#55 add IIS rewrite map support with tests

src/Microsoft.AspNetCore.Rewrite/IISUrlRewriteOptionsExtensions.cs

@@ -66,4 +66,4 @@ public static RewriteOptions AddIISUrlRewrite(this RewriteOptions options, TextR
             return options;
         }
     }
-}
+}

src/Microsoft.AspNetCore.Rewrite/Internal/IISUrlRewrite/IISRewriteMap.cs

@@ -0,0 +1,45 @@
+// 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;
+
+namespace Microsoft.AspNetCore.Rewrite.Internal.IISUrlRewrite
+{
+    public class IISRewriteMap
+    {
+        private readonly Dictionary<string, string> _map = new Dictionary<string, string>();
+
+        public IISRewriteMap(string name)
+        {
+            if (string.IsNullOrEmpty(name))
+            {
+                throw new ArgumentException(nameof(name));
+            }
+            Name = name;
+        }
+
+        public string Name { get; }
+
+        public string this[string key]
+        {
+            get
+            {
+                string value;
+                return _map.TryGetValue(key, out value) ? value : null;
+            }
+            set
+            {
+                if (string.IsNullOrEmpty(key))
+                {
+                    throw new ArgumentException(nameof(key));
+                }
+                if (string.IsNullOrEmpty(value))
+                {
+                    throw new ArgumentException(nameof(value));
+                }
+                _map[key] = value;
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/Internal/IISUrlRewrite/IISRewriteMapCollection.cs

@@ -0,0 +1,42 @@
+// 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;
+using System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.Rewrite.Internal.IISUrlRewrite
+{
+    public class IISRewriteMapCollection : IEnumerable<IISRewriteMap>
+    {
+        private readonly Dictionary<string, IISRewriteMap> _rewriteMaps = new Dictionary<string, IISRewriteMap>();
+
+        public void Add(IISRewriteMap rewriteMap)
+        {
+            if (rewriteMap != null)
+            {
+                _rewriteMaps[rewriteMap.Name] = rewriteMap;
+            }
+        }
+
+        public int Count => _rewriteMaps.Count;
+
+        public IISRewriteMap this[string key]
+        {
+            get
+            {
+                IISRewriteMap value;
+                return _rewriteMaps.TryGetValue(key, out value) ? value : null;
+            }
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return _rewriteMaps.Values.GetEnumerator();
+        }
+
+        public IEnumerator<IISRewriteMap> GetEnumerator()
+        {
+            return _rewriteMaps.Values.GetEnumerator();
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/Internal/IISUrlRewrite/InputParser.cs

@@ -12,6 +12,16 @@ public class InputParser
         private const char Colon = ':';
         private const char OpenBrace = '{';
         private const char CloseBrace = '}';
+        private readonly IISRewriteMapCollection _rewriteMaps;
+
+        public InputParser()
+        {
+        }
+
+        public InputParser(IISRewriteMapCollection rewriteMaps)
+        {
+            _rewriteMaps = rewriteMaps;
+        }
 
         /// <summary>
         /// Creates a pattern, which is a template to create a new test string to
@@ -31,7 +41,7 @@ public Pattern ParseInputString(string testString, bool global)
             return ParseString(context, global);
         }
 
-        private static Pattern ParseString(ParserContext context, bool global)
+        private Pattern ParseString(ParserContext context, bool global)
         {
             var results = new List<PatternSegment>();
             while (context.Next())
@@ -60,7 +70,7 @@ private static Pattern ParseString(ParserContext context, bool global)
             return new Pattern(results);
         }
 
-        private static void ParseParameter(ParserContext context, IList<PatternSegment> results, bool global)
+        private void ParseParameter(ParserContext context, IList<PatternSegment> results, bool global)
         {
             context.Mark();
             // Four main cases:
@@ -128,6 +138,13 @@ private static void ParseParameter(ParserContext context, IList<PatternSegment>
                                 return;
                             }
                         default:
+                            var rewriteMap = _rewriteMaps?[parameter];
+                            if (rewriteMap != null)
+                            {
+                                var pattern = ParseString(context, global);
+                                results.Add(new RewriteMapSegment(rewriteMap, pattern));
+                                return;
+                            }
                             throw new FormatException(Resources.FormatError_InputParserUnrecognizedParameter(parameter, context.Index));
                     }
                 }

src/Microsoft.AspNetCore.Rewrite/Internal/IISUrlRewrite/RewriteMapParser.cs

@@ -0,0 +1,39 @@
+// 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.Linq;
+using System.Xml.Linq;
+
+namespace Microsoft.AspNetCore.Rewrite.Internal.IISUrlRewrite
+{
+    public static class RewriteMapParser
+    {
+        public static IISRewriteMapCollection Parse(XElement xmlRoot)
+        {
+            if (xmlRoot == null)
+            {
+                throw new ArgumentNullException(nameof(xmlRoot));
+            }
+
+            var mapsElement = xmlRoot.Descendants(RewriteTags.RewriteMaps).SingleOrDefault();
+            if (mapsElement == null)
+            {
+                return null;
+            }
+
+            var rewriteMaps = new IISRewriteMapCollection();
+            foreach (var mapElement in mapsElement.Elements(RewriteTags.RewriteMap))
+            {
+                var map = new IISRewriteMap(mapElement.Attribute(RewriteTags.Name)?.Value);
+                foreach (var addElement in mapElement.Elements(RewriteTags.Add))
+                {
+                    map[addElement.Attribute(RewriteTags.Key).Value.ToLowerInvariant()] = addElement.Attribute(RewriteTags.Value).Value;
+                }
+                rewriteMaps.Add(map);
+            }
+
+            return rewriteMaps;
+        }
+    }
+}

src/Microsoft.AspNetCore.Rewrite/Internal/IISUrlRewrite/RewriteTags.cs

@@ -13,6 +13,7 @@ public static class RewriteTags
         public const string GlobalRules = "globalRules";
         public const string IgnoreCase = "ignoreCase";
         public const string Input = "input";
+        public const string Key = "key";
         public const string LogicalGrouping = "logicalGrouping";
         public const string LogRewrittenUrl = "logRewrittenUrl";
         public const string Match = "match";
@@ -22,13 +23,16 @@ public static class RewriteTags
         public const string Negate = "negate";
         public const string Pattern = "pattern";
         public const string PatternSyntax = "patternSyntax";
-        public const string Rewrite = "rewrite";
         public const string RedirectType = "redirectType";
+        public const string Rewrite = "rewrite";
+        public const string RewriteMap = "rewriteMap";
+        public const string RewriteMaps = "rewriteMaps";
         public const string Rule = "rule";
         public const string Rules = "rules";
         public const string StopProcessing = "stopProcessing";
         public const string TrackAllCaptures = "trackAllCaptures";
         public const string Type = "type";
         public const string Url = "url";
+        public const string Value = "value";
     }
 }

src/Microsoft.AspNetCore.Rewrite/Internal/IISUrlRewrite/UrlRewriteFileParser.cs

@@ -12,21 +12,28 @@ namespace Microsoft.AspNetCore.Rewrite.Internal.IISUrlRewrite
 {
     public class UrlRewriteFileParser
     {
-        private readonly InputParser _inputParser = new InputParser();
+        private InputParser _inputParser;
 
+        /// <summary>
+        /// Parse an IIS rewrite section into a list of <see cref="IISUrlRewriteRule"/>s.
+        /// </summary>
+        /// <param name="reader">The reader containing the rewrite XML</param>
         public IList<IISUrlRewriteRule> Parse(TextReader reader)
         {
             var xmlDoc = XDocument.Load(reader, LoadOptions.SetLineInfo);
             var xmlRoot = xmlDoc.Descendants(RewriteTags.Rewrite).FirstOrDefault();
 
-            if (xmlRoot != null)
+            if (xmlRoot == null)
             {
-                var result = new List<IISUrlRewriteRule>();
-                ParseRules(xmlRoot.Descendants(RewriteTags.GlobalRules).FirstOrDefault(), result, global: true);
-                ParseRules(xmlRoot.Descendants(RewriteTags.Rules).FirstOrDefault(), result, global: false);
-                return result;
+                return null;
             }
-            return null;
+
+            _inputParser = new InputParser(RewriteMapParser.Parse(xmlRoot));
+
+            var result = new List<IISUrlRewriteRule>();
+            ParseRules(xmlRoot.Descendants(RewriteTags.GlobalRules).FirstOrDefault(), result, global: true);
+            ParseRules(xmlRoot.Descendants(RewriteTags.Rules).FirstOrDefault(), result, global: false);
+            return result;
         }
 
         private void ParseRules(XElement rules, IList<IISUrlRewriteRule> result, bool global)

src/Microsoft.AspNetCore.Rewrite/Internal/PatternSegments/RewriteMapSegment.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 Microsoft.AspNetCore.Rewrite.Internal.IISUrlRewrite;
+
+namespace Microsoft.AspNetCore.Rewrite.Internal.PatternSegments
+{
+    public class RewriteMapSegment : PatternSegment
+    {
+        private readonly IISRewriteMap _rewriteMap;
+        private readonly Pattern _pattern;
+
+        public RewriteMapSegment(IISRewriteMap rewriteMap, Pattern pattern)
+        {
+            _rewriteMap = rewriteMap;
+            _pattern = pattern;
+        }
+
+        public override string Evaluate(RewriteContext context, BackReferenceCollection ruleBackReferences, BackReferenceCollection conditionBackReferences)
+        {
+            var key = _pattern.Evaluate(context, ruleBackReferences, conditionBackReferences).ToLowerInvariant();
+            return _rewriteMap[key];
+        }
+    }
+}

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

@@ -2,10 +2,13 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Linq;
 using System.Text.RegularExpressions;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Rewrite.Internal;
 using Microsoft.AspNetCore.Rewrite.Internal.IISUrlRewrite;
+using Microsoft.AspNetCore.Rewrite.Internal.PatternSegments;
+using Microsoft.Extensions.Logging.Testing;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Rewrite.Tests.UrlRewrite
@@ -88,11 +91,48 @@ public void FormatExceptionsOnBadSyntax(string testString)
             Assert.Throws<FormatException>(() => new InputParser().ParseInputString(testString, global: false));
         }
 
-        private RewriteContext CreateTestRewriteContext()
+        [Fact]
+        public void Should_throw_FormatException_if_no_rewrite_maps_are_defined()
+        {
+            Assert.Throws<FormatException>(() => new InputParser(null).ParseInputString("{apiMap:{R:1}}", global: false));
+        }
+
+        [Fact]
+        public void Should_throw_FormatException_if_rewrite_map_not_found()
         {
+            const string definedMapName = "testMap";
+            const string undefinedMapName = "apiMap";
+            var map = new IISRewriteMap(definedMapName);
+            var maps = new IISRewriteMapCollection { map };
+            Assert.Throws<FormatException>(() => new InputParser(maps).ParseInputString($"{{{undefinedMapName}:{{R:1}}}}", global: false));
+        }
+
+        [Fact]
+        public void Should_parse_RewriteMapSegment_and_successfully_evaluate_result()
+        {
+            const string expectedMapName = "apiMap";
+            const string expectedKey = "api.test.com";
+            const string expectedValue = "test.com/api";
+            var map = new IISRewriteMap(expectedMapName);
+            map[expectedKey] = expectedValue;
+            var maps = new IISRewriteMapCollection { map };
+
+            var inputString = $"{{{expectedMapName}:{{R:1}}}}";
+            var pattern = new InputParser(maps).ParseInputString(inputString, global: false);
+            Assert.Equal(1, pattern.PatternSegments.Count);
 
+            var segment = pattern.PatternSegments.Single();
+            var rewriteMapSegment = segment as RewriteMapSegment;
+            Assert.NotNull(rewriteMapSegment);
+
+            var result = rewriteMapSegment.Evaluate(CreateTestRewriteContext(), CreateRewriteMapRuleMatch(expectedKey).BackReferences, CreateRewriteMapConditionMatch(inputString).BackReferences);
+            Assert.Equal(expectedValue, result);
+        }
+
+        private RewriteContext CreateTestRewriteContext()
+        {
             var context = new DefaultHttpContext();
-            return new RewriteContext { HttpContext = context, StaticFileProvider = null };
+            return new RewriteContext { HttpContext = context, StaticFileProvider = null, Logger = new NullLogger() };
         }
 
         private BackReferenceCollection CreateTestRuleBackReferences()
@@ -106,5 +146,17 @@ private BackReferenceCollection CreateTestCondBackReferences()
             var match = Regex.Match("foo/bar/baz", "(.*)/(.*)/(.*)");
             return new BackReferenceCollection(match.Groups);
         }
+
+        private MatchResults CreateRewriteMapRuleMatch(string input)
+        {
+            var match = Regex.Match(input, "([^/]*)/?(.*)");
+            return new MatchResults { BackReferences = new BackReferenceCollection(match.Groups), Success = match.Success };
+        }
+
+        private MatchResults CreateRewriteMapConditionMatch(string input)
+        {
+            var match = Regex.Match(input, "(.+)");
+            return new MatchResults { BackReferences = new BackReferenceCollection(match.Groups), Success = match.Success };
+        }
     }
 }