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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-secpoll.hh"
#ifndef DISABLE_SECPOLL
#include <vector>
#ifdef HAVE_LIBSODIUM
#include <sodium.h>
#endif /* HAVE_LIBSODIUM */
#include "dnsparser.hh"
#include "dolog.hh"
#include "iputils.hh"
#include "misc.hh"
#include "sstuff.hh"
#include "dnsdist.hh"
#include "dnsdist-random.hh"
#ifndef PACKAGEVERSION
#define PACKAGEVERSION PACKAGE_VERSION
#endif
static std::string getFirstTXTAnswer(const std::string& answer)
{
if (answer.size() <= sizeof(struct dnsheader)) {
throw std::runtime_error("Looking for a TXT record in an answer smaller than the DNS header");
}
const struct dnsheader* dh = reinterpret_cast<const struct dnsheader*>(answer.data());
PacketReader pr(answer);
uint16_t qdcount = ntohs(dh->qdcount);
uint16_t ancount = ntohs(dh->ancount);
DNSName rrname;
uint16_t rrtype;
uint16_t rrclass;
size_t idx = 0;
/* consume qd */
for(; idx < qdcount; idx++) {
rrname = pr.getName();
rrtype = pr.get16BitInt();
rrclass = pr.get16BitInt();
(void) rrtype;
(void) rrclass;
}
/* parse AN */
for (idx = 0; idx < ancount; idx++) {
string blob;
struct dnsrecordheader ah;
rrname = pr.getName();
pr.getDnsrecordheader(ah);
if (ah.d_type == QType::TXT) {
string txt;
pr.xfrText(txt);
return txt;
}
else {
pr.xfrBlob(blob);
}
}
throw std::runtime_error("No TXT record in answer");
}
static std::string getSecPollStatus(const std::string& queriedName, int timeout=2)
{
const DNSName sentName(queriedName);
std::vector<uint8_t> packet;
DNSPacketWriter pw(packet, sentName, QType::TXT);
pw.getHeader()->id = dnsdist::getRandomDNSID();
pw.getHeader()->rd = 1;
const auto& resolversForStub = getResolvers("/etc/resolv.conf");
for(const auto& dest : resolversForStub) {
Socket sock(dest.sin4.sin_family, SOCK_DGRAM);
sock.setNonBlocking();
sock.connect(dest);
sock.send(string(packet.begin(), packet.end()));
string reply;
int ret = waitForData(sock.getHandle(), timeout, 0);
if (ret < 0) {
if (g_verbose) {
warnlog("Error while waiting for the secpoll response from stub resolver %s: %d", dest.toString(), ret);
}
continue;
}
else if (ret == 0) {
if (g_verbose) {
warnlog("Timeout while waiting for the secpoll response from stub resolver %s", dest.toString());
}
continue;
}
try {
sock.read(reply);
}
catch(const std::exception& e) {
if (g_verbose) {
warnlog("Error while reading for the secpoll response from stub resolver %s: %s", dest.toString(), e.what());
}
continue;
}
if (reply.size() <= sizeof(struct dnsheader)) {
if (g_verbose) {
warnlog("Too short answer of size %d received from the secpoll stub resolver %s", reply.size(), dest.toString());
}
continue;
}
struct dnsheader d;
memcpy(&d, reply.c_str(), sizeof(d));
if (d.id != pw.getHeader()->id) {
if (g_verbose) {
warnlog("Invalid ID (%d / %d) received from the secpoll stub resolver %s", d.id, pw.getHeader()->id, dest.toString());
}
continue;
}
if (d.rcode != RCode::NoError) {
if (g_verbose) {
warnlog("Response code '%s' received from the secpoll stub resolver %s for '%s'", RCode::to_s(d.rcode), dest.toString(), queriedName);
}
/* no need to try another resolver if the domain does not exist */
if (d.rcode == RCode::NXDomain) {
throw std::runtime_error("Unable to get a valid Security Status update");
}
continue;
}
if (ntohs(d.qdcount) != 1 || ntohs(d.ancount) != 1) {
if (g_verbose) {
warnlog("Invalid answer (qdcount %d / ancount %d) received from the secpoll stub resolver %s", ntohs(d.qdcount), ntohs(d.ancount), dest.toString());
}
continue;
}
uint16_t receivedType;
uint16_t receivedClass;
DNSName receivedName(reply.c_str(), reply.size(), sizeof(dnsheader), false, &receivedType, &receivedClass);
if (receivedName != sentName || receivedType != QType::TXT || receivedClass != QClass::IN) {
if (g_verbose) {
warnlog("Invalid answer, either the qname (%s / %s), qtype (%s / %s) or qclass (%s / %s) does not match, received from the secpoll stub resolver %s", receivedName, sentName, QType(receivedType).toString(), QType(QType::TXT).toString(), QClass(receivedClass).toString(), QClass::IN.toString(), dest.toString());
}
continue;
}
return getFirstTXTAnswer(reply);
}
throw std::runtime_error("Unable to get a valid Security Status update");
}
static bool g_secPollDone{false};
std::string g_secPollSuffix{"secpoll.powerdns.com."};
time_t g_secPollInterval{3600};
void doSecPoll(const std::string& suffix)
{
if (suffix.empty()) {
return;
}
const std::string pkgv(PACKAGEVERSION);
bool releaseVersion = std::count(pkgv.begin(), pkgv.end(), '.') == 2;
const std::string version = "dnsdist-" + pkgv;
std::string queriedName = version.substr(0, 63) + ".security-status." + suffix;
if (*queriedName.rbegin() != '.') {
queriedName += '.';
}
boost::replace_all(queriedName, "+", "_");
boost::replace_all(queriedName, "~", "_");
try {
std::string status = getSecPollStatus(queriedName);
pair<string, string> split = splitField(unquotify(status), ' ');
int securityStatus = std::stoi(split.first);
std::string securityMessage = split.second;
if(securityStatus == 1 && !g_secPollDone) {
warnlog("Polled security status of version %s at startup, no known issues reported: %s", std::string(VERSION), securityMessage);
}
if(securityStatus == 2) {
errlog("PowerDNS DNSDist Security Update Recommended: %s", securityMessage);
}
else if(securityStatus == 3) {
errlog("PowerDNS DNSDist Security Update Mandatory: %s", securityMessage);
}
g_stats.securityStatus = securityStatus;
g_secPollDone = true;
return;
}
catch(const std::exception& e) {
if (releaseVersion) {
warnlog("Error while retrieving the security update for version %s: %s", version, e.what());
}
else if (!g_secPollDone) {
infolog("Error while retrieving the security update for version %s: %s", version, e.what());
}
}
if (releaseVersion) {
warnlog("Failed to retrieve security status update for '%s' on %s", pkgv, queriedName);
}
else if (!g_secPollDone) {
infolog("Not validating response for security status update, this is a non-release version.");
/* for non-released versions, there is no use sending the same message several times,
let's just accept that there will be no security polling for this exact version */
g_secPollDone = true;
}
}
#endif /* DISABLE_SECPOLL */
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