Revert "Networkstack: drop own implementation of DNS-Server selection"

This reverts commit 3bbdd69d620055a88f42bc62e10421e250a57d9e.

3 files changed, 186 insertions, 0 deletions

diff --git a/src/main/java/de/pixart/messenger/utils/AndroidUsingExecLowPriority.java b/src/main/java/de/pixart/messenger/utils/AndroidUsingExecLowPriority.java
new file mode 100644
index 000000000..6097fcd03
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/utils/AndroidUsingExecLowPriority.java
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2015-2016 the original author or authors
+ *
+ * This software is licensed under the Apache License, Version 2.0,
+ * the GNU Lesser General Public License version 2 or later ("LGPL")
+ * and the WTFPL.
+ * You may choose either license to govern your use of this software only
+ * upon the condition that you accept all of the terms of either
+ * the Apache License 2.0, the LGPL 2.1+ or the WTFPL.
+ */
+
+package de.pixart.messenger.utils;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.LineNumberReader;
+import java.net.InetAddress;
+import java.util.HashSet;
+import java.util.logging.Level;
+
+import de.measite.minidns.dnsserverlookup.AbstractDNSServerLookupMechanism;
+import de.measite.minidns.dnsserverlookup.AndroidUsingReflection;
+import de.measite.minidns.dnsserverlookup.DNSServerLookupMechanism;
+import de.measite.minidns.util.PlatformDetection;
+
+/**
+ * Try to retrieve the list of DNS server by executing getprop.
+ */
+public class AndroidUsingExecLowPriority extends AbstractDNSServerLookupMechanism {
+
+    public static final DNSServerLookupMechanism INSTANCE = new AndroidUsingExecLowPriority();
+    public static final int PRIORITY = AndroidUsingReflection.PRIORITY + 1;
+
+    private AndroidUsingExecLowPriority() {
+        super(AndroidUsingExecLowPriority.class.getSimpleName(), PRIORITY);
+    }
+
+    @Override
+    public String[] getDnsServerAddresses() {
+        try {
+            Process process = Runtime.getRuntime().exec("getprop");
+            InputStream inputStream = process.getInputStream();
+            LineNumberReader lnr = new LineNumberReader(
+                    new InputStreamReader(inputStream));
+            String line;
+            HashSet<String> server = new HashSet<>(6);
+            while ((line = lnr.readLine()) != null) {
+                int split = line.indexOf("]: [");
+                if (split == -1) {
+                    continue;
+                }
+                String property = line.substring(1, split);
+                String value = line.substring(split + 4, line.length() - 1);
+
+                if (value.isEmpty()) {
+                    continue;
+                }
+
+                if (property.endsWith(".dns") || property.endsWith(".dns1") ||
+                        property.endsWith(".dns2") || property.endsWith(".dns3") ||
+                        property.endsWith(".dns4")) {
+
+                    // normalize the address
+
+                    InetAddress ip = InetAddress.getByName(value);
+
+                    if (ip == null) continue;
+
+                    value = ip.getHostAddress();
+
+                    if (value == null) continue;
+                    if (value.length() == 0) continue;
+
+                    server.add(value);
+                }
+            }
+            if (server.size() > 0) {
+                return server.toArray(new String[server.size()]);
+            }
+        } catch (IOException e) {
+            LOGGER.log(Level.WARNING, "Exception in findDNSByExec", e);
+        }
+        return null;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return PlatformDetection.isAndroid();
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/utils/AndroidUsingLinkProperties.java b/src/main/java/de/pixart/messenger/utils/AndroidUsingLinkProperties.java
new file mode 100644
index 000000000..f2f33dc1b
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/utils/AndroidUsingLinkProperties.java
@@ -0,0 +1,90 @@
+package de.pixart.messenger.utils;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.NetworkInfo;
+import android.net.RouteInfo;
+import android.os.Build;
+
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.List;
+
+import de.measite.minidns.dnsserverlookup.AbstractDNSServerLookupMechanism;
+import de.measite.minidns.dnsserverlookup.AndroidUsingExec;
+
+public class AndroidUsingLinkProperties extends AbstractDNSServerLookupMechanism {
+
+    private final Context context;
+
+    AndroidUsingLinkProperties(Context context) {
+        super(AndroidUsingLinkProperties.class.getSimpleName(), AndroidUsingExec.PRIORITY - 1);
+        this.context = context;
+    }
+
+    @Override
+    public boolean isAvailable() {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP;
+    }
+
+    @Override
+    @TargetApi(21)
+    public String[] getDnsServerAddresses() {
+        final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+        final Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks();
+        if (networks == null) {
+            return new String[0];
+        }
+        final Network activeNetwork = getActiveNetwork(connectivityManager);
+        final List<String> servers = new ArrayList<>();
+        int vpnOffset = 0;
+        for (Network network : networks) {
+            LinkProperties linkProperties = connectivityManager.getLinkProperties(network);
+            if (linkProperties == null) {
+                continue;
+            }
+            final NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);
+            final boolean isActiveNetwork = network.equals(activeNetwork);
+            final boolean isVpn = networkInfo != null && networkInfo.getType() == ConnectivityManager.TYPE_VPN;
+            if (isActiveNetwork && isVpn) {
+                final List<String> tmp = getIPv4First(linkProperties.getDnsServers());
+                servers.addAll(0, tmp);
+                vpnOffset += tmp.size();
+            } else if (hasDefaultRoute(linkProperties) || isActiveNetwork || activeNetwork == null || isVpn) {
+                servers.addAll(vpnOffset, getIPv4First(linkProperties.getDnsServers()));
+            }
+        }
+        return servers.toArray(new String[0]);
+    }
+
+    @TargetApi(23)
+    private static Network getActiveNetwork(ConnectivityManager cm) {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? cm.getActiveNetwork() : null;
+    }
+
+    private static List<String> getIPv4First(List<InetAddress> in) {
+        List<String> out = new ArrayList<>();
+        for (InetAddress address : in) {
+            if (address instanceof Inet4Address) {
+                out.add(0, address.getHostAddress());
+            } else {
+                out.add(address.getHostAddress());
+            }
+        }
+        return out;
+    }
+
+    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+    private static boolean hasDefaultRoute(LinkProperties linkProperties) {
+        for (RouteInfo route : linkProperties.getRoutes()) {
+            if (route.isDefaultRoute()) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/utils/Resolver.java b/src/main/java/de/pixart/messenger/utils/Resolver.java
index 250a6f097..e2cec35fe 100644
--- a/src/main/java/de/pixart/messenger/utils/Resolver.java
+++ b/src/main/java/de/pixart/messenger/utils/Resolver.java
@@ -29,6 +29,7 @@ import de.measite.minidns.DNSName;
 import de.measite.minidns.Question;
 import de.measite.minidns.Record;
 import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException;
+import de.measite.minidns.dnsserverlookup.AndroidUsingExec;
 import de.measite.minidns.hla.DnssecResolverApi;
 import de.measite.minidns.hla.ResolverApi;
 import de.measite.minidns.hla.ResolverResult;
@@ -56,6 +57,9 @@ public class Resolver {
 
     public static void init(XmppConnectionService service) {
         Resolver.SERVICE = service;
+        DNSClient.removeDNSServerLookupMechanism(AndroidUsingExec.INSTANCE);
+        DNSClient.addDnsServerLookupMechanism(AndroidUsingExecLowPriority.INSTANCE);
+        DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(service));
         final AbstractDNSClient client = ResolverApi.INSTANCE.getClient();
         if (client instanceof ReliableDNSClient) {
             disableHardcodedDnsServers((ReliableDNSClient) client);