Fix Accept-Encoding parsing

Fix `Accept-Encoding` parsing when there are multiple values or the value includes a quality.

See #3486 (comment).

Author: martincostello

src/Shared/EmbeddedResourceProvider.cs

@@ -87,11 +87,14 @@ public async Task<bool> TryRespondWithFileAsync(HttpContext httpContext)
 
     private static bool IsGZipAccepted(HttpRequest httpRequest)
     {
-        var acceptEncoding = httpRequest.Headers.AcceptEncoding;
+        if (httpRequest.GetTypedHeaders().AcceptEncoding is not { Count: > 0 } acceptEncoding)
+        {
+            return false;
+        }
 
         for (int i = 0; i < acceptEncoding.Count; i++)
         {
-            if (string.Equals(acceptEncoding[i], GZipEncodingValue, StringComparison.OrdinalIgnoreCase))
+            if (string.Equals(acceptEncoding[i]?.Value.Value, GZipEncodingValue, StringComparison.OrdinalIgnoreCase))
             {
                 return true;
             }

test/Swashbuckle.AspNetCore.IntegrationTests/ReDocIntegrationTests.cs

@@ -1,5 +1,6 @@
 using System.IO.Compression;
 using System.Net;
+using System.Net.Http.Headers;
 using System.Security.Cryptography;
 using Microsoft.AspNetCore.Builder;
 using Swashbuckle.AspNetCore.ReDoc;
@@ -219,8 +220,11 @@ public async Task ReDocMiddleware_Returns_ExpectedAssetContents_Decompressed()
         Assert.Equal(response.Content.Headers.ContentLength, actual.Length);
     }
 
-    [Fact]
-    public async Task ReDocMiddleware_Returns_ExpectedAssetContents_GZip_Compressed()
+    [Theory]
+    [InlineData("gzip")]
+    [InlineData("gzip;q=1.0, identity; q=0.5, *;q=0")]
+    [InlineData("gzip, deflate, br, zstd")]
+    public async Task ReDocMiddleware_Returns_ExpectedAssetContents_GZip_Compressed(string acceptEncoding)
     {
         // Arrange
         var cancellationToken = TestContext.Current.CancellationToken;
@@ -229,7 +233,15 @@ public async Task ReDocMiddleware_Returns_ExpectedAssetContents_GZip_Compressed(
         using var client = site.BuildClient();
 
         using var request = new HttpRequestMessage(HttpMethod.Get, "/Api-Docs/redoc.standalone.js");
-        request.Headers.AcceptEncoding.Add(new("gzip"));
+
+        var encodings = acceptEncoding.Split(',')
+            .Select((p) => p.Trim())
+            .ToList();
+
+        foreach (var encoding in encodings)
+        {
+            request.Headers.AcceptEncoding.Add(StringWithQualityHeaderValue.Parse(encoding));
+        }
 
         // Act
         using var response = await client.SendAsync(request, cancellationToken);