From b9c247e2b12660dd0c38def9ba00141930b0e7d1 Mon Sep 17 00:00:00 2001
From: Hans-Christoph Steiner <hans@eds.org>
Date: Wed, 18 Apr 2018 10:50:09 +0200
Subject: [PATCH] if WifiManager fails to return netmask, directly query net
 interfaces

Google broke returning the netmask somewhere around android-21. This could
be done using more official APIs, but this reuses stuff that needs to be
there anyway.

closes #577
https://code.google.com/p/android/issues/detail?id=82477#c5
https://issuetracker.google.com/issues/37015180
---
 app/src/main/java/org/fdroid/fdroid/FDroidApp.java |  4 +++-
 .../fdroid/fdroid/net/WifiStateChangeService.java  | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/app/src/main/java/org/fdroid/fdroid/FDroidApp.java b/app/src/main/java/org/fdroid/fdroid/FDroidApp.java
index d6321dfbb..c68f6737c 100644
--- a/app/src/main/java/org/fdroid/fdroid/FDroidApp.java
+++ b/app/src/main/java/org/fdroid/fdroid/FDroidApp.java
@@ -114,6 +114,8 @@ public class FDroidApp extends Application {
 
     public static volatile int networkState = ConnectivityMonitorService.FLAG_NET_UNAVAILABLE;
 
+    public static final SubnetUtils.SubnetInfo UNSET_SUBNET_INFO = new SubnetUtils("0.0.0.0/32").getInfo();
+
     private static volatile LongSparseArray<String> lastWorkingMirrorArray = new LongSparseArray<>(1);
     private static volatile int numTries = Integer.MAX_VALUE;
     private static volatile int timeout = 10000;
@@ -231,7 +233,7 @@ public class FDroidApp extends Application {
     public static void initWifiSettings() {
         port = 8888;
         ipAddressString = null;
-        subnetInfo = new SubnetUtils("0.0.0.0/32").getInfo();
+        subnetInfo = UNSET_SUBNET_INFO;
         ssid = "";
         bssid = "";
         repo = new Repo();
diff --git a/app/src/main/java/org/fdroid/fdroid/net/WifiStateChangeService.java b/app/src/main/java/org/fdroid/fdroid/net/WifiStateChangeService.java
index fcd62ad6c..d91100ea4 100644
--- a/app/src/main/java/org/fdroid/fdroid/net/WifiStateChangeService.java
+++ b/app/src/main/java/org/fdroid/fdroid/net/WifiStateChangeService.java
@@ -121,6 +121,10 @@ public class WifiStateChangeService extends IntentService {
                                 }
                             }
                         }
+                        if (FDroidApp.ipAddressString == null
+                                || FDroidApp.subnetInfo == FDroidApp.UNSET_SUBNET_INFO) {
+                            setIpInfoFromNetworkInterface();
+                        }
                     } else if (wifiState == WifiManager.WIFI_STATE_DISABLED
                             || wifiState == WifiManager.WIFI_STATE_DISABLING) {
                         // try once to see if its a hotspot
@@ -210,6 +214,16 @@ public class WifiStateChangeService extends IntentService {
         }
     }
 
+    /**
+     * Search for known Wi-Fi, Hotspot, and local network interfaces and get
+     * the IP Address info from it.  This is necessary because network
+     * interfaces in Hotspot/AP mode do not show up in the regular
+     * {@link WifiManager} queries, and also on
+     * {@link android.os.Build.VERSION_CODES#LOLLIPOP Android 5.0} and newer,
+     * {@link WifiManager#getDhcpInfo()} returns an invalid netmask.
+     *
+     * @see <a href="https://issuetracker.google.com/issues/37015180">netmask of WifiManager.getDhcpInfo() is always zero on Android 5.0</a>
+     */
     private void setIpInfoFromNetworkInterface() {
         try {
             Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();