Verify server certificates before returning existing token

Summary:
If the server certificates have expired, then the returned token will no longer be valid as soon as the certificates are renewed.

So, validate this before returning any existing token.

This was not an issue before, as launching used to be the last step during bootstrapping.

Reviewed By: antonk52

Differential Revision: D48902334

fbshipit-source-id: 2458aa0df806db245994ee742f42bff47a533e23

desktop/flipper-server-core/src/app-connectivity/certificate-exchange/certificate-utils.tsx

@@ -168,6 +168,7 @@ const ensureServerCertExists = async (): Promise<void> => {
   } catch (e) {
     console.warn('Not all certs are valid, generating new ones', e);
     await generateServerCertificate();
+    await generateAuthToken();
   }
 };
 
@@ -317,6 +318,12 @@ export const generateAuthToken = async () => {
 };
 
 export const getAuthToken = async (): Promise<string> => {
+  // Ensure we check for the validity of certificates before
+  // returning an authentication token.
+  // If the server certificates have expired, they will need
+  // to be renewed and will invalidate any existing token.
+  await ensureServerCertExists();
+
   if (!(await hasAuthToken())) {
     return generateAuthToken();
   }