src/lib/net/ip.go - go - Git at Google

 // 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 ip

 export const (
 	IPv4len = 4;
 	IPv6len = 16
 )

 // Make the 4 bytes into an IPv4 address (in IPv6 form)
 func MakeIPv4(a, b, c, d byte) *[]byte {
 	p := new([]byte, 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
 }

 // Well-known IP addresses
 export var IPv4bcast, IPv4allsys, IPv4allrouter, IPv4prefix, IPallbits, IPnoaddr *[]byte

 func init() {
 	IPv4bcast = MakeIPv4(0xff, 0xff, 0xff, 0xff);
 	IPv4allsys = MakeIPv4(0xe0, 0x00, 0x00, 0x01);
 	IPv4allrouter = MakeIPv4(0xe0, 0x00, 0x00, 0x02);
 	IPv4prefix = MakeIPv4(0, 0, 0, 0);
 	IPallbits = new([]byte, IPv6len);
 	for i := 0; i < IPv6len; i++ {
 		IPallbits[i] = 0xff
 	}
 	IPnoaddr = new([]byte, IPv6len);	// zeroed
 }

 // Is p all zeros?
 func IsZeros(p *[]byte) bool {
 	for i := 0; i < len(p); i++ {
 		if p[i] != 0 {
 			return false
 		}
 	}
 	return true
 }

 // Is p an IPv4 address (perhaps in IPv6 form)?
 // If so, return the 4-byte V4 array.
 export func ToIPv4(p *[]byte) *[]byte {
 	if len(p) == IPv4len {
 		return p
 	}
 	if len(p) == IPv6len
 	&& IsZeros(p[0:10])
 	&& p[10] == 0xff
 	&& p[11] == 0xff {
 		return p[12:16]
 	}
 	return nil
 }

 // Convert p to IPv6 form.
 export func ToIPv6(p *[]byte) *[]byte {
 	if len(p) == IPv4len {
 		return MakeIPv4(p[0], p[1], p[2], p[3])
 	}
 	if len(p) == IPv6len {
 		return p
 	}
 	return nil
 }

 // Default route masks for IPv4.
 export var (
 	ClassAMask = MakeIPv4(0xff, 0, 0, 0);
 	ClassBMask = MakeIPv4(0xff, 0xff, 0, 0);
 	ClassCMask = MakeIPv4(0xff, 0xff, 0xff, 0);
 )

 export func DefaultMask(p *[]byte) *[]byte {
 	if p = ToIPv4(p); p == nil {
 		return nil
 	}
 	switch true {
 	case p[0] < 0x80:
 		return ClassAMask;
 	case p[0] < 0xC0:
 		return ClassBMask;
 	default:
 		return ClassCMask;
 	}
 	return nil;	// not reached
 }

 // Apply mask to ip, returning new address.
 export func Mask(ip *[]byte, mask *[]byte) *[]byte {
 	n := len(ip)
 	if n != len(mask) {
 		return nil
 	}
 	out := new([]byte, 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:len(b)])
 	return string((&b)[bp:len(b)])
 }

 // 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:len(b)])
 	return string((&b)[bp:len(b)])
 }

 // Convert IP address to string.
 export func IPToString(p *[]byte) string {
 	// If IPv4, use dotted notation.
 	if p4 := ToIPv4(p); p4 != nil {
 		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
 		}
 	}

 	// 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 *[]byte) int {
 	var i int
 	for i = 0; i < len(mask); i++ {
 		if mask[i] != 0xFF {
 			break
 		}
 	}
 	n := 8*i;
 	v := mask[i]
 	for v & 0x80 != 0 {
 		n++
 		v <<= 1
 	}
 	if v != 0 {
 		return -1
 	}
 	for i++; i < len(mask); i++ {
 		if mask[i] != 0 {
 			return -1
 		}
 	}
 	return n
 }

 export func MaskToString(mask *[]byte) 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 >= 0 {
 			return itod(uint(n))
 		}
 	}
 	return IPToString(mask)
 }

 // Parsing.

 // Bigger than we need, not too big to worry about overflow
 const Big = 0xFFFFFF

 // Decimal to integer starting at &s[i].
 // Returns number, new offset, success.
 func dtoi(s string, i int) (n int, i1 int, ok bool) {
 	if len(s) <= i || s[i] < '0' || s[i] > '9' {
 		return 0, i, false
 	}
 	n = 0;
 	for ; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
 		n = n*10 + int(s[i] - '0')
 		if n >= Big {
 			return 0, i, false
 		}
 	}
 	return n, i, true
 }

 // Is b a hex digit?
 func ishex(b byte) bool {
 	return '0' <= b && b <= '9'
 		|| 'a' <= b && b <= 'f'
 		|| 'A' <= b && b <= 'F'
 }

 // Hexadecimal to integer starting at &s[i].
 // Returns number, new offset, success.
 func xtoi(s string, i int) (n int, i1 int, ok bool) {
 	if len(s) <= i || !ishex(s[i]) {
 		return 0, i, false
 	}

 	n = 0;
 	for ; i < len(s) && ishex(s[i]); i++ {
 		n *= 16
 		if '0' <= s[i] && s[i] <= '9' {
 			n += int(s[i] - '0')
 		} else if 'a' <= s[i] && s[i] <= 'f' {
 			n += int(s[i] - 'a') + 10
 		} else {
 			n += int(s[i] -'A') + 10
 		}
 		if n >= Big {
 			return 0, i, false
 		}
 	}
 	return n, i, true
 }

 // Parse IPv4 address (d.d.d.d).
 func ParseIPv4(s string) *[]byte {
 	var p [IPv4len]byte
 	i := 0
 	for j := 0; j < IPv4len; j++ {
 		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 MakeIPv4(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) *[]byte {
 	p := new([]byte, 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:len(s)]);
 			if p4 == nil {
 				return nil
 			}
 			// BUG: p[j:j+4] = p4
 			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
 }

 export func ParseIP(s string) *[]byte {
 	p := ParseIPv4(s)
 	if p != nil {
 		return p
 	}
 	return ParseIPv6(s)
 }
	// 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 ip

	export const (
	IPv4len = 4;
	IPv6len = 16
	)

	// Make the 4 bytes into an IPv4 address (in IPv6 form)
	func MakeIPv4(a, b, c, d byte) *[]byte {
	p := new([]byte, 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
	}

	// Well-known IP addresses
	export var IPv4bcast, IPv4allsys, IPv4allrouter, IPv4prefix, IPallbits, IPnoaddr *[]byte

	func init() {
	IPv4bcast = MakeIPv4(0xff, 0xff, 0xff, 0xff);
	IPv4allsys = MakeIPv4(0xe0, 0x00, 0x00, 0x01);
	IPv4allrouter = MakeIPv4(0xe0, 0x00, 0x00, 0x02);
	IPv4prefix = MakeIPv4(0, 0, 0, 0);
	IPallbits = new([]byte, IPv6len);
	for i := 0; i < IPv6len; i++ {
	IPallbits[i] = 0xff
	}
	IPnoaddr = new([]byte, IPv6len); // zeroed
	}

	// Is p all zeros?
	func IsZeros(p *[]byte) bool {
	for i := 0; i < len(p); i++ {
	if p[i] != 0 {
	return false
	}
	}
	return true
	}

	// Is p an IPv4 address (perhaps in IPv6 form)?
	// If so, return the 4-byte V4 array.
	export func ToIPv4(p []byte) []byte {
	if len(p) == IPv4len {
	return p
	}
	if len(p) == IPv6len
	&& IsZeros(p[0:10])
	&& p[10] == 0xff
	&& p[11] == 0xff {
	return p[12:16]
	}
	return nil
	}

	// Convert p to IPv6 form.
	export func ToIPv6(p []byte) []byte {
	if len(p) == IPv4len {
	return MakeIPv4(p[0], p[1], p[2], p[3])
	}
	if len(p) == IPv6len {
	return p
	}
	return nil
	}

	// Default route masks for IPv4.
	export var (
	ClassAMask = MakeIPv4(0xff, 0, 0, 0);
	ClassBMask = MakeIPv4(0xff, 0xff, 0, 0);
	ClassCMask = MakeIPv4(0xff, 0xff, 0xff, 0);
	)

	export func DefaultMask(p []byte) []byte {
	if p = ToIPv4(p); p == nil {
	return nil
	}
	switch true {
	case p[0] < 0x80:
	return ClassAMask;
	case p[0] < 0xC0:
	return ClassBMask;
	default:
	return ClassCMask;
	}
	return nil; // not reached
	}

	// Apply mask to ip, returning new address.
	export func Mask(ip []byte, mask []byte) *[]byte {
	n := len(ip)
	if n != len(mask) {
	return nil
	}
	out := new([]byte, 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:len(b)])
	return string((&b)[bp:len(b)])
	}

	// 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:len(b)])
	return string((&b)[bp:len(b)])
	}

	// Convert IP address to string.
	export func IPToString(p *[]byte) string {
	// If IPv4, use dotted notation.
	if p4 := ToIPv4(p); p4 != nil {
	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
	}
	}

	// 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 *[]byte) int {
	var i int
	for i = 0; i < len(mask); i++ {
	if mask[i] != 0xFF {
	break
	}
	}
	n := 8*i;
	v := mask[i]
	for v & 0x80 != 0 {
	n++
	v <<= 1
	}
	if v != 0 {
	return -1
	}
	for i++; i < len(mask); i++ {
	if mask[i] != 0 {
	return -1
	}
	}
	return n
	}

	export func MaskToString(mask *[]byte) 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 >= 0 {
	return itod(uint(n))
	}
	}
	return IPToString(mask)
	}

	// Parsing.

	// Bigger than we need, not too big to worry about overflow
	const Big = 0xFFFFFF

	// Decimal to integer starting at &s[i].
	// Returns number, new offset, success.
	func dtoi(s string, i int) (n int, i1 int, ok bool) {
	if len(s) <= i \|\| s[i] < '0' \|\| s[i] > '9' {
	return 0, i, false
	}
	n = 0;
	for ; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
	n = n*10 + int(s[i] - '0')
	if n >= Big {
	return 0, i, false
	}
	}
	return n, i, true
	}

	// Is b a hex digit?
	func ishex(b byte) bool {
	return '0' <= b && b <= '9'
	\|\| 'a' <= b && b <= 'f'
	\|\| 'A' <= b && b <= 'F'
	}

	// Hexadecimal to integer starting at &s[i].
	// Returns number, new offset, success.
	func xtoi(s string, i int) (n int, i1 int, ok bool) {
	if len(s) <= i \|\| !ishex(s[i]) {
	return 0, i, false
	}

	n = 0;
	for ; i < len(s) && ishex(s[i]); i++ {
	n *= 16
	if '0' <= s[i] && s[i] <= '9' {
	n += int(s[i] - '0')
	} else if 'a' <= s[i] && s[i] <= 'f' {
	n += int(s[i] - 'a') + 10
	} else {
	n += int(s[i] -'A') + 10
	}
	if n >= Big {
	return 0, i, false
	}
	}
	return n, i, true
	}

	// Parse IPv4 address (d.d.d.d).
	func ParseIPv4(s string) *[]byte {
	var p [IPv4len]byte
	i := 0
	for j := 0; j < IPv4len; j++ {
	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 MakeIPv4(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) *[]byte {
	p := new([]byte, 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:len(s)]);
	if p4 == nil {
	return nil
	}
	// BUG: p[j:j+4] = p4
	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
	}

	export func ParseIP(s string) *[]byte {
	p := ParseIPv4(s)
	if p != nil {
	return p
	}
	return ParseIPv6(s)
	}