mirror of https://go.googlesource.com/go
543 lines
14 KiB
Go
543 lines
14 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// IP address manipulations
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//
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// IPv4 addresses are 4 bytes; IPv6 addresses are 16 bytes.
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// An IPv4 address can be converted to an IPv6 address by
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// adding a canonical prefix (10 zeros, 2 0xFFs).
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// This library accepts either size of byte slice but always
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// returns 16-byte addresses.
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package net
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import (
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"internal/bytealg"
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"internal/itoa"
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"internal/stringslite"
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"net/netip"
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)
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// IP address lengths (bytes).
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const (
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IPv4len = 4
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IPv6len = 16
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)
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// An IP is a single IP address, a slice of bytes.
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// Functions in this package accept either 4-byte (IPv4)
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// or 16-byte (IPv6) slices as input.
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//
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// Note that in this documentation, referring to an
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// IP address as an IPv4 address or an IPv6 address
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// is a semantic property of the address, not just the
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// length of the byte slice: a 16-byte slice can still
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// be an IPv4 address.
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type IP []byte
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// An IPMask is a bitmask that can be used to manipulate
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// IP addresses for IP addressing and routing.
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//
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// See type [IPNet] and func [ParseCIDR] for details.
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type IPMask []byte
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// An IPNet represents an IP network.
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type IPNet struct {
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IP IP // network number
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Mask IPMask // network mask
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}
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// IPv4 returns the IP address (in 16-byte form) of the
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// IPv4 address a.b.c.d.
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func IPv4(a, b, c, d byte) IP {
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p := make(IP, IPv6len)
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copy(p, v4InV6Prefix)
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p[12] = a
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p[13] = b
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p[14] = c
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p[15] = d
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return p
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}
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var v4InV6Prefix = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff}
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// IPv4Mask returns the IP mask (in 4-byte form) of the
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// IPv4 mask a.b.c.d.
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func IPv4Mask(a, b, c, d byte) IPMask {
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p := make(IPMask, IPv4len)
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p[0] = a
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p[1] = b
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p[2] = c
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p[3] = d
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return p
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}
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// CIDRMask returns an [IPMask] consisting of 'ones' 1 bits
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// followed by 0s up to a total length of 'bits' bits.
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// For a mask of this form, CIDRMask is the inverse of [IPMask.Size].
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func CIDRMask(ones, bits int) IPMask {
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if bits != 8*IPv4len && bits != 8*IPv6len {
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return nil
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}
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if ones < 0 || ones > bits {
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return nil
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}
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l := bits / 8
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m := make(IPMask, l)
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n := uint(ones)
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for i := 0; i < l; i++ {
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if n >= 8 {
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m[i] = 0xff
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n -= 8
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continue
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}
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m[i] = ^byte(0xff >> n)
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n = 0
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}
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return m
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}
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// Well-known IPv4 addresses
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var (
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IPv4bcast = IPv4(255, 255, 255, 255) // limited broadcast
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IPv4allsys = IPv4(224, 0, 0, 1) // all systems
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IPv4allrouter = IPv4(224, 0, 0, 2) // all routers
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IPv4zero = IPv4(0, 0, 0, 0) // all zeros
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)
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// Well-known IPv6 addresses
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var (
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IPv6zero = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
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IPv6unspecified = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
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IPv6loopback = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
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IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
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IPv6linklocalallnodes = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
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IPv6linklocalallrouters = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}
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)
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// IsUnspecified reports whether ip is an unspecified address, either
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// the IPv4 address "0.0.0.0" or the IPv6 address "::".
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func (ip IP) IsUnspecified() bool {
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return ip.Equal(IPv4zero) || ip.Equal(IPv6unspecified)
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}
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// IsLoopback reports whether ip is a loopback address.
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func (ip IP) IsLoopback() bool {
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if ip4 := ip.To4(); ip4 != nil {
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return ip4[0] == 127
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}
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return ip.Equal(IPv6loopback)
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}
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// IsPrivate reports whether ip is a private address, according to
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// RFC 1918 (IPv4 addresses) and RFC 4193 (IPv6 addresses).
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func (ip IP) IsPrivate() bool {
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if ip4 := ip.To4(); ip4 != nil {
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// Following RFC 1918, Section 3. Private Address Space which says:
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// The Internet Assigned Numbers Authority (IANA) has reserved the
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// following three blocks of the IP address space for private internets:
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// 10.0.0.0 - 10.255.255.255 (10/8 prefix)
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// 172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
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// 192.168.0.0 - 192.168.255.255 (192.168/16 prefix)
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return ip4[0] == 10 ||
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(ip4[0] == 172 && ip4[1]&0xf0 == 16) ||
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(ip4[0] == 192 && ip4[1] == 168)
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}
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// Following RFC 4193, Section 8. IANA Considerations which says:
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// The IANA has assigned the FC00::/7 prefix to "Unique Local Unicast".
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return len(ip) == IPv6len && ip[0]&0xfe == 0xfc
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}
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// IsMulticast reports whether ip is a multicast address.
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func (ip IP) IsMulticast() bool {
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if ip4 := ip.To4(); ip4 != nil {
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return ip4[0]&0xf0 == 0xe0
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}
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return len(ip) == IPv6len && ip[0] == 0xff
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}
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// IsInterfaceLocalMulticast reports whether ip is
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// an interface-local multicast address.
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func (ip IP) IsInterfaceLocalMulticast() bool {
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return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x01
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}
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// IsLinkLocalMulticast reports whether ip is a link-local
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// multicast address.
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func (ip IP) IsLinkLocalMulticast() bool {
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if ip4 := ip.To4(); ip4 != nil {
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return ip4[0] == 224 && ip4[1] == 0 && ip4[2] == 0
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}
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return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x02
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}
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// IsLinkLocalUnicast reports whether ip is a link-local
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// unicast address.
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func (ip IP) IsLinkLocalUnicast() bool {
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if ip4 := ip.To4(); ip4 != nil {
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return ip4[0] == 169 && ip4[1] == 254
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}
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return len(ip) == IPv6len && ip[0] == 0xfe && ip[1]&0xc0 == 0x80
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}
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// IsGlobalUnicast reports whether ip is a global unicast
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// address.
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//
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// The identification of global unicast addresses uses address type
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// identification as defined in RFC 1122, RFC 4632 and RFC 4291 with
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// the exception of IPv4 directed broadcast addresses.
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// It returns true even if ip is in IPv4 private address space or
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// local IPv6 unicast address space.
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func (ip IP) IsGlobalUnicast() bool {
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return (len(ip) == IPv4len || len(ip) == IPv6len) &&
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!ip.Equal(IPv4bcast) &&
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!ip.IsUnspecified() &&
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!ip.IsLoopback() &&
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!ip.IsMulticast() &&
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!ip.IsLinkLocalUnicast()
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}
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// Is p all zeros?
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func isZeros(p IP) bool {
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for i := 0; i < len(p); i++ {
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if p[i] != 0 {
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return false
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}
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}
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return true
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}
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// To4 converts the IPv4 address ip to a 4-byte representation.
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// If ip is not an IPv4 address, To4 returns nil.
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func (ip IP) To4() IP {
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if len(ip) == IPv4len {
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return ip
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}
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if len(ip) == IPv6len &&
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isZeros(ip[0:10]) &&
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ip[10] == 0xff &&
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ip[11] == 0xff {
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return ip[12:16]
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}
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return nil
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}
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// To16 converts the IP address ip to a 16-byte representation.
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// If ip is not an IP address (it is the wrong length), To16 returns nil.
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func (ip IP) To16() IP {
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if len(ip) == IPv4len {
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return IPv4(ip[0], ip[1], ip[2], ip[3])
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}
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if len(ip) == IPv6len {
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return ip
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}
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return nil
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}
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// Default route masks for IPv4.
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var (
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classAMask = IPv4Mask(0xff, 0, 0, 0)
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classBMask = IPv4Mask(0xff, 0xff, 0, 0)
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classCMask = IPv4Mask(0xff, 0xff, 0xff, 0)
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)
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// DefaultMask returns the default IP mask for the IP address ip.
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// Only IPv4 addresses have default masks; DefaultMask returns
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// nil if ip is not a valid IPv4 address.
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func (ip IP) DefaultMask() IPMask {
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if ip = ip.To4(); ip == nil {
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return nil
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}
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switch {
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case ip[0] < 0x80:
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return classAMask
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case ip[0] < 0xC0:
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return classBMask
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default:
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return classCMask
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}
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}
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func allFF(b []byte) bool {
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for _, c := range b {
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if c != 0xff {
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return false
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}
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}
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return true
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}
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// Mask returns the result of masking the IP address ip with mask.
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func (ip IP) Mask(mask IPMask) IP {
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if len(mask) == IPv6len && len(ip) == IPv4len && allFF(mask[:12]) {
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mask = mask[12:]
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}
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if len(mask) == IPv4len && len(ip) == IPv6len && bytealg.Equal(ip[:12], v4InV6Prefix) {
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ip = ip[12:]
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}
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n := len(ip)
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if n != len(mask) {
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return nil
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}
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out := make(IP, n)
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for i := 0; i < n; i++ {
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out[i] = ip[i] & mask[i]
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}
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return out
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}
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// String returns the string form of the IP address ip.
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// It returns one of 4 forms:
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// - "<nil>", if ip has length 0
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// - dotted decimal ("192.0.2.1"), if ip is an IPv4 or IP4-mapped IPv6 address
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// - IPv6 conforming to RFC 5952 ("2001:db8::1"), if ip is a valid IPv6 address
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// - the hexadecimal form of ip, without punctuation, if no other cases apply
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func (ip IP) String() string {
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if len(ip) == 0 {
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return "<nil>"
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}
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if len(ip) != IPv4len && len(ip) != IPv6len {
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return "?" + hexString(ip)
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}
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// If IPv4, use dotted notation.
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if p4 := ip.To4(); len(p4) == IPv4len {
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return netip.AddrFrom4([4]byte(p4)).String()
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}
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return netip.AddrFrom16([16]byte(ip)).String()
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}
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func hexString(b []byte) string {
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s := make([]byte, len(b)*2)
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for i, tn := range b {
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s[i*2], s[i*2+1] = hexDigit[tn>>4], hexDigit[tn&0xf]
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}
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return string(s)
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}
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// ipEmptyString is like ip.String except that it returns
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// an empty string when ip is unset.
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func ipEmptyString(ip IP) string {
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if len(ip) == 0 {
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return ""
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}
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return ip.String()
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}
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// MarshalText implements the [encoding.TextMarshaler] interface.
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// The encoding is the same as returned by [IP.String], with one exception:
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// When len(ip) is zero, it returns an empty slice.
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func (ip IP) MarshalText() ([]byte, error) {
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if len(ip) == 0 {
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return []byte(""), nil
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}
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if len(ip) != IPv4len && len(ip) != IPv6len {
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return nil, &AddrError{Err: "invalid IP address", Addr: hexString(ip)}
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}
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return []byte(ip.String()), nil
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}
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// UnmarshalText implements the [encoding.TextUnmarshaler] interface.
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// The IP address is expected in a form accepted by [ParseIP].
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func (ip *IP) UnmarshalText(text []byte) error {
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if len(text) == 0 {
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*ip = nil
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return nil
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}
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s := string(text)
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x := ParseIP(s)
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if x == nil {
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return &ParseError{Type: "IP address", Text: s}
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}
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*ip = x
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return nil
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}
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// Equal reports whether ip and x are the same IP address.
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// An IPv4 address and that same address in IPv6 form are
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// considered to be equal.
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func (ip IP) Equal(x IP) bool {
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if len(ip) == len(x) {
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return bytealg.Equal(ip, x)
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}
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if len(ip) == IPv4len && len(x) == IPv6len {
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return bytealg.Equal(x[0:12], v4InV6Prefix) && bytealg.Equal(ip, x[12:])
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}
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if len(ip) == IPv6len && len(x) == IPv4len {
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return bytealg.Equal(ip[0:12], v4InV6Prefix) && bytealg.Equal(ip[12:], x)
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}
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return false
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}
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func (ip IP) matchAddrFamily(x IP) bool {
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return ip.To4() != nil && x.To4() != nil || ip.To16() != nil && ip.To4() == nil && x.To16() != nil && x.To4() == nil
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}
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// If mask is a sequence of 1 bits followed by 0 bits,
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// return the number of 1 bits.
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func simpleMaskLength(mask IPMask) int {
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var n int
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for i, v := range mask {
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if v == 0xff {
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n += 8
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continue
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}
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// found non-ff byte
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// count 1 bits
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for v&0x80 != 0 {
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n++
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v <<= 1
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}
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// rest must be 0 bits
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if v != 0 {
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return -1
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}
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for i++; i < len(mask); i++ {
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if mask[i] != 0 {
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return -1
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}
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}
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break
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}
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return n
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}
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// Size returns the number of leading ones and total bits in the mask.
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// If the mask is not in the canonical form--ones followed by zeros--then
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// Size returns 0, 0.
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func (m IPMask) Size() (ones, bits int) {
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ones, bits = simpleMaskLength(m), len(m)*8
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if ones == -1 {
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return 0, 0
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}
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return
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}
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// String returns the hexadecimal form of m, with no punctuation.
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func (m IPMask) String() string {
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if len(m) == 0 {
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return "<nil>"
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}
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return hexString(m)
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}
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func networkNumberAndMask(n *IPNet) (ip IP, m IPMask) {
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if ip = n.IP.To4(); ip == nil {
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ip = n.IP
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if len(ip) != IPv6len {
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return nil, nil
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}
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}
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m = n.Mask
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switch len(m) {
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case IPv4len:
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if len(ip) != IPv4len {
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return nil, nil
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}
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case IPv6len:
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if len(ip) == IPv4len {
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m = m[12:]
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}
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default:
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return nil, nil
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}
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return
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}
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// Contains reports whether the network includes ip.
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func (n *IPNet) Contains(ip IP) bool {
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nn, m := networkNumberAndMask(n)
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if x := ip.To4(); x != nil {
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ip = x
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}
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l := len(ip)
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if l != len(nn) {
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return false
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}
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for i := 0; i < l; i++ {
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if nn[i]&m[i] != ip[i]&m[i] {
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return false
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}
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}
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return true
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}
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// Network returns the address's network name, "ip+net".
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func (n *IPNet) Network() string { return "ip+net" }
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// String returns the CIDR notation of n like "192.0.2.0/24"
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// or "2001:db8::/48" as defined in RFC 4632 and RFC 4291.
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// If the mask is not in the canonical form, it returns the
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// string which consists of an IP address, followed by a slash
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// character and a mask expressed as hexadecimal form with no
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// punctuation like "198.51.100.0/c000ff00".
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func (n *IPNet) String() string {
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if n == nil {
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return "<nil>"
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}
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nn, m := networkNumberAndMask(n)
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if nn == nil || m == nil {
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return "<nil>"
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}
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l := simpleMaskLength(m)
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if l == -1 {
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return nn.String() + "/" + m.String()
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}
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return nn.String() + "/" + itoa.Uitoa(uint(l))
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}
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// ParseIP parses s as an IP address, returning the result.
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// The string s can be in IPv4 dotted decimal ("192.0.2.1"), IPv6
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// ("2001:db8::68"), or IPv4-mapped IPv6 ("::ffff:192.0.2.1") form.
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// If s is not a valid textual representation of an IP address,
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// ParseIP returns nil.
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func ParseIP(s string) IP {
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if addr, valid := parseIP(s); valid {
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return IP(addr[:])
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}
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return nil
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}
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func parseIP(s string) ([16]byte, bool) {
|
|
ip, err := netip.ParseAddr(s)
|
|
if err != nil || ip.Zone() != "" {
|
|
return [16]byte{}, false
|
|
}
|
|
return ip.As16(), true
|
|
}
|
|
|
|
// ParseCIDR parses s as a CIDR notation IP address and prefix length,
|
|
// like "192.0.2.0/24" or "2001:db8::/32", as defined in
|
|
// RFC 4632 and RFC 4291.
|
|
//
|
|
// It returns the IP address and the network implied by the IP and
|
|
// prefix length.
|
|
// For example, ParseCIDR("192.0.2.1/24") returns the IP address
|
|
// 192.0.2.1 and the network 192.0.2.0/24.
|
|
func ParseCIDR(s string) (IP, *IPNet, error) {
|
|
addr, mask, found := stringslite.Cut(s, "/")
|
|
if !found {
|
|
return nil, nil, &ParseError{Type: "CIDR address", Text: s}
|
|
}
|
|
|
|
ipAddr, err := netip.ParseAddr(addr)
|
|
if err != nil || ipAddr.Zone() != "" {
|
|
return nil, nil, &ParseError{Type: "CIDR address", Text: s}
|
|
}
|
|
|
|
n, i, ok := dtoi(mask)
|
|
if !ok || i != len(mask) || n < 0 || n > ipAddr.BitLen() {
|
|
return nil, nil, &ParseError{Type: "CIDR address", Text: s}
|
|
}
|
|
m := CIDRMask(n, ipAddr.BitLen())
|
|
addr16 := ipAddr.As16()
|
|
return IP(addr16[:]), &IPNet{IP: IP(addr16[:]).Mask(m), Mask: m}, nil
|
|
}
|
|
|
|
func copyIP(x IP) IP {
|
|
y := make(IP, len(x))
|
|
copy(y, x)
|
|
return y
|
|
}
|