amnezia-client/client/platforms/windows/daemon/windowsroutemonitor.cpp
Mykola Baibuz 07c38e9b6c
WireGuard rework for MacOS and Windows (#314)
WireGuard rework for MacOS and Windows
2023-09-14 17:44:17 +01:00

317 lines
10 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "windowsroutemonitor.h"
#include <QScopeGuard>
#include "leakdetector.h"
#include "logger.h"
namespace {
Logger logger("WindowsRouteMonitor");
}; // namespace
// Called by the kernel on route changes - perform some basic filtering and
// invoke the routeChanged slot to do the real work.
static void routeChangeCallback(PVOID context, PMIB_IPFORWARD_ROW2 row,
MIB_NOTIFICATION_TYPE type) {
WindowsRouteMonitor* monitor = (WindowsRouteMonitor*)context;
Q_UNUSED(type);
// Ignore host route changes, and unsupported protocols.
if (row->DestinationPrefix.Prefix.si_family == AF_INET6) {
if (row->DestinationPrefix.PrefixLength >= 128) {
return;
}
} else if (row->DestinationPrefix.Prefix.si_family == AF_INET) {
if (row->DestinationPrefix.PrefixLength >= 32) {
return;
}
} else {
return;
}
if (monitor->getLuid() != row->InterfaceLuid.Value) {
QMetaObject::invokeMethod(monitor, "routeChanged", Qt::QueuedConnection);
}
}
// Perform prefix matching comparison on IP addresses in host order.
static int prefixcmp(const void* a, const void* b, size_t bits) {
size_t bytes = bits / 8;
if (bytes > 0) {
int diff = memcmp(a, b, bytes);
if (diff != 0) {
return diff;
}
}
if (bits % 8) {
quint8 avalue = *((const quint8*)a + bytes) >> (8 - bits % 8);
quint8 bvalue = *((const quint8*)b + bytes) >> (8 - bits % 8);
return avalue - bvalue;
}
return 0;
}
WindowsRouteMonitor::WindowsRouteMonitor(QObject* parent) : QObject(parent) {
MZ_COUNT_CTOR(WindowsRouteMonitor);
logger.debug() << "WindowsRouteMonitor created.";
NotifyRouteChange2(AF_INET, routeChangeCallback, this, FALSE, &m_routeHandle);
}
WindowsRouteMonitor::~WindowsRouteMonitor() {
MZ_COUNT_DTOR(WindowsRouteMonitor);
CancelMibChangeNotify2(m_routeHandle);
flushExclusionRoutes();
logger.debug() << "WindowsRouteMonitor destroyed.";
}
void WindowsRouteMonitor::updateValidInterfaces(int family) {
PMIB_IPINTERFACE_TABLE table;
DWORD result = GetIpInterfaceTable(family, &table);
if (result != NO_ERROR) {
logger.warning() << "Failed to retrive interface table." << result;
return;
}
auto guard = qScopeGuard([&] { FreeMibTable(table); });
// Flush the list of interfaces that are valid for routing.
if ((family == AF_INET) || (family == AF_UNSPEC)) {
m_validInterfacesIpv4.clear();
}
if ((family == AF_INET6) || (family == AF_UNSPEC)) {
m_validInterfacesIpv6.clear();
}
// Rebuild the list of interfaces that are valid for routing.
for (ULONG i = 0; i < table->NumEntries; i++) {
MIB_IPINTERFACE_ROW* row = &table->Table[i];
if (row->InterfaceLuid.Value == m_luid) {
continue;
}
if (!row->Connected) {
continue;
}
if (row->Family == AF_INET) {
logger.debug() << "Interface" << row->InterfaceIndex
<< "is valid for IPv4 routing";
m_validInterfacesIpv4.append(row->InterfaceLuid.Value);
}
if (row->Family == AF_INET6) {
logger.debug() << "Interface" << row->InterfaceIndex
<< "is valid for IPv6 routing";
m_validInterfacesIpv6.append(row->InterfaceLuid.Value);
}
}
}
void WindowsRouteMonitor::updateExclusionRoute(MIB_IPFORWARD_ROW2* data,
void* ptable) {
PMIB_IPFORWARD_TABLE2 table = reinterpret_cast<PMIB_IPFORWARD_TABLE2>(ptable);
SOCKADDR_INET nexthop = {0};
quint64 bestLuid = 0;
int bestMatch = -1;
ULONG bestMetric = ULONG_MAX;
nexthop.si_family = data->DestinationPrefix.Prefix.si_family;
for (ULONG i = 0; i < table->NumEntries; i++) {
MIB_IPFORWARD_ROW2* row = &table->Table[i];
// Ignore routes into the VPN interface.
if (row->InterfaceLuid.Value == m_luid) {
continue;
}
// Ignore host routes, and shorter potential matches.
if (row->DestinationPrefix.PrefixLength >=
data->DestinationPrefix.PrefixLength) {
continue;
}
if (row->DestinationPrefix.PrefixLength < bestMatch) {
continue;
}
// Check if the routing table entry matches the destination.
if (data->DestinationPrefix.Prefix.si_family == AF_INET6) {
if (row->DestinationPrefix.Prefix.Ipv6.sin6_family != AF_INET6) {
continue;
}
if (!m_validInterfacesIpv6.contains(row->InterfaceLuid.Value)) {
continue;
}
if (prefixcmp(&data->DestinationPrefix.Prefix.Ipv6.sin6_addr,
&row->DestinationPrefix.Prefix.Ipv6.sin6_addr,
row->DestinationPrefix.PrefixLength) != 0) {
continue;
}
} else if (data->DestinationPrefix.Prefix.si_family == AF_INET) {
if (row->DestinationPrefix.Prefix.Ipv4.sin_family != AF_INET) {
continue;
}
if (!m_validInterfacesIpv4.contains(row->InterfaceLuid.Value)) {
continue;
}
if (prefixcmp(&data->DestinationPrefix.Prefix.Ipv4.sin_addr,
&row->DestinationPrefix.Prefix.Ipv4.sin_addr,
row->DestinationPrefix.PrefixLength) != 0) {
continue;
}
} else {
// Unsupported destination address family.
continue;
}
// Prefer routes with lower metric if we find multiple matches
// with the same prefix length.
if ((row->DestinationPrefix.PrefixLength == bestMatch) &&
(row->Metric >= bestMetric)) {
continue;
}
// If we got here, then this is the longest prefix match so far.
memcpy(&nexthop, &row->NextHop, sizeof(SOCKADDR_INET));
bestLuid = row->InterfaceLuid.Value;
bestMatch = row->DestinationPrefix.PrefixLength;
bestMetric = row->Metric;
}
// If neither the interface nor next-hop have changed, then do nothing.
if ((data->InterfaceLuid.Value) == bestLuid &&
memcmp(&nexthop, &data->NextHop, sizeof(SOCKADDR_INET)) == 0) {
return;
}
// Update the routing table entry.
if (data->InterfaceLuid.Value != 0) {
DWORD result = DeleteIpForwardEntry2(data);
if ((result != NO_ERROR) && (result != ERROR_NOT_FOUND)) {
logger.error() << "Failed to delete route:" << result;
}
}
data->InterfaceLuid.Value = bestLuid;
memcpy(&data->NextHop, &nexthop, sizeof(SOCKADDR_INET));
if (data->InterfaceLuid.Value != 0) {
DWORD result = CreateIpForwardEntry2(data);
if (result != NO_ERROR) {
logger.error() << "Failed to update route:" << result;
}
}
}
bool WindowsRouteMonitor::addExclusionRoute(const IPAddress& prefix) {
logger.debug() << "Adding exclusion route for"
<< logger.sensitive(prefix.toString());
if (m_exclusionRoutes.contains(prefix)) {
logger.warning() << "Exclusion route already exists";
return false;
}
// Allocate and initialize the MIB routing table row.
MIB_IPFORWARD_ROW2* data = new MIB_IPFORWARD_ROW2;
InitializeIpForwardEntry(data);
if (prefix.address().protocol() == QAbstractSocket::IPv6Protocol) {
Q_IPV6ADDR buf = prefix.address().toIPv6Address();
memcpy(&data->DestinationPrefix.Prefix.Ipv6.sin6_addr, &buf, sizeof(buf));
data->DestinationPrefix.Prefix.Ipv6.sin6_family = AF_INET6;
data->DestinationPrefix.PrefixLength = prefix.prefixLength();
} else {
quint32 buf = prefix.address().toIPv4Address();
data->DestinationPrefix.Prefix.Ipv4.sin_addr.s_addr = htonl(buf);
data->DestinationPrefix.Prefix.Ipv4.sin_family = AF_INET;
data->DestinationPrefix.PrefixLength = prefix.prefixLength();
}
data->NextHop.si_family = data->DestinationPrefix.Prefix.si_family;
// Set the rest of the flags for a static route.
data->ValidLifetime = 0xffffffff;
data->PreferredLifetime = 0xffffffff;
data->Metric = 0;
data->Protocol = MIB_IPPROTO_NETMGMT;
data->Loopback = false;
data->AutoconfigureAddress = false;
data->Publish = false;
data->Immortal = false;
data->Age = 0;
PMIB_IPFORWARD_TABLE2 table;
int family;
if (prefix.address().protocol() == QAbstractSocket::IPv6Protocol) {
family = AF_INET6;
} else {
family = AF_INET;
}
DWORD result = GetIpForwardTable2(family, &table);
if (result != NO_ERROR) {
logger.error() << "Failed to fetch routing table:" << result;
delete data;
return false;
}
updateValidInterfaces(family);
updateExclusionRoute(data, table);
FreeMibTable(table);
m_exclusionRoutes[prefix] = data;
return true;
}
bool WindowsRouteMonitor::deleteExclusionRoute(const IPAddress& prefix) {
logger.debug() << "Deleting exclusion route for"
<< logger.sensitive(prefix.address().toString());
for (;;) {
MIB_IPFORWARD_ROW2* data = m_exclusionRoutes.take(prefix);
if (data == nullptr) {
break;
}
DWORD result = DeleteIpForwardEntry2(data);
if ((result != ERROR_NOT_FOUND) && (result != NO_ERROR)) {
logger.error() << "Failed to delete route to"
<< logger.sensitive(prefix.toString())
<< "result:" << result;
}
delete data;
}
return true;
}
void WindowsRouteMonitor::flushExclusionRoutes() {
for (auto i = m_exclusionRoutes.begin(); i != m_exclusionRoutes.end(); i++) {
MIB_IPFORWARD_ROW2* data = i.value();
DWORD result = DeleteIpForwardEntry2(data);
if ((result != ERROR_NOT_FOUND) && (result != NO_ERROR)) {
logger.error() << "Failed to delete route to"
<< logger.sensitive(i.key().toString())
<< "result:" << result;
}
delete data;
}
m_exclusionRoutes.clear();
}
void WindowsRouteMonitor::routeChanged() {
logger.debug() << "Routes changed";
PMIB_IPFORWARD_TABLE2 table;
DWORD result = GetIpForwardTable2(AF_UNSPEC, &table);
if (result != NO_ERROR) {
logger.error() << "Failed to fetch routing table:" << result;
return;
}
updateValidInterfaces(AF_UNSPEC);
for (MIB_IPFORWARD_ROW2* data : m_exclusionRoutes) {
updateExclusionRoute(data, table);
}
FreeMibTable(table);
}