Implement full auth flow in iOS

README.md

@@ -10,6 +10,11 @@ Uses:
 - [MobX](https://mobx.js.org/README.html) and [MobX State Tree](https://mobx-state-tree.js.org/)
 - [Async Storage](https://github.com/react-native-async-storage/async-storage)
 
+## TODOs
+
+- Handle the "unauthed" state better than changing route definitions
+  - Currently it's possible to get a 404 if the auth state changes
+
 ## Build instructions
 
 - Setup your environment [using the react native instructions](https://reactnative.dev/docs/environment-setup).
@@ -55,4 +60,8 @@ For native builds, we must provide a polyfill of `webcrypto`. We use [react-nati
 `./platform/polyfills.*.ts` adds polyfills to the environment. Currently this includes:
 
 - webcrypto
-- TextEncoder / TextDecoder
+- TextEncoder / TextDecoder
+
+### Auth flow
+
+The auth flow is based on a browser app which is specified by the `REACT_APP_AUTH_LOBBY` env var. The app redirects to that location with the UCAN request, and then waits for a redirect back. In the native platforms with proper support, it will do this using an in-app browser. In native without in-app browser, or in the Web platform, it will handle this with redirects. The ucan is extracted from the hash fragment of the "return url" which is provided either by the in-app browser in response or detected during initial setup in the case of redirects.

src/platform/urls.tsx

@@ -1,4 +1,5 @@
-import {isIOS, isAndroid} from './detection'
+import {Linking} from 'react-native'
+import {isIOS, isAndroid, isNative, isWeb} from './detection'
 
 export function makeAppUrl(path = '') {
   if (isIOS) {
@@ -10,3 +11,27 @@ export function makeAppUrl(path = '') {
     return `${window.location.origin}${path}`
   }
 }
+
+export function extractHashFragment(url: string): string {
+  return url.split('#')[1] || ''
+}
+
+export async function getInitialURL(): Promise<string> {
+  if (isNative) {
+    const url = await Linking.getInitialURL()
+    if (url) {
+      return url
+    }
+    return makeAppUrl()
+  } else {
+    // @ts-ignore window exists -prf
+    return window.location.toString()
+  }
+}
+
+export function clearHash() {
+  if (isWeb) {
+    // @ts-ignore window exists -prf
+    window.location.hash = ''
+  }
+}

src/state/auth.ts

@@ -3,7 +3,12 @@ import * as auth from '@adxp/auth'
 import * as ucan from 'ucans'
 import {InAppBrowser} from 'react-native-inappbrowser-reborn'
 import {isWeb} from '../platform/detection'
-import {makeAppUrl} from '../platform/urls'
+import {
+  getInitialURL,
+  extractHashFragment,
+  clearHash,
+  makeAppUrl,
+} from '../platform/urls'
 import * as storage from './storage'
 import * as env from '../env'
 
@@ -20,26 +25,28 @@ export async function logout(authStore: ReactNativeStore) {
   await authStore.reset()
 }
 
-export async function parseUrlForUcan() {
-  if (isWeb) {
-    // @ts-ignore window is defined -prf
-    const fragment = window.location.hash
-    if (fragment.length < 1) {
-      return undefined
-    }
-    try {
-      const ucan = await auth.parseLobbyResponseHashFragment(fragment)
-      // @ts-ignore window is defined -prf
-      window.location.hash = ''
-      return ucan
-    } catch (err) {
-      return undefined
-    }
-  } else {
-    // TODO
+export async function parseUrlForUcan(fragment: string) {
+  try {
+    return await auth.parseLobbyResponseHashFragment(fragment)
+  } catch (err) {
+    return undefined
   }
 }
 
+export async function initialLoadUcanCheck(authStore: ReactNativeStore) {
+  let wasAuthed = false
+  const fragment = extractHashFragment(await getInitialURL())
+  if (fragment) {
+    const ucan = await parseUrlForUcan(fragment)
+    if (ucan) {
+      await authStore.addUcan(ucan)
+      wasAuthed = true
+      clearHash()
+    }
+  }
+  return wasAuthed
+}
+
 export async function requestAppUcan(authStore: ReactNativeStore) {
   const did = await authStore.getDid()
   const returnUrl = makeAppUrl()
@@ -53,6 +60,7 @@ export async function requestAppUcan(authStore: ReactNativeStore) {
   }
 
   if (await InAppBrowser.isAvailable()) {
+    // use in-app browser
     const res = await InAppBrowser.openAuth(url, returnUrl, {
       // iOS Properties
       ephemeralWebSession: false,
@@ -62,12 +70,20 @@ export async function requestAppUcan(authStore: ReactNativeStore) {
       enableDefaultShare: false,
     })
     if (res.type === 'success' && res.url) {
-      Linking.openURL(res.url)
+      const fragment = extractHashFragment(res.url)
+      if (fragment) {
+        const ucan = await parseUrlForUcan(fragment)
+        if (ucan) {
+          await authStore.addUcan(ucan)
+          return true
+        }
+      }
     } else {
-      console.error('Bad response', res)
+      console.log('Not completed', res)
       return false
     }
   } else {
+    // use system browser
     Linking.openURL(url)
   }
   return true

src/state/index.ts

@@ -7,6 +7,7 @@ import {
 import {Environment} from './env'
 import * as storage from './storage'
 import * as auth from './auth'
+import * as urls from '../platform/urls'
 
 const ROOT_STATE_STORAGE_KEY = 'root'
 
@@ -32,9 +33,9 @@ export async function setupState() {
   if (env.authStore) {
     const isAuthed = await auth.isAuthed(env.authStore)
     rootStore.session.setAuthed(isAuthed)
-    const ucan = await auth.parseUrlForUcan()
-    if (ucan) {
-      await env.authStore.addUcan(ucan)
+
+    // handle redirect from auth
+    if (await auth.initialLoadUcanCheck(env.authStore)) {
       rootStore.session.setAuthed(true)
     }
   }