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-rw-r--r--src/lib/net/ip.go431
1 files changed, 431 insertions, 0 deletions
diff --git a/src/lib/net/ip.go b/src/lib/net/ip.go
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+++ b/src/lib/net/ip.go
@@ -0,0 +1,431 @@
+// 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
+ }
+
+ // 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 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+1] == ':' {
+ 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; 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)
+}
+
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-03 03:39:54 +0000