A cache implementation for nanocoap response messages. More...

Detailed Description

A cache implementation for nanocoap response messages.

Files
file	cache.h
	nanocoap-cache API

Data Structures
struct	nanocoap_cache_entry_t
	Cache container that holds a `coap_pkt_t` struct. More...

Macros
#define	CONFIG_NANOCOAP_CACHE_ENTRIES (8)
	The number of maximum cache entries.

#define	CONFIG_NANOCOAP_CACHE_KEY_LENGTH (8)
	The length of the cache key in bytes.

#define	CONFIG_NANOCOAP_CACHE_RESPONSE_SIZE (128)
	Size of the buffer to store responses in the cache.

Typedefs
typedef int(*	nanocoap_cache_replacement_strategy_t) (void)
	Typedef for the cache replacement strategy on full cache list.

typedef int(*	nanocoap_cache_update_strategy_t) (clist_node_t *node)
	Typedef for the cache update strategy on element access.

Functions
static void	nanocoap_cache_init (void)
	Initializes the internal state of the nanocoap cache.

size_t	nanocoap_cache_used_count (void)
	Returns the number of cached entries.

size_t	nanocoap_cache_free_count (void)
	Returns the number of unused cache entries.

nanocoap_cache_entry_t *	nanocoap_cache_process (const uint8_t cache_key, unsigned request_method, const coap_pkt_t resp, size_t resp_len)
	Determines if a response is cacheable and modifies the cache as reflected in RFC7252, Section 5.9.

nanocoap_cache_entry_t *	nanocoap_cache_add_by_req (const coap_pkt_t req, const coap_pkt_t resp, size_t resp_len)
	Creates a new or gets an existing cache entry using the request packet.

nanocoap_cache_entry_t *	nanocoap_cache_add_by_key (const uint8_t cache_key, unsigned request_method, const coap_pkt_t resp, size_t resp_len)
	Creates a new or gets an existing cache entry using the cache key.

nanocoap_cache_entry_t *	nanocoap_cache_request_lookup (const coap_pkt_t *req)
	Performs a cache lookup based on the `req`.

nanocoap_cache_entry_t *	nanocoap_cache_key_lookup (const uint8_t *cache_key)
	Performs a cache lookup based on the cache key of a request.

int	nanocoap_cache_del (const nanocoap_cache_entry_t *ce)
	Deletes the provided cache entry `ce`.

void	nanocoap_cache_key_generate (const coap_pkt_t req, uint8_t cache_key)
	Generates a cache key based on the request `req`.

void	nanocoap_cache_key_options_generate (const coap_pkt_t req, void cache_key)
	Generates a cache key based on only the options in `req`.

void	nanocoap_cache_key_blockreq_options_generate (const coap_pkt_t req, void cache_key)
	Generates a cache key based on only the options in `req` without any of the blockwise options included in the key.

ssize_t	nanocoap_cache_key_compare (uint8_t cache_key1, uint8_t cache_key2)
	Compares two cache keys.

static bool	nanocoap_cache_entry_is_stale (const nanocoap_cache_entry_t *ce, uint32_t now)
	Check if the Max-Age of a cache entry has passed.

Macro Definition Documentation

◆ CONFIG_NANOCOAP_CACHE_ENTRIES

#define CONFIG_NANOCOAP_CACHE_ENTRIES (8)

The number of maximum cache entries.

Definition at line 41 of file cache.h.

◆ CONFIG_NANOCOAP_CACHE_KEY_LENGTH

#define CONFIG_NANOCOAP_CACHE_KEY_LENGTH (8)

The length of the cache key in bytes.

Definition at line 48 of file cache.h.

◆ CONFIG_NANOCOAP_CACHE_RESPONSE_SIZE

#define CONFIG_NANOCOAP_CACHE_RESPONSE_SIZE (128)

Size of the buffer to store responses in the cache.

Definition at line 55 of file cache.h.

Typedef Documentation

◆ nanocoap_cache_replacement_strategy_t

typedef int(* nanocoap_cache_replacement_strategy_t) (void)

Typedef for the cache replacement strategy on full cache list.

Returns: 0 on successfully replacing a cache element; -1 on error

Definition at line 102 of file cache.h.

◆ nanocoap_cache_update_strategy_t

typedef int(* nanocoap_cache_update_strategy_t) (clist_node_t *node)

Typedef for the cache update strategy on element access.

Parameters

[in] node The accessed node.

Returns: 0 on successfully updating the element; -1 on error

Definition at line 112 of file cache.h.

Function Documentation

◆ nanocoap_cache_add_by_key()

nanocoap_cache_entry_t * nanocoap_cache_add_by_key	(	const uint8_t *	cache_key,
		unsigned	request_method,
		const coap_pkt_t *	resp,
		size_t	resp_len
	)

Creates a new or gets an existing cache entry using the cache key.

Parameters

[in]	cache_key	The cache key of the request
[in]	request_method	The method of the initial request
[in]	resp	The response to add to the cache
[in]	resp_len	The actual length of the response in `resp`

Returns: The previously existing or newly added cache entry on success; NULL, if there is no space left

◆ nanocoap_cache_add_by_req()

nanocoap_cache_entry_t * nanocoap_cache_add_by_req	(	const coap_pkt_t *	req,
		const coap_pkt_t *	resp,
		size_t	resp_len
	)

Creates a new or gets an existing cache entry using the request packet.

Parameters

[in]	req	The request to calculate the cache-key
[in]	resp	The response to add to the cache
[in]	resp_len	The actual length of the response message in `resp`

Returns: The previously existing or newly added cache entry on success; NULL, if there is no space left

◆ nanocoap_cache_del()

int nanocoap_cache_del ( const nanocoap_cache_entry_t * ce )

Deletes the provided cache entry ce.

Parameters

[in] ce The cache entry to delete

Returns: 0 on success; -1 if entry is not available in the cache

◆ nanocoap_cache_entry_is_stale()

static bool nanocoap_cache_entry_is_stale	(	const nanocoap_cache_entry_t *	ce,
		uint32_t	now
	)

inlinestatic

Check if the Max-Age of a cache entry has passed.

Parameters

[in]	ce	A cache entry
[in]	now	The current time

Returns: true, if Max-Age of cache entry has passed.; false, if Max-Age of cache entry has not yet passed.

Definition at line 263 of file cache.h.

◆ nanocoap_cache_free_count()

size_t nanocoap_cache_free_count ( void )

Returns the number of unused cache entries.

Returns: Number of unused cache entries

◆ nanocoap_cache_init()

static void nanocoap_cache_init ( void )

inlinestatic

Initializes the internal state of the nanocoap cache.

Definition at line 120 of file cache.h.

◆ nanocoap_cache_key_blockreq_options_generate()

void nanocoap_cache_key_blockreq_options_generate	(	const coap_pkt_t *	req,
		void *	cache_key
	)

Generates a cache key based on only the options in req without any of the blockwise options included in the key.

This function can be used to correlate individual requests that are part of a blockwise transfer with each other.

Parameters

[in]	req	The request to generate the cache key from
[out]	cache_key	The generated cache key of SHA256_DIGEST_LENGTH bytes

◆ nanocoap_cache_key_compare()

ssize_t nanocoap_cache_key_compare	(	uint8_t *	cache_key1,
		uint8_t *	cache_key2
	)

Compares two cache keys.

Parameters

[in]	cache_key1	The first cache key in the comparison
[in]	cache_key2	The second cache key in the comparison

Returns: 0 if cache keys are equal; <0 or 0> (see memcmp()) for unequal cache keys

◆ nanocoap_cache_key_generate()

void nanocoap_cache_key_generate	(	const coap_pkt_t *	req,
		uint8_t *	cache_key
	)

Generates a cache key based on the request req.

Parameters

[in]	req	The request to generate the cache key from
[out]	cache_key	The generated cache key

◆ nanocoap_cache_key_lookup()

nanocoap_cache_entry_t * nanocoap_cache_key_lookup ( const uint8_t * cache_key )

Performs a cache lookup based on the cache key of a request.

Parameters

[in] cache_key The cache key of a request

Returns: An existing cache entry on cache hit; NULL on cache miss

◆ nanocoap_cache_key_options_generate()

void nanocoap_cache_key_options_generate	(	const coap_pkt_t *	req,
		void *	cache_key
	)

Generates a cache key based on only the options in req.

Parameters

[in]	req	The request to generate the cache key from
[out]	cache_key	The generated cache key of SHA256_DIGEST_LENGTH bytes

◆ nanocoap_cache_process()

nanocoap_cache_entry_t * nanocoap_cache_process	(	const uint8_t *	cache_key,
		unsigned	request_method,
		const coap_pkt_t *	resp,
		size_t	resp_len
	)

Determines if a response is cacheable and modifies the cache as reflected in RFC7252, Section 5.9.

Parameters

[in]	cache_key	The cache key of the request
[in]	request_method	The method of the initial request
[in]	resp	The response to operate on
[in]	resp_len	The actual length of the response in `resp`

Returns: The cache entry on successfully handling the response; NULL on error

◆ nanocoap_cache_request_lookup()

nanocoap_cache_entry_t * nanocoap_cache_request_lookup ( const coap_pkt_t * req )

Performs a cache lookup based on the req.

Parameters

[in] req The request to calculate the cache-key

Returns: An existing cache entry on cache hit; NULL on cache miss

◆ nanocoap_cache_used_count()

size_t nanocoap_cache_used_count ( void )

Returns the number of cached entries.

Returns: Number of cached entries

Detailed Description

Files

Data Structures

Macros

Typedefs

Functions

Macro Definition Documentation

◆ CONFIG_NANOCOAP_CACHE_ENTRIES

◆ CONFIG_NANOCOAP_CACHE_KEY_LENGTH

◆ CONFIG_NANOCOAP_CACHE_RESPONSE_SIZE

Typedef Documentation

◆ nanocoap_cache_replacement_strategy_t

◆ nanocoap_cache_update_strategy_t

Function Documentation

◆ nanocoap_cache_add_by_key()

◆ nanocoap_cache_add_by_req()

◆ nanocoap_cache_del()

◆ nanocoap_cache_entry_is_stale()

◆ nanocoap_cache_free_count()

◆ nanocoap_cache_init()

◆ nanocoap_cache_key_blockreq_options_generate()

◆ nanocoap_cache_key_compare()

◆ nanocoap_cache_key_generate()

◆ nanocoap_cache_key_lookup()

◆ nanocoap_cache_key_options_generate()

◆ nanocoap_cache_process()

◆ nanocoap_cache_request_lookup()

◆ nanocoap_cache_used_count()