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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 (IPv4)
// or 16-byte (IPv6) arrays 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 array: a 16-byte array can still
// be an IPv4 address.
type IP []byte
 
// An IP mask is an IP address.
type IPMask []byte
 
// An IPNet represents an IP network.
type IPNet struct {
        IP   IP     // network number
        Mask IPMask // network mask
}
 
// IPv4 returns the IP address (in 16-byte form) of the
// IPv4 address a.b.c.d.
func IPv4(a, b, c, d byte) IP {
        p := make(IP, IPv6len)
        copy(p, v4InV6Prefix)
        p[12] = a
        p[13] = b
        p[14] = c
        p[15] = d
        return p
}
 
var v4InV6Prefix = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff}
 
// IPv4Mask returns the IP mask (in 4-byte form) of the
// IPv4 mask a.b.c.d.
func IPv4Mask(a, b, c, d byte) IPMask {
        p := make(IPMask, IPv4len)
        p[0] = a
        p[1] = b
        p[2] = c
        p[3] = d
        return p
}
 
// CIDRMask returns an IPMask consisting of `ones' 1 bits
// followed by 0s up to a total length of `bits' bits.
// For a mask of this form, CIDRMask is the inverse of IPMask.Size.
func CIDRMask(ones, bits int) IPMask {
        if bits != 8*IPv4len && bits != 8*IPv6len {
                return nil
        }
        if ones < 0 || ones > bits {
                return nil
        }
        l := bits / 8
        m := make(IPMask, l)
        n := uint(ones)
        for i := 0; i < l; i++ {
                if n >= 8 {
                        m[i] = 0xff
                        n -= 8
                        continue
                }
                m[i] = ^byte(0xff >> n)
                n = 0
        }
        return m
}
 
// Well-known IPv4 addresses
var (
        IPv4bcast     = IPv4(255, 255, 255, 255) // broadcast
        IPv4allsys    = IPv4(224, 0, 0, 1)       // all systems
        IPv4allrouter = IPv4(224, 0, 0, 2)       // all routers
        IPv4zero      = IPv4(0, 0, 0, 0)         // all zeros
)
 
// Well-known IPv6 addresses
var (
        IPv6zero                   = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
        IPv6unspecified            = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
        IPv6loopback               = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
        IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
        IPv6linklocalallnodes      = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}
        IPv6linklocalallrouters    = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}
)
 
// IsUnspecified returns true if ip is an unspecified address.
func (ip IP) IsUnspecified() bool {
        if ip.Equal(IPv4zero) || ip.Equal(IPv6unspecified) {
                return true
        }
        return false
}
 
// IsLoopback returns true if ip is a loopback address.
func (ip IP) IsLoopback() bool {
        if ip4 := ip.To4(); ip4 != nil && ip4[0] == 127 {
                return true
        }
        return ip.Equal(IPv6loopback)
}
 
// IsMulticast returns true if ip is a multicast address.
func (ip IP) IsMulticast() bool {
        if ip4 := ip.To4(); ip4 != nil && ip4[0]&0xf0 == 0xe0 {
                return true
        }
        return ip[0] == 0xff
}
 
// IsInterfaceLinkLocalMulticast returns true if ip is
// an interface-local multicast address.
func (ip IP) IsInterfaceLocalMulticast() bool {
        return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x01
}
 
// IsLinkLocalMulticast returns true if ip is a link-local
// multicast address.
func (ip IP) IsLinkLocalMulticast() bool {
        if ip4 := ip.To4(); ip4 != nil && ip4[0] == 224 && ip4[1] == 0 && ip4[2] == 0 {
                return true
        }
        return ip[0] == 0xff && ip[1]&0x0f == 0x02
}
 
// IsLinkLocalUnicast returns true if ip is a link-local
// unicast address.
func (ip IP) IsLinkLocalUnicast() bool {
        if ip4 := ip.To4(); ip4 != nil && ip4[0] == 169 && ip4[1] == 254 {
                return true
        }
        return ip[0] == 0xfe && ip[1]&0xc0 == 0x80
}
 
// IsGlobalUnicast returns true if ip is a global unicast
// address.
func (ip IP) IsGlobalUnicast() bool {
        return !ip.IsUnspecified() &&
                !ip.IsLoopback() &&
                !ip.IsMulticast() &&
                !ip.IsLinkLocalUnicast()
}
 
// Is p all zeros?
func isZeros(p IP) bool {
        for i := 0; i < len(p); i++ {
                if p[i] != 0 {
                        return false
                }
        }
        return true
}
 
// To4 converts the IPv4 address ip to a 4-byte representation.
// If ip is not an IPv4 address, To4 returns nil.
func (ip IP) To4() IP {
        if len(ip) == IPv4len {
                return ip
        }
        if len(ip) == IPv6len &&
                isZeros(ip[0:10]) &&
                ip[10] == 0xff &&
                ip[11] == 0xff {
                return ip[12:16]
        }
        return nil
}
 
// To16 converts the IP address ip to a 16-byte representation.
// If ip is not an IP address (it is the wrong length), To16 returns nil.
func (ip IP) To16() IP {
        if len(ip) == IPv4len {
                return IPv4(ip[0], ip[1], ip[2], ip[3])
        }
        if len(ip) == IPv6len {
                return ip
        }
        return nil
}
 
// Default route masks for IPv4.
var (
        classAMask = IPv4Mask(0xff, 0, 0, 0)
        classBMask = IPv4Mask(0xff, 0xff, 0, 0)
        classCMask = IPv4Mask(0xff, 0xff, 0xff, 0)
)
 
// DefaultMask returns the default IP mask for the IP address ip.
// Only IPv4 addresses have default masks; DefaultMask returns
// nil if ip is not a valid IPv4 address.
func (ip IP) DefaultMask() IPMask {
        if ip = ip.To4(); ip == nil {
                return nil
        }
        switch true {
        case ip[0] < 0x80:
                return classAMask
        case ip[0] < 0xC0:
                return classBMask
        default:
                return classCMask
        }
        return nil // not reached
}
 
func allFF(b []byte) bool {
        for _, c := range b {
                if c != 0xff {
                        return false
                }
        }
        return true
}
 
// Mask returns the result of masking the IP address ip with mask.
func (ip IP) Mask(mask IPMask) IP {
        if len(mask) == IPv6len && len(ip) == IPv4len && allFF(mask[:12]) {
                mask = mask[12:]
        }
        if len(mask) == IPv4len && len(ip) == IPv6len && bytesEqual(ip[:12], v4InV6Prefix) {
                ip = ip[12:]
        }
        n := len(ip)
        if n != len(mask) {
                return nil
        }
        out := make(IP, n)
        for i := 0; i < n; i++ {
                out[i] = ip[i] & mask[i]
        }
        return out
}
 
// String returns the string form of the IP address ip.
// If the address is an IPv4 address, the string representation
// is dotted decimal ("74.125.19.99").  Otherwise the representation
// is IPv6 ("2001:4860:0:2001::68").
func (ip IP) String() string {
        p := ip
 
        if len(ip) == 0 {
                return ""
        }
 
        // If IPv4, use dotted notation.
        if p4 := p.To4(); len(p4) == IPv4len {
                return itod(uint(p4[0])) + "." +
                        itod(uint(p4[1])) + "." +
                        itod(uint(p4[2])) + "." +
                        itod(uint(p4[3]))
        }
        if len(p) != IPv6len {
                return "?"
        }
 
        // Find longest run of zeros.
        e0 := -1
        e1 := -1
        for i := 0; i < IPv6len; i += 2 {
                j := i
                for j < IPv6len && p[j] == 0 && p[j+1] == 0 {
                        j += 2
                }
                if j > i && j-i > e1-e0 {
                        e0 = i
                        e1 = j
                }
        }
        // The symbol "::" MUST NOT be used to shorten just one 16 bit 0 field.
        if e1-e0 <= 2 {
                e0 = -1
                e1 = -1
        }
 
        // Print with possible :: in place of run of zeros
        var s string
        for i := 0; i < IPv6len; i += 2 {
                if i == e0 {
                        s += "::"
                        i = e1
                        if i >= IPv6len {
                                break
                        }
                } else if i > 0 {
                        s += ":"
                }
                s += itox((uint(p[i])<<8)|uint(p[i+1]), 1)
        }
        return s
}
 
// Equal returns true if ip and x are the same IP address.
// An IPv4 address and that same address in IPv6 form are
// considered to be equal.
func (ip IP) Equal(x IP) bool {
        if len(ip) == len(x) {
                return bytesEqual(ip, x)
        }
        if len(ip) == IPv4len && len(x) == IPv6len {
                return bytesEqual(x[0:12], v4InV6Prefix) && bytesEqual(ip, x[12:])
        }
        if len(ip) == IPv6len && len(x) == IPv4len {
                return bytesEqual(ip[0:12], v4InV6Prefix) && bytesEqual(ip[12:], x)
        }
        return false
}
 
func bytesEqual(x, y []byte) bool {
        if len(x) != len(y) {
                return false
        }
        for i, b := range x {
                if y[i] != b {
                        return false
                }
        }
        return true
}
 
// If mask is a sequence of 1 bits followed by 0 bits,
// return the number of 1 bits.
func simpleMaskLength(mask IPMask) int {
        var n int
        for i, v := range mask {
                if v == 0xff {
                        n += 8
                        continue
                }
                // found non-ff byte
                // count 1 bits
                for v&0x80 != 0 {
                        n++
                        v <<= 1
                }
                // rest must be 0 bits
                if v != 0 {
                        return -1
                }
                for i++; i < len(mask); i++ {
                        if mask[i] != 0 {
                                return -1
                        }
                }
                break
        }
        return n
}
 
// Size returns the number of leading ones and total bits in the mask.
// If the mask is not in the canonical form--ones followed by zeros--then
// Size returns 0, 0.
func (m IPMask) Size() (ones, bits int) {
        ones, bits = simpleMaskLength(m), len(m)*8
        if ones == -1 {
                return 0, 0
        }
        return
}
 
// String returns the hexadecimal form of m, with no punctuation.
func (m IPMask) String() string {
        s := ""
        for _, b := range m {
                s += itox(uint(b), 2)
        }
        if len(s) == 0 {
                return ""
        }
        return s
}
 
func networkNumberAndMask(n *IPNet) (ip IP, m IPMask) {
        if ip = n.IP.To4(); ip == nil {
                ip = n.IP
                if len(ip) != IPv6len {
                        return nil, nil
                }
        }
        m = n.Mask
        switch len(m) {
        case IPv4len:
                if len(ip) != IPv4len {
                        return nil, nil
                }
        case IPv6len:
                if len(ip) == IPv4len {
                        m = m[12:]
                }
        default:
                return nil, nil
        }
        return
}
 
// Contains reports whether the network includes ip.
func (n *IPNet) Contains(ip IP) bool {
        nn, m := networkNumberAndMask(n)
        if x := ip.To4(); x != nil {
                ip = x
        }
        l := len(ip)
        if l != len(nn) {
                return false
        }
        for i := 0; i < l; i++ {
                if nn[i]&m[i] != ip[i]&m[i] {
                        return false
                }
        }
        return true
}
 
// String returns the CIDR notation of n like "192.168.100.1/24"
// or "2001:DB8::/48" as defined in RFC 4632 and RFC 4291.
// If the mask is not in the canonical form, it returns the
// string which consists of an IP address, followed by a slash
// character and a mask expressed as hexadecimal form with no
// punctuation like "192.168.100.1/c000ff00".
func (n *IPNet) String() string {
        nn, m := networkNumberAndMask(n)
        if nn == nil || m == nil {
                return ""
        }
        l := simpleMaskLength(m)
        if l == -1 {
                return nn.String() + "/" + m.String()
        }
        return nn.String() + "/" + itod(uint(l))
}
 
// Network returns the address's network name, "ip+net".
func (n *IPNet) Network() string { return "ip+net" }
 
// 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, IPv6len)
        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
        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 += IPv4len
                        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
}
 
// A ParseError represents a malformed text string and the type of string that was expected.
type ParseError struct {
        Type string
        Text string
}
 
func (e *ParseError) Error() string {
        return "invalid " + e.Type + ": " + e.Text
}
 
func parseIP(s string) IP {
        if p := parseIPv4(s); p != nil {
                return p
        }
        if p := parseIPv6(s); p != nil {
                return p
        }
        return nil
}
 
// ParseIP parses s as an IP address, returning the result.
// The string s can be in dotted decimal ("74.125.19.99")
// or IPv6 ("2001:4860:0:2001::68") form.
// If s is not a valid textual representation of an IP address,
// ParseIP returns nil.
func ParseIP(s string) IP {
        if p := parseIPv4(s); p != nil {
                return p
        }
        return parseIPv6(s)
}
 
// ParseCIDR parses s as a CIDR notation IP address and mask,
// like "192.168.100.1/24" or "2001:DB8::/48", as defined in
// RFC 4632 and RFC 4291.
//
// It returns the IP address and the network implied by the IP
// and mask.  For example, ParseCIDR("192.168.100.1/16") returns
// the IP address 192.168.100.1 and the network 192.168.0.0/16.
func ParseCIDR(s string) (IP, *IPNet, error) {
        i := byteIndex(s, '/')
        if i < 0 {
                return nil, nil, &ParseError{"CIDR address", s}
        }
        ipstr, maskstr := s[:i], s[i+1:]
        iplen := IPv4len
        ip := parseIPv4(ipstr)
        if ip == nil {
                iplen = IPv6len
                ip = parseIPv6(ipstr)
        }
        n, i, ok := dtoi(maskstr, 0)
        if ip == nil || !ok || i != len(maskstr) || n < 0 || n > 8*iplen {
                return nil, nil, &ParseError{"CIDR address", s}
        }
        m := CIDRMask(n, 8*iplen)
        return ip, &IPNet{ip.Mask(m), m}, nil
}

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Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [net/] [ip.go] - Blame information for rev 747

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2009 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`// IP address manipulations`
6			`//`
7			`// IPv4 addresses are 4 bytes; IPv6 addresses are 16 bytes.`
8			`// An IPv4 address can be converted to an IPv6 address by`
9			`// adding a canonical prefix (10 zeros, 2 0xFFs).`
10			`// This library accepts either size of byte array but always`
11			`// returns 16-byte addresses.`
12
13			`package net`
14
15			`// IP address lengths (bytes).`
16			`const (`
17			`IPv4len = 4`
18			`IPv6len = 16`
19			`)`
20
21			`// An IP is a single IP address, an array of bytes.`
22			`// Functions in this package accept either 4-byte (IPv4)`
23			`// or 16-byte (IPv6) arrays as input.`
24			`//`
25			`// Note that in this documentation, referring to an`
26			`// IP address as an IPv4 address or an IPv6 address`
27			`// is a semantic property of the address, not just the`
28			`// length of the byte array: a 16-byte array can still`
29			`// be an IPv4 address.`
30			`type IP []byte`
31
32			`// An IP mask is an IP address.`
33			`type IPMask []byte`
34
35			`// An IPNet represents an IP network.`
36			`type IPNet struct {`
37			`IP IP // network number`
38			`Mask IPMask // network mask`
39			`}`
40
41			`// IPv4 returns the IP address (in 16-byte form) of the`
42			`// IPv4 address a.b.c.d.`
43			`func IPv4(a, b, c, d byte) IP {`
44			`p := make(IP, IPv6len)`
45			`copy(p, v4InV6Prefix)`
46			`p[12] = a`
47			`p[13] = b`
48			`p[14] = c`
49			`p[15] = d`
50			`return p`
51			`}`
52
53			`var v4InV6Prefix = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff}`
54
55			`// IPv4Mask returns the IP mask (in 4-byte form) of the`
56			`// IPv4 mask a.b.c.d.`
57			`func IPv4Mask(a, b, c, d byte) IPMask {`
58			`p := make(IPMask, IPv4len)`
59			`p[0] = a`
60			`p[1] = b`
61			`p[2] = c`
62			`p[3] = d`
63			`return p`
64			`}`
65
66			// CIDRMask returns an IPMask consisting of `ones' 1 bits
67			// followed by 0s up to a total length of `bits' bits.
68			`// For a mask of this form, CIDRMask is the inverse of IPMask.Size.`
69			`func CIDRMask(ones, bits int) IPMask {`
70			`if bits != 8IPv4len && bits != 8IPv6len {`
71			`return nil`
72			`}`
73			`if ones < 0 \|\| ones > bits {`
74			`return nil`
75			`}`
76			`l := bits / 8`
77			`m := make(IPMask, l)`
78			`n := uint(ones)`
79			`for i := 0; i < l; i++ {`
80			`if n >= 8 {`
81			`m[i] = 0xff`
82			`n -= 8`
83			`continue`
84			`}`
85			`m[i] = ^byte(0xff >> n)`
86			`n = 0`
87			`}`
88			`return m`
89			`}`
90
91			`// Well-known IPv4 addresses`
92			`var (`
93			`IPv4bcast = IPv4(255, 255, 255, 255) // broadcast`
94			`IPv4allsys = IPv4(224, 0, 0, 1) // all systems`
95			`IPv4allrouter = IPv4(224, 0, 0, 2) // all routers`
96			`IPv4zero = IPv4(0, 0, 0, 0) // all zeros`
97			`)`
98
99			`// Well-known IPv6 addresses`
100			`var (`
101			`IPv6zero = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}`
102			`IPv6unspecified = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}`
103			`IPv6loopback = IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}`
104			`IPv6interfacelocalallnodes = IP{0xff, 0x01, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}`
105			`IPv6linklocalallnodes = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01}`
106			`IPv6linklocalallrouters = IP{0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x02}`
107			`)`
108
109			`// IsUnspecified returns true if ip is an unspecified address.`
110			`func (ip IP) IsUnspecified() bool {`
111			`if ip.Equal(IPv4zero) \|\| ip.Equal(IPv6unspecified) {`
112			`return true`
113			`}`
114			`return false`
115			`}`
116
117			`// IsLoopback returns true if ip is a loopback address.`
118			`func (ip IP) IsLoopback() bool {`
119			`if ip4 := ip.To4(); ip4 != nil && ip4[0] == 127 {`
120			`return true`
121			`}`
122			`return ip.Equal(IPv6loopback)`
123			`}`
124
125			`// IsMulticast returns true if ip is a multicast address.`
126			`func (ip IP) IsMulticast() bool {`
127			`if ip4 := ip.To4(); ip4 != nil && ip4[0]&0xf0 == 0xe0 {`
128			`return true`
129			`}`
130			`return ip[0] == 0xff`
131			`}`
132
133			`// IsInterfaceLinkLocalMulticast returns true if ip is`
134			`// an interface-local multicast address.`
135			`func (ip IP) IsInterfaceLocalMulticast() bool {`
136			`return len(ip) == IPv6len && ip[0] == 0xff && ip[1]&0x0f == 0x01`
137			`}`
138
139			`// IsLinkLocalMulticast returns true if ip is a link-local`
140			`// multicast address.`
141			`func (ip IP) IsLinkLocalMulticast() bool {`
142			`if ip4 := ip.To4(); ip4 != nil && ip4[0] == 224 && ip4[1] == 0 && ip4[2] == 0 {`
143			`return true`
144			`}`
145			`return ip[0] == 0xff && ip[1]&0x0f == 0x02`
146			`}`
147
148			`// IsLinkLocalUnicast returns true if ip is a link-local`
149			`// unicast address.`
150			`func (ip IP) IsLinkLocalUnicast() bool {`
151			`if ip4 := ip.To4(); ip4 != nil && ip4[0] == 169 && ip4[1] == 254 {`
152			`return true`
153			`}`
154			`return ip[0] == 0xfe && ip[1]&0xc0 == 0x80`
155			`}`
156
157			`// IsGlobalUnicast returns true if ip is a global unicast`
158			`// address.`
159			`func (ip IP) IsGlobalUnicast() bool {`
160			`return !ip.IsUnspecified() &&`
161			`!ip.IsLoopback() &&`
162			`!ip.IsMulticast() &&`
163			`!ip.IsLinkLocalUnicast()`
164			`}`
165
166			`// Is p all zeros?`
167			`func isZeros(p IP) bool {`
168			`for i := 0; i < len(p); i++ {`
169			`if p[i] != 0 {`
170			`return false`
171			`}`
172			`}`
173			`return true`
174			`}`
175
176			`// To4 converts the IPv4 address ip to a 4-byte representation.`
177			`// If ip is not an IPv4 address, To4 returns nil.`
178			`func (ip IP) To4() IP {`
179			`if len(ip) == IPv4len {`
180			`return ip`
181			`}`
182			`if len(ip) == IPv6len &&`
183			`isZeros(ip[0:10]) &&`
184			`ip[10] == 0xff &&`
185			`ip[11] == 0xff {`
186			`return ip[12:16]`
187			`}`
188			`return nil`
189			`}`
190
191			`// To16 converts the IP address ip to a 16-byte representation.`
192			`// If ip is not an IP address (it is the wrong length), To16 returns nil.`
193			`func (ip IP) To16() IP {`
194			`if len(ip) == IPv4len {`
195			`return IPv4(ip[0], ip[1], ip[2], ip[3])`
196			`}`
197			`if len(ip) == IPv6len {`
198			`return ip`
199			`}`
200			`return nil`
201			`}`
202
203			`// Default route masks for IPv4.`
204			`var (`
205			`classAMask = IPv4Mask(0xff, 0, 0, 0)`
206			`classBMask = IPv4Mask(0xff, 0xff, 0, 0)`
207			`classCMask = IPv4Mask(0xff, 0xff, 0xff, 0)`
208			`)`
209
210			`// DefaultMask returns the default IP mask for the IP address ip.`
211			`// Only IPv4 addresses have default masks; DefaultMask returns`
212			`// nil if ip is not a valid IPv4 address.`
213			`func (ip IP) DefaultMask() IPMask {`
214			`if ip = ip.To4(); ip == nil {`
215			`return nil`
216			`}`
217			`switch true {`
218			`case ip[0] < 0x80:`
219			`return classAMask`
220			`case ip[0] < 0xC0:`
221			`return classBMask`
222			`default:`
223			`return classCMask`
224			`}`
225			`return nil // not reached`
226			`}`
227
228			`func allFF(b []byte) bool {`
229			`for _, c := range b {`
230			`if c != 0xff {`
231			`return false`
232			`}`
233			`}`
234			`return true`
235			`}`
236
237			`// Mask returns the result of masking the IP address ip with mask.`
238			`func (ip IP) Mask(mask IPMask) IP {`
239			`if len(mask) == IPv6len && len(ip) == IPv4len && allFF(mask[:12]) {`
240			`mask = mask[12:]`
241			`}`
242			`if len(mask) == IPv4len && len(ip) == IPv6len && bytesEqual(ip[:12], v4InV6Prefix) {`
243			`ip = ip[12:]`
244			`}`
245			`n := len(ip)`
246			`if n != len(mask) {`
247			`return nil`
248			`}`
249			`out := make(IP, n)`
250			`for i := 0; i < n; i++ {`
251			`out[i] = ip[i] & mask[i]`
252			`}`
253			`return out`
254			`}`
255
256			`// String returns the string form of the IP address ip.`
257			`// If the address is an IPv4 address, the string representation`
258			`// is dotted decimal ("74.125.19.99"). Otherwise the representation`
259			`// is IPv6 ("2001:4860:0:2001::68").`
260			`func (ip IP) String() string {`
261			`p := ip`
262
263			`if len(ip) == 0 {`
264			`return ""`
265			`}`
266
267			`// If IPv4, use dotted notation.`
268			`if p4 := p.To4(); len(p4) == IPv4len {`
269			`return itod(uint(p4[0])) + "." +`
270			`itod(uint(p4[1])) + "." +`
271			`itod(uint(p4[2])) + "." +`
272			`itod(uint(p4[3]))`
273			`}`
274			`if len(p) != IPv6len {`
275			`return "?"`
276			`}`
277
278			`// Find longest run of zeros.`
279			`e0 := -1`
280			`e1 := -1`
281			`for i := 0; i < IPv6len; i += 2 {`
282			`j := i`
283			`for j < IPv6len && p[j] == 0 && p[j+1] == 0 {`
284			`j += 2`
285			`}`
286			`if j > i && j-i > e1-e0 {`
287			`e0 = i`
288			`e1 = j`
289			`}`
290			`}`
291			`// The symbol "::" MUST NOT be used to shorten just one 16 bit 0 field.`
292			`if e1-e0 <= 2 {`
293			`e0 = -1`
294			`e1 = -1`
295			`}`
296
297			`// Print with possible :: in place of run of zeros`
298			`var s string`
299			`for i := 0; i < IPv6len; i += 2 {`
300			`if i == e0 {`
301			`s += "::"`
302			`i = e1`
303			`if i >= IPv6len {`
304			`break`
305			`}`
306			`} else if i > 0 {`
307			`s += ":"`
308			`}`
309			`s += itox((uint(p[i])<<8)\|uint(p[i+1]), 1)`
310			`}`
311			`return s`
312			`}`
313
314			`// Equal returns true if ip and x are the same IP address.`
315			`// An IPv4 address and that same address in IPv6 form are`
316			`// considered to be equal.`
317			`func (ip IP) Equal(x IP) bool {`
318			`if len(ip) == len(x) {`
319			`return bytesEqual(ip, x)`
320			`}`
321			`if len(ip) == IPv4len && len(x) == IPv6len {`
322			`return bytesEqual(x[0:12], v4InV6Prefix) && bytesEqual(ip, x[12:])`
323			`}`
324			`if len(ip) == IPv6len && len(x) == IPv4len {`
325			`return bytesEqual(ip[0:12], v4InV6Prefix) && bytesEqual(ip[12:], x)`
326			`}`
327			`return false`
328			`}`
329
330			`func bytesEqual(x, y []byte) bool {`
331			`if len(x) != len(y) {`
332			`return false`
333			`}`
334			`for i, b := range x {`
335			`if y[i] != b {`
336			`return false`
337			`}`
338			`}`
339			`return true`
340			`}`
341
342			`// If mask is a sequence of 1 bits followed by 0 bits,`
343			`// return the number of 1 bits.`
344			`func simpleMaskLength(mask IPMask) int {`
345			`var n int`
346			`for i, v := range mask {`
347			`if v == 0xff {`
348			`n += 8`
349			`continue`
350			`}`
351			`// found non-ff byte`
352			`// count 1 bits`
353			`for v&0x80 != 0 {`
354			`n++`
355			`v <<= 1`
356			`}`
357			`// rest must be 0 bits`
358			`if v != 0 {`
359			`return -1`
360			`}`
361			`for i++; i < len(mask); i++ {`
362			`if mask[i] != 0 {`
363			`return -1`
364			`}`
365			`}`
366			`break`
367			`}`
368			`return n`
369			`}`
370
371			`// Size returns the number of leading ones and total bits in the mask.`
372			`// If the mask is not in the canonical form--ones followed by zeros--then`
373			`// Size returns 0, 0.`
374			`func (m IPMask) Size() (ones, bits int) {`
375			`ones, bits = simpleMaskLength(m), len(m)*8`
376			`if ones == -1 {`
377			`return 0, 0`
378			`}`
379			`return`
380			`}`
381
382			`// String returns the hexadecimal form of m, with no punctuation.`
383			`func (m IPMask) String() string {`
384			`s := ""`
385			`for _, b := range m {`
386			`s += itox(uint(b), 2)`
387			`}`
388			`if len(s) == 0 {`
389			`return ""`
390			`}`
391			`return s`
392			`}`
393
394			`func networkNumberAndMask(n *IPNet) (ip IP, m IPMask) {`
395			`if ip = n.IP.To4(); ip == nil {`
396			`ip = n.IP`
397			`if len(ip) != IPv6len {`
398			`return nil, nil`
399			`}`
400			`}`
401			`m = n.Mask`
402			`switch len(m) {`
403			`case IPv4len:`
404			`if len(ip) != IPv4len {`
405			`return nil, nil`
406			`}`
407			`case IPv6len:`
408			`if len(ip) == IPv4len {`
409			`m = m[12:]`
410			`}`
411			`default:`
412			`return nil, nil`
413			`}`
414			`return`
415			`}`
416
417			`// Contains reports whether the network includes ip.`
418			`func (n *IPNet) Contains(ip IP) bool {`
419			`nn, m := networkNumberAndMask(n)`
420			`if x := ip.To4(); x != nil {`
421			`ip = x`
422			`}`
423			`l := len(ip)`
424			`if l != len(nn) {`
425			`return false`
426			`}`
427			`for i := 0; i < l; i++ {`
428			`if nn[i]&m[i] != ip[i]&m[i] {`
429			`return false`
430			`}`
431			`}`
432			`return true`
433			`}`
434
435			`// String returns the CIDR notation of n like "192.168.100.1/24"`
436			`// or "2001:DB8::/48" as defined in RFC 4632 and RFC 4291.`
437			`// If the mask is not in the canonical form, it returns the`
438			`// string which consists of an IP address, followed by a slash`
439			`// character and a mask expressed as hexadecimal form with no`
440			`// punctuation like "192.168.100.1/c000ff00".`
441			`func (n *IPNet) String() string {`
442			`nn, m := networkNumberAndMask(n)`
443			`if nn == nil \|\| m == nil {`
444			`return ""`
445			`}`
446			`l := simpleMaskLength(m)`
447			`if l == -1 {`
448			`return nn.String() + "/" + m.String()`
449			`}`
450			`return nn.String() + "/" + itod(uint(l))`
451			`}`
452
453			`// Network returns the address's network name, "ip+net".`
454			`func (n *IPNet) Network() string { return "ip+net" }`
455
456			`// Parse IPv4 address (d.d.d.d).`
457			`func parseIPv4(s string) IP {`
458			`var p [IPv4len]byte`
459			`i := 0`
460			`for j := 0; j < IPv4len; j++ {`
461			`if i >= len(s) {`
462			`// Missing octets.`
463			`return nil`
464			`}`
465			`if j > 0 {`
466			`if s[i] != '.' {`
467			`return nil`
468			`}`
469			`i++`
470			`}`
471			`var (`
472			`n int`
473			`ok bool`
474			`)`
475			`n, i, ok = dtoi(s, i)`
476			`if !ok \|\| n > 0xFF {`
477			`return nil`
478			`}`
479			`p[j] = byte(n)`
480			`}`
481			`if i != len(s) {`
482			`return nil`
483			`}`
484			`return IPv4(p[0], p[1], p[2], p[3])`
485			`}`
486
487			`// Parse IPv6 address. Many forms.`
488			`// The basic form is a sequence of eight colon-separated`
489			`// 16-bit hex numbers separated by colons,`
490			`// as in 0123:4567:89ab:cdef:0123:4567:89ab:cdef.`
491			`// Two exceptions:`
492			`// * A run of zeros can be replaced with "::".`
493			`// * The last 32 bits can be in IPv4 form.`
494			`// Thus, ::ffff:1.2.3.4 is the IPv4 address 1.2.3.4.`
495			`func parseIPv6(s string) IP {`
496			`p := make(IP, IPv6len)`
497			`ellipsis := -1 // position of ellipsis in p`
498			`i := 0 // index in string s`
499
500			`// Might have leading ellipsis`
501			`if len(s) >= 2 && s[0] == ':' && s[1] == ':' {`
502			`ellipsis = 0`
503			`i = 2`
504			`// Might be only ellipsis`
505			`if i == len(s) {`
506			`return p`
507			`}`
508			`}`
509
510			`// Loop, parsing hex numbers followed by colon.`
511			`j := 0`
512			`for j < IPv6len {`
513			`// Hex number.`
514			`n, i1, ok := xtoi(s, i)`
515			`if !ok \|\| n > 0xFFFF {`
516			`return nil`
517			`}`
518
519			`// If followed by dot, might be in trailing IPv4.`
520			`if i1 < len(s) && s[i1] == '.' {`
521			`if ellipsis < 0 && j != IPv6len-IPv4len {`
522			`// Not the right place.`
523			`return nil`
524			`}`
525			`if j+IPv4len > IPv6len {`
526			`// Not enough room.`
527			`return nil`
528			`}`
529			`p4 := parseIPv4(s[i:])`
530			`if p4 == nil {`
531			`return nil`
532			`}`
533			`p[j] = p4[12]`
534			`p[j+1] = p4[13]`
535			`p[j+2] = p4[14]`
536			`p[j+3] = p4[15]`
537			`i = len(s)`
538			`j += IPv4len`
539			`break`
540			`}`
541
542			`// Save this 16-bit chunk.`
543			`p[j] = byte(n >> 8)`
544			`p[j+1] = byte(n)`
545			`j += 2`
546
547			`// Stop at end of string.`
548			`i = i1`
549			`if i == len(s) {`
550			`break`
551			`}`
552
553			`// Otherwise must be followed by colon and more.`
554			`if s[i] != ':' \|\| i+1 == len(s) {`
555			`return nil`
556			`}`
557			`i++`
558
559			`// Look for ellipsis.`
560			`if s[i] == ':' {`
561			`if ellipsis >= 0 { // already have one`
562			`return nil`
563			`}`
564			`ellipsis = j`
565			`if i++; i == len(s) { // can be at end`
566			`break`
567			`}`
568			`}`
569			`}`
570
571			`// Must have used entire string.`
572			`if i != len(s) {`
573			`return nil`
574			`}`
575
576			`// If didn't parse enough, expand ellipsis.`
577			`if j < IPv6len {`
578			`if ellipsis < 0 {`
579			`return nil`
580			`}`
581			`n := IPv6len - j`
582			`for k := j - 1; k >= ellipsis; k-- {`
583			`p[k+n] = p[k]`
584			`}`
585			`for k := ellipsis + n - 1; k >= ellipsis; k-- {`
586			`p[k] = 0`
587			`}`
588			`}`
589			`return p`
590			`}`
591
592			`// A ParseError represents a malformed text string and the type of string that was expected.`
593			`type ParseError struct {`
594			`Type string`
595			`Text string`
596			`}`
597
598			`func (e *ParseError) Error() string {`
599			`return "invalid " + e.Type + ": " + e.Text`
600			`}`
601
602			`func parseIP(s string) IP {`
603			`if p := parseIPv4(s); p != nil {`
604			`return p`
605			`}`
606			`if p := parseIPv6(s); p != nil {`
607			`return p`
608			`}`
609			`return nil`
610			`}`
611
612			`// ParseIP parses s as an IP address, returning the result.`
613			`// The string s can be in dotted decimal ("74.125.19.99")`
614			`// or IPv6 ("2001:4860:0:2001::68") form.`
615			`// If s is not a valid textual representation of an IP address,`
616			`// ParseIP returns nil.`
617			`func ParseIP(s string) IP {`
618			`if p := parseIPv4(s); p != nil {`
619			`return p`
620			`}`
621			`return parseIPv6(s)`
622			`}`
623
624			`// ParseCIDR parses s as a CIDR notation IP address and mask,`
625			`// like "192.168.100.1/24" or "2001:DB8::/48", as defined in`
626			`// RFC 4632 and RFC 4291.`
627			`//`
628			`// It returns the IP address and the network implied by the IP`
629			`// and mask. For example, ParseCIDR("192.168.100.1/16") returns`
630			`// the IP address 192.168.100.1 and the network 192.168.0.0/16.`
631			`func ParseCIDR(s string) (IP, *IPNet, error) {`
632			`i := byteIndex(s, '/')`
633			`if i < 0 {`
634			`return nil, nil, &ParseError{"CIDR address", s}`
635			`}`
636			`ipstr, maskstr := s[:i], s[i+1:]`
637			`iplen := IPv4len`
638			`ip := parseIPv4(ipstr)`
639			`if ip == nil {`
640			`iplen = IPv6len`
641			`ip = parseIPv6(ipstr)`
642			`}`
643			`n, i, ok := dtoi(maskstr, 0)`
644			`if ip == nil \|\| !ok \|\| i != len(maskstr) \|\| n < 0 \|\| n > 8*iplen {`
645			`return nil, nil, &ParseError{"CIDR address", s}`
646			`}`
647			`m := CIDRMask(n, 8*iplen)`
648			`return ip, &IPNet{ip.Mask(m), m}, nil`
649			`}`