| // 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 "errors" |
| |
| // 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 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 |
| } |
| |
| // IsInterfaceLocalMulticast 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 |
| } |
| } |
| |
| 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 "<nil>" |
| } |
| |
| // If IPv4, use dotted notation. |
| if p4 := p.To4(); len(p4) == IPv4len { |
| return uitoa(uint(p4[0])) + "." + |
| uitoa(uint(p4[1])) + "." + |
| uitoa(uint(p4[2])) + "." + |
| uitoa(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 |
| 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) |
| } |
| |
| // 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. |
| func (ip IP) MarshalText() ([]byte, error) { |
| if len(ip) == 0 { |
| return []byte(""), nil |
| } |
| if len(ip) != IPv4len && len(ip) != IPv6len { |
| return nil, errors.New("invalid IP address") |
| } |
| 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{"IP address", s} |
| } |
| *ip = x |
| return nil |
| } |
| |
| // 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 { |
| if len(m) == 0 { |
| return "<nil>" |
| } |
| buf := make([]byte, len(m)*2) |
| for i, b := range m { |
| buf[i*2], buf[i*2+1] = hexDigit[b>>4], hexDigit[b&0xf] |
| } |
| return string(buf) |
| } |
| |
| 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 "192.168.100.1/24" |
| // 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 "<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 |
| 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]) |
| } |
| |
| // parseIPv6 parses s as a literal IPv6 address described in RFC 4291 |
| // and RFC 5952. It can also parse a literal scoped IPv6 address with |
| // zone identifier which is described in RFC 4007 when zoneAllowed is |
| // true. |
| func parseIPv6(s string, zoneAllowed bool) (ip IP, zone string) { |
| ip = make(IP, IPv6len) |
| ellipsis := -1 // position of ellipsis in p |
| i := 0 // index in string s |
| |
| if zoneAllowed { |
| s, zone = splitHostZone(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 ip, zone |
| } |
| } |
| |
| // 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, zone |
| } |
| |
| // 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, zone |
| } |
| if j+IPv4len > IPv6len { |
| // Not enough room. |
| return nil, zone |
| } |
| ip4 := parseIPv4(s[i:]) |
| if ip4 == nil { |
| return nil, zone |
| } |
| ip[j] = ip4[12] |
| ip[j+1] = ip4[13] |
| ip[j+2] = ip4[14] |
| ip[j+3] = ip4[15] |
| i = len(s) |
| j += IPv4len |
| break |
| } |
| |
| // Save this 16-bit chunk. |
| ip[j] = byte(n >> 8) |
| ip[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, zone |
| } |
| i++ |
| |
| // Look for ellipsis. |
| if s[i] == ':' { |
| if ellipsis >= 0 { // already have one |
| return nil, zone |
| } |
| ellipsis = j |
| if i++; i == len(s) { // can be at end |
| break |
| } |
| } |
| } |
| |
| // Must have used entire string. |
| if i != len(s) { |
| return nil, zone |
| } |
| |
| // If didn't parse enough, expand ellipsis. |
| if j < IPv6len { |
| if ellipsis < 0 { |
| return nil, zone |
| } |
| n := IPv6len - j |
| for k := j - 1; k >= ellipsis; k-- { |
| ip[k+n] = ip[k] |
| } |
| for k := ellipsis + n - 1; k >= ellipsis; k-- { |
| ip[k] = 0 |
| } |
| } else if ellipsis >= 0 { |
| // Ellipsis must represent at least one 0 group. |
| return nil, zone |
| } |
| return ip, zone |
| } |
| |
| // 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 |
| } |
| |
| // 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 { |
| for i := 0; i < len(s); i++ { |
| switch s[i] { |
| case '.': |
| return parseIPv4(s) |
| case ':': |
| ip, _ := parseIPv6(s, false) |
| return ip |
| } |
| } |
| return nil |
| } |
| |
| // 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} |
| } |
| addr, mask := s[:i], s[i+1:] |
| iplen := IPv4len |
| ip := parseIPv4(addr) |
| if ip == nil { |
| iplen = IPv6len |
| ip, _ = parseIPv6(addr, false) |
| } |
| n, i, ok := dtoi(mask, 0) |
| if ip == nil || !ok || i != len(mask) || n < 0 || n > 8*iplen { |
| return nil, nil, &ParseError{"CIDR address", s} |
| } |
| m := CIDRMask(n, 8*iplen) |
| return ip, &IPNet{IP: ip.Mask(m), Mask: m}, nil |
| } |