/*
* Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <gpxe/netdevice.h>
#include <gpxe/dhcp.h>
#include <gpxe/dhcpopts.h>
#include <gpxe/dhcppkt.h>
/** @file
*
* DHCP packets
*
*/
/** A dedicated field within a DHCP packet */
struct dhcp_packet_field {
/** Settings tag number */
unsigned int tag;
/** Offset within DHCP packet */
uint16_t offset;
/** Length of field */
uint16_t len;
};
/** Declare a dedicated field within a DHCP packet
*
* @v _tag Settings tag number
* @v _field Field name
*/
#define DHCP_PACKET_FIELD( _tag, _field ) { \
.tag = (_tag), \
.offset = offsetof ( struct dhcphdr, _field ), \
.len = sizeof ( ( ( struct dhcphdr * ) 0 )->_field ), \
}
/** Dedicated fields within a DHCP packet */
static struct dhcp_packet_field dhcp_packet_fields[] = {
DHCP_PACKET_FIELD ( DHCP_EB_YIADDR, yiaddr ),
DHCP_PACKET_FIELD ( DHCP_EB_SIADDR, siaddr ),
DHCP_PACKET_FIELD ( DHCP_TFTP_SERVER_NAME, sname ),
DHCP_PACKET_FIELD ( DHCP_BOOTFILE_NAME, file ),
};
/**
* Get address of a DHCP packet field
*
* @v dhcphdr DHCP packet header
* @v field DHCP packet field
* @ret data Packet field data
*/
static inline void * dhcp_packet_field ( struct dhcphdr *dhcphdr,
struct dhcp_packet_field *field ) {
return ( ( ( void * ) dhcphdr ) + field->offset );
}
/**
* Find DHCP packet field corresponding to settings tag number
*
* @v tag Settings tag number
* @ret field DHCP packet field, or NULL
*/
static struct dhcp_packet_field *
find_dhcp_packet_field ( unsigned int tag ) {
struct dhcp_packet_field *field;
unsigned int i;
for ( i = 0 ; i < ( sizeof ( dhcp_packet_fields ) /
sizeof ( dhcp_packet_fields[0] ) ) ; i++ ) {
field = &dhcp_packet_fields[i];
if ( field->tag == tag )
return field;
}
return NULL;
}
/**
* Store value of DHCP packet setting
*
* @v settings Settings block
* @v tag Setting tag number
* @v data Setting data, or NULL to clear setting
* @v len Length of setting data
* @ret rc Return status code
*/
static int dhcppkt_store ( struct settings *settings, unsigned int tag,
const void *data, size_t len ) {
struct dhcp_packet *dhcppkt =
container_of ( settings, struct dhcp_packet, settings );
struct dhcp_packet_field *field;
int rc;
/* If this is a special field, fill it in */
if ( ( field = find_dhcp_packet_field ( tag ) ) != NULL ) {
if ( len > field->len )
return -ENOSPC;
memcpy ( dhcp_packet_field ( dhcppkt->dhcphdr, field ),
data, len );
return 0;
}
/* Otherwise, use the generic options block */
rc = dhcpopt_store ( &dhcppkt->options, tag, data, len );
/* Update our used-length field */
dhcppkt->len = ( offsetof ( struct dhcphdr, options ) +
dhcppkt->options.len );
return rc;
}
/**
* Fetch value of DHCP packet setting
*
* @v settings Settings block
* @v tag Setting tag number
* @v data Buffer to fill with setting data
* @v len Length of buffer
* @ret len Length of setting data, or negative error
*/
static int dhcppkt_fetch ( struct settings *settings, unsigned int tag,
void *data, size_t len ) {
struct dhcp_packet *dhcppkt =
container_of ( settings, struct dhcp_packet, settings );
struct dhcp_packet_field *field;
/* If this is a special field, return it */
if ( ( field = find_dhcp_packet_field ( tag ) ) != NULL ) {
if ( len > field->len )
len = field->len;
memcpy ( data,
dhcp_packet_field ( dhcppkt->dhcphdr, field ), len );
return field->len;
}
/* Otherwise, use the generic options block */
return dhcpopt_fetch ( &dhcppkt->options, tag, data, len );
}
/** DHCP settings operations */
static struct settings_operations dhcppkt_settings_operations = {
.store = dhcppkt_store,
.fetch = dhcppkt_fetch,
};
/**
* Initialise prepopulated DHCP packet
*
* @v dhcppkt Uninitialised DHCP packet
* @v refcnt Reference counter of containing object, or NULL
* @v data Memory for DHCP packet data
* @v max_len Length of memory for DHCP packet data
*
* The memory content must already be filled with valid DHCP options.
* A zeroed block counts as a block of valid DHCP options.
*/
void dhcppkt_init ( struct dhcp_packet *dhcppkt, struct refcnt *refcnt,
void *data, size_t len ) {
dhcppkt->dhcphdr = data;
dhcppkt->max_len = len;
dhcpopt_init ( &dhcppkt->options, &dhcppkt->dhcphdr->options,
( len - offsetof ( struct dhcphdr, options ) ) );
dhcppkt->len = ( offsetof ( struct dhcphdr, options ) +
dhcppkt->options.len );
settings_init ( &dhcppkt->settings, &dhcppkt_settings_operations,
refcnt, "dhcp" );
}
