dhcp4_test_utils.h 23.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129
// Copyright (C) 2013  Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.

#include <config.h>
#include <sstream>

#include <asiolink/io_address.h>
#include <dhcp/dhcp4.h>
#include <dhcp/iface_mgr.h>
#include <dhcp/option.h>
#include <dhcp/option4_addrlst.h>
#include <dhcp/option_custom.h>
#include <dhcp/option_int_array.h>
#include <dhcp/pkt_filter.h>
#include <dhcp/pkt_filter_inet.h>
#include <dhcp4/config_parser.h>
#include <dhcp4/dhcp4_srv.h>
#include <dhcpsrv/cfgmgr.h>
#include <dhcpsrv/lease_mgr.h>
#include <dhcpsrv/lease_mgr_factory.h>
#include <gtest/gtest.h>

#include <boost/scoped_ptr.hpp>

#include <fstream>
#include <iostream>

#include <arpa/inet.h>

namespace isc {
namespace test {

using namespace isc;
using namespace isc::dhcp;

class NakedDhcpv4Srv: public Dhcpv4Srv {
    // "Naked" DHCPv4 server, exposes internal fields
public:

    /// @brief Constructor.
    ///
    /// This constructor disables default modes of operation used by the
    /// Dhcpv4Srv class:
    /// - Send/receive broadcast messages through sockets on interfaces
    /// which support broadcast traffic.
    /// - Direct DHCPv4 traffic - communication with clients which do not
    /// have IP address assigned yet.
    ///
    /// Enabling these modes requires root privilges so they must be
    /// disabled for unit testing.
    ///
    /// Note, that disabling broadcast options on sockets does not impact
    /// the operation of these tests because they use local loopback
    /// interface which doesn't have broadcast capability anyway. It rather
    /// prevents setting broadcast options on other (broadcast capable)
    /// sockets which are opened on other interfaces in Dhcpv4Srv constructor.
    ///
    /// The Direct DHCPv4 Traffic capability can be disabled here because
    /// it is tested with PktFilterLPFTest unittest. The tests which belong
    /// to PktFilterLPFTest can be enabled on demand when root privileges can
    /// be guaranteed.
    ///
    /// @param port port number to listen on; the default value 0 indicates
    /// that sockets should not be opened.
    NakedDhcpv4Srv(uint16_t port = 0)
        : Dhcpv4Srv(port, "type=memfile", false, false) {
    }

    /// @brief fakes packet reception
    /// @param timeout ignored
    ///
    /// The method receives all packets queued in receive queue, one after
    /// another. Once the queue is empty, it initiates the shutdown procedure.
    ///
    /// See fake_received_ field for description
    virtual Pkt4Ptr receivePacket(int /*timeout*/) {

        // If there is anything prepared as fake incoming traffic, use it
        if (!fake_received_.empty()) {
            Pkt4Ptr pkt = fake_received_.front();
            fake_received_.pop_front();
            return (pkt);
        }

        // If not, just trigger shutdown and return immediately
        shutdown();
        return (Pkt4Ptr());
    }

    /// @brief fake packet sending
    ///
    /// Pretend to send a packet, but instead just store it in fake_send_ list
    /// where test can later inspect server's response.
    virtual void sendPacket(const Pkt4Ptr& pkt) {
        fake_sent_.push_back(pkt);
    }

    /// @brief adds a packet to fake receive queue
    ///
    /// See fake_received_ field for description
    void fakeReceive(const Pkt4Ptr& pkt) {
        fake_received_.push_back(pkt);
    }

    virtual ~NakedDhcpv4Srv() {
    }

    /// @brief packets we pretend to receive
    ///
    /// Instead of setting up sockets on interfaces that change between OSes, it
    /// is much easier to fake packet reception. This is a list of packets that
    /// we pretend to have received. You can schedule new packets to be received
    /// using fakeReceive() and NakedDhcpv4Srv::receivePacket() methods.
    std::list<Pkt4Ptr> fake_received_;

    std::list<Pkt4Ptr> fake_sent_;

    using Dhcpv4Srv::adjustRemoteAddr;
130 131
    using Dhcpv4Srv::computeDhcid;
    using Dhcpv4Srv::createNameChangeRequests;
132 133 134 135 136
    using Dhcpv4Srv::processDiscover;
    using Dhcpv4Srv::processRequest;
    using Dhcpv4Srv::processRelease;
    using Dhcpv4Srv::processDecline;
    using Dhcpv4Srv::processInform;
137
    using Dhcpv4Srv::processClientName;
138 139 140 141 142 143
    using Dhcpv4Srv::getServerID;
    using Dhcpv4Srv::loadServerID;
    using Dhcpv4Srv::generateServerID;
    using Dhcpv4Srv::writeServerID;
    using Dhcpv4Srv::sanityCheck;
    using Dhcpv4Srv::srvidToString;
144
    using Dhcpv4Srv::name_change_reqs_;
145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644
};

/// @brief Dummy Packet Filtering class.
///
/// This class reports capability to respond directly to the client which
/// doesn't have address configured yet.
///
/// All packet and socket handling functions do nothing because they are not
/// used in unit tests.
class PktFilterTest : public PktFilter {
public:

    /// @brief Reports 'direct response' capability.
    ///
    /// @return always true.
    virtual bool isDirectResponseSupported() const {
        return (true);
    }

    /// Does nothing.
    virtual int openSocket(const Iface&, const isc::asiolink::IOAddress&,
                           const uint16_t, const bool, const bool) {
        return (0);
    }

    /// Does nothing.
    virtual Pkt4Ptr receive(const Iface&, const SocketInfo&) {
        return Pkt4Ptr();
    }

    /// Does nothing.
    virtual int send(const Iface&, uint16_t, const Pkt4Ptr&) {
        return (0);
    }

};

static const char* SRVID_FILE = "server-id-test.txt";

class Dhcpv4SrvTest : public ::testing::Test {
public:

    /// @brief Constructor
    ///
    /// Initializes common objects used in many tests.
    /// Also sets up initial configuration in CfgMgr.
    Dhcpv4SrvTest() :
        rcode_(-1)
    {
        subnet_ = Subnet4Ptr(new Subnet4(isc::asiolink::IOAddress("192.0.2.0"),
                                         24, 1000, 2000, 3000));
        pool_ = Pool4Ptr(new Pool4(isc::asiolink::IOAddress("192.0.2.100"),
                                   isc::asiolink::IOAddress("192.0.2.110")));
        subnet_->addPool(pool_);

        CfgMgr::instance().deleteSubnets4();
        CfgMgr::instance().addSubnet4(subnet_);

        // Add Router option.
        Option4AddrLstPtr opt_routers(new Option4AddrLst(DHO_ROUTERS));
        opt_routers->setAddress(isc::asiolink::IOAddress("192.0.2.2"));
        subnet_->addOption(opt_routers, false, "dhcp4");

        // it's ok if that fails. There should not be such a file anyway
        unlink(SRVID_FILE);

        const IfaceMgr::IfaceCollection& ifaces = IfaceMgr::instance().getIfaces();

        // There must be some interface detected
        if (ifaces.empty()) {
            // We can't use ASSERT in constructor
            ADD_FAILURE() << "No interfaces detected.";
        }

        valid_iface_ = ifaces.begin()->getName();
    }

    virtual ~Dhcpv4SrvTest() {
    }

    /// @brief Add 'Parameter Request List' option to the packet.
    ///
    /// This function PRL option comprising the following option codes:
    /// - 5 - Name Server
    /// - 15 - Domain Name
    /// - 7 - Log Server
    /// - 8 - Quotes Server
    /// - 9 - LPR Server
    ///
    /// @param pkt packet to add PRL option to.
    void addPrlOption(Pkt4Ptr& pkt) {

        OptionUint8ArrayPtr option_prl =
            OptionUint8ArrayPtr(new OptionUint8Array(Option::V4,
                                                     DHO_DHCP_PARAMETER_REQUEST_LIST));

        // Let's request options that have been configured for the subnet.
        option_prl->addValue(DHO_DOMAIN_NAME_SERVERS);
        option_prl->addValue(DHO_DOMAIN_NAME);
        option_prl->addValue(DHO_LOG_SERVERS);
        option_prl->addValue(DHO_COOKIE_SERVERS);
        // Let's also request the option that hasn't been configured. In such
        // case server should ignore request for this particular option.
        option_prl->addValue(DHO_LPR_SERVERS);
        // And add 'Parameter Request List' option into the DISCOVER packet.
        pkt->addOption(option_prl);
    }

    /// @brief Configures options being requested in the PRL option.
    ///
    /// The lpr-servers option is NOT configured here although it is
    /// added to the 'Parameter Request List' option in the
    /// \ref addPrlOption. When requested option is not configured
    /// the server should not return it in its response. The goal
    /// of not configuring the requested option is to verify that
    /// the server will not return it.
    void configureRequestedOptions() {
        // dns-servers
        Option4AddrLstPtr
            option_dns_servers(new Option4AddrLst(DHO_DOMAIN_NAME_SERVERS));
        option_dns_servers->addAddress(isc::asiolink::IOAddress("192.0.2.1"));
        option_dns_servers->addAddress(isc::asiolink::IOAddress("192.0.2.100"));
        ASSERT_NO_THROW(subnet_->addOption(option_dns_servers, false, "dhcp4"));

        // domain-name
        OptionDefinition def("domain-name", DHO_DOMAIN_NAME, OPT_FQDN_TYPE);
        OptionCustomPtr option_domain_name(new OptionCustom(def, Option::V4));
        option_domain_name->writeFqdn("example.com");
        subnet_->addOption(option_domain_name, false, "dhcp4");

        // log-servers
        Option4AddrLstPtr option_log_servers(new Option4AddrLst(DHO_LOG_SERVERS));
        option_log_servers->addAddress(isc::asiolink::IOAddress("192.0.2.2"));
        option_log_servers->addAddress(isc::asiolink::IOAddress("192.0.2.10"));
        ASSERT_NO_THROW(subnet_->addOption(option_log_servers, false, "dhcp4"));

        // cookie-servers
        Option4AddrLstPtr option_cookie_servers(new Option4AddrLst(DHO_COOKIE_SERVERS));
        option_cookie_servers->addAddress(isc::asiolink::IOAddress("192.0.2.1"));
        ASSERT_NO_THROW(subnet_->addOption(option_cookie_servers, false,
                                           "dhcp4"));
    }

    /// @brief checks that the response matches request
    /// @param q query (client's message)
    /// @param a answer (server's message)
    void messageCheck(const Pkt4Ptr& q, const Pkt4Ptr& a) {
        ASSERT_TRUE(q);
        ASSERT_TRUE(a);

        EXPECT_EQ(q->getHops(),   a->getHops());
        EXPECT_EQ(q->getIface(),  a->getIface());
        EXPECT_EQ(q->getIndex(),  a->getIndex());
        EXPECT_EQ(q->getGiaddr(), a->getGiaddr());
        // When processing an incoming packet the remote address
        // is copied as a src address, and the source address is
        // copied as a remote address to the response.
        EXPECT_TRUE(q->getLocalHWAddr() == a->getLocalHWAddr());
        EXPECT_TRUE(q->getRemoteHWAddr() == a->getRemoteHWAddr());

        // Check that bare minimum of required options are there.
        // We don't check options requested by a client. Those
        // are checked elsewhere.
        EXPECT_TRUE(a->getOption(DHO_SUBNET_MASK));
        EXPECT_TRUE(a->getOption(DHO_ROUTERS));
        EXPECT_TRUE(a->getOption(DHO_DHCP_SERVER_IDENTIFIER));
        EXPECT_TRUE(a->getOption(DHO_DHCP_LEASE_TIME));
        EXPECT_TRUE(a->getOption(DHO_SUBNET_MASK));
        EXPECT_TRUE(a->getOption(DHO_DOMAIN_NAME));
        EXPECT_TRUE(a->getOption(DHO_DOMAIN_NAME_SERVERS));

        // Check that something is offered
        EXPECT_TRUE(a->getYiaddr().toText() != "0.0.0.0");
    }

    /// @brief Check that requested options are present.
    ///
    /// @param pkt packet to be checked.
    void optionsCheck(const Pkt4Ptr& pkt) {
        // Check that the requested and configured options are returned
        // in the ACK message.
        EXPECT_TRUE(pkt->getOption(DHO_DOMAIN_NAME))
            << "domain-name not present in the response";
        EXPECT_TRUE(pkt->getOption(DHO_DOMAIN_NAME_SERVERS))
            << "dns-servers not present in the response";
        EXPECT_TRUE(pkt->getOption(DHO_LOG_SERVERS))
            << "log-servers not present in the response";
        EXPECT_TRUE(pkt->getOption(DHO_COOKIE_SERVERS))
            << "cookie-servers not present in the response";
        // Check that the requested but not configured options are not
        // returned in the ACK message.
        EXPECT_FALSE(pkt->getOption(DHO_LPR_SERVERS))
            << "domain-name present in the response but it is"
            << " expected not to be present";
    }

    /// @brief generates client-id option
    ///
    /// Generate client-id option of specified length
    /// Ids with different lengths are sufficent to generate
    /// unique ids. If more fine grained control is required,
    /// tests generate client-ids on their own.
    /// Sets client_id_ field.
    /// @param size size of the client-id to be generated
    OptionPtr generateClientId(size_t size = 4) {

        OptionBuffer clnt_id(size);
        for (int i = 0; i < size; i++) {
            clnt_id[i] = 100 + i;
        }

        client_id_ = ClientIdPtr(new ClientId(clnt_id));

        return (OptionPtr(new Option(Option::V4, DHO_DHCP_CLIENT_IDENTIFIER,
                                     clnt_id.begin(),
                                     clnt_id.begin() + size)));
    }

    /// @brief generate hardware address
    ///
    /// @param size size of the generated MAC address
    /// @param pointer to Hardware Address object
    HWAddrPtr generateHWAddr(size_t size = 6) {
        const uint8_t hw_type = 123; // Just a fake number (typically 6=HTYPE_ETHER, see dhcp4.h)
        OptionBuffer mac(size);
        for (int i = 0; i < size; ++i) {
            mac[i] = 50 + i;
        }
        return (HWAddrPtr(new HWAddr(mac, hw_type)));
    }

    /// Check that address was returned from proper range, that its lease
    /// lifetime is correct, that T1 and T2 are returned properly
    /// @param rsp response to be checked
    /// @param subnet subnet that should be used to verify assigned address
    ///        and options
    /// @param t1_mandatory is T1 mandatory?
    /// @param t2_mandatory is T2 mandatory?
    void checkAddressParams(const Pkt4Ptr& rsp, const SubnetPtr subnet,
                            bool t1_mandatory = false,
                            bool t2_mandatory = false) {

        // Technically inPool implies inRange, but let's be on the safe
        // side and check both.
        EXPECT_TRUE(subnet->inRange(rsp->getYiaddr()));
        EXPECT_TRUE(subnet->inPool(rsp->getYiaddr()));

        // Check lease time
        OptionPtr opt = rsp->getOption(DHO_DHCP_LEASE_TIME);
        if (!opt) {
            ADD_FAILURE() << "Lease time option missing in response";
        } else {
            EXPECT_EQ(opt->getUint32(), subnet->getValid());
        }

        // Check T1 timer
        opt = rsp->getOption(DHO_DHCP_RENEWAL_TIME);
        if (opt) {
            EXPECT_EQ(opt->getUint32(), subnet->getT1());
        } else {
            if (t1_mandatory) {
                ADD_FAILURE() << "Required T1 option missing";
            }
        }

        // Check T2 timer
        opt = rsp->getOption(DHO_DHCP_REBINDING_TIME);
        if (opt) {
            EXPECT_EQ(opt->getUint32(), subnet->getT2());
        } else {
            if (t2_mandatory) {
                ADD_FAILURE() << "Required T2 option missing";
            }
        }
    }

    /// @brief Basic checks for generated response (message type and trans-id).
    ///
    /// @param rsp response packet to be validated
    /// @param expected_message_type expected message type
    /// @param expected_transid expected transaction-id
    void checkResponse(const Pkt4Ptr& rsp, uint8_t expected_message_type,
                       uint32_t expected_transid) {
        ASSERT_TRUE(rsp);
        EXPECT_EQ(expected_message_type, rsp->getType());
        EXPECT_EQ(expected_transid, rsp->getTransid());
    }

    /// @brief Checks if the lease sent to client is present in the database
    ///
    /// @param rsp response packet to be validated
    /// @param client_id expected client-identifier (or NULL)
    /// @param HWAddr expected hardware address (not used now)
    /// @param expected_addr expected address
    Lease4Ptr checkLease(const Pkt4Ptr& rsp, const OptionPtr& client_id,
                         const HWAddrPtr&,
                         const isc::asiolink::IOAddress& expected_addr) {

        ClientIdPtr id;
        if (client_id) {
            OptionBuffer data = client_id->getData();
            id.reset(new ClientId(data));
        }

        Lease4Ptr lease = LeaseMgrFactory::instance().getLease4(expected_addr);
        if (!lease) {
            std::cout << "Lease for " << expected_addr.toText()
                      << " not found in the database backend.";
            return (Lease4Ptr());
        }

        EXPECT_EQ(rsp->getYiaddr().toText(), expected_addr.toText());

        EXPECT_EQ(expected_addr.toText(), lease->addr_.toText());
        if (client_id) {
            EXPECT_TRUE(*lease->client_id_ == *id);
        }
        EXPECT_EQ(subnet_->getID(), lease->subnet_id_);

        return (lease);
    }

    /// @brief Checks if server response (OFFER, ACK, NAK) includes proper server-id
    /// @param rsp response packet to be validated
    /// @param expected_srvid expected value of server-id
    void checkServerId(const Pkt4Ptr& rsp, const OptionPtr& expected_srvid) {
        // Check that server included its server-id
        OptionPtr opt = rsp->getOption(DHO_DHCP_SERVER_IDENTIFIER);
        ASSERT_TRUE(opt);
        EXPECT_EQ(opt->getType(), expected_srvid->getType() );
        EXPECT_EQ(opt->len(), expected_srvid->len() );
        EXPECT_TRUE(opt->getData() == expected_srvid->getData());
    }

    /// @brief Checks if server response (OFFER, ACK, NAK) includes proper client-id
    /// @param rsp response packet to be validated
    /// @param expected_clientid expected value of client-id
    void checkClientId(const Pkt4Ptr& rsp, const OptionPtr& expected_clientid) {
        // check that server included our own client-id
        OptionPtr opt = rsp->getOption(DHO_DHCP_CLIENT_IDENTIFIER);
        ASSERT_TRUE(opt);
        EXPECT_EQ(expected_clientid->getType(), opt->getType());
        EXPECT_EQ(expected_clientid->len(), opt->len());
        EXPECT_TRUE(expected_clientid->getData() == opt->getData());
    }

    /// @brief Tests if Discover or Request message is processed correctly
    ///
    /// @param msg_type DHCPDISCOVER or DHCPREQUEST
    void testDiscoverRequest(const uint8_t msg_type) {
        // Create an instance of the tested class.
        boost::scoped_ptr<NakedDhcpv4Srv> srv(new NakedDhcpv4Srv(0));

        // Initialize the source HW address.
        std::vector<uint8_t> mac(6);
        for (int i = 0; i < 6; ++i) {
            mac[i] = i * 10;
        }
        // Initialized the destination HW address.
        std::vector<uint8_t> dst_mac(6);
        for (int i = 0; i < 6; ++i) {
            dst_mac[i] = i * 20;
        }
        // Create a DHCP message. It will be used to simulate the
        // incoming message.
        boost::shared_ptr<Pkt4> req(new Pkt4(msg_type, 1234));
        // Create a response message. It will hold a reponse packet.
        // Initially, set it to NULL.
        boost::shared_ptr<Pkt4> rsp;
        // Set the name of the interface on which packet is received.
        req->setIface("eth0");
        // Set the interface index. It is just a dummy value and will
        // not be interpreted.
        req->setIndex(17);
        // Set the target HW address. This value is normally used to
        // construct the data link layer header.
        req->setRemoteHWAddr(1, 6, dst_mac);
        // Set the HW address. This value is set on DHCP level (in chaddr).
        req->setHWAddr(1, 6, mac);
        // Set local HW address. It is used to construct the data link layer
        // header.
        req->setLocalHWAddr(1, 6, mac);
        // Set target IP address.
        req->setRemoteAddr(isc::asiolink::IOAddress("192.0.2.55"));
        // Set relay address.
        req->setGiaddr(isc::asiolink::IOAddress("192.0.2.10"));

        // We are going to test that certain options are returned
        // in the response message when requested using 'Parameter
        // Request List' option. Let's configure those options that
        // are returned when requested.
        configureRequestedOptions();

        if (msg_type == DHCPDISCOVER) {
            ASSERT_NO_THROW(
                rsp = srv->processDiscover(req);
            );

            // Should return OFFER
            ASSERT_TRUE(rsp);
            EXPECT_EQ(DHCPOFFER, rsp->getType());

        } else {
            ASSERT_NO_THROW(
                rsp = srv->processRequest(req);
            );

            // Should return ACK
            ASSERT_TRUE(rsp);
            EXPECT_EQ(DHCPACK, rsp->getType());

        }

        messageCheck(req, rsp);

        // We did not request any options so these should not be present
        // in the RSP.
        EXPECT_FALSE(rsp->getOption(DHO_LOG_SERVERS));
        EXPECT_FALSE(rsp->getOption(DHO_COOKIE_SERVERS));
        EXPECT_FALSE(rsp->getOption(DHO_LPR_SERVERS));

        // Repeat the test but request some options.
        // Add 'Parameter Request List' option.
        addPrlOption(req);

        if (msg_type == DHCPDISCOVER) {
            ASSERT_NO_THROW(
                rsp = srv->processDiscover(req);
            );

            // Should return non-NULL packet.
            ASSERT_TRUE(rsp);
            EXPECT_EQ(DHCPOFFER, rsp->getType());

        } else {
            ASSERT_NO_THROW(
                rsp = srv->processRequest(req);
            );

            // Should return non-NULL packet.
            ASSERT_TRUE(rsp);
            EXPECT_EQ(DHCPACK, rsp->getType());

        }

        // Check that the requested options are returned.
        optionsCheck(rsp);

    }

    /// @brief This function cleans up after the test.
    virtual void TearDown() {

        CfgMgr::instance().deleteSubnets4();

        // Let's clean up if there is such a file.
        unlink(SRVID_FILE);

        // Close all open sockets.
        IfaceMgr::instance().closeSockets();

        // Some unit tests override the default packet filtering class, used
        // by the IfaceMgr. The dummy class, called PktFilterTest, reports the
        // capability to directly respond to the clients without IP address
        // assigned. This capability is not supported by the default packet
        // filtering class: PktFilterInet. Therefore setting the dummy class
        // allows to test scenarios, when server responds to the broadcast address
        // on client's request, despite having support for direct response.
        // The following call restores the use of original packet filtering class
        // after the test.
        try {
            IfaceMgr::instance().setPacketFilter(PktFilterPtr(new PktFilterInet()));

        } catch (const Exception& ex) {
            FAIL() << "Failed to restore the default (PktFilterInet) packet filtering"
                   << " class after the test. Exception has been caught: "
                   << ex.what();
        }
    }

    /// @brief A subnet used in most tests
    Subnet4Ptr subnet_;

    /// @brief A pool used in most tests
    Pool4Ptr pool_;

    /// @brief A client-id used in most tests
    ClientIdPtr client_id_;

    int rcode_;

    isc::data::ConstElementPtr comment_;

    // Name of a valid network interface
    std::string valid_iface_;
};


} // end of test namespace
} // end of isc namespace