dhcppkt.c File Reference

DHCP packets. More...

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <ipxe/netdevice.h>
#include <ipxe/dhcp.h>
#include <ipxe/dhcpopts.h>
#include <ipxe/dhcppkt.h>

Go to the source code of this file.

Data Structures
struct	dhcp_packet_field
	A dedicated field within a DHCP packet. More...

Macros
#define	DHCP_PACKET_FIELD(_tag, _field, _used_len)
	Declare a dedicated field within a DHCP packet. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static size_t	used_len_ipv4 (const void *data, size_t len __unused)
	Calculate used length of an IPv4 field within a DHCP packet. More...
static size_t	used_len_string (const void *data, size_t len)
	Calculate used length of a string field within a DHCP packet. More...
static void *	dhcp_packet_field (struct dhcphdr *dhcphdr, struct dhcp_packet_field *field)
	Get address of a DHCP packet field. More...
static struct dhcp_packet_field *	find_dhcp_packet_field (unsigned int tag)
	Find DHCP packet field corresponding to settings tag number. More...
static int	dhcppkt_applies (struct dhcp_packet *dhcppkt __unused, unsigned int tag)
	Check applicability of DHCP setting. More...
int	dhcppkt_store (struct dhcp_packet *dhcppkt, unsigned int tag, const void *data, size_t len)
	Store value of DHCP packet setting. More...
int	dhcppkt_fetch (struct dhcp_packet *dhcppkt, unsigned int tag, void *data, size_t len)
	Fetch value of DHCP packet setting. More...
static int	dhcppkt_settings_applies (struct settings *settings, const struct setting *setting)
	Check applicability of DHCP setting. More...
static int	dhcppkt_settings_store (struct settings *settings, const struct setting *setting, const void *data, size_t len)
	Store value of DHCP setting. More...
static int	dhcppkt_settings_fetch (struct settings *settings, struct setting *setting, void *data, size_t len)
	Fetch value of DHCP setting. More...
void	dhcppkt_init (struct dhcp_packet *dhcppkt, struct dhcphdr *data, size_t len)
	Initialise DHCP packet. More...

Variables
static struct dhcp_packet_field	dhcp_packet_fields []
	Dedicated fields within a DHCP packet. More...
static struct settings_operations	dhcppkt_settings_operations
	DHCP settings operations. More...

Detailed Description

DHCP packets.

Definition in file dhcppkt.c.

Macro Definition Documentation

DHCP_PACKET_FIELD

#define DHCP_PACKET_FIELD	(		_tag,
			_field,
			_used_len
	)

Value:

{                       \
                .tag = (_tag),                                          \
                .offset = offsetof ( struct dhcphdr, _field ),          \
                .len = sizeof ( ( ( struct dhcphdr * ) 0 )->_field ),   \
                .used_len = _used_len,                                  \
        }

Declare a dedicated field within a DHCP packet.

Parameters

_tag	Settings tag number
_field	Field name
_used_len	Function to calculate used length of field

Definition at line 95 of file dhcppkt.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

used_len_ipv4()

static size_t used_len_ipv4 ( const void *  data, size_t len  __unused  )

static

Calculate used length of an IPv4 field within a DHCP packet.

Parameters

data	Field data
len	Length of field

Return values

used	Used length of field

Definition at line 55 of file dhcppkt.c.

                                                                      {
        const struct in_addr *in = data;

        return ( in->s_addr ? sizeof ( *in ) : 0 );
}

References data, and in.

used_len_string()

static size_t used_len_string ( const void *  data, size_t  len  )

static

Calculate used length of a string field within a DHCP packet.

Parameters

data	Field data
len	Length of field

Return values

used	Used length of field

Definition at line 68 of file dhcppkt.c.

                                                               {
        return strnlen ( data, len );
}

References data, len, and strnlen().

dhcp_packet_field()

static void* dhcp_packet_field ( struct dhcphdr *  dhcphdr, struct dhcp_packet_field *  field  )

inlinestatic

Get address of a DHCP packet field.

Parameters

dhcphdr	DHCP packet header
field	DHCP packet field

Return values

data	Packet field data

Definition at line 117 of file dhcppkt.c.

                                                                           {
        return ( ( ( void * ) dhcphdr ) + field->offset );
}

References dhcp_packet_field::offset.

Referenced by dhcppkt_fetch(), and dhcppkt_store().

find_dhcp_packet_field()

static struct dhcp_packet_field* find_dhcp_packet_field ( unsigned int  tag )

static

Find DHCP packet field corresponding to settings tag number.

Parameters

tag	Settings tag number

Return values

field

DHCP packet field, or NULL

Definition at line 129 of file dhcppkt.c.

                                            {
        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;
}

References dhcp_packet_fields, NULL, tag, and dhcp_packet_field::tag.

Referenced by dhcppkt_fetch(), and dhcppkt_store().

dhcppkt_applies()

static int dhcppkt_applies ( struct dhcp_packet *dhcppkt  __unused, unsigned int  tag  )

static

Check applicability of DHCP setting.

Parameters

dhcppkt	DHCP packet
tag	Setting tag number

Return values

applies

Setting applies within this settings block

Definition at line 149 of file dhcppkt.c.

                                                {

        return dhcpopt_applies ( tag );
}

References dhcpopt_applies(), and tag.

Referenced by dhcppkt_settings_applies().

dhcppkt_store()

int dhcppkt_store	(	struct dhcp_packet *	dhcppkt,
		unsigned int	tag,
		const void *	data,
		size_t	len
	)

Store value of DHCP packet setting.

Parameters

dhcppkt	DHCP packet
tag	Setting tag number
data	Setting data, or NULL to clear setting
len	Length of setting data

Return values

rc	Return status code

Definition at line 164 of file dhcppkt.c.

                                                   {
        struct dhcp_packet_field *field;
        void *field_data;

        /* 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 */
        return dhcpopt_store ( &dhcppkt->options, tag, data, len );
}

References data, dhcp_packet_field(), dhcp_packet::dhcphdr, dhcpopt_store(), ENOSPC, find_dhcp_packet_field(), len, dhcp_packet_field::len, memcpy(), memset(), NULL, dhcp_packet::options, and tag.

Referenced by copy_encap_settings(), dhcp_create_packet(), dhcp_create_request(), dhcp_proxy_tx(), dhcp_pxebs_tx(), dhcp_request_tx(), and dhcppkt_settings_store().

dhcppkt_fetch()

int dhcppkt_fetch	(	struct dhcp_packet *	dhcppkt,
		unsigned int	tag,
		void *	data,
		size_t	len
	)

Fetch value of DHCP packet setting.

Parameters

dhcppkt	DHCP packet
tag	Setting tag number
data	Buffer to fill with setting data
len	Length of buffer

Return values

len	Length of setting data, or negative error

Definition at line 195 of file dhcppkt.c.

                                             {
        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 );
}

References data, dhcp_packet_field(), dhcp_packet::dhcphdr, dhcpopt_fetch(), find_dhcp_packet_field(), len, dhcp_packet_field::len, memcpy(), NULL, dhcp_packet::options, tag, and dhcp_packet_field::used_len.

Referenced by dhcp_deliver(), dhcp_discovery_rx(), dhcp_has_pxeopts(), dhcp_pxebs_rx(), and dhcppkt_settings_fetch().

dhcppkt_settings_applies()

static int dhcppkt_settings_applies ( struct settings *  settings, const struct setting *  setting  )

static

Check applicability of DHCP setting.

Parameters

settings	Settings block
setting	Setting

Return values

applies

Setting applies within this settings block

Definition at line 232 of file dhcppkt.c.

                                                                      {
        struct dhcp_packet *dhcppkt =
                container_of ( settings, struct dhcp_packet, settings );

        return ( ( setting->scope == NULL ) &&
                 dhcppkt_applies ( dhcppkt, setting->tag ) );
}

References container_of, dhcppkt_applies(), NULL, setting::scope, and setting::tag.

dhcppkt_settings_store()

static int dhcppkt_settings_store ( struct settings *  settings, const struct setting *  setting, const void *  data, size_t  len  )

static

Store value of DHCP setting.

Parameters

settings	Settings block
setting	Setting to store
data	Setting data, or NULL to clear setting
len	Length of setting data

Return values

rc	Return status code

Definition at line 250 of file dhcppkt.c.

                                                                   {
        struct dhcp_packet *dhcppkt =
                container_of ( settings, struct dhcp_packet, settings );

        return dhcppkt_store ( dhcppkt, setting->tag, data, len );
}

References container_of, data, dhcppkt_store(), len, and setting::tag.

dhcppkt_settings_fetch()

static int dhcppkt_settings_fetch ( struct settings *  settings, struct setting *  setting, void *  data, size_t  len  )

static

Fetch value of DHCP setting.

Parameters

settings	Settings block, or NULL to search all blocks
setting	Setting to fetch
data	Buffer to fill with setting data
len	Length of buffer

Return values

len	Length of setting data, or negative error

Definition at line 268 of file dhcppkt.c.

                                                             {
        struct dhcp_packet *dhcppkt =
                container_of ( settings, struct dhcp_packet, settings );

        return dhcppkt_fetch ( dhcppkt, setting->tag, data, len );
}

References container_of, data, dhcppkt_fetch(), len, and setting::tag.

dhcppkt_init()

void dhcppkt_init	(	struct dhcp_packet *	dhcppkt,
		struct dhcphdr *	data,
		size_t	len
	)

Initialise DHCP packet.

Parameters

dhcppkt	DHCP packet structure to fill in
data	DHCP packet raw data
max_len	Length of raw data buffer

Initialise a DHCP packet structure from a data buffer containing a DHCP packet.

Definition at line 300 of file dhcppkt.c.

                                 {
        ref_init ( &dhcppkt->refcnt, NULL );
        dhcppkt->dhcphdr = data;
        dhcpopt_init ( &dhcppkt->options, &dhcppkt->dhcphdr->options,
                       ( len - offsetof ( struct dhcphdr, options ) ),
                       dhcpopt_no_realloc );
        settings_init ( &dhcppkt->settings, &dhcppkt_settings_operations,
                        &dhcppkt->refcnt, NULL );
}

References data, dhcp_packet::dhcphdr, dhcpopt_init(), dhcpopt_no_realloc(), dhcppkt_settings_operations, len, NULL, offsetof, dhcp_packet::options, options, dhcphdr::options, ref_init, dhcp_packet::refcnt, dhcp_packet::settings, and settings_init().

Referenced by cachedhcp_record(), dhcp_create_packet(), dhcp_deliver(), and efi_pxe_fake().

Variable Documentation

dhcp_packet_fields

struct dhcp_packet_field dhcp_packet_fields[]

static

Initial value:

= {
        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 ),
}

Dedicated fields within a DHCP packet.

Definition at line 103 of file dhcppkt.c.

Referenced by find_dhcp_packet_field().

dhcppkt_settings_operations

struct settings_operations dhcppkt_settings_operations

static

Initial value:

= {
        .applies = dhcppkt_settings_applies,
        .store = dhcppkt_settings_store,
        .fetch = dhcppkt_settings_fetch,
}

DHCP settings operations.

Definition at line 278 of file dhcppkt.c.

Referenced by dhcppkt_init().