Add www to root domain redirects (#12997)

src/Middleware/Rewrite/ref/Microsoft.AspNetCore.Rewrite.netcoreapp.cs

@@ -54,6 +54,12 @@ namespace Microsoft.AspNetCore.Rewrite
         public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToHttps(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, int statusCode) { throw null; }
         public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToHttps(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, int statusCode, int? sslPort) { throw null; }
         public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToHttpsPermanent(this Microsoft.AspNetCore.Rewrite.RewriteOptions options) { throw null; }
+        public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToNonWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options) { throw null; }
+        public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToNonWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, int statusCode) { throw null; }
+        public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToNonWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, int statusCode, params string[] domains) { throw null; }
+        public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToNonWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, params string[] domains) { throw null; }
+        public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToNonWwwPermanent(this Microsoft.AspNetCore.Rewrite.RewriteOptions options) { throw null; }
+        public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToNonWwwPermanent(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, params string[] domains) { throw null; }
         public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options) { throw null; }
         public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, int statusCode) { throw null; }
         public static Microsoft.AspNetCore.Rewrite.RewriteOptions AddRedirectToWww(this Microsoft.AspNetCore.Rewrite.RewriteOptions options, int statusCode, params string[] domains) { throw null; }

src/Middleware/Rewrite/src/Extensions/RewriteMiddlewareLoggingExtensions.cs

@@ -17,6 +17,7 @@ namespace Microsoft.AspNetCore.Rewrite.Logging
         private static readonly Action<ILogger, Exception> _modRewriteMatchedRule;
         private static readonly Action<ILogger, Exception> _redirectedToHttps;
         private static readonly Action<ILogger, Exception> _redirectedToWww;
+        private static readonly Action<ILogger, Exception> _redirectedToNonWww;
         private static readonly Action<ILogger, string, Exception> _redirectedRequest;
         private static readonly Action<ILogger, string, Exception> _rewrittenRequest;
         private static readonly Action<ILogger, string, Exception> _abortedRequest;
@@ -88,6 +89,11 @@ namespace Microsoft.AspNetCore.Rewrite.Logging
                             LogLevel.Information,
                             new EventId(13, "RedirectedToWww"),
                             "Request redirected to www");
+
+            _redirectedToNonWww = LoggerMessage.Define(
+                            LogLevel.Information,
+                            new EventId(14, "RedirectedToNonWww"),
+                            "Request redirected to root domain from www subdomain");
         }
 
         public static void RewriteMiddlewareRequestContinueResults(this ILogger logger, string currentUrl)
@@ -135,6 +141,11 @@ namespace Microsoft.AspNetCore.Rewrite.Logging
             _redirectedToWww(logger, null);
         }
 
+        public static void RedirectedToNonWww(this ILogger logger)
+        {
+            _redirectedToNonWww(logger, null);
+        }
+
         public static void RedirectedRequest(this ILogger logger, string redirectedUrl)
         {
             _redirectedRequest(logger, redirectedUrl, null);

src/Middleware/Rewrite/src/RedirectToNonWwwRule.cs

@@ -0,0 +1,64 @@
+// 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.Http;
+using Microsoft.AspNetCore.Rewrite.Logging;
+
+namespace Microsoft.AspNetCore.Rewrite
+{
+    internal class RedirectToNonWwwRule : IRule
+    {
+        private const string WwwDot = "www.";
+
+        private readonly string[] _domains;
+        private readonly int _statusCode;
+
+        public RedirectToNonWwwRule(int statusCode)
+        {
+            _statusCode = statusCode;
+        }
+
+        public RedirectToNonWwwRule(int statusCode, params string[] domains)
+        {
+            if (domains == null)
+            {
+                throw new ArgumentNullException(nameof(domains));
+            }
+
+            if (domains.Length < 1)
+            {
+                throw new ArgumentException($"One or more {nameof(domains)} must be provided.");
+            }
+
+            _domains = domains;
+            _statusCode = statusCode;
+        }
+
+        public void ApplyRule(RewriteContext context)
+        {
+            var request = context.HttpContext.Request;
+
+            var hostInDomains = RedirectToWwwHelper.IsHostInDomains(request, _domains);
+
+            if (!hostInDomains)
+            {
+                context.Result = RuleResult.ContinueRules;
+                return;
+            }
+
+            if (!request.Host.Value.StartsWith(WwwDot, StringComparison.OrdinalIgnoreCase))
+            {
+                context.Result = RuleResult.ContinueRules;
+                return;
+            }
+
+            RedirectToWwwHelper.SetRedirect(
+                context,
+                new HostString(request.Host.Value.Substring(4)), // We verified the hostname begins with "www." already.
+                _statusCode);
+
+            context.Logger.RedirectedToNonWww();
+        }
+    }
+}

src/Middleware/Rewrite/src/RedirectToWwwHelper.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 Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Extensions;
+using Microsoft.Net.Http.Headers;
+
+namespace Microsoft.AspNetCore.Rewrite
+{
+    internal static class RedirectToWwwHelper
+    {
+        private const string Localhost = "localhost";
+
+        public static bool IsHostInDomains(HttpRequest request, string[] domains)
+        {
+            if (request.Host.Host.Equals(Localhost, StringComparison.OrdinalIgnoreCase))
+            {
+                return false;
+            }
+
+            if (domains != null)
+            {
+                var isHostInDomains = false;
+
+                foreach (var domain in domains)
+                {
+                    if (domain.Equals(request.Host.Host, StringComparison.OrdinalIgnoreCase))
+                    {
+                        isHostInDomains = true;
+                        break;
+                    }
+                }
+
+                if (!isHostInDomains)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        public static void SetRedirect(RewriteContext context, HostString newHost, int statusCode)
+        {
+            var request = context.HttpContext.Request;
+            var response = context.HttpContext.Response;
+
+            var newUrl = UriHelper.BuildAbsolute(
+                request.Scheme,
+                newHost,
+                request.PathBase,
+                request.Path,
+                request.QueryString);
+
+            response.StatusCode = statusCode;
+            response.Headers[HeaderNames.Location] = newUrl;
+            context.Result = RuleResult.EndResponse;
+        }
+    }
+}

src/Middleware/Rewrite/src/RedirectToWwwRule.cs

@@ -3,16 +3,16 @@
 
 using System;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Rewrite.Logging;
-using Microsoft.Net.Http.Headers;
 
 namespace Microsoft.AspNetCore.Rewrite
 {
     internal class RedirectToWwwRule : IRule
     {
-        public readonly int _statusCode;
+        private const string WwwDot = "www.";
-        public readonly string[] _domains;
+
+        private readonly string[] _domains;
+        private readonly int _statusCode;
 
         public RedirectToWwwRule(int statusCode)
         {
@@ -28,55 +28,36 @@ namespace Microsoft.AspNetCore.Rewrite
 
             if (domains.Length < 1)
             {
-                throw new ArgumentException(nameof(domains));
+                throw new ArgumentException($"One or more {nameof(domains)} must be provided.");
             }
 
             _domains = domains;
             _statusCode = statusCode;
         }
 
-        public virtual void ApplyRule(RewriteContext context)
+        public void ApplyRule(RewriteContext context)
         {
             var req = context.HttpContext.Request;
 
-            if (req.Host.Host.Equals("localhost", StringComparison.OrdinalIgnoreCase))
+            var hostInDomains = RedirectToWwwHelper.IsHostInDomains(req, _domains);
+
+            if (!hostInDomains)
             {
                 context.Result = RuleResult.ContinueRules;
                 return;
             }
 
-            if (req.Host.Value.StartsWith("www.", StringComparison.OrdinalIgnoreCase))
+            if (req.Host.Value.StartsWith(WwwDot, StringComparison.OrdinalIgnoreCase))
             {
                 context.Result = RuleResult.ContinueRules;
                 return;
             }
 
-            if (_domains != null)
+            RedirectToWwwHelper.SetRedirect(
-            {
+                context,
-                var isHostInDomains = false;
+                new HostString($"www.{context.HttpContext.Request.Host.Value}"),
+                _statusCode);
 
-                foreach (var domain in _domains)
-                {
-                    if (domain.Equals(req.Host.Host, StringComparison.OrdinalIgnoreCase))
-                    {
-                        isHostInDomains = true;
-                        break;
-                    }
-                }
-
-                if (!isHostInDomains)
-                {
-                    context.Result = RuleResult.ContinueRules;
-                    return;
-                }
-            }
-
-            var wwwHost = new HostString($"www.{req.Host.Value}");
-            var newUrl = UriHelper.BuildAbsolute(req.Scheme, wwwHost, req.PathBase, req.Path, req.QueryString);
-            var response = context.HttpContext.Response;
-            response.StatusCode = _statusCode;
-            response.Headers[HeaderNames.Location] = newUrl;
-            context.Result = RuleResult.EndResponse;
             context.Logger.RedirectedToWww();
         }
     }

src/Middleware/Rewrite/src/RewriteOptionsExtensions.cs

@@ -179,5 +179,68 @@ namespace Microsoft.AspNetCore.Rewrite
             options.Rules.Add(new RedirectToWwwRule(statusCode, domains));
             return options;
         }
+
+        /// <summary>
+        /// Permanently redirects the request to the root domain if the request is from the www subdomain.
+        /// </summary>
+        /// <param name="options">The <see cref="RewriteOptions"/>.</param>
+        /// <returns></returns>
+        public static RewriteOptions AddRedirectToNonWwwPermanent(this RewriteOptions options)
+        {
+            return AddRedirectToNonWww(options, statusCode: StatusCodes.Status308PermanentRedirect);
+        }
+
+        /// <summary>
+        /// Permanently redirects the request to the root domain if the request is from the www subdomain.
+        /// </summary>
+        /// <param name="options">The <see cref="RewriteOptions"/>.</param>
+        /// <param name="domains">Limit the rule to apply only on the specified domain(s).</param>
+        /// <returns></returns>
+        public static RewriteOptions AddRedirectToNonWwwPermanent(this RewriteOptions options, params string[] domains)
+        {
+            return AddRedirectToNonWww(options, statusCode: StatusCodes.Status308PermanentRedirect, domains);
+        }
+
+        /// <summary>
+        /// Redirect the request to the root domain if the incoming request is from the www subdomain.
+        /// </summary>
+        /// <param name="options">The <see cref="RewriteOptions"/>.</param>
+        public static RewriteOptions AddRedirectToNonWww(this RewriteOptions options)
+        {
+            return AddRedirectToNonWww(options, statusCode: StatusCodes.Status307TemporaryRedirect);
+        }
+
+        /// <summary>
+        /// Redirect the request to the root domain if the incoming request is from the www subdomain.
+        /// </summary>
+        /// <param name="options">The <see cref="RewriteOptions"/>.</param>
+        /// <param name="domains">Limit the rule to apply only on the specified domain(s).</param>
+        public static RewriteOptions AddRedirectToNonWww(this RewriteOptions options, params string[] domains)
+        {
+            return AddRedirectToNonWww(options, statusCode: StatusCodes.Status307TemporaryRedirect, domains);
+        }
+
+        /// <summary>
+        /// Redirect the request to the root domain if the incoming request is from the www subdomain.
+        /// </summary>
+        /// <param name="options">The <see cref="RewriteOptions"/>.</param>
+        /// <param name="statusCode">The status code to add to the response.</param>
+        public static RewriteOptions AddRedirectToNonWww(this RewriteOptions options, int statusCode)
+        {
+            options.Rules.Add(new RedirectToNonWwwRule(statusCode));
+            return options;
+        }
+
+        /// <summary>
+        /// Redirect the request to the root domain if the incoming request is from the www subdomain.
+        /// </summary>
+        /// <param name="options">The <see cref="RewriteOptions"/>.</param>
+        /// <param name="statusCode">The status code to add to the response.</param>
+        /// <param name="domains">Limit the rule to apply only on the specified domain(s).</param>
+        public static RewriteOptions AddRedirectToNonWww(this RewriteOptions options, int statusCode, params string[] domains)
+        {
+            options.Rules.Add(new RedirectToNonWwwRule(statusCode, domains));
+            return options;
+        }
     }
 }

src/Middleware/Rewrite/test/MiddlewareTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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;
@@ -232,6 +232,65 @@ namespace Microsoft.AspNetCore.Rewrite.Tests.CodeRules
             Assert.Null(response.Headers.Location);
         }
 
+        [Theory]
+        [InlineData(StatusCodes.Status301MovedPermanently)]
+        [InlineData(StatusCodes.Status302Found)]
+        [InlineData(StatusCodes.Status307TemporaryRedirect)]
+        [InlineData(StatusCodes.Status308PermanentRedirect)]
+        public async Task CheckRedirectToNonWwwWithStatusCode(int statusCode)
+        {
+            var options = new RewriteOptions().AddRedirectToNonWww(statusCode: statusCode);
+            var builder = new WebHostBuilder()
+            .Configure(app =>
+            {
+                app.UseRewriter(options);
+            });
+            var server = new TestServer(builder);
+
+            var response = await server.CreateClient().GetAsync(new Uri("https://www.example.com"));
+
+            Assert.Equal("https://example.com/", response.Headers.Location.OriginalString);
+            Assert.Equal(statusCode, (int)response.StatusCode);
+        }
+
+        [Theory]
+        [InlineData("http://www.example.com", "http://example.com/")]
+        [InlineData("https://www.example.com", "https://example.com/")]
+        [InlineData("http://www.example.com:8081", "http://example.com:8081/")]
+        [InlineData("http://www.example.com:8081/example?q=1", "http://example.com:8081/example?q=1")]
+        public async Task CheckRedirectToNonWww(string requestUri, string redirectUri)
+        {
+            var options = new RewriteOptions().AddRedirectToNonWww();
+            var builder = new WebHostBuilder()
+                .Configure(app =>
+                {
+                    app.UseRewriter(options);
+                });
+            var server = new TestServer(builder);
+
+            var response = await server.CreateClient().GetAsync(new Uri(requestUri));
+
+            Assert.Equal(redirectUri, response.Headers.Location.OriginalString);
+            Assert.Equal(StatusCodes.Status307TemporaryRedirect, (int)response.StatusCode);
+        }
+
+        [Fact]
+        public async Task CheckPermanentRedirectToNonWww()
+        {
+            var options = new RewriteOptions().AddRedirectToNonWwwPermanent();
+            var builder = new WebHostBuilder()
+                .Configure(app =>
+                {
+                    app.UseRewriter(options);
+                });
+            var server = new TestServer(builder);
+
+            var response = await server.CreateClient().GetAsync(new Uri("https://www.example.com"));
+
+            Assert.Equal("https://example.com/", response.Headers.Location.OriginalString);
+            Assert.Equal(StatusCodes.Status308PermanentRedirect, (int)response.StatusCode);
+        }
+
         [Fact]
         public async Task CheckIfEmptyStringRedirectCorrectly()
         {