IPv4 + IPv6 dual stack sockets

Adds support for binding "dual stack" sockets (via QUdpSocket or
QTcpServer). A dual stack socket will accept incoming connections on
either IPv4 or IPv6 interfaces.

QHostAddress::Any     - use this to bind a dual stack socket
QHostAddress::AnyIPv6 - use this to bind a socket for IPv6 only
QHostAddress::AnyIPv4 - use this to bind a socket for IPv4 only

Binding to a specific address rather than one of the "any" addresses
is restricting you to a protocol anyway so no behaviour change there.
IPv6 sockets were previously dual stack on some OS and v6 only on others
Any previously meant IPv4 only

This commit implemented & tested on Windows 7, Linux (Ubuntu 10.04)
and Mac OS 10.6.7.

Windows XP and server 2003 do not support dual stack sockets, even though
they can support IPv6. On those versions, QHostAddress::Any will still
bind to IPv4 0.0.0.0 (which is also the behaviour anywhere QT_NO_IPV6 is
defined)

Autotests run:
qudpsocket (includes a new test case)
qtcpserver (includes a new test case)
qtcpsocket
qnetworkreply
qhostaddress

Task-number: QTBUG-17080
Change-Id: Id486677c4f832e18dc0ff1a86c5f5fc422c9eb4f
Reviewed-on: http://codereview.qt.nokia.com/421
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Thiago Macieira <thiago.macieira@nokia.com>
Reviewed-by: Markus Goetz

2 files changed, 55 insertions, 10 deletions

diff --git a/src/network/kernel/qhostaddress.cpp b/src/network/kernel/qhostaddress.cpp
index 7eeb4e5a51..bff351c34f 100644
--- a/src/network/kernel/qhostaddress.cpp
+++ b/src/network/kernel/qhostaddress.cpp
@@ -134,15 +134,40 @@ QHostAddressPrivate::QHostAddressPrivate()
 void QHostAddressPrivate::setAddress(quint32 a_)
 {
     a = a_;
+    //create mapped address
+    memset(&a6, 0, sizeof(a6));
+    int i;
+    for (i=15; a_ != 0; i--) {
+        a6[i] = a_ & 0xFF;
+        a_ >>=8;
+    }
+    Q_ASSERT(i >= 11);
+    a6[11] = 0xFF;
+    a6[10] = 0xFF;
     protocol = QAbstractSocket::IPv4Protocol;
     isParsed = true;
 }
 
+static bool parseMappedAddress(quint32& a, const Q_IPV6ADDR &a6)
+{
+    int i;
+    for (i=0;i<10;i++)
+        if (a6[i]) return false;
+    for (;i<12;i++)
+        if (a6[i] != 0xFF) return false;
+    a=(a6[12] << 24) | (a6[13] << 16) | (a6[14] << 8) | a6[15];
+    return true;
+}
+
 void QHostAddressPrivate::setAddress(const quint8 *a_)
 {
     for (int i = 0; i < 16; i++)
         a6[i] = a_[i];
-    protocol = QAbstractSocket::IPv6Protocol;
+    a = 0;
+    if (parseMappedAddress(a, a6))
+        protocol = QAbstractSocket::IPv4Protocol;
+    else
+        protocol = QAbstractSocket::IPv6Protocol;
     isParsed = true;
 }
 
@@ -150,7 +175,10 @@ void QHostAddressPrivate::setAddress(const Q_IPV6ADDR &a_)
 {
     a6 = a_;
     a = 0;
-    protocol = QAbstractSocket::IPv6Protocol;
+    if (parseMappedAddress(a, a6))
+        protocol = QAbstractSocket::IPv4Protocol;
+    else
+        protocol = QAbstractSocket::IPv6Protocol;
     isParsed = true;
 }
 
@@ -447,8 +475,9 @@ void QNetmaskAddress::setPrefixLength(QAbstractSocket::NetworkLayerProtocol prot
     \value LocalHost The IPv4 localhost address. Equivalent to QHostAddress("127.0.0.1").
     \value LocalHostIPv6 The IPv6 localhost address. Equivalent to QHostAddress("::1").
     \value Broadcast The IPv4 broadcast address. Equivalent to QHostAddress("255.255.255.255").
-    \value Any The IPv4 any-address. Equivalent to QHostAddress("0.0.0.0").
-    \value AnyIPv6 The IPv6 any-address. Equivalent to QHostAddress("::").
+    \value AnyIPv4 The IPv4 any-address. Equivalent to QHostAddress("0.0.0.0"). A socket bound with this address will listen only on IPv4 interaces.
+    \value AnyIPv6 The IPv6 any-address. Equivalent to QHostAddress("::"). A socket bound with this address will listen only on IPv6 interaces.
+    \value Any The dual stack any-address. A socket bound with this address will listen on both IPv4 and IPv6 interfaces.
 */
 
 /*!  Constructs a host address object with the IP address 0.0.0.0.
@@ -548,12 +577,16 @@ QHostAddress::QHostAddress(SpecialAddress address)
     case LocalHostIPv6:
         setAddress(QLatin1String("::1"));
         break;
-    case Any:
+    case AnyIPv4:
         setAddress(QLatin1String("0.0.0.0"));
         break;
     case AnyIPv6:
         setAddress(QLatin1String("::"));
         break;
+    case Any:
+        d->clear();
+        d->protocol = QAbstractSocket::AnyIPProtocol;
+        break;
     }
 }
 
@@ -679,8 +712,11 @@ void QHostAddress::setAddress(const struct sockaddr *sockaddr)
     For example, if the address is 127.0.0.1, the returned value is
     2130706433 (i.e. 0x7f000001).
 
-    This value is only valid if the Protocol() is
-    \l{QAbstractSocket::}{IPv4Protocol}.
+    This value is valid if the protocol() is
+    \l{QAbstractSocket::}{IPv4Protocol},
+    or if the protocol is
+    \l{QAbstractSocket::}{IPv6Protocol},
+    and the IPv6 address is an IPv4 mapped address. (RFC4291)
 
     \sa toString()
 */
@@ -705,8 +741,11 @@ QAbstractSocket::NetworkLayerProtocol QHostAddress::protocol() const
 
     \snippet doc/src/snippets/code/src_network_kernel_qhostaddress.cpp 0
 
-    This value is only valid if the protocol() is
+    This value is valid if the protocol() is
     \l{QAbstractSocket::}{IPv6Protocol}.
+    If the protocol is
+    \l{QAbstractSocket::}{IPv4Protocol},
+    then the address is returned an an IPv4 mapped IPv6 address. (RFC4291)
 
     \sa toString()
 */
@@ -722,13 +761,15 @@ Q_IPV6ADDR QHostAddress::toIPv6Address() const
     For example, if the address is the IPv4 address 127.0.0.1, the
     returned string is "127.0.0.1". For IPv6 the string format will 
     follow the RFC5952 recommendation.
+    For QHostAddress::Any, its IPv4 address will be returned ("0.0.0.0")
 
     \sa toIPv4Address()
 */
 QString QHostAddress::toString() const
 {
     QT_ENSURE_PARSED(this);
-    if (d->protocol == QAbstractSocket::IPv4Protocol) {
+    if (d->protocol == QAbstractSocket::IPv4Protocol
+        || d->protocol == QAbstractSocket::AnyIPProtocol) {
         quint32 i = toIPv4Address();
         QString s;
         s.sprintf("%d.%d.%d.%d", (i>>24) & 0xff, (i>>16) & 0xff,
@@ -1183,6 +1224,9 @@ QDataStream &operator>>(QDataStream &in, QHostAddress &address)
         address.setScopeId(scope);
     }
         break;
+    case QAbstractSocket::AnyIPProtocol:
+        address = QHostAddress::Any;
+        break;
     default:
         address.clear();
         in.setStatus(QDataStream::ReadCorruptData);
diff --git a/src/network/kernel/qhostaddress.h b/src/network/kernel/qhostaddress.h
index 486f2322ae..efb3198fc0 100644
--- a/src/network/kernel/qhostaddress.h
+++ b/src/network/kernel/qhostaddress.h
@@ -76,7 +76,8 @@ public:
         LocalHost,
         LocalHostIPv6,
         Any,
-        AnyIPv6
+        AnyIPv6,
+        AnyIPv4
     };
 
     QHostAddress();