Networkstack: easy happy eyeball

src/main/java/eu/siacs/conversations/persistance/DatabaseBackend.java

@@ -63,7 +63,7 @@ import rocks.xmpp.addr.Jid;
 public class DatabaseBackend extends SQLiteOpenHelper {
 
     private static final String DATABASE_NAME = "history";
-    private static final int DATABASE_VERSION = 46;
+    private static final int DATABASE_VERSION = 47;
     private static DatabaseBackend instance = null;
     private static String CREATE_CONTATCS_STATEMENT = "create table "
             + Contact.TABLENAME + "(" + Contact.ACCOUNT + " TEXT, "
@@ -160,6 +160,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
             + Resolver.Result.DIRECT_TLS + " NUMBER,"
             + Resolver.Result.AUTHENTICATED + " NUMBER,"
             + Resolver.Result.PORT + " NUMBER,"
+            + Resolver.Result.TIME_REQUESTED + " NUMBER,"
             + "UNIQUE(" + Resolver.Result.DOMAIN + ") ON CONFLICT REPLACE"
             + ");";
 
@@ -513,10 +514,6 @@ public class DatabaseBackend extends SQLiteOpenHelper {
             db.execSQL("ALTER TABLE " + Message.TABLENAME + " ADD COLUMN " + Message.MARKABLE + " NUMBER DEFAULT 0");
         }
 
-        if (oldVersion < 39 && newVersion >= 39) {
-            db.execSQL(CREATE_RESOLVER_RESULTS_TABLE);
-        }
-
         if (oldVersion < 41 && newVersion >= 41) {
             db.execSQL(CREATE_MESSAGE_INDEX_TABLE);
             db.execSQL(CREATE_MESSAGE_INSERT_TRIGGER);
@@ -555,6 +552,13 @@ public class DatabaseBackend extends SQLiteOpenHelper {
             final long diff = SystemClock.elapsedRealtime() - start;
             Log.d(Config.LOGTAG,"deleted old edit information in "+diff+"ms");
         }
+
+	if (oldVersion < 47 && newVersion >= 47) {
+          // values in resolver_result are cache and not worth to store 
+          db.execSQL("DROP TABLE IF EXISTS " + RESOLVER_RESULTS_TABLENAME);
+          db.execSQL(CREATE_RESOLVER_RESULTS_TABLE);
+        }
+
     }
 
     private void canonicalizeJids(SQLiteDatabase db) {

src/main/java/eu/siacs/conversations/utils/Resolver.java

@@ -7,11 +7,17 @@ import android.util.Log;
 
 import java.io.IOException;
 import java.lang.reflect.Field;
-import java.net.Inet4Address;
 import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Socket;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
 import java.util.List;
 
 import de.measite.minidns.AbstractDNSClient;
@@ -33,6 +39,7 @@ 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.persistance.FileBackend;
 import eu.siacs.conversations.services.XmppConnectionService;
 
 public class Resolver {
@@ -40,7 +47,7 @@ public class Resolver {
     public static final int DEFAULT_PORT_XMPP = 5222;
 
     private static final String DIRECT_TLS_SERVICE = "_xmpps-client";
-    private static final String STARTTLS_SERICE = "_xmpp-client";
+    private static final String STARTTLS_SERVICE = "_xmpp-client";
 
     private static XmppConnectionService SERVICE = null;
 
@@ -74,13 +81,13 @@ public class Resolver {
         }
     }
 
-    public static List<Result> fromHardCoded(String hostname, int port) {
-        Result result = new Result();
-        result.hostname = DNSName.from(hostname);
-        result.port = port;
-        result.directTls = useDirectTls(port);
-        result.authenticated = true;
-        return Collections.singletonList(result);
+    public static Result fromHardCoded(String hostname, int port) {
+        final Result ipResult = fromIpAddress(hostname, port);
+        if (ipResult != null) {
+            ipResult.connect();
+            return ipResult;
+        }
+        return happyEyeball(resolveNoSrvRecords(DNSName.from(hostname), port, true));
     }
 
 
@@ -88,10 +95,11 @@ public class Resolver {
         return port == 443 || port == 5223;
     }
 
-    public static List<Result> resolve(String domain) {
-        final  List<Result> ipResults = fromIpAddress(domain);
-        if (ipResults.size() > 0) {
-            return ipResults;
+    public static Result resolve(String domain) {
+        final Result ipResult = fromIpAddress(domain, DEFAULT_PORT_XMPP);
+        if (ipResult != null) {
+            ipResult.connect();
+            return ipResult;
         }
         final List<Result> results = new ArrayList<>();
         final List<Result> fallbackResults = new ArrayList<>();
@@ -117,7 +125,7 @@ public class Resolver {
             }
         });
         threads[2] = new Thread(() -> {
-            List<Result> list = resolveNoSrvRecords(DNSName.from(domain), true);
+            List<Result> list = resolveNoSrvRecords(DNSName.from(domain), DEFAULT_PORT_XMPP, true);
             synchronized (fallbackResults) {
                 fallbackResults.addAll(list);
             }
@@ -132,66 +140,80 @@ public class Resolver {
                 threads[2].interrupt();
                 synchronized (results) {
                     Collections.sort(results);
-                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + results.toString());
-                    return new ArrayList<>(results);
+                    return happyEyeball(results);
                 }
             } else {
                 threads[2].join();
                 synchronized (fallbackResults) {
                     Collections.sort(fallbackResults);
-                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": " + fallbackResults.toString());
-                    return new ArrayList<>(fallbackResults);
+                    return happyEyeball(fallbackResults);
                 }
             }
         } catch (InterruptedException e) {
             for (Thread thread : threads) {
                 thread.interrupt();
             }
-            return Collections.emptyList();
+            return null;
         }
     }
 
-    private static List<Result> fromIpAddress(String domain) {
+    private static Result fromIpAddress(String domain, int port) {
         if (!IP.matches(domain)) {
-            return Collections.emptyList();
+            return null;
         }
         try {
             Result result = new Result();
             result.ip = InetAddress.getByName(domain);
-            result.port = DEFAULT_PORT_XMPP;
-            return Collections.singletonList(result);
+            result.port = port;
+            result.authenticated = true;
+            return result;
         } catch (UnknownHostException e) {
-            return Collections.emptyList();
+            return null;
         }
     }
 
     private static List<Result> resolveSrv(String domain, final boolean directTls) throws IOException {
-        DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERICE) + "._tcp." + domain);
+        DNSName dnsName = DNSName.from((directTls ? DIRECT_TLS_SERVICE : STARTTLS_SERVICE) + "._tcp." + domain);
         ResolverResult<SRV> result = resolveWithFallback(dnsName, SRV.class);
         final List<Result> results = new ArrayList<>();
         final List<Thread> threads = new ArrayList<>();
+
+        final List<Result> fallbackResults = new ArrayList<>();
+        final List<Thread> fallbackThreads = new ArrayList<>();
         for (SRV record : result.getAnswersOrEmptySet()) {
-            if (record.name.length() == 0 && record.priority == 0) {
+            if (record.name.length() == 0) {
                 continue;
             }
-            threads.add(new Thread(() -> {
-                final List<Result> ipv4s = resolveIp(record, A.class, result.isAuthenticData(), directTls);
-                if (ipv4s.size() == 0) {
-                    Result resolverResult = Result.fromRecord(record, directTls);
-                    resolverResult.authenticated = result.isAuthenticData();
-                    ipv4s.add(resolverResult);
-                }
-                synchronized (results) {
-                    results.addAll(ipv4s);
-                }
-
-            }));
             threads.add(new Thread(() -> {
                 final List<Result> ipv6s = resolveIp(record, AAAA.class, result.isAuthenticData(), directTls);
                 synchronized (results) {
                     results.addAll(ipv6s);
                 }
             }));
+            threads.add(new Thread(() -> {
+                final List<Result> ipv4s = resolveIp(record, A.class, result.isAuthenticData(), directTls);
+                synchronized (results) {
+                    results.addAll(ipv4s);
+                }
+            }));
+            fallbackThreads.add(new Thread(() -> {
+                try {
+                    ResolverResult<CNAME> cnames = resolveWithFallback(record.name, CNAME.class, result.isAuthenticData());
+                    for (CNAME cname : cnames.getAnswersOrEmptySet()) {
+                        final List<Result> ipv6s = resolveIp(record, cname.name, AAAA.class, cnames.isAuthenticData(), directTls);
+                        synchronized (fallbackResults) {
+                            fallbackResults.addAll(ipv6s);
+                        }
+                        final List<Result> ipv4s = resolveIp(record, cname.name, A.class, cnames.isAuthenticData(), directTls);
+                        synchronized (results) {
+                            fallbackResults.addAll(ipv4s);
+                        }
+                    }
+                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + "cname in srv (agains RFC2782) - run slow fallback");
+                } catch (Throwable throwable) {
+                    Log.i(Config.LOGTAG, Resolver.class.getSimpleName() + "error resolving srv cname-fallback records", throwable);
+                }
+            }));
         }
         for (Thread thread : threads) {
             thread.start();
@@ -203,13 +225,30 @@ public class Resolver {
                 return Collections.emptyList();
             }
         }
-        return results;
+        if (results.size() > 0) {
+            return results;
+        }
+
+        for (Thread thread : fallbackThreads) {
+            thread.start();
+        }
+        for (Thread thread : fallbackThreads) {
+            try {
+                thread.join();
+            } catch (InterruptedException e) {
+                return Collections.emptyList();
+            }
+        }
+        return fallbackResults;
     }
 
     private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, Class<D> type, boolean authenticated, boolean directTls) {
+        return resolveIp(srv, srv.name, type, authenticated, directTls);
+    }
+    private static <D extends InternetAddressRR> List<Result> resolveIp(SRV srv, DNSName hostname, Class<D> type, boolean authenticated, boolean directTls) {
         List<Result> list = new ArrayList<>();
         try {
-            ResolverResult<D> results = resolveWithFallback(srv.name, type, authenticated);
+            ResolverResult<D> results = resolveWithFallback(hostname, type, authenticated);
             for (D record : results.getAnswersOrEmptySet()) {
                 Result resolverResult = Result.fromRecord(srv, directTls);
                 resolverResult.authenticated = results.isAuthenticData() && authenticated; //TODO technically it doesn’t matter if the IP was authenticated
@@ -222,24 +261,23 @@ public class Resolver {
         return list;
     }
 
-    private static List<Result> resolveNoSrvRecords(DNSName dnsName, boolean withCnames) {
+    private static List<Result> resolveNoSrvRecords(DNSName dnsName, int port, boolean withCnames) {
         List<Result> 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()));
+                results.add(Result.createDefault(dnsName, aaaa.getInetAddress(), port));
+            }
+            for (A a : resolveWithFallback(dnsName, A.class, false).getAnswersOrEmptySet()) {
+                results.add(Result.createDefault(dnsName, a.getInetAddress(), port));
             }
             if (results.size() == 0 && withCnames) {
                 for (CNAME cname : resolveWithFallback(dnsName, CNAME.class, false).getAnswersOrEmptySet()) {
-                    results.addAll(resolveNoSrvRecords(cname.name, false));
+                    results.addAll(resolveNoSrvRecords(cname.name, port, false));
                 }
             }
         } catch (Throwable throwable) {
             Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + "error resolving fallback records", throwable);
         }
-        results.add(Result.createDefault(dnsName));
         return results;
     }
 
@@ -264,11 +302,57 @@ public class Resolver {
         return ResolverApi.INSTANCE.resolve(question);
     }
 
+    private static Result happyEyeball(List<Result> r) {
+        String logID = Long.toHexString(Double.doubleToLongBits(Math.random()));
+        Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": happy eyeball (" + logID + ") with " + r.toString());
+        if (r.size() == 0) return null;
+
+        Result result;
+        if (r.size() == 1) {
+            result = r.get(0);
+            result.setLogID(logID);
+            result.connect();
+            return result;
+        }
+
+        for (Result res : r) {
+            res.setLogID(logID);
+        }
+
+        ExecutorService executor = Executors.newFixedThreadPool(4);
+
+        try {
+            result = executor.invokeAny(r);
+            executor.shutdown();
+            Thread disconnector = new Thread(() -> {
+                while (true) {
+                    try {
+                        if (executor.awaitTermination(5, TimeUnit.SECONDS)) break;
+                        Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": happy eyeball (" + logID + ") wait for cleanup ...");
+                    } catch (InterruptedException e) {}
+                }
+                Log.i(Config.LOGTAG, Resolver.class.getSimpleName() + ": happy eyeball (" + logID + ") cleanup");
+                for (Result re : r) {
+                    if(!re.equals(result)) re.disconnect();
+                }
+            });
+            disconnector.start();
+            Log.i(Config.LOGTAG, Resolver.class.getSimpleName() + ": happy eyeball (" + logID + ") used: " + result.toString());
+            return result;
+        } catch (InterruptedException e) {
+            Log.e(Config.LOGTAG, Resolver.class.getSimpleName() + ": happy eyeball (" + logID + ") failed: ", e);
+            return null;
+        } catch (ExecutionException e) {
+            Log.i(Config.LOGTAG, Resolver.class.getSimpleName() + ": happy eyeball (" + logID + ") unable to connect to one address");
+            return null;
+        }
+    }
+
     private static boolean validateHostname() {
         return SERVICE != null && SERVICE.getBooleanPreference("validate_hostname", R.bool.validate_hostname);
     }
 
-    public static class Result implements Comparable<Result> {
+    public static class Result implements Comparable<Result>, Callable<Result> {
         public static final String DOMAIN = "domain";
         public static final String IP = "ip";
         public static final String HOSTNAME = "hostname";
@@ -276,15 +360,22 @@ public class Resolver {
         public static final String PRIORITY = "priority";
         public static final String DIRECT_TLS = "directTls";
         public static final String AUTHENTICATED = "authenticated";
+        public static final String TIME_REQUESTED = "time_requested";
+
         private InetAddress ip;
         private DNSName hostname;
         private int port = DEFAULT_PORT_XMPP;
         private boolean directTls = false;
         private boolean authenticated = false;
         private int priority;
+        private long timeRequested;
+        private Socket socket;
+
+        private String logID = "";
 
         static Result fromRecord(SRV srv, boolean directTls) {
             Result result = new Result();
+            result.timeRequested = System.currentTimeMillis();
             result.port = srv.port;
             result.hostname = srv.name;
             result.directTls = directTls;
@@ -292,34 +383,15 @@ public class Resolver {
             return result;
         }
  
-        static Result createDefault(DNSName hostname, InetAddress ip) {
+        static Result createDefault(DNSName hostname, InetAddress ip, int port) {
             Result result = new Result();
-            result.port = DEFAULT_PORT_XMPP;
+            result.timeRequested = System.currentTimeMillis();
+            result.port = port;
             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;
-            }
-            final String hostname = cursor.getString(cursor.getColumnIndex(HOSTNAME));
-            result.hostname = hostname == null ? null : DNSName.from(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;
@@ -346,14 +418,6 @@ public class Resolver {
             return result;
         }
 
-        public InetAddress getIp() {
-            return ip;
-        }
-
-        public int getPort() {
-            return port;
-        }
-
         public DNSName getHostname() {
             return hostname;
         }
@@ -366,11 +430,19 @@ public class Resolver {
             return authenticated;
         }
 
+        public boolean isOutdated() {
+            return (System.currentTimeMillis() - timeRequested) > 300_000;
+        }
+
+        public Socket getSocket() {
+            return socket;
+        }
+
         @Override
         public String toString() {
             return "Result{" +
                     "ip='" + (ip == null ? null : ip.getHostAddress()) + '\'' +
-                    ", hostame='" + (hostname == null ? null : hostname.toString()) + '\'' +
+                    ", hostname='" + (hostname == null ? null : hostname.toString()) + '\'' +
                     ", port=" + port +
                     ", directTls=" + directTls +
                     ", authenticated=" + authenticated +
@@ -378,21 +450,47 @@ public class Resolver {
                     '}';
         }
 
+        public void connect() {
+            if (this.socket != null) {
+                this.disconnect();
+            }
+            final InetSocketAddress addr = new InetSocketAddress(this.ip, this.port);
+            this.socket = new Socket();
+            try {
+                long time = System.currentTimeMillis();
+                this.socket.connect(addr, Config.SOCKET_TIMEOUT * 1000);
+                time = System.currentTimeMillis() - time;
+                if (!this.logID.isEmpty()) {
+                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": Result (" + this.logID + ") connect: " + toString() + " after: " + time + " ms");
+                } else {
+                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": Result connect: " + toString() + " after: " + time + " ms");
+                }
+            } catch (IOException e) {
+                this.disconnect();
+            }
+        }
+
+        public void disconnect() {
+            if (this.socket != null ) {
+                FileBackend.close(this.socket);
+                this.socket = null;
+                if (!this.logID.isEmpty()) {
+                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": Result (" + this.logID + ") disconnect: " + toString());
+                } else {
+                    Log.d(Config.LOGTAG, Resolver.class.getSimpleName() + ": Result disconnect: " + toString());
+                }
+            }
+        }
+
+        public void setLogID(String logID) {
+            this.logID = logID;
+        }
+
         @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;
-                    }
+                    return 0;
                 } else {
                     return directTls ? -1 : 1;
                 }
@@ -400,6 +498,32 @@ public class Resolver {
                 return priority - result.priority;
             }
         }
+        @Override
+        public Result call() throws Exception {
+            this.connect();
+            if (this.socket != null && this.socket.isConnected()) {
+                return this;
+            }
+            throw new Exception("Resolver.Result was not possible to connect - should be catched by executor");
+        }
+
+        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;
+            }
+            final String hostname = cursor.getString(cursor.getColumnIndex(HOSTNAME));
+            result.hostname = hostname == null ? null : DNSName.from(hostname);
+            result.port = cursor.getInt(cursor.getColumnIndex(PORT));
+            result.directTls = cursor.getInt(cursor.getColumnIndex(DIRECT_TLS)) > 0;
+            result.authenticated = cursor.getInt(cursor.getColumnIndex(AUTHENTICATED)) > 0;
+            result.priority = cursor.getInt(cursor.getColumnIndex(PRIORITY));
+            result.timeRequested = cursor.getLong(cursor.getColumnIndex(TIME_REQUESTED));
+            return result;
+        }
+
 
         public ContentValues toContentValues() {
             final ContentValues contentValues = new ContentValues();
@@ -409,6 +533,7 @@ public class Resolver {
             contentValues.put(PRIORITY, priority);
             contentValues.put(DIRECT_TLS, directTls ? 1 : 0);
             contentValues.put(AUTHENTICATED, authenticated ? 1 : 0);
+            contentValues.put(TIME_REQUESTED, timeRequested);
             return contentValues;
         }
     }

src/main/java/eu/siacs/conversations/xmpp/XmppConnection.java

@@ -291,86 +291,59 @@ public class XmppConnection implements Runnable {
                 }
             } else {
                 final String domain = account.getJid().getDomain();
-                final List<Resolver.Result> results;
+                final Resolver.Result storedBackupResult = mXmppConnectionService.databaseBackend.findResolverResult(domain);
+                Resolver.Result result = null;
                 final boolean hardcoded = extended && !account.getHostname().isEmpty();
                 if (hardcoded) {
-                    results = Resolver.fromHardCoded(account.getHostname(), account.getPort());
-                } else {
-                    results = Resolver.resolve(domain);
+                    result = Resolver.fromHardCoded(account.getHostname(), account.getPort());
+                } else if (storedBackupResult != null && !storedBackupResult.isOutdated()) {
+                    storedBackupResult.connect();
+                    result = storedBackupResult;
+                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": loaded backup resolver result from db: " + storedBackupResult);
+                }
+                if (result == null || result.getSocket() == null) {
+                    result = Resolver.resolve(domain);
+                }
+                if (result == null) {
+                    throw new UnknownHostException();
                 }
                 if (Thread.currentThread().isInterrupted()) {
                     Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": Thread was interrupted");
                     return;
                 }
-                if (results.size() == 0) {
-                    Log.e(Config.LOGTAG,account.getJid().asBareJid()+": Resolver results were empty");
+                try {
+                    // if tls is true, encryption is implied and must not be started
+                    features.encryptionEnabled = result.isDirectTls();
+                    verifiedHostname = result.isAuthenticated() ? result.getHostname().toString() : null;
+                    Log.d(Config.LOGTAG,"verified hostname " + verifiedHostname);
+                    Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
+                            + ": using values from resolver " + result.toString());
+
+                    localSocket = result.getSocket();
+
+                    if (features.encryptionEnabled) {
+                        localSocket = upgradeSocketToTls(localSocket);
+                    }
+
+                    localSocket.setSoTimeout(Config.SOCKET_TIMEOUT * 1000);
+                    if (startXmpp(localSocket)) {
+                        localSocket.setSoTimeout(0); //reset to 0; once the connection is established we don’t want this
+                        if (!hardcoded && !result.equals(storedBackupResult)) {
+                            mXmppConnectionService.databaseBackend.saveResolverResult(domain, result);
+                        }
+                        // successfully connected to server that speaks xmpp
+                    } else {
+                        FileBackend.close(localSocket);
+                        throw new StateChangingException(Account.State.STREAM_OPENING_ERROR);
+                    }
+                } catch (final StateChangingException e) {
+                    throw e;
+                } catch (InterruptedException e) {
+                    Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": thread was interrupted before beginning stream");
                     return;
-                }
-                final Resolver.Result storedBackupResult;
-                if (hardcoded) {
-                    storedBackupResult = null;
-                } else {
-                    storedBackupResult = mXmppConnectionService.databaseBackend.findResolverResult(domain);
-                    if (storedBackupResult != null && !results.contains(storedBackupResult)) {
-                        results.add(storedBackupResult);
-                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": loaded backup resolver result from db: " + storedBackupResult);
-                    }
-                }
-                for (Iterator<Resolver.Result> iterator = results.iterator(); iterator.hasNext(); ) {
-                    final Resolver.Result result = iterator.next();
-                    if (Thread.currentThread().isInterrupted()) {
-                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": Thread was interrupted");
-                        return;
-                    }
-                    try {
-                        // if tls is true, encryption is implied and must not be started
-                        features.encryptionEnabled = result.isDirectTls();
-                        verifiedHostname = result.isAuthenticated() ? result.getHostname().toString() : null;
-                        Log.d(Config.LOGTAG,"verified hostname "+verifiedHostname);
-                        final InetSocketAddress addr;
-                        if (result.getIp() != null) {
-                            addr = new InetSocketAddress(result.getIp(), result.getPort());
-                            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
-                                    + ": using values from resolver " + (result.getHostname() == null ? "" : result.getHostname().toString()
-                                    + "/") + result.getIp().getHostAddress() + ":" + result.getPort() + " tls: " + features.encryptionEnabled);
-                        } else {
-                            addr = new InetSocketAddress(IDN.toASCII(result.getHostname().toString()), result.getPort());
-                            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString()
-                                    + ": using values from resolver "
-                                    + result.getHostname().toString() + ":" + result.getPort() + " tls: " + features.encryptionEnabled);
-                        }
-
-                        localSocket = new Socket();
-                        localSocket.connect(addr, Config.SOCKET_TIMEOUT * 1000);
-
-                        if (features.encryptionEnabled) {
-                            localSocket = upgradeSocketToTls(localSocket);
-                        }
-
-                        localSocket.setSoTimeout(Config.SOCKET_TIMEOUT * 1000);
-                        if (startXmpp(localSocket)) {
-                            localSocket.setSoTimeout(0); //reset to 0; once the connection is established we don’t want this
-                            if (!hardcoded && !result.equals(storedBackupResult)) {
-                                mXmppConnectionService.databaseBackend.saveResolverResult(domain, result);
-                            }
-                            break; // successfully connected to server that speaks xmpp
-                        } else {
-                            FileBackend.close(localSocket);
-                            throw new StateChangingException(Account.State.STREAM_OPENING_ERROR);
-                        }
-                    } catch (final StateChangingException e) {
-                        if (!iterator.hasNext()) {
-                            throw e;
-                        }
-                    } catch (InterruptedException e) {
-                        Log.d(Config.LOGTAG, account.getJid().asBareJid() + ": thread was interrupted before beginning stream");
-                        return;
-                    } catch (final Throwable e) {
-                        Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": " + e.getMessage() + "(" + e.getClass().getName() + ")");
-                        if (!iterator.hasNext()) {
-                            throw new UnknownHostException();
-                        }
-                    }
+                } catch (final Throwable e) {
+                    Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": " + e.getMessage() + "(" + e.getClass().getName() + ")");
+                    throw new UnknownHostException();
                 }
             }
             processStream();
@@ -384,8 +357,12 @@ public class XmppConnection implements Runnable {
             this.changeStatus(Account.State.SERVER_NOT_FOUND);
         } catch (final SocksSocketFactory.SocksProxyNotFoundException e) {
             this.changeStatus(Account.State.TOR_NOT_AVAILABLE);
-        } catch (final IOException | XmlPullParserException  e) {
-            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": " + e.getMessage());
+        } catch (final IOException e) {
+            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": socket io :" + e.getMessage());
+            this.changeStatus(Account.State.OFFLINE);
+            this.attempt = Math.max(0, this.attempt - 1);
+        } catch (final XmlPullParserException  e) {
+            Log.d(Config.LOGTAG, account.getJid().asBareJid().toString() + ": xml parser :" + e.getMessage());
             this.changeStatus(Account.State.OFFLINE);
             this.attempt = Math.max(0, this.attempt - 1);
         } finally {