First try download and only if it fails try to fetch new download URL

Try is to allow us choose not to expire download links for automatic updates later.

Source commit: e93f81d044519c2587df7ad25a4fd83e4ab6a609

source/windows/Setup.cpp

@@ -1189,7 +1189,6 @@ private:
   std::unique_ptr<Exception> FException;
   std::unique_ptr<THttp> FHttp;
   TUpdatesConfiguration FUpdates;
-  UnicodeString FDownloadUrl;
 };
 //---------------------------------------------------------------------------
 __fastcall TUpdateDownloadThread::TUpdateDownloadThread(TProgressBar * ProgressBar) :
@@ -1209,44 +1208,55 @@ __fastcall TUpdateDownloadThread::~TUpdateDownloadThread()
 //---------------------------------------------------------------------------
 void __fastcall TUpdateDownloadThread::Execute()
 {
-  FDownloadUrl = FUpdates.Results.DownloadUrl;
-
-  // If the download URL is too old (> 2 minutes), get a new one.
-  // If anything goes wrong, just stick with the old one and let it fail.
-  if (FUpdates.LastCheck < IncMinute(Now(), -2))
+  try
   {
-    try
+    bool Retried = false;
+    bool Retry;
+
+    do
     {
-      TUpdatesConfiguration Updates2 = FUpdates;
-      QueryUpdates(Updates2);
-      if (!Updates2.Results.DownloadUrl.IsEmpty())
+      Retry = false;
+      try
       {
-        FDownloadUrl = Updates2.Results.DownloadUrl;
+        FDownloaded = 0;
+
+        FHttp.reset(CreateHttp(FUpdates));
+        FHttp->URL = FUpdates.Results.DownloadUrl;
+        FHttp->OnDownload = HttpDownload;
+        FHttp->Get();
       }
-    }
-    catch (...)
-    {
-    }
-  }
+      catch (EAbort &)
+      {
+        throw;
+      }
+      catch (Exception & E)
+      {
+        // The original URL failed, try to get a fresh one and retry
+        if (!Retried)
+        {
+          try
+          {
+            // Check if new update data (URL particlarly) is available
+            if (QueryUpdates(FUpdates) &&
+                !FUpdates.Results.DownloadUrl.IsEmpty())
+            {
+              Retry = true;
+              Retried = true;
+            }
+          }
+          catch (...)
+          {
+          }
+        }
 
-  try
-  {
-    try
-    {
-      FHttp.reset(CreateHttp(FUpdates));
-      FHttp->URL = FDownloadUrl;
-      FHttp->OnDownload = HttpDownload;
-      FHttp->Get();
-    }
-    catch (EAbort &)
-    {
-      throw;
-    }
-    catch (Exception & E)
-    {
-      Configuration->Usage->Inc(L"UpdateFailuresDownload");
-      throw ExtException(&E, MainInstructions(LoadStr(UPDATE_DOWNLOAD_ERROR)));
+        if (!Retry)
+        {
+          Configuration->Usage->Inc(L"UpdateFailuresDownload");
+          throw ExtException(&E, MainInstructions(LoadStr(UPDATE_DOWNLOAD_ERROR)));
+        }
+      }
     }
+    while (Retry);
 
     Synchronize(UpdateDownloaded);
   }
@@ -1286,7 +1296,7 @@ void __fastcall TUpdateDownloadThread::UpdateDownloaded()
     DownloadNotVerified();
   }
 
-  UnicodeString FileName = FDownloadUrl;
+  UnicodeString FileName = FUpdates.Results.DownloadUrl;
   int P = FileName.Pos(L"?");
   if (P > 0)
   {