fix: Prevent empty stack trace

Author: timokoessler

library/helpers/cleanupStackTrace.test.ts

@@ -131,3 +131,45 @@ Error
 
   t.same(cleaned, expected);
 });
+
+t.test(
+  "it does not remove the complete stack trace if the library root is wrong",
+  async () => {
+    const stack = `
+Error
+    at Collection.wrap (/Users/hansott/Code/node-RASP/build/agent/applyHooks.js:149:33)
+    at Posts.all (/Users/hansott/Code/node-RASP/sample-apps/express-mongodb/posts.js:30:36)
+    at /Users/hansott/Code/node-RASP/sample-apps/express-mongodb/app.js:49:41
+    at asyncUtilWrap (/Users/hansott/Code/node-RASP/node_modules/express-async-handler/index.js:3:20)
+    at /Users/hansott/Code/node-RASP/build/sources/express/wrapRequestHandler.js:22:20
+    at runWithContext (/Users/hansott/Code/node-RASP/build/agent/Context.js:34:16)
+    at /Users/hansott/Code/node-RASP/build/sources/express/wrapRequestHandler.js:12:45
+    at Layer.handle [as handle_request] (/Users/hansott/Code/node-RASP/node_modules/express/lib/router/layer.js:95:5)
+    at next (/Users/hansott/Code/node-RASP/node_modules/express/lib/router/route.js:149:13)
+    at Route.dispatch (/Users/hansott/Code/node-RASP/node_modules/express/lib/router/route.js:119:3)
+`.trim();
+
+    const cleaned = cleanupStackTrace(stack, "/Users/hansott/Code/node-RASP/");
+
+    const expected = `
+Error
+    at Collection.wrap (/Users/hansott/Code/node-RASP/build/agent/applyHooks.js:149:33)
+    at Posts.all (/Users/hansott/Code/node-RASP/sample-apps/express-mongodb/posts.js:30:36)
+    at /Users/hansott/Code/node-RASP/sample-apps/express-mongodb/app.js:49:41
+    at asyncUtilWrap (/Users/hansott/Code/node-RASP/node_modules/express-async-handler/index.js:3:20)
+    at /Users/hansott/Code/node-RASP/build/sources/express/wrapRequestHandler.js:22:20
+    at runWithContext (/Users/hansott/Code/node-RASP/build/agent/Context.js:34:16)
+    at /Users/hansott/Code/node-RASP/build/sources/express/wrapRequestHandler.js:12:45
+    at Layer.handle [as handle_request] (/Users/hansott/Code/node-RASP/node_modules/express/lib/router/layer.js:95:5)
+    at next (/Users/hansott/Code/node-RASP/node_modules/express/lib/router/route.js:149:13)
+    at Route.dispatch (/Users/hansott/Code/node-RASP/node_modules/express/lib/router/route.js:119:3)
+`.trim();
+
+    t.same(cleaned, expected);
+  }
+);
+
+t.test("it catches exceptions", async (t) => {
+  // @ts-expect-error Test with invalid input
+  t.same(cleanupStackTrace("test", undefined), "test");
+});

library/helpers/cleanupStackTrace.ts

@@ -2,12 +2,18 @@ import { escapeStringRegexp } from "./escapeStringRegexp";
 
 export function cleanupStackTrace(stack: string, libraryRoot: string): string {
   try {
-    return stack
+    const newStackLines = stack
       .split("\n")
       .filter(createLineFilter(libraryRoot))
-      .map(createLineMapper(libraryRoot))
-      .join("\n")
-      .trim();
+      .map(createLineMapper(libraryRoot));
+
+    // If the stack only has one line (the error message), we return the original stack trace.
+    // This could happen if the detected library root is wrong
+    if (newStackLines.length <= 1) {
+      return stack;
+    }
+
+    return newStackLines.join("\n").trim();
   } catch {
     // Safer to return the original stack trace in case of an error
     // than to crash the application