QNetworkInterface: add a Linux backend directly using AF_NETLINK

This allows us a lot greater detail in getting information than relying
on getifaddrs() function. It is also the only way of getting some extra
information we'll need in the future, like address lifetimes.

The parser will also be helpful if we want to add a network interface
monitor in the future, though I currently have no clue how to do the
equivalent on macOS and Windows.

This commit does not remove the support for getifaddrs() on Linux, but I
will no longer add features to it. Note that Android does not support
getifaddrs(), so this may be an improvement if AF_NETLINK works there.

Change-Id: I3868166e5efc45538544fffd14d8e6f993e1eb91
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

4 files changed, 467 insertions, 38 deletions

diff --git a/src/network/kernel/kernel.pri b/src/network/kernel/kernel.pri
index 54b61f3ad3..806cdc85cf 100644
--- a/src/network/kernel/kernel.pri
+++ b/src/network/kernel/kernel.pri
@@ -17,6 +17,7 @@ HEADERS += kernel/qtnetworkglobal.h \
            kernel/qnetworkdatagram_p.h \
            kernel/qnetworkinterface.h \
            kernel/qnetworkinterface_p.h \
+           kernel/qnetworkinterface_unix_p.h \
            kernel/qnetworkproxy.h
 
 SOURCES += kernel/qauthenticator.cpp \
@@ -34,7 +35,10 @@ qtConfig(ftp) {
 
 unix {
     !integrity: SOURCES += kernel/qdnslookup_unix.cpp
-    SOURCES += kernel/qhostinfo_unix.cpp kernel/qnetworkinterface_unix.cpp
+    SOURCES += kernel/qhostinfo_unix.cpp
+
+    qtConfig(linux-netlink): SOURCES += kernel/qnetworkinterface_linux.cpp
+    else: SOURCES += kernel/qnetworkinterface_unix.cpp
 }
 
 android {
diff --git a/src/network/kernel/qnetworkinterface_linux.cpp b/src/network/kernel/qnetworkinterface_linux.cpp
new file mode 100644
index 0000000000..8d77d288cd
--- /dev/null
+++ b/src/network/kernel/qnetworkinterface_linux.cpp
@@ -0,0 +1,359 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtNetwork module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qnetworkinterface.h"
+#include "qnetworkinterface_p.h"
+#include "qnetworkinterface_unix_p.h"
+
+#include <qendian.h>
+#include <qobjectdefs.h>
+#include <qvarlengtharray.h>
+
+// accordding to rtnetlink(7)
+#include <asm/types.h>
+#include <linux/if.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <sys/socket.h>
+
+QT_BEGIN_NAMESPACE
+
+enum {
+    BufferSize = 8192
+};
+
+namespace {
+struct NetlinkSocket
+{
+    int sock;
+    NetlinkSocket(int bufferSize)
+    {
+        sock = qt_safe_socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+        if (Q_UNLIKELY(sock == -1))
+            qErrnoWarning("Could not create AF_NETLINK socket");
+
+        // set buffer length
+        socklen_t len = sizeof(bufferSize);
+        setsockopt(sock, SOL_SOCKET, SO_SNDBUF, &bufferSize, len);
+    }
+
+    ~NetlinkSocket()
+    {
+        if (sock != -1)
+            qt_safe_close(sock);
+    }
+
+    operator int() const { return sock; }
+};
+
+template <typename Lambda> struct ProcessNetlinkRequest
+{
+    using FunctionTraits = QtPrivate::FunctionPointer<decltype(&Lambda::operator())>;
+    using FirstArgument = typename FunctionTraits::Arguments::Car;
+
+    static int expectedTypeForRequest(int rtype)
+    {
+        Q_STATIC_ASSERT(RTM_NEWADDR == RTM_GETADDR - 2);
+        Q_STATIC_ASSERT(RTM_NEWLINK == RTM_GETLINK - 2);
+        Q_ASSERT(rtype == RTM_GETADDR || rtype == RTM_GETLINK);
+        return rtype - 2;
+    }
+
+    void operator()(int sock, nlmsghdr *hdr, char *buf, size_t bufsize, Lambda &&func)
+    {
+        // send the request
+        if (send(sock, hdr, hdr->nlmsg_len, 0) != hdr->nlmsg_len)
+            return;
+
+        // receive and parse the request
+        int expectedType = expectedTypeForRequest(hdr->nlmsg_type);
+        const bool isDump = hdr->nlmsg_flags & NLM_F_DUMP;
+        forever {
+            qssize_t len = recv(sock, buf, bufsize, 0);
+            hdr = reinterpret_cast<struct nlmsghdr *>(buf);
+            if (!NLMSG_OK(hdr, len))
+                return;
+
+            auto arg = reinterpret_cast<FirstArgument>(NLMSG_DATA(hdr));
+            size_t payloadLen = NLMSG_PAYLOAD(hdr, 0);
+
+            // is this a multipart message?
+            Q_ASSERT(isDump == !!(hdr->nlmsg_flags & NLM_F_MULTI));
+            if (!isDump) {
+                // no, single message
+                if (hdr->nlmsg_type == expectedType && payloadLen >= sizeof(FirstArgument))
+                    return void(func(arg, payloadLen));
+            } else {
+                // multipart, parse until done
+                do {
+                    if (hdr->nlmsg_type == NLMSG_DONE)
+                        return;
+                    if (hdr->nlmsg_type != expectedType || payloadLen < sizeof(FirstArgument))
+                        break;
+                    func(arg, payloadLen);
+
+                    // NLMSG_NEXT also updates the len variable
+                    hdr = NLMSG_NEXT(hdr, len);
+                    arg = reinterpret_cast<FirstArgument>(NLMSG_DATA(hdr));
+                    payloadLen = NLMSG_PAYLOAD(hdr, 0);
+                } while (NLMSG_OK(hdr, len));
+
+                if (len == 0)
+                    continue;       // get new datagram
+            }
+
+#ifndef QT_NO_DEBUG
+            if (NLMSG_OK(hdr, len))
+                qWarning("QNetworkInterface/AF_NETLINK: received unknown packet type (%d) or too short (%u)",
+                         hdr->nlmsg_type, hdr->nlmsg_len);
+            else
+                qWarning("QNetworkInterface/AF_NETLINK: received invalid packet with size %d", int(len));
+#endif
+            return;
+        }
+    }
+};
+
+template <typename Lambda>
+void processNetlinkRequest(int sock, struct nlmsghdr *hdr, char *buf, size_t bufsize, Lambda &&l)
+{
+    ProcessNetlinkRequest<Lambda>()(sock, hdr, buf, bufsize, std::forward<Lambda>(l));
+}
+}
+
+uint QNetworkInterfaceManager::interfaceIndexFromName(const QString &name)
+{
+    uint index = 0;
+    if (name.length() >= IFNAMSIZ)
+        return index;
+
+    int socket = qt_safe_socket(AF_INET, SOCK_DGRAM, 0);
+    if (socket >= 0) {
+        struct ifreq req;
+        req.ifr_ifindex = 0;
+        strcpy(req.ifr_name, name.toLatin1().constData());
+
+        if (qt_safe_ioctl(socket, SIOCGIFINDEX, &req) >= 0)
+            index = req.ifr_ifindex;
+        qt_safe_close(socket);
+    }
+    return index;
+}
+
+QString QNetworkInterfaceManager::interfaceNameFromIndex(uint index)
+{
+    int socket = qt_safe_socket(AF_INET, SOCK_DGRAM, 0);
+    if (socket >= 0) {
+        struct ifreq req;
+        req.ifr_ifindex = index;
+
+        if (qt_safe_ioctl(socket, SIOCGIFNAME, &req) >= 0) {
+            qt_safe_close(socket);
+            return QString::fromLatin1(req.ifr_name);
+        }
+        qt_safe_close(socket);
+    }
+    return QString();
+}
+
+static QList<QNetworkInterfacePrivate *> getInterfaces(int sock, char *buf)
+{
+    QList<QNetworkInterfacePrivate *> result;
+
+    // request all links
+    struct {
+        struct nlmsghdr req;
+        struct ifinfomsg ifi;
+    } ifi_req;
+    memset(&ifi_req, 0, sizeof(ifi_req));
+
+    ifi_req.req.nlmsg_len = sizeof(ifi_req);
+    ifi_req.req.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+    ifi_req.req.nlmsg_type = RTM_GETLINK;
+
+    // parse the interfaces
+    processNetlinkRequest(sock, &ifi_req.req, buf, BufferSize, [&](ifinfomsg *ifi, size_t len) {
+        auto iface = new QNetworkInterfacePrivate;
+        iface->index = ifi->ifi_index;
+        iface->flags = convertFlags(ifi->ifi_flags);
+
+        // read attributes
+        auto rta = reinterpret_cast<struct rtattr *>(ifi + 1);
+        len -= sizeof(*ifi);
+        for ( ; RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
+            int payloadLen = RTA_PAYLOAD(rta);
+            auto payloadPtr = reinterpret_cast<char *>(RTA_DATA(rta));
+
+            switch (rta->rta_type) {
+            case IFLA_ADDRESS:      // link-level address
+                iface->hardwareAddress =
+                        iface->makeHwAddress(payloadLen, reinterpret_cast<uchar *>(payloadPtr));
+                break;
+
+            case IFLA_IFNAME:       // interface name
+                iface->name = QString::fromLatin1(payloadPtr, payloadLen - 1);
+                break;
+
+            case IFLA_OPERSTATE:    // operational state
+                if (*payloadPtr != IF_OPER_UNKNOWN) {
+                    // override the flag
+                    iface->flags &= ~QNetworkInterface::IsUp;
+                    if (*payloadPtr == IF_OPER_UP)
+                        iface->flags |= QNetworkInterface::IsUp;
+                }
+                break;
+            }
+        }
+
+        if (Q_UNLIKELY(iface->name.isEmpty())) {
+            qWarning("QNetworkInterface: found interface %d with no name", iface->index);
+            delete iface;
+        } else {
+            result.append(iface);
+        }
+    });
+    return result;
+}
+
+static void getAddresses(int sock, char *buf, QList<QNetworkInterfacePrivate *> &result)
+{
+    // request all addresses
+    struct {
+        struct nlmsghdr req;
+        struct ifaddrmsg ifa;
+    } ifa_req;
+    memset(&ifa_req, 0, sizeof(ifa_req));
+
+    ifa_req.req.nlmsg_len = sizeof(ifa_req);
+    ifa_req.req.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+    ifa_req.req.nlmsg_type = RTM_GETADDR;
+    ifa_req.req.nlmsg_seq = 1;
+
+    // parse the addresses
+    processNetlinkRequest(sock, &ifa_req.req, buf, BufferSize, [&](ifaddrmsg *ifa, size_t len) {
+        if (Q_UNLIKELY(ifa->ifa_family != AF_INET && ifa->ifa_family != AF_INET6)) {
+            // unknown address types
+            return;
+        }
+
+        // find the interface this is relevant to
+        QNetworkInterfacePrivate *iface = nullptr;
+        for (auto candidate : qAsConst(result)) {
+            if (candidate->index != int(ifa->ifa_index))
+                continue;
+            iface = candidate;
+            break;
+        }
+
+        if (Q_UNLIKELY(!iface)) {
+            qWarning("QNetworkInterface/AF_NETLINK: found unknown interface with index %d", ifa->ifa_index);
+            return;
+        }
+
+        QNetworkAddressEntry entry;
+        quint32 flags = ifa->ifa_flags;  // may be overwritten by IFA_FLAGS
+
+        auto makeAddress = [=](uchar *ptr, int len) {
+            QHostAddress addr;
+            if (ifa->ifa_family == AF_INET) {
+                Q_ASSERT(len == 4);
+                addr.setAddress(qFromBigEndian<quint32>(ptr));
+            } else {
+                Q_ASSERT(len == 16);
+                addr.setAddress(ptr);
+
+                // do we need a scope ID?
+                if (addr.isLinkLocal())
+                    addr.setScopeId(iface->name);
+            }
+            return addr;
+        };
+
+        // read attributes
+        auto rta = reinterpret_cast<struct rtattr *>(ifa + 1);
+        len -= sizeof(*ifa);
+        for ( ; RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
+            int payloadLen = RTA_PAYLOAD(rta);
+            auto payloadPtr = reinterpret_cast<uchar *>(RTA_DATA(rta));
+
+            switch (rta->rta_type) {
+            case IFA_ADDRESS:           // address
+                entry.setIp(makeAddress(payloadPtr, payloadLen));
+                break;
+
+            case IFA_BROADCAST:
+                Q_ASSERT(ifa->ifa_family == AF_INET);
+                entry.setBroadcast(makeAddress(payloadPtr, payloadLen));
+                break;
+
+            case IFA_FLAGS:
+                Q_ASSERT(payloadLen == 4);
+                flags = qFromUnaligned<quint32>(payloadPtr);
+                break;
+            }
+        }
+
+        // now handle flags
+        Q_UNUSED(flags);
+
+        if (!entry.ip().isNull()) {
+            entry.setPrefixLength(ifa->ifa_prefixlen);
+            iface->addressEntries.append(entry);
+        }
+    });
+}
+
+QList<QNetworkInterfacePrivate *> QNetworkInterfaceManager::scan()
+{
+    // open netlink socket
+    QList<QNetworkInterfacePrivate *> result;
+    NetlinkSocket sock(BufferSize);
+    if (Q_UNLIKELY(sock == -1))
+        return result;
+
+    QByteArray buffer(BufferSize, Qt::Uninitialized);
+    char *buf = buffer.data();
+
+    result = getInterfaces(sock, buf);
+    getAddresses(sock, buf, result);
+
+    return result;
+}
+
+QT_END_NAMESPACE
diff --git a/src/network/kernel/qnetworkinterface_unix.cpp b/src/network/kernel/qnetworkinterface_unix.cpp
index f8a33c395e..0b361810e8 100644
--- a/src/network/kernel/qnetworkinterface_unix.cpp
+++ b/src/network/kernel/qnetworkinterface_unix.cpp
@@ -41,34 +41,15 @@
 #include "qset.h"
 #include "qnetworkinterface.h"
 #include "qnetworkinterface_p.h"
+#include "qnetworkinterface_unix_p.h"
 #include "qalgorithms.h"
-#include "private/qnet_unix_p.h"
 
 #ifndef QT_NO_NETWORKINTERFACE
 
-#define IP_MULTICAST    // make AIX happy and define IFF_MULTICAST
-
-#include <sys/types.h>
-#include <sys/socket.h>
-
-#ifdef Q_OS_SOLARIS
-# include <sys/sockio.h>
-#endif
-#include <net/if.h>
-
-#ifndef QT_NO_IPV6IFNAME
-#include <net/if.h>
-#endif
-
 #if defined(QT_LINUXBASE)
 #  define QT_NO_GETIFADDRS
 #endif
 
-#ifdef Q_OS_HAIKU
-# include <sys/sockio.h>
-# define IFF_RUNNING 0x0001
-#endif
-
 #ifndef QT_NO_GETIFADDRS
 # include <ifaddrs.h>
 #endif
@@ -107,23 +88,6 @@ static QHostAddress addressFromSockaddr(sockaddr *sa, int ifindex = 0, const QSt
 
 }
 
-static QNetworkInterface::InterfaceFlags convertFlags(uint rawFlags)
-{
-    QNetworkInterface::InterfaceFlags flags = 0;
-    flags |= (rawFlags & IFF_UP) ? QNetworkInterface::IsUp : QNetworkInterface::InterfaceFlag(0);
-    flags |= (rawFlags & IFF_RUNNING) ? QNetworkInterface::IsRunning : QNetworkInterface::InterfaceFlag(0);
-    flags |= (rawFlags & IFF_BROADCAST) ? QNetworkInterface::CanBroadcast : QNetworkInterface::InterfaceFlag(0);
-    flags |= (rawFlags & IFF_LOOPBACK) ? QNetworkInterface::IsLoopBack : QNetworkInterface::InterfaceFlag(0);
-#ifdef IFF_POINTOPOINT //cygwin doesn't define IFF_POINTOPOINT
-    flags |= (rawFlags & IFF_POINTOPOINT) ? QNetworkInterface::IsPointToPoint : QNetworkInterface::InterfaceFlag(0);
-#endif
-
-#ifdef IFF_MULTICAST
-    flags |= (rawFlags & IFF_MULTICAST) ? QNetworkInterface::CanMulticast : QNetworkInterface::InterfaceFlag(0);
-#endif
-    return flags;
-}
-
 uint QNetworkInterfaceManager::interfaceIndexFromName(const QString &name)
 {
 #ifndef QT_NO_IPV6IFNAME
diff --git a/src/network/kernel/qnetworkinterface_unix_p.h b/src/network/kernel/qnetworkinterface_unix_p.h
new file mode 100644
index 0000000000..c085194e3c
--- /dev/null
+++ b/src/network/kernel/qnetworkinterface_unix_p.h
@@ -0,0 +1,102 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Copyright (C) 2017 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtNetwork module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QNETWORKINTERFACE_UNIX_P_H
+#define QNETWORKINTERFACE_UNIX_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. It exists purely as an
+// implementation detail. This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qnetworkinterface_p.h"
+#include "private/qnet_unix_p.h"
+
+#ifndef QT_NO_NETWORKINTERFACE
+
+#define IP_MULTICAST    // make AIX happy and define IFF_MULTICAST
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#ifdef Q_OS_SOLARIS
+#  include <sys/sockio.h>
+#endif
+#ifdef Q_OS_HAIKU
+#  include <sys/sockio.h>
+#  define IFF_RUNNING 0x0001
+#endif
+#if QT_CONFIG(linux_netlink)
+// Same as net/if.h but contains other things we need in
+// qnetworkinterface_linux.cpp.
+#  include <linux/if.h>
+#else
+#  include <net/if.h>
+#endif
+
+QT_BEGIN_NAMESPACE
+
+static QNetworkInterface::InterfaceFlags convertFlags(uint rawFlags)
+{
+    QNetworkInterface::InterfaceFlags flags = 0;
+    flags |= (rawFlags & IFF_UP) ? QNetworkInterface::IsUp : QNetworkInterface::InterfaceFlag(0);
+    flags |= (rawFlags & IFF_RUNNING) ? QNetworkInterface::IsRunning : QNetworkInterface::InterfaceFlag(0);
+    flags |= (rawFlags & IFF_BROADCAST) ? QNetworkInterface::CanBroadcast : QNetworkInterface::InterfaceFlag(0);
+    flags |= (rawFlags & IFF_LOOPBACK) ? QNetworkInterface::IsLoopBack : QNetworkInterface::InterfaceFlag(0);
+#ifdef IFF_POINTOPOINT //cygwin doesn't define IFF_POINTOPOINT
+    flags |= (rawFlags & IFF_POINTOPOINT) ? QNetworkInterface::IsPointToPoint : QNetworkInterface::InterfaceFlag(0);
+#endif
+
+#ifdef IFF_MULTICAST
+    flags |= (rawFlags & IFF_MULTICAST) ? QNetworkInterface::CanMulticast : QNetworkInterface::InterfaceFlag(0);
+#endif
+    return flags;
+}
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_NETWORKINTERFACE
+
+#endif // QNETWORKINTERFACE_UNIX_P_H