dhcp.h

/*
 * Copyright (c) 2017, Matias Fontanini
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following disclaimer
 *   in the documentation and/or other materials provided with the
 *   distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef TINS_DHCP_H
#define TINS_DHCP_H

#include <vector>
#include <string>
#include <tins/bootp.h>
#include <tins/macros.h>
#include <tins/pdu_option.h>
#include <tins/cxxstd.h>

namespace Tins {

/** 
 * \class DHCP
 * \brief Represents the DHCP PDU.
 *
 * This class represents a DHCP PDU. It contains helpers methods
 * which make it easy to set/get specific option values.
 * 
 * Note that when adding options, the "End" option is not added 
 * automatically, so you will have to add it yourself.
 *
 * Options can be retrieved easily from DHCP PDUs:
 *
 * \code
 * // Sniff a packet from somewhere
 * DHCP dhcp = get_dhcp_from_somewhere();
 * 
 * // This retrieves the Domain Name Servers option and converts
 * // it to a std::vector<IPv4Address>. Note that if this option
 * // is not present, an option_not_found exception is thrown.
 * for(const auto& address : dhcp.domain_name_servers()) {
 *     // address is an ip
 * }
 * 
 * \endcode
 */
class TINS_API DHCP : public BootP {
public:
    /**
     * This PDU's flag.
     */
    static const PDU::PDUType pdu_flag = PDU::DHCP;

    /** 
     * DHCP flags.
     */
    enum Flags {
        DISCOVER = 1,
        OFFER    = 2,
        REQUEST	 = 3,
        DECLINE  = 4,
        ACK      = 5,
        NAK      = 6,
        RELEASE	 = 7,
        INFORM   = 8
    };
    
    /** 
     * \brief DHCP options enum.
     */
    enum OptionTypes {
        PAD,
        SUBNET_MASK,
        TIME_OFFSET,
        ROUTERS,
        TIME_SERVERS,
        NAME_SERVERS,
        DOMAIN_NAME_SERVERS,
        LOG_SERVERS,
        COOKIE_SERVERS,
        LPR_SERVERS,
        IMPRESS_SERVERS,
        RESOURCE_LOCATION_SERVERS,
        HOST_NAME,
        BOOT_SIZE,
        MERIT_DUMP,
        DOMAIN_NAME,
        SWAP_SERVER,
        ROOT_PATH,
        EXTENSIONS_PATH,
        IP_FORWARDING,
        NON_LOCAL_SOURCE_ROUTING,
        POLICY_FILTER,
        MAX_DGRAM_REASSEMBLY,
        DEFAULT_IP_TTL,
        PATH_MTU_AGING_TIMEOUT,
        PATH_MTU_PLATEAU_TABLE,
        INTERFACE_MTU,
        ALL_SUBNETS_LOCAL,
        BROADCAST_ADDRESS,
        PERFORM_MASK_DISCOVERY,
        MASK_SUPPLIER,
        ROUTER_DISCOVERY,
        ROUTER_SOLICITATION_ADDRESS,
        STATIC_ROUTES,
        TRAILER_ENCAPSULATION,
        ARP_CACHE_TIMEOUT,
        IEEE802_3_ENCAPSULATION,
        DEFAULT_TCP_TTL,
        TCP_KEEPALIVE_INTERVAL,
        TCP_KEEPALIVE_GARBAGE,
        NIS_DOMAIN,
        NIS_SERVERS,
        NTP_SERVERS,
        VENDOR_ENCAPSULATED_OPTIONS,
        NETBIOS_NAME_SERVERS,
        NETBIOS_DD_SERVER,
        NETBIOS_NODE_TYPE,
        NETBIOS_SCOPE,
        FONT_SERVERS,
        X_DISPLAY_MANAGER,
        DHCP_REQUESTED_ADDRESS,
        DHCP_LEASE_TIME,
        DHCP_OPTION_OVERLOAD,
        DHCP_MESSAGE_TYPE,
        DHCP_SERVER_IDENTIFIER,
        DHCP_PARAMETER_REQUEST_LIST,
        DHCP_MESSAGE,
        DHCP_MAX_MESSAGE_SIZE,
        DHCP_RENEWAL_TIME,
        DHCP_REBINDING_TIME,
        VENDOR_CLASS_IDENTIFIER,
        DHCP_CLIENT_IDENTIFIER,
        NWIP_DOMAIN_NAME,
        NWIP_SUBOPTIONS,
        USER_CLASS = 77,
        FQDN = 81,
        DHCP_AGENT_OPTIONS = 82,
        SUBNET_SELECTION = 118,
        AUTHENTICATE = 210,
        END	= 255
    };
    
    /**
     * The DHCP option type.
     */
    typedef PDUOption<uint8_t, DHCP> option;
    
    /**
     * The type used to store the DHCP options.
     */
    typedef std::vector<option> options_type;
    
    /**
     * \brief Extracts metadata for this protocol based on the buffer provided
     *
     * \param buffer Pointer to a buffer
     * \param total_sz Size of the buffer pointed by buffer
     */
    static metadata extract_metadata(const uint8_t *buffer, uint32_t total_sz);

    /** 
     * \brief Creates an instance of DHCP.
     * 
     * This sets the hwtype and hlen fields to match the ethernet
     * type and length.
     */
    DHCP();
    
    /**
     * \brief Constructs a DHCP object from a buffer.
     * 
     * If there is not enough size for a BootP header, or any of
     * the TLV options contains an invalid size field, then a
     * malformed_packet exception is thrown.
     * 
     * \param buffer The buffer from which this PDU will be constructed.
     * \param total_sz The total size of the buffer.
     */
    DHCP(const uint8_t* buffer, uint32_t total_sz);
    
    /** 
     * \brief Adds a new option to this DHCP PDU.
     * \param opt The option to be added.
     */
    void add_option(const option& opt);
    
    #if TINS_IS_CXX11
        /** 
         * \brief Adds a new option to this DHCP PDU.
         * 
         * The option is move-constructed.
         * 
         * \param opt The option to be added.
         */
        void add_option(option &&opt) {
            internal_add_option(opt);
            options_.push_back(std::move(opt));
        }
    #endif 

    /**
     * \brief Removes a DHCP option.
     * 
     * If there are multiple options of the given type, only the first one
     * will be removed.
     *
     * \param type The type of the option to be removed.
     * \return true if the option was removed, false otherwise.
     */
    bool remove_option(OptionTypes type);

    /**
     * \brief Searchs for an option that matchs the given flag.
     * \param opt_flag The flag to be searched.
     * \return A pointer to the option, or 0 if it was not found.
     */
    const option* search_option(OptionTypes opt) const;
    
    /** 
     * \brief Adds a type option to the option list.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param type The type of this DHCP PDU.
     */
    void type(Flags type);
    
    /** 
     * \brief Adds an end option to the option list.
     * 
     * The new option is appended at the end of the list.
     * 
     * The END option is not added automatically. You should explicitly
     * add it at the end of the DHCP options for the PDU to be
     * standard-compliant.
     */
    void end();
    
    /** 
     * \brief Adds a server identifier option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param ip The server's IP address.
     */
    void server_identifier(ipaddress_type ip);
    
    /** 
     * \brief Adds an IP address lease time option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param time The lease time.
     */
    void lease_time(uint32_t time);
    
    /** 
     * \brief Adds a lease renewal time option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param time The lease renew time.
     */
    void renewal_time(uint32_t time);
    
    /** 
     * \brief Adds a rebind time option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param time The lease rebind time.
     */
    void rebind_time(uint32_t time);
    
    /**
     * \brief Adds a subnet mask option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param mask The subnet mask.
     */
    void subnet_mask(ipaddress_type mask);
    
    /** 
     * \brief Adds a routers option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param routers A list of ip addresses.
     */
    void routers(const std::vector<ipaddress_type>& routers);
    
    /** 
     * \brief Adds a domain name servers option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param dns A list of ip addresses.
     */
    void domain_name_servers(const std::vector<ipaddress_type>& dns);
    
    /** 
     * \brief Adds a broadcast address option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param addr The broadcast address.
     */
    void broadcast(ipaddress_type addr);
    
    /** 
     * \brief Adds a requested address option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param addr The requested address.
     */
    void requested_ip(ipaddress_type addr);
    
    /** 
     * \brief Adds a domain name option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param name The domain name.
     */
    void domain_name(const std::string& name);

    /** 
     * \brief Adds a hostname option.
     * 
     * The new option is appended at the end of the list.
     * 
     * \param name The hostname.
     */
    void hostname(const std::string& name);
    
    // Option getters
    
    /**
     * \brief Searchs for a type option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return uint8_t containing the type option.
     */
    uint8_t type() const;
    
    /**
     * \brief Searchs for a server identifier option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return ipaddress_type Containing the server identifier.
     */
    ipaddress_type server_identifier() const;
    
    /**
     * \brief Searchs for a lease time option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return uint32_t Containing the lease time.
     */
    uint32_t lease_time() const;
            
    /**
     * \brief Searchs for a lease renewal time option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return uint32_t Containing the renewal time.
     */
    uint32_t renewal_time() const;
    
    /**
     * \brief Searchs for a rebind time option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return uint32_t Containing the rebind time.
     */
    uint32_t rebind_time() const;
    
    /**
     * \brief Searchs for a subnet mask option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return ipaddress_type Containing the subnet mask.
     */
    ipaddress_type subnet_mask() const;
    
    /**
     * \brief Searchs for a routers option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return std::vector<ipaddress_type> Containing the routers 
     * option data.
     */
    std::vector<ipaddress_type> routers() const;
    
    /**
     * \brief Searchs for a dns option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return The list of DNS servers provided.
     */
    std::vector<ipaddress_type> domain_name_servers() const; 
    
    /**
     * \brief Searchs for a broadcast option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return ipaddress_type Containing the broadcast address.
     */
    ipaddress_type broadcast() const;
    
    /**
     * \brief Searchs for a requested option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return ipaddress_type Containing the requested IP address.
     */
    ipaddress_type requested_ip() const;
    
    /**
     * \brief Searchs for a domain name option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return std::string Containing the domain name.
     */
    std::string domain_name() const;

    /**
     * \brief Searchs for a hostname option.
     * 
     * If the option is not found, an option_not_found exception
     * is thrown.
     * 
     * \return std::string Containing the hostname.
     */
    std::string hostname() const;
    
    /** 
     * \brief Getter for the options list.
     * \return The option list.
     */
    const options_type options() const { return options_; }
    
    /**
     * \brief Getter for the PDU's type.
     * \sa PDU::pdu_type
     */
    PDUType pdu_type() const { return pdu_flag; }
    
    /** 
     * \brief Getter for the header size.
     * \return Returns the BOOTP header size.
     * \sa PDU::header_size
     */ 
    uint32_t header_size() const;
    
    /**
     * \sa PDU::clone
     */
    DHCP* clone() const {
        return new DHCP(*this);
    }
private:
    static const uint32_t MAX_DHCP_SIZE;
  
    void write_serialization(uint8_t* buffer, uint32_t total_sz);

    template <typename T> 
    T search_and_convert(OptionTypes opt) const {
        const option* option = search_option(opt);
        if (!option) {
            throw option_not_found();
        }
        return option->to<T>();
    }
    
    void internal_add_option(const option& opt);
    serialization_type serialize_list(const std::vector<ipaddress_type>& ip_list);
    options_type::const_iterator search_option_iterator(OptionTypes opt) const;
    options_type::iterator search_option_iterator(OptionTypes opt);
    
    options_type options_;
    uint32_t size_;
};

} // Tins

#endif // TINS_DHCP_H