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Client: Add SRV-based virtual hosting support
When connecting to host names without port (e.g. example.org), the client will now perform an SRV lookup to _jamulus._udp.example.org. If this lookup returns exactly one result, the result is used to select the actual target address/port. If the lookup does not return a usable result, the regular connect logic kicks in (A lookup, default port). Related: https://github.com/orgs/jamulussoftware/discussions/1772
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3 files changed

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‎src/client.cpp‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -477,7 +477,11 @@ void CClient::StartDelayTimer()
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bool CClient::SetServerAddr ( QString strNAddr )
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{
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CHostAddress HostAddress;
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#ifdef CLIENT_NO_SRV_CONNECT
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if ( NetworkUtil().ParseNetworkAddress ( strNAddr, HostAddress, bEnableIPv6 ) )
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#else
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if ( NetworkUtil().ParseNetworkAddressWithSrvDiscovery ( strNAddr, HostAddress, bEnableIPv6 ) )
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#endif
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{
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// apply address to the channel
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Channel.SetAddress ( HostAddress );

‎src/util.cpp‎

Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -914,6 +914,75 @@ bool NetworkUtil::ParseNetworkAddressString ( QString strAddress, QHostAddress&
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return false;
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}
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#ifndef CLIENT_NO_SRV_CONNECT
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bool NetworkUtil::ParseNetworkAddressSrv ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 )
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{
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// init requested host address with invalid address first
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HostAddress = CHostAddress();
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QRegularExpression plainHostRegex ( "^([^\\[:0-9.][^:]*)$" );
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if ( plainHostRegex.match ( strAddress ).capturedStart() != 0 )
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{
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// not a plain hostname? then don't attempt SRV lookup and fail
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// immediately.
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return false;
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}
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QDnsLookup* dns = new QDnsLookup();
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dns->setType ( QDnsLookup::SRV );
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dns->setName ( QString ( "_jamulus._udp.%1" ).arg ( strAddress ) );
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dns->lookup();
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// QDnsLookup::lookup() works asynchronously. Therefore, wait for
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// it to complete here by resuming the main loop here.
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// This is not nice and blocks the UI, but is similar to what
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// the regular resolve function does as well.
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QTime dieTime = QTime::currentTime().addMSecs ( DNS_SRV_RESOLVE_TIMEOUT_MS );
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while ( QTime::currentTime() < dieTime && !dns->isFinished() )
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{
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QCoreApplication::processEvents ( QEventLoop::ExcludeUserInputEvents, 100 );
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}
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QList<QDnsServiceRecord> records = dns->serviceRecords();
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dns->deleteLater();
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if ( records.length() != 1 )
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{
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return false;
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}
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QDnsServiceRecord record = records.first();
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if ( record.target() == "." || record.target() == "" )
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{
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// RFC2782 says that "." indicates that the service is not available.
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// Qt strips the trailing dot, which is why we check for empty string
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// as well. Therefore, the "." part might be redundant, but this would
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// need further testing to confirm.
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// End processing here (= return true), but pass back an
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// invalid HostAddress to let the connect logic fail properly.
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HostAddress = CHostAddress ( QHostAddress ( "." ), 0 );
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return true;
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}
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qDebug() << qUtf8Printable (
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QString ( "resolved %1 to a single SRV record: %2:%3" ).arg ( strAddress ).arg ( record.target() ).arg ( record.port() ) );
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QHostAddress InetAddr;
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if ( ParseNetworkAddressString ( record.target(), InetAddr, bEnableIPv6 ) )
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{
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HostAddress = CHostAddress ( InetAddr, record.port() );
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return true;
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}
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return false;
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}
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bool NetworkUtil::ParseNetworkAddressWithSrvDiscovery ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 )
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{
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// Try SRV-based discovery first:
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if ( ParseNetworkAddressSrv ( strAddress, HostAddress, bEnableIPv6 ) )
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{
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return true;
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}
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// Try regular connect via plain IP or host name lookup (A/AAAA):
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return ParseNetworkAddress ( strAddress, HostAddress, bEnableIPv6 );
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}
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#endif
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bool NetworkUtil::ParseNetworkAddress ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 )
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{
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QHostAddress InetAddr;

‎src/util.h‎

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,9 @@
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#include <QElapsedTimer>
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#include <QTextBoundaryFinder>
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#include <QTimer>
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#ifndef CLIENT_NO_SRV_CONNECT
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# include <QDnsLookup>
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#endif
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#ifndef _WIN32
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# include <QThread>
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#endif
@@ -79,8 +82,9 @@ class CClient; // forward declaration of CClient
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#endif
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/* Definitions ****************************************************************/
82-
#define METER_FLY_BACK 2
83-
#define INVALID_MIDI_CH -1 // invalid MIDI channel definition
85+
#define METER_FLY_BACK 2
86+
#define INVALID_MIDI_CH -1 // invalid MIDI channel definition
87+
#define DNS_SRV_RESOLVE_TIMEOUT_MS 500
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8589
/* Global functions ***********************************************************/
8690
// converting float to short
@@ -1039,6 +1043,11 @@ class NetworkUtil
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{
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public:
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static bool ParseNetworkAddressString ( QString strAddress, QHostAddress& InetAddr, bool bEnableIPv6 );
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1047+
#ifndef CLIENT_NO_SRV_CONNECT
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static bool ParseNetworkAddressSrv ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 );
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static bool ParseNetworkAddressWithSrvDiscovery ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 );
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#endif
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static bool ParseNetworkAddress ( QString strAddress, CHostAddress& HostAddress, bool bEnableIPv6 );
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static QString FixAddress ( const QString& strAddress );

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