fix 304 (#22647)

Author: kasobol-msft

sdk/storage/Azure.Storage.Blobs/CHANGELOG.md

@@ -13,6 +13,7 @@
 - Added support for RequestConditions parameter validation.  If a request condition is set for an API that doesn't support it, and ArguementException will be thrown.
     - This feature can be disabled with the environment variable "AZURE_STORAGE_DISABLE_REQUEST_CONDITIONS_VALIDATION" or the App Context switch "Azure.Storage.DisableRequestConditionsValidation".
 - Fixed bug where BlobBaseClient.DownloadStreamingAsync() won't correctly parse the LeaseStatus header.
+- Fixed bug where BlobBaseClient.DownloadContentAsync() fails on 304 response.
 
 ## 12.9.1 (2021-06-23)
 - Added optimization to unwrap encryption key once for DownloadTo and OpenRead when Client Side Encryption is enabled.

sdk/storage/Azure.Storage.Blobs/src/BlobBaseClient.cs

@@ -946,6 +946,13 @@ private async Task<Response<BlobDownloadInfo>> DownloadInternal(
                 $"{nameof(BlobBaseClient)}.{nameof(Download)}",
                 async,
                 cancellationToken).ConfigureAwait(false);
+
+            // Return an exploding Response on 304
+            if (response.IsUnavailable())
+            {
+                return response.GetRawResponse().AsNoBodyResponse<BlobDownloadInfo>();
+            }
+
             BlobDownloadStreamingResult blobDownloadStreamingResult = response.Value;
             BlobDownloadDetails blobDownloadDetails = blobDownloadStreamingResult.Details;
             return Response.FromValue(
@@ -1573,6 +1580,13 @@ private async Task<Response<BlobDownloadResult>> DownloadContentInternal(
                 operationName: $"{nameof(BlobBaseClient)}.{nameof(DownloadContent)}",
                 async: async,
                 cancellationToken: cancellationToken).ConfigureAwait(false);
+
+            // Return an exploding Response on 304
+            if (response.IsUnavailable())
+            {
+                return response.GetRawResponse().AsNoBodyResponse<BlobDownloadResult>();
+            }
+
             using BlobDownloadStreamingResult blobDownloadStreamingResult = response.Value;
             BinaryData data;
             if (async)

sdk/storage/Azure.Storage.Blobs/tests/BlobBaseClientTests.cs

@@ -1526,6 +1526,72 @@ public async Task DownloadTo_Initial304()
             Assert.AreEqual(304, result.Status);
         }
 
+        [RecordedTest]
+        public async Task DownloadContent_Initial304()
+        {
+            await using DisposingContainer test = await GetTestContainerAsync();
+
+            // Upload a blob
+            var data = GetRandomBuffer(Constants.KB);
+            BlobClient blob = InstrumentClient(test.Container.GetBlobClient(GetNewBlobName()));
+            using (var stream = new MemoryStream(data))
+            {
+                await blob.UploadAsync(stream);
+            }
+
+            // Add conditions to cause a failure and ensure we don't explode
+            Response<BlobDownloadResult> result = await blob.DownloadContentAsync(
+                new BlobRequestConditions
+                {
+                    IfModifiedSince = Recording.UtcNow
+                });
+            Assert.AreEqual(304, result.GetRawResponse().Status);
+        }
+
+        [RecordedTest]
+        public async Task DownloadStreaming_Initial304()
+        {
+            await using DisposingContainer test = await GetTestContainerAsync();
+
+            // Upload a blob
+            var data = GetRandomBuffer(Constants.KB);
+            BlobClient blob = InstrumentClient(test.Container.GetBlobClient(GetNewBlobName()));
+            using (var stream = new MemoryStream(data))
+            {
+                await blob.UploadAsync(stream);
+            }
+
+            // Add conditions to cause a failure and ensure we don't explode
+            Response<BlobDownloadStreamingResult> result = await blob.DownloadStreamingAsync(
+                conditions: new BlobRequestConditions
+                {
+                    IfModifiedSince = Recording.UtcNow
+                });
+            Assert.AreEqual(304, result.GetRawResponse().Status);
+        }
+
+        [RecordedTest]
+        public async Task Download_Initial304()
+        {
+            await using DisposingContainer test = await GetTestContainerAsync();
+
+            // Upload a blob
+            var data = GetRandomBuffer(Constants.KB);
+            BlobClient blob = InstrumentClient(test.Container.GetBlobClient(GetNewBlobName()));
+            using (var stream = new MemoryStream(data))
+            {
+                await blob.UploadAsync(stream);
+            }
+
+            // Add conditions to cause a failure and ensure we don't explode
+            Response<BlobDownloadInfo> result = await blob.DownloadAsync(
+                conditions: new BlobRequestConditions
+                {
+                    IfModifiedSince = Recording.UtcNow
+                });
+            Assert.AreEqual(304, result.GetRawResponse().Status);
+        }
+
         [RecordedTest]
         public async Task DownloadTo_ReplacedDuringDownload()
         {