dhcp4_srv.cc 82.9 KB
Newer Older
1
// Copyright (C) 2011-2015 Internet Systems Consortium, Inc. ("ISC")
2 3 4 5 6 7 8 9 10 11 12 13 14
//
// 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.

15
#include <config.h>
16
#include <asiolink/io_address.h>
17
#include <dhcp/dhcp4.h>
18 19
#include <dhcp/duid.h>
#include <dhcp/hwaddr.h>
20
#include <dhcp/iface_mgr.h>
21
#include <dhcp/option4_addrlst.h>
22
#include <dhcp/option_int.h>
23
#include <dhcp/option_int_array.h>
24
#include <dhcp/option_vendor.h>
25
#include <dhcp/option_string.h>
26
#include <dhcp/pkt4.h>
27
#include <dhcp/docsis3_option_defs.h>
28 29
#include <dhcp4/dhcp4_log.h>
#include <dhcp4/dhcp4_srv.h>
30 31
#include <dhcpsrv/addr_utilities.h>
#include <dhcpsrv/callout_handle_store.h>
32
#include <dhcpsrv/cfgmgr.h>
33
#include <dhcpsrv/cfg_subnets4.h>
34 35 36
#include <dhcpsrv/lease_mgr.h>
#include <dhcpsrv/lease_mgr_factory.h>
#include <dhcpsrv/subnet.h>
37
#include <dhcpsrv/subnet_selector.h>
38
#include <dhcpsrv/utils.h>
39
#include <dhcpsrv/utils.h>
40
#include <hooks/callout_handle.h>
41
#include <hooks/hooks_manager.h>
42
#include <util/strutil.h>
43

44
#include <asio.hpp>
45
#include <boost/bind.hpp>
46
#include <boost/foreach.hpp>
47
#include <boost/shared_ptr.hpp>
48 49 50

#include <iomanip>

51 52
using namespace isc;
using namespace isc::asiolink;
53
using namespace isc::dhcp;
54
using namespace isc::dhcp_ddns;
55
using namespace isc::hooks;
56 57
using namespace isc::log;
using namespace std;
58

59
/// Structure that holds registered hook indexes
60 61
struct Dhcp4Hooks {
    int hook_index_buffer4_receive_;///< index for "buffer4_receive" hook point
62 63
    int hook_index_pkt4_receive_;   ///< index for "pkt4_receive" hook point
    int hook_index_subnet4_select_; ///< index for "subnet4_select" hook point
64
    int hook_index_lease4_release_; ///< index for "lease4_release" hook point
65
    int hook_index_pkt4_send_;      ///< index for "pkt4_send" hook point
66
    int hook_index_buffer4_send_;   ///< index for "buffer4_send" hook point
67

68 69 70
    /// Constructor that registers hook points for DHCPv4 engine
    Dhcp4Hooks() {
        hook_index_buffer4_receive_= HooksManager::registerHook("buffer4_receive");
71 72 73
        hook_index_pkt4_receive_   = HooksManager::registerHook("pkt4_receive");
        hook_index_subnet4_select_ = HooksManager::registerHook("subnet4_select");
        hook_index_pkt4_send_      = HooksManager::registerHook("pkt4_send");
74 75
        hook_index_lease4_release_ = HooksManager::registerHook("lease4_release");
        hook_index_buffer4_send_   = HooksManager::registerHook("buffer4_send");
76 77 78 79 80 81 82
    }
};

// Declare a Hooks object. As this is outside any function or method, it
// will be instantiated (and the constructor run) when the module is loaded.
// As a result, the hook indexes will be defined before any method in this
// module is called.
83
Dhcp4Hooks Hooks;
84

85 86 87
namespace isc {
namespace dhcp {

88
Dhcpv4Exchange::Dhcpv4Exchange(const AllocEnginePtr& alloc_engine,
89 90
                               const Pkt4Ptr& query,
                               const Subnet4Ptr& subnet)
91 92
    : alloc_engine_(alloc_engine), query_(query), resp_(),
      context_(new AllocEngine::ClientContext4()) {
93

94 95 96 97 98 99 100 101
    if (!alloc_engine_) {
        isc_throw(BadValue, "alloc_engine value must not be NULL"
                  " when creating an instance of the Dhcpv4Exchange");
    }

    if (!query_) {
        isc_throw(BadValue, "query value must not be NULL when"
                  " creating an instance of the Dhcpv4Exchange");
102 103
    }

104 105 106
    // Create response message.
    initResponse();
    // Select subnet for the query message.
107
    context_->subnet_ = subnet;
108
    // Hardware address.
109
    context_->hwaddr_ = query->getHWAddr();
110 111 112
    // Client Identifier
    OptionPtr opt_clientid = query->getOption(DHO_DHCP_CLIENT_IDENTIFIER);
    if (opt_clientid) {
113
        context_->clientid_.reset(new ClientId(opt_clientid->getData()));
114 115
    }
    // Check for static reservations.
116
    alloc_engine->findReservation(*context_);
117 118
};

119
void
120
Dhcpv4Exchange::initResponse() {
121 122 123 124 125 126 127 128 129 130 131 132
    uint8_t resp_type = 0;
    switch (getQuery()->getType()) {
    case DHCPDISCOVER:
        resp_type = DHCPOFFER;
        break;
    case DHCPREQUEST:
    case DHCPINFORM:
        resp_type = DHCPACK;
        break;
    default:
        ;
    }
133
    // Only create a response if one is required.
134 135
    if (resp_type > 0) {
        resp_.reset(new Pkt4(resp_type, getQuery()->getTransid()));
136 137 138 139 140 141 142 143 144
        copyDefaultFields();
    }
}

void
Dhcpv4Exchange::copyDefaultFields() {
    resp_->setIface(query_->getIface());
    resp_->setIndex(query_->getIndex());

145 146
    // explicitly set this to 0
    resp_->setSiaddr(IOAddress::IPV4_ZERO_ADDRESS());
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
    // ciaddr is always 0, except for the Renew/Rebind state when it may
    // be set to the ciaddr sent by the client.
    resp_->setCiaddr(IOAddress::IPV4_ZERO_ADDRESS());
    resp_->setHops(query_->getHops());

    // copy MAC address
    resp_->setHWAddr(query_->getHWAddr());

    // relay address
    resp_->setGiaddr(query_->getGiaddr());

    // Let's copy client-id to response. See RFC6842.
    // It is possible to disable RFC6842 to keep backward compatibility
    bool echo = CfgMgr::instance().echoClientId();
    OptionPtr client_id = query_->getOption(DHO_DHCP_CLIENT_IDENTIFIER);
    if (client_id && echo) {
        resp_->addOption(client_id);
    }

    // If src/dest HW addresses are used by the packet filtering class
    // we need to copy them as well. There is a need to check that the
    // address being set is not-NULL because an attempt to set the NULL
    // HW would result in exception. If these values are not set, the
    // the default HW addresses (zeroed) should be generated by the
    // packet filtering class when creating Ethernet header for
    // outgoing packet.
    HWAddrPtr src_hw_addr = query_->getLocalHWAddr();
    if (src_hw_addr) {
        resp_->setLocalHWAddr(src_hw_addr);
    }
    HWAddrPtr dst_hw_addr = query_->getRemoteHWAddr();
    if (dst_hw_addr) {
        resp_->setRemoteHWAddr(dst_hw_addr);
    }

    // If this packet is relayed, we want to copy Relay Agent Info option
    OptionPtr rai = query_->getOption(DHO_DHCP_AGENT_OPTIONS);
    if (rai) {
        resp_->addOption(rai);
186 187 188
    }
}

189 190
const std::string Dhcpv4Srv::VENDOR_CLASS_PREFIX("VENDOR_CLASS_");

191
Dhcpv4Srv::Dhcpv4Srv(uint16_t port, const bool use_bcast,
192
                     const bool direct_response_desired)
193 194 195
    : shutdown_(true), alloc_engine_(), port_(port),
      use_bcast_(use_bcast), hook_index_pkt4_receive_(-1),
      hook_index_subnet4_select_(-1), hook_index_pkt4_send_(-1) {
196

197
    LOG_DEBUG(dhcp4_logger, DBG_DHCP4_START, DHCP4_OPEN_SOCKET).arg(port);
198
    try {
199 200 201
        // Port 0 is used for testing purposes where we don't open broadcast
        // capable sockets. So, set the packet filter handling direct traffic
        // only if we are in non-test mode.
202
        if (port) {
203 204 205 206 207 208 209 210
            // First call to instance() will create IfaceMgr (it's a singleton)
            // it may throw something if things go wrong.
            // The 'true' value of the call to setMatchingPacketFilter imposes
            // that IfaceMgr will try to use the mechanism to respond directly
            // to the client which doesn't have address assigned. This capability
            // may be lacking on some OSes, so there is no guarantee that server
            // will be able to respond directly.
            IfaceMgr::instance().setMatchingPacketFilter(direct_response_desired);
211
        }
212

213
        // Instantiate allocation engine
214 215
        alloc_engine_.reset(new AllocEngine(AllocEngine::ALLOC_ITERATIVE, 100,
                                            false /* false = IPv4 */));
216

217 218 219 220 221 222 223
        // Register hook points
        hook_index_pkt4_receive_   = Hooks.hook_index_pkt4_receive_;
        hook_index_subnet4_select_ = Hooks.hook_index_subnet4_select_;
        hook_index_pkt4_send_      = Hooks.hook_index_pkt4_send_;

        /// @todo call loadLibraries() when handling configuration changes

224
    } catch (const std::exception &e) {
225
        LOG_ERROR(dhcp4_logger, DHCP4_SRV_CONSTRUCT_ERROR).arg(e.what());
226 227 228
        shutdown_ = true;
        return;
    }
229

Tomek Mrugalski's avatar
Tomek Mrugalski committed
230
    shutdown_ = false;
231 232 233
}

Dhcpv4Srv::~Dhcpv4Srv() {
Tomek Mrugalski's avatar
Tomek Mrugalski committed
234
    IfaceMgr::instance().closeSockets();
235 236
}

237 238
void
Dhcpv4Srv::shutdown() {
239
    LOG_DEBUG(dhcp4_logger, DBG_DHCP4_BASIC, DHCP4_SHUTDOWN_REQUEST);
240 241 242
    shutdown_ = true;
}

243
isc::dhcp::Subnet4Ptr
244
Dhcpv4Srv::selectSubnet(const Pkt4Ptr& query) const {
245 246 247 248 249 250 251 252 253 254 255 256 257 258 259

    Subnet4Ptr subnet;

    SubnetSelector selector;
    selector.ciaddr_ = query->getCiaddr();
    selector.giaddr_ = query->getGiaddr();
    selector.local_address_ = query->getLocalAddr();
    selector.remote_address_ = query->getRemoteAddr();
    selector.client_classes_ = query->classes_;
    selector.iface_name_ = query->getIface();

    CfgMgr& cfgmgr = CfgMgr::instance();
    subnet = cfgmgr.getCurrentCfg()->getCfgSubnets4()->selectSubnet(selector);

    // Let's execute all callouts registered for subnet4_select
260
    if (HooksManager::calloutsPresent(hook_index_subnet4_select_)) {
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
        CalloutHandlePtr callout_handle = getCalloutHandle(query);

        // We're reusing callout_handle from previous calls
        callout_handle->deleteAllArguments();

        // Set new arguments
        callout_handle->setArgument("query4", query);
        callout_handle->setArgument("subnet4", subnet);
        callout_handle->setArgument("subnet4collection",
                                    cfgmgr.getCurrentCfg()->
                                    getCfgSubnets4()->getAll());

        // Call user (and server-side) callouts
        HooksManager::callCallouts(hook_index_subnet4_select_,
                                   *callout_handle);

        // Callouts decided to skip this step. This means that no subnet
        // will be selected. Packet processing will continue, but it will
        // be severely limited (i.e. only global options will be assigned)
        if (callout_handle->getSkip()) {
            LOG_DEBUG(dhcp4_logger, DBG_DHCP4_HOOKS,
                      DHCP4_HOOK_SUBNET4_SELECT_SKIP);
            return (Subnet4Ptr());
        }

        // Use whatever subnet was specified by the callout
        callout_handle->getArgument("subnet4", subnet);
    }

    return (subnet);
291 292
}

Tomek Mrugalski's avatar
Tomek Mrugalski committed
293 294
Pkt4Ptr
Dhcpv4Srv::receivePacket(int timeout) {
295 296 297
    return (IfaceMgr::instance().receive4(timeout));
}

Tomek Mrugalski's avatar
Tomek Mrugalski committed
298 299
void
Dhcpv4Srv::sendPacket(const Pkt4Ptr& packet) {
300 301 302
    IfaceMgr::instance().send(packet);
}

303 304
bool
Dhcpv4Srv::run() {
Tomek Mrugalski's avatar
Tomek Mrugalski committed
305
    while (!shutdown_) {
Tomek Mrugalski's avatar
Tomek Mrugalski committed
306
        // client's message and server's response
307
        Pkt4Ptr query;
Tomek Mrugalski's avatar
Tomek Mrugalski committed
308
        Pkt4Ptr rsp;
309

310
        try {
311 312 313 314 315 316 317 318 319 320
            // The lease database backend may install some timers for which
            // the handlers need to be executed periodically. Retrieve the
            // maximum interval at which the handlers must be executed from
            // the lease manager.
            uint32_t timeout = LeaseMgrFactory::instance().getIOServiceExecInterval();
            // If the returned value is zero it means that there are no
            // timers installed, so use a default value.
            if (timeout == 0) {
                timeout = 1000;
            }
321
            query = receivePacket(timeout);
322 323 324 325 326 327 328

        } catch (const SignalInterruptOnSelect) {
            // Packet reception interrupted because a signal has been received.
            // This is not an error because we might have received a SIGTERM,
            // SIGINT or SIGHUP which are handled by the server. For signals
            // that are not handled by the server we rely on the default
            // behavior of the system, but there is nothing we should log here.
329
        } catch (const std::exception& e) {
330
            // Log all other errors.
331 332 333
            LOG_ERROR(dhcp4_logger, DHCP4_PACKET_RECEIVE_FAIL).arg(e.what());
        }

334 335 336
        // Handle next signal received by the process. It must be called after
        // an attempt to receive a packet to properly handle server shut down.
        // The SIGTERM or SIGINT will be received prior to, or during execution
Francis Dupont's avatar
Francis Dupont committed
337 338 339 340 341 342 343
        // of select() (select is invoked by receivePacket()). When that
        // happens, select will be interrupted. The signal handler will be
        // invoked immediately after select(). The handler will set the
        // shutdown flag and cause the process to terminate before the next
        // select() function is called. If the function was called before
        // receivePacket the process could wait up to the duration of timeout
        // of select() to terminate.
344 345
        handleSignal();

346 347
        // Execute ready timers for the lease database, e.g. Lease File Cleanup.
        try {
348
            LeaseMgrFactory::instance().getIOService()->poll();
349 350 351 352 353 354

        } catch (const std::exception& ex) {
            LOG_WARN(dhcp4_logger, DHCP4_LEASE_DATABASE_TIMERS_EXEC_FAIL)
                .arg(ex.what());
        }

355
        // Timeout may be reached or signal received, which breaks select()
Francis Dupont's avatar
Francis Dupont committed
356
        // with no reception occurred
357 358 359 360
        if (!query) {
            continue;
        }

361 362 363 364 365 366 367 368 369
        // In order to parse the DHCP options, the server needs to use some
        // configuration information such as: existing option spaces, option
        // definitions etc. This is the kind of information which is not
        // available in the libdhcp, so we need to supply our own implementation
        // of the option parsing function here, which would rely on the
        // configuration data.
        query->setCallback(boost::bind(&Dhcpv4Srv::unpackOptions, this,
                                       _1, _2, _3));

370 371 372
        bool skip_unpack = false;

        // The packet has just been received so contains the uninterpreted wire
373
        // data; execute callouts registered for buffer4_receive.
374
        if (HooksManager::calloutsPresent(Hooks.hook_index_buffer4_receive_)) {
375 376 377 378 379 380 381 382 383
            CalloutHandlePtr callout_handle = getCalloutHandle(query);

            // Delete previously set arguments
            callout_handle->deleteAllArguments();

            // Pass incoming packet as argument
            callout_handle->setArgument("query4", query);

            // Call callouts
Tomek Mrugalski's avatar
Tomek Mrugalski committed
384 385
            HooksManager::callCallouts(Hooks.hook_index_buffer4_receive_,
                                       *callout_handle);
386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401

            // Callouts decided to skip the next processing step. The next
            // processing step would to parse the packet, so skip at this
            // stage means that callouts did the parsing already, so server
            // should skip parsing.
            if (callout_handle->getSkip()) {
                LOG_DEBUG(dhcp4_logger, DBG_DHCP4_HOOKS, DHCP4_HOOK_BUFFER_RCVD_SKIP);
                skip_unpack = true;
            }

            callout_handle->getArgument("query4", query);
        }

        // Unpack the packet information unless the buffer4_receive callouts
        // indicated they did it
        if (!skip_unpack) {
Tomek Mrugalski's avatar
Tomek Mrugalski committed
402 403 404
            try {
                query->unpack();
            } catch (const std::exception& e) {
405
                // Failed to parse the packet.
406 407
                LOG_DEBUG(bad_packet_logger, DBG_DHCP4_DETAIL,
                          DHCP4_PACKET_DROP_0001)
408 409
                    .arg(query->getLabel())
                    .arg(e.what());
410 411
                continue;
            }
412
        }
413

Tomek Mrugalski's avatar
Tomek Mrugalski committed
414 415 416
        // Assign this packet to one or more classes if needed. We need to do
        // this before calling accept(), because getSubnet4() may need client
        // class information.
417 418
        classifyPacket(query);

419 420 421
        // Check whether the message should be further processed or discarded.
        // There is no need to log anything here. This function logs by itself.
        if (!accept(query)) {
422
            continue;
423
        }
424

425
        // We have sanity checked (in accept() that the Message Type option
426 427
        // exists, so we can safely get it here.
        int type = query->getType();
428
        LOG_DEBUG(dhcp4_logger, DBG_DHCP4_DETAIL, DHCP4_PACKET_RECEIVED)
429
            .arg(serverReceivedPacketName(type))
430
            .arg(type)
431 432
            .arg(query->getIface());
        LOG_DEBUG(dhcp4_logger, DBG_DHCP4_DETAIL_DATA, DHCP4_QUERY_DATA)
433
            .arg(type)
434 435
            .arg(query->toText());

Tomek Mrugalski's avatar
Tomek Mrugalski committed
436
        // Let's execute all callouts registered for pkt4_receive
437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456
        if (HooksManager::calloutsPresent(hook_index_pkt4_receive_)) {
            CalloutHandlePtr callout_handle = getCalloutHandle(query);

            // Delete previously set arguments
            callout_handle->deleteAllArguments();

            // Pass incoming packet as argument
            callout_handle->setArgument("query4", query);

            // Call callouts
            HooksManager::callCallouts(hook_index_pkt4_receive_,
                                       *callout_handle);

            // Callouts decided to skip the next processing step. The next
            // processing step would to process the packet, so skip at this
            // stage means drop.
            if (callout_handle->getSkip()) {
                LOG_DEBUG(dhcp4_logger, DBG_DHCP4_HOOKS, DHCP4_HOOK_PACKET_RCVD_SKIP);
                continue;
            }
457

458 459
            callout_handle->getArgument("query4", query);
        }
460

461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482
        try {
            switch (query->getType()) {
            case DHCPDISCOVER:
                rsp = processDiscover(query);
                break;

            case DHCPREQUEST:
                // Note that REQUEST is used for many things in DHCPv4: for
                // requesting new leases, renewing existing ones and even
                // for rebinding.
                rsp = processRequest(query);
                break;

            case DHCPRELEASE:
                processRelease(query);
                break;

            case DHCPDECLINE:
                processDecline(query);
                break;

            case DHCPINFORM:
483
                rsp = processInform(query);
484 485 486 487 488 489 490
                break;

            default:
                // Only action is to output a message if debug is enabled,
                // and that is covered by the debug statement before the
                // "switch" statement.
                ;
491
            }
492 493
        } catch (const isc::Exception& e) {

494 495 496 497 498 499
            // Catch-all exception (at least for ones based on the isc Exception
            // class, which covers more or less all that are explicitly raised
            // in the Kea code).  Just log the problem and ignore the packet.
            // (The problem is logged as a debug message because debug is
            // disabled by default - it prevents a DDOS attack based on the
            // sending of problem packets.)
500 501 502 503 504
            if (dhcp4_logger.isDebugEnabled(DBG_DHCP4_BASIC)) {
                std::string source = "unknown";
                HWAddrPtr hwptr = query->getHWAddr();
                if (hwptr) {
                    source = hwptr->toText();
505
                }
506 507
                LOG_DEBUG(bad_packet_logger, DBG_DHCP4_BASIC,
                          DHCP4_PACKET_DROP_0007)
508 509
                    .arg(query->getLabel())
                    .arg(e.what());
510
            }
511
        }
512

513 514 515
        if (!rsp) {
            continue;
        }
516

517

518 519
        // Specifies if server should do the packing
        bool skip_pack = false;
520

Tomek Mrugalski's avatar
Tomek Mrugalski committed
521
        // Execute all callouts registered for pkt4_send
522 523
        if (HooksManager::calloutsPresent(hook_index_pkt4_send_)) {
            CalloutHandlePtr callout_handle = getCalloutHandle(query);
524

525 526
            // Delete all previous arguments
            callout_handle->deleteAllArguments();
527

528 529
            // Clear skip flag if it was set in previous callouts
            callout_handle->setSkip(false);
530

531 532
            // Set our response
            callout_handle->setArgument("response4", rsp);
533

534 535 536
            // Call all installed callouts
            HooksManager::callCallouts(hook_index_pkt4_send_,
                                       *callout_handle);
537

538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559
            // Callouts decided to skip the next processing step. The next
            // processing step would to send the packet, so skip at this
            // stage means "drop response".
            if (callout_handle->getSkip()) {
                LOG_DEBUG(dhcp4_logger, DBG_DHCP4_HOOKS, DHCP4_HOOK_PACKET_SEND_SKIP);
                skip_pack = true;
            }
        }

        if (!skip_pack) {
            try {
                rsp->pack();
            } catch (const std::exception& e) {
                LOG_ERROR(dhcp4_logger, DHCP4_PACKET_SEND_FAIL)
                    .arg(e.what());
            }
        }

        try {
            // Now all fields and options are constructed into output wire buffer.
            // Option objects modification does not make sense anymore. Hooks
            // can only manipulate wire buffer at this stage.
Tomek Mrugalski's avatar
Tomek Mrugalski committed
560
            // Let's execute all callouts registered for buffer4_send
561
            if (HooksManager::calloutsPresent(Hooks.hook_index_buffer4_send_)) {
562
                CalloutHandlePtr callout_handle = getCalloutHandle(query);
563

564 565
                // Delete previously set arguments
                callout_handle->deleteAllArguments();
566

567 568
                // Pass incoming packet as argument
                callout_handle->setArgument("response4", rsp);
569

570
                // Call callouts
Tomek Mrugalski's avatar
Tomek Mrugalski committed
571 572
                HooksManager::callCallouts(Hooks.hook_index_buffer4_send_,
                                           *callout_handle);
573

574 575 576 577
                // Callouts decided to skip the next processing step. The next
                // processing step would to parse the packet, so skip at this
                // stage means drop.
                if (callout_handle->getSkip()) {
Tomek Mrugalski's avatar
Tomek Mrugalski committed
578 579
                    LOG_DEBUG(dhcp4_logger, DBG_DHCP4_HOOKS,
                              DHCP4_HOOK_BUFFER_SEND_SKIP);
580
                    continue;
581
                }
582 583

                callout_handle->getArgument("response4", rsp);
584
            }
585 586 587 588 589 590 591 592 593

            LOG_DEBUG(dhcp4_logger, DBG_DHCP4_DETAIL_DATA,
                      DHCP4_RESPONSE_DATA)
                .arg(static_cast<int>(rsp->getType())).arg(rsp->toText());

            sendPacket(rsp);
        } catch (const std::exception& e) {
            LOG_ERROR(dhcp4_logger, DHCP4_PACKET_SEND_FAIL)
                .arg(e.what());
594
        }
595 596 597 598 599
    }

    return (true);
}

600
string
601
Dhcpv4Srv::srvidToString(const OptionPtr& srvid) {
602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617
    if (!srvid) {
        isc_throw(BadValue, "NULL pointer passed to srvidToString()");
    }
    boost::shared_ptr<Option4AddrLst> generated =
        boost::dynamic_pointer_cast<Option4AddrLst>(srvid);
    if (!srvid) {
        isc_throw(BadValue, "Pointer to invalid option passed to srvidToString()");
    }

    Option4AddrLst::AddressContainer addrs = generated->getAddresses();
    if (addrs.size() != 1) {
        isc_throw(BadValue, "Malformed option passed to srvidToString(). "
                  << "Expected to contain a single IPv4 address.");
    }

    return (addrs[0].toText());
618 619
}

620
isc::dhcp_ddns::D2Dhcid
621 622 623 624 625 626 627 628 629
Dhcpv4Srv::computeDhcid(const Lease4Ptr& lease) {
    if (!lease) {
        isc_throw(DhcidComputeError, "a pointer to the lease must be not"
                  " NULL to compute DHCID");

    } else if (lease->hostname_.empty()) {
        isc_throw(DhcidComputeError, "unable to compute the DHCID for the"
                  " lease which has empty hostname set");

630 631
    }

632 633 634 635 636 637 638 639 640
    // In order to compute DHCID the client's hostname must be encoded in
    // canonical wire format. It is unlikely that the FQDN is malformed
    // because it is validated by the classes which encapsulate options
    // carrying client FQDN. However, if the client name was carried in the
    // Hostname option it is more likely as it carries the hostname as a
    // regular string.
    std::vector<uint8_t> fqdn_wire;
    try {
        OptionDataTypeUtil::writeFqdn(lease->hostname_, fqdn_wire, true);
641

642 643 644
    } catch (const Exception& ex) {
        isc_throw(DhcidComputeError, "unable to compute DHCID because the"
                  " hostname: " << lease->hostname_ << " is invalid");
645 646

    }
647 648 649

    // Prefer client id to HW address to compute DHCID. If Client Id is
    // NULL, use HW address.
650
    try {
651 652 653 654
        if (lease->client_id_) {
            return (D2Dhcid(lease->client_id_->getClientId(), fqdn_wire));

        } else {
655
            return (D2Dhcid(lease->hwaddr_, fqdn_wire));
656
        }
657
    } catch (const Exception& ex) {
658 659
        isc_throw(DhcidComputeError, "unable to compute DHCID: "
                  << ex.what());
660

661
    }
662 663 664

}

665
void
666
Dhcpv4Srv::appendServerID(Dhcpv4Exchange& ex) {
667 668 669
    // The source address for the outbound message should have been set already.
    // This is the address that to the best of the server's knowledge will be
    // available from the client.
670 671
    /// @todo: perhaps we should consider some more sophisticated server id
    /// generation, but for the current use cases, it should be ok.
672 673 674
    OptionPtr opt_srvid(new Option4AddrLst(DHO_DHCP_SERVER_IDENTIFIER,
                                           ex.getResponse()->getLocalAddr()));
    ex.getResponse()->addOption(opt_srvid);
675 676
}

677
void
678
Dhcpv4Srv::appendRequestedOptions(Dhcpv4Exchange& ex) {
679 680
    // Get the subnet relevant for the client. We will need it
    // to get the options associated with it.
681
    Subnet4Ptr subnet = ex.getContext()->subnet_;
682 683 684 685 686 687 688
    // If we can't find the subnet for the client there is no way
    // to get the options to be sent to a client. We don't log an
    // error because it will be logged by the assignLease method
    // anyway.
    if (!subnet) {
        return;
    }
689

690 691
    Pkt4Ptr query = ex.getQuery();

692 693 694
    // try to get the 'Parameter Request List' option which holds the
    // codes of requested options.
    OptionUint8ArrayPtr option_prl = boost::dynamic_pointer_cast<
695
        OptionUint8Array>(query->getOption(DHO_DHCP_PARAMETER_REQUEST_LIST));
696 697 698 699 700
    // If there is no PRL option in the message from the client then
    // there is nothing to do.
    if (!option_prl) {
        return;
    }
701

702 703
    Pkt4Ptr resp = ex.getResponse();

704 705 706 707 708 709
    // Get the codes of requested options.
    const std::vector<uint8_t>& requested_opts = option_prl->getValues();
    // For each requested option code get the instance of the option
    // to be returned to the client.
    for (std::vector<uint8_t>::const_iterator opt = requested_opts.begin();
         opt != requested_opts.end(); ++opt) {
710
        if (!resp->getOption(*opt)) {
711
            OptionDescriptor desc = subnet->getCfgOption()->get("dhcp4", *opt);
712
            if (desc.option_) {
713
                resp->addOption(desc.option_);
714
            }
715 716
        }
    }
Tomek Mrugalski's avatar
Tomek Mrugalski committed
717
}
718

719
void
720
Dhcpv4Srv::appendRequestedVendorOptions(Dhcpv4Exchange& ex) {
721
    // Get the configured subnet suitable for the incoming packet.
722
    Subnet4Ptr subnet = ex.getContext()->subnet_;
723 724 725 726 727 728 729 730 731 732
    // Leave if there is no subnet matching the incoming packet.
    // There is no need to log the error message here because
    // it will be logged in the assignLease() when it fails to
    // pick the suitable subnet. We don't want to duplicate
    // error messages in such case.
    if (!subnet) {
        return;
    }

    // Try to get the vendor option
733 734
    boost::shared_ptr<OptionVendor> vendor_req = boost::dynamic_pointer_cast<
        OptionVendor>(ex.getQuery()->getOption(DHO_VIVSO_SUBOPTIONS));
735 736 737 738 739 740 741
    if (!vendor_req) {
        return;
    }

    uint32_t vendor_id = vendor_req->getVendorId();

    // Let's try to get ORO within that vendor-option
742 743
    /// @todo This is very specific to vendor-id=4491 (Cable Labs). Other
    /// vendors may have different policies.
Tomek Mrugalski's avatar
Tomek Mrugalski committed
744 745
    OptionUint8ArrayPtr oro =
        boost::dynamic_pointer_cast<OptionUint8Array>(vendor_req->getOption(DOCSIS3_V4_ORO));
746 747 748 749 750 751 752 753 754 755

    // Option ORO not found. Don't do anything then.
    if (!oro) {
        return;
    }

    boost::shared_ptr<OptionVendor> vendor_rsp(new OptionVendor(Option::V4, vendor_id));

    // Get the list of options that client requested.
    bool added = false;
756
    const std::vector<uint8_t>& requested_opts = oro->getValues();
757

Tomek Mrugalski's avatar
Tomek Mrugalski committed
758
    for (std::vector<uint8_t>::const_iterator code = requested_opts.begin();
759
         code != requested_opts.end(); ++code) {
760
        if  (!vendor_rsp->getOption(*code)) {
761 762
            OptionDescriptor desc = subnet->getCfgOption()->get(vendor_id,
                                                                *code);
763 764
            if (desc.option_) {
                vendor_rsp->addOption(desc.option_);
765 766
                added = true;
            }
767 768
        }

769
        if (added) {
770
            ex.getResponse()->addOption(vendor_rsp);
771 772
        }
    }
Tomek Mrugalski's avatar
Tomek Mrugalski committed
773
}
774

775

776
void
777
Dhcpv4Srv::appendBasicOptions(Dhcpv4Exchange& ex) {
778 779 780 781 782 783
    // Identify options that we always want to send to the
    // client (if they are configured).
    static const uint16_t required_options[] = {
        DHO_ROUTERS,
        DHO_DOMAIN_NAME_SERVERS,
        DHO_DOMAIN_NAME };
784

785 786 787 788
    static size_t required_options_size =
        sizeof(required_options) / sizeof(required_options[0]);

    // Get the subnet.
789
    Subnet4Ptr subnet = ex.getContext()->subnet_;
790 791 792 793
    if (!subnet) {
        return;
    }

794 795
    Pkt4Ptr resp = ex.getResponse();

796 797 798
    // Try to find all 'required' options in the outgoing
    // message. Those that are not present will be added.
    for (int i = 0; i < required_options_size; ++i) {
799
        OptionPtr opt = resp->getOption(required_options[i]);
800 801
        if (!opt) {
            // Check whether option has been configured.
802 803
            OptionDescriptor desc = subnet->getCfgOption()->
                get("dhcp4", required_options[i]);
804
            if (desc.option_) {
805
                resp->addOption(desc.option_);
806 807 808
            }
        }
    }
Tomek Mrugalski's avatar
Tomek Mrugalski committed
809
}
810

811
void
812
Dhcpv4Srv::processClientName(Dhcpv4Exchange& ex) {
813 814 815
    // It is possible that client has sent both Client FQDN and Hostname
    // option. In such case, server should prefer Client FQDN option and
    // ignore the Hostname option.
816
    try {
817
        Pkt4Ptr resp = ex.getResponse();
818
        Option4ClientFqdnPtr fqdn = boost::dynamic_pointer_cast<Option4ClientFqdn>
819
            (ex.getQuery()->getOption(DHO_FQDN));
820
        if (fqdn) {
821
            processClientFqdnOption(ex);
822 823

        } else {
824
            OptionStringPtr hostname = boost::dynamic_pointer_cast<OptionString>
825
                (ex.getQuery()->getOption(DHO_HOST_NAME));
826
            if (hostname) {
827
                processHostnameOption(ex);
828 829 830 831 832 833 834 835 836 837 838 839 840
            }
        }
    } catch (const Exception& ex) {
        // In some rare cases it is possible that the client's name processing
        // fails. For example, the Hostname option may be malformed, or there
        // may be an error in the server's logic which would cause multiple
        // attempts to add the same option to the response message. This
        // error message aggregates all these errors so they can be diagnosed
        // from the log. We don't want to throw an exception here because,
        // it will impact the processing of the whole packet. We rather want
        // the processing to continue, even if the client's name is wrong.
        LOG_DEBUG(dhcp4_logger, DBG_DHCP4_DETAIL_DATA, DHCP4_CLIENT_NAME_PROC_FAIL)
            .arg(ex.what());
841 842 843 844
    }
}

void
845
Dhcpv4Srv::processClientFqdnOption(Dhcpv4Exchange& ex) {
846 847 848 849
    // Obtain the FQDN option from the client's message.
    Option4ClientFqdnPtr fqdn = boost::dynamic_pointer_cast<
        Option4ClientFqdn>(ex.getQuery()->getOption(DHO_FQDN));

850 851 852 853
    // Create the DHCPv4 Client FQDN Option to be included in the server's
    // response to a client.
    Option4ClientFqdnPtr fqdn_resp(new Option4ClientFqdn(*fqdn));

854 855 856 857
    // Set the server S, N, and O flags based on client's flags and
    // current configuration.
    D2ClientMgr& d2_mgr = CfgMgr::instance().getD2ClientMgr();
    d2_mgr.adjustFqdnFlags<Option4ClientFqdn>(*fqdn, *fqdn_resp);
858

859 860 861
    // Carry over the client's E flag.
    fqdn_resp->setFlag(Option4ClientFqdn::FLAG_E,
                       fqdn->getFlag(Option4ClientFqdn::FLAG_E));
862

863
    if (ex.getContext()->host_ && !ex.getContext()->host_->getHostname().empty()) {
864 865 866
        D2ClientMgr& d2_mgr = CfgMgr::instance().getD2ClientMgr();
        fqdn_resp->setDomainName(d2_mgr.qualifyName(ex.getContext()->host_->getHostname(),
                                                    true), Option4ClientFqdn::FULL);
867

868 869 870 871 872
    } else {
        // Adjust the domain name based on domain name value and type sent by the
        // client and current configuration.
        d2_mgr.adjustDomainName<Option4ClientFqdn>(*fqdn, *fqdn_resp);
    }
873 874 875 876 877 878 879 880 881 882

    // Add FQDN option to the response message. Note that, there may be some
    // cases when server may choose not to include the FQDN option in a
    // response to a client. In such cases, the FQDN should be removed from the
    // outgoing message. In theory we could cease to include the FQDN option
    // in this function until it is confirmed that it should be included.
    // However, we include it here for simplicity. Functions used to acquire
    // lease for a client will scan the response message for FQDN and if it
    // is found they will take necessary actions to store the FQDN information
    // in the lease database as well as to generate NameChangeRequests to DNS.
Francis Dupont's avatar
Francis Dupont committed
883
    // If we don't store the option in the response message, we will have to
884 885
    // propagate it in the different way to the functions which acquire the
    // lease. This would require modifications to the API of this class.
886
    ex.getResponse()->addOption(fqdn_resp);
887 888 889
}

void
890
Dhcpv4Srv::processHostnameOption(Dhcpv4Exchange& ex) {
891 892 893 894
    // Obtain the Hostname option from the client's message.
    OptionStringPtr opt_hostname = boost::dynamic_pointer_cast<OptionString>
        (ex.getQuery()->getOption(DHO_HOST_NAME));

895 896 897
    // Fetch D2 configuration.
    D2ClientMgr& d2_mgr = CfgMgr::instance().getD2ClientMgr();

898
    // Do nothing if the DNS updates are disabled.
899
    if (!d2_mgr.ddnsEnabled()) {
900 901 902
        return;
    }

903
    std::string hostname = isc::util::str::trim(opt_hostname->getValue());
904
    unsigned int label_count = OptionDataTypeUtil::getLabelCount(hostname);
905
    // The hostname option sent by the client should be at least 1 octet long.
906 907 908
    // If it isn't we ignore this option. (Per RFC 2131, section 3.14)
    /// @todo It would be more liberal to accept this and let it fall into
    /// the case  of replace or less than two below.
909 910 911 912
    if (label_count == 0) {
        LOG_DEBUG(dhcp4_logger, DBG_DHCP4_DETAIL_DATA, DHCP4_EMPTY_HOSTNAME);
        return;
    }
913 914 915 916
    // Copy construct the hostname provided by the client. It is entirely
    // possible that we will use the hostname option provided by the client
    // to perform the DNS update and we will send the same option to him to
    // indicate that we accepted this hostname.
917
    OptionStringPtr opt_hostname_resp(new OptionString(*opt_hostname));
918 919 920 921 922 923 924 925

    // The hostname option may be unqualified or fully qualified. The lab_count
    // holds the number of labels for the name. The number of 1 means that
    // there is only root label "." (even for unqualified names, as the
    // getLabelCount function treats each name as a fully qualified one).
    // By checking the number of labels present in the hostname we may infer
    // whether client has sent the fully qualified or unqualified hostname.

926
    // If there is a hostname reservation for this client, use it.
927
    if (ex.getContext()->host_ && !ex.getContext()->host_->getHostname().empty()) {
928 929
        opt_hostname_resp->setValue(d2_mgr.qualifyName(ex.getContext()->host_->getHostname(),
                                                       false));
930 931 932

    } else if ((d2_mgr.getD2ClientConfig()->getReplaceClientName()) ||
               (label_count < 2)) {
933 934
        // Set to root domain to signal later on that we should replace it.
        // DHO_HOST_NAME is a string option which cannot be empty.
935 936 937 938 939 940
        /// @todo We may want to reconsider whether it is appropriate for the
        /// client to send a root domain name as a Hostname. There are
        /// also extensions to the auto generation of the client's name,
        /// e.g. conversion to the puny code which may be considered at some point.
        /// For now, we just remain liberal and expect that the DNS will handle
        /// conversion if needed and possible.
941
        opt_hostname_resp->setValue(".");
942

943
    } else if (label_count == 2) {
944
        // If there are two labels, it means that the client has specified
Francis Dupont's avatar
Francis Dupont committed
945
        // the unqualified name. We have to concatenate the unqualified name
946 947 948 949 950 951
        // with the domain name. The false value passed as a second argument
        // indicates that the trailing dot should not be appended to the
        // hostname. We don't want to append the trailing dot because
        // we don't know whether the hostname is partial or not and some
        // clients do not handle the hostnames with the trailing dot.
        opt_hostname_resp->setValue(d2_mgr.qualifyName(hostname, false));
952 953
    }

954
    ex.getResponse()->addOption(opt_hostname_resp);
955 956
}

957 958
void
Dhcpv4Srv::createNameChangeRequests(const Lease4Ptr& lease,
959
                                    const Lease4Ptr& old_lease) {