summaryrefslogtreecommitdiffstats
path: root/src/net/ip.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/net/ip.go')
-rw-r--r--src/net/ip.go730
1 files changed, 730 insertions, 0 deletions
diff --git a/src/net/ip.go b/src/net/ip.go
new file mode 100644
index 0000000..c00fe8e
--- /dev/null
+++ b/src/net/ip.go
@@ -0,0 +1,730 @@
+// 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 "internal/bytealg"
+
+// 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 IPMask is a bitmask that can be used to manipulate
+// IP addresses for IP addressing and routing.
+//
+// See type IPNet and func ParseCIDR for details.
+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) // limited 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 reports whether ip is an unspecified address, either
+// the IPv4 address "0.0.0.0" or the IPv6 address "::".
+func (ip IP) IsUnspecified() bool {
+ return ip.Equal(IPv4zero) || ip.Equal(IPv6unspecified)
+}
+
+// IsLoopback reports whether ip is a loopback address.
+func (ip IP) IsLoopback() bool {
+ if ip4 := ip.To4(); ip4 != nil {
+ return ip4[0] == 127
+ }
+ return ip.Equal(IPv6loopback)
+}
+
+// IsMulticast reports whether ip is a multicast address.
+func (ip IP) IsMulticast() bool {
+ if ip4 := ip.To4(); ip4 != nil {
+ return ip4[0]&0xf0 == 0xe0
+ }
+ return len(ip) == IPv6len && ip[0] == 0xff
+}
+
+// IsInterfaceLocalMulticast reports whether ip is
+// an interface-local multicast address.
+func (ip IP) IsInterfaceLocalMulticast() bool {
+ return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x01
+}
+
+// IsLinkLocalMulticast reports whether ip is a link-local
+// multicast address.
+func (ip IP) IsLinkLocalMulticast() bool {
+ if ip4 := ip.To4(); ip4 != nil {
+ return ip4[0] == 224 && ip4[1] == 0 && ip4[2] == 0
+ }
+ return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x02
+}
+
+// IsLinkLocalUnicast reports whether ip is a link-local
+// unicast address.
+func (ip IP) IsLinkLocalUnicast() bool {
+ if ip4 := ip.To4(); ip4 != nil {
+ return ip4[0] == 169 && ip4[1] == 254
+ }
+ return len(ip) == IPv6len && ip[0] == 0xfe && ip[1]&0xc0 == 0x80
+}
+
+// IsGlobalUnicast reports whether ip is a global unicast
+// address.
+//
+// The identification of global unicast addresses uses address type
+// identification as defined in RFC 1122, RFC 4632 and RFC 4291 with
+// the exception of IPv4 directed broadcast addresses.
+// It returns true even if ip is in IPv4 private address space or
+// local IPv6 unicast address space.
+func (ip IP) IsGlobalUnicast() bool {
+ return (len(ip) == IPv4len || len(ip) == IPv6len) &&
+ !ip.Equal(IPv4bcast) &&
+ !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 {
+ 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 && bytealg.Equal(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
+}
+
+// ubtoa encodes the string form of the integer v to dst[start:] and
+// returns the number of bytes written to dst. The caller must ensure
+// that dst has sufficient length.
+func ubtoa(dst []byte, start int, v byte) int {
+ if v < 10 {
+ dst[start] = v + '0'
+ return 1
+ } else if v < 100 {
+ dst[start+1] = v%10 + '0'
+ dst[start] = v/10 + '0'
+ return 2
+ }
+
+ dst[start+2] = v%10 + '0'
+ dst[start+1] = (v/10)%10 + '0'
+ dst[start] = v/100 + '0'
+ return 3
+}
+
+// String returns the string form of the IP address ip.
+// It returns one of 4 forms:
+// - "<nil>", if ip has length 0
+// - dotted decimal ("192.0.2.1"), if ip is an IPv4 or IP4-mapped IPv6 address
+// - IPv6 ("2001:db8::1"), if ip is a valid IPv6 address
+// - the hexadecimal form of ip, without punctuation, if no other cases apply
+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 {
+ const maxIPv4StringLen = len("255.255.255.255")
+ b := make([]byte, maxIPv4StringLen)
+
+ n := ubtoa(b, 0, p4[0])
+ b[n] = '.'
+ n++
+
+ n += ubtoa(b, n, p4[1])
+ b[n] = '.'
+ n++
+
+ n += ubtoa(b, n, p4[2])
+ b[n] = '.'
+ n++
+
+ n += ubtoa(b, n, p4[3])
+ return string(b[:n])
+ }
+ if len(p) != IPv6len {
+ return "?" + hexString(ip)
+ }
+
+ // 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
+ i = j
+ }
+ }
+ // The symbol "::" MUST NOT be used to shorten just one 16 bit 0 field.
+ if e1-e0 <= 2 {
+ e0 = -1
+ e1 = -1
+ }
+
+ const maxLen = len("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")
+ b := make([]byte, 0, maxLen)
+
+ // Print with possible :: in place of run of zeros
+ for i := 0; i < IPv6len; i += 2 {
+ if i == e0 {
+ b = append(b, ':', ':')
+ i = e1
+ if i >= IPv6len {
+ break
+ }
+ } else if i > 0 {
+ b = append(b, ':')
+ }
+ b = appendHex(b, (uint32(p[i])<<8)|uint32(p[i+1]))
+ }
+ return string(b)
+}
+
+func hexString(b []byte) string {
+ s := make([]byte, len(b)*2)
+ for i, tn := range b {
+ s[i*2], s[i*2+1] = hexDigit[tn>>4], hexDigit[tn&0xf]
+ }
+ return string(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, with one exception:
+// When len(ip) is zero, it returns an empty slice.
+func (ip IP) MarshalText() ([]byte, error) {
+ if len(ip) == 0 {
+ return []byte(""), nil
+ }
+ if len(ip) != IPv4len && len(ip) != IPv6len {
+ return nil, &AddrError{Err: "invalid IP address", Addr: hexString(ip)}
+ }
+ 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{Type: "IP address", Text: s}
+ }
+ *ip = x
+ return nil
+}
+
+// Equal reports whether 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 bytealg.Equal(ip, x)
+ }
+ if len(ip) == IPv4len && len(x) == IPv6len {
+ return bytealg.Equal(x[0:12], v4InV6Prefix) && bytealg.Equal(ip, x[12:])
+ }
+ if len(ip) == IPv6len && len(x) == IPv4len {
+ return bytealg.Equal(ip[0:12], v4InV6Prefix) && bytealg.Equal(ip[12:], x)
+ }
+ return false
+}
+
+func (ip IP) matchAddrFamily(x IP) bool {
+ return ip.To4() != nil && x.To4() != nil || ip.To16() != nil && ip.To4() == nil && x.To16() != nil && x.To4() == nil
+}
+
+// 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 {
+ if len(m) == 0 {
+ return "<nil>"
+ }
+ return hexString(m)
+}
+
+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 "192.0.2.0/24"
+// 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 "198.51.100.0/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() + "/" + uitoa(uint(l))
+}
+
+// Parse IPv4 address (d.d.d.d).
+func parseIPv4(s string) IP {
+ var p [IPv4len]byte
+ for i := 0; i < IPv4len; i++ {
+ if len(s) == 0 {
+ // Missing octets.
+ return nil
+ }
+ if i > 0 {
+ if s[0] != '.' {
+ return nil
+ }
+ s = s[1:]
+ }
+ n, c, ok := dtoi(s)
+ if !ok || n > 0xFF {
+ return nil
+ }
+ s = s[c:]
+ p[i] = byte(n)
+ }
+ if len(s) != 0 {
+ return nil
+ }
+ return IPv4(p[0], p[1], p[2], p[3])
+}
+
+// parseIPv6Zone parses s as a literal IPv6 address and its associated zone
+// identifier which is described in RFC 4007.
+func parseIPv6Zone(s string) (IP, string) {
+ s, zone := splitHostZone(s)
+ return parseIPv6(s), zone
+}
+
+// parseIPv6 parses s as a literal IPv6 address described in RFC 4291
+// and RFC 5952.
+func parseIPv6(s string) (ip IP) {
+ ip = make(IP, IPv6len)
+ 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 ip
+ }
+ }
+
+ // Loop, parsing hex numbers followed by colon.
+ i := 0
+ for i < IPv6len {
+ // Hex number.
+ n, c, ok := xtoi(s)
+ if !ok || n > 0xFFFF {
+ return nil
+ }
+
+ // If followed by dot, might be in trailing IPv4.
+ if c < len(s) && s[c] == '.' {
+ if ellipsis < 0 && i != IPv6len-IPv4len {
+ // Not the right place.
+ return nil
+ }
+ if i+IPv4len > IPv6len {
+ // Not enough room.
+ return nil
+ }
+ ip4 := parseIPv4(s)
+ if ip4 == nil {
+ return nil
+ }
+ ip[i] = ip4[12]
+ ip[i+1] = ip4[13]
+ ip[i+2] = ip4[14]
+ ip[i+3] = ip4[15]
+ s = ""
+ i += IPv4len
+ break
+ }
+
+ // Save this 16-bit chunk.
+ ip[i] = byte(n >> 8)
+ ip[i+1] = byte(n)
+ i += 2
+
+ // Stop at end of string.
+ s = s[c:]
+ if len(s) == 0 {
+ break
+ }
+
+ // Otherwise must be followed by colon and more.
+ if s[0] != ':' || len(s) == 1 {
+ return nil
+ }
+ s = s[1:]
+
+ // Look for ellipsis.
+ if s[0] == ':' {
+ if ellipsis >= 0 { // already have one
+ return nil
+ }
+ ellipsis = i
+ s = s[1:]
+ if len(s) == 0 { // can be at end
+ break
+ }
+ }
+ }
+
+ // Must have used entire string.
+ if len(s) != 0 {
+ return nil
+ }
+
+ // If didn't parse enough, expand ellipsis.
+ if i < IPv6len {
+ if ellipsis < 0 {
+ return nil
+ }
+ n := IPv6len - 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 nil
+ }
+ return ip
+}
+
+// ParseIP parses s as an IP address, returning the result.
+// The string s can be in IPv4 dotted decimal ("192.0.2.1"), IPv6
+// ("2001:db8::68"), or IPv4-mapped IPv6 ("::ffff:192.0.2.1") form.
+// If s is not a valid textual representation of an IP address,
+// ParseIP returns nil.
+func ParseIP(s string) IP {
+ for i := 0; i < len(s); i++ {
+ switch s[i] {
+ case '.':
+ return parseIPv4(s)
+ case ':':
+ return parseIPv6(s)
+ }
+ }
+ return nil
+}
+
+// parseIPZone parses s as an IP address, return it and its associated zone
+// identifier (IPv6 only).
+func parseIPZone(s string) (IP, string) {
+ for i := 0; i < len(s); i++ {
+ switch s[i] {
+ case '.':
+ return parseIPv4(s), ""
+ case ':':
+ return parseIPv6Zone(s)
+ }
+ }
+ return nil, ""
+}
+
+// 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) {
+ i := bytealg.IndexByteString(s, '/')
+ if i < 0 {
+ return nil, nil, &ParseError{Type: "CIDR address", Text: s}
+ }
+ addr, mask := s[:i], s[i+1:]
+ iplen := IPv4len
+ ip := parseIPv4(addr)
+ if ip == nil {
+ iplen = IPv6len
+ ip = parseIPv6(addr)
+ }
+ n, i, ok := dtoi(mask)
+ if ip == nil || !ok || i != len(mask) || n < 0 || n > 8*iplen {
+ return nil, nil, &ParseError{Type: "CIDR address", Text: s}
+ }
+ m := CIDRMask(n, 8*iplen)
+ return ip, &IPNet{IP: ip.Mask(m), Mask: m}, nil
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-25 17:19:57 +0000