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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
namespace System.Web.Util {
internal class RegexUtil {
// this method is for the regex match which accepts the pattern from developer
// since asp.net doesn't have control of the regex pattern string and it is possible
// to take more than 2 sec to match a string, give developer option to set timeout value
public static bool IsMatch(string stringToMatch, string pattern, RegexOptions regOption, int? timeoutInMillsec) {
int timeout = GetRegexTimeout(timeoutInMillsec);
if (timeout > 0 || timeoutInMillsec.HasValue) {
return Regex.IsMatch(stringToMatch, pattern, regOption, TimeSpan.FromMilliseconds((double)timeout));
} else {
return Regex.IsMatch(stringToMatch, pattern, regOption);
}
}
public static Match Match(string stringToMatch, string pattern, RegexOptions regOption, int? timeoutInMillsec) {
int timeout = GetRegexTimeout(timeoutInMillsec);
if (timeout > 0 || timeoutInMillsec.HasValue) {
return Regex.Match(stringToMatch, pattern, regOption, TimeSpan.FromMilliseconds((double)timeout));
} else {
return Regex.Match(stringToMatch, pattern, regOption);
}
}
public static Regex CreateRegex(string pattern, RegexOptions option, int? timeoutInMillsec) {
int timeout = GetRegexTimeout(timeoutInMillsec);
if (timeout > 0 || timeoutInMillsec.HasValue) {
return new Regex(pattern, option, TimeSpan.FromMilliseconds((double)timeout));
} else {
return new Regex(pattern, option);
}
}
// This method is for the regex asp.net controls the regex pattern and it should NOT take longer than 2 secs to match the string
// so no need for developer to specify a timeout value
internal static Regex CreateRegex(string pattern, RegexOptions option) {
return CreateRegex(pattern, option, null);
}
private static bool? _isRegexTimeoutSetInAppDomain;
private static bool IsRegexTimeoutSetInAppDomain {
get {
if (!_isRegexTimeoutSetInAppDomain.HasValue) {
bool timeoutSetInAppDomain = false;
try {
timeoutSetInAppDomain = AppDomain.CurrentDomain.GetData("REGEX_DEFAULT_MATCH_TIMEOUT") != null;
} catch {
}
_isRegexTimeoutSetInAppDomain = timeoutSetInAppDomain;
}
return _isRegexTimeoutSetInAppDomain.Value;
}
}
private static int GetRegexTimeout(int? timeoutInMillsec) {
int timeout = -1;
// here is the logic for using timeout in regex
// 1. if the caller sets a timeout value, then we use it(this may cause Regex throw ArgumentOutOfRangeException,
// but developer will know what they need to do when seeing the exception)
// 2. if there is global setting in AppDomain, we do nothing(leave it to Regex to handle the timeout)
// 3. if the web app targets to 4.6.1+, then we set 2 secs timeout
if (timeoutInMillsec.HasValue) {
timeout = timeoutInMillsec.Value;
} else {
if (!IsRegexTimeoutSetInAppDomain && BinaryCompatibility.Current.TargetsAtLeastFramework461) {
timeout = 2000;
}
}
return timeout;
}
}
}
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