Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/Configuration/RegexWorker.cs

@@ -0,0 +1,113 @@
+//------------------------------------------------------------------------------
+// <copyright file="RegexWorker.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+/*
+ * Base class for browser capabilities object: just a read-only dictionary
+ * holder that supports Init()
+ *
+ * 
+
+
+*/
+
+using System.Web.UI;
+using System.Collections;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using System.Globalization;
+using System.Security.Permissions;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Web.RegularExpressions;
+using System.Web.Util;
+
+namespace System.Web.Configuration {
+
+    //
+    public class RegexWorker {
+        internal static readonly Regex RefPat = new BrowserCapsRefRegex();
+        private Hashtable _groups;
+        private HttpBrowserCapabilities _browserCaps;
+
+        public RegexWorker(HttpBrowserCapabilities browserCaps) {
+            _browserCaps = browserCaps;
+        }
+
+        private string Lookup(string from) {
+            MatchCollection matches = RefPat.Matches(from);
+
+            // shortcut for no reference case
+            if (matches.Count == 0) {
+                return from;
+            }
+
+            StringBuilder sb = new StringBuilder();
+            int startIndex = 0;
+
+            foreach (Match match in matches) {
+                int length = match.Index - startIndex;
+                sb.Append(from.Substring(startIndex, length));
+                startIndex = match.Index + match.Length;
+
+                string groupName = match.Groups["name"].Value;
+
+                string result = null;
+                if (_groups != null) {
+                    result = (String)_groups[groupName];
+                }
+
+                if (result == null) {
+                    result = _browserCaps[groupName];
+                }
+
+                sb.Append(result);
+            }
+
+            sb.Append(from, startIndex, from.Length - startIndex);
+            string output = sb.ToString();
+
+            // Return null instead of empty string since empty string is used to override values.
+            if (output.Length == 0) {
+                return null;
+            }
+
+            return output;
+        }
+
+        public string this[string key] {
+            get {
+                return Lookup(key);
+            }
+        }
+
+        public bool ProcessRegex(string target, string regexExpression) {
+            if(target == null) {
+                target = String.Empty;
+            }
+
+            // Adding timeout for Regex in case of malicious string causing DoS
+            Regex regex = RegexUtil.CreateRegex(regexExpression, RegexOptions.ExplicitCapture);
+            Match match = regex.Match(target);
+            if(match.Success == false) {
+                return false;
+            }
+
+            string[] groups = regex.GetGroupNames();
+
+            if (groups.Length > 0) {
+                if (_groups == null) {
+                    _groups = new Hashtable();
+                }
+
+                for (int i = 0; i < groups.Length; i++) {
+                    _groups[groups[i]] = match.Groups[i].Value;
+                }
+            }
+
+            return true;
+        }
+    }
+}