IIS UrlRewrite parsing.

BasicMiddleware.sln

@@ -13,6 +13,7 @@ EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{99B72A07-32D6-434D-B44D-D064E3C13E08}"
 	ProjectSection(SolutionItems) = preProject
 		global.json = global.json
+		NuGetPackageVerifier.json = NuGetPackageVerifier.json
 	EndProjectSection
 EndProject
 Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNetCore.Buffering", "src\Microsoft.AspNetCore.Buffering\Microsoft.AspNetCore.Buffering.xproj", "{2363D0DD-A3BF-437E-9B64-B33AE132D875}"

NuGetPackageVerifier.json

@@ -5,7 +5,8 @@
         ],
         "packages": {
             "Microsoft.AspNetCore.Buffering": { },
-            "Microsoft.AspNetCore.HttpOverrides": { }
+            "Microsoft.AspNetCore.HttpOverrides": { },
+            "Microsoft.AspNetCore.Rewrite": { }
         }
     },
     "Default": { // Rules to run for packages not listed in any other set.

samples/RewriteSample/Rewrite.txt

@@ -1,5 +1,4 @@
 # Ensure Https
-RewriteCond %{REQUEST_URI} ^foo/  
 RewriteCond %{HTTPS} off   
 # U is a new flag to represent full URL rewrites
 RewriteRule ^(.*)$ https://www.example.com$1 [L,U]

samples/RewriteSample/Startup.cs

@@ -7,11 +7,13 @@ namespace RewriteSample
 {
     public class Startup
     {
-        public void Configure(IApplicationBuilder app)
-        { 
+        public void Configure(IApplicationBuilder app, IHostingEnvironment hostingEnv)
+        {
             app.UseRewriter(new UrlRewriteOptions()
-                .ImportFromModRewrite("Rewrite.txt"));
+                  .ImportFromUrlRewrite(hostingEnv, "UrlRewrite.xml")
+                  .ImportFromModRewrite(hostingEnv, "Rewrite.txt"));
             app.Run(context => context.Response.WriteAsync(context.Request.Path));
+
         }
 
         public static void Main(string[] args)

samples/RewriteSample/UrlRewrite.xml

@@ -0,0 +1,19 @@
+<rewrite>
+  <rules>
+    <rule name="Fail bad requests">
+      <match url=".*"/>
+      <conditions>
+        <add input="{HTTP_HOST}" pattern="localhost" negate="true" />
+      </conditions>
+      <action type="AbortRequest" />
+    </rule>
+    <rule name="Redirect from blog">
+      <match url="^blog/([_0-9a-z-]+)/([0-9]+)" />
+      <action type="Redirect" url="article/{R:2}/{R:1}" redirectType="Found" />
+    </rule>
+    <rule name="Rewrite to article.aspx">
+      <match url="^article/([0-9]+)/([_0-9a-z-]+)" />
+      <action type="Rewrite" url="article.aspx?id={R:1}&amp;title={R:2}" />
+    </rule>
+  </rules>
+</rewrite>

src/Microsoft.AspNetCore.Rewrite/ModRewrite/ModRewriteExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.IO;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Rewrite.ModRewrite;
 
 namespace Microsoft.AspNetCore.Rewrite
@@ -13,17 +14,27 @@ namespace Microsoft.AspNetCore.Rewrite
         /// Imports rules from a mod_rewrite file and adds the rules to current rules. 
         /// </summary>
         /// <param name="options">The UrlRewrite options.</param>
+        /// <param name="hostingEnv"></param>
         /// <param name="filePath">The path to the file containing mod_rewrite rules.</param>
-        public static UrlRewriteOptions ImportFromModRewrite(this UrlRewriteOptions options, string filePath)
+        public static UrlRewriteOptions ImportFromModRewrite(this UrlRewriteOptions options, IHostingEnvironment hostingEnv, string filePath)
         {
-            // TODO use IHostingEnvironment as param.
+            if (options == null)
+            {
+                throw new ArgumentNullException("UrlRewriteOptions is null");
+            }
+
+            if (hostingEnv == null)
+            {
+                throw new ArgumentNullException("HostingEnvironment is null");
+            }
+
             if (string.IsNullOrEmpty(filePath))
             {
                 throw new ArgumentException(nameof(filePath));
             }
-            // TODO IHosting to fix!
 
-            using (var stream = File.OpenRead(filePath))
+            var path = Path.Combine(hostingEnv.ContentRootPath, filePath);
+            using (var stream = File.OpenRead(path))
             {
                 options.Rules.AddRange(FileParser.Parse(new StreamReader(stream)));
             };

src/Microsoft.AspNetCore.Rewrite/ModRewrite/Pattern.cs

@@ -8,7 +8,7 @@ using System.Text.RegularExpressions;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Rewrite.ModRewrite;
 
-namespace Microsoft.AspNetCore.Rewrite
+namespace Microsoft.AspNetCore.Rewrite.ModRewrite
 {
     /// <summary>
     /// Contains a sequence of pattern segments, which on obtaining the context, will create the appropriate

src/Microsoft.AspNetCore.Rewrite/ModRewrite/PatternSegment.cs

@@ -1,7 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore.Rewrite
+namespace Microsoft.AspNetCore.Rewrite.ModRewrite
 {
     /// <summary>
     /// A Pattern segment contains a portion of the test string/ substitution segment with a type associated.

src/Microsoft.AspNetCore.Rewrite/Operands/IntegerOperand.cs

@@ -25,6 +25,7 @@ namespace Microsoft.AspNetCore.Rewrite.Operands
             {
                 throw new FormatException("Syntax error for integers in comparison.");
             }
+            Value = compValue;
             Operation = operation;
         }
 

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/ActionType.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public enum ActionType
+    {
+        None,
+        Rewrite,
+        Redirect,
+        CustomResponse,
+        AbortRequest
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/Condition.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public class Condition
+    {
+        public Pattern Input { get; set; } 
+        public Regex MatchPattern { get; set; }
+        public bool Negate { get; set; }
+        public bool IgnoreCase { get; set; } = true;
+        public MatchType MatchType { get; set; } = MatchType.Pattern;
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/Conditions.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public class Conditions
+    {
+        public List<Condition> ConditionList { get; set; } = new List<Condition>();
+        public LogicalGrouping MatchType { get; set; } // default is MatchAll
+        public bool TrackingAllCaptures { get; set; } 
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/InitialMatch.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public class InitialMatch
+    {
+        public Regex Url { get; set; } // TODO must be a non-empty string, throw in check after parsing?
+        public bool IgnoreCase { get; set; } = true;
+        public bool Negate { get; set; }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/InputParser.cs

@@ -0,0 +1,197 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Rewrite.Internal;
+using Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    /// <summary>
+    /// </summary>
+    public class InputParser
+    {
+        private const char Colon = ':';
+        private const char OpenBrace = '{';
+        private const char CloseBrace = '}';
+
+        /// <summary>
+        /// Creates a pattern, which is a template to create a new test string to 
+        /// compare to the condition. Can contain server variables, back references, etc.
+        /// </summary>
+        /// <param name="testString"></param>
+        /// <returns>A new <see cref="Pattern"/>, containing a list of <see cref="PatternSegment"/></returns>
+        public static Pattern ParseInputString(string testString)
+        {
+            if (testString == null)
+            {
+                testString = string.Empty;
+            }
+
+            var context = new ParserContext(testString);
+            return ParseString(context);
+        }
+
+        private static Pattern ParseString(ParserContext context)
+        {
+            var results = new List<PatternSegment>();
+            while (context.Next())
+            {
+                if (context.Current == OpenBrace)
+                {
+                    // This is a server parameter, parse for a condition variable
+                    if (!context.Next())
+                    {
+                        throw new FormatException(context.Error());
+                    }
+                    ParseParameter(context, results);
+                }
+                else if (context.Current == CloseBrace)
+                {
+                    // TODO we should be throwing a syntax error if we have uneven close braces
+                    // Can fix by keeping track of the number of '{' and '}' with an int, where {
+                    // increments and } decrements. Throw if < 0.
+                    return new Pattern(results);
+                }
+                else
+                {
+                    // Parse for literals, which will return on either the end of the test string 
+                    // or when it hits a special character
+                    ParseLiteral(context, results);
+                }
+            }
+            return new Pattern(results);
+        }
+
+        private static void ParseParameter(ParserContext context, List<PatternSegment> results)
+        {
+            context.Mark();
+            // Four main cases:
+            // 1. {NAME} - Server Variable, create lambda to get the part of the context
+            // 2. {R:1}  - Rule parameter
+            // 3. {C:1}  - Condition Parameter
+            // 4. {function:xxx} - String function 
+            // TODO consider perf here. This is on startup and will only happen one time
+            // (unless we support Reload)
+            string parameter;
+            while (context.Next())
+            {
+                if (context.Current == CloseBrace)
+                {
+                    // This is just a server variable, so we do a lookup and verify the server variable exists.
+                    parameter = context.Capture();
+                    results.Add(ServerVariables.FindServerVariable(parameter));
+                    return;
+                }
+                else if (context.Current == Colon)
+                {
+                    parameter = context.Capture();
+                    
+                    // Only 5 strings to expect here. Case sensitive.
+                    switch (parameter)
+                    {
+                        case "ToLower":
+                            {
+                                var pattern = ParseString(context);
+                                results.Add(new ToLowerSegment(pattern));
+
+                                // at this point, we expect our context to be on the ending closing brace,
+                                // because the ParseString() call will increment the context until it 
+                                // has processed the new string.
+                                if (context.Current != CloseBrace)
+                                {
+                                    throw new FormatException("Lacking close brace for parameter at index: " + context.GetIndex());
+                                }
+                            }
+                            break;
+                        case "UrlDecode":
+                            {
+                                throw new NotImplementedException("UrlDecode is not supported.");
+                            }
+                        case "UrlEncode":
+                            {
+                                var pattern = ParseString(context);
+                                results.Add(new UrlEncodeSegment(pattern));
+
+                                if (context.Current != CloseBrace)
+                                {
+                                    throw new FormatException("Lacking close brace for parameter at index: " + context.GetIndex());
+                                }
+                            }
+                            break;
+                        case "R":
+                            {
+                                var index = GetBackReferenceIndex(context);
+                                results.Add(new RuleMatchSegment(index));
+                                return;
+                            }
+                        case "C":
+                            {
+                                var index = GetBackReferenceIndex(context);
+                                results.Add(new ConditionMatchSegment(index));
+                                return;
+                            }
+                        default:
+                            throw new FormatException("Unrecognized parameter type: " + parameter + ", terminated at index: " + context.GetIndex());
+                    }
+                }
+            }
+        }
+
+        private static int GetBackReferenceIndex(ParserContext context)
+        {
+            if (!context.Next())
+            {
+                throw new FormatException("No index avaible for backreference at index: " + context.GetIndex());
+            }
+
+            context.Mark();
+            while (context.Current != CloseBrace)
+            {
+                if (!context.Next())
+                {
+                    throw new FormatException("Lacking close brace for parameter at index: " + context.GetIndex());
+                }
+            }
+
+            var res = context.Capture();
+            int index;
+            if (!int.TryParse(res, out index))
+            {
+                throw new FormatException("Syntax error, invalid integer in response parameter at index: " + context.GetIndex());
+            }
+
+            if (index > 9 || index < 0)
+            {
+                throw new FormatException("Invalid integer into backreference " + index + "at index: " + context.GetIndex());
+            }
+            return index;
+        }
+
+        private static bool ParseLiteral(ParserContext context, List<PatternSegment> results)
+        {
+            context.Mark();
+            string literal;
+            while (true)
+            {
+                if (context.Current == OpenBrace || context.Current == CloseBrace)
+                {
+                    literal = context.Capture();
+                    context.Back();
+                    break;
+                }
+
+                if (!context.Next())
+                {
+                    literal = context.Capture();
+                    break;
+                }
+            }
+
+            results.Add(new LiteralSegment(literal));
+            return true;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/LogicalGrouping.cs

@@ -0,0 +1,11 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public enum LogicalGrouping
+    {
+        MatchAll,
+        MatchAny
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/MatchType.cs

@@ -0,0 +1,12 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public enum MatchType
+    {
+        Pattern,
+        IsFile,
+        IsDirectory
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/Pattern.cs

@@ -0,0 +1,30 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Text;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public class Pattern
+    {
+        public IList<PatternSegment> PatternSegments { get; }
+
+        public Pattern(List<PatternSegment> patternSegments)
+        {
+            PatternSegments = patternSegments;
+        }
+
+        public string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            var strBuilder = new StringBuilder();
+            foreach (var pattern in PatternSegments)
+            {
+                strBuilder.Append(pattern.Evaluate(context, ruleMatch, condMatch));
+            }
+            return strBuilder.ToString();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegment.cs

@@ -0,0 +1,15 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public abstract class PatternSegment
+    {
+        //                                                 Match from prevRule, Match from prevCond
+        public abstract string Evaluate(HttpContext context, Match ruleMatch, Match condMatch);
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/ConditionMatchSegment.cs

@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class ConditionMatchSegment : PatternSegment
+    {
+        public int Index { get; set; }
+
+        public ConditionMatchSegment(int index)
+        {
+            Index = index;
+        }
+
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return condMatch?.Groups[Index]?.Value;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/HeaderSegment.cs

@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class HeaderSegment : PatternSegment
+    {
+        public string Header { get; set; }
+        
+        public HeaderSegment(string header)
+        {
+            Header = header;
+        }
+
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Request.Headers[Header];
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/IsHttpsSegment.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class IsHttpsSegment : PatternSegment
+    {
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Request.IsHttps ? "ON" : "OFF";
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/LiteralSegment.cs

@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class LiteralSegment : PatternSegment
+    {
+        public string Literal { get; set; }
+
+        public LiteralSegment(string literal)
+        {
+            Literal = literal;
+        }
+
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return Literal;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/LocalAddressSegment.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class LocalAddressSegment : PatternSegment
+    {
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Connection.LocalIpAddress?.ToString();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/QueryStringSegment.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class QueryStringSegment : PatternSegment
+    {
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Request.QueryString.ToString();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/RemoteAddressSegment.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class RemoteAddressSegment : PatternSegment
+    {
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Connection.RemoteIpAddress?.ToString();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/RemotePortSegment.cs

@@ -0,0 +1,17 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Globalization;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class RemotePortSegment : PatternSegment
+    {
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Connection.RemotePort.ToString(CultureInfo.InvariantCulture);
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/RuleMatchSegment.cs

@@ -0,0 +1,23 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class RuleMatchSegment : PatternSegment
+    {
+        public int Index { get; set; }
+
+        public RuleMatchSegment(int index)
+        {
+            Index = index;
+        }
+
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return ruleMatch?.Groups[Index]?.Value;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/ToLowerSegment.cs

@@ -0,0 +1,24 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class ToLowerSegment : PatternSegment
+    {
+        public Pattern Pattern { get; set; }
+
+        public ToLowerSegment(Pattern pattern)
+        {
+            Pattern = pattern;
+        }
+
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            var pattern = Pattern.Evaluate(context, ruleMatch, condMatch);
+            return pattern.ToLowerInvariant();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/UrlEncodeSegment.cs

@@ -0,0 +1,25 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.Encodings.Web;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class UrlEncodeSegment : PatternSegment
+    {
+        public Pattern Pattern { get; set; }
+        
+        public UrlEncodeSegment(Pattern pattern)
+        {
+            Pattern = pattern;
+        }
+
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            var pattern = Pattern.Evaluate(context, ruleMatch, condMatch);
+            return UrlEncoder.Default.Encode(pattern);
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSegments/UrlSegment.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments
+{
+    public class UrlSegment : PatternSegment
+    {
+        public override string Evaluate(HttpContext context, Match ruleMatch, Match condMatch)
+        {
+            return context.Request.Path.ToString();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/PatternSyntax.cs

@@ -0,0 +1,12 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public enum PatternSyntax
+    {
+        ECMAScript,
+        WildCard,
+        ExactMatch
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/RedirectType.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public enum RedirectType
+    {
+        Permanent = 301,
+        Found = 302,
+        SeeOther = 303,
+        Temporary = 307
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/RewriteTags.cs

@@ -0,0 +1,34 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public static class RewriteTags
+    {
+        // TODO More strings to be added later once further implementations are added.
+        public const string Rewrite = "rewrite";
+        public const string GlobalRules = "globalRules";
+        public const string Rules = "rules";
+        public const string Rule = "rule";
+        public const string Action = "action";
+        public const string Name = "name";
+        public const string Enabled = "enabled";
+        public const string PatternSyntax = "patternSyntax";
+        public const string StopProcessing = "stopProcessing";
+        public const string Match = "match";
+        public const string Conditions = "conditions";
+        public const string IgnoreCase = "ignoreCase";
+        public const string Negate = "negate";
+        public const string Url = "url";
+        public const string MatchType = "matchType";
+        public const string Add = "add";
+        public const string TrackingAllCaptures = "trackingAllCaptures";
+        public const string MatchPattern = "matchPattern";
+        public const string Input = "input";
+        public const string Pattern = "pattern";
+        public const string Type = "type";
+        public const string AppendQuery = "appendQuery";
+        public const string LogRewrittenUrl = "logRewrittenUrl";
+        public const string RedirectType = "redirectType";
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/ServerVariables.cs

@@ -0,0 +1,61 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Globalization;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Rewrite.UrlRewrite.PatternSegments;
+using Microsoft.Net.Http.Headers;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public static class ServerVariables
+    { 
+        public static PatternSegment FindServerVariable(string serverVariable)
+        {
+            switch(serverVariable)
+            {
+                // TODO Add all server variables here.
+                case "ALL_RAW":
+                    throw new NotImplementedException();
+                case "APP_POOL_ID":
+                    throw new NotImplementedException();
+                case "CONTENT_LENGTH":
+                    return new HeaderSegment(HeaderNames.ContentLength);
+                case "CONTENT_TYPE":
+                    return new HeaderSegment(HeaderNames.ContentType);
+                case "HTTP_ACCEPT":
+                    return new HeaderSegment(HeaderNames.Accept);
+                case "HTTP_COOKIE":
+                    return new HeaderSegment(HeaderNames.Cookie);
+                case "HTTP_HOST":
+                    return new HeaderSegment(HeaderNames.Host);
+                case "HTTP_PROXY_CONNECTION":
+                    return new HeaderSegment(HeaderNames.ProxyAuthenticate);
+                case "HTTP_REFERER":
+                    return new HeaderSegment(HeaderNames.Referer);
+                case "HTTP_USER_AGENT":
+                    return new HeaderSegment(HeaderNames.UserAgent);
+                case "HTTP_CONNECTION":
+                    return new HeaderSegment(HeaderNames.Connection);
+                case "HTTP_URL":
+                    return new UrlSegment();
+                case "HTTPS":
+                    return new IsHttpsSegment();
+                case "LOCAL_ADDR":
+                    return new LocalAddressSegment();
+                case "QUERY_STRING":
+                    return new QueryStringSegment();
+                case "REMOTE_ADDR":
+                    return new RemoteAddressSegment();
+                case "REMOTE_HOST":
+                    throw new NotImplementedException();
+                case "REMOTE_PORT":
+                    return new RemotePortSegment();
+                default:
+                    throw new FormatException("Unrecognized server variable.");
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/UrlAction.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public class UrlAction
+    {
+        public ActionType Type { get; set; }
+        public Pattern Url { get; set; }
+        public bool AppendQueryString { get; set; }
+        public bool LogRewrittenUrl { get; set; }
+        public RedirectType RedirectType { get; set; } = RedirectType.Permanent;
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/UrlRewriteExtensions.cs

@@ -0,0 +1,44 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.IO;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Rewrite.UrlRewrite;
+
+namespace Microsoft.AspNetCore.Rewrite
+{
+    public static class UrlRewriteExtensions
+    {
+        /// <summary>
+        /// Imports rules from a mod_rewrite file and adds the rules to current rules. 
+        /// </summary>
+        /// <param name="options">The UrlRewrite options.</param>
+        /// <param name="hostingEnv"></param>
+        /// <param name="filePath">The path to the file containing urlrewrite rules.</param>
+        public static UrlRewriteOptions ImportFromUrlRewrite(this UrlRewriteOptions options, IHostingEnvironment hostingEnv, string filePath)
+        {
+            if (options == null)
+            {
+                throw new ArgumentNullException("UrlRewriteOptions is null");
+            }
+
+            if (hostingEnv == null)
+            {
+                throw new ArgumentNullException("HostingEnvironment is null");
+            }
+
+            if (string.IsNullOrEmpty(filePath))
+            {
+                throw new ArgumentException(nameof(filePath));
+            }
+
+            var path = Path.Combine(hostingEnv.ContentRootPath, filePath);
+            using (var stream = File.OpenRead(path))
+            {
+                options.Rules.AddRange(UrlRewriteFileParser.Parse(new StreamReader(stream)));
+            };
+            return options;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/UrlRewriteFileParser.cs

@@ -0,0 +1,228 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.RegularExpressions;
+using System.Xml.Linq;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    // TODO rename 
+    public static class UrlRewriteFileParser
+    {
+        private static readonly TimeSpan RegexTimeout = TimeSpan.FromMilliseconds(1);
+        public static List<UrlRewriteRule> Parse(TextReader reader)
+        {
+            var temp = XDocument.Load(reader);
+            var xmlRoot = temp.Descendants(RewriteTags.Rewrite);
+            var rules = new List<UrlRewriteRule>();
+
+            if (xmlRoot != null)
+            {
+                // there is a valid rewrite block, go through each rule and process
+                GetGlobalRules(xmlRoot.Descendants(RewriteTags.GlobalRules), rules);
+                GetRules(xmlRoot.Descendants(RewriteTags.Rules), rules);
+            }
+            return rules;
+        }
+
+        private static void GetGlobalRules(IEnumerable<XElement> globalRules, List<UrlRewriteRule> result)
+        {
+            foreach (var rule in globalRules.Elements(RewriteTags.Rule) ?? Enumerable.Empty<XElement>())
+            {
+                var res = new UrlRewriteRule();
+                SetRuleAttributes(rule, res);
+                // TODO handle full url with global rules - may or may not support
+                res.Action = CreateUrlAction(rule.Element(RewriteTags.Action));
+                result.Add(res);
+            }
+        }
+
+        private static void GetRules(IEnumerable<XElement> rules, List<UrlRewriteRule> result)
+        {
+            // TODO Better null check?
+            foreach (var rule in rules.Elements(RewriteTags.Rule) ?? Enumerable.Empty<XElement>())
+            {
+                var res = new UrlRewriteRule();
+                SetRuleAttributes(rule, res);
+                res.Action = CreateUrlAction(rule.Element(RewriteTags.Action));
+                result.Add(res);
+            }
+        }
+
+        private static void SetRuleAttributes(XElement rule, UrlRewriteRule res)
+        {
+            if (rule == null)
+            {
+                return;
+            }
+
+            res.Name =  rule.Attribute(RewriteTags.Name)?.Value;
+
+            bool enabled;
+            if (bool.TryParse(rule.Attribute(RewriteTags.Enabled)?.Value, out enabled))
+            {
+                res.Enabled = enabled;
+            }
+
+            PatternSyntax patternSyntax;
+            if (Enum.TryParse(rule.Attribute(RewriteTags.PatternSyntax)?.Value, out patternSyntax))
+            {
+                res.PatternSyntax = patternSyntax;
+            }
+
+            bool stopProcessing;
+            if (bool.TryParse(rule.Attribute(RewriteTags.StopProcessing)?.Value, out stopProcessing))
+            {
+                res.StopProcessing = stopProcessing;
+            }
+
+            res.Match = CreateMatch(rule.Element(RewriteTags.Match));
+            res.Conditions = CreateConditions(rule.Element(RewriteTags.Conditions));
+        }
+
+        private static InitialMatch CreateMatch(XElement match)
+        {
+            if (match == null)
+            {
+                return null;
+            }
+
+            var matchRes = new InitialMatch();
+
+            bool parBool;
+            if (bool.TryParse(match.Attribute(RewriteTags.IgnoreCase)?.Value, out parBool))
+            {
+                matchRes.IgnoreCase = parBool;
+            }
+
+            if (bool.TryParse(match.Attribute(RewriteTags.Negate)?.Value, out parBool))
+            {
+                matchRes.Negate = parBool;
+            }
+
+            var parsedInputString = match.Attribute(RewriteTags.Url)?.Value;
+
+            if (matchRes.IgnoreCase)
+            {
+                matchRes.Url = new Regex(parsedInputString, RegexOptions.IgnoreCase | RegexOptions.Compiled, RegexTimeout);
+            }
+            else
+            {
+                matchRes.Url = new Regex(parsedInputString, RegexOptions.Compiled, RegexTimeout);
+            }
+            return matchRes;
+        }
+
+
+        private static Conditions CreateConditions(XElement conditions)
+        {
+            var condRes = new Conditions();
+            if (conditions == null)
+            {
+                return condRes; // TODO make sure no null exception on Conditions
+            }
+
+            LogicalGrouping grouping;
+            if (Enum.TryParse(conditions.Attribute(RewriteTags.MatchType)?.Value, out grouping))
+            {
+                condRes.MatchType = grouping;
+            }
+
+            bool parBool;
+            if (bool.TryParse(conditions.Attribute(RewriteTags.TrackingAllCaptures)?.Value, out parBool))
+            {
+                condRes.TrackingAllCaptures = parBool;
+            }
+
+            foreach (var cond in conditions.Elements(RewriteTags.Add))
+            {
+                condRes.ConditionList.Add(CreateCondition(cond));
+            }
+            return condRes;
+        }
+
+        private static Condition CreateCondition(XElement condition)
+        {
+            if (condition == null)
+            {
+                return null;
+            }
+
+            var condRes = new Condition();
+
+            bool parBool;
+            if (bool.TryParse(condition.Attribute(RewriteTags.IgnoreCase)?.Value, out parBool))
+            {
+                condRes.IgnoreCase = parBool;
+            }
+
+            if (bool.TryParse(condition.Attribute(RewriteTags.Negate)?.Value, out parBool))
+            {
+                condRes.Negate = parBool;
+            }
+
+            MatchType matchType;
+            if (Enum.TryParse(condition.Attribute(RewriteTags.MatchPattern)?.Value, out matchType))
+            {
+                condRes.MatchType = matchType;
+            }
+
+            var parsedInputString = condition.Attribute(RewriteTags.Input)?.Value;
+            if (parsedInputString != null)
+            {
+                condRes.Input = InputParser.ParseInputString(parsedInputString);
+            }
+
+            parsedInputString = condition.Attribute(RewriteTags.Pattern)?.Value;
+
+            if (condRes.IgnoreCase)
+            {
+                condRes.MatchPattern = new Regex(parsedInputString, RegexOptions.IgnoreCase | RegexOptions.Compiled, RegexTimeout);
+            }
+            else
+            {
+                condRes.MatchPattern = new Regex(parsedInputString, RegexOptions.Compiled, RegexTimeout);
+            }
+            return condRes;
+        }
+
+        private static UrlAction CreateUrlAction(XElement urlAction)
+        {
+            if (urlAction == null)
+            {
+                throw new FormatException("Action is a required element of a rule.");
+            }
+            var actionRes = new UrlAction();
+
+            ActionType actionType;
+            if (Enum.TryParse(urlAction.Attribute(RewriteTags.Type)?.Value, out actionType))
+            {
+                actionRes.Type = actionType;
+            }
+
+            bool parseBool;
+            if (bool.TryParse(urlAction.Attribute(RewriteTags.AppendQuery)?.Value, out parseBool))
+            {
+                actionRes.AppendQueryString = parseBool;
+            }
+
+            if (bool.TryParse(urlAction.Attribute(RewriteTags.LogRewrittenUrl)?.Value, out parseBool))
+            {
+                actionRes.LogRewrittenUrl = parseBool;
+            }
+
+            RedirectType redirectType;
+            if (Enum.TryParse(urlAction.Attribute(RewriteTags.RedirectType)?.Value, out redirectType))
+            {
+                actionRes.RedirectType = redirectType;
+            }
+
+            actionRes.Url = InputParser.ParseInputString(urlAction.Attribute(RewriteTags.Url)?.Value);
+            return actionRes;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/UrlRewrite/UrlRewriteRule.cs

@@ -0,0 +1,25 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.AspNetCore.Rewrite.RuleAbstraction;
+
+namespace Microsoft.AspNetCore.Rewrite.UrlRewrite
+{
+    public class UrlRewriteRule : Rule
+    {
+        public string Name { get; set; }
+        public bool Enabled { get; set; } = true;
+        public PatternSyntax PatternSyntax { get; set; }
+        public bool StopProcessing { get; set; }
+        public InitialMatch Match { get; set; }
+        public Conditions Conditions { get; set; }
+        public UrlAction Action { get; set; }
+
+        public override RuleResult ApplyRule(UrlRewriteContext context)
+        {
+            // TODO 
+            throw new NotImplementedException();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/project.json

@@ -31,6 +31,7 @@
   "frameworks": {
     "net451": {
       "frameworkAssemblies": {
+        "System.Xml": "",
         "System.Xml.Linq": ""
       }
     },

test/Microsoft.AspNetCore.Rewrite.Tests/UrlRewrite/FileParserTests.cs

@@ -0,0 +1,212 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.IO;
+using System.Text.RegularExpressions;
+using Microsoft.AspNetCore.Rewrite.UrlRewrite;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Rewrite.Tests.UrlRewrite
+{
+    public class FileParserTests
+    {
+        [Fact]
+        public void RuleParse_ParseTypicalRule()
+        {
+            // arrange
+            var xml = @"<rewrite>
+                            <rules>
+                                <rule name=""Rewrite to article.aspx"">
+                                    <match url = ""^article/([0-9]+)/([_0-9a-z-]+)"" />
+                                    <action type=""Rewrite"" url =""article.aspx?id={R:1}&amp;title={R:2}"" />
+                                </rule>
+                            </rules>
+                        </rewrite>";
+
+            var expected = new List<UrlRewriteRule>();
+            expected.Add(CreateTestRule(new List<Condition>(),
+                Url: "^article/([0-9]+)/([_0-9a-z-]+)",
+                name: "Rewrite to article.aspx",
+                actionType: ActionType.Rewrite,
+                pattern: "article.aspx?id={R:1}&amp;title={R:2}"));
+
+            // act
+            var res = UrlRewriteFileParser.Parse(new StringReader(xml));
+
+            // assert
+           AssertUrlRewriteRuleEquality(res, expected);
+        }
+
+        [Fact]
+        public void RuleParse_ParseSingleRuleWithSingleCondition()
+        {
+            // arrange
+            var xml = @"<rewrite>
+                            <rules>
+                                <rule name=""Rewrite to article.aspx"">
+                                    <match url = ""^article/([0-9]+)/([_0-9a-z-]+)"" />
+                                    <conditions>  
+                                        <add input=""{HTTPS}"" pattern=""^OFF$"" />  
+                                    </conditions>  
+                                    <action type=""Rewrite"" url =""article.aspx?id={R:1}&amp;title={R:2}"" />
+                                </rule>
+                            </rules>
+                        </rewrite>";
+
+            var condList = new List<Condition>();
+            condList.Add(new Condition
+            {
+                Input = InputParser.ParseInputString("{HTTPS}"),
+                MatchPattern = new Regex("^OFF$")
+            });
+
+            var expected = new List<UrlRewriteRule>();
+            expected.Add(CreateTestRule(condList,
+                Url: "^article/([0-9]+)/([_0-9a-z-]+)",
+                name: "Rewrite to article.aspx",
+                actionType: ActionType.Rewrite,
+                pattern: "article.aspx?id={R:1}&amp;title={R:2}"));
+
+            // act
+            var res = UrlRewriteFileParser.Parse(new StringReader(xml));
+            
+            // assert
+            AssertUrlRewriteRuleEquality(expected, res);
+        }
+
+        [Fact]
+        public void RuleParse_ParseMultipleRules()
+        {
+            // arrange
+            var xml = @"<rewrite>
+                            <rules>
+                                <rule name=""Rewrite to article.aspx"">
+                                    <match url = ""^article/([0-9]+)/([_0-9a-z-]+)"" />
+                                    <conditions>  
+                                        <add input=""{HTTPS}"" pattern=""^OFF$"" />  
+                                    </conditions>  
+                                    <action type=""Rewrite"" url =""article.aspx?id={R:1}&amp;title={R:2}"" />
+                                </rule>
+                                <rule name=""Rewrite to article.aspx"">
+                                    <match url = ""^article/([0-9]+)/([_0-9a-z-]+)"" />
+                                    <conditions>  
+                                        <add input=""{HTTPS}"" pattern=""^OFF$"" />  
+                                    </conditions>  
+                                    <action type=""Redirect"" url =""article.aspx?id={R:1}&amp;title={R:2}"" />
+                                </rule>
+                            </rules>
+                        </rewrite>";
+
+            var condList = new List<Condition>();
+            condList.Add(new Condition
+            {
+                Input = InputParser.ParseInputString("{HTTPS}"),
+                MatchPattern = new Regex("^OFF$")
+            });
+
+            var expected = new List<UrlRewriteRule>();
+            expected.Add(CreateTestRule(condList,
+                Url: "^article/([0-9]+)/([_0-9a-z-]+)",
+                name: "Rewrite to article.aspx",
+                actionType: ActionType.Rewrite,
+                pattern: "article.aspx?id={R:1}&amp;title={R:2}"));
+            expected.Add(CreateTestRule(condList,
+                Url: "^article/([0-9]+)/([_0-9a-z-]+)",
+                name: "Rewrite to article.aspx",
+                actionType: ActionType.Redirect,
+                pattern: "article.aspx?id={R:1}&amp;title={R:2}"));
+
+            // act
+            var res = UrlRewriteFileParser.Parse(new StringReader(xml));
+
+            // assert
+            AssertUrlRewriteRuleEquality(expected, res);
+        }
+
+        // Creates a rule with appropriate default values of the url rewrite rule.
+        private UrlRewriteRule CreateTestRule(List<Condition> conditions,
+            LogicalGrouping condGrouping = LogicalGrouping.MatchAll,
+            bool condTracking = false,
+            string name = "",
+            bool enabled = true,
+            PatternSyntax patternSyntax = PatternSyntax.ECMAScript,
+            bool stopProcessing = false,
+            string Url = "",
+            bool ignoreCase = true,
+            bool negate = false,
+            ActionType actionType = ActionType.None,
+            string pattern = "",
+            bool appendQueryString = false,
+            bool rewrittenUrl = false,
+            RedirectType redirectType = RedirectType.Permanent
+            )
+        {
+            return new UrlRewriteRule
+            {
+                Action = new UrlAction
+                {
+                    Url = InputParser.ParseInputString(pattern),
+                    Type = actionType,
+                    AppendQueryString = appendQueryString,
+                    LogRewrittenUrl = rewrittenUrl,
+                    RedirectType = redirectType
+                },
+                Name = name,
+                Enabled = enabled,
+                StopProcessing = stopProcessing,
+                PatternSyntax = patternSyntax,
+                Match = new InitialMatch
+                {
+                    Url = new Regex(Url),
+                    IgnoreCase = ignoreCase,
+                    Negate = negate
+                },
+                Conditions = new Conditions
+                {
+                    ConditionList = conditions,
+                    MatchType = condGrouping,
+                    TrackingAllCaptures = condTracking
+                }
+            };
+        }
+
+        private void AssertUrlRewriteRuleEquality(List<UrlRewriteRule> expected, List<UrlRewriteRule> actual)
+        {
+            Assert.Equal(expected.Count, actual.Count);
+            for (var i = 0; i < expected.Count; i++)
+            {
+                var r1 = expected[i];
+                var r2 = actual[i];
+
+                Assert.Equal(r1.Name, r2.Name);
+                Assert.Equal(r1.Enabled, r2.Enabled);
+                Assert.Equal(r1.StopProcessing, r2.StopProcessing);
+                Assert.Equal(r1.PatternSyntax, r2.PatternSyntax);
+
+                Assert.Equal(r1.Match.IgnoreCase, r2.Match.IgnoreCase);
+                Assert.Equal(r1.Match.Negate, r2.Match.Negate);
+
+                Assert.Equal(r1.Action.Type, r2.Action.Type);
+                Assert.Equal(r1.Action.AppendQueryString, r2.Action.AppendQueryString);
+                Assert.Equal(r1.Action.RedirectType, r2.Action.RedirectType);
+                Assert.Equal(r1.Action.LogRewrittenUrl, r2.Action.LogRewrittenUrl);
+
+                // TODO conditions, url pattern, initial match regex
+                Assert.Equal(r1.Conditions.MatchType, r2.Conditions.MatchType);
+                Assert.Equal(r1.Conditions.TrackingAllCaptures, r2.Conditions.TrackingAllCaptures);
+                Assert.Equal(r1.Conditions.ConditionList.Count, r2.Conditions.ConditionList.Count);
+
+                for (var j = 0; j < r1.Conditions.ConditionList.Count; j++)
+                {
+                    var c1 = r1.Conditions.ConditionList[j];
+                    var c2 = r2.Conditions.ConditionList[j];
+                    Assert.Equal(c1.IgnoreCase, c2.IgnoreCase);
+                    Assert.Equal(c1.Negate, c2.Negate);
+                    Assert.Equal(c1.MatchType, c2.MatchType);
+                    Assert.Equal(c1.Input.PatternSegments.Count, c2.Input.PatternSegments.Count);
+                }
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Rewrite.Tests/UrlRewrite/InputParserTests.cs

@@ -0,0 +1,113 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Rewrite.UrlRewrite;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Rewrite.Tests.UrlRewrite
+{
+    public class InputParserTests
+    {
+        [Fact]
+        public void InputParser_ParseLiteralString()
+        {
+            var testString = "hello/hey/what";
+            var result = InputParser.ParseInputString(testString);
+            Assert.Equal(result.PatternSegments.Count, 1);
+        }
+
+        // Tests sizes of the pattern segments. These are all anonyomus lambdas, so cant check contents.
+        [Theory]
+        [InlineData("foo/bar/{R:1}/what", 3)]
+        [InlineData("foo/{R:1}", 2)]
+        [InlineData("foo/{R:1}/{C:2}", 4)]
+        [InlineData("foo/{R:1}{C:2}", 3)]
+        [InlineData("foo/", 1)]
+        public void InputParser_ParseStringWithBackReference(string testString, int expected)
+        {
+            var result = InputParser.ParseInputString(testString);
+            Assert.Equal(result.PatternSegments.Count, expected);
+        }
+
+        // Test actual evaluation of the lambdas, verifying the correct string comes from the evalation
+        [Theory]
+        [InlineData("hey/hello/what", "hey/hello/what")]
+        [InlineData("hey/{R:1}/what", "hey/foo/what")]
+        [InlineData("hey/{R:2}/what", "hey/bar/what")]
+        [InlineData("hey/{R:3}/what", "hey/baz/what")]
+        [InlineData("hey/{C:1}/what", "hey/foo/what")]
+        [InlineData("hey/{C:2}/what", "hey/bar/what")]
+        [InlineData("hey/{C:3}/what", "hey/baz/what")]
+        [InlineData("hey/{R:1}/{C:1}", "hey/foo/foo")]
+        public void EvaluateBackReferenceRule(string testString, string expected)
+        {
+            var middle = InputParser.ParseInputString(testString);
+            var result = middle.Evaluate(CreateTestHttpContext(), CreateTestRuleMatch(), CreateTestCondMatch());
+            Assert.Equal(result, expected);
+        }
+        
+        [Theory]
+        [InlineData("hey/{ToLower:HEY}", "hey/hey")]
+        [InlineData("hey/{ToLower:{R:1}}", "hey/foo")]
+        [InlineData("hey/{ToLower:{C:1}}", "hey/foo")]
+        [InlineData("hey/{ToLower:{C:1}/what}", "hey/foo/what")]
+        [InlineData("hey/ToLower:/what", "hey/ToLower:/what")]
+        public void EvaluatToLowerRule(string testString, string expected)
+        {
+            var middle = InputParser.ParseInputString(testString);
+            var result = middle.Evaluate(CreateTestHttpContext(), CreateTestRuleMatch(), CreateTestCondMatch());
+            Assert.Equal(result, expected);
+        }
+
+        [Theory]
+        [InlineData("hey/{UrlEncode:<hey>}", "hey/%3Chey%3E")]
+        public void EvaluatUriEncodeRule(string testString, string expected)
+        {
+            var middle = InputParser.ParseInputString(testString);
+            var result = middle.Evaluate(CreateTestHttpContext(), CreateTestRuleMatch(), CreateTestCondMatch());
+            Assert.Equal(result, expected);
+        }
+
+        [Theory]
+        [InlineData("{")]
+        [InlineData("{:}")]
+        [InlineData("{R:")]
+        [InlineData("{R:1")]
+        [InlineData("{R:A}")]
+        [InlineData("{R:10}")]
+        [InlineData("{R:-1}")]
+        [InlineData("{foo:1")]
+        [InlineData("{UrlEncode:{R:}}")]
+        [InlineData("{UrlEncode:{R:1}")]
+        public void FormatExceptionsOnBadSyntax(string testString)
+        {
+            Assert.Throws<FormatException>(() => InputParser.ParseInputString(testString));
+        }
+
+        private HttpContext CreateTestHttpContext()
+        {
+
+            HttpContext context = new DefaultHttpContext();
+            // TODO add fields if necessary
+            return context;
+        }
+
+        private Match CreateTestRuleMatch()
+        {
+            var match = Regex.Match("foo/bar/baz", "(.*)/(.*)/(.*)");
+            return match;
+        }
+
+        private Match CreateTestCondMatch()
+        {
+            var match = Regex.Match("foo/bar/baz", "(.*)/(.*)/(.*)");
+            return match;
+        }
+    }
+}