fix: fix login to limited federation instance

Fixes #2146

src/routes/_actions/addInstance.js

@@ -37,8 +37,16 @@ async function redirectToOauth () {
   }
   const redirectUri = getRedirectUri()
   const registrationPromise = registerApplication(instanceNameInSearch, redirectUri)
-  const instanceInfo = await getInstanceInfo(instanceNameInSearch)
-  await database.setInstanceInfo(instanceNameInSearch, instanceInfo) // cache for later
+  try {
+    const instanceInfo = await getInstanceInfo(instanceNameInSearch)
+    await database.setInstanceInfo(instanceNameInSearch, instanceInfo) // cache for later
+  } catch (err) {
+    // We get a 401 in limited federation mode, so we can just skip setting the instance info in that case.
+    // It will be fetched automatically later.
+    if (err.status !== 401) {
+      throw err // this is a good way to test for typos in the instance name or some other problem
+    }
+  }
   const instanceData = await registrationPromise
   store.set({
     currentRegisteredInstanceName: instanceNameInSearch,

src/routes/_actions/instances.js

@@ -111,7 +111,11 @@ export async function updateVerifyCredentialsForCurrentInstance () {
 
 export async function updateInstanceInfo (instanceName) {
   await cacheFirstUpdateAfter(
-    () => getInstanceInfo(instanceName),
+    () => {
+      const { loggedInInstances } = store.get()
+      const accessToken = loggedInInstances[instanceName] && loggedInInstances[instanceName].access_token
+      return getInstanceInfo(instanceName, accessToken)
+    },
     () => database.getInstanceInfo(instanceName),
     info => database.setInstanceInfo(instanceName, info),
     info => {

src/routes/_api/instance.js

@@ -1,7 +1,9 @@
 import { get, DEFAULT_TIMEOUT } from '../_utils/ajax.js'
-import { basename } from './utils.js'
+import { auth, basename } from './utils.js'
 
-export function getInstanceInfo (instanceName) {
+export function getInstanceInfo (instanceName, accessToken) {
   const url = `${basename(instanceName)}/api/v1/instance`
-  return get(url, null, { timeout: DEFAULT_TIMEOUT })
+  // accessToken is required in limited federation mode, but elsewhere we don't need it (e.g. during login)
+  const headers = accessToken ? auth(accessToken) : null
+  return get(url, headers, { timeout: DEFAULT_TIMEOUT })
 }

src/routes/_pages/settings/instances/add.html

@@ -89,14 +89,16 @@
 
   export default {
     async oncreate () {
-      const codeMatch = location.search.match(/code=([^&]+)/)
-      if (codeMatch) {
-        return handleOauthCode(codeMatch[1])
+      const params = new URLSearchParams(location.search)
+      const code = params.get('code')
+      if (code) {
+        await handleOauthCode(code)
+      } else {
+        this.set({
+          hasIndexedDB: await testHasIndexedDB(),
+          hasLocalStorage: testHasLocalStorage()
+        })
       }
-      this.set({
-        hasIndexedDB: await testHasIndexedDB(),
-        hasLocalStorage: testHasLocalStorage()
-      })
     },
     components: {
       SettingsLayout,