New config option cwmp.downloadSuccessOnTimeout

Workaround for CPEs that neglect to send TransferComplete message after
a successful download.

lib/session.ts

@@ -458,7 +458,36 @@ export async function timeoutOperations(
         (e) => configContextCallback(sessionContext, e)
       ) * 1000;
 
-    if (sessionContext.timestamp > operation.timestamp + DOWNLOAD_TIMEOUT) {
+    if (sessionContext.timestamp < operation.timestamp + DOWNLOAD_TIMEOUT)
+      continue;
+
+    logger.accessWarn({
+      sessionContext: sessionContext,
+      message: "Download operation timed out",
+      commandKey: commandKey,
+    });
+
+    const SUCCESS_ON_TIMEOUT = +localCache.getConfig(
+      sessionContext.cacheSnapshot,
+      "cwmp.downloadSuccessOnTimeout",
+      {},
+      sessionContext.timestamp,
+      (e) => configContextCallback(sessionContext, e)
+    );
+
+    if (SUCCESS_ON_TIMEOUT) {
+      const r = {
+        name: "TransferComplete" as const,
+        commandKey: commandKey,
+        startTime: 0,
+        completeTime: 0,
+      };
+
+      // Call transferComplete code and ignore the response
+      await transferComplete(sessionContext, r);
+      continue;
+    }
+
     delete sessionContext.operations[commandKey];
     if (!sessionContext.operationsTouched)
       sessionContext.operationsTouched = {};
@@ -474,7 +503,6 @@ export async function timeoutOperations(
 
     revertDownloadParameters(sessionContext, operation.args.instance);
   }
-  }
 
   return { faults, operations };
 }