Merge pull request #2930 from hoffie/client-srv-support

Client: Add SRV-based virtual hosting support
jamulussoftware · Nov 15, 2022 · 26701d9 · 26701d9
2 parents d070ff8 + ed18ad6
commit 26701d9
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Showing 3 changed files with 111 additions and 27 deletions.
diff --git a/src/client.cpp b/src/client.cpp
@@ -477,7 +477,11 @@ void CClient::StartDelayTimer()
 bool CClient::SetServerAddr ( QString strNAddr )
 {
     CHostAddress HostAddress;
+#ifdef CLIENT_NO_SRV_CONNECT
     if ( NetworkUtil().ParseNetworkAddress ( strNAddr, HostAddress, bEnableIPv6 ) )
+#else
+    if ( NetworkUtil().ParseNetworkAddressWithSrvDiscovery ( strNAddr, HostAddress, bEnableIPv6 ) )
+#endif
     {
         // apply address to the channel
         Channel.SetAddress ( HostAddress );

diff --git a/src/util.cpp b/src/util.cpp
@@ -890,6 +890,100 @@ QSize CMinimumStackedLayout::sizeHint() const
 * Other Classes                                                                *
 \******************************************************************************/
 // Network utility functions ---------------------------------------------------
+bool NetworkUtil::ParseNetworkAddressString ( QString strAddress, QHostAddress& InetAddr, bool bEnableIPv6 )
+{
+    // try to get host by name, assuming
+    // that the string contains a valid host name string or IP address
+    const QHostInfo HostInfo = QHostInfo::fromName ( strAddress );
+
+    if ( HostInfo.error() != QHostInfo::NoError )
+    {
+        // qInfo() << qUtf8Printable ( QString ( "Invalid hostname" ) );
+        return false; // invalid address
+    }
+
+    foreach ( const QHostAddress HostAddr, HostInfo.addresses() )
+    {
+        // qInfo() << qUtf8Printable ( QString ( "Resolved network address to %1 for proto %2" ) .arg ( HostAddr.toString() ) .arg (
+        // HostAddr.protocol() ) );
+        if ( HostAddr.protocol() == QAbstractSocket::IPv4Protocol || ( bEnableIPv6 && HostAddr.protocol() == QAbstractSocket::IPv6Protocol ) )
+        {
+            InetAddr = HostAddr;
+            return true;
+        }
+    }
+    return false;
+}
+
+#ifndef CLIENT_NO_SRV_CONNECT
+bool NetworkUtil::ParseNetworkAddressSrv ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 )
+{
+    // init requested host address with invalid address first
+    HostAddress = CHostAddress();
+
+    QRegularExpression plainHostRegex ( "^([^\\[:0-9.][^:]*)$" );
+    if ( plainHostRegex.match ( strAddress ).capturedStart() != 0 )
+    {
+        // not a plain hostname? then don't attempt SRV lookup and fail
+        // immediately.
+        return false;
+    }
+
+    QDnsLookup* dns = new QDnsLookup();
+    dns->setType ( QDnsLookup::SRV );
+    dns->setName ( QString ( "_jamulus._udp.%1" ).arg ( strAddress ) );
+    dns->lookup();
+    // QDnsLookup::lookup() works asynchronously. Therefore, wait for
+    // it to complete here by resuming the main loop here.
+    // This is not nice and blocks the UI, but is similar to what
+    // the regular resolve function does as well.
+    QTime dieTime = QTime::currentTime().addMSecs ( DNS_SRV_RESOLVE_TIMEOUT_MS );
+    while ( QTime::currentTime() < dieTime && !dns->isFinished() )
+    {
+        QCoreApplication::processEvents ( QEventLoop::ExcludeUserInputEvents, 100 );
+    }
+    QList<QDnsServiceRecord> records = dns->serviceRecords();
+    dns->deleteLater();
+    if ( records.length() != 1 )
+    {
+        return false;
+    }
+    QDnsServiceRecord record = records.first();
+    if ( record.target() == "." || record.target() == "" )
+    {
+        // RFC2782 says that "." indicates that the service is not available.
+        // Qt strips the trailing dot, which is why we check for empty string
+        // as well. Therefore, the "." part might be redundant, but this would
+        // need further testing to confirm.
+        // End processing here (= return true), but pass back an
+        // invalid HostAddress to let the connect logic fail properly.
+        HostAddress = CHostAddress ( QHostAddress ( "." ), 0 );
+        return true;
+    }
+    qDebug() << qUtf8Printable (
+        QString ( "resolved %1 to a single SRV record: %2:%3" ).arg ( strAddress ).arg ( record.target() ).arg ( record.port() ) );
+
+    QHostAddress InetAddr;
+    if ( ParseNetworkAddressString ( record.target(), InetAddr, bEnableIPv6 ) )
+    {
+        HostAddress = CHostAddress ( InetAddr, record.port() );
+        return true;
+    }
+    return false;
+}
+
+bool NetworkUtil::ParseNetworkAddressWithSrvDiscovery ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 )
+{
+    // Try SRV-based discovery first:
+    if ( ParseNetworkAddressSrv ( strAddress, HostAddress, bEnableIPv6 ) )
+    {
+        return true;
+    }
+    // Try regular connect via plain IP or host name lookup (A/AAAA):
+    return ParseNetworkAddress ( strAddress, HostAddress, bEnableIPv6 );
+}
+#endif
+
 bool NetworkUtil::ParseNetworkAddress ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 )
 {
     QHostAddress InetAddr;
@@ -971,31 +1065,7 @@ bool NetworkUtil::ParseNetworkAddress ( QString strAddress, CHostAddress& HostAd
             return false; // invalid address
         }
 
-        // try to get host by name, assuming
-        // that the string contains a valid host name string
-        const QHostInfo HostInfo = QHostInfo::fromName ( strAddress );
-
-        if ( HostInfo.error() != QHostInfo::NoError )
-        {
-            // qInfo() << qUtf8Printable ( QString ( "Invalid hostname" ) );
-            return false; // invalid address
-        }
-
-        bool bFoundAddr = false;
-
-        foreach ( const QHostAddress HostAddr, HostInfo.addresses() )
-        {
-            // qInfo() << qUtf8Printable ( QString ( "Resolved network address to %1 for proto %2" ) .arg ( HostAddr.toString() ) .arg (
-            // HostAddr.protocol() ) );
-            if ( HostAddr.protocol() == QAbstractSocket::IPv4Protocol || ( bEnableIPv6 && HostAddr.protocol() == QAbstractSocket::IPv6Protocol ) )
-            {
-                InetAddr   = HostAddr;
-                bFoundAddr = true;
-                break;
-            }
-        }
-
-        if ( !bFoundAddr )
+        if ( !ParseNetworkAddressString ( strAddress, InetAddr, bEnableIPv6 ) )
         {
             // no valid address found
             // qInfo() << qUtf8Printable ( QString ( "No IP address found for hostname" ) );

diff --git a/src/util.h b/src/util.h
@@ -53,6 +53,9 @@
 #include <QElapsedTimer>
 #include <QTextBoundaryFinder>
 #include <QTimer>
+#ifndef CLIENT_NO_SRV_CONNECT
+#    include <QDnsLookup>
+#endif
 #ifndef _WIN32
 #    include <QThread>
 #endif
@@ -79,8 +82,9 @@ class CClient; // forward declaration of CClient
 #endif
 
 /* Definitions ****************************************************************/
-#define METER_FLY_BACK  2
-#define INVALID_MIDI_CH -1 // invalid MIDI channel definition
+#define METER_FLY_BACK             2
+#define INVALID_MIDI_CH            -1 // invalid MIDI channel definition
+#define DNS_SRV_RESOLVE_TIMEOUT_MS 500
 
 /* Global functions ***********************************************************/
 // converting float to short
@@ -1039,6 +1043,12 @@ class CNetworkTransportProps
 class NetworkUtil
 {
 public:
+    static bool ParseNetworkAddressString ( QString strAddress, QHostAddress& InetAddr, bool bEnableIPv6 );
+
+#ifndef CLIENT_NO_SRV_CONNECT
+    static bool ParseNetworkAddressSrv ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 );
+    static bool ParseNetworkAddressWithSrvDiscovery ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 );
+#endif
     static bool ParseNetworkAddress ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 );
 
     static QString      FixAddress ( const QString& strAddress );