From 12da7ea475b2508e425df7481e634f099c36183c Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Sat, 15 Jul 2006 19:24:55 +0000 Subject: Add (untested) code for parsing a received DHCP packet and constructing a DHCP options block from the contents. --- src/include/gpxe/dhcp.h | 153 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 150 insertions(+), 3 deletions(-) (limited to 'src/include') diff --git a/src/include/gpxe/dhcp.h b/src/include/gpxe/dhcp.h index e34d5de5b..9442f8579 100644 --- a/src/include/gpxe/dhcp.h +++ b/src/include/gpxe/dhcp.h @@ -9,6 +9,87 @@ #include #include +#include + +/** + * A DHCP packet + * + */ +struct dhcp_packet { + /** Operation + * + * This must be either @c BOOTP_REQUEST or @c BOOTP_REPLY. + */ + uint8_t op; + /** Hardware address type + * + * This is an ARPHRD_XXX constant. + */ + 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 + */ + uint8_t sname[64]; + /** Boot file name (null terminated) + * + * This field may be overridden and contain DHCP options + */ + uint8_t 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. + */ + 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 + +/** DHCP magic cookie */ +#define DHCP_MAGIC_COOKIE 0x63825363UL /** Construct a tag value for an encapsulated option * @@ -22,7 +103,7 @@ #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 ) /** @@ -30,13 +111,80 @@ * @{ */ +/** Padding + * + * This tag does not have a length field; it is always only a single + * byte in length. + */ #define DHCP_PAD 0 -#define DHCP_END 255 +/** 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 + +/** 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 + +/** 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, 1 ) +/** "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, 2 ) + +/** "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, 3 ) + +/** End of options + * + * This tag does not have a length field; it is always only a single + * byte in length. + */ +#define DHCP_END 255 + /** @} */ /** @@ -118,7 +266,6 @@ extern struct dhcp_option * set_dhcp_option ( struct dhcp_option_block *options, unsigned int tag, const void *data, size_t len ); - /** * Find DHCP numerical option, and return its value * -- cgit v1.2.3-55-g7522