X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fmidi%2B%2B2%2Fipmidi_port.cc;h=fd5cb9a2395e727a457dda57104038439ea0429b;hb=466141229f0402c807902f9fc42446bd4416c600;hp=848276b220e9e420b677a7f6fb32cc59dceb7f5d;hpb=b520db4687f35692c071f6b2c37473280fb81f90;p=ardour.git

diff --git a/libs/midi++2/ipmidi_port.cc b/libs/midi++2/ipmidi_port.cc
index 848276b220..fd5cb9a239 100644
--- a/libs/midi++2/ipmidi_port.cc
+++ b/libs/midi++2/ipmidi_port.cc
@@ -231,36 +231,43 @@ IPMIDIPort::open_sockets (int base_port, const string& ifname)
 	addrout.sin_addr.s_addr = ::inet_addr("225.0.0.37");
 	addrout.sin_port = htons (base_port);
 
-#ifndef PLATFORM_WINDOWS
-	int loop;
-	socklen_t size;
+	// Turn off loopback...
+	int loop = 0;
+
+#ifdef PLATFORM_WINDOWS
+
+	/* https://msdn.microsoft.com/en-us/library/windows/desktop/ms739161%28v=vs.85%29.aspx
+	 *
+	 * ------------------------------------------------------------------------------
+	 * Note The Winsock version of the IP_MULTICAST_LOOP option is
+	 * semantically different than the UNIX version of the
+	 * IP_MULTICAST_LOOP option:
+	 *
+	 * In Winsock, the IP_MULTICAST_LOOP option applies only to the receive path.
+	 * In the UNIX version, the IP_MULTICAST_LOOP option applies to the send path.
+	 *
+	 * For example, applications ON and OFF (which are easier to track than
+	 * X and Y) join the same group on the same interface; application ON
+	 * sets the IP_MULTICAST_LOOP option on, application OFF sets the
+	 * IP_MULTICAST_LOOP option off. If ON and OFF are Winsock
+	 * applications, OFF can send to ON, but ON cannot sent to OFF. In
+	 * contrast, if ON and OFF are UNIX applications, ON can send to OFF,
+	 * but OFF cannot send to ON.
+	 * ------------------------------------------------------------------------------
+	 *
+	 * Alles klar? Gut! 
+	 */
+
+	const int target_sock = sockin;
 #else
-	u_char loop;
-	int size;
+	const int target_sock = sockout;
 #endif
 
-	if (::getsockopt (sockin, IPPROTO_IP, IP_MULTICAST_LOOP, (char *) &loop, &size)) {
-		// ::perror ("getsockopt(IP_MULTICAST_LOOP)");
-		cout << "Cannot get loopback status\n";
-	} else {
-		cout << "********* 1. multicast loopback: " << loop << " size was " << size << endl;
-	}
-
-	// Turn off loopback...
-	loop = 0;
-	if (::setsockopt(sockout, IPPROTO_IP, IP_MULTICAST_LOOP, (char *) &loop, sizeof (loop)) < 0) {
-		//::perror("setsockopt(IP_MULTICAST_LOOP)");
-		cout << "Cannot set loopback status\n";
+	if (::setsockopt (target_sock, IPPROTO_IP, IP_MULTICAST_LOOP, (char *) &loop, sizeof (loop)) < 0) {
+		::perror("setsockopt(IP_MULTICAST_LOOP)");
 		return false;
 	}
 
-	if (::getsockopt (sockin, IPPROTO_IP, IP_MULTICAST_LOOP, (char *) &loop, &size)) {
-		// ::perror ("getsockopt(IP_MULTICAST_LOOP)");
-		cout << "Cannot Get loopback status 2\n";
-	} else {
-		cout << "********* 2. multicast loopback: " << loop << " size was " << size << endl;
-	}
-
 #ifndef PLATFORM_WINDOWS
 
 	if (fcntl (sockin, F_SETFL, O_NONBLOCK)) {
@@ -286,7 +293,7 @@ IPMIDIPort::open_sockets (int base_port, const string& ifname)
 		return false;
 	}
 #endif
-	cout << "ipmidi ports setup!!!!!!!\n";
+
 	return true;
 }