dhcp4_srv.h 33.2 KB
Newer Older
1
// Copyright (C) 2011-2016 Internet Systems Consortium, Inc. ("ISC")
2
//
3 4 5
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
6 7 8 9

#ifndef DHCPV4_SRV_H
#define DHCPV4_SRV_H

10
#include <dhcp/dhcp4.h>
11 12
#include <dhcp/pkt4.h>
#include <dhcp/option.h>
13
#include <dhcp/option_string.h>
14
#include <dhcp/option4_client_fqdn.h>
15
#include <dhcp/option_custom.h>
16
#include <dhcp_ddns/ncr_msg.h>
17
#include <dhcpsrv/d2_client_mgr.h>
18 19
#include <dhcpsrv/subnet.h>
#include <dhcpsrv/alloc_engine.h>
20
#include <dhcpsrv/cfg_option.h>
21
#include <hooks/callout_handle.h>
22
#include <dhcpsrv/daemon.h>
23 24 25

#include <boost/noncopyable.hpp>

26
#include <iostream>
27
#include <queue>
28

29 30 31 32
// Undefine the macro OPTIONAL which is defined in some operating
// systems but conflicts with a member of the RequirementLevel enum in
// the server class.

33 34 35 36
#ifdef OPTIONAL
#undef OPTIONAL
#endif

37 38
namespace isc {
namespace dhcp {
39

40 41 42 43 44
/// @brief DHCPv4 message exchange.
///
/// This class represents the DHCPv4 message exchange. The message exchange
/// consists of the single client message, server response to this message
/// and the mechanisms to generate the server's response. The server creates
45
/// the instance of the @c Dhcpv4Exchange for each inbound message that it
46 47
/// accepts for processing.
///
48
/// The use of the @c Dhcpv4Exchange object as a central repository of
49 50 51 52 53 54 55 56 57 58
/// information about the message exchange simplifies the API of the
/// @c Dhcpv4Srv class.
///
/// Another benefit of using this class is that different methods of the
/// @c Dhcpv4Srv may share information. For example, the constructor of this
/// class selects the subnet and multiple methods of @c Dhcpv4Srv use this
/// subnet, without the need to select it again.
///
/// @todo This is the initial version of this class. In the future a lot of
/// code from the @c Dhcpv4Srv class will be migrated here.
59
class Dhcpv4Exchange {
60 61 62 63 64 65 66 67 68 69 70 71
public:
    /// @brief Constructor.
    ///
    /// The constructor selects the subnet for the query and checks for the
    /// static host reservations for the client which has sent the message.
    /// The information about the reservations is stored in the
    /// @c AllocEngine::ClientContext4 object, which can be obtained by
    /// calling the @c getContext.
    ///
    /// @param alloc_engine Pointer to the instance of the Allocation Engine
    /// used by the server.
    /// @param query Pointer to the client message.
72 73 74
    /// @param subnet Pointer to the subnet to which the client belongs.
    Dhcpv4Exchange(const AllocEnginePtr& alloc_engine, const Pkt4Ptr& query,
                   const Subnet4Ptr& subnet);
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

    /// @brief Initializes the instance of the response message.
    ///
    /// The type of the response depends on the type of the query message.
    /// For the DHCPDISCOVER the DHCPOFFER is created. For the DHCPREQUEST
    /// and DHCPINFORM the DHCPACK is created. For the DHCPRELEASE the
    /// response is not initialized.
    void initResponse();

    /// @brief Returns the pointer to the query from the client.
    Pkt4Ptr getQuery() const {
        return (query_);
    }

    /// @brief Returns the pointer to the server's response.
    ///
    /// The returned pointer is NULL if the query type is DHCPRELEASE or DHCPDECLINE.
    Pkt4Ptr getResponse() const {
        return (resp_);
    }

    /// @brief Removes the response message by resetting the pointer to NULL.
    void deleteResponse() {
        resp_.reset();
    }

    /// @brief Returns the copy of the context for the Allocation engine.
    AllocEngine::ClientContext4Ptr getContext() const {
        return (context_);
    }

106
    /// @brief Returns the configured option list (non-const version)
107 108 109 110
    CfgOptionList& getCfgOptionList() {
        return (cfg_option_list_);
    }

111
    /// @brief Returns the configured option list (const version)
112 113 114 115
    const CfgOptionList& getCfgOptionList() const {
        return (cfg_option_list_);
    }

116
private:
117 118 119 120 121 122 123 124 125 126 127 128

    /// @brief Copies default parameters from client's to server's message
    ///
    /// Some fields are copied from client's message into server's response,
    /// e.g. client HW address, number of hops, transaction-id etc.
    ///
    /// @warning This message is called internally by @c initResponse and
    /// thus it doesn't check if the resp_ value has been initialized. The
    /// calling method is responsible for making sure that @c resp_ is
    /// not NULL.
    void copyDefaultFields();

129 130 131 132 133 134 135 136 137 138 139
    /// @brief Copies default options from client's to server's message
    ///
    /// Some options are copied from client's message into server's response,
    /// e.g. Relay Agent Info option, Subnet Selection option etc.
    ///
    /// @warning This message is called internally by @c initResponse and
    /// thus it doesn't check if the resp_ value has been initialized. The
    /// calling method is responsible for making sure that @c resp_ is
    /// not NULL.
    void copyDefaultOptions();

140 141
    /// @brief Set host identifiers within a context.
    ///
142
    /// This method sets an ordered list of host identifier types and
143
    /// values which the server should use to find host reservations.
144 145
    /// The order of the set is determined by the configuration parameter,
    /// host-reservation-identifiers
146 147
    void setHostIdentifiers();

148 149 150 151 152 153 154 155
    /// @brief Pointer to the allocation engine used by the server.
    AllocEnginePtr alloc_engine_;
    /// @brief Pointer to the DHCPv4 message sent by the client.
    Pkt4Ptr query_;
    /// @brief Pointer to the DHCPv4 message to be sent to the client.
    Pkt4Ptr resp_;
    /// @brief Context for use with allocation engine.
    AllocEngine::ClientContext4Ptr context_;
156 157 158
    /// @brief Configured option list.
    /// @note The configured option list is an *ordered* list of
    /// @c CfgOption objects used to append options to the response.
159
    CfgOptionList cfg_option_list_;
160 161
};

162 163
/// @brief Type representing the pointer to the @c Dhcpv4Exchange.
typedef boost::shared_ptr<Dhcpv4Exchange> Dhcpv4ExchangePtr;
164 165


166 167 168 169 170 171 172 173
/// @brief DHCPv4 server service.
///
/// This singleton class represents DHCPv4 server. It contains all
/// top-level methods and routines necessary for server operation.
/// In particular, it instantiates IfaceMgr, loads or generates DUID
/// that is going to be used as server-identifier, receives incoming
/// packets, processes them, manages leases assignment and generates
/// appropriate responses.
174 175
///
/// This class does not support any controlling mechanisms directly.
176
/// See the derived \ref ControlledDhcpv4Srv class for support for
177
/// command and configuration updates over msgq.
178
class Dhcpv4Srv : public Daemon {
179

180
public:
181 182 183 184 185 186 187 188

    /// @brief defines if certain option may, must or must not appear
    typedef enum {
        FORBIDDEN,
        MANDATORY,
        OPTIONAL
    } RequirementLevel;

189 190
    /// @brief Default constructor.
    ///
191
    /// Instantiates necessary services, required to run DHCPv4 server.
192 193
    /// In particular, creates IfaceMgr that will be responsible for
    /// network interaction. Will instantiate lease manager, and load
Tomek Mrugalski's avatar
Tomek Mrugalski committed
194 195
    /// old or create new DUID. It is possible to specify alternate
    /// port on which DHCPv4 server will listen on. That is mostly useful
196 197
    /// for testing purposes. The Last two arguments of the constructor
    /// should be left at default values for normal server operation.
Marcin Siodelski's avatar
Marcin Siodelski committed
198 199 200
    /// They should be set to 'false' when creating an instance of this
    /// class for unit testing because features they enable require
    /// root privileges.
Tomek Mrugalski's avatar
Tomek Mrugalski committed
201 202
    ///
    /// @param port specifies port number to listen on
203
    /// @param use_bcast configure sockets to support broadcast messages.
204 205
    /// @param direct_response_desired specifies if it is desired to
    /// use direct V4 traffic.
206
    Dhcpv4Srv(uint16_t port = DHCP4_SERVER_PORT,
207 208
              const bool use_bcast = true,
              const bool direct_response_desired = true);
209

210
    /// @brief Destructor. Used during DHCPv4 service shutdown.
211
    virtual ~Dhcpv4Srv();
212

213
    /// @brief returns Kea version on stdout and exit.
214
    /// redeclaration/redefinition. @ref Daemon::getVersion()
215 216
    static std::string getVersion(bool extended);
 
217 218
    /// @brief Main server processing loop.
    ///
Francis Dupont's avatar
Francis Dupont committed
219
    /// Main server processing loop. Call the processing step routine
Francis Dupont's avatar
Francis Dupont committed
220
    /// until shut down.
221
    ///
Francis Dupont's avatar
Francis Dupont committed
222
    /// @return true, if being shut down gracefully, never fail.
223 224
    bool run();

Francis Dupont's avatar
Francis Dupont committed
225
    /// @brief Main server processing step.
Francis Dupont's avatar
Francis Dupont committed
226
    ///
Francis Dupont's avatar
Francis Dupont committed
227
    /// Main server processing step. Receives one incoming packet, calls
228 229
    /// the processing packet routing and (if necessary) transmits
    /// a response.
Francis Dupont's avatar
Francis Dupont committed
230 231
    void run_one();

232 233 234
    /// @brief Process a single incoming DHCPv4 packet.
    ///
    /// It verifies correctness of the passed packet, call per-type processXXX
235
    /// methods, generates appropriate answer.
236 237
    ///
    /// @param query A pointer to the packet to be processed.
238 239
    /// @param rsp A pointer to the response
    void processPacket(Pkt4Ptr& query, Pkt4Ptr& rsp);
240

241
    /// @brief Instructs the server to shut down.
242 243
    void shutdown();

244 245 246 247 248 249 250
    ///
    /// @name Public accessors returning values required to (re)open sockets.
    ///
    //@{
    ///
    /// @brief Get UDP port on which server should listen.
    ///
251 252 253
    /// Typically, server listens on UDP port number 67. Other ports are used
    /// for testing purposes only.
    ///
254 255 256 257 258 259 260 261 262 263 264 265 266 267
    /// @return UDP port on which server should listen.
    uint16_t getPort() const {
        return (port_);
    }

    /// @brief Return bool value indicating that broadcast flags should be set
    /// on sockets.
    ///
    /// @return A bool value indicating that broadcast should be used (if true).
    bool useBroadcast() const {
        return (use_bcast_);
    }
    //@}

268 269
    /// @brief Starts DHCP_DDNS client IO if DDNS updates are enabled.
    ///
270
    /// If updates are enabled, it instructs the D2ClientMgr singleton to
271
    /// enter send mode.  If D2ClientMgr encounters errors it may throw
272
    /// D2ClientError. This method does not catch exceptions.
273 274
    void startD2();

275 276 277 278
    /// @brief Stops DHCP_DDNS client IO if DDNS updates are enabled.
    ///
    /// If updates are enabled, it instructs the D2ClientMgr singleton to
    /// leave send mode.  If D2ClientMgr encounters errors it may throw
279
    /// D2ClientError. This method does not catch exceptions.
280 281
    void stopD2();

282 283
    /// @brief Implements the error handler for DHCP_DDNS IO errors
    ///
284
    /// Invoked when a NameChangeRequest send to kea-dhcp-ddns completes with
285 286 287 288 289 290 291 292 293 294 295 296 297 298
    /// a failed status.  These are communications errors, not data related
    /// failures.
    ///
    /// This method logs the failure and then suspends all further updates.
    /// Updating can only be restored by reconfiguration or restarting the
    /// server.  There is currently no retry logic so the first IO error that
    /// occurs will suspend updates.
    /// @todo We may wish to make this more robust or sophisticated.
    ///
    /// @param result Result code of the send operation.
    /// @param ncr NameChangeRequest which failed to send.
    virtual void d2ClientErrorHandler(const dhcp_ddns::
                                      NameChangeSender::Result result,
                                      dhcp_ddns::NameChangeRequestPtr& ncr);
299
protected:
300

301 302 303 304 305 306 307
    /// @name Functions filtering and sanity-checking received messages.
    ///
    /// @todo These functions are supposed to be moved to a new class which
    /// will manage different rules for accepting and rejecting messages.
    /// Perhaps ticket #3116 is a good opportunity to do it.
    ///
    //@{
308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330
    /// @brief Checks whether received message should be processed or discarded.
    ///
    /// This function checks whether received message should be processed or
    /// discarded. It should be called on the beginning of message processing
    /// (just after the message has been decoded). This message calls a number
    /// of other functions which check whether message should be processed,
    /// using different criteria.
    ///
    /// This function should be extended when new criteria for accepting
    /// received message have to be implemented. This function is meant to
    /// aggregate all early filtering checks on the received message. By having
    /// a single function like this, we are avoiding bloat of the server's main
    /// loop.
    ///
    /// @warning This function should remain exception safe.
    ///
    /// @param query Received message.
    ///
    /// @return true if the message should be further processed, or false if
    /// the message should be discarded.
    bool accept(const Pkt4Ptr& query) const;

    /// @brief Check if a message sent by directly connected client should be
Francis Dupont's avatar
Francis Dupont committed
331
    /// accepted or discarded.
332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348
    ///
    /// This function checks if the received message is from directly connected
    /// client. If it is, it checks that it should be processed or discarded.
    ///
    /// Note that this function doesn't validate all addresses being carried in
    /// the message. The primary purpose of this function is to filter out
    /// direct messages in the local network for which there is no suitable
    /// subnet configured. For example, this function accepts unicast messages
    /// because unicasts may be used by clients located in remote networks to
    /// to renew existing leases. If their notion of address is wrong, the
    /// server will have to sent a NAK, instead of dropping the message.
    /// Detailed validation of such messages is performed at later stage of
    /// processing.
    ///
    /// This function accepts the following messages:
    /// - all valid relayed messages,
    /// - all unicast messages,
349 350 351
    /// - all broadcast messages except DHCPINFORM received on the interface
    /// for which the suitable subnet exists (is configured).
    /// - all DHCPINFORM messages with source address or ciaddr set.
352
    ///
353
    /// @param query Message sent by a client.
354 355 356
    ///
    /// @return true if message is accepted for further processing, false
    /// otherwise.
357 358 359 360 361
    bool acceptDirectRequest(const Pkt4Ptr& query) const;

    /// @brief Check if received message type is valid for the server to
    /// process.
    ///
Francis Dupont's avatar
Francis Dupont committed
362 363 364
    /// This function checks that the received message type belongs to
    /// the range of types recognized by the server and that the
    /// message of this type should be processed by the server.
365 366 367 368 369 370 371 372 373 374 375 376 377
    ///
    /// The messages types accepted for processing are:
    /// - Discover
    /// - Request
    /// - Release
    /// - Decline
    /// - Inform
    ///
    /// @param query Message sent by a client.
    ///
    /// @return true if message is accepted for further processing, false
    /// otherwise.
    bool acceptMessageType(const Pkt4Ptr& query) const;
378

379 380 381 382 383 384 385 386 387 388 389 390 391 392
    /// @brief Verifies if the server id belongs to our server.
    ///
    /// This function checks if the server identifier carried in the specified
    /// DHCPv4 message belongs to this server. If the server identifier option
    /// is absent or the value carried by this option is equal to one of the
    /// server identifiers used by the server, the true is returned. If the
    /// server identifier option is present, but it doesn't match any server
    /// identifier used by this server, the false value is returned.
    ///
    /// @param pkt DHCPv4 message which server identifier is to be checked.
    ///
    /// @return true, if the server identifier is absent or matches one of the
    /// server identifiers that the server is using; false otherwise.
    bool acceptServerId(const Pkt4Ptr& pkt) const;
393
    //@}
394

395
    /// @brief Verifies if specified packet meets RFC requirements
396 397 398 399
    ///
    /// Checks if mandatory option is really there, that forbidden option
    /// is not there, and that client-id or server-id appears only once.
    ///
400
    /// @param query Pointer to the client's message.
401 402
    /// @param serverid expectation regarding server-id option
    /// @throw RFCViolation if any issues are detected
403
    static void sanityCheck(const Pkt4Ptr& query, RequirementLevel serverid);
404

405 406 407 408 409 410
    /// @brief Processes incoming DISCOVER and returns response.
    ///
    /// Processes received DISCOVER message and verifies that its sender
    /// should be served. In particular, a lease is selected and sent
    /// as an offer to a client if it should be served.
    ///
411
    /// @param discover DISCOVER message received from client
412 413
    ///
    /// @return OFFER message or NULL
414
    Pkt4Ptr processDiscover(Pkt4Ptr& discover);
415 416 417 418 419

    /// @brief Processes incoming REQUEST and returns REPLY response.
    ///
    /// Processes incoming REQUEST message and verifies that its sender
    /// should be served. In particular, verifies that requested lease
Tomek Mrugalski's avatar
Tomek Mrugalski committed
420
    /// is valid, not expired, not reserved, not used by other client and
421 422
    /// that requesting client is allowed to use it.
    ///
423
    /// Returns ACK message, NAK message, or NULL
424 425 426
    ///
    /// @param request a message received from client
    ///
427
    /// @return ACK or NAK message
428
    Pkt4Ptr processRequest(Pkt4Ptr& request);
429

430
    /// @brief Processes incoming DHCPRELEASE messages.
431 432 433 434 435
    ///
    /// In DHCPv4, server does not respond to RELEASE messages, therefore
    /// this function does not return anything.
    ///
    /// @param release message received from client
436
    void processRelease(Pkt4Ptr& release);
437

Tomek Mrugalski's avatar
Tomek Mrugalski committed
438 439 440
    /// @brief Process incoming DHCPDECLINE messages.
    ///
    /// This method processes incoming DHCPDECLINE. In particular, it extracts
Shawn Routhier's avatar
Shawn Routhier committed
441
    /// Requested IP Address option, checks that the address really belongs to
Tomek Mrugalski's avatar
Tomek Mrugalski committed
442
    /// the client and if it does, calls @ref declineLease.
443 444
    ///
    /// @param decline message received from client
445
    void processDecline(Pkt4Ptr& decline);
446

447
    /// @brief Processes incoming DHCPINFORM messages.
448
    ///
449
    /// @param inform message received from client
450 451
    ///
    /// @return DHCPACK to be sent to the client.
452
    Pkt4Ptr processInform(Pkt4Ptr& inform);
453

454 455 456 457 458 459 460 461
    /// @brief Build the configured option list
    ///
    /// @note The configured option list is an *ordered* list of
    /// @c CfgOption objects used to append options to the response.
    ///
    /// @param ex The exchange where the configured option list is cached
    void buildCfgOptionList(Dhcpv4Exchange& ex);

Tomek Mrugalski's avatar
Tomek Mrugalski committed
462 463 464
    /// @brief Appends options requested by client.
    ///
    /// This method assigns options that were requested by client
Tomek Mrugalski's avatar
Tomek Mrugalski committed
465
    /// (sent in PRL) or are enforced by server.
Tomek Mrugalski's avatar
Tomek Mrugalski committed
466
    ///
467 468
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
469
    void appendRequestedOptions(Dhcpv4Exchange& ex);
Tomek Mrugalski's avatar
Tomek Mrugalski committed
470

471 472 473 474 475 476 477 478
    /// @brief Appends requested vendor options as requested by client.
    ///
    /// This method is similar to \ref appendRequestedOptions(), but uses
    /// vendor options. The major difference is that vendor-options use
    /// its own option spaces (there may be more than one distinct set of vendor
    /// options, each with unique vendor-id). Vendor options are requested
    /// using separate options within their respective vendor-option spaces.
    ///
479 480
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
481
    void appendRequestedVendorOptions(Dhcpv4Exchange& ex);
482

Tomek Mrugalski's avatar
Tomek Mrugalski committed
483 484
    /// @brief Assigns a lease and appends corresponding options
    ///
Francis Dupont's avatar
Francis Dupont committed
485
    /// This method chooses the most appropriate lease for requesting
Tomek Mrugalski's avatar
Tomek Mrugalski committed
486 487 488
    /// client and assigning it. Options corresponding to the lease
    /// are added to specific message.
    ///
489 490 491 492 493 494 495 496
    /// This method may reset the pointer to the response in the @c ex object
    /// to indicate that the response should not be sent to the client.
    /// The caller must check if the response is is null after calling
    /// this method.
    ///
    /// The response type in the @c ex object may be set to DHCPACK or DHCPNAK.
    ///
    /// @param ex DHCPv4 exchange holding the client's message to be checked.
497
    void assignLease(Dhcpv4Exchange& ex);
498

499 500 501
    /// @brief Append basic options if they are not present.
    ///
    /// This function adds the following basic options if they
502
    /// are not yet added to the response message:
503 504 505 506 507
    /// - Subnet Mask,
    /// - Router,
    /// - Name Server,
    /// - Domain Name.
    ///
508
    /// @param ex DHCPv4 exchange holding the client's message to be checked.
509
    void appendBasicOptions(Dhcpv4Exchange& ex);
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
    /// @brief Processes Client FQDN and Hostname Options sent by a client.
    ///
    /// Client may send Client FQDN or Hostname option to communicate its name
    /// to the server. Server may use this name to perform DNS update for the
    /// lease being assigned to a client. If server takes responsibility for
    /// updating DNS for a client it may communicate it by sending the Client
    /// FQDN or Hostname %Option back to the client. Server select a different
    /// name than requested by a client to update DNS. In such case, the server
    /// stores this different name in its response.
    ///
    /// Client should not send both Client FQDN and Hostname options. However,
    /// if client sends both options, server should prefer Client FQDN option
    /// and ignore the Hostname option. If Client FQDN option is not present,
    /// the Hostname option is processed.
    ///
    /// The Client FQDN %Option is processed by this function as described in
    /// RFC4702.
    ///
    /// In response to a Hostname %Option sent by a client, the server may send
    /// Hostname option with the same or different hostname. If different
    /// hostname is sent, it is an indication to the client that server has
    /// overridden the client's preferred name and will rather use this
    /// different name to update DNS. However, since Hostname option doesn't
    /// carry an information whether DNS update will be carried by the server
    /// or not, the client is responsible for checking whether DNS update
    /// has been performed.
    ///
    /// After successful processing options stored in the first parameter,
    /// this function may add Client FQDN or Hostname option to the response
    /// message. In some cases, server may cease to add any options to the
    /// response, i.e. when server doesn't support DNS updates.
    ///
543 544 545
    /// This function does not throw. It simply logs the debug message if the
    /// processing of the FQDN or Hostname failed.
    ///
546 547
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
548
    void processClientName(Dhcpv4Exchange& ex);
549

550 551 552 553 554 555 556 557
    /// @brief this is a prefix added to the contend of vendor-class option
    ///
    /// If incoming packet has a vendor class option, its content is
    /// prepended with this prefix and then interpreted as a class.
    /// For example, a packet that sends vendor class with value of "FOO"
    /// will cause the packet to be assigned to class VENDOR_CLASS_FOO.
    static const std::string VENDOR_CLASS_PREFIX;

558 559 560
private:
    /// @brief Process Client FQDN %Option sent by a client.
    ///
561 562 563 564 565 566
    /// This function is called by the @c Dhcpv4Srv::processClientName when
    /// the client has sent the FQDN option in its message to the server.
    /// It comprises the actual logic to parse the FQDN option and prepare
    /// the FQDN option to be sent back to the client in the server's
    /// response.
    ///
567 568
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
569
    void processClientFqdnOption(Dhcpv4Exchange& ex);
570 571 572

    /// @brief Process Hostname %Option sent by a client.
    ///
Francis Dupont's avatar
Francis Dupont committed
573
    /// This function is called by the @c Dhcpv4Srv::processClientName when
574 575 576 577 578
    /// the client has sent the Hostname option in its message to the server.
    /// It comprises the actual logic to parse the Hostname option and
    /// prepare the Hostname option to be sent back to the client in the
    /// server's response.
    ///
579 580
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
581
    void processHostnameOption(Dhcpv4Exchange& ex);
582

Francis Dupont's avatar
Francis Dupont committed
583
    /// @public
584 585 586 587 588 589 590
    /// @brief Marks lease as declined.
    ///
    /// This method moves a lease to declined state with all the steps involved:
    /// - trigger DNS removal (if necessary)
    /// - disassociate the client information
    /// - update lease in the database (switch to DECLINED state)
    /// - increase necessary statistics
591
    /// - call lease4_decline hook
592 593
    ///
    /// @param lease lease to be declined
594
    /// @param decline client's message
595
    void declineLease(const Lease4Ptr& lease, const Pkt4Ptr& decline);
596

597
protected:
598 599 600 601

    /// @brief Creates NameChangeRequests which correspond to the lease
    /// which has been acquired.
    ///
Francis Dupont's avatar
Francis Dupont committed
602
    /// If this function is called when an existing lease is renewed, it
603 604 605 606 607 608 609 610 611 612 613 614 615
    /// may generate NameChangeRequest to remove existing DNS entries which
    /// correspond to the old lease instance. This function may cease to
    /// generate NameChangeRequests if the notion of the client's FQDN hasn't
    /// changed between an old and new lease.
    ///
    /// @param lease A pointer to the new lease which has been acquired.
    /// @param old_lease A pointer to the instance of the old lease which has
    /// been replaced by the new lease passed in the first argument. The NULL
    /// value indicates that the new lease has been allocated, rather than
    /// lease being renewed.
    void createNameChangeRequests(const Lease4Ptr& lease,
                                  const Lease4Ptr& old_lease);

616 617 618 619 620
    /// @brief Attempts to renew received addresses
    ///
    /// Attempts to renew existing lease. This typically includes finding a lease that
    /// corresponds to the received address. If no such lease is found, a status code
    /// response is generated.
Tomek Mrugalski's avatar
Tomek Mrugalski committed
621
    ///
622 623 624
    /// @param renew client's message asking for renew
    /// @param reply server's response (ACK or NAK)
    void renewLease(const Pkt4Ptr& renew, Pkt4Ptr& reply);
Tomek Mrugalski's avatar
Tomek Mrugalski committed
625

626 627
    /// @brief Adds server identifier option to the server's response.
    ///
Francis Dupont's avatar
Francis Dupont committed
628
    /// This method adds a server identifier to the DHCPv4 message. It expects
629 630 631 632 633 634 635 636 637 638 639
    /// that the local (source) address is set for this message. If address is
    /// not set, it will throw an exception. This method also expects that the
    /// server identifier option is not present in the specified message.
    /// Otherwise, it will throw an exception on attempt to add a duplicate
    /// server identifier option.
    ///
    /// @note This method doesn't throw exceptions by itself but the underlying
    /// classes being used my throw. The reason for this method to not sanity
    /// check the specified message is that it is meant to be called internally
    /// by the @c Dhcpv4Srv class.
    ///
640 641 642
    /// @note This method is static because it is not dependent on the class
    /// state.
    ///
643 644
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
645
    static void appendServerID(Dhcpv4Exchange& ex);
646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662

    /// @brief Set IP/UDP and interface parameters for the DHCPv4 response.
    ///
    /// This method sets the following parameters for the DHCPv4 message being
    /// sent to a client:
    /// - client unicast or a broadcast address,
    /// - client or relay port,
    /// - server address,
    /// - server port,
    /// - name and index of the interface which is to be used to send the
    /// message.
    ///
    /// Internally it calls the @c Dhcpv4Srv::adjustRemoteAddr to figure
    /// out the destination address (client unicast address or broadcast
    /// address).
    ///
    /// The destination port is always DHCPv4 client (68) or relay (67) port,
663
    /// depending if the response will be sent directly to a client.
664 665 666 667 668 669 670 671 672 673
    ///
    /// The source port is always set to DHCPv4 server port (67).
    ///
    /// The interface selected for the response is always the same as the
    /// one through which the query has been received.
    ///
    /// The source address for the response is the IPv4 address assigned to
    /// the interface being used to send the response. This function uses
    /// @c IfaceMgr to get the socket bound to the IPv4 address on the
    /// particular interface.
674 675 676
    ///
    /// @note This method is static because it is not dependent on the class
    /// state.
677 678 679
    ///
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
680
    static void adjustIfaceData(Dhcpv4Exchange& ex);
681

682 683 684 685 686 687 688 689 690 691 692 693 694
    /// @brief Sets remote addresses for outgoing packet.
    ///
    /// This method sets the local and remote addresses on outgoing packet.
    /// The addresses being set depend on the following conditions:
    /// - has incoming packet been relayed,
    /// - is direct response to a client without address supported,
    /// - type of the outgoing packet,
    /// - broadcast flag set in the incoming packet.
    ///
    /// @warning This method does not check whether provided packet pointers
    /// are valid. Make sure that pointers are correct before calling this
    /// function.
    ///
695 696 697
    /// @note This method is static because it is not dependent on the class
    /// state.
    ///
698 699
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
700
    static void adjustRemoteAddr(Dhcpv4Exchange& ex);
701

702 703 704 705 706 707 708
    /// @brief converts server-id to text
    /// Converts content of server-id option to a text representation, e.g.
    /// "192.0.2.1"
    ///
    /// @param opt option that contains server-id
    /// @return string representation
    static std::string srvidToString(const OptionPtr& opt);
709

710 711
    /// @brief Selects a subnet for a given client's packet.
    ///
712
    /// @param query client's message
713
    /// @return selected subnet (or NULL if no suitable subnet was found)
714
    isc::dhcp::Subnet4Ptr selectSubnet(const Pkt4Ptr& query) const;
715

716 717
    /// indicates if shutdown is in progress. Setting it to true will
    /// initiate server shutdown procedure.
Tomek Mrugalski's avatar
Tomek Mrugalski committed
718
    volatile bool shutdown_;
719

720 721 722 723 724 725 726 727 728 729 730 731
    /// @brief dummy wrapper around IfaceMgr::receive4
    ///
    /// This method is useful for testing purposes, where its replacement
    /// simulates reception of a packet. For that purpose it is protected.
    virtual Pkt4Ptr receivePacket(int timeout);

    /// @brief dummy wrapper around IfaceMgr::send()
    ///
    /// This method is useful for testing purposes, where its replacement
    /// simulates transmission of a packet. For that purpose it is protected.
    virtual void sendPacket(const Pkt4Ptr& pkt);

732 733 734 735 736 737 738 739 740 741 742 743
    /// @brief Implements a callback function to parse options in the message.
    ///
    /// @param buf a A buffer holding options in on-wire format.
    /// @param option_space A name of the option space which holds definitions
    /// of to be used to parse options in the packets.
    /// @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 unpackOptions(const OptionBuffer& buf,
                         const std::string& option_space,
                         isc::dhcp::OptionCollection& options);

744 745
    /// @brief Assigns incoming packet to zero or more classes.
    ///
746
    /// @note This is done in two phases: first the content of the
747 748
    /// vendor-class-identifier option is used as a class, by
    /// calling @ref classifyByVendor(). Second classification match
749 750
    /// expressions are evaluated. The resulting classes will be stored
    /// in the packet (see @ref isc::dhcp::Pkt4::classes_ and
751
    /// @ref isc::dhcp::Pkt4::inClass).
752
    ///
753 754 755
    /// @param pkt packet to be classified
    void classifyPacket(const Pkt4Ptr& pkt);

756
    /// @brief Performs packet processing specific to a vendor class
757
    ///
758 759
    /// If the selected subnet, query or response in the @c ex object is NULL
    /// this method returns immediately and returns true.
760
    ///
761 762 763 764
    /// @note This processing is a likely candidate to be pushed into hooks.
    ///
    /// @param ex The exchange holding both the client's message and the
    /// server's response.
765
    /// @return true if successful, false otherwise (will prevent sending response)
766
    bool vendorClassSpecificProcessing(const Dhcpv4Exchange& ex);
767

768 769 770 771 772
    /// @brief Allocation Engine.
    /// Pointer to the allocation engine that we are currently using
    /// It must be a pointer, because we will support changing engines
    /// during normal operation (e.g. to use different allocators)
    boost::shared_ptr<AllocEngine> alloc_engine_;
773

774
private:
775

Francis Dupont's avatar
Francis Dupont committed
776
    /// @public
777 778 779 780 781 782 783 784
    /// @brief Assign class using vendor-class-identifier option
    ///
    /// @note This is the first part of @ref classifyPacket
    ///
    /// @param pkt packet to be classified
    /// @param classes a reference to added class names for logging
    void classifyByVendor(const Pkt4Ptr& pkt, std::string& classes);

Francis Dupont's avatar
Francis Dupont committed
785
    /// @private
786
    /// @brief Constructs netmask option based on subnet4
787
    /// @param subnet subnet for which the netmask will be calculated
788 789 790 791
    ///
    /// @return Option that contains netmask information
    static OptionPtr getNetmaskOption(const Subnet4Ptr& subnet);

792 793 794 795 796 797 798
    /// @brief Updates statistics for received packets
    /// @param query packet received
    static void processStatsReceived(const Pkt4Ptr& query);

    /// @brief Updates statistics for transmitted packets
    /// @param query packet transmitted
    static void processStatsSent(const Pkt4Ptr& response);
799

800 801 802
    uint16_t port_;  ///< UDP port number on which server listens.
    bool use_bcast_; ///< Should broadcast be enabled on sockets (if true).

803 804 805 806
    /// Indexes for registered hook points
    int hook_index_pkt4_receive_;
    int hook_index_subnet4_select_;
    int hook_index_pkt4_send_;
807 808 809 810 811 812
};

}; // namespace isc::dhcp
}; // namespace isc

#endif // DHCP4_SRV_H