Adding upstream version 2.4.1.upstream/2.4.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 987 insertions, 0 deletions

diff --git a/src/lib/d2srv/testutils/nc_test_utils.cc b/src/lib/d2srv/testutils/nc_test_utils.cc
new file mode 100644
index 0000000..3903535
--- /dev/null
+++ b/src/lib/d2srv/testutils/nc_test_utils.cc
@@ -0,0 +1,987 @@
+// Copyright (C) 2013-2021 Internet Systems Consortium, Inc. ("ISC")
+//
+// 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 <config.h>
+#include <asiolink/asio_wrapper.h>
+#include <asiolink/udp_endpoint.h>
+#include <d2srv/d2_cfg_mgr.h>
+#include <d2srv/testutils/nc_test_utils.h>
+#include <dns/messagerenderer.h>
+#include <dns/opcode.h>
+#include <util/encode/base64.h>
+
+#include <gtest/gtest.h>
+
+using namespace std;
+using namespace isc;
+using namespace isc::d2;
+namespace ph = std::placeholders;
+
+namespace isc {
+namespace d2 {
+
+const char* valid_d2_config = "{ "
+                        "\"ip-address\" : \"127.0.0.1\" , "
+                        "\"port\" : 5031, "
+                        "\"tsig-keys\": ["
+                        "{ \"name\": \"d2_key.example.com\" , "
+                        "   \"algorithm\": \"HMAC-MD5\" ,"
+                        "   \"secret\": \"LSWXnfkKZjdPJI5QxlpnfQ==\" "
+                        "} ],"
+                        "\"forward-ddns\" : {"
+                        "\"ddns-domains\": [ "
+                        "{ \"name\": \"example.com.\" , "
+                        "  \"key-name\": \"d2_key.example.com\" , "
+                        "  \"dns-servers\" : [ "
+                        "  { \"ip-address\": \"127.0.0.101\" } "
+                        "] } ] }, "
+                        "\"reverse-ddns\" : {"
+                        "\"ddns-domains\": [ "
+                        "{ \"name\": \" 0.168.192.in.addr.arpa.\" , "
+                        "  \"key-name\": \"d2_key.example.com\" , "
+                        "  \"dns-servers\" : [ "
+                        "  { \"ip-address\": \"127.0.0.101\" , "
+                        "    \"port\": 100 } ] } "
+                        "] } }";
+
+
+const char* TEST_DNS_SERVER_IP = "127.0.0.1";
+size_t TEST_DNS_SERVER_PORT = 5301;
+
+//const bool HAS_RDATA = true;
+const bool NO_RDATA = false;
+
+//*************************** FauxServer class ***********************
+
+FauxServer::FauxServer(asiolink::IOService& io_service,
+                       asiolink::IOAddress& address, size_t port)
+    :io_service_(io_service), address_(address), port_(port),
+     server_socket_(), receive_pending_(false), perpetual_receive_(true),
+     tsig_key_() {
+
+    server_socket_.reset(new boost::asio::ip::udp::socket(io_service_.get_io_service(),
+                                                   boost::asio::ip::udp::v4()));
+    server_socket_->set_option(boost::asio::socket_base::reuse_address(true));
+
+    isc::asiolink::UDPEndpoint endpoint(address_, port_);
+    server_socket_->bind(endpoint.getASIOEndpoint());
+}
+
+FauxServer::FauxServer(asiolink::IOService& io_service,
+                       DnsServerInfo& server)
+    :io_service_(io_service), address_(server.getIpAddress()),
+     port_(server.getPort()), server_socket_(), receive_pending_(false),
+     perpetual_receive_(true), tsig_key_() {
+    server_socket_.reset(new boost::asio::ip::udp::socket(io_service_.get_io_service(),
+                                                   boost::asio::ip::udp::v4()));
+    server_socket_->set_option(boost::asio::socket_base::reuse_address(true));
+    isc::asiolink::UDPEndpoint endpoint(address_, port_);
+    server_socket_->bind(endpoint.getASIOEndpoint());
+}
+
+
+FauxServer::~FauxServer() {
+}
+
+void
+FauxServer::receive (const ResponseMode& response_mode,
+                     const dns::Rcode& response_rcode) {
+    if (receive_pending_) {
+        return;
+    }
+
+    receive_pending_ = true;
+    server_socket_->async_receive_from(boost::asio::buffer(receive_buffer_,
+                                                    sizeof(receive_buffer_)),
+                                       remote_,
+                                       std::bind(&FauxServer::requestHandler,
+                                                 this, ph::_1, ph::_2,
+                                                 response_mode,
+                                                 response_rcode));
+}
+
+void
+FauxServer::requestHandler(const boost::system::error_code& error,
+                           std::size_t bytes_recvd,
+                           const ResponseMode& response_mode,
+                           const dns::Rcode& response_rcode) {
+    receive_pending_ = false;
+    // If we encountered an error or received no data then fail.
+    // We expect the client to send good requests.
+    if (error.value() != 0 || bytes_recvd < 1) {
+        ADD_FAILURE() << "FauxServer receive failed: " << error.message();
+        return;
+    }
+
+    // If TSIG key isn't NULL, create a context and use to verify the
+    // request and sign the response.
+    dns::TSIGContextPtr context;
+    if (tsig_key_) {
+        context.reset(new dns::TSIGContext(*tsig_key_));
+    }
+
+    // We have a successfully received data. We need to turn it into
+    // a request in order to build a proper response.
+    // Note D2UpdateMessage is geared towards making requests and
+    // reading responses.  This is the opposite perspective so we have
+    // to a bit of roll-your-own here.
+    dns::Message request(dns::Message::PARSE);
+    util::InputBuffer request_buf(receive_buffer_, bytes_recvd);
+    try {
+        request.fromWire(request_buf);
+
+        // If context is not NULL, then we need to verify the message.
+        if (context) {
+            dns::TSIGError error = context->verify(request.getTSIGRecord(),
+                                                   receive_buffer_,
+                                                   bytes_recvd);
+            if (error != dns::TSIGError::NOERROR()) {
+                isc_throw(TSIGVerifyError, "TSIG verification failed: "
+                          << error.toText());
+            }
+        }
+    } catch (const std::exception& ex) {
+        // If the request cannot be parsed, then fail the test.
+        // We expect the client to send good requests.
+        ADD_FAILURE() << "FauxServer request is corrupt:" << ex.what();
+        return;
+    }
+
+    // The request parsed OK, so let's build a response.
+    // We must use the QID we received in the response or IOFetch will
+    // toss the response out, resulting in eventual timeout.
+    // We fill in the zone with data we know is from the "server".
+    dns::Message response(dns::Message::RENDER);
+    response.setQid(request.getQid());
+    dns::Question question(dns::Name("response.example.com"),
+                           dns::RRClass::ANY(), dns::RRType::SOA());
+    response.addQuestion(question);
+    response.setOpcode(dns::Opcode(dns::Opcode::UPDATE_CODE));
+    response.setHeaderFlag(dns::Message::HEADERFLAG_QR, true);
+
+    // Set the response Rcode to value passed in, default is NOERROR.
+    response.setRcode(response_rcode);
+
+    // Render the response to a buffer.
+    dns::MessageRenderer renderer;
+    util::OutputBuffer response_buf(TEST_MSG_MAX);
+    renderer.setBuffer(&response_buf);
+
+    if (response_mode == INVALID_TSIG) {
+        // Create a different key to sign the response.
+        std::string secret ("key that doesn't match");
+        D2TsigKeyPtr key;
+        ASSERT_NO_THROW(key.reset(new
+                                  D2TsigKey(dns::Name("badkey"),
+                                            dns::TSIGKey::HMACMD5_NAME(),
+                                            secret.c_str(), secret.size())));
+        context.reset(new dns::TSIGContext(*key));
+    }
+
+    response.toWire(renderer, context.get());
+
+    // If mode is to ship garbage, then stomp on part of the rendered
+    // message.
+    if (response_mode == CORRUPT_RESP) {
+        response_buf.writeUint16At(0xFFFF, 2);
+    }
+
+    // Ship the response via synchronous send.
+    try {
+        int cnt = server_socket_->send_to(boost::asio::
+                                          buffer(response_buf.getData(),
+                                                 response_buf.getLength()),
+                                          remote_);
+        // Make sure we sent what we expect to send.
+        if (cnt != response_buf.getLength()) {
+            ADD_FAILURE() << "FauxServer sent: " << cnt << " expected: "
+                          << response_buf.getLength();
+        }
+    } catch (const std::exception& ex) {
+        ADD_FAILURE() << "FauxServer send failed: " << ex.what();
+    }
+
+    if (perpetual_receive_) {
+        // Schedule the next receive
+        receive (response_mode, response_rcode);
+    }
+}
+
+
+
+//********************** TimedIO class ***********************
+
+TimedIO::TimedIO()
+    : io_service_(new isc::asiolink::IOService()),
+     timer_(*io_service_), run_time_(0) {
+}
+
+TimedIO::~TimedIO() {
+}
+
+int
+TimedIO::runTimedIO(int run_time) {
+    run_time_ = run_time;
+    int cnt = io_service_->get_io_service().poll();
+    if (cnt == 0) {
+        timer_.setup(std::bind(&TimedIO::timesUp, this), run_time_);
+        cnt = io_service_->get_io_service().run_one();
+        timer_.cancel();
+    }
+
+    return (cnt);
+}
+
+void
+TimedIO::timesUp() {
+    io_service_->stop();
+    FAIL() << "Test Time: " << run_time_ << " expired";
+}
+
+//********************** TransactionTest class ***********************
+
+const unsigned int TransactionTest::FORWARD_CHG = 0x01;
+const unsigned int TransactionTest::REVERSE_CHG = 0x02;
+const unsigned int TransactionTest::FWD_AND_REV_CHG = REVERSE_CHG | FORWARD_CHG;
+
+TransactionTest::TransactionTest() : ncr_(), cfg_mgr_(new D2CfgMgr()) {
+}
+
+TransactionTest::~TransactionTest() {
+}
+
+void
+TransactionTest::setupForIPv4Transaction(dhcp_ddns::NameChangeType chg_type,
+                                         int change_mask,
+                                         const TSIGKeyInfoPtr& tsig_key_info) {
+    const char* msg_str =
+        "{"
+        " \"change-type\" : 0 , "
+        " \"forward-change\" : true , "
+        " \"reverse-change\" : true , "
+        " \"fqdn\" : \"my.forward.example.com.\" , "
+        " \"ip-address\" : \"192.168.2.1\" , "
+        " \"dhcid\" : \"0102030405060708\" , "
+        " \"lease-expires-on\" : \"20130121132405\" , "
+        " \"lease-length\" : 1300, "
+        " \"use-conflict-resolution\" : true "
+        "}";
+
+    // Create NameChangeRequest from JSON string.
+    ncr_ = dhcp_ddns::NameChangeRequest::fromJSON(msg_str);
+
+    // Set the change type.
+    ncr_->setChangeType(chg_type);
+
+    // If the change mask does not include a forward change clear the
+    // forward domain; otherwise create the domain and its servers.
+    if (!(change_mask & FORWARD_CHG)) {
+        ncr_->setForwardChange(false);
+        forward_domain_.reset();
+    } else {
+        // Create the forward domain and then its servers.
+        forward_domain_ = makeDomain("example.com.", tsig_key_info);
+        addDomainServer(forward_domain_, "forward.example.com",
+                        "127.0.0.1", 5301, tsig_key_info);
+        addDomainServer(forward_domain_, "forward2.example.com",
+                        "127.0.0.1", 5302, tsig_key_info);
+    }
+
+    // If the change mask does not include a reverse change clear the
+    // reverse domain; otherwise create the domain and its servers.
+    if (!(change_mask & REVERSE_CHG)) {
+        ncr_->setReverseChange(false);
+        reverse_domain_.reset();
+    } else {
+        // Create the reverse domain and its server.
+        reverse_domain_ = makeDomain("2.168.192.in.addr.arpa.", tsig_key_info);
+        addDomainServer(reverse_domain_, "reverse.example.com",
+                        "127.0.0.1", 5301, tsig_key_info);
+        addDomainServer(reverse_domain_, "reverse2.example.com",
+                        "127.0.0.1", 5302, tsig_key_info);
+    }
+}
+
+void
+TransactionTest::setupForIPv4Transaction(dhcp_ddns::NameChangeType chg_type,
+                                         int change_mask,
+                                         const std::string& key_name) {
+    setupForIPv4Transaction(chg_type, change_mask, makeTSIGKeyInfo(key_name));
+}
+
+void
+TransactionTest::setupForIPv6Transaction(dhcp_ddns::NameChangeType chg_type,
+                                         int change_mask,
+                                         const TSIGKeyInfoPtr& tsig_key_info) {
+    const char* msg_str =
+        "{"
+        " \"change-type\" : 0 , "
+        " \"forward-change\" : true , "
+        " \"reverse-change\" : true , "
+        " \"fqdn\" : \"my6.forward.example.com.\" , "
+        " \"ip-address\" : \"2001:1::100\" , "
+        " \"dhcid\" : \"0102030405060708\" , "
+        " \"lease-expires-on\" : \"20130121132405\" , "
+        " \"lease-length\" : 1300, "
+        " \"use-conflict-resolution\" : true "
+        "}";
+
+    // Create NameChangeRequest from JSON string.
+    ncr_ = makeNcrFromString(msg_str);
+
+    // Set the change type.
+    ncr_->setChangeType(chg_type);
+
+    // If the change mask does not include a forward change clear the
+    // forward domain; otherwise create the domain and its servers.
+    if (!(change_mask & FORWARD_CHG)) {
+        ncr_->setForwardChange(false);
+        forward_domain_.reset();
+    } else {
+        // Create the forward domain and then its servers.
+        forward_domain_ = makeDomain("example.com.", tsig_key_info);
+        addDomainServer(forward_domain_, "fwd6-server.example.com",
+                        "::1", 5301, tsig_key_info);
+        addDomainServer(forward_domain_, "fwd6-server2.example.com",
+                        "::1", 5302, tsig_key_info);
+    }
+
+    // If the change mask does not include a reverse change clear the
+    // reverse domain; otherwise create the domain and its servers.
+    if (!(change_mask & REVERSE_CHG)) {
+        ncr_->setReverseChange(false);
+        reverse_domain_.reset();
+    } else {
+        // Create the reverse domain and its server.
+        reverse_domain_ = makeDomain("1.2001.ip6.arpa.", tsig_key_info);
+        addDomainServer(reverse_domain_, "rev6-server.example.com",
+                        "::1", 5301, tsig_key_info);
+        addDomainServer(reverse_domain_, "rev6-server2.example.com",
+                        "::1", 5302, tsig_key_info);
+    }
+}
+
+void
+TransactionTest::setupForIPv6Transaction(dhcp_ddns::NameChangeType chg_type,
+                                         int change_mask,
+                                         const std::string& key_name) {
+    setupForIPv6Transaction(chg_type, change_mask, makeTSIGKeyInfo(key_name));
+}
+
+
+//********************** Functions ****************************
+
+void
+checkRRCount(const D2UpdateMessagePtr& request,
+             D2UpdateMessage::UpdateMsgSection section, int count) {
+    dns::RRsetIterator rrset_it = request->beginSection(section);
+    dns::RRsetIterator rrset_end = request->endSection(section);
+
+    ASSERT_EQ(count, std::distance(rrset_it, rrset_end));
+}
+
+void
+checkZone(const D2UpdateMessagePtr& request, const std::string& exp_zone_name) {
+    // Verify the zone section info.
+    D2ZonePtr zone = request->getZone();
+    EXPECT_TRUE(zone);
+    EXPECT_EQ(exp_zone_name, zone->getName().toText());
+    EXPECT_EQ(dns::RRClass::IN().getCode(), zone->getClass().getCode());
+}
+
+void
+checkRR(dns::RRsetPtr rrset, const std::string& exp_name,
+        const dns::RRClass& exp_class, const dns::RRType& exp_type,
+        unsigned int exp_ttl, dhcp_ddns::NameChangeRequestPtr ncr,
+        bool has_rdata) {
+    // Verify the FQDN/DHCID RR fields.
+    EXPECT_EQ(exp_name, rrset->getName().toText());
+    EXPECT_EQ(exp_class.getCode(), rrset->getClass().getCode());
+    EXPECT_EQ(exp_type.getCode(), rrset->getType().getCode());
+    EXPECT_EQ(exp_ttl, rrset->getTTL().getValue());
+    if ((!has_rdata) ||
+       (exp_type == dns::RRType::ANY() || exp_class == dns::RRClass::ANY())) {
+        // ANY types do not have RData
+        ASSERT_EQ(0, rrset->getRdataCount());
+        return;
+    }
+
+    ASSERT_EQ(1, rrset->getRdataCount());
+    dns::RdataIteratorPtr rdata_it = rrset->getRdataIterator();
+    ASSERT_TRUE(rdata_it);
+
+    if ((exp_type == dns::RRType::A()) ||
+        (exp_type == dns::RRType::AAAA())) {
+        // should have lease rdata
+        EXPECT_EQ(ncr->getIpAddress(), rdata_it->getCurrent().toText());
+    } else if (exp_type == dns::RRType::PTR()) {
+        // should have PTR rdata
+        EXPECT_EQ(ncr->getFqdn(), rdata_it->getCurrent().toText());
+    } else if (exp_type == dns::RRType::DHCID()) {
+        // should have DHCID rdata
+        const std::vector<uint8_t>& ncr_dhcid = ncr->getDhcid().getBytes();
+        util::InputBuffer buffer(ncr_dhcid.data(), ncr_dhcid.size());
+        dns::rdata::in::DHCID rdata_ref(buffer, ncr_dhcid.size());
+        EXPECT_EQ(0, rdata_ref.compare(rdata_it->getCurrent()));
+    } else {
+        // we got a problem
+        FAIL();
+    }
+}
+
+dns::RRsetPtr
+getRRFromSection(const D2UpdateMessagePtr& request,
+                 D2UpdateMessage::UpdateMsgSection section, int index) {
+    dns::RRsetIterator rrset_it = request->beginSection(section);
+    dns::RRsetIterator rrset_end = request->endSection(section);
+
+    if (std::distance(rrset_it, rrset_end) <= index) {
+        // Return an empty pointer if index is out of range.
+        return (dns::RRsetPtr());
+    }
+
+    std::advance(rrset_it, index);
+    return (*rrset_it);
+}
+
+dhcp_ddns::NameChangeRequestPtr
+makeNcrFromString(const std::string& ncr_str) {
+    return (dhcp_ddns::NameChangeRequest::fromJSON(ncr_str));
+}
+
+DdnsDomainPtr
+makeDomain(const std::string& zone_name, const std::string& key_name) {
+    DnsServerInfoStoragePtr servers(new DnsServerInfoStorage());
+    DdnsDomainPtr domain(new DdnsDomain(zone_name, servers, key_name));
+    return (domain);
+}
+
+DdnsDomainPtr
+makeDomain(const std::string& zone_name, const TSIGKeyInfoPtr &tsig_key_info) {
+    DdnsDomainPtr domain;
+    DnsServerInfoStoragePtr servers(new DnsServerInfoStorage());
+    std::string key_name;
+    if (tsig_key_info) {
+        key_name = tsig_key_info->getName();
+    }
+    domain.reset(new DdnsDomain(zone_name, servers, key_name));
+    return (domain);
+}
+
+TSIGKeyInfoPtr
+makeTSIGKeyInfo(const std::string& key_name, const std::string& secret,
+                const std::string& algorithm) {
+    TSIGKeyInfoPtr key_info;
+    if (!key_name.empty()) {
+        if (!secret.empty()) {
+            key_info.reset(new TSIGKeyInfo(key_name, algorithm, secret));
+        } else {
+            // Since secret was left blank, we'll convert key_name into a
+            // base64 encoded string and use that.
+            const uint8_t* bytes = reinterpret_cast<const uint8_t*>
+                                                   (key_name.c_str());
+            size_t len = key_name.size();
+            const vector<uint8_t> key_name_v(bytes, bytes + len);
+            std::string key_name64
+                = isc::util::encode::encodeBase64(key_name_v);
+
+            // Now, make the TSIGKeyInfo with a real base64 secret.
+            key_info.reset(new TSIGKeyInfo(key_name, algorithm, key_name64));
+        }
+    }
+
+    return (key_info);
+}
+
+void
+addDomainServer(DdnsDomainPtr& domain, const std::string& name,
+                const std::string& ip, const size_t port,
+                const TSIGKeyInfoPtr &tsig_key_info) {
+    DnsServerInfoPtr server(new DnsServerInfo(name, asiolink::IOAddress(ip),
+                                              port, true, tsig_key_info));
+    domain->getServers()->push_back(server);
+}
+
+// Verifies that the contents of the given transaction's DNS update request
+// is correct for adding a forward DNS entry
+void
+checkAddFwdAddressRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getForwardDomain()->getName();
+    std::string exp_fqdn = ncr->getFqdn();
+    const dns::RRType& exp_ip_rr_type = tran.getAddressRRType();
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify the PREREQUISITE SECTION
+    // Should be 1 which tests for FQDN does not exist.
+    dns::RRsetPtr rrset;
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 1);
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::NONE(), dns::RRType::ANY(), 0, ncr);
+
+    // Verify the UPDATE SECTION
+    // Should be 2 RRs: 1 to add the FQDN/IP and one to add the DHCID RR
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 2);
+
+    // Fetch ttl.
+    uint32_t ttl = ncr->getLeaseLength();
+
+    // First, Verify the FQDN/IP add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), exp_ip_rr_type, ttl, ncr);
+
+    // Now, verify the DHCID add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 1));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), dns::RRType::DHCID(),
+            ttl, ncr);
+
+    // Verify there are no RRs in the ADDITIONAL Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_ADDITIONAL, 0);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+// Verifies that the contents of the given transaction's DNS update request
+// is correct for replacing a forward DNS entry
+void
+checkReplaceFwdAddressRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getForwardDomain()->getName();
+    std::string exp_fqdn = ncr->getFqdn();
+    const dns::RRType& exp_ip_rr_type = tran.getAddressRRType();
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify the PREREQUISITE SECTION
+    // Should be 2,  1 which tests for FQDN does exist and the other
+    // checks for a matching DHCID.
+    dns::RRsetPtr rrset;
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 2);
+
+    // Verify the FQDN test RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), dns::RRType::ANY(), 0, ncr);
+
+    // Verify the DHCID test RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 1));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), dns::RRType::DHCID(), 0, ncr);
+
+    // Verify the UPDATE SECTION
+    // Should be 2,  1 which deletes the existing FQDN/IP and one that
+    // adds the new one.
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 2);
+
+    // Fetch ttl.
+    uint32_t ttl = ncr->getLeaseLength();
+
+    // Verify the FQDN delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), exp_ip_rr_type, 0, ncr);
+
+    // Verify the FQDN/IP add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 1));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), exp_ip_rr_type, ttl, ncr);
+
+    // Verify there are no RRs in the ADDITIONAL Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_ADDITIONAL, 0);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+// Verifies that the contents of the given transaction's DNS update request
+// is correct for replacing a reverse DNS entry
+void
+checkReplaceRevPtrsRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getReverseDomain()->getName();
+    std::string exp_rev_addr = D2CfgMgr::reverseIpAddress(ncr->getIpAddress());
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify there are no RRs in the PREREQUISITE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 0);
+
+    // Fetch ttl.
+    uint32_t ttl = ncr->getLeaseLength();
+
+    // Verify the UPDATE Section.
+    // It should contain 4 RRs:
+    // 1. A delete all PTR RRs for the given IP
+    // 2. A delete of all DHCID RRs for the given IP
+    // 3. An add of the new PTR RR
+    // 4. An add of the new DHCID RR
+    dns::RRsetPtr rrset;
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 4);
+
+    // Verify the PTR delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::ANY(), dns::RRType::PTR(),
+            0, ncr);
+
+    // Verify the DHCID delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 1));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::ANY(), dns::RRType::DHCID(),
+            0, ncr);
+
+    // Verify the PTR add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 2));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::IN(), dns::RRType::PTR(),
+            ttl, ncr);
+
+    // Verify the DHCID add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 3));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::IN(), dns::RRType::DHCID(),
+            ttl, ncr);
+
+    // Verify there are no RRs in the ADDITIONAL Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_ADDITIONAL, 0);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+void
+checkRemoveFwdAddressRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getForwardDomain()->getName();
+    std::string exp_fqdn = ncr->getFqdn();
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify there is 1 RR in the PREREQUISITE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 1);
+
+    // Verify the DHCID matching assertion RR.
+    dns::RRsetPtr rrset;
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), dns::RRType::DHCID(),
+            0, ncr);
+
+    // Verify there is 1 RR in the UPDATE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 1);
+
+    // Verify the FQDN/IP delete RR.
+    const dns::RRType& exp_ip_rr_type = tran.getAddressRRType();
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::NONE(), exp_ip_rr_type,
+            0, ncr);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+void
+checkRemoveFwdRRsRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getForwardDomain()->getName();
+    std::string exp_fqdn = ncr->getFqdn();
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify there is 1 RR in the PREREQUISITE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 3);
+
+    // Verify the DHCID matches assertion.
+    dns::RRsetPtr rrset;
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), dns::RRType::DHCID(),
+            0, ncr);
+
+    // Verify the NO A RRs assertion.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 1));
+    checkRR(rrset, exp_fqdn, dns::RRClass::NONE(), dns::RRType::A(),
+            0, ncr, NO_RDATA);
+
+    // Verify the NO AAAA RRs assertion.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 2));
+    checkRR(rrset, exp_fqdn, dns::RRClass::NONE(), dns::RRType::AAAA(),
+            0, ncr, NO_RDATA);
+
+    // Verify there is 1 RR in the UPDATE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 1);
+
+    // Verify the delete all for the FQDN RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), dns::RRType::ANY(),
+            0, ncr);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+void
+checkRemoveRevPtrsRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getReverseDomain()->getName();
+    std::string exp_rev_addr = D2CfgMgr::reverseIpAddress(ncr->getIpAddress());
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify there is 1 RR in the PREREQUISITE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 1);
+
+    // Verify the FQDN-PTRNAME assertion RR.
+    dns::RRsetPtr rrset;
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_PREREQUISITE, 0));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::IN(), dns::RRType::PTR(),
+            0, ncr);
+
+    // Verify there is 1 RR in the UPDATE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 1);
+
+    // Verify the delete all for the FQDN RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::ANY(), dns::RRType::ANY(),
+            0, ncr);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+std::string
+toHexText(const uint8_t* data, size_t len) {
+    std::ostringstream stream;
+    stream << "Data length is: " << len << std::endl;
+    for (int i = 0; i < len; ++i) {
+        if (i > 0 && ((i % 16) == 0)) {
+            stream << std::endl;
+        }
+
+        stream << setfill('0') << setw(2) << setbase(16)
+               << static_cast<unsigned int>(data[i]) << " ";
+    }
+
+    return (stream.str());
+}
+
+// Verifies that the contents of the given transaction's DNS update request
+// is correct for replacing a forward DNS entry when not using conflict
+// resolution.
+void
+checkSimpleReplaceFwdAddressRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getForwardDomain()->getName();
+    std::string exp_fqdn = ncr->getFqdn();
+    const dns::RRType& exp_ip_rr_type = tran.getAddressRRType();
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify the PREREQUISITE SECTION
+    // There should be no prerequisites.
+    dns::RRsetPtr rrset;
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 0);
+
+    // Verify the UPDATE SECTION
+    // Should be 4
+    // 1. delete of the FQDN/IP RR
+    // 2. delete of the DHCID RR
+    // 3. add of the FQDN/IP RR
+    // 4. add of the DHCID RR
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 4);
+
+    // Fetch ttl.
+    uint32_t ttl = ncr->getLeaseLength();
+
+    // Verify the FQDN delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), exp_ip_rr_type, 0, ncr);
+
+    // Verify the DHCID delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 1));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), dns::RRType::DHCID(),
+            0, ncr);
+
+    // Verify the FQDN/IP add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 2));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), exp_ip_rr_type, ttl, ncr);
+
+    // Now, verify the DHCID add RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 3));
+    checkRR(rrset, exp_fqdn, dns::RRClass::IN(), dns::RRType::DHCID(),
+            ttl, ncr);
+
+    // Verify there are no RRs in the ADDITIONAL Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_ADDITIONAL, 0);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+void
+checkSimpleRemoveFwdRRsRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getForwardDomain()->getName();
+    std::string exp_fqdn = ncr->getFqdn();
+    const dns::RRType& exp_ip_rr_type = tran.getAddressRRType();
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify there no prerequisites.
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 0);
+
+    // Verify there are 2 RRs in the UPDATE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 2);
+
+    // Verify the FQDN delete RR.
+    dns::RRsetPtr rrset;
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), exp_ip_rr_type, 0, ncr);
+
+    // Verify the DHCID delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 1));
+    checkRR(rrset, exp_fqdn, dns::RRClass::ANY(), dns::RRType::DHCID(),
+            0, ncr);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+// Verifies that the contents of the given transaction's DNS update request
+// is correct for removing a reverse DNS entry when not using conflict
+// resolution.
+void
+checkSimpleRemoveRevPtrsRequest(NameChangeTransaction& tran) {
+    const D2UpdateMessagePtr& request = tran.getDnsUpdateRequest();
+    ASSERT_TRUE(request);
+
+    // Safety check.
+    dhcp_ddns::NameChangeRequestPtr ncr = tran.getNcr();
+    ASSERT_TRUE(ncr);
+
+    std::string exp_zone_name = tran.getReverseDomain()->getName();
+    std::string exp_rev_addr = D2CfgMgr::reverseIpAddress(ncr->getIpAddress());
+
+    // Verify the zone section.
+    checkZone(request, exp_zone_name);
+
+    // Verify there are no RRs in the PREREQUISITE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_PREREQUISITE, 0);
+
+    // Verify there is 2 RRs in the UPDATE Section.
+    checkRRCount(request, D2UpdateMessage::SECTION_UPDATE, 2);
+
+    // Verify the FQDN delete RR.
+    dns::RRsetPtr rrset;
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 0));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::ANY(), dns::RRType::PTR(), 0, ncr);
+
+    // Verify the DHCID delete RR.
+    ASSERT_TRUE(rrset = getRRFromSection(request, D2UpdateMessage::
+                                                  SECTION_UPDATE, 1));
+    checkRR(rrset, exp_rev_addr, dns::RRClass::ANY(), dns::RRType::DHCID(), 0, ncr);
+
+    // Verify that it will render toWire without throwing.
+    dns::MessageRenderer renderer;
+    ASSERT_NO_THROW(request->toWire(renderer));
+}
+
+// Verifies the current state and next event in a transaction
+void
+checkContext(NameChangeTransactionPtr trans, const int exp_state,
+             const int exp_evt, const std::string& file, int line) {
+    ASSERT_TRUE(trans);
+    ASSERT_TRUE(exp_state == trans->getCurrState() && exp_evt == trans->getNextEvent())
+            << "expected state: " << trans->getStateLabel(exp_state)
+            << " event: " << trans->getEventLabel(exp_evt)
+            << ", actual context: " << trans->getContextStr()
+            << " at " << file << ":" << line;
+}
+
+} // namespace isc::d2
+} // namespace isc