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-rw-r--r--libgo/go/net/ip.go446
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diff --git a/libgo/go/net/ip.go b/libgo/go/net/ip.go
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+// 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 array but always
+// returns 16-byte addresses.
+
+package net
+
+// IP address lengths (bytes).
+const (
+ IPv4len = 4
+ IPv6len = 16
+)
+
+// An IP is a single IP address, an array of bytes.
+// Functions in this package accept either 4-byte (IP v4)
+// or 16-byte (IP v6) arrays as input. Unless otherwise
+// specified, functions in this package always return
+// IP addresses in 16-byte form using the canonical
+// embedding.
+//
+// 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 array: a 16-byte array can still
+// be an IPv4 address.
+type IP []byte
+
+// An IP mask is an IP address.
+type IPMask []byte
+
+// 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)
+ for i := 0; i < 10; i++ {
+ p[i] = 0
+ }
+ p[10] = 0xff
+ p[11] = 0xff
+ p[12] = a
+ p[13] = b
+ p[14] = c
+ p[15] = d
+ return p
+}
+
+// IPv4Mask returns the IP mask (in 16-byte form) of the
+// IPv4 mask a.b.c.d.
+func IPv4Mask(a, b, c, d byte) IPMask {
+ p := make(IPMask, IPv6len)
+ for i := 0; i < 12; i++ {
+ p[i] = 0xff
+ }
+ p[12] = a
+ p[13] = b
+ p[14] = c
+ p[15] = d
+ return p
+}
+
+// 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 (
+ IPzero = make(IP, IPv6len) // all zeros
+)
+
+// 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
+ }
+ return nil // not reached
+}
+
+// Mask returns the result of masking the IP address ip with mask.
+func (ip IP) Mask(mask IPMask) IP {
+ 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
+}
+
+// Convert i to decimal string.
+func itod(i uint) string {
+ if i == 0 {
+ return "0"
+ }
+
+ // Assemble decimal in reverse order.
+ var b [32]byte
+ bp := len(b)
+ for ; i > 0; i /= 10 {
+ bp--
+ b[bp] = byte(i%10) + '0'
+ }
+
+ return string(b[bp:])
+}
+
+// Convert i to hexadecimal string.
+func itox(i uint) string {
+ if i == 0 {
+ return "0"
+ }
+
+ // Assemble hexadecimal in reverse order.
+ var b [32]byte
+ bp := len(b)
+ for ; i > 0; i /= 16 {
+ bp--
+ b[bp] = "0123456789abcdef"[byte(i%16)]
+ }
+
+ return string(b[bp:])
+}
+
+// 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 ""
+ }
+
+ // If IPv4, use dotted notation.
+ if p4 := p.To4(); len(p4) == 4 {
+ 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 < 16; i += 2 {
+ j := i
+ for j < 16 && 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 < 16; i += 2 {
+ if i == e0 {
+ s += "::"
+ i = e1
+ if i >= 16 {
+ break
+ }
+ } else if i > 0 {
+ s += ":"
+ }
+ s += itox((uint(p[i]) << 8) | uint(p[i+1]))
+ }
+ return s
+}
+
+// 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
+}
+
+// String returns the string representation of mask.
+// If the mask is in the canonical form--ones followed by zeros--the
+// string representation is just the decimal number of ones.
+// If the mask is in a non-canonical form, it is formatted
+// as an IP address.
+func (mask IPMask) String() string {
+ switch len(mask) {
+ case 4:
+ n := simpleMaskLength(mask)
+ if n >= 0 {
+ return itod(uint(n + (IPv6len-IPv4len)*8))
+ }
+ case 16:
+ n := simpleMaskLength(mask)
+ if n >= 12*8 {
+ return itod(uint(n - 12*8))
+ }
+ }
+ return IP(mask).String()
+}
+
+// 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])
+}
+
+// Parse IPv6 address. Many forms.
+// The basic form is a sequence of eight colon-separated
+// 16-bit hex numbers separated by colons,
+// as in 0123:4567:89ab:cdef:0123:4567:89ab:cdef.
+// Two exceptions:
+// * A run of zeros can be replaced with "::".
+// * The last 32 bits can be in IPv4 form.
+// Thus, ::ffff:1.2.3.4 is the IPv4 address 1.2.3.4.
+func parseIPv6(s string) IP {
+ p := make(IP, 16)
+ ellipsis := -1 // position of ellipsis in p
+ i := 0 // index in string 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 p
+ }
+ }
+
+ // Loop, parsing hex numbers followed by colon.
+ j := 0
+L:
+ for j < IPv6len {
+ // Hex number.
+ n, i1, ok := xtoi(s, i)
+ if !ok || n > 0xFFFF {
+ return nil
+ }
+
+ // 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
+ }
+ if j+IPv4len > IPv6len {
+ // Not enough room.
+ return nil
+ }
+ p4 := parseIPv4(s[i:])
+ if p4 == nil {
+ return nil
+ }
+ p[j] = p4[12]
+ p[j+1] = p4[13]
+ p[j+2] = p4[14]
+ p[j+3] = p4[15]
+ i = len(s)
+ j += 4
+ break
+ }
+
+ // Save this 16-bit chunk.
+ p[j] = byte(n >> 8)
+ p[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
+ }
+ i++
+
+ // Look for ellipsis.
+ if s[i] == ':' {
+ if ellipsis >= 0 { // already have one
+ return nil
+ }
+ ellipsis = j
+ if i++; i == len(s) { // can be at end
+ break
+ }
+ }
+ }
+
+ // Must have used entire string.
+ if i != len(s) {
+ return nil
+ }
+
+ // If didn't parse enough, expand ellipsis.
+ if j < IPv6len {
+ if ellipsis < 0 {
+ return nil
+ }
+ n := IPv6len - j
+ for k := j - 1; k >= ellipsis; k-- {
+ p[k+n] = p[k]
+ }
+ for k := ellipsis + n - 1; k >= ellipsis; k-- {
+ p[k] = 0
+ }
+ }
+ return p
+}
+
+// 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 {
+ p := parseIPv4(s)
+ if p != nil {
+ return p
+ }
+ return parseIPv6(s)
+}
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