dhcp.h

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#ifndef _IPXE_DHCP_H
#define _IPXE_DHCP_H
 
/** @file
 *
 * Dynamic Host Configuration Protocol
 *
 */
 
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );
 
#include <stdint.h>
#include <stdarg.h>
#include <ipxe/in.h>
#include <ipxe/list.h>
#include <ipxe/refcnt.h>
#include <ipxe/tables.h>
#include <ipxe/uuid.h>
#include <ipxe/netdevice.h>
 
struct interface;
struct dhcp_options;
struct dhcp_packet;
 
/** BOOTP/DHCP server port */
#define BOOTPS_PORT 67
 
/** BOOTP/DHCP client port */
#define BOOTPC_PORT 68
 
/** PXE server port */
#define PXE_PORT 4011
 
/** Construct a tag value for an encapsulated option
 *
 * This tag value can be passed to Etherboot functions when searching
 * for DHCP options in order to search for a tag within an
 * encapsulated options block.
 */
#define DHCP_ENCAP_OPT( encapsulator, encapsulated ) \
        ( ( (encapsulator) << 8 ) | (encapsulated) )
/** Extract encapsulating option block tag from encapsulated tag value */
#define DHCP_ENCAPSULATOR( encap_opt ) ( (encap_opt) >> 8 )
/** Extract encapsulated option tag from encapsulated tag value */
#define DHCP_ENCAPSULATED( encap_opt ) ( (encap_opt) & 0xff )
/** Option is encapsulated */
#define DHCP_IS_ENCAP_OPT( opt ) DHCP_ENCAPSULATOR( opt )
 
/**
 * @defgroup dhcpopts DHCP option tags
 * @{
 */
 
/** Padding
 *
 * This tag does not have a length field; it is always only a single
 * byte in length.
 */
#define DHCP_PAD 0
 
/** Minimum normal DHCP option */
#define DHCP_MIN_OPTION 1
 
/** Subnet mask */
#define DHCP_SUBNET_MASK 1
 
/** Routers */
#define DHCP_ROUTERS 3
 
/** DNS servers */
#define DHCP_DNS_SERVERS 6
 
/** Syslog servers */
#define DHCP_LOG_SERVERS 7
 
/** Host name */
#define DHCP_HOST_NAME 12
 
/** Domain name */
#define DHCP_DOMAIN_NAME 15
 
/** Root path */
#define DHCP_ROOT_PATH 17
 
/** Maximum transmission unit */
#define DHCP_MTU 26
 
/** NTP servers */
#define DHCP_NTP_SERVERS 42
 
/** Vendor encapsulated options */
#define DHCP_VENDOR_ENCAP 43
 
/** PXE boot server discovery control */
#define DHCP_PXE_DISCOVERY_CONTROL DHCP_ENCAP_OPT ( DHCP_VENDOR_ENCAP, 6 )
 
/** PXE boot server discovery control bits */
enum dhcp_pxe_discovery_control {
        /** Inhibit broadcast discovery */
        PXEBS_NO_BROADCAST = 1,
        /** Inhibit multicast discovery */
        PXEBS_NO_MULTICAST = 2,
        /** Accept only servers in DHCP_PXE_BOOT_SERVERS list */
        PXEBS_NO_UNKNOWN_SERVERS = 4,
        /** Skip discovery if filename present */
        PXEBS_SKIP = 8,
};
 
/** PXE boot server multicast address */
#define DHCP_PXE_BOOT_SERVER_MCAST DHCP_ENCAP_OPT ( DHCP_VENDOR_ENCAP, 7 )
 
/** PXE boot servers */
#define DHCP_PXE_BOOT_SERVERS DHCP_ENCAP_OPT ( DHCP_VENDOR_ENCAP, 8 )
 
/** PXE boot server */
struct dhcp_pxe_boot_server {
        /** "Type" */
        uint16_t type;
        /** Number of IPv4 addresses */
        uint8_t num_ip;
        /** IPv4 addresses */
        struct in_addr ip[0];
} __attribute__ (( packed ));
 
/** PXE boot menu */
#define DHCP_PXE_BOOT_MENU DHCP_ENCAP_OPT ( DHCP_VENDOR_ENCAP, 9 )
 
/** PXE boot menu */
struct dhcp_pxe_boot_menu {
        /** "Type" */
        uint16_t type;
        /** Description length */
        uint8_t desc_len;
        /** Description */
        char desc[0];
} __attribute__ (( packed ));
 
/** PXE boot menu prompt */
#define DHCP_PXE_BOOT_MENU_PROMPT DHCP_ENCAP_OPT ( DHCP_VENDOR_ENCAP, 10 )
 
/** PXE boot menu prompt */
struct dhcp_pxe_boot_menu_prompt {
        /** Timeout
         *
         * A value of 0 means "time out immediately and select first
         * boot item, without displaying the prompt".  A value of 255
         * means "display menu immediately with no timeout".  Any
         * other value means "display prompt, wait this many seconds
         * for keypress, if key is F8, display menu, otherwise select
         * first boot item".
         */
        uint8_t timeout;
        /** Prompt to press F8 */
        char prompt[0];
} __attribute__ (( packed ));
 
/** PXE boot menu item */
#define DHCP_PXE_BOOT_MENU_ITEM DHCP_ENCAP_OPT ( DHCP_VENDOR_ENCAP, 71 )
 
/** PXE boot menu item */
struct dhcp_pxe_boot_menu_item {
        /** "Type"
         *
         * This field actually identifies the specific boot server (or
         * cluster of boot servers offering identical boot files).
         */
        uint16_t type;
        /** "Layer"
         *
         * Just don't ask.
         */
        uint16_t layer;
} __attribute__ (( packed ));
 
/** Requested IP address */
#define DHCP_REQUESTED_ADDRESS 50
 
/** Lease time */
#define DHCP_LEASE_TIME 51
 
/** Option overloading
 *
 * The value of this option is the bitwise-OR of zero or more
 * DHCP_OPTION_OVERLOAD_XXX constants.
 */
#define DHCP_OPTION_OVERLOAD 52
 
/** The "file" field is overloaded to contain extra DHCP options */
#define DHCP_OPTION_OVERLOAD_FILE 1
 
/** The "sname" field is overloaded to contain extra DHCP options */
#define DHCP_OPTION_OVERLOAD_SNAME 2
 
/** DHCP message type */
#define DHCP_MESSAGE_TYPE 53
#define DHCPNONE 0
#define DHCPDISCOVER 1
#define DHCPOFFER 2
#define DHCPREQUEST 3
#define DHCPDECLINE 4
#define DHCPACK 5
#define DHCPNAK 6
#define DHCPRELEASE 7
#define DHCPINFORM 8
 
/** DHCP server identifier */
#define DHCP_SERVER_IDENTIFIER 54
 
/** Parameter request list */
#define DHCP_PARAMETER_REQUEST_LIST 55
 
/** Maximum DHCP message size */
#define DHCP_MAX_MESSAGE_SIZE 57
 
/** Vendor class identifier */
#define DHCP_VENDOR_CLASS_ID 60
 
/** Vendor class identifier for PXE clients */
#define DHCP_VENDOR_PXECLIENT( arch, ndi )                              \
        'P', 'X', 'E', 'C', 'l', 'i', 'e', 'n', 't', ':',               \
        'A', 'r', 'c', 'h', ':', DHCP_VENDOR_PXECLIENT_ARCH ( arch ),   \
        ':', 'U', 'N', 'D', 'I', ':', DHCP_VENDOR_PXECLIENT_UNDI ( ndi )
 
/** Vendor class identifier architecture for PXE clients */
#define DHCP_VENDOR_PXECLIENT_ARCH( arch )                              \
        ( '0' + ( ( (arch) / 10000 ) % 10 ) ),                          \
        ( '0' + ( ( (arch) /  1000 ) % 10 ) ),                          \
        ( '0' + ( ( (arch) /   100 ) % 10 ) ),                          \
        ( '0' + ( ( (arch) /    10 ) % 10 ) ),                          \
        ( '0' + ( ( (arch) /     1 ) % 10 ) )
 
/** Vendor class identifier UNDI version for PXE clients */
#define DHCP_VENDOR_PXECLIENT_UNDI( type, major, minor )                \
        DHCP_VENDOR_PXECLIENT_UNDI_VERSION ( major ),                   \
        DHCP_VENDOR_PXECLIENT_UNDI_VERSION ( minor )
#define DHCP_VENDOR_PXECLIENT_UNDI_VERSION( version )                   \
        ( '0' + ( ( (version) /   100 ) % 10 ) ),                       \
        ( '0' + ( ( (version) /    10 ) % 10 ) ),                       \
        ( '0' + ( ( (version) /     1 ) % 10 ) )
 
/** Client identifier */
#define DHCP_CLIENT_ID 61
 
/** Client identifier */
struct dhcp_client_id {
        /** Link-layer protocol */
        uint8_t ll_proto;
        /** Link-layer address */
        uint8_t ll_addr[MAX_LL_ADDR_LEN];
} __attribute__ (( packed ));
 
/** TFTP server name
 *
 * This option replaces the fixed "sname" field, when that field is
 * used to contain overloaded options.
 */
#define DHCP_TFTP_SERVER_NAME 66
 
/** Bootfile name
 *
 * This option replaces the fixed "file" field, when that field is
 * used to contain overloaded options.
 */
#define DHCP_BOOTFILE_NAME 67
 
/** User class identifier */
#define DHCP_USER_CLASS_ID 77
 
/** Client system architecture */
#define DHCP_CLIENT_ARCHITECTURE 93
 
/** DHCP client architecture */
struct dhcp_client_architecture {
        uint16_t arch;
} __attribute__ (( packed ));
 
/** DHCP client architecture values
 *
 * These are originally defined by the PXE specification, redefined by
 * RFC4578, redefined again by RFC5970, and now maintained in the IANA
 * DHCPv6 parameters registry.
 */
enum dhcp_client_architecture_values {
        /** Intel x86 PC */
        DHCP_CLIENT_ARCHITECTURE_X86 = 0x0000,
        /** NEC/PC98 */
        DHCP_CLIENT_ARCHITECTURE_PC98 = 0x0001,
        /** EFI Itanium */
        DHCP_CLIENT_ARCHITECTURE_IA64 = 0x0002,
        /** DEC Alpha */
        DHCP_CLIENT_ARCHITECTURE_ALPHA = 0x0003,
        /** Arc x86 */
        DHCP_CLIENT_ARCHITECTURE_ARCX86 = 0x0004,
        /** Intel Lean Client */
        DHCP_CLIENT_ARCHITECTURE_LC = 0x0005,
        /** EFI IA32 */
        DHCP_CLIENT_ARCHITECTURE_IA32 = 0x0006,
        /** EFI x86-64 */
        DHCP_CLIENT_ARCHITECTURE_X86_64 = 0x0007,
        /** EFI Xscale */
        DHCP_CLIENT_ARCHITECTURE_XSCALE = 0x0008,
        /** EFI BC */
        DHCP_CLIENT_ARCHITECTURE_EFI = 0x0009,
        /** EFI 32-bit ARM */
        DHCP_CLIENT_ARCHITECTURE_ARM32 = 0x000a,
        /** EFI 64-bit ARM */
        DHCP_CLIENT_ARCHITECTURE_ARM64 = 0x000b,
        /** EFI 32-bit RISC-V */
        DHCP_CLIENT_ARCHITECTURE_RISCV32 = 0x0019,
        /** EFI 64-bit RISC-V */
        DHCP_CLIENT_ARCHITECTURE_RISCV64 = 0x001b,
        /** EFI 128-bit RISC-V */
        DHCP_CLIENT_ARCHITECTURE_RISCV128 = 0x001d,
        /** EFI 32-bit MIPS */
        DHCP_CLIENT_ARCHITECTURE_MIPS32 = 0x0021,
        /** EFI 64-bit MIPS */
        DHCP_CLIENT_ARCHITECTURE_MIPS64 = 0x0022,
        /** EFI 32-bit Sunway */
        DHCP_CLIENT_ARCHITECTURE_SUNWAY32 = 0x0023,
        /** EFI 64-bit Sunway */
        DHCP_CLIENT_ARCHITECTURE_SUNWAY64 = 0x0024,
        /** EFI 32-bit LoongArch */
        DHCP_CLIENT_ARCHITECTURE_LOONG32 = 0x0025,
        /** EFI 64-bit LoongArch */
        DHCP_CLIENT_ARCHITECTURE_LOONG64 = 0x0027,
};
 
/** Client network device interface */
#define DHCP_CLIENT_NDI 94
 
/** UUID client identifier */
#define DHCP_CLIENT_UUID 97
 
/** UUID client identifier */
struct dhcp_client_uuid {
        /** Identifier type */
        uint8_t type;
        /** UUID */
        union uuid uuid;
} __attribute__ (( packed ));
 
#define DHCP_CLIENT_UUID_TYPE 0
 
/** DNS domain search list */
#define DHCP_DOMAIN_SEARCH 119
 
/** Classless static routes */
#define DHCP_STATIC_ROUTES 121
 
/** Etherboot-specific encapsulated options
 *
 * This encapsulated options field is used to contain all options
 * specific to Etherboot (i.e. not assigned by IANA or other standards
 * bodies).
 */
#define DHCP_EB_ENCAP 175
 
/** Priority of this options block
 *
 * This is a signed 8-bit integer field indicating the priority of
 * this block of options.  It can be used to specify the relative
 * priority of multiple option blocks (e.g. options from non-volatile
 * storage versus options from a DHCP server).
 */
#define DHCP_EB_PRIORITY DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x01 )
 
/** "Your" IP address
 *
 * This option is used internally to contain the value of the "yiaddr"
 * field, in order to provide a consistent approach to storing and
 * processing options.  It should never be present in a DHCP packet.
 */
#define DHCP_EB_YIADDR DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x02 )
 
/** "Server" IP address
 *
 * This option is used internally to contain the value of the "siaddr"
 * field, in order to provide a consistent approach to storing and
 * processing options.  It should never be present in a DHCP packet.
 */
#define DHCP_EB_SIADDR DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x03 )
 
/** Keep SAN drive registered
 *
 * If set to a non-zero value, iPXE will not detach any SAN drive
 * after failing to boot from it.  (This option is required in order
 * to perform an installation direct to an iSCSI target.)
 */
#define DHCP_EB_KEEP_SAN DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x08 )
 
/** Skip booting from SAN drive
 *
 * If set to a non-zero value, iPXE will skip booting from any SAN
 * drive.  (This option is sometimes required in conjunction with @c
 * DHCP_EB_KEEP_SAN in order to perform an installation direct to an
 * iSCSI target.)
 */
#define DHCP_EB_SKIP_SAN_BOOT DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x09 )
 
/*
 * Tags in the range 0x10-0x4f are reserved for feature markers
 *
 */
 
/** Scriptlet
 *
 * If a scriptlet exists, it will be executed in place of the usual
 * call to autoboot()
 */
#define DHCP_EB_SCRIPTLET DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x51 )
 
/** Encrypted syslog server */
#define DHCP_EB_SYSLOGS_SERVER DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x55 )
 
/** Trusted root certficate fingerprints */
#define DHCP_EB_TRUST DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x5a )
 
/** Client certficate */
#define DHCP_EB_CERT DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x5b )
 
/** Client private key */
#define DHCP_EB_KEY DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x5c )
 
/** Cross-signed certificate source */
#define DHCP_EB_CROSS_CERT DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x5d )
 
/** Skip PXE DHCP protocol extensions such as ProxyDHCP
 *
 * If set to a non-zero value, iPXE will not wait for ProxyDHCP offers
 * and will ignore any PXE-specific DHCP options that it receives.
 */
#define DHCP_EB_NO_PXEDHCP DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xb0 )
 
/** Network device descriptor
 *
 * Byte 0 is the bus type ID; remaining bytes depend on the bus type.
 *
 * PCI devices:
 * Byte 0 : 1 (PCI)
 * Byte 1 : PCI vendor ID MSB
 * Byte 2 : PCI vendor ID LSB
 * Byte 3 : PCI device ID MSB
 * Byte 4 : PCI device ID LSB
 */
#define DHCP_EB_BUS_ID DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xb1 )
 
/** Network device descriptor */
struct dhcp_netdev_desc {
        /** Bus type ID */
        uint8_t type;
        /** Vendor ID */
        uint16_t vendor;
        /** Device ID */
        uint16_t device;
} __attribute__ (( packed ));
 
/** Use cached network settings (obsolete; do not reuse this value) */
#define DHCP_EB_USE_CACHED DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xb2 )
 
/** SAN retry count
 *
 * This is the maximum number of times that SAN operations will be
 * retried.
 */
#define DHCP_EB_SAN_RETRY DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbb )
 
/** SAN filename
 *
 * This is the path of the bootloader within the SAN device.
 */
#define DHCP_EB_SAN_FILENAME DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbc )
 
/** SAN drive number
 *
 * This is the drive number for a SAN-hooked drive.  For BIOS, 0x80 is
 * the first hard disk, 0x81 is the second hard disk, etc.
 */
#define DHCP_EB_SAN_DRIVE DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbd )
 
/** Username
 *
 * This will be used as the username for any required authentication.
 * It is expected that this option's value will be held in
 * non-volatile storage, rather than transmitted as part of a DHCP
 * packet.
 */
#define DHCP_EB_USERNAME DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbe )
 
/** Password
 *
 * This will be used as the password for any required authentication.
 * It is expected that this option's value will be held in
 * non-volatile storage, rather than transmitted as part of a DHCP
 * packet.
 */
#define DHCP_EB_PASSWORD DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbf )
 
/** Reverse username
 *
 * This will be used as the reverse username (i.e. the username
 * provided by the server) for any required authentication.  It is
 * expected that this option's value will be held in non-volatile
 * storage, rather than transmitted as part of a DHCP packet.
 */
#define DHCP_EB_REVERSE_USERNAME DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xc0 )
 
/** Reverse password
 *
 * This will be used as the reverse password (i.e. the password
 * provided by the server) for any required authentication.  It is
 * expected that this option's value will be held in non-volatile
 * storage, rather than transmitted as part of a DHCP packet.
 */
#define DHCP_EB_REVERSE_PASSWORD DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xc1 )
 
/** User ID
 *
 * This will be used as the user id for AUTH_SYS based authentication in NFS.
 */
#define DHCP_EB_UID DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xc2 )
 
/** Group ID
 *
 * This will be used as the group id for AUTH_SYS based authentication in NFS.
 */
#define DHCP_EB_GID DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xc3 )
 
/** iPXE version number */
#define DHCP_EB_VERSION DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xeb )
 
/** iSCSI primary target IQN */
#define DHCP_ISCSI_PRIMARY_TARGET_IQN 201
 
/** iSCSI secondary target IQN */
#define DHCP_ISCSI_SECONDARY_TARGET_IQN 202
 
/** iSCSI initiator IQN */
#define DHCP_ISCSI_INITIATOR_IQN 203
 
/** Maximum normal DHCP option */
#define DHCP_MAX_OPTION 254
 
/** End of options
 *
 * This tag does not have a length field; it is always only a single
 * byte in length.
 */
#define DHCP_END 255
 
/** @} */
 
/** Construct a DHCP option from a list of bytes */
#define DHCP_OPTION( ... ) VA_ARG_COUNT ( __VA_ARGS__ ), __VA_ARGS__
 
/** Construct a DHCP option from a list of characters */
#define DHCP_STRING( ... ) DHCP_OPTION ( __VA_ARGS__ )
 
/** Construct a byte-valued DHCP option */
#define DHCP_BYTE( value ) DHCP_OPTION ( value )
 
/** Construct a word-valued DHCP option */
#define DHCP_WORD( value ) DHCP_OPTION ( ( ( (value) >> 8 ) & 0xff ),   \
                                         ( ( (value) >> 0 ) & 0xff ) )
 
/** Construct a dword-valued DHCP option */
#define DHCP_DWORD( value ) DHCP_OPTION ( ( ( (value) >> 24 ) & 0xff ), \
                                          ( ( (value) >> 16 ) & 0xff ), \
                                          ( ( (value) >> 8  ) & 0xff ), \
                                          ( ( (value) >> 0  ) & 0xff ) )
 
/** Construct a DHCP encapsulated options field */
#define DHCP_ENCAP( ... ) DHCP_OPTION ( __VA_ARGS__, DHCP_END )
 
/**
 * A DHCP option
 *
 * DHCP options consist of a mandatory tag, a length field that is
 * mandatory for all options except @c DHCP_PAD and @c DHCP_END, and a
 * payload.  
 */
struct dhcp_option {
        /** Tag
         *
         * Must be a @c DHCP_XXX value.
         */
        uint8_t tag;
        /** Length
         *
         * This is the length of the data field (i.e. excluding the
         * tag and length fields).  For the two tags @c DHCP_PAD and
         * @c DHCP_END, the length field is implicitly zero and is
         * also missing, i.e. these DHCP options are only a single
         * byte in length.
         */
        uint8_t len;
        /** Option data */
        uint8_t data[0];
} __attribute__ (( packed ));
 
/**
 * Length of a DHCP option header
 *
 * The header is the portion excluding the data, i.e. the tag and the
 * length.
 */
#define DHCP_OPTION_HEADER_LEN ( offsetof ( struct dhcp_option, data ) )
 
/** Maximum length for a single DHCP option */
#define DHCP_MAX_LEN 0xff
 
/**
 * A DHCP header
 *
 */
struct dhcphdr {
        /** Operation
         *
         * This must be either @c BOOTP_REQUEST or @c BOOTP_REPLY.
         */
        uint8_t op;
        /** Hardware address type
         *
         * This is an ARPHRD_XXX constant.  Note that ARPHRD_XXX
         * constants are nominally 16 bits wide; this could be
         * considered to be a bug in the BOOTP/DHCP specification.
         */
        uint8_t htype;
        /** Hardware address length */
        uint8_t hlen;
        /** Number of hops from server */
        uint8_t hops;
        /** Transaction ID */
        uint32_t xid;
        /** Seconds since start of acquisition */
        uint16_t secs;
        /** Flags */
        uint16_t flags;
        /** "Client" IP address
         *
         * This is filled in if the client already has an IP address
         * assigned and can respond to ARP requests.
         */
        struct in_addr ciaddr;
        /** "Your" IP address
         *
         * This is the IP address assigned by the server to the client.
         */
        struct in_addr yiaddr;
        /** "Server" IP address
         *
         * This is the IP address of the next server to be used in the
         * boot process.
         */
        struct in_addr siaddr;
        /** "Gateway" IP address
         *
         * This is the IP address of the DHCP relay agent, if any.
         */
        struct in_addr giaddr;
        /** Client hardware address */
        uint8_t chaddr[16];
        /** Server host name (null terminated)
         *
         * This field may be overridden and contain DHCP options
         */
        char sname[64];
        /** Boot file name (null terminated)
         *
         * This field may be overridden and contain DHCP options
         */
        char file[128];
        /** DHCP magic cookie
         *
         * Must have the value @c DHCP_MAGIC_COOKIE.
         */
        uint32_t magic;
        /** DHCP options
         *
         * Variable length; extends to the end of the packet.  Minimum
         * length (for the sake of sanity) is 1, to allow for a single
         * @c DHCP_END tag.
         */
        uint8_t options[0];
};
 
/** Opcode for a request from client to server */
#define BOOTP_REQUEST 1
 
/** Opcode for a reply from server to client */
#define BOOTP_REPLY 2
 
/** BOOTP reply must be broadcast
 *
 * Clients that cannot accept unicast BOOTP replies must set this
 * flag.
 */
#define BOOTP_FL_BROADCAST 0x8000
 
/** DHCP magic cookie */
#define DHCP_MAGIC_COOKIE 0x63825363UL
 
/** DHCP minimum packet length
 *
 * This is the mandated minimum packet length that a DHCP participant
 * must be prepared to receive.
 */
#define DHCP_MIN_LEN 552
 
/** Settings block name used for DHCP responses */
#define DHCP_SETTINGS_NAME "dhcp"
 
/** Settings block name used for ProxyDHCP responses */
#define PROXYDHCP_SETTINGS_NAME "proxydhcp"
 
/** Setting block name used for BootServerDHCP responses */
#define PXEBS_SETTINGS_NAME "pxebs"
 
extern uint32_t dhcp_last_xid;
extern int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
                                struct net_device *netdev, uint8_t msgtype,
                                uint32_t xid, const void *options,
                                size_t options_len, void *data,
                                size_t max_len );
extern int dhcp_create_request ( struct dhcp_packet *dhcppkt,
                                 struct net_device *netdev,
                                 unsigned int msgtype, uint32_t xid,
                                 struct in_addr ciaddr,
                                 void *data, size_t max_len );
extern int start_dhcp ( struct interface *job, struct net_device *netdev );
extern int start_pxebs ( struct interface *job, struct net_device *netdev,
                         unsigned int pxe_type );
 
#endif /* _IPXE_DHCP_H */