From dc2ecc787b65c1b87de9cb841989df8eee032e24 Mon Sep 17 00:00:00 2001
From: Aadharsh Pannirselvam <19518661+oddharsh@users.noreply.github.com>
Date: Thu, 3 Sep 2026 13:51:25 -0400
Subject: [PATCH] Surface HTTP errors from GSA auth instead of a plist parse
 failure

gsa.apple.com/grandslam/GsService2 occasionally responds to the auth
request with a plain HTTP error page (e.g. 503 Service Temporarily
Unavailable) instead of a plist body. sendAuthenticationRequestWithParameters:
fed that HTML straight into NSPropertyListSerialization, which failed with
"Encountered unknown tag html on line 1" / kCFPropertyListOldStyleParsingError
- a confusing, low-level error that gives no hint the real issue is a
transient server error on Apple's end.

Check the response status code before parsing and return a clear,
actionable error when it's non-2xx.
---
 AltSign/Apple API/ALTAppleAPI+Authentication.m | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/AltSign/Apple API/ALTAppleAPI+Authentication.m b/AltSign/Apple API/ALTAppleAPI+Authentication.m
index 7a459756..6cf3b684 100644
--- a/AltSign/Apple API/ALTAppleAPI+Authentication.m	
+++ b/AltSign/Apple API/ALTAppleAPI+Authentication.m	
@@ -713,6 +713,21 @@ - (void)sendAuthenticationRequestWithParameters:(NSDictionary *)requestDictionar
             return;
         }
         
+        // Apple's GSA endpoint occasionally responds to this request with a plain
+        // HTTP error page (e.g. 503 Service Temporarily Unavailable) instead of a
+        // plist body. Parsing that HTML as a plist below fails with a confusing,
+        // low-level "unknown tag html" / kCFPropertyListOldStyleParsingError, which
+        // gives no indication the actual problem is a transient server error. Check
+        // the status code first so that case gets a clear, actionable message.
+        NSHTTPURLResponse *httpResponse = [response isKindOfClass:[NSHTTPURLResponse class]] ? (NSHTTPURLResponse *)response : nil;
+        if (httpResponse != nil && (httpResponse.statusCode < 200 || httpResponse.statusCode >= 300))
+        {
+            NSString *localizedDescription = [NSString stringWithFormat:@"Apple's servers returned an error while authenticating (HTTP %@). Please try again later.", @(httpResponse.statusCode)];
+            NSError *error = [NSError errorWithDomain:ALTAppleAPIErrorDomain code:ALTAppleAPIErrorUnknown userInfo:@{NSLocalizedDescriptionKey: localizedDescription}];
+            completionHandler(nil, error);
+            return;
+        }
+
         NSError *parseError = nil;
         NSDictionary *responseDictionary = [NSPropertyListSerialization propertyListWithData:data options:0 format:nil error:&parseError];