/*
* 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.
*/
FILE_LICENCE ( GPL2_OR_LATER );
#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
*
*/
/****************************************************************************
*
* DHCP packet raw interface
*
*/
/**
* Calculate used length of an IPv4 field within a DHCP packet
*
* @v data Field data
* @v len Length of field
* @ret used Used length of field
*/
static size_t used_len_ipv4 ( const void *data, size_t len __unused ) {
const struct in_addr *in = data;
return ( in->s_addr ? sizeof ( *in ) : 0 );
}
/**
* Calculate used length of a string field within a DHCP packet
*
* @v data Field data
* @v len Length of field
* @ret used Used length of field
*/
static size_t used_len_string ( const void *data, size_t len ) {
return strnlen ( data, len );
}
/** 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;
/** Calculate used length of field
*
* @v data Field data
* @v len Length of field
* @ret used Used length of field
*/
size_t ( * used_len ) ( const void *data, size_t len );
};
/** Declare a dedicated field within a DHCP packet
*
* @v _tag Settings tag number
* @v _field Field name
* @v _used_len Function to calculate used length of field
*/
#define DHCP_PACKET_FIELD( _tag, _field, _used_len ) { \
.tag = (_tag), \
.offset = offsetof ( struct dhcphdr, _field ), \
.len = sizeof ( ( ( struct dhcphdr * ) 0 )->_field ), \
.used_len = _used_len, \
}
/** Dedicated fields within a DHCP packet */
static struct dhcp_packet_field dhcp_packet_fields[] = {
DHCP_PACKET_FIELD ( DHCP_EB_YIADDR, yiaddr, used_len_ipv4 ),
DHCP_PACKET_FIELD ( DHCP_EB_SIADDR, siaddr, used_len_ipv4 ),
DHCP_PACKET_FIELD ( DHCP_TFTP_SERVER_NAME, sname, used_len_string ),
DHCP_PACKET_FIELD ( DHCP_BOOTFILE_NAME, file, used_len_string ),
};
/**
* 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 dhcppkt DHCP packet
* @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
*/
int dhcppkt_store ( struct dhcp_packet *dhcppkt, unsigned int tag,
const void *data, size_t len ) {
struct dhcp_packet_field *field;
void *field_data;
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;
field_data = dhcp_packet_field ( dhcppkt->dhcphdr, field );
memset ( field_data, 0, field->len );
memcpy ( dhcp_packet_field ( dhcppkt->dhcphdr, field ),
data, len );
/* Erase any equivalent option from the options block */
dhcpopt_store ( &dhcppkt->options, tag, NULL, 0 );
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 dhcppkt DHCP packet
* @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
*/
int dhcppkt_fetch ( struct dhcp_packet *dhcppkt, unsigned int tag,
void *data, size_t len ) {
struct dhcp_packet_field *field;
void *field_data;
size_t field_len = 0;
/* Identify special field, if any */
if ( ( field = find_dhcp_packet_field ( tag ) ) != NULL ) {
field_data = dhcp_packet_field ( dhcppkt->dhcphdr, field );
field_len = field->used_len ( field_data, field->len );
}
/* Return special field, if it exists and is populated */
if ( field_len ) {
if ( len > field_len )
len = field_len;
memcpy ( data, field_data, len );
return field_len;
}
/* Otherwise, use the generic options block */
return dhcpopt_fetch ( &dhcppkt->options, tag, data, len );
}
/****************************************************************************
*
* DHCP packet settings interface
*
*/
/**
* Store value of DHCP setting
*
* @v settings Settings block
* @v setting Setting to store
* @v data Setting data, or NULL to clear setting
* @v len Length of setting data
* @ret rc Return status code
*/
static int dhcppkt_settings_store ( struct settings *settings,
struct setting *setting,
const void *data, size_t len ) {
struct dhcp_packet *dhcppkt =
container_of ( settings, struct dhcp_packet, settings );
return dhcppkt_store ( dhcppkt, setting->tag, data, len );
}
/**
* Fetch value of DHCP setting
*
* @v settings Settings block, or NULL to search all blocks
* @v setting Setting to fetch
* @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_settings_fetch ( struct settings *settings,
struct setting *setting,
void *data, size_t len ) {
struct dhcp_packet *dhcppkt =
container_of ( settings, struct dhcp_packet, settings );
return dhcppkt_fetch ( dhcppkt, setting->tag, data, len );
}
/** DHCP settings operations */
static struct settings_operations dhcppkt_settings_operations = {
.store = dhcppkt_settings_store,
.fetch = dhcppkt_settings_fetch,
};
/****************************************************************************
*
* Constructor
*
*/
/**
* Initialise DHCP packet
*
* @v dhcppkt DHCP packet structure to fill in
* @v data DHCP packet raw data
* @v max_len Length of raw data buffer
*
* Initialise a DHCP packet structure from a data buffer containing a
* DHCP packet.
*/
void dhcppkt_init ( struct dhcp_packet *dhcppkt, struct dhcphdr *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, &dhcppkt->refcnt,
DHCP_SETTINGS_NAME, 0 );
}