/*
* Copyright (C) 2006 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 <string.h>
#include <errno.h>
#include <assert.h>
#include <byteswap.h>
#include <gpxe/if_ether.h>
#include <gpxe/netdevice.h>
#include <gpxe/udp.h>
#include <gpxe/dhcp.h>
/** @file
*
* Dynamic Host Configuration Protocol
*
*/
/** DHCP operation types
*
* This table maps from DHCP message types (i.e. values of the @c
* DHCP_MESSAGE_TYPE option) to values of the "op" field within a DHCP
* packet.
*/
static const uint8_t dhcp_op[] = {
[DHCPDISCOVER] = BOOTP_REQUEST,
[DHCPOFFER] = BOOTP_REPLY,
[DHCPREQUEST] = BOOTP_REQUEST,
[DHCPDECLINE] = BOOTP_REQUEST,
[DHCPACK] = BOOTP_REPLY,
[DHCPNAK] = BOOTP_REPLY,
[DHCPRELEASE] = BOOTP_REQUEST,
[DHCPINFORM] = BOOTP_REQUEST,
};
/** Raw option data for options common to all DHCP requests */
static uint8_t dhcp_request_options_data[] = {
DHCP_MAX_MESSAGE_SIZE, DHCP_WORD ( ETH_MAX_MTU ),
DHCP_VENDOR_CLASS_ID,
DHCP_STRING ( 'E', 't', 'h', 'e', 'r', 'b', 'o', 'o', 't' ),
DHCP_PARAMETER_REQUEST_LIST,
DHCP_OPTION ( DHCP_SUBNET_MASK, DHCP_ROUTERS, DHCP_HOST_NAME ),
DHCP_END
};
/**
* Name a DHCP packet type
*
* @v msgtype DHCP message type
* @ret string DHCP mesasge type name
*/
static inline const char * dhcp_message_type_name ( unsigned int msgtype ) {
switch ( msgtype ) {
case DHCPDISCOVER: return "DHCPDISCOVER";
case DHCPOFFER: return "DHCPOFFER";
case DHCPREQUEST: return "DHCPREQUEST";
case DHCPDECLINE: return "DHCPDECLINE";
case DHCPACK: return "DHCPACK";
case DHCPNAK: return "DHCPNAK";
case DHCPRELEASE: return "DHCPRELEASE";
case DHCPINFORM: return "DHCPINFORM";
default: return "DHCP<invalid>";
}
}
/** Options common to all DHCP requests */
static struct dhcp_option_block dhcp_request_options = {
.data = dhcp_request_options_data,
.max_len = sizeof ( dhcp_request_options_data ),
.len = sizeof ( dhcp_request_options_data ),
};
/**
* Set option within DHCP packet
*
* @v dhcppkt DHCP packet
* @v tag DHCP option tag
* @v data New value for DHCP option
* @v len Length of value, in bytes
* @ret rc Return status code
*
* Sets the option within the first available options block within the
* DHCP packet. Option blocks are tried in the order specified by @c
* dhcp_option_block_fill_order.
*
* The magic options @c DHCP_EB_YIADDR and @c DHCP_EB_SIADDR are
* intercepted and inserted into the appropriate fixed fields within
* the DHCP packet. The option @c DHCP_OPTION_OVERLOAD is silently
* ignored, since our DHCP packet assembly method relies on always
* having option overloading in use.
*/
static int set_dhcp_packet_option ( struct dhcp_packet *dhcppkt,
unsigned int tag, const void *data,
size_t len ) {
struct dhcphdr *dhcphdr = dhcppkt->dhcphdr;
struct dhcp_option_block *options;
struct dhcp_option *option = NULL;
/* Special-case the magic options */
switch ( tag ) {
case DHCP_OPTION_OVERLOAD:
/* Hard-coded in packets we create; always ignore */
return 0;
case DHCP_EB_YIADDR:
memcpy ( &dhcphdr->yiaddr, data, sizeof ( dhcphdr->yiaddr ) );
return 0;
case DHCP_EB_SIADDR:
memcpy ( &dhcphdr->siaddr, data, sizeof ( dhcphdr->siaddr ) );
return 0;
default:
/* Continue processing as normal */
break;
}
/* Set option in first available options block */
for ( options = dhcppkt->options ;
options < &dhcppkt->options[NUM_OPT_BLOCKS] ; options++ ) {
option = set_dhcp_option ( options, tag, data, len );
if ( option )
break;
}
/* Update DHCP packet length */
dhcppkt->len = ( offsetof ( typeof ( *dhcppkt->dhcphdr ), options )
+ dhcppkt->options[OPTS_MAIN].len );
return ( option ? 0 : -ENOSPC );
}
/**
* Set options within DHCP packet
*
* @v dhcppkt DHCP packet
* @v options DHCP option block, or NULL
* @v encapsulator Encapsulating option, or zero
* @ret rc Return status code
*
* Copies options with the specified encapsulator from DHCP options
* blocks into a DHCP packet. Most options are copied verbatim.
* Recognised encapsulated options fields are handled as such.
*
* @c options may specify a single options block, or be left as NULL
* in order to copy options from all registered options blocks.
*/
static int set_dhcp_packet_encap_options ( struct dhcp_packet *dhcppkt,
struct dhcp_option_block *options,
unsigned int encapsulator ) {
unsigned int subtag;
unsigned int tag;
struct dhcp_option *option;
int rc;
for ( subtag = DHCP_MIN_OPTION; subtag <= DHCP_MAX_OPTION; subtag++ ) {
tag = DHCP_ENCAP_OPT ( encapsulator, subtag );
switch ( tag ) {
case DHCP_EB_ENCAP:
case DHCP_VENDOR_ENCAP:
/* Process encapsulated options field */
if ( ( rc = set_dhcp_packet_encap_options ( dhcppkt,
options,
tag )) !=0)
return rc;
break;
default:
/* Copy option to reassembled packet */
option = find_dhcp_option ( options, tag );
if ( ! option )
break;
if ( ( rc = set_dhcp_packet_option ( dhcppkt, tag,
&option->data,
option->len)) !=0)
return rc;
break;
};
}
return 0;
}
/**
* Set options within DHCP packet
*
* @v dhcppkt DHCP packet
* @v options DHCP option block, or NULL
* @ret rc Return status code
*
* Copies options from DHCP options blocks into a DHCP packet. Most
* options are copied verbatim. Recognised encapsulated options
* fields are handled as such.
*
* @c options may specify a single options block, or be left as NULL
* in order to copy options from all registered options blocks.
*/
static int set_dhcp_packet_options ( struct dhcp_packet *dhcppkt,
struct dhcp_option_block *options ) {
return set_dhcp_packet_encap_options ( dhcppkt, options, 0 );
}
/**
* Create a DHCP packet
*
* @v dhcp DHCP session
* @v msgtype DHCP message type
* @v data Buffer for DHCP packet
* @v max_len Size of DHCP packet buffer
* @v dhcppkt DHCP packet structure to fill in
* @ret rc Return status code
*
* Creates a DHCP packet in the specified buffer, and fills out a @c
* dhcp_packet structure that can be passed to
* set_dhcp_packet_option() or set_dhcp_packet_options().
*/
static int create_dhcp_packet ( struct dhcp_session *dhcp, uint8_t msgtype,
void *data, size_t max_len,
struct dhcp_packet *dhcppkt ) {
struct dhcphdr *dhcphdr = data;
static const uint8_t overloading = ( DHCP_OPTION_OVERLOAD_FILE |
DHCP_OPTION_OVERLOAD_SNAME );
int rc;
/* Sanity check */
if ( max_len < sizeof ( *dhcphdr ) )
return -ENOSPC;
/* Initialise DHCP packet content */
memset ( dhcphdr, 0, max_len );
dhcphdr->xid = dhcp->xid;
dhcphdr->magic = htonl ( DHCP_MAGIC_COOKIE );
dhcphdr->htype = ntohs ( dhcp->netdev->ll_protocol->ll_proto );
dhcphdr->hlen = dhcp->netdev->ll_protocol->ll_addr_len;
memcpy ( dhcphdr->chaddr, dhcp->netdev->ll_addr, dhcphdr->hlen );
dhcphdr->op = dhcp_op[msgtype];
/* Initialise DHCP packet structure */
dhcppkt->dhcphdr = dhcphdr;
dhcppkt->max_len = max_len;
init_dhcp_options ( &dhcppkt->options[OPTS_MAIN], dhcphdr->options,
( max_len -
offsetof ( typeof ( *dhcphdr ), options ) ) );
init_dhcp_options ( &dhcppkt->options[OPTS_FILE], dhcphdr->file,
sizeof ( dhcphdr->file ) );
init_dhcp_options ( &dhcppkt->options[OPTS_SNAME], dhcphdr->sname,
sizeof ( dhcphdr->sname ) );
/* Set DHCP_OPTION_OVERLOAD option within the main options block */
if ( set_dhcp_option ( &dhcppkt->options[OPTS_MAIN],
DHCP_OPTION_OVERLOAD, &overloading,
sizeof ( overloading ) ) == NULL )
return -ENOSPC;
/* Set DHCP_MESSAGE_TYPE option */
if ( ( rc = set_dhcp_packet_option ( dhcppkt, DHCP_MESSAGE_TYPE,
&msgtype,
sizeof ( msgtype ) ) ) != 0 )
return rc;
return 0;
}
/**
* Calculate used length of a field containing DHCP options
*
* @v data Field containing DHCP options
* @v max_len Field length
* @ret len Used length (excluding the @c DHCP_END tag)
*/
static size_t dhcp_field_len ( const void *data, size_t max_len ) {
struct dhcp_option_block options;
struct dhcp_option *end;
options.data = ( ( void * ) data );
options.len = max_len;
end = find_dhcp_option ( &options, DHCP_END );
return ( end ? ( ( ( void * ) end ) - data ) : 0 );
}
/**
* Merge field containing DHCP options or string into DHCP options block
*
* @v options DHCP option block
* @v data Field containing DHCP options
* @v max_len Field length
* @v tag DHCP option tag, or 0
*
* If @c tag is non-zero, the field will be treated as a
* NUL-terminated string representing the value of the specified DHCP
* option. If @c tag is zero, the field will be treated as a block of
* DHCP options, and simply appended to the existing options in the
* option block.
*
* The caller must ensure that there is enough space in the options
* block to perform the merge.
*/
static void merge_dhcp_field ( struct dhcp_option_block *options,
const void *data, size_t max_len,
unsigned int tag ) {
size_t len;
void *dest;
struct dhcp_option *end;
if ( tag ) {
set_dhcp_option ( options, tag, data, strlen ( data ) );
} else {
len = dhcp_field_len ( data, max_len );
dest = ( options->data + options->len - 1 );
memcpy ( dest, data, len );
options->len += len;
end = ( dest + len );
end->tag = DHCP_END;
}
}
/**
* Parse DHCP packet and construct DHCP options block
*
* @v dhcphdr DHCP packet
* @v len Length of DHCP packet
* @ret options DHCP options block, or NULL
*
* Parses a received DHCP packet and canonicalises its contents into a
* single DHCP options block. The "file" and "sname" fields are
* converted into the corresponding DHCP options (@c
* DHCP_BOOTFILE_NAME and @c DHCP_TFTP_SERVER_NAME respectively). If
* these fields are used for option overloading, their options are
* merged in to the options block.
*
* The values of the "yiaddr" and "siaddr" fields will be stored
* within the options block as the magic options @c DHCP_EB_YIADDR and
* @c DHCP_EB_SIADDR.
*
* Note that this call allocates new memory for the constructed DHCP
* options block; it is the responsibility of the caller to eventually
* free this memory.
*/
static struct dhcp_option_block * dhcp_parse ( struct dhcphdr *dhcphdr,
size_t len ) {
struct dhcp_option_block *options;
size_t options_len;
unsigned int overloading;
/* Sanity check */
if ( len < sizeof ( *dhcphdr ) )
return NULL;
/* Calculate size of resulting concatenated option block:
*
* The "options" field : length of the field minus the DHCP_END tag.
*
* The "file" field : maximum length of the field minus the
* NUL terminator, plus a 2-byte DHCP header or, if used for
* option overloading, the length of the field minus the
* DHCP_END tag.
*
* The "sname" field : as for the "file" field.
*
* 15 bytes for an encapsulated options field to contain the
* value of the "yiaddr" and "siaddr" fields
*
* 1 byte for a final terminating DHCP_END tag.
*/
options_len = ( ( len - offsetof ( typeof ( *dhcphdr ), options ) ) - 1
+ ( sizeof ( dhcphdr->file ) + 1 )
+ ( sizeof ( dhcphdr->sname ) + 1 )
+ 15 /* yiaddr and siaddr */
+ 1 /* DHCP_END tag */ );
/* Allocate empty options block of required size */
options = alloc_dhcp_options ( options_len );
if ( ! options ) {
DBG ( "DHCP could not allocate %d-byte option block\n",
options_len );
return NULL;
}
/* Merge in "options" field, if this is a DHCP packet */
if ( dhcphdr->magic == htonl ( DHCP_MAGIC_COOKIE ) ) {
merge_dhcp_field ( options, dhcphdr->options,
( len -
offsetof ( typeof (*dhcphdr), options ) ),
0 /* Always contains options */ );
}
/* Identify overloaded fields */
overloading = find_dhcp_num_option ( options, DHCP_OPTION_OVERLOAD );
/* Merge in "file" and "sname" fields */
merge_dhcp_field ( options, dhcphdr->file, sizeof ( dhcphdr->file ),
( ( overloading & DHCP_OPTION_OVERLOAD_FILE ) ?
DHCP_BOOTFILE_NAME : 0 ) );
merge_dhcp_field ( options, dhcphdr->sname, sizeof ( dhcphdr->sname ),
( ( overloading & DHCP_OPTION_OVERLOAD_SNAME ) ?
DHCP_TFTP_SERVER_NAME : 0 ) );
/* Set magic options for "yiaddr" and "siaddr", if present */
if ( dhcphdr->yiaddr.s_addr ) {
set_dhcp_option ( options, DHCP_EB_YIADDR,
&dhcphdr->yiaddr, sizeof (dhcphdr->yiaddr) );
}
if ( dhcphdr->siaddr.s_addr ) {
set_dhcp_option ( options, DHCP_EB_SIADDR,
&dhcphdr->siaddr, sizeof (dhcphdr->siaddr) );
}
assert ( options->len <= options->max_len );
return options;
}
/****************************************************************************
*
* DHCP to UDP interface
*
*/
static inline struct dhcp_session *
udp_to_dhcp ( struct udp_connection *conn ) {
return container_of ( conn, struct dhcp_session, udp );
}
/** Address for transmitting DHCP requests */
static struct sockaddr sa_dhcp_server = {
.sa_family = AF_INET,
.sin = {
.sin_addr.s_addr = INADDR_BROADCAST,
.sin_port = htons ( BOOTPS_PORT ),
},
};
/**
* Transmit DHCP request
*
* @v conn UDP connection
* @v buf Temporary data buffer
* @v len Length of temporary data buffer
*/
static void dhcp_senddata ( struct udp_connection *conn,
void *buf, size_t len ) {
struct dhcp_session *dhcp = udp_to_dhcp ( conn );
struct dhcp_packet dhcppkt;
int rc;
DBG ( "Transmitting %s\n", dhcp_message_type_name ( dhcp->state ) );
assert ( ( dhcp->state == DHCPDISCOVER ) ||
( dhcp->state == DHCPREQUEST ) );
/* Create DHCP packet in temporary buffer */
if ( ( rc = create_dhcp_packet ( dhcp, dhcp->state, buf, len,
&dhcppkt ) ) != 0 ) {
DBG ( "Could not create DHCP packet\n" );
return;
}
/* Copy in options common to all requests */
if ( ( rc = set_dhcp_packet_options ( &dhcppkt,
&dhcp_request_options ) ) != 0 ){
DBG ( "Could not set common DHCP options\n" );
return;
}
/* Transmit the packet */
if ( ( rc = udp_sendto ( conn, &sa_dhcp_server,
dhcppkt.dhcphdr, dhcppkt.len ) ) != 0 ) {
DBG ( "Could not transmit UDP packet\n" );
return;
}
}
/**
* Receive new data
*
* @v udp UDP connection
* @v data Received data
* @v len Length of received data
*/
static void dhcp_newdata ( struct udp_connection *conn,
void *data, size_t len ) {
struct dhcp_session *dhcp = udp_to_dhcp ( conn );
struct dhcphdr *dhcphdr = data;
struct dhcp_option_block *options;
/* Check for matching transaction ID */
if ( dhcphdr->xid != dhcp->xid ) {
DBG ( "DHCP wrong transaction ID (wanted %08lx, got %08lx)\n",
ntohl ( dhcphdr->xid ), ntohl ( dhcp->xid ) );
return;
};
/* Parse packet and create options structure */
options = dhcp_parse ( dhcphdr, len );
if ( ! options ) {
DBG ( "Could not parse DHCP packet\n" );
return;
}
DBG ( "Received %s\n",
dhcp_message_type_name ( find_dhcp_num_option ( options,
DHCP_MESSAGE_TYPE ) ) );
/* Proof of concept: just dump out the parsed options */
hex_dump ( options->data, options->len );
free_dhcp_options ( options );
}
/** DHCP UDP operations */
static struct udp_operations dhcp_udp_operations = {
.senddata = dhcp_senddata,
.newdata = dhcp_newdata,
};
/**
* Initiate DHCP on a network interface
*
* @v dhcp DHCP session
* @ret aop Asynchronous operation
*/
struct async_operation * start_dhcp ( struct dhcp_session *dhcp ) {
int rc;
dhcp->udp.udp_op = &dhcp_udp_operations;
dhcp->state = DHCPDISCOVER;
/* Use least significant 32 bits of link-layer address as XID */
memcpy ( &dhcp->xid, ( dhcp->netdev->ll_addr
+ dhcp->netdev->ll_protocol->ll_addr_len
- sizeof ( dhcp->xid ) ), sizeof ( dhcp->xid ));
/* Bind to local port */
if ( ( rc = udp_open ( &dhcp->udp, htons ( BOOTPC_PORT ) ) ) != 0 ) {
async_done ( &dhcp->aop, rc );
goto out;
}
/* Proof of concept: just send a single DHCPDISCOVER */
udp_senddata ( &dhcp->udp );
out:
return &dhcp->aop;
}
