check HTTP status code of NSURLConnection responses during xhr polling transport just like when checking HTTP status code during handshake. Handles case when server restarts while connection with device is already established.

Author: Allen Schober

SocketIOTransportXHR.m

@@ -171,6 +171,27 @@ - (void) poll:(NSString *)data retryNumber:(int)retry
 
 - (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
 {
+    // check for server status code (http://gigliwood.com/weblog/Cocoa/Q__When_is_an_conne.html)
+    if ([response respondsToSelector:@selector(statusCode)]) {
+        NSInteger statusCode = [((NSHTTPURLResponse *)response) statusCode];
+        DEBUGLOG(@"didReceiveResponse() %i", statusCode);
+        
+        if (statusCode >= 400) {
+            // stop connecting; no more delegate messages
+            [connection cancel];
+            
+            NSString *error = [NSString stringWithFormat:NSLocalizedString(@"Server returned status code %d", @""), statusCode];
+            NSDictionary *errorInfo = [NSDictionary dictionaryWithObject:error forKey:NSLocalizedDescriptionKey];
+            NSError *statusError = [NSError errorWithDomain:SocketIOError
+                                                       code:statusCode
+                                                   userInfo:errorInfo];
+            
+            if ([delegate respondsToSelector:@selector(onError:)]) {
+                [delegate onError:statusError];
+            }
+        }
+    }
+    
     [_data setLength:0];
 }