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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-svc.hh"
#include "dnsdist.hh"
#include "dnsdist-ecs.hh"
#include "dnsdist-lua.hh"
#include "dnswriter.hh"
#include "svc-records.hh"
bool generateSVCPayload(std::vector<uint8_t>& payload, uint16_t priority, const DNSName& target, const std::set<uint16_t>& mandatoryParams, const std::vector<std::string>& alpns, bool noDefaultAlpn, std::optional<uint16_t> port, const std::string& ech, const std::vector<ComboAddress>& ipv4hints, const std::vector<ComboAddress>& ipv6hints, const std::vector<std::pair<uint16_t, std::string>>& additionalParams)
{
// this is an _ordered_ set and the comparison operator is properly defined,
// so the parameters will be ordered as defined in the RFC
std::set<SvcParam> params;
if (!mandatoryParams.empty()) {
std::set<SvcParam::SvcParamKey> mandatoryKeys;
for (const auto& entry : mandatoryParams) {
mandatoryKeys.insert(static_cast<SvcParam::SvcParamKey>(entry));
}
params.insert({SvcParam::SvcParamKey::mandatory, std::move(mandatoryKeys)});
}
if (!alpns.empty()) {
params.insert({SvcParam::SvcParamKey::alpn, std::vector<std::string>(alpns)});
}
if (noDefaultAlpn) {
params.insert({SvcParam::SvcParamKey::no_default_alpn});
}
if (port) {
params.insert({SvcParam::SvcParamKey::port, *port});
}
if (!ipv4hints.empty()) {
params.insert({SvcParam::SvcParamKey::ipv4hint, std::vector<ComboAddress>(ipv4hints)});
}
if (!ech.empty()) {
params.insert({SvcParam::SvcParamKey::ech, ech});
}
if (!ipv6hints.empty()) {
params.insert({SvcParam::SvcParamKey::ipv6hint, std::vector<ComboAddress>(ipv6hints)});
}
for (const auto& param : additionalParams) {
params.insert({static_cast<SvcParam::SvcParamKey>(param.first), param.second});
}
if (priority == 0 && params.size() != 0) {
return false;
}
payload.clear();
/* we will remove the header, question and record header parts later */
DNSPacketWriter pw(payload, g_rootdnsname, QType::A, QClass::IN, 0);
pw.startRecord(g_rootdnsname, QType::A, 60, QClass::IN, DNSResourceRecord::ANSWER, false);
size_t offset = pw.size();
pw.xfr16BitInt(priority);
pw.xfrName(target, false, true);
pw.xfrSvcParamKeyVals(params);
pw.commit();
if (payload.size() <= offset) {
return false;
}
payload.erase(payload.begin(), payload.begin() + offset);
return true;
}
bool generateSVCPayload(std::vector<uint8_t>& payload, const SVCRecordParameters& parameters)
{
return generateSVCPayload(payload, parameters.priority, parameters.target, parameters.mandatoryParams, parameters.alpns, parameters.noDefaultAlpn, parameters.port, parameters.ech, parameters.ipv4hints, parameters.ipv6hints, parameters.additionalParams);
}
struct SVCRecordParameters parseSVCParameters(const svcParamsLua_t& params)
{
struct SVCRecordParameters parameters;
for (const auto& p : params) {
if (p.first == "mandatory") {
for (auto const& entry : boost::get<std::vector<std::pair<int, std::string>>>(p.second)) {
parameters.mandatoryParams.insert(SvcParam::keyFromString(entry.second));
}
}
else if (p.first == "alpn") {
for (auto const& entry : boost::get<std::vector<std::pair<int, std::string>>>(p.second)) {
parameters.alpns.push_back(entry.second);
}
}
else if (p.first == "noDefaultAlpn") {
parameters.noDefaultAlpn = boost::get<bool>(p.second);
}
else if (p.first == "port") {
parameters.port = boost::get<uint16_t>(p.second);
}
else if (p.first == "ipv4hint") {
for (auto const& entry : boost::get<std::vector<std::pair<int, std::string>>>(p.second)) {
parameters.ipv4hints.push_back(ComboAddress(entry.second));
}
}
else if (p.first == "ech") {
parameters.ech = boost::get<std::string>(p.second);
}
else if (p.first == "ipv6hint") {
for (auto const& entry : boost::get<std::vector<std::pair<int, std::string>>>(p.second)) {
parameters.ipv6hints.push_back(ComboAddress(entry.second));
}
}
else {
parameters.additionalParams.push_back({SvcParam::keyFromString(p.first), boost::get<std::string>(p.second)});
}
}
return parameters;
}
namespace dnsdist::svc
{
bool generateSVCResponse(DNSQuestion& dnsQuestion, const std::vector<std::vector<uint8_t>>& svcRecordPayloads, const std::set<std::pair<DNSName, ComboAddress>>& additionals4, const std::set<std::pair<DNSName, ComboAddress>>& additionals6, const ResponseConfig& responseConfig)
{
/* it will likely be a bit bigger than that because of additionals */
size_t totalPayloadsSize = 0;
for (const auto& payload : svcRecordPayloads) {
totalPayloadsSize += payload.size();
}
const auto numberOfRecords = svcRecordPayloads.size();
const auto qnameWireLength = dnsQuestion.ids.qname.wirelength();
if (dnsQuestion.getMaximumSize() < (sizeof(dnsheader) + qnameWireLength + 4 + numberOfRecords * 12 /* recordstart */ + totalPayloadsSize)) {
return false;
}
PacketBuffer newPacket;
newPacket.reserve(sizeof(dnsheader) + qnameWireLength + 4 + numberOfRecords * 12 /* recordstart */ + totalPayloadsSize);
GenericDNSPacketWriter<PacketBuffer> packetWriter(newPacket, dnsQuestion.ids.qname, dnsQuestion.ids.qtype);
for (const auto& payload : svcRecordPayloads) {
packetWriter.startRecord(dnsQuestion.ids.qname, dnsQuestion.ids.qtype, responseConfig.ttl);
packetWriter.xfrBlob(payload);
packetWriter.commit();
}
if (newPacket.size() < dnsQuestion.getMaximumSize()) {
for (const auto& additional : additionals4) {
packetWriter.startRecord(additional.first.isRoot() ? dnsQuestion.ids.qname : additional.first, QType::A, responseConfig.ttl, QClass::IN, DNSResourceRecord::ADDITIONAL);
packetWriter.xfrCAWithoutPort(4, additional.second);
packetWriter.commit();
}
}
if (newPacket.size() < dnsQuestion.getMaximumSize()) {
for (const auto& additional : additionals6) {
packetWriter.startRecord(additional.first.isRoot() ? dnsQuestion.ids.qname : additional.first, QType::AAAA, responseConfig.ttl, QClass::IN, DNSResourceRecord::ADDITIONAL);
packetWriter.xfrCAWithoutPort(6, additional.second);
packetWriter.commit();
}
}
if (g_addEDNSToSelfGeneratedResponses && queryHasEDNS(dnsQuestion)) {
bool dnssecOK = ((getEDNSZ(dnsQuestion) & EDNS_HEADER_FLAG_DO) != 0);
packetWriter.addOpt(g_PayloadSizeSelfGenAnswers, 0, dnssecOK ? EDNS_HEADER_FLAG_DO : 0);
packetWriter.commit();
}
if (newPacket.size() >= dnsQuestion.getMaximumSize()) {
/* sorry! */
return false;
}
packetWriter.getHeader()->id = dnsQuestion.getHeader()->id;
packetWriter.getHeader()->qr = true; // for good measure
setResponseHeadersFromConfig(*packetWriter.getHeader(), responseConfig);
dnsQuestion.getMutableData() = std::move(newPacket);
return true;
}
bool generateSVCResponse(DNSQuestion& dnsQuestion, uint32_t ttl, const std::vector<SVCRecordParameters>& parameters)
{
std::vector<std::vector<uint8_t>> payloads;
std::set<std::pair<DNSName, ComboAddress>> additionals4;
std::set<std::pair<DNSName, ComboAddress>> additionals6;
ResponseConfig responseConfig;
responseConfig.setAA = true;
responseConfig.ttl = ttl;
payloads.reserve(parameters.size());
for (const auto& parameter : parameters) {
std::vector<uint8_t> payload;
if (!generateSVCPayload(payload, parameter)) {
throw std::runtime_error("Unable to generate a valid SVC record from the supplied parameters");
}
payloads.push_back(std::move(payload));
for (const auto& hint : parameter.ipv4hints) {
additionals4.insert({parameter.target, ComboAddress(hint)});
}
for (const auto& hint : parameter.ipv6hints) {
additionals6.insert({parameter.target, ComboAddress(hint)});
}
}
return generateSVCResponse(dnsQuestion, payloads, additionals4, additionals6, responseConfig);
}
}
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