auto-connect to next DNS-SRV record server on connection failure

automatically try next server from DNS SRV record when connection
to first can not be established

1 files changed, 23 insertions, 5 deletions

diff --git a/src/client/QXmppOutgoingClient.cpp b/src/client/QXmppOutgoingClient.cpp
index b5c7052a..9d5043d0 100644
--- a/src/client/QXmppOutgoingClient.cpp
+++ b/src/client/QXmppOutgoingClient.cpp
@@ -60,6 +60,7 @@ class QXmppOutgoingClientPrivate
 public:
     QXmppOutgoingClientPrivate(QXmppOutgoingClient *q);
     void connectToHost(const QString &host, quint16 port);
+    void connectToNextDNSHost();
 
     void sendNonSASLAuth(bool plaintext);
     void sendNonSASLAuthQuery();
@@ -74,6 +75,7 @@ public:
 
     // DNS
     QDnsLookup dns;
+    int nextSrvRecordIdx;
 
     // Stream
     QString streamId;
@@ -113,7 +115,8 @@ private:
 };
 
 QXmppOutgoingClientPrivate::QXmppOutgoingClientPrivate(QXmppOutgoingClient *qq)
-    : redirectPort(0)
+    : nextSrvRecordIdx(0)
+    , redirectPort(0)
     , bindModeAvailable(false)
     , sessionAvailable(false)
     , sessionStarted(false)
@@ -156,6 +159,15 @@ void QXmppOutgoingClientPrivate::connectToHost(const QString &host, quint16 port
     }
 }
 
+void QXmppOutgoingClientPrivate::connectToNextDNSHost()
+{
+    connectToHost(
+        dns.serviceRecords().at(nextSrvRecordIdx).target(),
+        dns.serviceRecords().at(nextSrvRecordIdx).port());
+
+    nextSrvRecordIdx++;
+}
+
 /// Constructs an outgoing client stream.
 ///
 /// \param parent
@@ -245,6 +257,7 @@ void QXmppOutgoingClient::connectToHost()
     d->dns.setName("_xmpp-client._tcp." + domain);
     d->dns.setType(QDnsLookup::SRV);
     d->dns.lookup();
+    d->nextSrvRecordIdx = 0;
 }
 
 void QXmppOutgoingClient::disconnectFromHost()
@@ -258,9 +271,7 @@ void QXmppOutgoingClient::_q_dnsLookupFinished()
     if (d->dns.error() == QDnsLookup::NoError &&
         !d->dns.serviceRecords().isEmpty()) {
         // take the first returned record
-        d->connectToHost(
-            d->dns.serviceRecords().first().target(),
-            d->dns.serviceRecords().first().port());
+        d->connectToNextDNSHost();
     } else {
         // as a fallback, use domain as the host name
         warning(QString("Lookup for domain %1 failed: %2")
@@ -314,7 +325,14 @@ void QXmppOutgoingClient::socketSslErrors(const QList<QSslError> &errors)
 void QXmppOutgoingClient::socketError(QAbstractSocket::SocketError socketError)
 {
     Q_UNUSED(socketError);
-    emit error(QXmppClient::SocketError);
+    if ( !d->sessionStarted &&
+         (d->dns.serviceRecords().count() > d->nextSrvRecordIdx) )
+    {
+        // some network error occured during startup -> try next available SRV record server
+        d->connectToNextDNSHost();
+    }
+    else
+        emit error(QXmppClient::SocketError);
 }
 
 /// \cond