Improve error UX around interception activation API

Author: pimterry

src/api/api-model.ts

@@ -189,16 +189,17 @@ export class ApiModel {
         } catch (err: any) {
             const activationError = err as ActivationError;
             activationDone = true;
+
             if (activationError.reportable !== false) {
                 addBreadcrumb(`Failed to activate ${id}`, { category: 'interceptor' });
-                logError(err);
+                throw err;
             }
+
+            // Non-reportable errors are friendly ones (like Global Chrome quit confirmation)
+            // that need to be returned nicely to the UI for further processing.
             return {
                 success: false,
-                metadata: activationError.metadata,
-                error: activationError.reportable !== false
-                    ? serializeError(activationError)
-                    : false
+                metadata: activationError.metadata
             };
         }
     }

src/api/rest-api.ts

@@ -89,12 +89,10 @@ export function exposeRestAPI(
         const interceptorOptions = req.body;
         const result = await apiModel.activateInterceptor(interceptorId, proxyPort, interceptorOptions);
 
-        if (result.success === true || result.error === false) {
-            // Some non-success is just temporary, e.g. global Chrome "exit running app please" confirmation.
-            res.json({ result });
-        } else {
-            res.status(500).json({ result });
-        }
+        // No thrown error here doesn't mean success: we have non-reportable failures for cases like
+        // Global Chrome "prompt to confirm quit" errors. We return those as 200 { success: false, metadata: ... }
+
+        res.json({ result });
     }));
 
     server.post('/client/send', handleErrors(async (req, res) => {

src/interceptors/frida/frida-android-integration.ts

@@ -130,7 +130,9 @@ export async function launchAndroidHost(adbClient: AdbClient, hostId: string) {
     const runAsRoot = await getRootCommand(deviceClient);
 
     if (!runAsRoot) {
-        throw new Error("Couldn't get root access to launch Frida Server");
+        throw new CustomError("Couldn't get root access to launch Frida Server", {
+            code: 'no-root'
+        });
     }
 
     const fridaServerStream = await deviceClient.shell(
@@ -151,7 +153,7 @@ export async function launchAndroidHost(adbClient: AdbClient, hostId: string) {
 
         return fridaServerStream;
     } catch (e: any) {
-        const errorMessage = e?.message === 'Wait loop failed'
+        const errorMessage = e?.code === 'wait-loop-failed'
             ? 'Frida server did not startup before timeout'
             : e.message ?? e;
         console.log('Fride launch failed:', errorMessage);
@@ -165,7 +167,7 @@ export async function launchAndroidHost(adbClient: AdbClient, hostId: string) {
             );
         });
 
-        throw new Error(`Failed to launch Frida server for ${hostId}: ${e.message ?? e}`);
+        throw new CustomError(errorMessage, { code: e?.code, cause: e });
     }
 }
 

src/interceptors/frida/frida-integration.ts

@@ -71,7 +71,9 @@ class FridaScriptError extends CustomError {
     constructor(
         message: FridaJs.ScriptAgentErrorMessage
     ) {
-        super(message.description);
+        super(message.description, {
+            code: 'frida-script-error'
+        });
         if (message.stack) {
             this.stack = message.stack;
         }
@@ -121,7 +123,7 @@ export async function testAndSelectProxyAddress(
                     if (message.payload.type === 'connected') {
                         resolve(message.payload.ip as string);
                     } else if (message.payload.type === 'connection-failed') {
-                        reject(new Error(`Could not connect to proxy on port ${proxyPort} at ${
+                        reject(new FridaProxyError(`Could not connect to proxy on port ${proxyPort} at ${
                             ips.length > 1
                             ? `any of: ${ips.join(', ')}`
                             : ips[0]
@@ -143,7 +145,12 @@ export async function testAndSelectProxyAddress(
             reject(e);
         }
     })).catch((e) => {
-        throw new FridaProxyError("No proxy IPs were reachable from the target", { cause: e });
+        if (e instanceof FridaProxyError) throw e;
+        else {
+            throw new FridaProxyError(`Proxy IP detection on target device failed for port ${proxyPort} and IPs ${
+                JSON.stringify(ips)
+            }`, { cause: e });
+        }
     });
 }
 

src/util/promise.ts

@@ -13,7 +13,11 @@ export async function waitUntil<T extends unknown>(
         result = await test();
     }
 
-    if (!result) throw new Error(`Wait loop failed`);
+    if (!result) {
+        throw new CustomError(`Wait loop failed after ${tries} retries`, {
+            code: 'wait-loop-failed'
+        });
+    }
     else return result as Exclude<T, false>;
 }