Implement UDP multicast on Windows

The code is very similar to the UNIX version, but not identical. It
appears the Microsoft compiler does not like the "interface" variable
name, so they have been renamed.

The autotest had a bug in it that I failed to notice before. The sender
was not sending to the multicast group, it was sending to the local
address of the receiver (which fails on Windows).

1 files changed, 104 insertions, 0 deletions

diff --git a/src/network/socket/qnativesocketengine_win.cpp b/src/network/socket/qnativesocketengine_win.cpp
index 477ef45..d222fd1 100644
--- a/src/network/socket/qnativesocketengine_win.cpp
+++ b/src/network/socket/qnativesocketengine_win.cpp
@@ -40,6 +40,7 @@
 ****************************************************************************/
 
 #include <winsock2.h>
+#include <ws2tcpip.h>
 
 #include "qnativesocketengine_p.h"
 
@@ -47,6 +48,7 @@
 #include <qsocketnotifier.h>
 #include <qdebug.h>
 #include <qdatetime.h>
+#include <qnetworkinterface.h>
 
 //#define QNATIVESOCKETENGINE_DEBUG
 #if defined(QNATIVESOCKETENGINE_DEBUG)
@@ -399,6 +401,13 @@ int QNativeSocketEnginePrivate::option(QNativeSocketEngine::SocketOption opt) co
     case QNativeSocketEngine::KeepAliveOption:
         n = SO_KEEPALIVE;
         break;
+    case QNativeSocketEngine::MulticastLoopback:
+        {
+            unsigned long val = 0;
+            if (WSAIoctl(socketDescriptor, SIO_MULTIPOINT_LOOPBACK, 0, 0, &val, sizeof(val), 0, 0, 0) == 0)
+                return val;
+            return -1;
+        }
     }
 
     int v = -1;
@@ -459,6 +468,14 @@ bool QNativeSocketEnginePrivate::setOption(QNativeSocketEngine::SocketOption opt
     case QNativeSocketEngine::KeepAliveOption:
         n = SO_KEEPALIVE;
         break;
+    case QNativeSocketEngine::MulticastLoopback:
+        {
+            unsigned long val = v, outval;
+            if (WSAIoctl(socketDescriptor, SIO_MULTIPOINT_LOOPBACK, &val, sizeof(val), &outval, sizeof(outval), 0, 0, 0) == 0)
+                return true;
+            WS_ERROR_DEBUG(WSAGetLastError());
+            return false;
+        }
     }
 
     if (::setsockopt(socketDescriptor, level, n, (char*)&v, sizeof(v)) != 0) {
@@ -747,6 +764,93 @@ int QNativeSocketEnginePrivate::nativeAccept()
     return acceptedDescriptor;
 }
 
+static bool doMulticast(QNativeSocketEnginePrivate *d,
+                        int how6,
+                        int how4,
+                        const QHostAddress &groupAddress,
+                        const QNetworkInterface &iface)
+{
+    int sockOpt = 0;
+    char *sockArg;
+    int sockArgSize;
+
+    struct ip_mreq mreq4;
+#ifndef QT_NO_IPV6
+    struct ipv6_mreq mreq6;
+
+    if (groupAddress.protocol() == QAbstractSocket::IPv6Protocol) {
+       sockOpt = how6;
+        sockArg = reinterpret_cast<char *>(&mreq6);
+        sockArgSize = sizeof(mreq6);
+        memset(&mreq6, 0, sizeof(mreq6));
+        Q_IPV6ADDR ip6 = groupAddress.toIPv6Address();
+        memcpy(&mreq6.ipv6mr_multiaddr, &ip6, sizeof(ip6));
+        mreq6.ipv6mr_interface = iface.index();
+    } else
+#endif
+    if (groupAddress.protocol() == QAbstractSocket::IPv4Protocol) {
+        sockOpt = how4;
+        sockArg = reinterpret_cast<char *>(&mreq4);
+        sockArgSize = sizeof(mreq4);
+        memset(&mreq4, 0, sizeof(mreq4));
+        mreq4.imr_multiaddr.s_addr = htonl(groupAddress.toIPv4Address());
+
+        if (iface.isValid()) {
+            QList<QNetworkAddressEntry> addressEntries = iface.addressEntries();
+            if (!addressEntries.isEmpty()) {
+                QHostAddress firstIP = addressEntries.first().ip();
+                mreq4.imr_interface.s_addr = htonl(firstIP.toIPv4Address());
+            } else {
+                d->setError(QAbstractSocket::NetworkError,
+                            QNativeSocketEnginePrivate::NetworkUnreachableErrorString);
+                return false;
+            }
+        } else {
+            mreq4.imr_interface.s_addr = INADDR_ANY;
+        }
+    } else {
+        // unreachable
+        d->setError(QAbstractSocket::UnsupportedSocketOperationError,
+                    QNativeSocketEnginePrivate::ProtocolUnsupportedErrorString);
+        return false;
+    }
+
+    int res = setsockopt(d->socketDescriptor, IPPROTO_IP, sockOpt, sockArg, sockArgSize);
+    if (res == -1) {
+        d->setError(QAbstractSocket::UnsupportedSocketOperationError,
+                    QNativeSocketEnginePrivate::OperationUnsupportedErrorString);
+        return false;
+    }
+    return true;
+}
+
+bool QNativeSocketEnginePrivate::nativeJoinMulticastGroup(const QHostAddress &groupAddress,
+                                                          const QNetworkInterface &iface)
+{
+    return doMulticast(this,
+#ifndef QT_NO_IPV6
+                       IPV6_JOIN_GROUP,
+#else
+                       0,
+#endif
+                       IP_ADD_MEMBERSHIP,
+                       groupAddress,
+                       iface);
+}
+
+bool QNativeSocketEnginePrivate::nativeLeaveMulticastGroup(const QHostAddress &groupAddress,
+                                                           const QNetworkInterface &iface)
+{
+    return doMulticast(this,
+#ifndef QT_NO_IPV6
+                       IPV6_LEAVE_GROUP,
+#else
+                       0,
+#endif
+                       IP_DROP_MEMBERSHIP,
+                       groupAddress,
+                       iface);
+}
 
 qint64 QNativeSocketEnginePrivate::nativeBytesAvailable() const
 {