[Service Bus] Fix error parsing logic (Azure#48156)

* [Service Bus] Fix error parsing logic

The focus of these changes is to fix the logic for
parsing error codes from the Service Bus administration
service.  The implementation assumes that all error
responses will have a content body, which is not always
the case.

For example, an HTTP 401 is returned without a body.
In this scenario, the error detail parsing faults
and surfaces an exception, obscuring the original
401 status code.

* Adding changelog

* Update sdk/servicebus/Azure.Messaging.ServiceBus/src/Administration/ServiceBusRequestFailedDetailsParser.cs

Co-authored-by: JoshLove-msft <[email protected]>

---------

Co-authored-by: JoshLove-msft <[email protected]>

Author: jsquire

sdk/servicebus/Azure.Messaging.ServiceBus/CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Bugs Fixed
 
+- Fixed an issue where an error response from the Service Bus administration service without a body was incorrectly parsed, resulting in a null argument exception obscuring the actual failure response. ([#47517](https://github.com/Azure/azure-sdk-for-net/issues/47517))
+
 ### Other Changes
 
 ## 7.18.3 (2025-01-17)

sdk/servicebus/Azure.Messaging.ServiceBus/src/Administration/ServiceBusRequestFailedDetailsParser.cs

@@ -15,7 +15,7 @@ internal sealed class ServiceBusRequestFailedDetailsParser : RequestFailedDetail
         public override bool TryParse(Response response, out ResponseError? error, out IDictionary<string, string>? data)
         {
             data = default;
-            if (response.ContentStream is { CanSeek: true })
+            if (response.ContentStream is { CanSeek: true, Length: > 0})
             {
                 var position = response.ContentStream.Position;
                 try

sdk/servicebus/Azure.Messaging.ServiceBus/tests/Administration/ServiceBusRequestFailedDetailsParserTests.cs

@@ -0,0 +1,77 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.IO;
+using Azure.Core.Pipeline;
+using Azure.Core.TestFramework;
+using Moq;
+using NUnit.Framework;
+
+namespace Azure.Messaging.ServiceBus.Tests.Administration
+{
+    [TestFixture]
+    public class ServiceBusRequestFailedDetailsParserTests
+    {
+        [Test]
+        public void ZeroLengthStreamReturnsDefaultErrorDetails()
+        {
+            var response = new MockResponse(401);
+            response.SetIsError(true);
+            response.SetContent(Array.Empty<byte>());
+
+            var parser = new ServiceBusRequestFailedDetailsParser();
+            parser.TryParse(response, out var error, out var data);
+
+            Assert.AreSame(default(ResponseError), error);
+        }
+
+        [Test]
+        public void NonSeekingStreamReturnsDefaultErrorDetails()
+        {
+            var mockStream = new Mock<Stream>();
+            var response = new MockResponse(401) { ContentStream = mockStream.Object };
+
+            mockStream
+                .Setup(stream => stream.CanSeek)
+                .Returns(false);
+
+            mockStream
+                .Setup(stream => stream.Length)
+                .Returns(1);
+
+            response.SetIsError(true);
+
+            var parser = new ServiceBusRequestFailedDetailsParser();
+            parser.TryParse(response, out var error, out var data);
+
+            Assert.AreSame(default(ResponseError), error);
+        }
+
+        [Test]
+        public void XmlBodyReturnsErrorDetails()
+        {
+            var subcCode = "40100";
+            var message = $"SubCode={subcCode}. Failed to authenticate";
+
+            var errorContent =
+                @$"<?xml version=""1.0"" encoding=""UTF-8""?>
+                <Error>
+                  <Code>401</Code>
+                  <Detail>{message}</Detail>
+                </Error>";
+
+            var response = new MockResponse(401);
+            response.SetIsError(true);
+            response.SetContent(errorContent);
+
+            var parser = new ServiceBusRequestFailedDetailsParser();
+            parser.TryParse(response, out var error, out var data);
+
+            Assert.NotNull(error);
+            Assert.AreNotSame(error, default(ResponseError));
+            Assert.AreEqual(subcCode, error.Code);
+            Assert.AreEqual(message, error.Message);
+        }
+    }
+}