Ensure that TestRecordingMismatchException doesn't exhaust default header size limits (#9662)

scbedd · web-flow · commit 034d14aae134 · 2025-01-21T10:49:14.000-08:00
* limit the size of the Remaining Entries output in the actual header of a TestRecordingMismatch exception. The message content's potential size could break the default limits on header size
* update tests to reflect new exception output
diff --git a/tools/test-proxy/Azure.Sdk.Tools.TestProxy.Tests/RecordSessionTests.cs b/tools/test-proxy/Azure.Sdk.Tools.TestProxy.Tests/RecordSessionTests.cs
@@ -408,7 +408,6 @@ public void RecordMatcherThrowsExceptionsWithDetails()
             TestRecordingMismatchException exception = Assert.Throws<TestRecordingMismatchException>(() => matcher.FindMatch(requestEntry, entries));
             Assert.Equal(
                 "Unable to find a record for the request HEAD http://localhost/" + Environment.NewLine +
-                "Remaining entry: http://remote-host" + Environment.NewLine +
                 "Method doesn't match, request <HEAD> record <PUT>" + Environment.NewLine +
                 "Uri doesn't match:" + Environment.NewLine +
                 "    request <http://localhost/>" + Environment.NewLine +
@@ -420,7 +419,9 @@ public void RecordMatcherThrowsExceptionsWithDetails()
                 "Body differences:" + Environment.NewLine +
                 "Request and record bodies do not match at index 40:" + Environment.NewLine +
                 "     request: \"e and long.\"" + Environment.NewLine +
-                "     record:  \"e and long but it also doesn't\"" + Environment.NewLine,
+                "     record:  \"e and long but it also doesn't\"" + Environment.NewLine +
+                "Remaining Entries:" + Environment.NewLine +
+                "0: http://remote-host" + Environment.NewLine,
                 exception.Message);
         }
 
diff --git a/tools/test-proxy/Azure.Sdk.Tools.TestProxy/Common/HttpExceptionMiddleware.cs b/tools/test-proxy/Azure.Sdk.Tools.TestProxy/Common/HttpExceptionMiddleware.cs
@@ -44,17 +44,18 @@ public async Task Invoke(HttpContext context)
                 response.StatusCode = statusCode;
                 response.ContentType = "application/json;";
 
-                var encodedException = Convert.ToBase64String(Encoding.UTF8.GetBytes(e.Message));
-
                 if (e is TestRecordingMismatchException)
                 {
                     response.Headers.Append("x-request-mismatch", "true");
-                    response.Headers.Append("x-request-mismatch-error", encodedException);
+
+                    // grab the exception up till Remaining Entries: which can potentially push the header size past the default limit of ~8k
+                    var onlyMisMatchMessage = e.Message.Split("Remaining Entries:")[0];
+                    response.Headers.Append("x-request-mismatch-error", Convert.ToBase64String(Encoding.UTF8.GetBytes(onlyMisMatchMessage)));
                 }
                 else
                 {
                     response.Headers.Append("x-request-known-exception", "true");
-                    response.Headers.Append("x-request-known-exception-error", encodedException);
+                    response.Headers.Append("x-request-known-exception-error", Convert.ToBase64String(Encoding.UTF8.GetBytes(e.Message)));
                 }
 
                 var bodyObj = new
diff --git a/tools/test-proxy/Azure.Sdk.Tools.TestProxy/Common/RecordMatcher.cs b/tools/test-proxy/Azure.Sdk.Tools.TestProxy/Common/RecordMatcher.cs
@@ -244,14 +244,6 @@ private string GenerateException(RecordEntry request, RecordEntry bestScoreEntry
             StringBuilder builder = new StringBuilder();
             builder.AppendLine($"Unable to find a record for the request {request.RequestMethod} {request.RequestUri}");
 
-            if (entries != null)
-            {
-                foreach (var entry in entries)
-                {
-                    builder.AppendLine($"Remaining entry: {entry.RequestUri}");
-                }
-            }
-
             if (bestScoreEntry == null)
             {
                 builder.AppendLine("No records to match.");
@@ -279,6 +271,15 @@ private string GenerateException(RecordEntry request, RecordEntry bestScoreEntry
             request.Request.TryGetContentType(out var contentType);
             CompareBodies(request.Request.Body, bestScoreEntry.Request.Body, contentType, descriptionBuilder: builder);
 
+            if (entries != null && entries.Count >= 1)
+            {
+                builder.AppendLine("Remaining Entries:");
+                for (int i = 0; i < entries.Count; i++)
+                {
+                    var entry = entries[i];
+                    builder.AppendLine($"{i}: {entry.RequestUri}");
+                }
+            }
             return builder.ToString();
         }
 

Original file line number	Diff line number	Diff line change
`@@ -44,17 +44,18 @@ public async Task Invoke(HttpContext context)`
`44`	`44`	`response.StatusCode = statusCode;`
`45`	`45`	`response.ContentType = "application/json;";`
`46`	`46`
`47`		`- var encodedException = Convert.ToBase64String(Encoding.UTF8.GetBytes(e.Message));`
`48`		`-`
`49`	`47`	`if (e is TestRecordingMismatchException)`
`50`	`48`	`{`
`51`	`49`	`response.Headers.Append("x-request-mismatch", "true");`
`52`		`- response.Headers.Append("x-request-mismatch-error", encodedException);`
	`50`	`+`
	`51`	`+ // grab the exception up till Remaining Entries: which can potentially push the header size past the default limit of ~8k`
	`52`	`+ var onlyMisMatchMessage = e.Message.Split("Remaining Entries:")[0];`
	`53`	`+ response.Headers.Append("x-request-mismatch-error", Convert.ToBase64String(Encoding.UTF8.GetBytes(onlyMisMatchMessage)));`
`53`	`54`	`}`
`54`	`55`	`else`
`55`	`56`	`{`
`56`	`57`	`response.Headers.Append("x-request-known-exception", "true");`
`57`		`- response.Headers.Append("x-request-known-exception-error", encodedException);`
	`58`	`+ response.Headers.Append("x-request-known-exception-error", Convert.ToBase64String(Encoding.UTF8.GetBytes(e.Message)));`
`58`	`59`	`}`
`59`	`60`
`60`	`61`	`var bodyObj = new`