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is a DHCP option" data structures. We need this code in order to be able to return a DHCP packet to a PXE NBP which reflects options from our multiple sources (e.g. NVS and DHCP server). This is expensive, but necessary. Having paid this cost, we may as well try to use the same code to generate our DHCP request packets, since the process is similar.
340 lines
9.2 KiB
C
340 lines
9.2 KiB
C
#ifndef _GPXE_DHCP_H
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#define _GPXE_DHCP_H
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/** @file
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*
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* Dynamic Host Configuration Protocol
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*
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*/
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#include <stdint.h>
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#include <gpxe/list.h>
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#include <gpxe/in.h>
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/**
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* A DHCP packet
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*
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*/
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struct dhcp_packet {
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/** Operation
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*
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* This must be either @c BOOTP_REQUEST or @c BOOTP_REPLY.
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*/
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uint8_t op;
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/** Hardware address type
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*
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* This is an ARPHRD_XXX constant.
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*/
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uint8_t htype;
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/** Hardware address length */
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uint8_t hlen;
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/** Number of hops from server */
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uint8_t hops;
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/** Transaction ID */
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uint32_t xid;
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/** Seconds since start of acquisition */
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uint16_t secs;
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/** Flags */
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uint16_t flags;
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/** "Client" IP address
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*
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* This is filled in if the client already has an IP address
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* assigned and can respond to ARP requests.
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*/
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struct in_addr ciaddr;
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/** "Your" IP address
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*
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* This is the IP address assigned by the server to the client.
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*/
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struct in_addr yiaddr;
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/** "Server" IP address
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*
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* This is the IP address of the next server to be used in the
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* boot process.
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*/
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struct in_addr siaddr;
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/** "Gateway" IP address
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*
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* This is the IP address of the DHCP relay agent, if any.
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*/
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struct in_addr giaddr;
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/** Client hardware address */
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uint8_t chaddr[16];
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/** Server host name (null terminated)
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*
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* This field may be overridden and contain DHCP options
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*/
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uint8_t sname[64];
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/** Boot file name (null terminated)
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*
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* This field may be overridden and contain DHCP options
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*/
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uint8_t file[128];
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/** DHCP magic cookie
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*
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* Must have the value @c DHCP_MAGIC_COOKIE.
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*/
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uint32_t magic;
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/** DHCP options
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*
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* Variable length; extends to the end of the packet.
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*/
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uint8_t options[0];
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};
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/** Opcode for a request from client to server */
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#define BOOTP_REQUEST 1
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/** Opcode for a reply from server to client */
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#define BOOTP_REPLY 2
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/** DHCP magic cookie */
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#define DHCP_MAGIC_COOKIE 0x63825363UL
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/** Construct a tag value for an encapsulated option
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*
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* This tag value can be passed to Etherboot functions when searching
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* for DHCP options in order to search for a tag within an
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* encapsulated options block.
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*/
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#define DHCP_ENCAP_OPT( encapsulator, encapsulated ) \
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( ( (encapsulator) << 8 ) | (encapsulated) )
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/** Extract encapsulating option block tag from encapsulated tag value */
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#define DHCP_ENCAPSULATOR( encap_opt ) ( (encap_opt) >> 8 )
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/** Extract encapsulated option tag from encapsulated tag value */
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#define DHCP_ENCAPSULATED( encap_opt ) ( (encap_opt) & 0xff )
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/** Option is encapsulated */
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#define DHCP_IS_ENCAP_OPT( opt ) DHCP_ENCAPSULATOR( opt )
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/**
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* @defgroup dhcpopts DHCP option tags
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* @{
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*/
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/** Padding
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*
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* This tag does not have a length field; it is always only a single
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* byte in length.
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*/
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#define DHCP_PAD 0
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/** Minimum normal DHCP option */
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#define DHCP_MIN_OPTION 1
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/** Vendor encapsulated options */
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#define DHCP_VENDOR_ENCAP 43
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/** Option overloading
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*
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* The value of this option is the bitwise-OR of zero or more
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* DHCP_OPTION_OVERLOAD_XXX constants.
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*/
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#define DHCP_OPTION_OVERLOAD 52
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/** The "file" field is overloaded to contain extra DHCP options */
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#define DHCP_OPTION_OVERLOAD_FILE 1
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/** The "sname" field is overloaded to contain extra DHCP options */
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#define DHCP_OPTION_OVERLOAD_SNAME 2
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/** DHCP message type */
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#define DHCP_MESSAGE_TYPE 53
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#define DHCPDISCOVER 1
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#define DHCPOFFER 2
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#define DHCPREQUEST 3
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#define DHCPDECLINE 4
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#define DHCPACK 5
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#define DHCPNAK 6
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#define DHCPRELEASE 7
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#define DHCPINFORM 8
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/** TFTP server name
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*
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* This option replaces the fixed "sname" field, when that field is
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* used to contain overloaded options.
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*/
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#define DHCP_TFTP_SERVER_NAME 66
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/** Bootfile name
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*
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* This option replaces the fixed "file" field, when that field is
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* used to contain overloaded options.
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*/
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#define DHCP_BOOTFILE_NAME 67
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/** Etherboot-specific encapsulated options
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*
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* This encapsulated options field is used to contain all options
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* specific to Etherboot (i.e. not assigned by IANA or other standards
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* bodies).
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*/
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#define DHCP_EB_ENCAP 175
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/** Priority of this options block
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*
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* This is a signed 8-bit integer field indicating the priority of
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* this block of options. It can be used to specify the relative
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* priority of multiple option blocks (e.g. options from non-volatile
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* storage versus options from a DHCP server).
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*/
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#define DHCP_EB_PRIORITY DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 1 )
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/** "Your" IP address
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*
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* This option is used internally to contain the value of the "yiaddr"
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* field, in order to provide a consistent approach to storing and
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* processing options. It should never be present in a DHCP packet.
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*/
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#define DHCP_EB_YIADDR DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 2 )
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/** "Server" IP address
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*
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* This option is used internally to contain the value of the "siaddr"
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* field, in order to provide a consistent approach to storing and
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* processing options. It should never be present in a DHCP packet.
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*/
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#define DHCP_EB_SIADDR DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 3 )
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/** Maximum normal DHCP option */
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#define DHCP_MAX_OPTION 254
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/** End of options
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*
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* This tag does not have a length field; it is always only a single
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* byte in length.
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*/
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#define DHCP_END 255
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/** @} */
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/**
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* A DHCP option
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*
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* DHCP options consist of a mandatory tag, a length field that is
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* mandatory for all options except @c DHCP_PAD and @c DHCP_END, and a
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* payload.
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*/
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struct dhcp_option {
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/** Tag
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*
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* Must be a @c DHCP_XXX value.
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*/
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uint8_t tag;
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/** Length
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*
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* This is the length of the data field (i.e. excluding the
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* tag and length fields). For the two tags @c DHCP_PAD and
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* @c DHCP_END, the length field is implicitly zero and is
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* also missing, i.e. these DHCP options are only a single
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* byte in length.
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*/
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uint8_t len;
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/** Option data
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*
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* Interpretation of the content is entirely dependent upon
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* the tag. For fields containing a multi-byte integer, the
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* field is defined to be in network-endian order (unless you
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* are Intel and feel like violating the spec for fun).
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*/
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union {
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uint8_t byte;
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uint16_t word;
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uint32_t dword;
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uint8_t bytes[0];
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} data;
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} __attribute__ (( packed ));
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/**
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* Length of a DHCP option header
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*
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* The header is the portion excluding the data, i.e. the tag and the
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* length.
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*/
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#define DHCP_OPTION_HEADER_LEN ( offsetof ( struct dhcp_option, data ) )
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/** Maximum length for a single DHCP option */
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#define DHCP_MAX_LEN 0xff
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/** A DHCP options block */
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struct dhcp_option_block {
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/** List of option blocks */
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struct list_head list;
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/** Option block raw data */
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void *data;
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/** Option block length */
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size_t len;
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/** Option block maximum length */
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size_t max_len;
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/** Block priority
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*
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* This is determined at the time of the call to
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* register_options() by searching for the @c DHCP_EB_PRIORITY
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* option.
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*/
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signed int priority;
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};
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extern unsigned long dhcp_num_option ( struct dhcp_option *option );
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extern struct dhcp_option *
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find_dhcp_option ( struct dhcp_option_block *options, unsigned int tag );
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extern struct dhcp_option * find_global_dhcp_option ( unsigned int tag );
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extern void register_dhcp_options ( struct dhcp_option_block *options );
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extern void unregister_dhcp_options ( struct dhcp_option_block *options );
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extern void init_dhcp_options ( struct dhcp_option_block *options,
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void *data, size_t max_len );
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extern struct dhcp_option_block * alloc_dhcp_options ( size_t max_len );
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extern void free_dhcp_options ( struct dhcp_option_block *options );
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extern struct dhcp_option *
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set_dhcp_option ( struct dhcp_option_block *options, unsigned int tag,
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const void *data, size_t len );
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/**
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* Find DHCP numerical option, and return its value
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*
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* @v options DHCP options block
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* @v tag DHCP option tag to search for
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* @ret value Numerical value of the option, or 0 if not found
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*
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* This function exists merely as a notational shorthand for a call to
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* find_dhcp_option() followed by a call to dhcp_num_option(). It is
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* not possible to distinguish between the cases "option not found"
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* and "option has a value of zero" using this function; if this
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* matters to you then issue the two constituent calls directly and
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* check that find_dhcp_option() returns a non-NULL value.
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*/
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static inline unsigned long
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find_dhcp_num_option ( struct dhcp_option_block *options, unsigned int tag ) {
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return dhcp_num_option ( find_dhcp_option ( options, tag ) );
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}
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/**
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* Find DHCP numerical option, and return its value
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*
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* @v tag DHCP option tag to search for
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* @ret value Numerical value of the option, or 0 if not found
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*
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* This function exists merely as a notational shorthand for a call to
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* find_global_dhcp_option() followed by a call to dhcp_num_option().
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* It is not possible to distinguish between the cases "option not
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* found" and "option has a value of zero" using this function; if
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* this matters to you then issue the two constituent calls directly
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* and check that find_global_dhcp_option() returns a non-NULL value.
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*/
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static inline unsigned long
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find_global_dhcp_num_option ( unsigned int tag ) {
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return dhcp_num_option ( find_global_dhcp_option ( tag ) );
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}
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/**
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* Delete DHCP option
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*
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* @v options DHCP options block
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* @v tag DHCP option tag
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*/
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static inline void delete_dhcp_option ( struct dhcp_option_block *options,
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unsigned int tag ) {
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set_dhcp_option ( options, tag, NULL, 0 );
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}
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#endif /* _GPXE_DHCP_H */
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