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/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "dnsdist.hh"
#include "dnsdist-xsk.hh"
#ifdef HAVE_XSK
#include <sys/poll.h>
#include "dolog.hh"
#include "dnsdist-metrics.hh"
#include "dnsdist-proxy-protocol.hh"
#include "threadname.hh"
#include "xsk.hh"
namespace dnsdist::xsk
{
std::vector<std::shared_ptr<XskSocket>> g_xsk;
void XskResponderThread(std::shared_ptr<DownstreamState> dss, std::shared_ptr<XskWorker> xskInfo)
{
try {
setThreadName("dnsdist/XskResp");
auto localRespRuleActions = g_respruleactions.getLocal();
auto localCacheInsertedRespRuleActions = g_cacheInsertedRespRuleActions.getLocal();
auto pollfds = getPollFdsForWorker(*xskInfo);
while (!dss->isStopped()) {
poll(pollfds.data(), pollfds.size(), -1);
bool needNotify = false;
if ((pollfds[0].revents & POLLIN) != 0) {
needNotify = true;
xskInfo->cleanSocketNotification();
xskInfo->processIncomingFrames([&](XskPacket& packet) {
if (packet.getDataLen() < sizeof(dnsheader)) {
xskInfo->markAsFree(packet);
return;
}
const dnsheader_aligned dnsHeader(packet.getPayloadData());
const auto queryId = dnsHeader->id;
auto ids = dss->getState(queryId);
if (ids) {
if (!ids->isXSK()) {
dss->restoreState(queryId, std::move(*ids));
ids = std::nullopt;
}
}
if (!ids) {
xskInfo->markAsFree(packet);
return;
}
auto response = packet.clonePacketBuffer();
if (response.size() > packet.getCapacity()) {
/* fallback to sending the packet via normal socket */
ids->xskPacketHeader.clear();
}
if (!processResponderPacket(dss, response, *localRespRuleActions, *localCacheInsertedRespRuleActions, std::move(*ids))) {
xskInfo->markAsFree(packet);
vinfolog("XSK packet dropped because processResponderPacket failed");
return;
}
if (response.size() > packet.getCapacity()) {
/* fallback to sending the packet via normal socket */
sendUDPResponse(ids->cs->udpFD, response, ids->delayMsec, ids->hopLocal, ids->hopRemote);
infolog("XSK packet falling back because packet is too large");
xskInfo->markAsFree(packet);
return;
}
packet.setHeader(ids->xskPacketHeader);
if (!packet.setPayload(response)) {
infolog("Unable to set XSK payload !");
}
if (ids->delayMsec > 0) {
packet.addDelay(ids->delayMsec);
}
packet.updatePacket();
xskInfo->pushToSendQueue(packet);
});
}
if (needNotify) {
xskInfo->notifyXskSocket();
}
}
}
catch (const std::exception& e) {
errlog("XSK responder thread died because of exception: %s", e.what());
}
catch (const PDNSException& e) {
errlog("XSK responder thread died because of PowerDNS exception: %s", e.reason);
}
catch (...) {
errlog("XSK responder thread died because of an exception: %s", "unknown");
}
}
bool XskIsQueryAcceptable(const XskPacket& packet, ClientState& clientState, LocalHolders& holders, bool& expectProxyProtocol)
{
const auto& from = packet.getFromAddr();
expectProxyProtocol = expectProxyProtocolFrom(from);
if (!holders.acl->match(from) && !expectProxyProtocol) {
vinfolog("Query from %s dropped because of ACL", from.toStringWithPort());
++dnsdist::metrics::g_stats.aclDrops;
return false;
}
clientState.queries++;
++dnsdist::metrics::g_stats.queries;
return true;
}
void XskRouter(std::shared_ptr<XskSocket> xsk)
{
setThreadName("dnsdist/XskRouter");
uint32_t failed = 0;
// packets to be submitted for sending
vector<XskPacket> fillInTx;
const auto& fds = xsk->getDescriptors();
// list of workers that need to be notified
std::set<int> needNotify;
while (true) {
try {
auto ready = xsk->wait(-1);
// descriptor 0 gets incoming AF_XDP packets
if ((fds.at(0).revents & POLLIN) != 0) {
auto packets = xsk->recv(64, &failed);
dnsdist::metrics::g_stats.nonCompliantQueries += failed;
for (auto& packet : packets) {
const auto dest = packet.getToAddr();
auto worker = xsk->getWorkerByDestination(dest);
if (!worker) {
xsk->markAsFree(packet);
continue;
}
worker->pushToProcessingQueue(packet);
needNotify.insert(worker->workerWaker.getHandle());
}
for (auto socket : needNotify) {
uint64_t value = 1;
auto written = write(socket, &value, sizeof(value));
if (written != sizeof(value)) {
// oh, well, the worker is clearly overloaded
// but there is nothing we can do about it,
// and hopefully the queue will be processed eventually
}
}
needNotify.clear();
ready--;
}
for (size_t fdIndex = 1; fdIndex < fds.size() && ready > 0; fdIndex++) {
if ((fds.at(fdIndex).revents & POLLIN) != 0) {
ready--;
const auto& info = xsk->getWorkerByDescriptor(fds.at(fdIndex).fd);
info->processOutgoingFrames([&](XskPacket& packet) {
if ((packet.getFlags() & XskPacket::UPDATE) == 0) {
xsk->markAsFree(packet);
return;
}
if ((packet.getFlags() & XskPacket::DELAY) != 0) {
xsk->pushDelayed(packet);
return;
}
fillInTx.push_back(packet);
});
info->cleanWorkerNotification();
}
}
xsk->pickUpReadyPacket(fillInTx);
xsk->recycle(4096);
xsk->fillFq();
xsk->send(fillInTx);
}
catch (...) {
vinfolog("Exception in XSK router loop");
}
}
}
void XskClientThread(ClientState* clientState)
{
setThreadName("dnsdist/xskClient");
auto xskInfo = clientState->xskInfo;
LocalHolders holders;
for (;;) {
while (!xskInfo->hasIncomingFrames()) {
xskInfo->waitForXskSocket();
}
xskInfo->processIncomingFrames([&](XskPacket& packet) {
if (XskProcessQuery(*clientState, holders, packet)) {
packet.updatePacket();
xskInfo->pushToSendQueue(packet);
}
else {
xskInfo->markAsFree(packet);
}
});
xskInfo->notifyXskSocket();
}
}
static std::string getDestinationMap(bool isV6)
{
return !isV6 ? "/sys/fs/bpf/dnsdist/xsk-destinations-v4" : "/sys/fs/bpf/dnsdist/xsk-destinations-v6";
}
void addDestinationAddress(const ComboAddress& addr)
{
auto map = getDestinationMap(addr.isIPv6());
XskSocket::addDestinationAddress(map, addr);
}
void removeDestinationAddress(const ComboAddress& addr)
{
auto map = getDestinationMap(addr.isIPv6());
XskSocket::removeDestinationAddress(map, addr);
}
void clearDestinationAddresses()
{
auto map = getDestinationMap(false);
XskSocket::clearDestinationMap(map, false);
map = getDestinationMap(true);
XskSocket::clearDestinationMap(map, true);
}
}
#endif /* HAVE_XSK */
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