Option Filters

API for access option filters. More...

Collaboration diagram for Option Filters:

Data Structures
struct	coap_opt_filter_t
struct	coap_opt_iterator_t
	Iterator to run through PDU options. More...
struct	coap_optlist_t
	Representation of chained list of CoAP options to install. More...

Macros
#define	COAP_OPT_FILTER_SHORT   6
	The number of option types below 256 that can be stored in an option filter.
#define	COAP_OPT_FILTER_LONG   2
	The number of option types above 255 that can be stored in an option filter.
#define	COAP_OPT_ALL   NULL
	Pre-defined filter that includes all options.

Typedefs
typedef struct coap_opt_filter_t	coap_opt_filter_t
typedef struct coap_optlist_t	coap_optlist_t
	Representation of chained list of CoAP options to install.

Functions
void	coap_option_filter_clear (coap_opt_filter_t *filter)
	Clears filter filter.
int	coap_option_filter_set (coap_opt_filter_t *filter, coap_option_num_t number)
	Sets the corresponding entry for number in filter.
int	coap_option_filter_unset (coap_opt_filter_t *filter, coap_option_num_t number)
	Clears the corresponding entry for number in filter.
int	coap_option_filter_get (coap_opt_filter_t *filter, coap_option_num_t number)
	Checks if number is contained in filter.
coap_opt_iterator_t *	coap_option_iterator_init (const coap_pdu_t *pdu, coap_opt_iterator_t *oi, const coap_opt_filter_t *filter)
	Initializes the given option iterator oi to point to the beginning of the pdu's option list.
coap_opt_t *	coap_option_next (coap_opt_iterator_t *oi)
	Updates the iterator oi to point to the next option.
coap_opt_t *	coap_check_option (const coap_pdu_t *pdu, coap_option_num_t number, coap_opt_iterator_t *oi)
	Retrieves the first option of number number from pdu.
size_t	coap_opt_setheader (coap_opt_t *opt, size_t maxlen, uint16_t delta, size_t length)
	Encodes the given delta and length values into opt.
size_t	coap_opt_encode_size (uint16_t delta, size_t length)
	Compute storage bytes needed for an option with given delta and length.
size_t	coap_opt_encode (coap_opt_t *opt, size_t n, uint16_t delta, const uint8_t *val, size_t length)
	Encodes option with given delta into opt.
uint32_t	coap_opt_length (const coap_opt_t *opt)
	Returns the length of the given option.
const uint8_t *	coap_opt_value (const coap_opt_t *opt)
	Returns a pointer to the value of the given option.
coap_optlist_t *	coap_new_optlist (uint16_t number, size_t length, const uint8_t *data)
	Create a new optlist entry.
int	coap_add_optlist_pdu (coap_pdu_t *pdu, coap_optlist_t **optlist_chain)
	The current optlist of optlist_chain is first sorted (as per RFC7272 ordering requirements) and then added to the pdu.
int	coap_insert_optlist (coap_optlist_t **optlist_chain, coap_optlist_t *optlist)
	Adds optlist to the given optlist_chain.
void	coap_delete_optlist (coap_optlist_t *optlist_chain)
	Removes all entries from the optlist_chain, freeing off their memory usage.

Detailed Description

API for access option filters.

Macro Definition Documentation

COAP_OPT_ALL

#define COAP_OPT_ALL   NULL

Pre-defined filter that includes all options.

Definition at line 108 of file coap_option.h.

COAP_OPT_FILTER_LONG

#define COAP_OPT_FILTER_LONG   2

The number of option types above 255 that can be stored in an option filter.

COAP_OPT_FILTER_SHORT + COAP_OPT_FILTER_LONG must be at most 16. Each coap_option_filter_t object reserves COAP_OPT_FILTER_LONG * 2 bytes for short options.

Definition at line 86 of file coap_option.h.

COAP_OPT_FILTER_SHORT

#define COAP_OPT_FILTER_SHORT   6

The number of option types below 256 that can be stored in an option filter.

COAP_OPT_FILTER_SHORT + COAP_OPT_FILTER_LONG must be at most 16. Each coap_option_filter_t object reserves ((COAP_OPT_FILTER_SHORT + 1) / 2) * 2 bytes for short options.

Definition at line 78 of file coap_option.h.

Typedef Documentation

coap_opt_filter_t

typedef struct coap_opt_filter_t coap_opt_filter_t

coap_optlist_t

typedef struct coap_optlist_t coap_optlist_t

Representation of chained list of CoAP options to install.

coap_optlist_t *optlist_chain = NULL;
coap_pdu_t *pdu = coap_new_pdu(session);
 
... other set up code ...
coap_insert_optlist(&optlist_chain, coap_new_optlist(COAP_OPTION_OBSERVE,
                   COAP_OBSERVE_ESTABLISH, NULL));
 
coap_add_optlist_pdu(pdu, &optlist_chain);
... other code ...
coap_delete_optlist(optlist_chain);

Function Documentation

coap_add_optlist_pdu()

int coap_add_optlist_pdu	(	coap_pdu_t *	pdu,
		coap_optlist_t **	optlist_chain
	)

The current optlist of optlist_chain is first sorted (as per RFC7272 ordering requirements) and then added to the pdu.

Parameters

pdu	The pdu to add the options to from the chain list
optlist_chain	The chained list of optlist to add to the pdu

Returns

1 if succesful or 0 if failure;

Definition at line 551 of file coap_option.c.

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coap_check_option()

coap_opt_t * coap_check_option	(	const coap_pdu_t *	pdu,
		coap_option_num_t	number,
		coap_opt_iterator_t *	oi
	)

Retrieves the first option of number number from pdu.

oi must point to a coap_opt_iterator_t object that will be initialized by this function to filter only options with number number. This function returns the first option with this number, or NULL if not found.

Parameters

pdu	The PDU to parse for options.
number	The option number to search for.
oi	An iterator object to use.

Returns

A pointer to the first option of number number, or NULL if not found.

Definition at line 199 of file coap_option.c.

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coap_delete_optlist()

void coap_delete_optlist

(

coap_optlist_t *

optlist_chain

)

Removes all entries from the optlist_chain, freeing off their memory usage.

Parameters

optlist_chain

The optlist chain to remove all the entries from

Definition at line 592 of file coap_option.c.

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coap_insert_optlist()

int coap_insert_optlist	(	coap_optlist_t **	optlist_chain,
		coap_optlist_t *	optlist
	)

Adds optlist to the given optlist_chain.

The optlist_chain variable be set to NULL before the initial call to coap_insert_optlist(). The optlist_chain will need to be deleted using coap_delete_optlist() when no longer required.

Parameters

optlist_chain	The chain to add optlist to
optlist	The optlist to add to the queue

Returns

1 if successful, 0 otherwise.

Definition at line 571 of file coap_option.c.

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coap_new_optlist()

coap_optlist_t * coap_new_optlist	(	uint16_t	number,
		size_t	length,
		const uint8_t *	data
	)

Create a new optlist entry.

Note: Where possible, the option data needs to be stripped of leading zeros (big endian) to reduce the amount of data needed in the PDU, as well as in some cases the maximum data size of an opton can be exceeded if not stripped and hence be illegal. This is done by using coap_encode_var_safe() or coap_encode_var_safe8().

Parameters

number	The option number (COAP_OPTION_*)
length	The option length
data	The option value data

Returns

A pointer to the new optlist entry, or NULL if error

Definition at line 511 of file coap_option.c.

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coap_opt_encode()

size_t coap_opt_encode	(	coap_opt_t *	opt,
		size_t	n,
		uint16_t	delta,
		const uint8_t *	val,
		size_t	length
	)

Encodes option with given delta into opt.

This function returns the number of bytes written to opt or 0 on error. This happens especially when opt does not provide sufficient space to store the option value, delta, and option jumps when required.

Parameters

opt	The option buffer space where val is written.
n	Maximum length of opt.
delta	The option delta.
val	The option value to copy into opt.
length	The actual length of val.

Returns

The number of bytes that have been written to opt or 0 on error. The return value will always be less than n.

Definition at line 372 of file coap_option.c.

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coap_opt_encode_size()

size_t coap_opt_encode_size	(	uint16_t	delta,
		size_t	length
	)

Compute storage bytes needed for an option with given delta and length.

Parameters

delta	The option delta.
length	The option length.

Returns

The number of bytes required to encode this option.

Definition at line 351 of file coap_option.c.

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coap_opt_length()

uint32_t coap_opt_length

(

const coap_opt_t *

opt

)

Returns the length of the given option.

opt must point to an option jump or the beginning of the option. This function returns 0 when opt is not an option or the actual length of opt (which can be 0 as well).

Note

{The rationale for using 0 in case of an error is that in most contexts, the result of this function is used to skip the next coap_opt_length() bytes.}

Parameters

opt	The option whose length should be returned.

Returns

The option's length or 0 when undefined.

Definition at line 212 of file coap_option.c.

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coap_opt_setheader()

size_t coap_opt_setheader	(	coap_opt_t *	opt,
		size_t	maxlen,
		uint16_t	delta,
		size_t	length
	)

Encodes the given delta and length values into opt.

This function returns the number of bytes that were required to encode delta and length or 0 on error. Note that the result indicates by how many bytes opt must be advanced to encode the option value.

Parameters

opt	The option buffer space where delta and length are written.
maxlen	The maximum length of opt.
delta	The actual delta value to encode.
length	The actual length value to encode.

Returns

The number of bytes used or 0 on error.

Definition at line 292 of file coap_option.c.

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coap_opt_value()

const uint8_t * coap_opt_value

(

const coap_opt_t *

opt

)

Returns a pointer to the value of the given option.

opt must point to an option jump or the beginning of the option. This function returns NULL if opt is not a valid option.

Parameters

opt	The option whose value should be returned.

Returns

A pointer to the option value or NULL on error.

Definition at line 249 of file coap_option.c.

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coap_option_filter_clear()

void coap_option_filter_clear

(

coap_opt_filter_t *

filter

)

Clears filter filter.

Parameters

filter

The filter to clear.

Definition at line 491 of file coap_option.c.

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coap_option_filter_get()

int coap_option_filter_get	(	coap_opt_filter_t *	filter,
		coap_option_num_t	number
	)

Checks if number is contained in filter.

This function returns 1 if found, 0 if not.

Parameters

filter	The filter object to search.
number	The option number to search for.

Returns

1 if number was found, 0 otherwise

Definition at line 506 of file coap_option.c.

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coap_option_filter_set()

int coap_option_filter_set	(	coap_opt_filter_t *	filter,
		coap_option_num_t	number
	)

Sets the corresponding entry for number in filter.

This function returns 1 if bit was set or 0 on error (i.e. when there is not enough space to fit the given number in the filter).

Parameters

filter	The filter object to change.
number	The option number for which the bit should be set.

Returns

1 if bit was set, 0 otherwise.

Definition at line 496 of file coap_option.c.

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coap_option_filter_unset()

int coap_option_filter_unset	(	coap_opt_filter_t *	filter,
		coap_option_num_t	number
	)

Clears the corresponding entry for number in filter.

This function returns 1 if bit was set or 0 if not previously set.

Parameters

filter	The filter object to change.
number	The option number that should be cleared from the filter.

Returns

1 if bit was cleared, 0 otherwise.

Definition at line 501 of file coap_option.c.

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coap_option_iterator_init()

coap_opt_iterator_t * coap_option_iterator_init	(	const coap_pdu_t *	pdu,
		coap_opt_iterator_t *	oi,
		const coap_opt_filter_t *	filter
	)

Initializes the given option iterator oi to point to the beginning of the pdu's option list.

This function returns oi on success, NULL otherwise (i.e. when no options exist). Note that a length check on the option list must be performed before coap_option_iterator_init() is called.

Parameters

pdu	The PDU the options of which should be walked through.
oi	An iterator object that will be initilized.
filter	An optional option number filter. With number != COAP_OPT_ALL, coap_option_next() will return only options matching this bitmask. Fence-post options 14, 28, 42, ... are always skipped.

Returns

The iterator object oi on success, NULL otherwise.

Definition at line 117 of file coap_option.c.

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coap_option_next()

coap_opt_t * coap_option_next

(

coap_opt_iterator_t *

oi

)

Updates the iterator oi to point to the next option.

This function returns a pointer to that option or NULL if no more options exist. The contents of oi will be updated. In particular, oi->n specifies the current option's ordinal number (counted from 1), oi->number is the option's number value, and oi->option points to the beginning of the current option itself. When * advanced past the last option, oi->option will be NULL.

Note that options are skipped whose corresponding bits in the filter specified with coap_option_iterator_init() are 0. Options with numbers that do not fit in this filter hence will always be returned.

Parameters

oi	The option iterator to update.

Returns

The next option or NULL if no more options exist.

Definition at line 153 of file coap_option.c.

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