dhcpopts.h File Reference

DHCP options. More...

#include <stdint.h>

Go to the source code of this file.

Data Structures
struct	dhcp_options
	A DHCP options block. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
int	dhcpopt_applies (unsigned int tag)
	Check applicability of DHCP option setting. More...
int	dhcpopt_store (struct dhcp_options *options, unsigned int tag, const void *data, size_t len)
	Store value of DHCP option setting. More...
int	dhcpopt_fetch (struct dhcp_options *options, unsigned int tag, void *data, size_t len)
	Fetch value of DHCP option setting. More...
void	dhcpopt_init (struct dhcp_options *options, void *data, size_t alloc_len, int(*realloc)(struct dhcp_options *options, size_t len))
	Initialise prepopulated block of DHCP options. More...
void	dhcpopt_update_used_len (struct dhcp_options *options)
	Recalculate length of DHCP options block. More...
int	dhcpopt_no_realloc (struct dhcp_options *options, size_t len)
	Refuse to reallocate DHCP option block. More...

Detailed Description

DHCP options.

Definition in file dhcpopts.h.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

dhcpopt_applies()

int dhcpopt_applies

(

unsigned int

tag

)

Check applicability of DHCP option setting.

Parameters

tag	Setting tag number

Return values

applies

Setting applies to this option block

Definition at line 359 of file dhcpopts.c.

                                         {

        return ( tag && ( tag <= DHCP_ENCAP_OPT ( DHCP_MAX_OPTION,
                                                  DHCP_MAX_OPTION ) ) );
}

References DHCP_ENCAP_OPT, DHCP_MAX_OPTION, and tag.

Referenced by dhcppkt_applies(), and nvo_applies().

dhcpopt_store()

int dhcpopt_store	(	struct dhcp_options *	options,
		unsigned int	tag,
		const void *	data,
		size_t	len
	)

Store value of DHCP option setting.

Parameters

options	DHCP option block
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 374 of file dhcpopts.c.

                                                   {
        int offset;

        offset = set_dhcp_option ( options, tag, data, len );
        if ( offset < 0 )
                return offset;
        return 0;
}

References data, len, offset, options, set_dhcp_option(), and tag.

Referenced by dhcppkt_store(), and nvo_store().

dhcpopt_fetch()

int dhcpopt_fetch	(	struct dhcp_options *	options,
		unsigned int	tag,
		void *	data,
		size_t	len
	)

Fetch value of DHCP option setting.

Parameters

options	DHCP option block
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 393 of file dhcpopts.c.

                                             {
        int offset;
        struct dhcp_option *option;
        size_t option_len;

        offset = find_dhcp_option_with_encap ( options, tag, NULL );
        if ( offset < 0 )
                return offset;

        option = dhcp_option ( options, offset );
        option_len = option->len;
        if ( len > option_len )
                len = option_len;
        memcpy ( data, option->data, len );

        return option_len;
}

References data, dhcp_option(), find_dhcp_option_with_encap(), len, memcpy(), NULL, offset, options, and tag.

Referenced by dhcppkt_fetch(), and nvo_fetch().

dhcpopt_init()

void dhcpopt_init	(	struct dhcp_options *	options,
		void *	data,
		size_t	alloc_len,
		int(*)(struct dhcp_options *options, size_t len)	realloc
	)

Initialise prepopulated block of DHCP options.

Parameters

options	Uninitialised DHCP option block
data	Memory for DHCP option data
alloc_len	Length of memory for DHCP option data
realloc	DHCP option block reallocator

The memory content must already be filled with valid DHCP options. A zeroed block counts as a block of valid DHCP options.

Definition at line 451 of file dhcpopts.c.

                                                       {

        /* Fill in fields */
        options->data = data;
        options->alloc_len = alloc_len;
        options->realloc = realloc;

        /* Update length */
        dhcpopt_update_used_len ( options );

        DBGC ( options, "DHCPOPT %p created (data %p lengths %#zx,%#zx)\n",
               options, options->data, options->used_len, options->alloc_len );
}

References data, DBGC, dhcpopt_update_used_len(), options, and realloc().

Referenced by dhcppkt_init(), and nvo_init().

dhcpopt_update_used_len()

void dhcpopt_update_used_len

(

struct dhcp_options *

options

)

Recalculate length of DHCP options block.

Parameters

options

Uninitialised DHCP option block

The "used length" field will be updated based on scanning through the block to find the end of the options.

Definition at line 420 of file dhcpopts.c.

                                                              {
        struct dhcp_option *option;
        int offset = 0;
        ssize_t remaining = options->alloc_len;
        unsigned int option_len;

        /* Find last non-pad option */
        options->used_len = 0;
        while ( remaining ) {
                option = dhcp_option ( options, offset );
                option_len = dhcp_option_len ( option );
                remaining -= option_len;
                if ( remaining < 0 )
                        break;
                offset += option_len;
                if ( option->tag != DHCP_PAD )
                        options->used_len = offset;
        }
}

References dhcp_option(), dhcp_option_len(), DHCP_PAD, offset, and options.

Referenced by dhcpopt_init(), and nvo_load().

dhcpopt_no_realloc()

int dhcpopt_no_realloc	(	struct dhcp_options *	options,
		size_t	len
	)

Refuse to reallocate DHCP option block.

Parameters

options	DHCP option block
len	New length

Return values

rc	Return status code

Definition at line 184 of file dhcpopts.c.

                                                                    {
        return ( ( len <= options->alloc_len ) ? 0 : -ENOSPC );
}

References ENOSPC.

Referenced by dhcppkt_init(), and nvo_realloc_dhcpopt().