1 files changed, 248 insertions, 0 deletions
diff --git a/dnsdist-secpoll.cc b/dnsdist-secpoll.cc
new file mode 100644
index 0000000..eb38d35
--- /dev/null
+++ b/dnsdist-secpoll.cc
@@ -0,0 +1,248 @@
+/*
+ * 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 */