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mv src/lib to src/pkg
tests: all.bash passes, gobuild still works, godoc still works. R=rsc OCL=30096 CL=30102
This commit is contained in:
Rob Pike
parent
bf5c0c957c
commit
d90e7cbac6
391 changed files with 14 additions and 48 deletions
421
src/pkg/net/ip.go
Normal file
421
src/pkg/net/ip.go
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@ -0,0 +1,421 @@
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// IP address manipulations
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//
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// IPv4 addresses are 4 bytes; IPv6 addresses are 16 bytes.
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// An IPv4 address can be converted to an IPv6 address by
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// adding a canonical prefix (10 zeros, 2 0xFFs).
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// This library accepts either size of byte array but always
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// returns 16-byte addresses.
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package net
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import (
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"net"
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)
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// IP address lengths (bytes).
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const (
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IPv4len = 4;
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IPv6len = 16
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)
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// An IP is a single IP address, an array of bytes.
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// Functions in this package accept either 4-byte (IP v4)
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// or 16-byte (IP v6) arrays as input. Unless otherwise
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// specified, functions in this package always return
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// IP addresses in 16-byte form using the canonical
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// embedding.
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//
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// Note that in this documentation, referring to an
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// IP address as an IPv4 address or an IPv6 address
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// is a semantic property of the address, not just the
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// length of the byte array: a 16-byte array can still
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// be an IPv4 address.
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type IP []byte;
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// An IP mask is an IP address.
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type IPMask []byte;
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// IPv4 returns the IP address (in 16-byte form) of the
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// IPv4 address a.b.c.d.
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func IPv4(a, b, c, d byte) IP {
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p := make(IP, IPv6len);
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for i := 0; i < 10; i++ {
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p[i] = 0
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}
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p[10] = 0xff;
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p[11] = 0xff;
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p[12] = a;
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p[13] = b;
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p[14] = c;
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p[15] = d;
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return p
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}
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// Well-known IPv4 addresses
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var (
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IPv4bcast = IPv4(255, 255, 255, 255); // broadcast
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IPv4allsys = IPv4(224, 0, 0, 1); // all systems
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IPv4allrouter = IPv4(224, 0, 0, 2); // all routers
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IPv4zero = IPv4(0, 0, 0, 0); // all zeros
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)
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// Well-known IPv6 addresses
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var (
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IPzero = make(IP, IPv6len); // all zeros
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)
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// Is p all zeros?
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func isZeros(p IP) bool {
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for i := 0; i < len(p); i++ {
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if p[i] != 0 {
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return false
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}
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}
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return true
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}
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// To4 converts the IPv4 address ip to a 4-byte representation.
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// If ip is not an IPv4 address, To4 returns nil.
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func (ip IP) To4() IP {
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if len(ip) == IPv4len {
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return ip
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}
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if len(ip) == IPv6len
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&& isZeros(ip[0:10])
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&& ip[10] == 0xff
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&& ip[11] == 0xff {
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return ip[12:16]
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}
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return nil
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}
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// To16 converts the IP address ip to a 16-byte representation.
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// If ip is not an IP address (it is the wrong length), To16 returns nil.
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func (ip IP) To16() IP {
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if len(ip) == IPv4len {
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return IPv4(ip[0], ip[1], ip[2], ip[3])
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}
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if len(ip) == IPv6len {
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return ip
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}
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return nil
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}
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// Default route masks for IPv4.
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var (
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classAMask = IPMask(IPv4(0xff, 0, 0, 0));
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classBMask = IPMask(IPv4(0xff, 0xff, 0, 0));
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classCMask = IPMask(IPv4(0xff, 0xff, 0xff, 0));
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)
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// DefaultMask returns the default IP mask for the IP address ip.
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// Only IPv4 addresses have default masks; DefaultMask returns
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// nil if ip is not a valid IPv4 address.
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func (ip IP) DefaultMask() IPMask {
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if ip = ip.To4(); ip == nil {
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return nil
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}
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switch true {
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case ip[0] < 0x80:
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return classAMask;
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case ip[0] < 0xC0:
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return classBMask;
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default:
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return classCMask;
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}
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return nil; // not reached
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}
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// Mask returns the result of masking the IP address ip with mask.
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func (ip IP) Mask(mask IPMask) IP {
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n := len(ip);
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if n != len(mask) {
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return nil
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}
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out := make(IP, n);
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for i := 0; i < n; i++ {
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out[i] = ip[i] & mask[i];
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}
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return out
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}
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// Convert i to decimal string.
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func itod(i uint) string {
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if i == 0 {
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return "0"
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}
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// Assemble decimal in reverse order.
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var b [32]byte;
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bp := len(b);
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for ; i > 0; i /= 10 {
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bp--;
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b[bp] = byte(i%10) + '0'
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}
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return string(b[bp:len(b)])
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}
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// Convert i to hexadecimal string.
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func itox(i uint) string {
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if i == 0 {
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return "0"
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}
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// Assemble hexadecimal in reverse order.
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var b [32]byte;
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bp := len(b);
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for ; i > 0; i /= 16 {
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bp--;
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b[bp] = "0123456789abcdef"[byte(i%16)]
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}
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return string(b[bp:len(b)])
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}
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// String returns the string form of the IP address ip.
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// If the address is an IPv4 address, the string representation
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// is dotted decimal ("74.125.19.99"). Otherwise the representation
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// is IPv6 ("2001:4860:0:2001::68").
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func (ip IP) String() string {
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p := ip;
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// If IPv4, use dotted notation.
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if p4 := p.To4(); len(p4) == 4 {
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return itod(uint(p4[0]))+"."
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+itod(uint(p4[1]))+"."
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+itod(uint(p4[2]))+"."
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+itod(uint(p4[3]))
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}
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if len(p) != IPv6len {
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return "?"
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}
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// Find longest run of zeros.
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e0 := -1;
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e1 := -1;
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for i := 0; i < 16; i+=2 {
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j := i;
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for j < 16 && p[j] == 0 && p[j+1] == 0 {
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j += 2
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}
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if j > i && j - i > e1 - e0 {
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e0 = i;
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e1 = j
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}
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}
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// Print with possible :: in place of run of zeros
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var s string;
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for i := 0; i < 16; i += 2 {
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if i == e0 {
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s += "::";
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i = e1;
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if i >= 16 {
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break
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}
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} else if i > 0 {
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s += ":"
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}
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s += itox((uint(p[i])<<8) | uint(p[i+1]))
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}
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return s
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}
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// If mask is a sequence of 1 bits followed by 0 bits,
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// return the number of 1 bits.
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func simpleMaskLength(mask IPMask) int {
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var i int;
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for i = 0; i < len(mask); i++ {
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if mask[i] != 0xFF {
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break
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}
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}
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n := 8*i;
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v := mask[i];
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for v & 0x80 != 0 {
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n++;
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v <<= 1
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}
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if v != 0 {
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return -1
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}
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for i++; i < len(mask); i++ {
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if mask[i] != 0 {
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return -1
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}
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}
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return n
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}
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// String returns the string representation of mask.
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// If the mask is in the canonical form--ones followed by zeros--the
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// string representation is just the decimal number of ones.
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// If the mask is in a non-canonical form, it is formatted
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// as an IP address.
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func (mask IPMask) String() string {
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switch len(mask) {
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case 4:
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n := simpleMaskLength(mask);
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if n >= 0 {
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return itod(uint(n+(IPv6len-IPv4len)*8))
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}
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case 16:
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n := simpleMaskLength(mask);
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if n >= 0 {
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return itod(uint(n))
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}
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}
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return IP(mask).String();
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}
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// Parse IPv4 address (d.d.d.d).
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func parseIPv4(s string) IP {
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var p [IPv4len]byte;
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i := 0;
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for j := 0; j < IPv4len; j++ {
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if j > 0 {
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if s[i] != '.' {
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return nil
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}
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i++;
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}
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var (
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n int;
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ok bool
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)
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n, i, ok = dtoi(s, i);
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if !ok || n > 0xFF {
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return nil
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}
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p[j] = byte(n)
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}
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if i != len(s) {
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return nil
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}
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return IPv4(p[0], p[1], p[2], p[3])
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}
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// Parse IPv6 address. Many forms.
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// The basic form is a sequence of eight colon-separated
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// 16-bit hex numbers separated by colons,
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// as in 0123:4567:89ab:cdef:0123:4567:89ab:cdef.
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// Two exceptions:
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// * A run of zeros can be replaced with "::".
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// * The last 32 bits can be in IPv4 form.
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// Thus, ::ffff:1.2.3.4 is the IPv4 address 1.2.3.4.
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func parseIPv6(s string) IP {
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p := make(IP, 16);
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ellipsis := -1; // position of ellipsis in p
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i := 0; // index in string s
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// Might have leading ellipsis
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if len(s) >= 2 && s[0] == ':' && s[1] == ':' {
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ellipsis = 0;
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i = 2;
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// Might be only ellipsis
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if i == len(s) {
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return p
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}
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}
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// Loop, parsing hex numbers followed by colon.
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j := 0;
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L: for j < IPv6len {
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// Hex number.
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n, i1, ok := xtoi(s, i);
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if !ok || n > 0xFFFF {
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return nil
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}
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// If followed by dot, might be in trailing IPv4.
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if i1 < len(s) && s[i1] == '.' {
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if ellipsis < 0 && j != IPv6len - IPv4len {
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// Not the right place.
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return nil
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}
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if j+IPv4len > IPv6len {
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// Not enough room.
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return nil
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}
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p4 := parseIPv4(s[i:len(s)]);
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if p4 == nil {
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return nil
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}
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// BUG: p[j:j+4] = p4
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p[j] = p4[12];
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p[j+1] = p4[13];
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p[j+2] = p4[14];
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p[j+3] = p4[15];
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i = len(s);
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j += 4;
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break
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}
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// Save this 16-bit chunk.
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p[j] = byte(n>>8);
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p[j+1] = byte(n);
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j += 2;
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// Stop at end of string.
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i = i1;
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if i == len(s) {
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break
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}
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// Otherwise must be followed by colon and more.
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if s[i] != ':' && i+1 == len(s) {
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return nil
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}
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i++;
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// Look for ellipsis.
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if s[i] == ':' {
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if ellipsis >= 0 { // already have one
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return nil
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}
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ellipsis = j;
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if i++; i == len(s) { // can be at end
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break
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}
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}
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}
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// Must have used entire string.
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if i != len(s) {
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return nil
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}
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// If didn't parse enough, expand ellipsis.
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if j < IPv6len {
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if ellipsis < 0 {
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return nil
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}
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n := IPv6len - j;
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for k := j-1; k >= ellipsis; k-- {
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p[k+n] = p[k]
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}
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for k := ellipsis+n-1; k>=ellipsis; k-- {
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p[k] = 0
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}
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}
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return p
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}
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// ParseIP parses s as an IP address, returning the result.
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// The string s can be in dotted decimal ("74.125.19.99")
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// or IPv6 ("2001:4860:0:2001::68") form.
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// If s is not a valid textual representation of an IP address,
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// ParseIP returns nil.
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func ParseIP(s string) IP {
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p := parseIPv4(s);
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if p != nil {
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return p
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}
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return parseIPv6(s)
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}
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