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//------------------------------------------------------------------------------
// <copyright file="_IPv6Address.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Net;
using System.Text;
namespace System {
// The class designed as to keep minimal the working set of Uri class.
// The idea is to stay with static helper methods and strings
internal static class IPv6AddressHelper {
// fields
private const int NumberOfLabels = 8;
// Upper case hex, zero padded to 4 characters
private const string LegacyFormat = "{0:X4}:{1:X4}:{2:X4}:{3:X4}:{4:X4}:{5:X4}:{6:X4}:{7:X4}";
// Lower case hex, no leading zeros
private const string CanonicalNumberFormat = "{0:x}";
private const string EmbeddedIPv4Format = ":{0:d}.{1:d}.{2:d}.{3:d}";
private const string Separator = ":";
// methods
internal static string ParseCanonicalName(string str, int start, ref bool isLoopback, ref string scopeId) {
unsafe {
// Allocate one additional element due to off-by-one bug in the Parse() method because of invalid logic
// in the InternalIsValid() method. We allow the bug fix to be turned off for app-compat reasons via
// the registry key 'UseStrictIPv6AddressParsing'. But if the bug fix is turned off we still don't
// want to write into unallocated memory.
ushort *numbers = stackalloc ushort[NumberOfLabels + 1];
// optimized zeroing of 8 shorts = 2 longs
((long*)numbers)[0] = 0L;
((long*)numbers)[1] = 0L;
isLoopback = Parse(str, numbers, start, ref scopeId);
return '[' + CreateCanonicalName(numbers) + ']';
}
}
internal unsafe static string CreateCanonicalName(ushort *numbers) {
if (UriParser.ShouldUseLegacyV2Quirks) {
return string.Format(CultureInfo.InvariantCulture, LegacyFormat,
numbers[0], numbers[1], numbers[2], numbers[3],
numbers[4], numbers[5], numbers[6], numbers[7]);
}
// RFC 5952 Sections 4 & 5 - Compressed, lower case, with possible embedded IPv4 addresses.
// Start to finish, inclusive. <-1, -1> for no compression
KeyValuePair<int, int> range = FindCompressionRange(numbers);
bool ipv4Embedded = ShouldHaveIpv4Embedded(numbers);
StringBuilder builder = new StringBuilder();
for (int i = 0; i < NumberOfLabels; i++) {
if (ipv4Embedded && i == (NumberOfLabels - 2)) {
// Write the remaining digits as an IPv4 address
builder.Append(string.Format(CultureInfo.InvariantCulture, EmbeddedIPv4Format,
numbers[i] >> 8, numbers[i] & 0xFF, numbers[i + 1] >> 8, numbers[i + 1] & 0xFF));
break;
}
// Compression; 1::1, ::1, 1::
if (range.Key == i) { // Start compression, add :
builder.Append(Separator);
}
if (range.Key <= i && range.Value == (NumberOfLabels - 1)) { // Remainder compressed; 1::
builder.Append(Separator);
break;
}
if (range.Key <= i && i <= range.Value) {
continue; // Compressed
}
if (i != 0) {
builder.Append(Separator);
}
builder.Append(string.Format(CultureInfo.InvariantCulture, CanonicalNumberFormat, numbers[i]));
}
return builder.ToString();
}
// RFC 5952 Section 4.2.3
// Longest consecutive sequence of zero segments, minimum 2.
// On equal, first sequence wins.
// <-1, -1> for no compression.
private unsafe static KeyValuePair<int, int> FindCompressionRange(ushort* numbers) {
int longestSequenceLength = 0;
int longestSequenceStart = -1;
int currentSequenceLength = 0;
for (int i = 0; i < NumberOfLabels; i++) {
if (numbers[i] == 0) { // In a sequence
currentSequenceLength++;
if (currentSequenceLength > longestSequenceLength) {
longestSequenceLength = currentSequenceLength;
longestSequenceStart = i - currentSequenceLength + 1;
}
}
else {
currentSequenceLength = 0;
}
}
if (longestSequenceLength >= 2) {
return new KeyValuePair<int, int>(longestSequenceStart,
longestSequenceStart + longestSequenceLength - 1);
}
return new KeyValuePair<int, int>(-1, -1); // No compression
}
// Returns true if the IPv6 address should be formated with an embedded IPv4 address:
// ::192.168.1.1
private unsafe static bool ShouldHaveIpv4Embedded(ushort* numbers) {
// 0:0 : 0:0 : x:x : x.x.x.x
if (numbers[0] == 0 && numbers[1] == 0 && numbers[2] == 0 && numbers[3] == 0 && numbers[6] != 0) {
// RFC 5952 Section 5 - 0:0 : 0:0 : 0:[0 | FFFF] : x.x.x.x
if (numbers[4] == 0 && (numbers[5] == 0 || numbers[5] == 0xFFFF)) {
return true;
}
// SIIT - 0:0 : 0:0 : FFFF:0 : x.x.x.x
else if (numbers[4] == 0xFFFF && numbers[5] == 0) {
return true;
}
}
// ISATAP
if (numbers[4] == 0 && numbers[5] == 0x5EFE) {
return true;
}
return false;
}
//
// InternalIsValid
//
// Determine whether a name is a valid IPv6 address. Rules are:
//
// * 8 groups of 16-bit hex numbers, separated by ':'
// * a *single* run of zeros can be compressed using the symbol '::'
// * an optional string of a ScopeID delimited by '%'
// * an optional (last) 1 or 2 character prefix length field delimited by '/'
// * the last 32 bits in an address can be represented as an IPv4 address
//
// Inputs:
// <argument> name
// Domain name field of a URI to check for pattern match with
// IPv6 address
// validateStrictAddress: if set to true, it expects strict ipv6 address. Otherwise it expects
// part of the string in ipv6 format.
//
// Outputs:
// Nothing
//
// Assumes:
// the correct name is terminated by ']' character
//
// Returns:
// true if <name> has IPv6 format/ipv6 address based on validateStrictAddress, else false
//
// Throws:
// Nothing
//
// Remarks: MUST NOT be used unless all input indexes are verified and trusted.
// start must be next to '[' position, or error is reported
unsafe private static bool InternalIsValid(char* name, int start, ref int end, bool validateStrictAddress) {
int sequenceCount = 0;
int sequenceLength = 0;
bool haveCompressor = false;
bool haveIPv4Address = false;
bool havePrefix = false;
bool expectingNumber = true;
int lastSequence = 1;
// Starting with a colon character is only valid if another colon follows.
if (name[start] == ':' && (start + 1 >= end || name[start + 1] != ':') && ServicePointManager.UseStrictIPv6AddressParsing) {
return false;
}
int i;
for (i = start; i < end; ++i) {
if (havePrefix ? (name[i] >= '0' && name[i] <= '9') : Uri.IsHexDigit(name[i])) {
++sequenceLength;
expectingNumber = false;
} else {
if (sequenceLength > 4) {
return false;
}
if (sequenceLength != 0) {
++sequenceCount;
lastSequence = i - sequenceLength;
}
switch (name[i]) {
case '%': while (true) {
//accept anything in scopeID
if (++i == end) {
// no closing ']', fail
return false;
}
if (name[i] == ']') {
goto case ']';
}
else if (name[i] == '/') {
goto case '/';
}
}
case ']': start = i;
i = end;
//this will make i = end+1
continue;
case ':':
if ((i > 0) && (name[i - 1] == ':')) {
if (haveCompressor) {
//
// can only have one per IPv6 address
//
return false;
}
haveCompressor = true;
expectingNumber = false;
} else {
expectingNumber = true;
}
break;
case '/':
if (validateStrictAddress) {
return false;
}
if ((sequenceCount == 0) || havePrefix) {
return false;
}
havePrefix = true;
expectingNumber = true;
break;
case '.':
if (haveIPv4Address) {
return false;
}
i = end;
if (!IPv4AddressHelper.IsValid(name, lastSequence, ref i, true, false, false)) {
return false;
}
// ipv4 address takes 2 slots in ipv6 address, one was just counted meeting the '.'
++sequenceCount;
haveIPv4Address = true;
--i; // it will be incremented back on the next loop
break;
default:
return false;
}
sequenceLength = 0;
}
}
//
// if the last token was a prefix, check number of digits
//
if (havePrefix && ((sequenceLength < 1) || (sequenceLength > 2))) {
return false;
}
//
// these sequence counts are -1 because it is implied in end-of-sequence
//
int expectedSequenceCount = 8 + (havePrefix ? 1 : 0);
if (!expectingNumber && (sequenceLength <= 4) && (haveCompressor ? (sequenceCount < expectedSequenceCount) : (sequenceCount == expectedSequenceCount)))
{
if (i == end + 1)
{
// ']' was found
end = start+1;
return true;
}
return false;
}
return false;
}
//
// IsValid
//
// Determine whether a name is a valid IPv6 address. Rules are:
//
// * 8 groups of 16-bit hex numbers, separated by ':'
// * a *single* run of zeros can be compressed using the symbol '::'
// * an optional string of a ScopeID delimited by '%'
// * an optional (last) 1 or 2 character prefix length field delimited by '/'
// * the last 32 bits in an address can be represented as an IPv4 address
//
// Inputs:
// <argument> name
// Domain name field of a URI to check for pattern match with
// IPv6 address
//
// Outputs:
// Nothing
//
// Assumes:
// the correct name is terminated by ']' character
//
// Returns:
// true if <name> has IPv6 format, else false
//
// Throws:
// Nothing
//
// Remarks: MUST NOT be used unless all input indexes are are verified and trusted.
// start must be next to '[' position, or error is reported
internal unsafe static bool IsValid(char* name, int start, ref int end) {
return InternalIsValid(name, start, ref end, false);
}
//
// IsValidStrict
//
// Determine whether a name is a valid IPv6 address. Rules are:
//
// * 8 groups of 16-bit hex numbers, separated by ':'
// * a *single* run of zeros can be compressed using the symbol '::'
// * an optional string of a ScopeID delimited by '%'
// * the last 32 bits in an address can be represented as an IPv4 address
//
// Difference between IsValid() and IsValidStrict() is that IsValid() expects part of the string to
// be ipv6 address where as IsValidStrict() expects strict ipv6 address.
//
// Inputs:
// <argument> name
// IPv6 address in string format
//
// Outputs:
// Nothing
//
// Assumes:
// the correct name is terminated by ']' character
//
// Returns:
// true if <name> is IPv6 address, else false
//
// Throws:
// Nothing
//
// Remarks: MUST NOT be used unless all input indexes are verified and trusted.
// start must be next to '[' position, or error is reported
internal unsafe static bool IsValidStrict(char* name, int start, ref int end) {
return InternalIsValid(name, start, ref end, true);
}
//
// Parse
//
// Convert this IPv6 address into a sequence of 8 16-bit numbers
//
// Inputs:
// <member> Name
// The validated IPv6 address
//
// Outputs:
// <member> numbers
// Array filled in with the numbers in the IPv6 groups
//
// <member> PrefixLength
// Set to the number after the prefix separator (/) if found
//
// Assumes:
// <Name> has been validated and contains only hex digits in groups of
// 16-bit numbers, the characters ':' and '/', and a possible IPv4
// address
//
// Returns:
// true if this is a loopback, false otherwise. There is no falure indication as the sting must be a valid one.
//
// Throws:
// Nothing
//
unsafe internal static bool Parse(string address, ushort *numbers, int start, ref string scopeId) {
int number = 0;
int index = 0;
int compressorIndex = -1;
bool numberIsValid = true;
//This used to be a class instance member but have not been used so far
int PrefixLength = 0;
if (address[start] == '[') {
++start;
}
for (int i = start; i < address.Length && address[i] != ']'; ) {
ValidateIndex(index);
switch (address[i]) {
case '%':
if (numberIsValid) {
numbers[index++] = (ushort)number;
numberIsValid = false;
}
start = i;
for (++i; address[i] != ']' && address[i] != '/'; ++i) {
;
}
scopeId = address.Substring(start, i-start);
// ignore prefix if any
for (; address[i] != ']'; ++i) {
;
}
break;
case ':':
numbers[index++] = (ushort)number;
number = 0;
++i;
if (address[i] == ':') {
compressorIndex = index;
++i;
} else if ((compressorIndex < 0) && (index < 6)) {
//
// no point checking for IPv4 address if we don't
// have a compressor or we haven't seen 6 16-bit
// numbers yet
//
break;
}
//
// check to see if the upcoming number is really an IPv4
// address. If it is, convert it to 2 ushort numbers
//
for (int j = i; (address[j] != ']') &&
(address[j] != ':') &&
(address[j] != '%') &&
(address[j] != '/') &&
(j < i + 4); ++j) {
if (address[j] == '.') {
//
// we have an IPv4 address. Find the end of it:
// we know that since we have a valid IPv6
// address, the only things that will terminate
// the IPv4 address are the prefix delimiter '/'
// or the end-of-string (which we conveniently
// delimited with ']')
//
while ((address[j] != ']') && (address[j] != '/') && (address[j] != '%')) {
++j;
}
number = IPv4AddressHelper.ParseHostNumber(address, i, j);
ValidateIndex(index);
numbers[index++] = (ushort)(number>>16);
ValidateIndex(index);
numbers[index++] = (ushort)number;
i = j;
//
// set this to avoid adding another number to
// the array if there's a prefix
//
number = 0;
numberIsValid = false;
break;
}
}
break;
case '/':
if (numberIsValid) {
numbers[index++] = (ushort)number;
numberIsValid = false;
}
//
// since we have a valid IPv6 address string, the prefix
// length is the last token in the string
//
for (++i; address[i] != ']'; ++i) {
PrefixLength = PrefixLength * 10 + (address[i] - '0');
}
break;
default:
number = number * 16 + Uri.FromHex(address[i++]);
break;
}
}
//
// add number to the array if its not the prefix length or part of
// an IPv4 address that's already been handled
//
if (numberIsValid) {
ValidateIndex(index);
numbers[index++] = (ushort)number;
}
//
// if we had a compressor sequence ("::") then we need to expand the
// numbers array
//
if (compressorIndex > 0) {
int toIndex = NumberOfLabels - 1;
int fromIndex = index - 1;
for (int i = index - compressorIndex; i > 0 ; --i) {
ValidateIndex(fromIndex);
ValidateIndex(toIndex);
numbers[toIndex--] = numbers[fromIndex];
ValidateIndex(fromIndex);
numbers[fromIndex--] = 0;
}
}
//
// is the address loopback? Loopback is defined as one of:
//
// 0:0:0:0:0:0:0:1
// 0:0:0:0:0:0:127.0.0.1 == 0:0:0:0:0:0:7F00:0001
// 0:0:0:0:0:FFFF:127.0.0.1 == 0:0:0:0:0:FFFF:7F00:0001
//
return ((numbers[0] == 0)
&& (numbers[1] == 0)
&& (numbers[2] == 0)
&& (numbers[3] == 0)
&& (numbers[4] == 0))
&& (((numbers[5] == 0)
&& (numbers[6] == 0)
&& (numbers[7] == 1))
|| (((numbers[6] == 0x7F00)
&& (numbers[7] == 0x0001))
&& ((numbers[5] == 0)
|| (numbers[5] == 0xFFFF))));
}
[Conditional("DEBUG")]
private static void ValidateIndex(int index) {
int limit = ServicePointManager.UseStrictIPv6AddressParsing ? NumberOfLabels : NumberOfLabels + 1;
Debug.Assert(index >= 0 && index < limit, "index = " + index.ToString());
}
}
}
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