Add support for port 0 in HttpSys (#13841)

src/Hosting/Server.IntegrationTesting/src/Common/TestPortHelper.cs

@@ -56,34 +56,5 @@ namespace Microsoft.AspNetCore.Server.IntegrationTesting.Common
                 }
             }
         }
-
-        private const int BasePort = 5001;
-        private const int MaxPort = 8000;
-        private static int NextPort = BasePort;
-
-        // GetNextPort doesn't check for HttpSys urlacls.
-        public static int GetNextHttpSysPort(string scheme)
-        {
-            while (NextPort < MaxPort)
-            {
-                var port = NextPort++;
-
-                using (var server = new HttpListener())
-                {
-                    server.Prefixes.Add($"{scheme}://localhost:{port}/");
-                    try
-                    {
-                        server.Start();
-                        server.Stop();
-                        return port;
-                    }
-                    catch (HttpListenerException)
-                    {
-                    }
-                }
-            }
-            NextPort = BasePort;
-            throw new Exception("Failed to locate a free port.");
-        }
     }
 }

src/Hosting/Server.IntegrationTesting/src/Common/TestUriHelper.cs

@@ -1,7 +1,9 @@
-// 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;
+using System.Diagnostics;
+
 namespace Microsoft.AspNetCore.Server.IntegrationTesting.Common
 {
     public static class TestUriHelper
@@ -34,7 +36,8 @@ namespace Microsoft.AspNetCore.Server.IntegrationTesting.Common
                 }
                 else if (serverType == ServerType.HttpSys)
                 {
-                    return new UriBuilder(scheme, "localhost", TestPortHelper.GetNextHttpSysPort(scheme)).Uri;
+                    Debug.Assert(scheme == "http", "Https not supported");
+                    return new UriBuilder(scheme, "localhost", 0).Uri;
                 }
                 else
                 {

src/Servers/HttpSys/src/MessagePump.cs

@@ -2,16 +2,18 @@
 // 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.Diagnostics.Contracts;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Hosting.Server.Features;
 using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.HttpSys.Internal;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using Microsoft.AspNetCore.HttpSys.Internal;
 
 namespace Microsoft.AspNetCore.Server.HttpSys
 {
@@ -74,6 +76,8 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             }
 
             var hostingUrlsPresent = _serverAddresses.Addresses.Count > 0;
+            var serverAddressCopy = _serverAddresses.Addresses.ToList();
+            _serverAddresses.Addresses.Clear();
 
             if (_serverAddresses.PreferHostingUrls && hostingUrlsPresent)
             {
@@ -85,10 +89,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
                     Listener.Options.UrlPrefixes.Clear();
                 }
 
-                foreach (var value in _serverAddresses.Addresses)
+                UpdateUrlPrefixes(serverAddressCopy);
-                {
-                    Listener.Options.UrlPrefixes.Add(value);
-                }
             }
             else if (_options.UrlPrefixes.Count > 0)
             {
@@ -100,23 +101,15 @@ namespace Microsoft.AspNetCore.Server.HttpSys
                     _serverAddresses.Addresses.Clear();
                 }
 
-                foreach (var prefix in _options.UrlPrefixes)
-                {
-                    _serverAddresses.Addresses.Add(prefix.FullPrefix);
-                }
             }
             else if (hostingUrlsPresent)
             {
-                foreach (var value in _serverAddresses.Addresses)
+                UpdateUrlPrefixes(serverAddressCopy);
-                {
-                    Listener.Options.UrlPrefixes.Add(value);
-                }
             }
             else
             {
                 LogHelper.LogDebug(_logger, $"No listening endpoints were configured. Binding to {Constants.DefaultServerAddress} by default.");
 
-                _serverAddresses.Addresses.Add(Constants.DefaultServerAddress);
                 Listener.Options.UrlPrefixes.Add(Constants.DefaultServerAddress);
             }
 
@@ -129,6 +122,13 @@ namespace Microsoft.AspNetCore.Server.HttpSys
 
             Listener.Start();
 
+            // Update server addresses after we start listening as port 0
+            // needs to be selected at the point of binding.
+            foreach (var prefix in _options.UrlPrefixes)
+            {
+                _serverAddresses.Addresses.Add(prefix.FullPrefix);
+            }
+
             ActivateRequestProcessingLimits();
 
             return Task.CompletedTask;
@@ -142,6 +142,14 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             }
         }
 
+        private void UpdateUrlPrefixes(IList<string> serverAddressCopy)
+        {
+            foreach (var value in serverAddressCopy)
+            {
+                Listener.Options.UrlPrefixes.Add(value);
+            }
+        }
+
         // The message pump.
         // When we start listening for the next request on one thread, we may need to be sure that the
         // completion continues on another thread as to not block the current request processing.

src/Servers/HttpSys/src/NativeInterop/UrlGroup.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;
@@ -73,7 +73,6 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         {
             LogHelper.LogInfo(_logger, "Listening on prefix: " + uriPrefix);
             CheckDisposed();
-
             var statusCode = HttpApi.HttpAddUrlToUrlGroup(Id, uriPrefix, (ulong)contextId, 0);
 
             if (statusCode != UnsafeNclNativeMethods.ErrorCodes.ERROR_SUCCESS)

src/Servers/HttpSys/src/UrlPrefixCollection.cs

@@ -1,8 +1,13 @@
-// 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;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Runtime.InteropServices;
+using Microsoft.AspNetCore.HttpSys.Internal;
 
 namespace Microsoft.AspNetCore.Server.HttpSys
 {
@@ -15,6 +20,12 @@ namespace Microsoft.AspNetCore.Server.HttpSys
         private UrlGroup _urlGroup;
         private int _nextId = 1;
 
+        // Valid port range of 5000 - 48000.
+        private const int BasePort = 5000;
+        private const int MaxPortIndex = 43000;
+        private const int MaxRetries = 1000;
+        private static int NextPortIndex;
+
         internal UrlPrefixCollection()
         {
         }
@@ -138,10 +149,55 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             {
                 _urlGroup = urlGroup;
                 // go through the uri list and register for each one of them
-                foreach (var pair in _prefixes)
+                // Call ToList to avoid modification when enumerating.
+                foreach (var pair in _prefixes.ToList())
                 {
-                    // We'll get this index back on each request and use it to look up the prefix to calculate PathBase.
+                    var urlPrefix = pair.Value;
-                    _urlGroup.RegisterPrefix(pair.Value.FullPrefix, pair.Key);
+                    if (urlPrefix.PortValue == 0)
+                    {
+                        if (urlPrefix.IsHttps)
+                        {
+                            throw new InvalidOperationException("Cannot bind to port 0 with https.");
+                        }
+
+                        FindHttpPortUnsynchronized(pair.Key, urlPrefix);
+                    }
+                    else
+                    {
+                        // We'll get this index back on each request and use it to look up the prefix to calculate PathBase.
+                        _urlGroup.RegisterPrefix(pair.Value.FullPrefix, pair.Key);
+                    }
+                }
+            }
+        }
+
+        private void FindHttpPortUnsynchronized(int key, UrlPrefix urlPrefix)
+        {
+            for (var index = 0; index < MaxRetries; index++)
+            {
+                try
+                {
+                    // Bit of complicated math to always try 3000 ports, starting from NextPortIndex + 5000,
+                    // circling back around if we go above 8000 back to 5000, and so on.
+                    var port = ((index + NextPortIndex) % MaxPortIndex) + BasePort;
+
+                    Debug.Assert(port >= 5000 || port < 8000);
+
+                    var newPrefix = UrlPrefix.Create(urlPrefix.Scheme, urlPrefix.Host, port, urlPrefix.Path);
+                    _urlGroup.RegisterPrefix(newPrefix.FullPrefix, key);
+                    _prefixes[key] = newPrefix;
+
+                    NextPortIndex += index + 1;
+                    return;
+                }
+                catch (HttpSysException ex)
+                {
+                    if ((ex.ErrorCode != UnsafeNclNativeMethods.ErrorCodes.ERROR_ACCESS_DENIED
+                        && ex.ErrorCode != UnsafeNclNativeMethods.ErrorCodes.ERROR_SHARING_VIOLATION
+                        && ex.ErrorCode != UnsafeNclNativeMethods.ErrorCodes.ERROR_ALREADY_EXISTS) || index == MaxRetries - 1)
+                    {
+                        throw;
+                    }
                 }
             }
         }
@@ -159,4 +215,4 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             }
         }
     }
-}
+}

src/Servers/HttpSys/startvs.cmd

@@ -0,0 +1,3 @@
+@ECHO OFF
+
+%~dp0..\..\..\startvs.cmd %~dp0HttpSysServer.sln

src/Servers/HttpSys/test/FunctionalTests/MessagePumpTests.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.Linq;
@@ -114,7 +114,8 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             {
                 server.StartAsync(new DummyApplication(), CancellationToken.None).Wait();
 
-                Assert.Equal(Constants.DefaultServerAddress, server.Features.Get<IServerAddressesFeature>().Addresses.Single());
+                // Trailing slash is added when put in UrlPrefix.
+                Assert.StartsWith(Constants.DefaultServerAddress, server.Features.Get<IServerAddressesFeature>().Addresses.Single());
             }
         }
 

src/Servers/HttpSys/test/FunctionalTests/Utilities.cs

@@ -2,6 +2,7 @@
 // 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.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Authentication;
@@ -21,11 +22,8 @@ namespace Microsoft.AspNetCore.Server.HttpSys
     {
         // When tests projects are run in parallel, overlapping port ranges can cause a race condition when looking for free
         // ports during dynamic port allocation.
-        private const int BasePort = 5001;
-        private const int MaxPort = 8000;
         private const int BaseHttpsPort = 44300;
         private const int MaxHttpsPort = 44399;
-        private static int NextPort = BasePort;
         private static int NextHttpsPort = BaseHttpsPort;
         private static object PortLock = new object();
         internal static readonly TimeSpan DefaultTimeout = TimeSpan.FromSeconds(15);
@@ -84,39 +82,26 @@ namespace Microsoft.AspNetCore.Server.HttpSys
 
         internal static IWebHost CreateDynamicHost(string basePath, out string root, out string baseAddress, Action<HttpSysOptions> configureOptions, RequestDelegate app)
         {
-            lock (PortLock)
+            var prefix = UrlPrefix.Create("http", "localhost", "0", basePath);
-            {
+
-                while (NextPort < MaxPort)
+            var builder = new WebHostBuilder()
+                .UseHttpSys(options =>
                 {
-                    var port = NextPort++;
+                    options.UrlPrefixes.Add(prefix);
-                    var prefix = UrlPrefix.Create("http", "localhost", port, basePath);
+                    configureOptions(options);
-                    root = prefix.Scheme + "://" + prefix.Host + ":" + prefix.Port;
+                })
-                    baseAddress = prefix.ToString();
+                .Configure(appBuilder => appBuilder.Run(app));
 
-                    var builder = new WebHostBuilder()
+            var host = builder.Build();
-                        .UseHttpSys(options =>
-                        {
-                            options.UrlPrefixes.Add(prefix);
-                            configureOptions(options);
-                        })
-                        .Configure(appBuilder => appBuilder.Run(app));
 
-                    var host = builder.Build();
+            host.Start();
 
+            var options = host.Services.GetRequiredService<IOptions<HttpSysOptions>>();
+            prefix = options.Value.UrlPrefixes.First(); // Has new port
+            root = prefix.Scheme + "://" + prefix.Host + ":" + prefix.Port;
+            baseAddress = prefix.ToString();
 
-                    try
+            return host;
-                    {
-                        host.Start();
-                        return host;
-                    }
-                    catch (HttpSysException)
-                    {
-                    }
-
-                }
-                NextPort = BasePort;
-            }
-            throw new Exception("Failed to locate a free port.");
         }
 
         internal static MessagePump CreatePump()
@@ -124,31 +109,18 @@ namespace Microsoft.AspNetCore.Server.HttpSys
 
         internal static IServer CreateDynamicHttpServer(string basePath, out string root, out string baseAddress, Action<HttpSysOptions> configureOptions, RequestDelegate app)
         {
-            lock (PortLock)
+            var prefix = UrlPrefix.Create("http", "localhost", "0", basePath);
-            {
-                while (NextPort < MaxPort)
-                {
 
-                    var port = NextPort++;
+            var server = CreatePump();
-                    var prefix = UrlPrefix.Create("http", "localhost", port, basePath);
+            server.Features.Get<IServerAddressesFeature>().Addresses.Add(prefix.ToString());
-                    root = prefix.Scheme + "://" + prefix.Host + ":" + prefix.Port;
+            configureOptions(server.Listener.Options);
-                    baseAddress = prefix.ToString();
+            server.StartAsync(new DummyApplication(app), CancellationToken.None).Wait();
 
-                    var server = CreatePump();
+            prefix = server.Listener.Options.UrlPrefixes.First(); // Has new port
-                    server.Features.Get<IServerAddressesFeature>().Addresses.Add(baseAddress);
+            root = prefix.Scheme + "://" + prefix.Host + ":" + prefix.Port;
-                    configureOptions(server.Listener.Options);
+            baseAddress = prefix.ToString();
-                    try
+
-                    {
+            return server;
-                        server.StartAsync(new DummyApplication(app), CancellationToken.None).Wait();
-                        return server;
-                    }
-                    catch (HttpSysException)
-                    {
-                    }
-                }
-                NextPort = BasePort;
-            }
-            throw new Exception("Failed to locate a free port.");
         }
 
         internal static IServer CreateDynamicHttpsServer(out string baseAddress, RequestDelegate app)
@@ -184,6 +156,7 @@ namespace Microsoft.AspNetCore.Server.HttpSys
             throw new Exception("Failed to locate a free port.");
         }
 
+
         internal static Task WithTimeout(this Task task) => task.TimeoutAfter(DefaultTimeout);
 
         internal static Task<T> WithTimeout<T>(this Task<T> task) => task.TimeoutAfter(DefaultTimeout);

src/Servers/HttpSys/test/Tests/UrlPrefixTests.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;

src/Shared/HttpSys/NativeInterop/UnsafeNativeMethods.cs

@@ -24,6 +24,8 @@ namespace Microsoft.AspNetCore.HttpSys.Internal
         internal static class ErrorCodes
         {
             internal const uint ERROR_SUCCESS = 0;
+            internal const uint ERROR_ACCESS_DENIED = 5;
+            internal const uint ERROR_SHARING_VIOLATION = 32;
             internal const uint ERROR_HANDLE_EOF = 38;
             internal const uint ERROR_NOT_SUPPORTED = 50;
             internal const uint ERROR_INVALID_PARAMETER = 87;