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//------------------------------------------------------------------------------
// <copyright file="_IPv4Address.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
using System.Diagnostics;
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 IPv4AddressHelper {
internal const long Invalid = -1;
// Note: the native parser cannot handle MaxIPv4Value, only MaxIPv4Value - 1
private const long MaxIPv4Value = UInt32.MaxValue;
private const int Octal = 8;
private const int Decimal = 10;
private const int Hex = 16;
private const int NumberOfLabels = 4;
// methods
// Parse and canonicalize
internal static string ParseCanonicalName(string str, int start, int end, ref bool isLoopback) {
unsafe {
byte* numbers = stackalloc byte[NumberOfLabels];
isLoopback = Parse(str, numbers, start, end);
return numbers[0] + "." + numbers[1] + "." + numbers[2] + "." + numbers[3];
}
}
// Only called from the IPv6Helper, only parse the canonical format
internal static int ParseHostNumber(string str, int start, int end) {
unsafe {
byte* numbers = stackalloc byte[NumberOfLabels];
ParseCanonical(str, numbers, start, end);
return (numbers[0] << 24) + (numbers[1] << 16) + (numbers[2] << 8) + numbers[3];
}
}
//
// IsValid
//
// Performs IsValid on a substring. Updates the index to where we
// believe the IPv4 address ends
//
// Inputs:
// <argument> name
// string containing possible IPv4 address
//
// <argument> start
// offset in <name> to start checking for IPv4 address
//
// <argument> end
// offset in <name> of the last character we can touch in the check
//
// Outputs:
// <argument> end
// index of last character in <name> we checked
//
// <argument> allowIPv6
// enables parsing IPv4 addresses embedded in IPv6 address literals
//
// <argument> notImplicitFile
// do not consider this URI holding an implicit filename
//
// <argument> unknownScheme
// the check is made on an unknown scheme (suppress IPv4 canonicalization)
//
// Assumes:
// The address string is terminated by either
// end of the string, characters ':' '/' '\' '?'
//
//
// Returns:
// bool
//
// Throws:
// Nothing
//
//Remark: MUST NOT be used unless all input indexes are are verified and trusted.
internal unsafe static bool IsValid(char* name, int start, ref int end, bool allowIPv6, bool notImplicitFile, bool unknownScheme) {
// IPv6 can only have canonical IPv4 embedded. Unknown schemes will not attempt parsing of non-canonical IPv4 addresses.
if (allowIPv6 || unknownScheme)
{
return IsValidCanonical(name, start, ref end, allowIPv6, notImplicitFile);
}
else
{
return ParseNonCanonical(name, start, ref end, notImplicitFile) != Invalid;
}
}
//
// IsValidCanonical
//
// Checks if the substring is a valid canonical IPv4 address or an IPv4 address embedded in an IPv6 literal
// This is an attempt to parse ABNF productions from RFC3986, Section 3.2.2:
// IP-literal = "[" ( IPv6address / IPvFuture ) "]"
// IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet
// dec-octet = DIGIT ; 0-9
// / %x31-39 DIGIT ; 10-99
// / "1" 2DIGIT ; 100-199
// / "2" %x30-34 DIGIT ; 200-249
// / "25" %x30-35 ; 250-255
//
internal unsafe static bool IsValidCanonical(char* name, int start, ref int end, bool allowIPv6, bool notImplicitFile) {
int dots = 0;
int number = 0;
bool haveNumber = false;
bool firstCharIsZero = false;
while (start < end) {
char ch = name[start];
if (allowIPv6) {
// for ipv4 inside ipv6 the terminator is either ScopeId, prefix or ipv6 terminator
if (ch == ']' || ch == '/' || ch == '%') break;
}
else if (ch == '/' || ch == '\\' || (notImplicitFile && (ch == ':' || ch == '?' || ch == '#'))) {
break;
}
if (ch <= '9' && ch >= '0') {
if (!haveNumber && (ch == '0')) {
if ((start + 1 < end) && name[start + 1] == '0') {
// 00 is not allowed as a prefix.
return false;
}
firstCharIsZero = true;
}
haveNumber = true;
number = number * 10 + (name[start] - '0');
if (number > 255) {
return false;
}
} else if (ch == '.') {
if (!haveNumber || (number > 0 && firstCharIsZero)) {
// 0 is not allowed to prefix a number.
return false;
}
++dots;
haveNumber = false;
number = 0;
firstCharIsZero = false;
} else {
return false;
}
++start;
}
bool res = (dots == 3) && haveNumber;
if (res) {
end = start;
}
return res;
}
// Parse any canonical or noncanonical IPv4 formats and return a long between 0 and MaxIPv4Value.
// Return Invalid (-1) for failures.
// If the address has less than three dots, only the rightmost section is assumed to contain the combined value for
// the missing sections: 0xFF00FFFF == 0xFF.0x00.0xFF.0xFF == 0xFF.0xFFFF
internal unsafe static long ParseNonCanonical(char* name, int start, ref int end, bool notImplicitFile)
{
int numberBase = Decimal;
char ch;
long[] parts = new long[4];
long currentValue = 0;
bool atLeastOneChar = false;
// Parse one dotted section at a time
int dotCount = 0; // Limit 3
int current = start;
for (; current < end; current++)
{
ch = name[current];
currentValue = 0;
// Figure out what base this section is in
numberBase = Decimal;
if (ch == '0')
{
numberBase = Octal;
current++;
atLeastOneChar = true;
if (current < end)
{
ch = name[current];
if (ch == 'x' || ch == 'X')
{
numberBase = Hex;
current++;
atLeastOneChar = false;
}
}
}
// Parse this section
for (; current < end; current++)
{
ch = name[current];
int digitValue;
if ((numberBase == Decimal || numberBase == Hex) && '0' <= ch && ch <= '9')
{
digitValue = ch - '0';
}
else if (numberBase == Octal && '0' <= ch && ch <= '7')
{
digitValue = ch - '0';
}
else if (numberBase == Hex && 'a' <= ch && ch <= 'f')
{
digitValue = ch + 10 - 'a';
}
else if (numberBase == Hex && 'A' <= ch && ch <= 'F')
{
digitValue = ch + 10 - 'A';
}
else
{
break; // Invalid/terminator
}
currentValue = (currentValue * numberBase) + digitValue;
if (currentValue > MaxIPv4Value) // Overflow
{
return Invalid;
}
atLeastOneChar = true;
}
if (current < end && name[current] == '.')
{
if (dotCount >= 3 // Max of 3 dots and 4 segments
|| !atLeastOneChar // No empty segmets: 1...1
// Only the last segment can be more than 255 (if there are less than 3 dots)
|| currentValue > 0xFF)
{
return Invalid;
}
parts[dotCount] = currentValue;
dotCount++;
atLeastOneChar = false;
continue;
}
// We don't get here unless We find an invalid character or a terminator
break;
}
// Terminators
if (!atLeastOneChar)
{
return Invalid; // Empty trailing segment: 1.1.1.
}
else if (current >= end)
{
// end of string, allowed
}
else if ((ch = name[current]) == '/' || ch == '\\' || (notImplicitFile && (ch == ':' || ch == '?' || ch == '#')))
{
end = current;
}
else
{
// not a valid terminating character
return Invalid;
}
parts[dotCount] = currentValue;
// Parsed, reassemble and check for overflows
switch (dotCount)
{
case 0: // 0xFFFFFFFF
if (parts[0] > MaxIPv4Value)
{
return Invalid;
}
return parts[0];
case 1: // 0xFF.0xFFFFFF
if (parts[1] > 0xffffff)
{
return Invalid;
}
return (parts[0] << 24) | (parts[1] & 0xffffff);
case 2: // 0xFF.0xFF.0xFFFF
if (parts[2] > 0xffff)
{
return Invalid;
}
return (parts[0] << 24) | ((parts[1] & 0xff) << 16) | (parts[2] & 0xffff);
case 3: // 0xFF.0xFF.0xFF.0xFF
if (parts[3] > 0xff)
{
return Invalid;
}
return (parts[0] << 24) | ((parts[1] & 0xff) << 16) | ((parts[2] & 0xff) << 8) | (parts[3] & 0xff);
default:
return Invalid;
}
}
//
// Parse
//
// Convert this IPv4 address into a sequence of 4 8-bit numbers
//
unsafe private static bool Parse(string name, byte* numbers, int start, int end) {
fixed (char* ipString = name)
{
int changedEnd = end;
long result = IPv4AddressHelper.ParseNonCanonical(ipString, start, ref changedEnd, true);
// end includes ports, so changedEnd may be different from end
Debug.Assert(result != Invalid, "Failed to parse after already validated: " + name);
numbers[0] = (byte)(result >> 24);
numbers[1] = (byte)(result >> 16);
numbers[2] = (byte)(result >> 8);
numbers[3] = (byte)(result);
}
return numbers[0] == 127;
}
// Assumes:
// <Name> has been validated and contains only decimal digits in groups
// of 8-bit numbers and the characters '.'
// Address may terminate with ':' or with the end of the string
//
unsafe private static bool ParseCanonical(string name, byte* numbers, int start, int end) {
for (int i = 0; i < NumberOfLabels; ++i) {
byte b = 0;
char ch;
for (; (start < end) && (ch = name[start]) != '.' && ch != ':'; ++start) {
b = (byte)(b * 10 + (byte)(ch - '0'));
}
numbers[i] = b;
++start;
}
return numbers[0] == 127;
}
}
}
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