Return HTTP 404 if FileNotFoundException is thrown when attempting to send a file (#232)

src/Microsoft.AspNetCore.StaticFiles/StaticFileContext.cs

@@ -233,7 +233,7 @@ namespace Microsoft.AspNetCore.StaticFiles
                 // the Range header field.
                 if (ifRangeHeader.LastModified.HasValue)
                 {
-                    if (_lastModified !=null && _lastModified > ifRangeHeader.LastModified)
+                    if (_lastModified != null && _lastModified > ifRangeHeader.LastModified)
                     {
                         _isRangeRequest = false;
                     }
@@ -318,11 +318,11 @@ namespace Microsoft.AspNetCore.StaticFiles
 
         public async Task SendAsync()
         {
-            ApplyResponseHeaders(Constants.Status200Ok);
             string physicalPath = _fileInfo.PhysicalPath;
             var sendFile = _context.Features.Get<IHttpSendFileFeature>();
             if (sendFile != null && !string.IsNullOrEmpty(physicalPath))
             {
+                ApplyResponseHeaders(Constants.Status200Ok);
                 // We don't need to directly cancel this, if the client disconnects it will fail silently.
                 await sendFile.SendFileAsync(physicalPath, 0, _length, CancellationToken.None);
                 return;
@@ -332,6 +332,9 @@ namespace Microsoft.AspNetCore.StaticFiles
             {
                 using (var readStream = _fileInfo.CreateReadStream())
                 {
+                    // Don't apply headers until we are sure we can open this file.
+                    ApplyResponseHeaders(Constants.Status200Ok);
+
                     // Larger StreamCopyBufferSize is required because in case of FileStream readStream isn't going to be buffering
                     await StreamCopyOperation.CopyToAsync(readStream, _response.Body, _length, StreamCopyBufferSize, _context.RequestAborted);
                 }

src/Microsoft.AspNetCore.StaticFiles/StaticFileMiddleware.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Diagnostics;
+using System.IO;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
@@ -67,7 +68,7 @@ namespace Microsoft.AspNetCore.StaticFiles
         /// </summary>
         /// <param name="context"></param>
         /// <returns></returns>
-        public Task Invoke(HttpContext context)
+        public async Task Invoke(HttpContext context)
         {
             var fileContext = new StaticFileContext(context, _options, _matchUrl, _logger, _fileProvider, _contentTypeProvider);
 
@@ -97,21 +98,35 @@ namespace Microsoft.AspNetCore.StaticFiles
                     case StaticFileContext.PreconditionState.ShouldProcess:
                         if (fileContext.IsHeadMethod)
                         {
-                            return fileContext.SendStatusAsync(Constants.Status200Ok);
+                            await fileContext.SendStatusAsync(Constants.Status200Ok);
+                            return;
                         }
                         if (fileContext.IsRangeRequest)
                         {
-                            return fileContext.SendRangeAsync();
+                            await fileContext.SendRangeAsync();
+                            return;
+                        }
+                        try
+                        {
+                            await fileContext.SendAsync();
+                            _logger.LogFileServed(fileContext.SubPath, fileContext.PhysicalPath);
+                            return;
+                        }
+                        catch (FileNotFoundException)
+                        {
+                            _logger.LogFileNotFound(fileContext.SubPath);
+                            await fileContext.SendStatusAsync(StatusCodes.Status404NotFound);
+                            return;
                         }
-                        _logger.LogFileServed(fileContext.SubPath, fileContext.PhysicalPath);
-                        return fileContext.SendAsync();
                     case StaticFileContext.PreconditionState.NotModified:
                         _logger.LogPathNotModified(fileContext.SubPath);
-                        return fileContext.SendStatusAsync(Constants.Status304NotModified);
+                        await fileContext.SendStatusAsync(Constants.Status304NotModified);
+                        return;
 
                     case StaticFileContext.PreconditionState.PreconditionFailed:
                         _logger.LogPreconditionFailed(fileContext.SubPath);
-                        return fileContext.SendStatusAsync(Constants.Status412PreconditionFailed);
+                        await fileContext.SendStatusAsync(Constants.Status412PreconditionFailed);
+                        return;
 
                     default:
                         var exception = new NotImplementedException(fileContext.GetPreconditionState().ToString());
@@ -120,7 +135,7 @@ namespace Microsoft.AspNetCore.StaticFiles
                 }
             }
 
-            return _next(context);
+            await _next(context);
         }
     }
 }

test/Microsoft.AspNetCore.StaticFiles.Tests/StaticFileMiddlewareTests.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Net;
@@ -13,6 +14,7 @@ using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.AspNetCore.Testing.xunit;
 using Microsoft.Extensions.FileProviders;
+using Microsoft.Net.Http.Headers;
 using Xunit;
 
 namespace Microsoft.AspNetCore.StaticFiles
@@ -29,6 +31,27 @@ namespace Microsoft.AspNetCore.StaticFiles
             var response = await server.CreateClient().GetAsync("/ranges.txt");
 
             Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
+            Assert.Null(response.Headers.ETag);
+        }
+
+        [ConditionalFact]
+        [OSSkipCondition(OperatingSystems.Windows, SkipReason = "Symlinks not supported on Windows")]
+        public async Task ReturnsNotFoundForBrokenSymlink()
+        {
+            var badLink = Path.Combine(AppContext.BaseDirectory, Path.GetRandomFileName() + ".txt");
+
+            Process.Start("ln", $"-s \"/tmp/{Path.GetRandomFileName()}\" \"{badLink}\"").WaitForExit();
+            Assert.True(File.Exists(badLink), "Should have created a symlink");
+
+            var builder = new WebHostBuilder()
+                .Configure(app => app.UseStaticFiles(new StaticFileOptions { ServeUnknownFileTypes = true }))
+                .UseWebRoot(AppContext.BaseDirectory);
+            var server = new TestServer(builder);
+
+            var response = await server.CreateClient().GetAsync(Path.GetFileName(badLink));
+
+            Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
+            Assert.Null(response.Headers.ETag);
         }
 
         [Fact]
@@ -101,6 +124,7 @@ namespace Microsoft.AspNetCore.StaticFiles
                 Assert.Equal("text/plain", response.Content.Headers.ContentType.ToString());
                 Assert.True(response.Content.Headers.ContentLength == fileInfo.Length);
                 Assert.Equal(response.Content.Headers.ContentLength, responseContent.Length);
+                Assert.NotNull(response.Headers.ETag);
 
                 using (var stream = fileInfo.CreateReadStream())
                 {