1 files changed, 165 insertions, 0 deletions
diff --git a/src/main/java/de/thedevstack/conversationsplus/utils/DNSHelper.java b/src/main/java/de/thedevstack/conversationsplus/utils/DNSHelper.java
new file mode 100644
index 00000000..a0fd9995
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/utils/DNSHelper.java
@@ -0,0 +1,165 @@
+package de.thedevstack.conversationsplus.utils;
+
+import android.annotation.TargetApi;
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.LinkProperties;
+import android.net.Network;
+import android.net.RouteInfo;
+import android.os.Build;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.TreeSet;
+import java.util.regex.Pattern;
+
+import de.measite.minidns.Client;
+import de.measite.minidns.DNSMessage;
+import de.measite.minidns.Record;
+import de.measite.minidns.Record.CLASS;
+import de.measite.minidns.Record.TYPE;
+import de.measite.minidns.record.Data;
+import de.measite.minidns.record.SRV;
+import de.measite.minidns.util.NameUtil;
+import de.thedevstack.android.logcat.Logging;
+import de.thedevstack.conversationsplus.ConversationsPlusApplication;
+import de.thedevstack.conversationsplus.dto.SrvRecord;
+import de.thedevstack.conversationsplus.Config;
+import de.thedevstack.conversationsplus.xmpp.jid.Jid;
+
+public class DNSHelper {
+    private static final String CLIENT_SRV_PREFIX = "_xmpp-client._tcp.";
+    private static final String SECURE_CLIENT_SRV_PREFIX = "_xmpps-client._tcp.";
+	private static final Pattern PATTERN_IPV4 = Pattern.compile("\\A(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}\\z");
+	private static final Pattern PATTERN_IPV6_HEX4DECCOMPRESSED = Pattern.compile("\\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?) ::((?:[0-9A-Fa-f]{1,4}:)*)(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}\\z");
+	private static final Pattern PATTERN_IPV6_6HEX4DEC = Pattern.compile("\\A((?:[0-9A-Fa-f]{1,4}:){6,6})(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}\\z");
+	private static final Pattern PATTERN_IPV6_HEXCOMPRESSED = Pattern.compile("\\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)\\z");
+	private static final Pattern PATTERN_IPV6 = Pattern.compile("\\A(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}\\z");
+
+	protected static Client client = new Client();
+
+    static {
+        client.setTimeout(Config.PING_TIMEOUT * 1000);
+    }
+
+    /**
+     * Queries the SRV record for the server JID.
+     * This method uses all available Domain Name Servers.
+     * @param jid the server JID
+     * @return TreeSet with SrvRecords. If no SRV record is found for JID an empty TreeSet is returned.
+     */
+    public static final TreeSet<SrvRecord> querySrvRecord(Jid jid) {
+        String host = jid.getDomainpart();
+        TreeSet<SrvRecord> result = new TreeSet<>();
+
+        final List<InetAddress> dnsServers = Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP ? getDnsServers() : getDnsServersPreLollipop();
+
+        if (dnsServers != null) {
+            for (InetAddress dnsServer : dnsServers) {
+                result = querySrvRecord(host, dnsServer);
+                if (!result.isEmpty()) {
+                    break;
+                }
+            }
+        }
+
+        return result;
+    }
+
+	@TargetApi(21)
+	private static List<InetAddress> getDnsServers() {
+		List<InetAddress> servers = new ArrayList<>();
+		ConnectivityManager connectivityManager = (ConnectivityManager) ConversationsPlusApplication.getInstance().getSystemService(Context.CONNECTIVITY_SERVICE);
+		Network[] networks = connectivityManager == null ? null : connectivityManager.getAllNetworks();
+		if (networks == null) {
+			return getDnsServersPreLollipop();
+		}
+		for(int i = 0; i < networks.length; ++i) {
+			LinkProperties linkProperties = connectivityManager.getLinkProperties(networks[i]);
+			if (linkProperties != null) {
+				if (hasDefaultRoute(linkProperties)) {
+					servers.addAll(0, linkProperties.getDnsServers());
+				} else {
+					servers.addAll(linkProperties.getDnsServers());
+				}
+			}
+		}
+		if (servers.size() > 0) {
+            Logging.d("dns", "used lollipop variant to discover dns servers in " + networks.length + " networks");
+		}
+		return servers.size() > 0 ? servers : getDnsServersPreLollipop();
+	}
+
+	@TargetApi(Build.VERSION_CODES.LOLLIPOP)
+	private static boolean hasDefaultRoute(LinkProperties linkProperties) {
+		for(RouteInfo route: linkProperties.getRoutes()) {
+			if (route.isDefaultRoute()) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+	private static List<InetAddress> getDnsServersPreLollipop() {
+		List<InetAddress> servers = new ArrayList<>();
+		String[] dns = client.findDNS();
+		for(int i = 0; i < dns.length; ++i) {
+			try {
+				servers.add(InetAddress.getByName(dns[i]));
+			} catch (UnknownHostException e) {
+				//ignore
+			}
+		}
+		return servers;
+	}
+
+    /**
+     * Queries the SRV record for an host from the given Domain Name Server.
+     * @param host the host to query for
+     * @param dnsServerAddress the DNS to query on
+     * @return TreeSet with SrvRecords.
+     */
+    private static final TreeSet<SrvRecord> querySrvRecord(String host, InetAddress dnsServerAddress) {
+        TreeSet<SrvRecord> result = new TreeSet<>();
+        querySrvRecord(host, dnsServerAddress, false, result);
+        querySrvRecord(host, dnsServerAddress, true, result);
+        return result;
+    }
+
+    private static final void querySrvRecord(String host, InetAddress dnsServerAddress, boolean tlsSrvRecord, TreeSet<SrvRecord> result) {
+        String qname = (tlsSrvRecord ? SECURE_CLIENT_SRV_PREFIX : CLIENT_SRV_PREFIX) + host;
+        String dnsServerHostAddress = dnsServerAddress.getHostAddress();
+        Logging.d("dns", "using dns server: " + dnsServerHostAddress + " to look up " + qname);
+        try {
+            DNSMessage message = client.query(qname, TYPE.SRV, CLASS.IN, dnsServerHostAddress);
+            if (null != message) {
+                Record[] rrset = message.getAnswers();
+                for (Record rr : rrset) {
+                    Data d = rr.getPayload();
+                    if (d instanceof SRV && NameUtil.idnEquals(qname, rr.getName())) {
+                        SRV srv = (SRV) d;
+                        SrvRecord srvRecord = new SrvRecord(srv.getPriority(), srv.getName(), srv.getPort(), tlsSrvRecord);
+                        result.add(srvRecord);
+                    }
+                }
+            } else {
+                Logging.e("dns", "No valid DNS message retrieved.");
+            }
+
+        } catch (IOException e) {
+            Logging.d("dns", "Error while retrieving SRV record '" + qname + "' for '" + host + "' from DNS '" + dnsServerHostAddress + "': " + e.getMessage());
+        }
+    }
+
+	public static boolean isIp(final String server) {
+		return server != null && (
+				PATTERN_IPV4.matcher(server).matches()
+				|| PATTERN_IPV6.matcher(server).matches()
+				|| PATTERN_IPV6_6HEX4DEC.matcher(server).matches()
+				|| PATTERN_IPV6_HEX4DECCOMPRESSED.matcher(server).matches()
+				|| PATTERN_IPV6_HEXCOMPRESSED.matcher(server).matches());
+	}
+}