Fixed an issue on Android < Q where if the user already successfully connected to the network before, a new connection request with a wrong password would succeed. (Tested on Android 8.1 OnePlus 5T)

Changed the WIFI behavior when disconnecting from an app-created network on Android < Q to be loosely similar to observed behvaior on Android 11 (OnePlus 7 Pro) where the device will try to reconnect to the previously connected network.

Author: KhatibFX

packages/wifi_iot/android/src/main/java/com/alternadom/wifiiot/WifiIotPlugin.java

@@ -14,7 +14,6 @@
 import android.net.NetworkRequest;
 import android.net.wifi.ScanResult;
 import android.net.wifi.SoftApConfiguration;
-import android.net.wifi.SupplicantState;
 import android.net.wifi.WifiConfiguration;
 import android.net.wifi.WifiInfo;
 import android.net.wifi.WifiManager;
@@ -49,6 +48,8 @@
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
+import java.util.Random;
+import android.net.wifi.SupplicantState;
 
 /** WifiIotPlugin */
 public class WifiIotPlugin
@@ -73,6 +74,8 @@ public class WifiIotPlugin
   private List<WifiNetworkSuggestion> networkSuggestions;
   private List<String> ssidsToBeRemovedOnExit = new ArrayList<String>();
   private List<WifiNetworkSuggestion> suggestionsToBeRemovedOnExit = new ArrayList<>();
+  //last connected network ID from outside the app
+  private int lastConnectedNetworkId = -1;
 
   // Permission request management
   private boolean requestingPermission = false;
@@ -98,20 +101,12 @@ private void initWithActivity(Activity activity) {
 
   // cleanup
   private void cleanup() {
-    if (!ssidsToBeRemovedOnExit.isEmpty()) {
-      List<WifiConfiguration> wifiConfigList = moWiFi.getConfiguredNetworks();
-      for (String ssid : ssidsToBeRemovedOnExit) {
-        for (WifiConfiguration wifiConfig : wifiConfigList) {
-          if (wifiConfig.SSID.equals(ssid)) {
-            moWiFi.removeNetwork(wifiConfig.networkId);
-          }
-        }
-      }
-    }
+    removeAddedNetworks();
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q && !suggestionsToBeRemovedOnExit.isEmpty()) {
       moWiFi.removeNetworkSuggestions(suggestionsToBeRemovedOnExit);
     }
     // setting all members to null to avoid memory leaks
+    lastConnectedNetworkId = -1;
     channel = null;
     eventChannel = null;
     moActivity = null;
@@ -120,6 +115,20 @@ private void cleanup() {
     moWiFiAPManager = null;
   }
 
+  private void removeAddedNetworks() {
+    if (!ssidsToBeRemovedOnExit.isEmpty()) {
+      List<WifiConfiguration> wifiConfigList = moWiFi.getConfiguredNetworks();
+      for (String ssid : ssidsToBeRemovedOnExit) {
+        for (WifiConfiguration wifiConfig : wifiConfigList) {
+          if (wifiConfig.SSID.equals(ssid)) {
+            moWiFi.removeNetwork(wifiConfig.networkId);
+          }
+        }
+      }
+    }
+    ssidsToBeRemovedOnExit.clear();
+  }
+
   /** Plugin registration. This is used for registering with v1 Android embedding. */
   public static void registerWith(Registrar registrar) {
     final MethodChannel channel = new MethodChannel(registrar.messenger(), "wifi_iot");
@@ -968,7 +977,7 @@ private void registerWifiNetwork(final MethodCall poCall, final Result poResult)
       android.net.wifi.WifiConfiguration conf =
           generateConfiguration(ssid, bssid, password, security, isHidden);
 
-      int updateNetwork = registerWifiNetworkDeprecated(conf);
+      int updateNetwork = registerWifiNetworkDeprecated(conf, false);
 
       if (updateNetwork == -1) {
         poResult.error("Error", "Error updating network configuration", "");
@@ -1107,6 +1116,10 @@ private void disconnect(Result poResult) {
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
       //noinspection deprecation
       disconnected = moWiFi.disconnect();
+      if(lastConnectedNetworkId != -1) {
+        //android 8.1 won't automatically reconnect to the previous network if it shares the same SSID
+        moWiFi.enableNetwork(lastConnectedNetworkId, true);
+      }
     } else {
       if (networkCallback != null) {
         final ConnectivityManager connectivityManager =
@@ -1186,14 +1199,24 @@ private void removeWifiNetwork(MethodCall poCall, Result poResult) {
     if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
       List<android.net.wifi.WifiConfiguration> mWifiConfigList = moWiFi.getConfiguredNetworks();
       for (android.net.wifi.WifiConfiguration wifiConfig : mWifiConfigList) {
-        String comparableSSID = ('"' + prefix_ssid); //Add quotes because wifiConfig.SSID has them
-        if (wifiConfig.SSID.startsWith(comparableSSID)) {
-          moWiFi.removeNetwork(wifiConfig.networkId);
-          moWiFi.saveConfiguration();
-          removed = true;
-          break;
+        String comparableSSID = ('"' + prefix_ssid + '"'); //Add quotes because wifiConfig.SSID has them
+        if (wifiConfig.SSID.equals(comparableSSID)) {
+          Boolean isRemoved = moWiFi.removeNetwork(wifiConfig.networkId);
+          if(isRemoved) {
+            moWiFi.saveConfiguration();
+            removed = true;
+            //if the last connected network was our app's network, reset the last connected network
+            if(wifiConfig.networkId == lastConnectedNetworkId) {
+              lastConnectedNetworkId = -1;
+            }
+          }
+          //multiple networks with the same SSID could be removed
         }
       }
+      if(lastConnectedNetworkId != -1) {
+        //android 8.1 won't automatically reconnect to the previous network if it shares the same SSID
+        moWiFi.enableNetwork(lastConnectedNetworkId, true);
+      }
     }
 
     // remove network suggestion
@@ -1399,7 +1422,7 @@ public void onUnavailable() {
   }
 
   @SuppressWarnings("deprecation")
-  private int registerWifiNetworkDeprecated(android.net.wifi.WifiConfiguration conf) {
+  private int registerWifiNetworkDeprecated(android.net.wifi.WifiConfiguration conf, Boolean joinOnce) {
     int updateNetwork = -1;
     int registeredNetwork = -1;
 
@@ -1414,14 +1437,51 @@ private int registerWifiNetworkDeprecated(android.net.wifi.WifiConfiguration con
                 || wifiConfig.BSSID.equals(conf.BSSID))) {
           conf.networkId = wifiConfig.networkId;
           registeredNetwork = wifiConfig.networkId;
-          updateNetwork = moWiFi.updateNetwork(conf);
+          //only try to update the configuration if joinOnce is false
+          //otherwise use the new add/update method
+          if(joinOnce == false) {
+            updateNetwork = moWiFi.updateNetwork(conf);
+            //required for pre API 26
+            moWiFi.saveConfiguration();
+          }
+          //Android 6.0 and higher no longer allows you to update a network that wasn't created
+          //from our app, nor delete it, nor add a network with the same SSID
+          //See https://developer.android.com/about/versions/marshmallow/android-6.0-changes.html#behavior-network
+          if(updateNetwork == -1) {
+            //we add some random number to the conf SSID, add that network, then change the SSID
+            // back to circumvent the issue
+            String ssid = conf.SSID;
+            Random random = new Random(System.currentTimeMillis());
+            //loop in the rare case that the generated ssid already exists
+            for (int i = 0; i < 20; i++) {
+              int randomInteger = random.nextInt(10000);
+              //create a valid SSID with max length of 32
+              String ssidRandomized = ssid+randomInteger;
+              int ssidRandomizedExtraLength = ssidRandomized.length()-32;
+              if(ssidRandomizedExtraLength > 0) {
+                ssidRandomized = ssid.substring(0,ssid.length()-ssidRandomizedExtraLength)+randomInteger;
+              }
+              conf.SSID = "\"" + ssidRandomized + "\"";
+              updateNetwork = moWiFi.addNetwork(conf); // Add my wifi with another name
+              conf.SSID = ssid;
+              conf.networkId = updateNetwork;
+              updateNetwork = moWiFi.updateNetwork(conf); // After my wifi is added with another name, I change it to the desired name
+              moWiFi.saveConfiguration();
+              if(updateNetwork != -1) {
+                break;
+              }
+            }
+          }
+          //no need to continue looping
+          break;
         }
       }
     }
 
     /// If network not already in configured networks add new network
     if (updateNetwork == -1) {
       updateNetwork = moWiFi.addNetwork(conf);
+      conf.networkId = updateNetwork;
       moWiFi.saveConfiguration();
     }
 
@@ -1491,7 +1551,7 @@ private Boolean connectToDeprecated(
     android.net.wifi.WifiConfiguration conf =
         generateConfiguration(ssid, bssid, password, security, isHidden);
 
-    int updateNetwork = registerWifiNetworkDeprecated(conf);
+    int updateNetwork = registerWifiNetworkDeprecated(conf, joinOnce);
 
     if (updateNetwork == -1) {
       return false;
@@ -1500,6 +1560,9 @@ private Boolean connectToDeprecated(
     if (joinOnce != null && joinOnce.booleanValue()) {
       ssidsToBeRemovedOnExit.add(conf.SSID);
     }
+    if(lastConnectedNetworkId == -1) {
+      lastConnectedNetworkId = moWiFi.getConnectionInfo().getNetworkId();
+    }
 
     boolean disconnect = moWiFi.disconnect();
     if (!disconnect) {
@@ -1510,24 +1573,38 @@ private Boolean connectToDeprecated(
     if (!enabled) return false;
 
     boolean connected = false;
+    int networkId = -1;
     for (int i = 0; i < 20; i++) {
       WifiInfo currentNet = moWiFi.getConnectionInfo();
-      int networkId = currentNet.getNetworkId();
+      networkId = currentNet.getNetworkId();
       SupplicantState netState = currentNet.getSupplicantState();
 
       // Wait for connection to reach state completed
       // to discard false positives like auth error
       if (networkId != -1 && netState == SupplicantState.COMPLETED) {
         connected = networkId == updateNetwork;
-        break;
+        if(connected == true) {
+          break;
+        } else {
+          disconnect = moWiFi.disconnect();
+          if (!disconnect) {
+            break;
+          }
+
+          enabled = moWiFi.enableNetwork(updateNetwork, true);
+          break;
+        }
       }
       try {
-        Thread.sleep(500);
+        Thread.sleep(1000);
       } catch (InterruptedException ignored) {
         break;
       }
     }
-
+    if(!connected && lastConnectedNetworkId != -1) {
+      //android 8.1 won't automatically reconnect to the previous network if it shares the same SSID
+      moWiFi.enableNetwork(lastConnectedNetworkId, true);
+    }
     return connected;
   }
 }