1 files changed, 83 insertions, 0 deletions
diff --git a/mcs/class/referencesource/System.Web/Util/RegexUtil.cs b/mcs/class/referencesource/System.Web/Util/RegexUtil.cs
new file mode 100644
index 00000000000..b856b90e0d7
--- /dev/null
+++ b/mcs/class/referencesource/System.Web/Util/RegexUtil.cs
@@ -0,0 +1,83 @@
+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;
+        }
+    }
+}