kea/src/lib/dhcp/tests/pkt4_unittest.cc

// Copyright (C) 2011-2014  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 <asiolink/io_address.h>
#include <dhcp/dhcp4.h>
#include <dhcp/libdhcp++.h>
#include <dhcp/docsis3_option_defs.h>
#include <dhcp/option_string.h>
#include <dhcp/pkt4.h>
#include <exceptions/exceptions.h>
#include <util/buffer.h>

#include <boost/shared_array.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/static_assert.hpp>
#include <gtest/gtest.h>

#include <iostream>
#include <sstream>

#include <arpa/inet.h>

using namespace std;
using namespace isc;
using namespace isc::asiolink;
using namespace isc::dhcp;
using namespace isc::util;
// Don't import the entire boost namespace.  It will unexpectedly hide uint8_t
// for some systems.
using boost::scoped_ptr;

namespace {

/// @brief A class which contains a custom callback function to unpack options.
///
/// This is a class used by the tests which verify that the custom callback
/// functions can be installed to unpack options from a message. When the
/// callback function is called, the executed_ member is set to true to allow
/// verification that the callback was really called. Internally, this class
/// uses libdhcp++ to unpack options so the options parsing algorithm remains
/// unchanged after installation of the callback.
class CustomUnpackCallback {
public:

    /// @brief Constructor
    ///
    /// Marks that callback hasn't been called.
    CustomUnpackCallback()
        : executed_(false) {
    }

    /// @brief A callback
    ///
    /// Contains custom implementation of the callback.
    ///
    /// @param buf a A buffer holding options in on-wire format.
    /// @param option_space A name of the option space being encapsulated by
    /// the option being parsed.
    /// @param [out] options A reference to the collection where parsed options
    /// will be stored.
    /// @return An offset to the first byte after last parsed option.
    size_t execute(const OptionBuffer& buf,
                   const std::string& option_space,
                   isc::dhcp::OptionCollection& options) {
        // Set the executed_ member to true to allow verification that the
        // callback has been actually called.
        executed_ = true;
        // Use default implementation of the unpack algorithm to parse options.
        return (LibDHCP::unpackOptions4(buf, option_space, options));
    }

    /// A flag which indicates if callback function has been called.
    bool executed_;
};

/// V4 Options being used for pack/unpack testing.
/// For test simplicity, all selected options have
/// variable length data so as there are no restrictions
/// on a length of their data.
static uint8_t v4_opts[] = {
    12,  3, 0,   1,  2, // Hostname
    14,  3, 10, 11, 12, // Merit Dump File
    53, 1, 2, // Message Type (required to not throw exception during unpack)
    60,  3, 20, 21, 22, // Class Id
    128, 3, 30, 31, 32, // Vendor specific
    254, 3, 40, 41, 42, // Reserved
};

// Sample data
const uint8_t dummyOp = BOOTREQUEST;
const uint8_t dummyHtype = 6;
const uint8_t dummyHlen = 6;
const uint8_t dummyHops = 13;
const uint32_t dummyTransid = 0x12345678;
const uint16_t dummySecs = 42;
const uint16_t dummyFlags = BOOTP_BROADCAST;

const IOAddress dummyCiaddr("192.0.2.1");
const IOAddress dummyYiaddr("1.2.3.4");
const IOAddress dummySiaddr("192.0.2.255");
const IOAddress dummyGiaddr("255.255.255.255");

// a dummy MAC address
const uint8_t dummyMacAddr[] = {0, 1, 2, 3, 4, 5};

// A dummy MAC address, padded with 0s
const uint8_t dummyChaddr[16] = {0, 1, 2, 3, 4, 5, 0, 0,
                                 0, 0, 0, 0, 0, 0, 0, 0 };

// Let's use some creative test content here (128 chars + \0)
const uint8_t dummyFile[] = "Lorem ipsum dolor sit amet, consectetur "
    "adipiscing elit. Proin mollis placerat metus, at "
    "lacinia orci ornare vitae. Mauris amet.";

// Yet another type of test content (64 chars + \0)
const uint8_t dummySname[] = "Lorem ipsum dolor sit amet, consectetur "
    "adipiscing elit posuere.";

BOOST_STATIC_ASSERT(sizeof(dummyFile)  == Pkt4::MAX_FILE_LEN + 1);
BOOST_STATIC_ASSERT(sizeof(dummySname) == Pkt4::MAX_SNAME_LEN + 1);


class Pkt4Test : public ::testing::Test {
public:
    Pkt4Test() {
    }

    /// @brief Generates test packet.
    ///
    /// Allocates and generates test packet, with all fixed fields set to non-zero
    /// values. Content is not always reasonable.
    ///
    /// See generateTestPacket2() function that returns exactly the same packet in
    /// on-wire format.
    ///
    /// @return pointer to allocated Pkt4 object.
    Pkt4Ptr generateTestPacket1() {

        boost::shared_ptr<Pkt4> pkt(new Pkt4(DHCPDISCOVER, dummyTransid));

        vector<uint8_t> vectorMacAddr(dummyMacAddr, dummyMacAddr
                                      + sizeof(dummyMacAddr));

        // hwType = 6(ETHERNET), hlen = 6(MAC address len)
        pkt->setHWAddr(dummyHtype, dummyHlen, vectorMacAddr);
        pkt->setHops(dummyHops); // 13 relays. Wow!
        // Transaction-id is already set.
        pkt->setSecs(dummySecs);
        pkt->setFlags(dummyFlags); // all flags set
        pkt->setCiaddr(dummyCiaddr);
        pkt->setYiaddr(dummyYiaddr);
        pkt->setSiaddr(dummySiaddr);
        pkt->setGiaddr(dummyGiaddr);
        // Chaddr already set with setHWAddr().
        pkt->setSname(dummySname, 64);
        pkt->setFile(dummyFile, 128);

        return (pkt);
    }

    /// @brief Generates test packet.
    ///
    /// Allocates and generates on-wire buffer that represents test packet, with all
    /// fixed fields set to non-zero values.  Content is not always reasonable.
    ///
    /// See generateTestPacket1() function that returns exactly the same packet as
    /// Pkt4 object.
    ///
    /// @return pointer to allocated Pkt4 object
    // Returns a vector containing a DHCPv4 packet header.
    vector<uint8_t> generateTestPacket2() {

        // That is only part of the header. It contains all "short" fields,
        // larger fields are constructed separately.
        uint8_t hdr[] = {
            1, 6, 6, 13,            // op, htype, hlen, hops,
            0x12, 0x34, 0x56, 0x78, // transaction-id
            0, 42, 0x80, 0x00,      // 42 secs, BROADCAST flags
            192, 0, 2, 1,           // ciaddr
            1, 2, 3, 4,             // yiaddr
            192, 0, 2, 255,         // siaddr
            255, 255, 255, 255,     // giaddr
        };

        // Initialize the vector with the header fields defined above.
        vector<uint8_t> buf(hdr, hdr + sizeof(hdr));

        // Append the large header fields.
        copy(dummyChaddr, dummyChaddr + Pkt4::MAX_CHADDR_LEN, back_inserter(buf));
        copy(dummySname, dummySname + Pkt4::MAX_SNAME_LEN, back_inserter(buf));
        copy(dummyFile, dummyFile + Pkt4::MAX_FILE_LEN, back_inserter(buf));

        // Should now have all the header, so check.  The "static_cast" is used
        // to get round an odd bug whereby the linker appears not to find the
        // definition of DHCPV4_PKT_HDR_LEN if it appears within an EXPECT_EQ().
        EXPECT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN), buf.size());

        return (buf);
    }

    /// @brief Verify that the options are correct after parsing.
    ///
    /// @param pkt A packet holding parsed options.
    void verifyParsedOptions(const Pkt4Ptr& pkt) {
        EXPECT_TRUE(pkt->getOption(12));
        EXPECT_TRUE(pkt->getOption(60));
        EXPECT_TRUE(pkt->getOption(14));
        EXPECT_TRUE(pkt->getOption(128));
        EXPECT_TRUE(pkt->getOption(254));

        boost::shared_ptr<Option> x = pkt->getOption(12);
        ASSERT_TRUE(x); // option 1 should exist
        // Option 12 is represented by the OptionString class so let's do
        // the appropriate conversion.
        OptionStringPtr option12 = boost::static_pointer_cast<OptionString>(x);
        ASSERT_TRUE(option12);
        EXPECT_EQ(12, option12->getType());  // this should be option 12
        ASSERT_EQ(3, option12->getValue().length()); // it should be of length 3
        EXPECT_EQ(5, option12->len()); // total option length 5
        EXPECT_EQ(0, memcmp(&option12->getValue()[0], v4_opts + 2, 3)); // data len=3

        x = pkt->getOption(14);
        ASSERT_TRUE(x); // option 14 should exist
        // Option 14 is represented by the OptionString class so let's do
        // the appropriate conversion.
        OptionStringPtr option14 = boost::static_pointer_cast<OptionString>(x);
        ASSERT_TRUE(option14);
        EXPECT_EQ(14, option14->getType());  // this should be option 14
        ASSERT_EQ(3, option14->getValue().length()); // it should be of length 3
        EXPECT_EQ(5, option14->len()); // total option length 5
        EXPECT_EQ(0, memcmp(&option14->getValue()[0], v4_opts + 7, 3)); // data len=3

        x = pkt->getOption(60);
        ASSERT_TRUE(x); // option 60 should exist
        EXPECT_EQ(60, x->getType());  // this should be option 60
        ASSERT_EQ(3, x->getData().size()); // it should be of length 3
        EXPECT_EQ(5, x->len()); // total option length 5
        EXPECT_EQ(0, memcmp(&x->getData()[0], v4_opts + 15, 3)); // data len=3

        x = pkt->getOption(128);
        ASSERT_TRUE(x); // option 3 should exist
        EXPECT_EQ(128, x->getType());  // this should be option 254
        ASSERT_EQ(3, x->getData().size()); // it should be of length 3
        EXPECT_EQ(5, x->len()); // total option length 5
        EXPECT_EQ(0, memcmp(&x->getData()[0], v4_opts + 20, 3)); // data len=3

        x = pkt->getOption(254);
        ASSERT_TRUE(x); // option 3 should exist
        EXPECT_EQ(254, x->getType());  // this should be option 254
        ASSERT_EQ(3, x->getData().size()); // it should be of length 3
        EXPECT_EQ(5, x->len()); // total option length 5
        EXPECT_EQ(0, memcmp(&x->getData()[0], v4_opts + 25, 3)); // data len=3
    }

};


TEST_F(Pkt4Test, constructor) {

    ASSERT_EQ(236U, static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN) );
    scoped_ptr<Pkt4> pkt;

    // Just some dummy payload.
    uint8_t testData[250];
    for (int i = 0; i < 250; i++) {
        testData[i] = i;
    }

    // Positive case1. Normal received packet.
    EXPECT_NO_THROW(pkt.reset(new Pkt4(testData, Pkt4::DHCPV4_PKT_HDR_LEN)));

    EXPECT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN), pkt->len());

    EXPECT_NO_THROW(pkt.reset());

    // Positive case2. Normal outgoing packet.
    EXPECT_NO_THROW(pkt.reset(new Pkt4(DHCPDISCOVER, 0xffffffff)));

    // DHCPv4 packet must be at least 236 bytes long, with Message Type
    // Option taking extra 3 bytes it is 239
    EXPECT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN) + 3, pkt->len());
    EXPECT_EQ(DHCPDISCOVER, pkt->getType());
    EXPECT_EQ(0xffffffff, pkt->getTransid());
    EXPECT_NO_THROW(pkt.reset());

    // Negative case. Should drop truncated messages.
    EXPECT_THROW(
        pkt.reset(new Pkt4(testData, Pkt4::DHCPV4_PKT_HDR_LEN - 1)),
        OutOfRange
    );
}


TEST_F(Pkt4Test, fixedFields) {

    boost::shared_ptr<Pkt4> pkt = generateTestPacket1();

    // OK, let's check packet values
    EXPECT_EQ(dummyOp, pkt->getOp());
    EXPECT_EQ(dummyHtype, pkt->getHtype());
    EXPECT_EQ(dummyHlen, pkt->getHlen());
    EXPECT_EQ(dummyHops, pkt->getHops());
    EXPECT_EQ(dummyTransid, pkt->getTransid());
    EXPECT_EQ(dummySecs, pkt->getSecs());
    EXPECT_EQ(dummyFlags, pkt->getFlags());

    EXPECT_EQ(dummyCiaddr, pkt->getCiaddr());
    EXPECT_EQ(dummyYiaddr, pkt->getYiaddr());
    EXPECT_EQ(dummySiaddr, pkt->getSiaddr());
    EXPECT_EQ(dummyGiaddr, pkt->getGiaddr());

    // Chaddr contains link-layer addr (MAC). It is no longer always 16 bytes
    // long and its length depends on hlen value (it is up to 16 bytes now).
    ASSERT_EQ(pkt->getHWAddr()->hwaddr_.size(), dummyHlen);
    EXPECT_EQ(0, memcmp(dummyChaddr, &pkt->getHWAddr()->hwaddr_[0], dummyHlen));

    EXPECT_EQ(0, memcmp(dummySname, &pkt->getSname()[0], 64));

    EXPECT_EQ(0, memcmp(dummyFile, &pkt->getFile()[0], 128));

    EXPECT_EQ(DHCPDISCOVER, pkt->getType());
}

TEST_F(Pkt4Test, fixedFieldsPack) {
    boost::shared_ptr<Pkt4> pkt = generateTestPacket1();
    vector<uint8_t> expectedFormat = generateTestPacket2();

    EXPECT_NO_THROW(
        pkt->pack();
    );

    // Minimum packet size is 236 bytes + 3 bytes of mandatory
    // DHCP Message Type Option
    ASSERT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN) + 3, pkt->len());

    // Redundant but MUCH easier for debug in gdb
    const uint8_t* exp = &expectedFormat[0];
    const uint8_t* got = static_cast<const uint8_t*>(pkt->getBuffer().getData());

    EXPECT_EQ(0, memcmp(exp, got, Pkt4::DHCPV4_PKT_HDR_LEN));
}

/// TODO Uncomment when ticket #1226 is implemented
TEST_F(Pkt4Test, fixedFieldsUnpack) {
    vector<uint8_t> expectedFormat = generateTestPacket2();

    expectedFormat.push_back(0x63); // magic cookie
    expectedFormat.push_back(0x82);
    expectedFormat.push_back(0x53);
    expectedFormat.push_back(0x63);

    expectedFormat.push_back(0x35); // message-type
    expectedFormat.push_back(0x1);
    expectedFormat.push_back(0x1);

    boost::shared_ptr<Pkt4> pkt(new Pkt4(&expectedFormat[0],
                                         expectedFormat.size()));;


    EXPECT_NO_THROW(
        pkt->unpack()
    );

    // OK, let's check packet values
    EXPECT_EQ(dummyOp, pkt->getOp());
    EXPECT_EQ(dummyHtype, pkt->getHtype());
    EXPECT_EQ(dummyHlen, pkt->getHlen());
    EXPECT_EQ(dummyHops, pkt->getHops());
    EXPECT_EQ(dummyTransid, pkt->getTransid());
    EXPECT_EQ(dummySecs, pkt->getSecs());
    EXPECT_EQ(dummyFlags, pkt->getFlags());

    EXPECT_EQ(dummyCiaddr, pkt->getCiaddr());
    EXPECT_EQ("1.2.3.4", pkt->getYiaddr().toText());
    EXPECT_EQ("192.0.2.255", pkt->getSiaddr().toText());
    EXPECT_EQ("255.255.255.255", pkt->getGiaddr().toText());

    // chaddr is always 16 bytes long and contains link-layer addr (MAC)
    EXPECT_EQ(0, memcmp(dummyChaddr, &pkt->getHWAddr()->hwaddr_[0], dummyHlen));

    ASSERT_EQ(static_cast<size_t>(Pkt4::MAX_SNAME_LEN), pkt->getSname().size());
    EXPECT_EQ(0, memcmp(dummySname, &pkt->getSname()[0], Pkt4::MAX_SNAME_LEN));

    ASSERT_EQ(static_cast<size_t>(Pkt4::MAX_FILE_LEN), pkt->getFile().size());
    EXPECT_EQ(0, memcmp(dummyFile, &pkt->getFile()[0], Pkt4::MAX_FILE_LEN));

    EXPECT_EQ(DHCPDISCOVER, pkt->getType());
}

// This test is for hardware addresses (htype, hlen and chaddr fields)
TEST_F(Pkt4Test, hwAddr) {

    vector<uint8_t> mac;
    uint8_t expectedChaddr[Pkt4::MAX_CHADDR_LEN];

    // We resize vector to specified length. It is more natural for fixed-length
    // field, than clear it (shrink size to 0) and push_back each element
    // (growing length back to MAX_CHADDR_LEN).
    mac.resize(Pkt4::MAX_CHADDR_LEN);

    scoped_ptr<Pkt4> pkt;
    // let's test each hlen, from 0 till 16
    for (int macLen = 0; macLen < Pkt4::MAX_CHADDR_LEN; macLen++) {
        for (int i = 0; i < Pkt4::MAX_CHADDR_LEN; i++) {
            mac[i] = 0;
            expectedChaddr[i] = 0;
        }
        for (int i = 0; i < macLen; i++) {
            mac[i] = 128 + i;
            expectedChaddr[i] = 128 + i;
        }

        // type and transaction doesn't matter in this test
        pkt.reset(new Pkt4(DHCPOFFER, 1234));
        pkt->setHWAddr(255 - macLen * 10, // just weird htype
                       macLen,
                       mac);
        EXPECT_EQ(0, memcmp(expectedChaddr, &pkt->getHWAddr()->hwaddr_[0],
                            Pkt4::MAX_CHADDR_LEN));

        EXPECT_NO_THROW(
            pkt->pack();
        );

        // CHADDR starts at offset 28 in DHCP packet
        const uint8_t* ptr =
            static_cast<const uint8_t*>(pkt->getBuffer().getData()) + 28;

        EXPECT_EQ(0, memcmp(ptr, expectedChaddr, Pkt4::MAX_CHADDR_LEN));

        pkt.reset();
    }

    /// TODO: extend this test once options support is implemented. HW address
    /// longer than 16 bytes should be stored in client-identifier option
}

TEST_F(Pkt4Test, msgTypes) {

    struct msgType {
        uint8_t dhcp;
        uint8_t bootp;
    };

    msgType types[] = {
        {DHCPDISCOVER, BOOTREQUEST},
        {DHCPOFFER, BOOTREPLY},
        {DHCPREQUEST, BOOTREQUEST},
        {DHCPDECLINE, BOOTREQUEST},
        {DHCPACK, BOOTREPLY},
        {DHCPNAK, BOOTREPLY},
        {DHCPRELEASE, BOOTREQUEST},
        {DHCPINFORM, BOOTREQUEST},
        {DHCPLEASEQUERY, BOOTREQUEST},
        {DHCPLEASEUNASSIGNED, BOOTREPLY},
        {DHCPLEASEUNKNOWN, BOOTREPLY},
        {DHCPLEASEACTIVE, BOOTREPLY}
    };

    scoped_ptr<Pkt4> pkt;
    for (int i = 0; i < sizeof(types) / sizeof(msgType); i++) {
        pkt.reset(new Pkt4(types[i].dhcp, 0));
        EXPECT_EQ(types[i].dhcp, pkt->getType());
        EXPECT_EQ(types[i].bootp, pkt->getOp());
        pkt.reset();
    }

    EXPECT_THROW(
        pkt.reset(new Pkt4(100, 0)), // There's no message type 100
        OutOfRange
    );
}

// This test verifies handling of sname field
TEST_F(Pkt4Test, sname) {

    uint8_t sname[Pkt4::MAX_SNAME_LEN];

    scoped_ptr<Pkt4> pkt;
    // Let's test each sname length, from 0 till 64
    for (int snameLen = 0; snameLen < Pkt4::MAX_SNAME_LEN; ++snameLen) {
        for (int i = 0; i < snameLen; ++i) {
            sname[i] = i + 1;
        }
        for (int i = snameLen; i < Pkt4::MAX_SNAME_LEN; ++i) {
            sname[i] = 0;
        }

        // Type and transaction doesn't matter in this test
        pkt.reset(new Pkt4(DHCPOFFER, 1234));
        pkt->setSname(sname, snameLen);

        EXPECT_EQ(0, memcmp(sname, &pkt->getSname()[0], Pkt4::MAX_SNAME_LEN));

        EXPECT_NO_THROW(
            pkt->pack();
        );

        // SNAME starts at offset 44 in DHCP packet
        const uint8_t* ptr =
            static_cast<const uint8_t*>(pkt->getBuffer().getData()) + 44;
        EXPECT_EQ(0, memcmp(ptr, sname, Pkt4::MAX_SNAME_LEN));

        pkt.reset();
    }

    // Check that a null argument generates an exception.
    Pkt4 pkt4(DHCPOFFER, 1234);
    EXPECT_THROW(pkt4.setSname(NULL, Pkt4::MAX_SNAME_LEN), InvalidParameter);
    EXPECT_THROW(pkt4.setSname(NULL, 0), InvalidParameter);
}

TEST_F(Pkt4Test, file) {

    uint8_t file[Pkt4::MAX_FILE_LEN];

    scoped_ptr<Pkt4> pkt;
    // Let's test each file length, from 0 till 128.
    for (int fileLen = 0; fileLen < Pkt4::MAX_FILE_LEN; ++fileLen) {
        for (int i = 0; i < fileLen; ++i) {
            file[i] = i + 1;
        }
        for (int i = fileLen; i < Pkt4::MAX_FILE_LEN; ++i) {
            file[i] = 0;
        }

        // Type and transaction doesn't matter in this test.
        pkt.reset(new Pkt4(DHCPOFFER, 1234));
        pkt->setFile(file, fileLen);

        EXPECT_EQ(0, memcmp(file, &pkt->getFile()[0], Pkt4::MAX_FILE_LEN));

        EXPECT_NO_THROW(
            pkt->pack();
        );

        // FILE starts at offset 108 in DHCP packet.
        const uint8_t* ptr =
            static_cast<const uint8_t*>(pkt->getBuffer().getData()) + 108;
        EXPECT_EQ(0, memcmp(ptr, file, Pkt4::MAX_FILE_LEN));

        pkt.reset();
    }

    // Check that a null argument generates an exception.
    Pkt4 pkt4(DHCPOFFER, 1234);
    EXPECT_THROW(pkt4.setFile(NULL, Pkt4::MAX_FILE_LEN), InvalidParameter);
    EXPECT_THROW(pkt4.setFile(NULL, 0), InvalidParameter);
}

TEST_F(Pkt4Test, options) {
    scoped_ptr<Pkt4> pkt(new Pkt4(DHCPOFFER, 0));

    vector<uint8_t> payload[5];
    for (int i = 0; i < 5; i++) {
        payload[i].push_back(i * 10);
        payload[i].push_back(i * 10 + 1);
        payload[i].push_back(i * 10 + 2);
    }

    boost::shared_ptr<Option> opt1(new Option(Option::V4, 12, payload[0]));
    boost::shared_ptr<Option> opt3(new Option(Option::V4, 14, payload[1]));
    boost::shared_ptr<Option> opt2(new Option(Option::V4, 60, payload[2]));
    boost::shared_ptr<Option> opt5(new Option(Option::V4,128, payload[3]));
    boost::shared_ptr<Option> opt4(new Option(Option::V4,254, payload[4]));

    pkt->addOption(opt1);
    pkt->addOption(opt2);
    pkt->addOption(opt3);
    pkt->addOption(opt4);
    pkt->addOption(opt5);

    EXPECT_TRUE(pkt->getOption(12));
    EXPECT_TRUE(pkt->getOption(60));
    EXPECT_TRUE(pkt->getOption(14));
    EXPECT_TRUE(pkt->getOption(128));
    EXPECT_TRUE(pkt->getOption(254));
    EXPECT_FALSE(pkt->getOption(127)); //  no such option

    // Options are unique in DHCPv4. It should not be possible
    // to add more than one option of the same type.
    EXPECT_THROW(
        pkt->addOption(opt1),
        BadValue
    );

    EXPECT_NO_THROW(
        pkt->pack();
    );

    const OutputBuffer& buf = pkt->getBuffer();
    // Check that all options are stored, they should take sizeof(v4_opts),
    // DHCP magic cookie (4 bytes), and OPTION_END added (just one byte)
    ASSERT_EQ(static_cast<size_t>(Pkt4::DHCPV4_PKT_HDR_LEN) +
              sizeof(DHCP_OPTIONS_COOKIE) + sizeof(v4_opts) + 1,
              buf.getLength());

    // That that this extra data actually contain our options
    const uint8_t* ptr = static_cast<const uint8_t*>(buf.getData());

    // Rewind to end of fixed part.
    ptr += Pkt4::DHCPV4_PKT_HDR_LEN + sizeof(DHCP_OPTIONS_COOKIE);

    EXPECT_EQ(0, memcmp(ptr, v4_opts, sizeof(v4_opts)));
    EXPECT_EQ(DHO_END, static_cast<uint8_t>(*(ptr + sizeof(v4_opts))));

    // delOption() checks
    EXPECT_TRUE(pkt->getOption(12));  // Sanity check: option 12 is still there
    EXPECT_TRUE(pkt->delOption(12));  // We should be able to remove it
    EXPECT_FALSE(pkt->getOption(12)); // It should not be there anymore
    EXPECT_FALSE(pkt->delOption(12)); // And removal should fail

    EXPECT_NO_THROW(pkt.reset());
}

// This test verifies that the options are unpacked from the packet correctly.
TEST_F(Pkt4Test, unpackOptions) {

    vector<uint8_t> expectedFormat = generateTestPacket2();

    expectedFormat.push_back(0x63);
    expectedFormat.push_back(0x82);
    expectedFormat.push_back(0x53);
    expectedFormat.push_back(0x63);

    for (int i = 0; i < sizeof(v4_opts); i++) {
        expectedFormat.push_back(v4_opts[i]);
    }

    // now expectedFormat contains fixed format and 5 options

    boost::shared_ptr<Pkt4> pkt(new Pkt4(&expectedFormat[0],
                                expectedFormat.size()));

    EXPECT_NO_THROW(
        pkt->unpack()
    );

    verifyParsedOptions(pkt);
}

// This test verifies that it is possible to specify custom implementation of
// the option parsing algorithm by installing a callback function.
TEST_F(Pkt4Test, unpackOptionsWithCallback) {
    vector<uint8_t> expectedFormat = generateTestPacket2();

    expectedFormat.push_back(0x63);
    expectedFormat.push_back(0x82);
    expectedFormat.push_back(0x53);
    expectedFormat.push_back(0x63);

    for (int i = 0; i < sizeof(v4_opts); i++) {
        expectedFormat.push_back(v4_opts[i]);
    }

    // now expectedFormat contains fixed format and 5 options

    boost::shared_ptr<Pkt4> pkt(new Pkt4(&expectedFormat[0],
                                expectedFormat.size()));

    CustomUnpackCallback cb;
    pkt->setCallback(boost::bind(&CustomUnpackCallback::execute, &cb,
                                 _1, _2, _3));

    ASSERT_FALSE(cb.executed_);

    EXPECT_NO_THROW(pkt->unpack());

    EXPECT_TRUE(cb.executed_);
    verifyParsedOptions(pkt);

    // Reset the indicator to perform another check: uninstall the callback.
    cb.executed_ = false;
    // By setting the callback to NULL we effectively uninstall the callback.
    pkt->setCallback(NULL);
    // Do another unpack.
    EXPECT_NO_THROW(pkt->unpack());
    // Callback should not be executed.
    EXPECT_FALSE(cb.executed_);

}

// This test verifies methods that are used for manipulating meta fields
// i.e. fields that are not part of DHCPv4 (e.g. interface name).
TEST_F(Pkt4Test, metaFields) {

    scoped_ptr<Pkt4> pkt(new Pkt4(DHCPOFFER, 1234));
    pkt->setIface("loooopback");
    pkt->setIndex(42);
    pkt->setRemoteAddr(IOAddress("1.2.3.4"));
    pkt->setLocalAddr(IOAddress("4.3.2.1"));

    EXPECT_EQ("loooopback", pkt->getIface());
    EXPECT_EQ(42, pkt->getIndex());
    EXPECT_EQ("1.2.3.4", pkt->getRemoteAddr().toText());
    EXPECT_EQ("4.3.2.1", pkt->getLocalAddr().toText());
}

TEST_F(Pkt4Test, Timestamp) {
    scoped_ptr<Pkt4> pkt(new Pkt4(DHCPOFFER, 1234));

    // Just after construction timestamp is invalid
    ASSERT_TRUE(pkt->getTimestamp().is_not_a_date_time());

    // Update packet time.
    pkt->updateTimestamp();

    // Get updated packet time.
    boost::posix_time::ptime ts_packet = pkt->getTimestamp();

    // After timestamp is updated it should be date-time.
    ASSERT_FALSE(ts_packet.is_not_a_date_time());

    // Check current time.
    boost::posix_time::ptime ts_now =
        boost::posix_time::microsec_clock::universal_time();

    // Calculate period between packet time and now.
    boost::posix_time::time_period ts_period(ts_packet, ts_now);

    // Duration should be positive or zero.
    EXPECT_TRUE(ts_period.length().total_microseconds() >= 0);
}

TEST_F(Pkt4Test, hwaddr) {
    scoped_ptr<Pkt4> pkt(new Pkt4(DHCPOFFER, 1234));
    const uint8_t hw[] = { 2, 4, 6, 8, 10, 12 }; // MAC
    const uint8_t hw_type = 123; // hardware type

    HWAddrPtr hwaddr(new HWAddr(hw, sizeof(hw), hw_type));

    // setting NULL hardware address is not allowed
    EXPECT_THROW(pkt->setHWAddr(HWAddrPtr()), BadValue);

    pkt->setHWAddr(hwaddr);

    EXPECT_EQ(hw_type, pkt->getHtype());

    EXPECT_EQ(sizeof(hw), pkt->getHlen());

    EXPECT_TRUE(hwaddr == pkt->getHWAddr());
}

// This test verifies that the packet remte and local HW address can
// be set and returned.
TEST_F(Pkt4Test, hwaddrSrcRemote) {
    scoped_ptr<Pkt4> pkt(new Pkt4(DHCPOFFER, 1234));
    const uint8_t src_hw[] = { 1, 2, 3, 4, 5, 6 };
    const uint8_t dst_hw[] = { 7, 8, 9, 10, 11, 12 };
    const uint8_t hw_type = 123;

    HWAddrPtr dst_hwaddr(new HWAddr(dst_hw, sizeof(src_hw), hw_type));
    HWAddrPtr src_hwaddr(new HWAddr(src_hw, sizeof(src_hw), hw_type));

    // Check that we can set the local address.
    EXPECT_NO_THROW(pkt->setLocalHWAddr(dst_hwaddr));
    EXPECT_TRUE(dst_hwaddr == pkt->getLocalHWAddr());

    // Check that we can set the remote address.
    EXPECT_NO_THROW(pkt->setRemoteHWAddr(src_hwaddr));
    EXPECT_TRUE(src_hwaddr == pkt->getRemoteHWAddr());

    // Can't set the NULL addres.
    EXPECT_THROW(pkt->setRemoteHWAddr(HWAddrPtr()), BadValue);
    EXPECT_THROW(pkt->setLocalHWAddr(HWAddrPtr()), BadValue);

    // Test alternative way to set local address.
    const uint8_t dst_hw2[] = { 19, 20, 21, 22, 23, 24 };
    std::vector<uint8_t> dst_hw_vec(dst_hw2, dst_hw2 + sizeof(dst_hw2));
    const uint8_t hw_type2 = 234;
    EXPECT_NO_THROW(pkt->setLocalHWAddr(hw_type2, sizeof(dst_hw2), dst_hw_vec));
    HWAddrPtr local_addr = pkt->getLocalHWAddr();
    ASSERT_TRUE(local_addr);
    EXPECT_EQ(hw_type2, local_addr->htype_);
    EXPECT_TRUE(std::equal(dst_hw_vec.begin(), dst_hw_vec.end(),
                           local_addr->hwaddr_.begin()));

    // Set remote address.
    const uint8_t src_hw2[] = { 25, 26, 27, 28, 29, 30 };
    std::vector<uint8_t> src_hw_vec(src_hw2, src_hw2 + sizeof(src_hw2));
    EXPECT_NO_THROW(pkt->setRemoteHWAddr(hw_type2, sizeof(src_hw2), src_hw_vec));
    HWAddrPtr remote_addr = pkt->getRemoteHWAddr();
    ASSERT_TRUE(remote_addr);
    EXPECT_EQ(hw_type2, remote_addr->htype_);
    EXPECT_TRUE(std::equal(src_hw_vec.begin(), src_hw_vec.end(),
                           remote_addr->hwaddr_.begin()));
}

// This test verifies that the check for a message being relayed is correct.
// It also checks that the exception is thrown if the combination of hops and
// giaddr is invalid.
TEST_F(Pkt4Test, isRelayed) {
    Pkt4 pkt(DHCPDISCOVER, 1234);
    // By default, the hops and giaddr should be 0.
    ASSERT_EQ("0.0.0.0", pkt.getGiaddr().toText());
    ASSERT_EQ(0, pkt.getHops());
    // For hops = 0 and giaddr = 0, the message is non-relayed.
    EXPECT_FALSE(pkt.isRelayed());
    // Set giaddr but leave hops = 0. This should result in exception.
    pkt.setGiaddr(IOAddress("10.0.0.1"));
    EXPECT_THROW(pkt.isRelayed(), isc::BadValue);
    // Set hops. Now both hops and giaddr is set. The message is relayed.
    pkt.setHops(10);
    EXPECT_TRUE(pkt.isRelayed());
    // Set giaddr to 0. For hops being set to non-zero value the function
    // should throw an exception.
    pkt.setGiaddr(IOAddress("0.0.0.0"));
    EXPECT_THROW(pkt.isRelayed(), isc::BadValue);
}

// Tests whether a packet can be assigned to a class and later
// checked if it belongs to a given class
TEST_F(Pkt4Test, clientClasses) {
    Pkt4 pkt(DHCPOFFER, 1234);

    // Default values (do not belong to any class)
    EXPECT_FALSE(pkt.inClass(DOCSIS3_CLASS_EROUTER));
    EXPECT_FALSE(pkt.inClass(DOCSIS3_CLASS_MODEM));
    EXPECT_TRUE(pkt.classes_.empty());

    // Add to the first class
    pkt.addClass(DOCSIS3_CLASS_EROUTER);
    EXPECT_TRUE(pkt.inClass(DOCSIS3_CLASS_EROUTER));
    EXPECT_FALSE(pkt.inClass(DOCSIS3_CLASS_MODEM));
    ASSERT_FALSE(pkt.classes_.empty());

    // Add to a second class
    pkt.addClass(DOCSIS3_CLASS_MODEM);
    EXPECT_TRUE(pkt.inClass(DOCSIS3_CLASS_EROUTER));
    EXPECT_TRUE(pkt.inClass(DOCSIS3_CLASS_MODEM));

    // Check that it's ok to add to the same class repeatedly
    EXPECT_NO_THROW(pkt.addClass("foo"));
    EXPECT_NO_THROW(pkt.addClass("foo"));
    EXPECT_NO_THROW(pkt.addClass("foo"));

    // Check that the packet belongs to 'foo'
    EXPECT_TRUE(pkt.inClass("foo"));
}

// Tests whether MAC can be obtained and that MAC sources are not
// confused.
TEST_F(Pkt4Test, getMAC) {
    Pkt4 pkt(DHCPOFFER, 1234);

    // DHCPv4 packet by default doens't have MAC address specified.
    EXPECT_FALSE(pkt.getMAC(Pkt::MAC_SOURCE_ANY));
    EXPECT_FALSE(pkt.getMAC(Pkt::MAC_SOURCE_RAW));

    // Let's invent a MAC
    const uint8_t hw[] = { 2, 4, 6, 8, 10, 12 }; // MAC
    const uint8_t hw_type = 123; // hardware type
    HWAddrPtr dummy_hwaddr(new HWAddr(hw, sizeof(hw), hw_type));

    // Now let's pretend that we obtained it from raw sockets
    pkt.setRemoteHWAddr(dummy_hwaddr);

    // Now we should be able to get something
    ASSERT_TRUE(pkt.getMAC(Pkt::MAC_SOURCE_ANY));
    ASSERT_TRUE(pkt.getMAC(Pkt::MAC_SOURCE_RAW));

    // Check that the returned MAC is indeed the expected one
    ASSERT_TRUE(*dummy_hwaddr == *pkt.getMAC(Pkt::MAC_SOURCE_ANY));
    ASSERT_TRUE(*dummy_hwaddr == *pkt.getMAC(Pkt::MAC_SOURCE_RAW));
}

} // end of anonymous namespace