224.0.0/24))
// https://datatracker.ietf.org/doc/html/rfc5771#section-4
if ip.Is4() {
return ip.v4(0) == 224 && ip.v4(1) == 0 && ip.v4(2) == 0
}
// IPv6 Addressing Architecture (2.7.1. Pre-Defined Multicast Addresses)
// https://datatracker.ietf.org/doc/html/rfc4291#section-2.7.1
if ip.Is6() {
return ip.v6u16(0)&0xff0f == 0xff02
}
return false // zero value
}
// IsGlobalUnicast reports whether ip is a global unicast address.
//
// It returns true for IPv6 addresses which fall outside of the current
// IANA-allocated 2000::/3 global unicast space, with the exception of the
// link-local address space. It also returns true even if ip is in the IPv4
// private address space or IPv6 unique local address space.
// It returns false for the zero Addr.
//
// For reference, see RFC 1122, RFC 4291, and RFC 4632.
func (ip Addr) IsGlobalUnicast() bool {
if ip.z == z0 {
// Invalid or zero-value.
return false
}
// Match package net's IsGlobalUnicast logic. Notably private IPv4 addresses
// and ULA IPv6 addresses are still considered "global unicast".
if ip.Is4() && (ip == IPv4Unspecified() || ip == AddrFrom4([4]byte{255, 255, 255, 255})) {
return false
}
return ip != IPv6Unspecified() &&
!ip.IsLoopback() &&
!ip.IsMulticast() &&
!ip.IsLinkLocalUnicast()
}
// IsPrivate reports whether ip is a private address, according to RFC 1918
// (IPv4 addresses) and RFC 4193 (IPv6 addresses). That is, it reports whether
// ip is in 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, or fc00::/7. This is the
// same as net.IP.IsPrivate.
func (ip Addr) IsPrivate() bool {
// Match the stdlib's IsPrivate logic.
if ip.Is4() {
// RFC 1918 allocates 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 as
// private IPv4 address subnets.
return ip.v4(0) == 10 ||
(ip.v4(0) == 172 && ip.v4(1)&0xf0 == 16) ||
(ip.v4(0) == 192 && ip.v4(1) == 168)
}
if ip.Is6() {
// RFC 4193 allocates fc00::/7 as the unique local unicast IPv6 address
// subnet.
return ip.v6(0)&0xfe == 0xfc
}
return false // zero value
}
// IsUnspecified reports whether ip is an unspecified address, either the IPv4
// address "0.0.0.0" or the IPv6 address "::".
//
// Note that the zero Addr is not an unspecified address.
func (ip Addr) IsUnspecified() bool {
return ip == IPv4Unspecified() || ip == IPv6Unspecified()
}
// Prefix keeps only the top b bits of IP, producing a Prefix
// of the specified length.
// If ip is a zero Addr, Prefix always returns a zero Prefix and a nil error.
// Otherwise, if bits is less than zero or greater than ip.BitLen(),
// Prefix returns an error.
func (ip Addr) Prefix(b int) (Prefix, error) {
if b < 0 {
return Prefix{}, errors.New("negative Prefix bits")
}
effectiveBits := b
switch ip.z {
case z0:
return Prefix{}, nil
case z4:
if b > 32 {
return Prefix{}, errors.New("prefix length " + itoa.Itoa(b) + " too large for IPv4")
}
effectiveBits += 96
default:
if b > 128 {
return Prefix{}, errors.New("prefix length " + itoa.Itoa(b) + " too large for IPv6")
}
}
ip.addr = ip.addr.and(mask6(effectiveBits))
return PrefixFrom(ip, b), nil
}
const (
netIPv4len = 4
netIPv6len = 16
)
// As16 returns the IP address in its 16-byte representation.
// IPv4 addresses are returned as IPv4-mapped IPv6 addresses.
// IPv6 addresses with zones are returned without their zone (use the
// Zone method to get it).
// The ip zero value returns all zeroes.
func (ip Addr) As16() (a16 [16]byte) {
bePutUint64(a16[:8], ip.addr.hi)
bePutUint64(a16[8:], ip.addr.lo)
return a16
}
// As4 returns an IPv4 or IPv4-in-IPv6 address in its 4-byte representation.
// If ip is the zero Addr or an IPv6 address, As4 panics.
// Note that 0.0.0.0 is not the zero Addr.
func (ip Addr) As4() (a4 [4]byte) {
if ip.z == z4 || ip.Is4In6() {
bePutUint32(a4[:], uint32(ip.addr.lo))
return a4
}
if ip.z == z0 {
panic("As4 called on IP zero value")
}
panic("As4 called on IPv6 address")
}
// AsSlice returns an IPv4 or IPv6 address in its respective 4-byte or 16-byte representation.
func (ip Addr) AsSlice() []byte {
switch ip.z {
case z0:
return nil
case z4:
var ret [4]byte
bePutUint32(ret[:], uint32(ip.addr.lo))
return ret[:]
default:
var ret [16]byte
bePutUint64(ret[:8], ip.addr.hi)
bePutUint64(ret[8:], ip.addr.lo)
return ret[:]
}
}
// Next returns the address following ip.
// If there is none, it returns the zero Addr.
func (ip Addr) Next() Addr {
ip.addr = ip.addr.addOne()
if ip.Is4() {
if uint32(ip.addr.lo) == 0 {
// Overflowed.
return Addr{}
}
} else {
if ip.addr.isZero() {
// Overflowed
return Addr{}
}
}
return ip
}
// Prev returns the IP before ip.
// If there is none, it returns the IP zero value.
func (ip Addr) Prev() Addr {
if ip.Is4() {
if uint32(ip.addr.lo) == 0 {
return Addr{}
}
} else if ip.addr.isZero() {
return Addr{}
}
ip.addr = ip.addr.subOne()
return ip
}
// String returns the string form of the IP address ip.
// It returns one of 5 forms:
//
// - "invalid IP", if ip is the zero Addr
// - IPv4 dotted decimal ("192.0.2.1")
// - IPv6 ("2001:db8::1")
// - "::ffff:1.2.3.4" (if Is4In6)
// - IPv6 with zone ("fe80:db8::1%eth0")
//
// Note that unlike package net's IP.String method,
// IPv4-mapped IPv6 addresses format with a "::ffff:"
// prefix before the dotted quad.
func (ip Addr) String() string {
switch ip.z {
case z0:
return "invalid IP"
case z4:
return ip.string4()
default:
if ip.Is4In6() {
// TODO(bradfitz): this could alloc less.
if z := ip.Zone(); z != "" {
return "::ffff:" + ip.Unmap().String() + "%" + z
} else {
return "::ffff:" + ip.Unmap().String()
}
}
return ip.string6()
}
}
// AppendTo appends a text encoding of ip,
// as generated by MarshalText,
// to b and returns the extended buffer.
func (ip Addr) AppendTo(b []byte) []byte {
switch ip.z {
case z0:
return b
case z4:
return ip.appendTo4(b)
default:
if ip.Is4In6() {
b = append(b, "::ffff:"...)
b = ip.Unmap().appendTo4(b)
if z := ip.Zone(); z != "" {
b = append(b, '%')
b = append(b, z...)
}
return b
}
return ip.appendTo6(b)
}
}
// digits is a string of the hex digits from 0 to f. It's used in
// appendDecimal and appendHex to format IP addresses.
const digits = "0123456789abcdef"
// appendDecimal appends the decimal string representation of x to b.
func appendDecimal(b []byte, x uint8) []byte {
// Using this function rather than strconv.AppendUint makes IPv4
// string building 2x faster.
if x >= 100 {
b = append(b, digits[x/100])
}
if x >= 10 {
b = append(b, digits[x/10%10])
}
return append(b, digits[x%10])
}
// appendHex appends the hex string representation of x to b.
func appendHex(b []byte, x uint16) []byte {
// Using this function rather than strconv.AppendUint makes IPv6
// string building 2x faster.
if x >= 0x1000 {
b = append(b, digits[x>>12])
}
if x >= 0x100 {
b = append(b, digits[x>>8&0xf])
}
if x >= 0x10 {
b = append(b, digits[x>>4&0xf])
}
return append(b, digits[x&0xf])
}
// appendHexPad appends the fully padded hex string representation of x to b.
func appendHexPad(b []byte, x uint16) []byte {
return append(b, digits[x>>12], digits[x>>8&0xf], digits[x>>4&0xf], digits[x&0xf])
}
func (ip Addr) string4() string {
const max = len("255.255.255.255")
ret := make([]byte, 0, max)
ret = ip.appendTo4(ret)
return string(ret)
}
func (ip Addr) appendTo4(ret []byte) []byte {
ret = appendDecimal(ret, ip.v4(0))
ret = append(ret, '.')
ret = appendDecimal(ret, ip.v4(1))
ret = append(ret, '.')
ret = appendDecimal(ret, ip.v4(2))
ret = append(ret, '.')
ret = appendDecimal(ret, ip.v4(3))
return ret
}
// string6 formats ip in IPv6 textual representation. It follows the
// guidelines in section 4 of RFC 5952
// (https://tools.ietf.org/html/rfc5952#section-4): no unnecessary
// zeros, use :: to elide the longest run of zeros, and don't use ::
// to compact a single zero field.
func (ip Addr) string6() string {
// Use a zone with a "plausibly long" name, so that most zone-ful
// IP addresses won't require additional allocation.
//
// The compiler does a cool optimization here, where ret ends up
// stack-allocated and so the only allocation this function does
// is to construct the returned string. As such, it's okay to be a
// bit greedy here, size-wise.
const max = len("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff%enp5s0")
ret := make([]byte, 0, max)
ret = ip.appendTo6(ret)
return string(ret)
}
func (ip Addr) appendTo6(ret []byte) []byte {
zeroStart, zeroEnd := uint8(255), uint8(255)
for i := uint8(0); i < 8; i++ {
j := i
for j < 8 && ip.v6u16(j) == 0 {
j++
}
if l := j - i; l >= 2 && l > zeroEnd-zeroStart {
zeroStart, zeroEnd = i, j
}
}
for i := uint8(0); i < 8; i++ {
if i == zeroStart {
ret = append(ret, ':', ':')
i = zeroEnd
if i >= 8 {
break
}
} else if i > 0 {
ret = append(ret, ':')
}
ret = appendHex(ret, ip.v6u16(i))
}
if ip.z != z6noz {
ret = append(ret, '%')
ret = append(ret, ip.Zone()...)
}
return ret
}
// StringExpanded is like String but IPv6 addresses are expanded with leading
// zeroes and no "::" compression. For example, "2001:db8::1" becomes
// "2001:0db8:0000:0000:0000:0000:0000:0001".
func (ip Addr) StringExpanded() string {
switch ip.z {
case z0, z4:
return ip.String()
}
const size = len("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")
ret := make([]byte, 0, size)
for i := uint8(0); i < 8; i++ {
if i > 0 {
ret = append(ret, ':')
}
ret = appendHexPad(ret, ip.v6u16(i))
}
if ip.z != z6noz {
// The addition of a zone will cause a second allocation, but when there
// is no zone the ret slice will be stack allocated.
ret = append(ret, '%')
ret = append(ret, ip.Zone()...)
}
return string(ret)
}
// MarshalText implements the encoding.TextMarshaler interface,
// The encoding is the same as returned by String, with one exception:
// If ip is the zero Addr, the encoding is the empty string.
func (ip Addr) MarshalText() ([]byte, error) {
switch ip.z {
case z0:
return []byte(""), nil
case z4:
max := len("255.255.255.255")
b := make([]byte, 0, max)
return ip.appendTo4(b), nil
default:
max := len("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff%enp5s0")
b := make([]byte, 0, max)
if ip.Is4In6() {
b = append(b, "::ffff:"...)
b = ip.Unmap().appendTo4(b)
if z := ip.Zone(); z != "" {
b = append(b, '%')
b = append(b, z...)
}
return b, nil
}
return ip.appendTo6(b), nil
}
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
// The IP address is expected in a form accepted by ParseAddr.
//
// If text is empty, UnmarshalText sets *ip to the zero Addr and
// returns no error.
func (ip *Addr) UnmarshalText(text []byte) error {
if len(text) == 0 {
*ip = Addr{}
return nil
}
var err error
*ip, err = ParseAddr(string(text))
return err
}
func (ip Addr) marshalBinaryWithTrailingBytes(trailingBytes int) []byte {
var b []byte
switch ip.z {
case z0:
b = make([]byte, trailingBytes)
case z4:
b = make([]byte, 4+trailingBytes)
bePutUint32(b, uint32(ip.addr.lo))
default:
z := ip.Zone()
b = make([]byte, 16+len(z)+trailingBytes)
bePutUint64(b[:8], ip.addr.hi)
bePutUint64(b[8:], ip.addr.lo)
copy(b[16:], z)
}
return b
}
// MarshalBinary implements the encoding.BinaryMarshaler interface.
// It returns a zero-length slice for the zero Addr,
// the 4-byte form for an IPv4 address,
// and the 16-byte form with zone appended for an IPv6 address.
func (ip Addr) MarshalBinary() ([]byte, error) {
return ip.marshalBinaryWithTrailingBytes(0), nil
}
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
// It expects data in the form generated by MarshalBinary.
func (ip *Addr) UnmarshalBinary(b []byte) error {
n := len(b)
switch {
case n == 0:
*ip = Addr{}
return nil
case n == 4:
*ip = AddrFrom4(*(*[4]byte)(b))
return nil
case n == 16:
*ip = ipv6Slice(b)
return nil
case n > 16:
*ip = ipv6Slice(b[:16]).WithZone(string(b[16:]))
return nil
}
return errors.New("unexpected slice size")
}
// AddrPort is an IP and a port number.
type AddrPort struct {
ip Addr
port uint16
}
// AddrPortFrom returns an AddrPort with the provided IP and port.
// It does not allocate.
func AddrPortFrom(ip Addr, port uint16) AddrPort { return AddrPort{ip: ip, port: port} }
// Addr returns p's IP address.
func (p AddrPort) Addr() Addr { return p.ip }
// Port returns p's port.
func (p AddrPort) Port() uint16 { return p.port }
// splitAddrPort splits s into an IP address string and a port
// string. It splits strings shaped like "foo:bar" or "[foo]:bar",
// without further validating the substrings. v6 indicates whether the
// ip string should parse as an IPv6 address or an IPv4 address, in
// order for s to be a valid ip:port string.
func splitAddrPort(s string) (ip, port string, v6 bool, err error) {
i := stringsLastIndexByte(s, ':')
if i == -1 {
return "", "", false, errors.New("not an ip:port")
}
ip, port = s[:i], s[i+1:]
if len(ip) == 0 {
return "", "", false, errors.New("no IP")
}
if len(port) == 0 {
return "", "", false, errors.New("no port")
}
if ip[0] == '[' {
if len(ip) < 2 || ip[len(ip)-1] != ']' {
return "", "", false, errors.New("missing ]")
}
ip = ip[1 : len(ip)-1]
v6 = true
}
return ip, port, v6, nil
}
// ParseAddrPort parses s as an AddrPort.
//
// It doesn't do any name resolution: both the address and the port
// must be numeric.
func ParseAddrPort(s string) (AddrPort, error) {
var ipp AddrPort
ip, port, v6, err := splitAddrPort(s)
if err != nil {
return ipp, err
}
port16, err := strconv.ParseUint(port, 10, 16)
if err != nil {
return ipp, errors.New("invalid port " + strconv.Quote(port) + " parsing " + strconv.Quote(s))
}
ipp.port = uint16(port16)
ipp.ip, err = ParseAddr(ip)
if err != nil {
return AddrPort{}, err
}
if v6 && ipp.ip.Is4() {
return AddrPort{}, errors.New("invalid ip:port " + strconv.Quote(s) + ", square brackets can only be used with IPv6 addresses")
} else if !v6 && ipp.ip.Is6() {
return AddrPort{}, errors.New("invalid ip:port " + strconv.Quote(s) + ", IPv6 addresses must be surrounded by square brackets")
}
return ipp, nil
}
// MustParseAddrPort calls ParseAddrPort(s) and panics on error.
// It is intended for use in tests with hard-coded strings.
func MustParseAddrPort(s string) AddrPort {
ip, err := ParseAddrPort(s)
if err != nil {
panic(err)
}
return ip
}
// isZero reports whether p is the zero AddrPort.
func (p AddrPort) isZero() bool { return p == AddrPort{} }
// IsValid reports whether p.IP() is valid.
// All ports are valid, including zero.
func (p AddrPort) IsValid() bool { return p.ip.IsValid() }
func (p AddrPort) String() string {
switch p.ip.z {
case z0:
return "invalid AddrPort"
case z4:
a := p.ip.As4()
buf := make([]byte, 0, 21)
for i := range a {
buf = strconv.AppendUint(buf, uint64(a[i]), 10)
buf = append(buf, "...:"[i])
}
buf = strconv.AppendUint(buf, uint64(p.port), 10)
return string(buf)
default:
// TODO: this could be more efficient allocation-wise:
return joinHostPort(p.ip.String(), itoa.Itoa(int(p.port)))
}
}
func joinHostPort(host, port string) string {
// We assume that host is a literal IPv6 address if host has
// colons.
if bytealg.IndexByteString(host, ':') >= 0 {
return "[" + host + "]:" + port
}
return host + ":" + port
}
// AppendTo appends a text encoding of p,
// as generated by MarshalText,
// to b and returns the extended buffer.
func (p AddrPort) AppendTo(b []byte) []byte {
switch p.ip.z {
case z0:
return b
case z4:
b = p.ip.appendTo4(b)
default:
if p.ip.Is4In6() {
b = append(b, "[::ffff:"...)
b = p.ip.Unmap().appendTo4(b)
if z := p.ip.Zone(); z != "" {
b = append(b, '%')
b = append(b, z...)
}
} else {
b = append(b, '[')
b = p.ip.appendTo6(b)
}
b = append(b, ']')
}
b = append(b, ':')
b = strconv.AppendInt(b, int64(p.port), 10)
return b
}
// MarshalText implements the encoding.TextMarshaler interface. The
// encoding is the same as returned by String, with one exception: if
// p.Addr() is the zero Addr, the encoding is the empty string.
func (p AddrPort) MarshalText() ([]byte, error) {
var max int
switch p.ip.z {
case z0:
case z4:
max = len("255.255.255.255:65535")
default:
max = len("[ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff%enp5s0]:65535")
}
b := make([]byte, 0, max)
b = p.AppendTo(b)
return b, nil
}
// UnmarshalText implements the encoding.TextUnmarshaler
// interface. The AddrPort is expected in a form
// generated by MarshalText or accepted by ParseAddrPort.
func (p *AddrPort) UnmarshalText(text []byte) error {
if len(text) == 0 {
*p = AddrPort{}
return nil
}
var err error
*p, err = ParseAddrPort(string(text))
return err
}
// MarshalBinary implements the encoding.BinaryMarshaler interface.
// It returns Addr.MarshalBinary with an additional two bytes appended
// containing the port in little-endian.
func (p AddrPort) MarshalBinary() ([]byte, error) {
b := p.Addr().marshalBinaryWithTrailingBytes(2)
lePutUint16(b[len(b)-2:], p.Port())
return b, nil
}
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
// It expects data in the form generated by MarshalBinary.
func (p *AddrPort) UnmarshalBinary(b []byte) error {
if len(b) < 2 {
return errors.New("unexpected slice size")
}
var addr Addr
err := addr.UnmarshalBinary(b[:len(b)-2])
if err != nil {
return err
}
*p = AddrPortFrom(addr, leUint16(b[len(b)-2:]))
return nil
}
// Prefix is an IP address prefix (CIDR) representing an IP network.
//
// The first Bits() of Addr() are specified. The remaining bits match any address.
// The range of Bits() is [0,32] for IPv4 or [0,128] for IPv6.
type Prefix struct {
ip Addr
// bits is logically a uint8 (storing [0,128]) but also
// encodes an "invalid" bit, currently represented by the
// invalidPrefixBits sentinel value. It could be packed into
// the uint8 more with more complicated expressions in the
// accessors, but the extra byte (in padding anyway) doesn't
// hurt and simplifies code below.
bits int16
}
// invalidPrefixBits is the Prefix.bits value used when PrefixFrom is
// outside the range of a uint8. It's returned as the int -1 in the
// public API.
const invalidPrefixBits = -1
// PrefixFrom returns a Prefix with the provided IP address and bit
// prefix length.
//
// It does not allocate. Unlike Addr.Prefix, PrefixFrom does not mask
// off the host bits of ip.
//
// If bits is less than zero or greater than ip.BitLen, Prefix.Bits
// will return an invalid value -1.
func PrefixFrom(ip Addr, bits int) Prefix {
if bits < 0 || bits > ip.BitLen() {
bits = invalidPrefixBits
}
b16 := int16(bits)
return Prefix{
ip: ip.withoutZone(),
bits: b16,
}
}
// Addr returns p's IP address.
func (p Prefix) Addr() Addr { return p.ip }
// Bits returns p's prefix length.
//
// It reports -1 if invalid.
func (p Prefix) Bits() int { return int(p.bits) }
// IsValid reports whether p.Bits() has a valid range for p.IP().
// If p.Addr() is the zero Addr, IsValid returns false.
// Note that if p is the zero Prefix, then p.IsValid() == false.
func (p Prefix) IsValid() bool { return !p.ip.isZero() && p.bits >= 0 && int(p.bits) <= p.ip.BitLen() }
func (p Prefix) isZero() bool { return p == Prefix{} }
// IsSingleIP reports whether p contains exactly one IP.
func (p Prefix) IsSingleIP() bool { return p.bits != 0 && int(p.bits) == p.ip.BitLen() }
// ParsePrefix parses s as an IP address prefix.
// The string can be in the form "192.168.1.0/24" or "2001:db8::/32",
// the CIDR notation defined in RFC 4632 and RFC 4291.
// IPv6 zones are not permitted in prefixes, and an error will be returned if a
// zone is present.
//
// Note that masked address bits are not zeroed. Use Masked for that.
func ParsePrefix(s string) (Prefix, error) {
i := stringsLastIndexByte(s, '/')
if i < 0 {
return Prefix{}, errors.New("netip.ParsePrefix(" + strconv.Quote(s) + "): no '/'")
}
ip, err := ParseAddr(s[:i])
if err != nil {
return Prefix{}, errors.New("netip.ParsePrefix(" + strconv.Quote(s) + "): " + err.Error())
}
// IPv6 zones are not allowed: https://go.dev/issue/51899
if ip.Is6() && ip.z != z6noz {
return Prefix{}, errors.New("netip.ParsePrefix(" + strconv.Quote(s) + "): IPv6 zones cannot be present in a prefix")
}
bitsStr := s[i+1:]
bits, err := strconv.Atoi(bitsStr)
if err != nil {
return Prefix{}, errors.New("netip.ParsePrefix(" + strconv.Quote(s) + ": bad bits after slash: " + strconv.Quote(bitsStr))
}
maxBits := 32
if ip.Is6() {
maxBits = 128
}
if bits < 0 || bits > maxBits {
return Prefix{}, errors.New("netip.ParsePrefix(" + strconv.Quote(s) + ": prefix length out of range")
}
return PrefixFrom(ip, bits), nil
}
// MustParsePrefix calls ParsePrefix(s) and panics on error.
// It is intended for use in tests with hard-coded strings.
func MustParsePrefix(s string) Prefix {
ip, err := ParsePrefix(s)
if err != nil {
panic(err)
}
return ip
}
// Masked returns p in its canonical form, with all but the high
// p.Bits() bits of p.Addr() masked off.
//
// If p is zero or otherwise invalid, Masked returns the zero Prefix.
func (p Prefix) Masked() Prefix {
if m, err := p.ip.Prefix(int(p.bits)); err == nil {
return m
}
return Prefix{}
}
// Contains reports whether the network p includes ip.
//
// An IPv4 address will not match an IPv6 prefix.
// An IPv4-mapped IPv6 address will not match an IPv4 prefix.
// A zero-value IP will not match any prefix.
// If ip has an IPv6 zone, Contains returns false,
// because Prefixes strip zones.
func (p Prefix) Contains(ip Addr) bool {
if !p.IsValid() || ip.hasZone() {
return false
}
if f1, f2 := p.ip.BitLen(), ip.BitLen(); f1 == 0 || f2 == 0 || f1 != f2 {
return false
}
if ip.Is4() {
// xor the IP addresses together; mismatched bits are now ones.
// Shift away the number of bits we don't care about.
// Shifts in Go are more efficient if the compiler can prove
// that the shift amount is smaller than the width of the shifted type (64 here).
// We know that p.bits is in the range 0..32 because p is Valid;
// the compiler doesn't know that, so mask with 63 to help it.
// Now truncate to 32 bits, because this is IPv4.
// If all the bits we care about are equal, the result will be zero.
return uint32((ip.addr.lo^p.ip.addr.lo)>>((32-p.bits)&63)) == 0
} else {
// xor the IP addresses together.
// Mask away the bits we don't care about.
// If all the bits we care about are equal, the result will be zero.
return ip.addr.xor(p.ip.addr).and(mask6(int(p.bits))).isZero()
}
}
// Overlaps reports whether p and o contain any IP addresses in common.
//
// If p and o are of different address families or either have a zero
// IP, it reports false. Like the Contains method, a prefix with an
// IPv4-mapped IPv6 address is still treated as an IPv6 mask.
func (p Prefix) Overlaps(o Prefix) bool {
if !p.IsValid() || !o.IsValid() {
return false
}
if p == o {
return true
}
if p.ip.Is4() != o.ip.Is4() {
return false
}
var minBits int16
if p.bits < o.bits {
minBits = p.bits
} else {
minBits = o.bits
}
if minBits == 0 {
return true
}
// One of these Prefix calls might look redundant, but we don't require
// that p and o values are normalized (via Prefix.Masked) first,
// so the Prefix call on the one that's already minBits serves to zero
// out any remaining bits in IP.
var err error
if p, err = p.ip.Prefix(int(minBits)); err != nil {
return false
}
if o, err = o.ip.Prefix(int(minBits)); err != nil {
return false
}
return p.ip == o.ip
}
// AppendTo appends a text encoding of p,
// as generated by MarshalText,
// to b and returns the extended buffer.
func (p Prefix) AppendTo(b []byte) []byte {
if p.isZero() {
return b
}
if !p.IsValid() {
return append(b, "invalid Prefix"...)
}
// p.ip is non-nil, because p is valid.
if p.ip.z == z4 {
b = p.ip.appendTo4(b)
} else {
if p.ip.Is4In6() {
b = append(b, "::ffff:"...)
b = p.ip.Unmap().appendTo4(b)
} else {
b = p.ip.appendTo6(b)
}
}
b = append(b, '/')
b = appendDecimal(b, uint8(p.bits))
return b
}
// MarshalText implements the encoding.TextMarshaler interface,
// The encoding is the same as returned by String, with one exception:
// If p is the zero value, the encoding is the empty string.
func (p Prefix) MarshalText() ([]byte, error) {
var max int
switch p.ip.z {
case z0:
case z4:
max = len("255.255.255.255/32")
default:
max = len("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff%enp5s0/128")
}
b := make([]byte, 0, max)
b = p.AppendTo(b)
return b, nil
}
// UnmarshalText implements the encoding.TextUnmarshaler interface.
// The IP address is expected in a form accepted by ParsePrefix
// or generated by MarshalText.
func (p *Prefix) UnmarshalText(text []byte) error {
if len(text) == 0 {
*p = Prefix{}
return nil
}
var err error
*p, err = ParsePrefix(string(text))
return err
}
// MarshalBinary implements the encoding.BinaryMarshaler interface.
// It returns Addr.MarshalBinary with an additional byte appended
// containing the prefix bits.
func (p Prefix) MarshalBinary() ([]byte, error) {
b := p.Addr().withoutZone().marshalBinaryWithTrailingBytes(1)
b[len(b)-1] = uint8(p.Bits())
return b, nil
}
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
// It expects data in the form generated by MarshalBinary.
func (p *Prefix) UnmarshalBinary(b []byte) error {
if len(b) < 1 {
return errors.New("unexpected slice size")
}
var addr Addr
err := addr.UnmarshalBinary(b[:len(b)-1])
if err != nil {
return err
}
*p = PrefixFrom(addr, int(b[len(b)-1]))
return nil
}
// String returns the CIDR notation of p: "<ip>/<bits>".
func (p Prefix) String() string {
if !p.IsValid() {
return "invalid Prefix"
}
return p.ip.String() + "/" + itoa.Itoa(int(p.bits))
}