From 1d8fa7e99dc1304ece611bff99d12f52981ab1f9 Mon Sep 17 00:00:00 2001
From: Christian Schneppe <christian@pix-art.de>
Date: Tue, 25 Jun 2019 21:17:32 +0200
Subject: Revert "Networkstack - let OS decide IPv4 or IPv6 (#267)"

This reverts commit e6a15597904019f68c02e6fd8f61fb6de0b13324.

If there is IPv6 available but the server doesn't listen to it, the connection will not be established
---
 .../utils/AndroidUsingExecLowPriority.java         | 92 ++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 src/main/java/de/pixart/messenger/utils/AndroidUsingExecLowPriority.java

(limited to 'src/main/java/de/pixart/messenger/utils/AndroidUsingExecLowPriority.java')

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
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