dhcp.h

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#ifndef _GPXE_DHCP_H
#define _GPXE_DHCP_H

/** @file
 *
 * Dynamic Host Configuration Protocol
 *
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>
#include <gpxe/in.h>
#include <gpxe/list.h>
#include <gpxe/refcnt.h>
#include <gpxe/tables.h>
#include <gpxe/uuid.h>
#include <gpxe/netdevice.h>
#include <gpxe/uaccess.h>

struct job_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

/** 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

/** 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

/** 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

/** 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, gPXE will not detach any SAN drive
 * after failing to boot from it.  (This option is required in order
 * to perform a Windows Server 2008 installation direct to an iSCSI
 * target.)
 */
#define DHCP_EB_KEEP_SAN DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0x08 )

/*
 * Tags in the range 0x10-0x7f are reserved for feature markers
 *
 */

/** Skip PXE DHCP protocol extensions such as ProxyDHCP
 *
 * If set to a non-zero value, gPXE 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
 *
 * Cached network settings may be available from a prior DHCP request
 * (if running as a PXE NBP), non-volatile storage on the NIC, or
 * settings set via the command line or an embedded image. If this
 * flag is not set, it will be assumed that those sources are
 * insufficient and that DHCP should still be run when autobooting.
 */
#define DHCP_EB_USE_CACHED DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xb2 )

/** BIOS drive number
 *
 * This is the drive number for a drive emulated via INT 13.  0x80 is
 * the first hard disk, 0x81 is the second hard disk, etc.
 */
#define DHCP_EB_BIOS_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 )

/** gPXE 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

/** @} */

/**
 * Count number of arguments to a variadic macro
 *
 * This rather neat, non-iterative solution is courtesy of Laurent
 * Deniau.
 *
 */
#define _VA_ARG_COUNT(  _1,  _2,  _3,  _4,  _5,  _6,  _7,  _8,          \
                        _9, _10, _11, _12, _13, _14, _15, _16,          \
                       _17, _18, _19, _20, _21, _22, _23, _24,          \
                       _25, _26, _27, _28, _29, _30, _31, _32,          \
                       _33, _34, _35, _36, _37, _38, _39, _40,          \
                       _41, _42, _43, _44, _45, _46, _47, _48,          \
                       _49, _50, _51, _52, _53, _54, _55, _56,          \
                       _57, _58, _59, _60, _61, _62, _63,   N, ... ) N
#define VA_ARG_COUNT( ... )                                             \
        _VA_ARG_COUNT ( __VA_ARGS__,                                    \
                        63, 62, 61, 60, 59, 58, 57, 56,                 \
                        55, 54, 53, 52, 51, 50, 49, 48,                 \
                        47, 46, 45, 44, 43, 42, 41, 40,                 \
                        39, 38, 37, 36, 35, 34, 33, 32,                 \
                        31, 30, 29, 28, 27, 26, 25, 24,                 \
                        23, 22, 21, 20, 19, 18, 17, 16,                 \
                        15, 14, 13, 12, 11, 10,  9,  8,                 \
                         7,  6,  5,  4,  3,  2,  1,  0 )

/** 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

/** Timeouts for sending DHCP packets */
#define DHCP_MIN_TIMEOUT ( 1 * TICKS_PER_SEC )
#define DHCP_MAX_TIMEOUT ( 10 * TICKS_PER_SEC )

/** Maximum time that we will wait for ProxyDHCP responses */
#define PROXYDHCP_MAX_TIMEOUT ( 2 * TICKS_PER_SEC )

/** Maximum time that we will wait for Boot Server responses */
#define PXEBS_MAX_TIMEOUT ( 3 * TICKS_PER_SEC )

/** 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 void * dhcp_chaddr ( struct net_device *netdev, uint8_t *hlen,
                            uint16_t *flags );
extern int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
                                struct net_device *netdev, uint8_t msgtype,
                                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, struct in_addr ciaddr,
                                 void *data, size_t max_len );
extern int start_dhcp ( struct job_interface *job, struct net_device *netdev );
extern int start_pxebs ( struct job_interface *job, struct net_device *netdev,
                         unsigned int pxe_type );

/* In environments that can provide cached DHCP packets, this function
 * should look for such a packet and call store_cached_dhcpack() with
 * it if it exists.
 */
__weak_decl ( void, get_cached_dhcpack, ( void ), (), );

extern void store_cached_dhcpack ( userptr_t data, size_t len );

#endif /* _GPXE_DHCP_H */