package eu.siacs.conversations.utils; import android.content.ContentValues; import android.database.Cursor; import android.support.annotation.NonNull; import android.util.Log; import java.io.IOException; import java.lang.reflect.Field; import java.net.Inet4Address; import java.net.InetAddress; import java.net.UnknownHostException; import java.util.ArrayList; import java.util.Collections; import java.util.List; import de.measite.minidns.AbstractDNSClient; import de.measite.minidns.DNSClient; 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; import de.measite.minidns.iterative.ReliableDNSClient; import de.measite.minidns.record.A; import de.measite.minidns.record.AAAA; import de.measite.minidns.record.CNAME; import de.measite.minidns.record.Data; import de.measite.minidns.record.InternetAddressRR; import de.measite.minidns.record.SRV; import eu.siacs.conversations.Config; import eu.siacs.conversations.R; import eu.siacs.conversations.services.XmppConnectionService; public class Resolver { private static final String DIRECT_TLS_SERVICE = "_xmpps-client"; private static final String STARTTLS_SERICE = "_xmpp-client"; private static XmppConnectionService SERVICE = null; 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); } } private static void disableHardcodedDnsServers(ReliableDNSClient reliableDNSClient) { try { final Field dnsClientField = ReliableDNSClient.class.getDeclaredField("dnsClient"); dnsClientField.setAccessible(true); final DNSClient dnsClient = (DNSClient) dnsClientField.get(reliableDNSClient); dnsClient.getDataSource().setTimeout(3000); final Field useHardcodedDnsServers = DNSClient.class.getDeclaredField("useHardcodedDnsServers"); useHardcodedDnsServers.setAccessible(true); useHardcodedDnsServers.setBoolean(dnsClient, false); } catch (NoSuchFieldException | IllegalAccessException e) { Log.e(Config.LOGTAG, "Unable to disable hardcoded DNS servers", e); } } public static List resolve(String domain) { final List results = new ArrayList<>(); final List fallbackResults = new ArrayList<>(); Thread[] threads = new Thread[3]; threads[0] = new Thread(() -> { try { final List list = resolveSrv(domain, true); synchronized (results) { results.addAll(list); } } catch (Throwable throwable) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving SRV record (direct TLS)", throwable); } }); threads[1] = new Thread(() -> { try { final List list = resolveSrv(domain, false); synchronized (results) { results.addAll(list); } } catch (Throwable throwable) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving SRV record (STARTTLS)", throwable); } }); threads[2] = new Thread(() -> { List list = resolveNoSrvRecords(DNSName.from(domain), true); synchronized (fallbackResults) { fallbackResults.addAll(list); } }); for (Thread thread : threads) { thread.start(); } try { threads[0].join(); threads[1].join(); if (results.size() > 0) { threads[2].interrupt(); synchronized (results) { Collections.sort(results); Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + results.toString()); return new ArrayList<>(results); } } else { threads[2].join(); synchronized (fallbackResults) { Collections.sort(fallbackResults); Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + fallbackResults.toString()); return new ArrayList<>(fallbackResults); } } } catch (InterruptedException e) { for(Thread thread : threads) { thread.interrupt(); } synchronized (results) { return new ArrayList<>(results); } } } private static List resolveSrv(String domain, final boolean directTls) throws IOException { DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE) + "._tcp." + domain); ResolverResult result = resolveWithFallback(dnsName, SRV.class); final List results = new ArrayList<>(); final List threads = new ArrayList<>(); for (SRV record : result.getAnswersOrEmptySet()) { if (record.name.length() == 0 && record.priority == 0) { continue; } threads.add(new Thread(() -> { final List ipv4s = resolveIp(record, A.class, result.isAuthenticData(), directTls); if (ipv4s.size() == 0) { Result resolverResult = Result.fromRecord(record, directTls); resolverResult.authenticated = resolverResult.isAuthenticated(); ipv4s.add(resolverResult); } synchronized (results) { results.addAll(ipv4s); } })); threads.add(new Thread(() -> { final List ipv6s = resolveIp(record, AAAA.class, result.isAuthenticData(), directTls); synchronized (results) { results.addAll(ipv6s); } })); } for (Thread thread : threads) { thread.start(); } for (Thread thread : threads) { try { thread.join(); } catch (InterruptedException e) { return Collections.emptyList(); } } return results; } private static List resolveIp(SRV srv, Class type, boolean authenticated, boolean directTls) { List list = new ArrayList<>(); try { ResolverResult results = resolveWithFallback(srv.name, type, authenticated); for (D record : results.getAnswersOrEmptySet()) { Result resolverResult = Result.fromRecord(srv, directTls); resolverResult.authenticated = results.isAuthenticData() && authenticated; resolverResult.ip = record.getInetAddress(); list.add(resolverResult); } } catch (Throwable t) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " " + t.getMessage()); } return list; } private static List resolveNoSrvRecords(DNSName dnsName, boolean withCnames) { List results = new ArrayList<>(); try { for (A a : resolveWithFallback(dnsName, A.class, false).getAnswersOrEmptySet()) { results.add(Result.createDefault(dnsName, a.getInetAddress())); } for (AAAA aaaa : resolveWithFallback(dnsName, AAAA.class, false).getAnswersOrEmptySet()) { results.add(Result.createDefault(dnsName, aaaa.getInetAddress())); } if (results.size() == 0 && withCnames) { for (CNAME cname : resolveWithFallback(dnsName, CNAME.class, false).getAnswersOrEmptySet()) { results.addAll(resolveNoSrvRecords(cname.name, false)); } } } catch (Throwable throwable) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + "error resolving fallback records", throwable); } results.add(Result.createDefault(dnsName)); return results; } private static ResolverResult resolveWithFallback(DNSName dnsName, Class type) throws IOException { return resolveWithFallback(dnsName, type, validateHostname()); } private static ResolverResult resolveWithFallback(DNSName dnsName, Class type, boolean validateHostname) throws IOException { final Question question = new Question(dnsName, Record.TYPE.getType(type)); if (!validateHostname) { return ResolverApi.INSTANCE.resolve(question); } try { return DnssecResolverApi.INSTANCE.resolveDnssecReliable(question); } catch (DNSSECResultNotAuthenticException e) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", e); } catch (IOException e) { throw e; } catch (Throwable throwable) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", throwable); } return ResolverApi.INSTANCE.resolve(question); } private static boolean validateHostname() { return SERVICE != null && SERVICE.getBooleanPreference("validate_hostname", R.bool.validate_hostname); } public static class Result implements Comparable { public static final String DOMAIN = "domain"; public static final String IP = "ip"; public static final String HOSTNAME = "hostname"; public static final String PORT = "port"; public static final String PRIORITY = "priority"; public static final String DIRECT_TLS = "directTls"; public static final String AUTHENTICATED = "authenticated"; private InetAddress ip; private DNSName hostname; private int port = 5222; private boolean directTls = false; private boolean authenticated = false; private int priority; static Result fromRecord(SRV srv, boolean directTls) { Result result = new Result(); result.port = srv.port; result.hostname = srv.name; result.directTls = directTls; result.priority = srv.priority; return result; } static Result createDefault(DNSName hostname, InetAddress ip) { Result result = new Result(); result.port = 5222; result.hostname = hostname; result.ip = ip; return result; } static Result createDefault(DNSName hostname) { return createDefault(hostname, null); } public static Result fromCursor(Cursor cursor) { final Result result = new Result(); try { result.ip = InetAddress.getByAddress(cursor.getBlob(cursor.getColumnIndex(IP))); } catch (UnknownHostException e) { result.ip = null; } result.hostname = DNSName.from(cursor.getString(cursor.getColumnIndex(HOSTNAME))); result.port = cursor.getInt(cursor.getColumnIndex(PORT)); result.priority = cursor.getInt(cursor.getColumnIndex(PRIORITY)); result.authenticated = cursor.getInt(cursor.getColumnIndex(AUTHENTICATED)) > 0; result.directTls = cursor.getInt(cursor.getColumnIndex(DIRECT_TLS)) > 0; return result; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Result result = (Result) o; if (port != result.port) return false; if (directTls != result.directTls) return false; if (authenticated != result.authenticated) return false; if (priority != result.priority) return false; if (ip != null ? !ip.equals(result.ip) : result.ip != null) return false; return hostname != null ? hostname.equals(result.hostname) : result.hostname == null; } @Override public int hashCode() { int result = ip != null ? ip.hashCode() : 0; result = 31 * result + (hostname != null ? hostname.hashCode() : 0); result = 31 * result + port; result = 31 * result + (directTls ? 1 : 0); result = 31 * result + (authenticated ? 1 : 0); result = 31 * result + priority; return result; } public InetAddress getIp() { return ip; } public int getPort() { return port; } public DNSName getHostname() { return hostname; } public boolean isDirectTls() { return directTls; } public boolean isAuthenticated() { return authenticated; } @Override public String toString() { return "Result{" + "ip='" + (ip == null ? null : ip.getHostAddress()) + '\'' + ", hostame='" + hostname.toString() + '\'' + ", port=" + port + ", directTls=" + directTls + ", authenticated=" + authenticated + ", priority=" + priority + '}'; } @Override public int compareTo(@NonNull Result result) { if (result.priority == priority) { if (directTls == result.directTls) { if (ip == null && result.ip == null) { return 0; } else if (ip != null && result.ip != null) { if (ip instanceof Inet4Address && result.ip instanceof Inet4Address) { return 0; } else { return ip instanceof Inet4Address ? -1 : 1; } } else { return ip != null ? -1 : 1; } } else { return directTls ? -1 : 1; } } else { return priority - result.priority; } } public ContentValues toContentValues() { final ContentValues contentValues = new ContentValues(); contentValues.put(IP, ip == null ? null : ip.getAddress()); contentValues.put(HOSTNAME, hostname.toString()); contentValues.put(PORT, port); contentValues.put(PRIORITY, priority); contentValues.put(DIRECT_TLS, directTls ? 1 : 0); contentValues.put(AUTHENTICATED, authenticated ? 1 : 0); return contentValues; } } }