Fix retrieval of bodies larger than the large object heap but below the maximum body size to store

src/ServiceControl.AcceptanceTesting/InfrastructureConfig/ConfigureEndpointLearningTransport.cs

@@ -15,6 +15,7 @@ public Task Configure(string endpointName, EndpointConfiguration configuration,
 
             var transportConfig = configuration.UseTransport<LearningTransport>();
             transportConfig.StorageDirectory(ConnectionString);
+            transportConfig.NoPayloadSizeRestriction();
 
             return Task.FromResult(0);
         }

src/ServiceControl.Audit.AcceptanceTests/Auditing/When_messages_with_big_bodies_are_ingested.cs

@@ -93,7 +93,49 @@ await Define<Context>()
             Assert.AreEqual(0, body.Length);
         }
 
+        [Test]
+        public async Task Should_not_get_an_empty_audit_message_body_when_body_is_above_loh_but_below_max_body_size()
+        {
+            //Arrange
+            SetSettings = settings => settings.MaxBodySizeToStore = 2* MAX_BODY_SIZE_BIGGER_THAN_LOH;
+
+            byte[] body = null;
+
+            //Act
+            await Define<Context>()
+                .WithEndpoint<FatMessageEndpoint>(c => c.When(b => b.SendLocal(
+                    new BigFatMessage // An endpoint that is configured for audit
+                    {
+                        BigFatBody = new byte[MAX_BODY_SIZE_BIGGER_THAN_LOH]
+                    }))
+                )
+                .Done(
+                    async c =>
+                    {
+                        if (c.MessageId == null)
+                        {
+                            return false;
+                        }
+
+                        var result = await this.TryGetSingle<MessagesView>("/api/messages", r => r.MessageId == c.MessageId);
+                        MessagesView auditMessage = result;
+                        if (!result)
+                        {
+                            return false;
+                        }
+
+                        body = await this.DownloadData(auditMessage.BodyUrl);
+
+                        return true;
+                    })
+                .Run();
+
+            //Assert
+            Assert.IsNotNull(body);
+        }
+
         const int MAX_BODY_SIZE = 20536;
+        const int MAX_BODY_SIZE_BIGGER_THAN_LOH = 87000;
 
         class FatMessageEndpoint : EndpointConfigurationBuilder
         {

src/ServiceControl.Audit/Auditing/GetBodyByIdApi.cs

@@ -46,6 +46,7 @@ async Task<HttpResponseMessage> TryFetchFromStorage(HttpRequestMessage request,
                 content.Headers.ContentLength = result.BodySize;
                 response.Headers.ETag = new EntityTagHeaderValue($"\"{result.Etag}\"");
                 response.Content = content;
+                return response;
             }
 
             return request.CreateResponse(HttpStatusCode.NotFound);
@@ -70,7 +71,12 @@ async Task<HttpResponseMessage> TryFetchFromIndex(HttpRequestMessage request, st
                 {
                     return request.CreateResponse(HttpStatusCode.NoContent);
                 }
-
+
+                if (message.Body == null)
+                {
+                    return request.CreateResponse(HttpStatusCode.NotFound);
+                }
+
                 var response = request.CreateResponse(HttpStatusCode.OK);
                 var content = new StringContent(message.Body);
                 content.Headers.ContentType = MediaTypeHeaderValue.Parse(message.ContentType);