From 0a110a59d8a1cdb9c739d21f0b628f86196293d3 Mon Sep 17 00:00:00 2001
From: meiron03 <meiaaron99@gmail.com>
Date: Sat, 14 Oct 2023 15:01:19 -0400
Subject: [PATCH] Fix getAccessToken() race condition.

---
 .../pennapps/labs/pennmobile/MainActivity.kt  |  3 ++
 .../pennmobile/api/OAuth2NetworkManager.kt    | 43 +++++++++++++------
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/PennMobile/src/main/java/com/pennapps/labs/pennmobile/MainActivity.kt b/PennMobile/src/main/java/com/pennapps/labs/pennmobile/MainActivity.kt
index defd14e2..7736004d 100644
--- a/PennMobile/src/main/java/com/pennapps/labs/pennmobile/MainActivity.kt
+++ b/PennMobile/src/main/java/com/pennapps/labs/pennmobile/MainActivity.kt
@@ -48,6 +48,7 @@ import eightbitlab.com.blurview.RenderScriptBlur
 import kotlinx.android.synthetic.main.custom_sneaker_view.view.*
 import kotlinx.android.synthetic.main.fragment_dining_holder.*
 import kotlinx.android.synthetic.main.include_main.*
+import kotlinx.coroutines.sync.Mutex
 import retrofit.RestAdapter
 import retrofit.android.AndroidLog
 import retrofit.client.OkClient
@@ -60,6 +61,8 @@ class MainActivity : AppCompatActivity() {
     private lateinit var fragmentManager: FragmentManager
     private lateinit var mSharedPrefs: SharedPreferences
 
+    val tokenMutex = Mutex()
+
     override fun onCreate(savedInstanceState: Bundle?) {
         setTheme(R.style.AppTheme)
         if (Build.VERSION.SDK_INT > 28) {
diff --git a/PennMobile/src/main/java/com/pennapps/labs/pennmobile/api/OAuth2NetworkManager.kt b/PennMobile/src/main/java/com/pennapps/labs/pennmobile/api/OAuth2NetworkManager.kt
index ce3cb51d..55cca64e 100644
--- a/PennMobile/src/main/java/com/pennapps/labs/pennmobile/api/OAuth2NetworkManager.kt
+++ b/PennMobile/src/main/java/com/pennapps/labs/pennmobile/api/OAuth2NetworkManager.kt
@@ -3,10 +3,16 @@ package com.pennapps.labs.pennmobile.api
 import android.preference.PreferenceManager
 import android.provider.Settings
 import android.util.Log
+import androidx.lifecycle.lifecycleScope
 import com.pennapps.labs.pennmobile.BuildConfig
 import com.pennapps.labs.pennmobile.MainActivity
 import com.pennapps.labs.pennmobile.R
 import com.pennapps.labs.pennmobile.classes.AccessTokenResponse
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.sync.withLock
 import retrofit.Callback
 import retrofit.RetrofitError
 import retrofit.client.Response
@@ -25,24 +31,33 @@ class OAuth2NetworkManager(private var mActivity: MainActivity) {
 
     @Synchronized
     fun getAccessToken(function: () -> Unit) {
-        val expiresIn = sp.getString(mActivity.getString(R.string.expires_in), "")
-        if (expiresIn != "") {
-            val expiresAt = sp.getLong(mActivity.getString(R.string.token_expires_at), 0)
-            val currentTime = Calendar.getInstance().timeInMillis
-            if (currentTime >= expiresAt) { // if it has expired, refresh access token
-                Log.i("Accounts", "Expired")
-                refreshAccessToken(function)
+        mActivity.lifecycleScope.launch {
+            val tokenMutex = mActivity.tokenMutex
+            tokenMutex.lock()
+            val expiresIn = sp.getString(mActivity.getString(R.string.expires_in), "")
+            if (expiresIn != "") {
+                val expiresAt = sp.getLong(mActivity.getString(R.string.token_expires_at), 0)
+                val currentTime = Calendar.getInstance().timeInMillis
+                if (currentTime >= expiresAt) { // if it has expired, refresh access token
+                    Log.i("Accounts", "Expired")
+                    refreshAccessToken (function) {
+                        tokenMutex.unlock()
+                    }
+                } else {
+                    Log.i("Accounts", "Not Expired")
+                    tokenMutex.unlock()
+                    function.invoke()
+                }
             } else {
-                Log.i("Accounts", "Not Expired")
-                function.invoke()
+                refreshAccessToken (function) {
+                    tokenMutex.unlock()
+                }
             }
-        } else {
-            refreshAccessToken(function)
         }
     }
 
     @Synchronized
-    private fun refreshAccessToken(function: () -> Unit) {
+    private fun refreshAccessToken(function: () -> Unit, unlockMutex: () -> Unit) {
         val refreshToken = sp.getString(mActivity.getString(R.string.refresh_token), "")
         val clientID = BuildConfig.PLATFORM_CLIENT_ID
 
@@ -61,6 +76,7 @@ class OAuth2NetworkManager(private var mActivity: MainActivity) {
                         val currentTime = Calendar.getInstance().timeInMillis
                         editor.putLong(mActivity.getString(R.string.token_expires_at), currentTime + expiresInInt)
                         editor.apply()
+                        unlockMutex.invoke()
                         function.invoke()
                         Log.i("Accounts", "Reloaded Homepage")
                     }
@@ -72,9 +88,8 @@ class OAuth2NetworkManager(private var mActivity: MainActivity) {
 
                     if (error.response != null && error.response.status == 400) {
                         mActivity.startLoginFragment()
+                        unlockMutex.invoke()
                     }
-
-                    function.invoke()
                 }
             })
     }