package eu.siacs.conversations.utils; import android.content.Context; import android.support.annotation.NonNull; import android.util.Log; import java.io.IOException; import java.net.Inet4Address; import java.net.InetAddress; import java.util.ArrayList; import java.util.Collections; import java.util.List; import de.measite.minidns.DNSClient; import de.measite.minidns.DNSName; import de.measite.minidns.dnssec.DNSSECResultNotAuthenticException; import de.measite.minidns.hla.DnssecResolverApi; import de.measite.minidns.hla.ResolverApi; import de.measite.minidns.hla.ResolverResult; 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 registerXmppConnectionService(XmppConnectionService service) { Resolver.SERVICE = service; registerLookupMechanism(service); } private static void registerLookupMechanism(Context context) { DNSClient.addDnsServerLookupMechanism(new AndroidUsingLinkProperties(context)); } public static List resolve(String domain) { List results = new ArrayList<>(); try { results.addAll(resolveSrv(domain,true)); } catch (IOException e) { Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+e.getMessage()); } try { results.addAll(resolveSrv(domain,false)); } catch (IOException e) { Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+e.getMessage()); } if (results.size() == 0) { results.addAll(resolveNoSrvRecords(DNSName.from(domain),true)); } Collections.sort(results); Log.d(Config.LOGTAG,Resolver.class.getSimpleName()+": "+results.toString()); return results; } private static List resolveSrv(String domain, final boolean directTls) throws IOException { if (Thread.currentThread().isInterrupted()) { return Collections.emptyList(); } DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE)+"._tcp."+domain); ResolverResult result = resolveWithFallback(dnsName,SRV.class); List results = new ArrayList<>(); for(SRV record : result.getAnswersOrEmptySet()) { final boolean addedIPv4 = results.addAll(resolveIp(record,A.class,result.isAuthenticData(),directTls)); results.addAll(resolveIp(record,AAAA.class,result.isAuthenticData(),directTls)); if (!addedIPv4 && !Thread.currentThread().isInterrupted()) { Result resolverResult = Result.fromRecord(record, directTls); resolverResult.authenticated = resolverResult.isAuthenticated(); results.add(resolverResult); } } return results; } private static List resolveIp(SRV srv, Class type, boolean authenticated, boolean directTls) { if (Thread.currentThread().isInterrupted()) { return Collections.emptyList(); } List list = new ArrayList<>(); try { ResolverResult results = resolveWithFallback(DNSName.from(srv.name.toString()),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); } if (results.size() == 0) { 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 { if (!validateHostname) { return ResolverApi.INSTANCE.resolve(dnsName, type); } try { final ResolverResult r = DnssecResolverApi.INSTANCE.resolveDnssecReliable(dnsName, type); if (r.wasSuccessful()) { if (r.getAnswers().isEmpty() && type.equals(SRV.class)) { Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": resolving SRV records of " + dnsName.toString() + " with DNSSEC yielded empty result"); } return r; } Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": error resolving " + type.getSimpleName() + " with DNSSEC. Trying DNS instead.", r.getResolutionUnsuccessfulException()); } 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(dnsName, type); } private static boolean validateHostname() { return SERVICE != null && SERVICE.getBooleanPreference("validate_hostname", R.bool.validate_hostname); } public static class Result implements Comparable { private InetAddress ip; private DNSName hostname; private int port = 5222; private boolean directTls = false; private boolean authenticated =false; private int priority; 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 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; } public static Result createDefault(DNSName hostname, InetAddress ip) { Result result = new Result(); result.port = 5222; result.hostname = hostname; result.ip = ip; return result; } public static Result createDefault(DNSName hostname) { return createDefault(hostname,null); } } }