libcoap  4.3.1
coap_cache.c
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1 /* coap_cache.c -- Caching of CoAP requests
2 *
3 * Copyright (C) 2020 Olaf Bergmann <bergmann@tzi.org>
4 *
5  * SPDX-License-Identifier: BSD-2-Clause
6  *
7 * This file is part of the CoAP library libcoap. Please see
8 * README for terms of use.
9 */
10 
16 #include "coap3/coap_internal.h"
17 
18 #if COAP_SERVER_SUPPORT
19 /* Determines if the given option_type denotes an option type that can
20  * be used as CacheKey. Options that can be cache keys are not Unsafe
21  * and not marked explicitly as NoCacheKey. */
22 static int
23 is_cache_key(uint16_t option_type, size_t cache_ignore_count,
24  const uint16_t *cache_ignore_options) {
25  size_t i;
26 
27  /* https://tools.ietf.org/html/rfc7252#section-5.4.6 Nocachekey definition */
28  if ((option_type & 0x1e) == 0x1c)
29  return 0;
30  /*
31  * https://tools.ietf.org/html/rfc7641#section-2 Observe is not a
32  * part of the cache-key.
33  */
34  if (option_type == COAP_OPTION_OBSERVE)
35  return 0;
36 
37  /* Check for option user has defined as not part of cache-key */
38  for (i = 0; i < cache_ignore_count; i++) {
39  if (cache_ignore_options[i] == option_type) {
40  return 0;
41  }
42  }
43 
44  return 1;
45 }
46 
47 int
49  const uint16_t *options,
50  size_t count) {
51  if (ctx->cache_ignore_options) {
53  }
54  if (count) {
55  assert(options);
56  ctx->cache_ignore_options = coap_malloc(count * sizeof(options[0]));
57  if (ctx->cache_ignore_options) {
58  memcpy(ctx->cache_ignore_options, options, count * sizeof(options[0]));
59  ctx->cache_ignore_count = count;
60  }
61  else {
62  coap_log(LOG_WARNING, "Unable to create cache_ignore_options\n");
63  return 0;
64  }
65  }
66  else {
67  ctx->cache_ignore_options = NULL;
68  ctx->cache_ignore_count = count;
69  }
70  return 1;
71 }
72 
75  const coap_pdu_t *pdu,
76  coap_cache_session_based_t session_based,
77  const uint16_t *cache_ignore_options,
78  size_t cache_ignore_count) {
79  coap_opt_t *option;
80  coap_opt_iterator_t opt_iter;
81  coap_digest_ctx_t *dctx;
82  coap_digest_t digest;
83  coap_cache_key_t *cache_key;
84 
85  if (!coap_option_iterator_init(pdu, &opt_iter, COAP_OPT_ALL)) {
86  return NULL;
87  }
88 
89  dctx = coap_digest_setup();
90  if (!dctx)
91  return NULL;
92 
93  if (session_based == COAP_CACHE_IS_SESSION_BASED) {
94  /* Include the session ptr */
95  if (!coap_digest_update(dctx, (const uint8_t*)&session, sizeof(session))) {
96  goto update_fail;
97  }
98  }
99  while ((option = coap_option_next(&opt_iter))) {
100  if (is_cache_key(opt_iter.number, cache_ignore_count,
101  cache_ignore_options)) {
102  if (!coap_digest_update(dctx, (const uint8_t *)&opt_iter.number,
103  sizeof(opt_iter.number))) {
104  goto update_fail;
105  }
106  if (!coap_digest_update(dctx, coap_opt_value(option),
107  coap_opt_length(option))) {
108  goto update_fail;
109  }
110  }
111  }
112 
113  /* The body of a FETCH payload is part of the cache key,
114  * see https://tools.ietf.org/html/rfc8132#section-2 */
115  if (pdu->code == COAP_REQUEST_CODE_FETCH) {
116  size_t len;
117  const uint8_t *data;
118  if (coap_get_data(pdu, &len, &data)) {
119  if (!coap_digest_update(dctx, data, len)) {
120  goto update_fail;
121  }
122  }
123  }
124 
125  if (!coap_digest_final(dctx, &digest)) {
126  /* coap_digest_final() is guaranteed to free off dctx no matter what */
127  return NULL;
128  }
129  cache_key = coap_malloc_type(COAP_CACHE_KEY, sizeof(coap_cache_key_t));
130  if (cache_key) {
131  memcpy(cache_key->key, digest.key, sizeof(cache_key->key));
132  }
133  return cache_key;
134 update_fail:
135  coap_digest_free(dctx);
136  return NULL;
137 }
138 
141  const coap_pdu_t *pdu,
142  coap_cache_session_based_t session_based) {
143  return coap_cache_derive_key_w_ignore(session, pdu, session_based,
144  session->context->cache_ignore_options,
145  session->context->cache_ignore_count);
146 }
147 
148 void
150  coap_free_type(COAP_CACHE_KEY, cache_key);
151 }
152 
154 coap_new_cache_entry(coap_session_t *session, const coap_pdu_t *pdu,
155  coap_cache_record_pdu_t record_pdu,
156  coap_cache_session_based_t session_based,
157  unsigned int idle_timeout) {
159  sizeof(coap_cache_entry_t));
160  if (!entry) {
161  return NULL;
162  }
163 
164  memset(entry, 0, sizeof(coap_cache_entry_t));
165  entry->session = session;
166  if (record_pdu == COAP_CACHE_RECORD_PDU) {
167  entry->pdu = coap_pdu_init(pdu->type, pdu->code, pdu->mid, pdu->alloc_size);
168  if (entry->pdu) {
169  if (!coap_pdu_resize(entry->pdu, pdu->alloc_size)) {
170  coap_delete_pdu(entry->pdu);
172  return NULL;
173  }
174  /* Need to get the appropriate data across */
175  memcpy(entry->pdu, pdu, offsetof(coap_pdu_t, token));
176  memcpy(entry->pdu->token, pdu->token, pdu->used_size);
177  /* And adjust all the pointers etc. */
178  entry->pdu->data = entry->pdu->token + (pdu->data - pdu->token);
179  }
180  }
181  entry->cache_key = coap_cache_derive_key(session, pdu, session_based);
182  if (!entry->cache_key) {
184  return NULL;
185  }
186  entry->idle_timeout = idle_timeout;
187  if (idle_timeout > 0) {
188  coap_ticks(&entry->expire_ticks);
189  entry->expire_ticks += idle_timeout * COAP_TICKS_PER_SECOND;
190  }
191 
192  HASH_ADD(hh, session->context->cache, cache_key[0], sizeof(coap_cache_key_t), entry);
193  return entry;
194 }
195 
197 coap_cache_get_by_key(coap_context_t *ctx, const coap_cache_key_t *cache_key) {
198  coap_cache_entry_t *cache_entry = NULL;
199 
200  assert(cache_key);
201  if (cache_key) {
202  HASH_FIND(hh, ctx->cache, cache_key, sizeof(coap_cache_key_t), cache_entry);
203  }
204  if (cache_entry && cache_entry->idle_timeout > 0) {
205  coap_ticks(&cache_entry->expire_ticks);
206  cache_entry->expire_ticks += cache_entry->idle_timeout * COAP_TICKS_PER_SECOND;
207  }
208  return cache_entry;
209 }
210 
213  const coap_pdu_t *request,
214  coap_cache_session_based_t session_based) {
215  coap_cache_key_t *cache_key = coap_cache_derive_key(session, request, session_based);
216  coap_cache_entry_t *cache_entry;
217 
218  if (!cache_key)
219  return NULL;
220 
221  cache_entry = coap_cache_get_by_key(session->context, cache_key);
222  coap_delete_cache_key(cache_key);
223  if (cache_entry && cache_entry->idle_timeout > 0) {
224  coap_ticks(&cache_entry->expire_ticks);
225  cache_entry->expire_ticks += cache_entry->idle_timeout * COAP_TICKS_PER_SECOND;
226  }
227  return cache_entry;
228 }
229 
230 void
232 
233  assert(cache_entry);
234 
235  if (cache_entry) {
236  HASH_DELETE(hh, ctx->cache, cache_entry);
237  }
238  if (cache_entry->pdu) {
239  coap_delete_pdu(cache_entry->pdu);
240  }
241  coap_delete_cache_key(cache_entry->cache_key);
242  if (cache_entry->callback && cache_entry->app_data) {
243  cache_entry->callback(cache_entry->app_data);
244  }
245  coap_free_type(COAP_CACHE_ENTRY, cache_entry);
246 }
247 
248 const coap_pdu_t *
249 coap_cache_get_pdu(const coap_cache_entry_t *cache_entry) {
250  return cache_entry->pdu;
251 }
252 
253 void
255  void *data,
257  cache_entry->app_data = data;
258  cache_entry->callback = callback;
259 }
260 
261 void *
262 coap_cache_get_app_data(const coap_cache_entry_t *cache_entry) {
263  return cache_entry->app_data;
264 }
265 
266 void
268  coap_tick_t now;
269  coap_cache_entry_t *cp, *ctmp;
270 
271  coap_ticks(&now);
272  HASH_ITER(hh, ctx->cache, cp, ctmp) {
273  if (cp->idle_timeout > 0) {
274  if (cp->expire_ticks <= now) {
275  coap_delete_cache_entry(ctx, cp);
276  }
277  }
278  }
279 }
280 
281 #endif /* ! COAP_SERVER_SUPPORT */
Pulls together all the internal only header files.
uint8_t coap_opt_t
Use byte-oriented access methods here because sliding a complex struct coap_opt_t over the data buffe...
Definition: coap_option.h:26
void coap_digest_free(coap_digest_ctx_t *digest_ctx)
Free off coap_digest_ctx_t.
coap_digest_ctx_t * coap_digest_setup(void)
Initialize a coap_digest.
int coap_digest_final(coap_digest_ctx_t *digest_ctx, coap_digest_t *digest_buffer)
Finalize the coap_digest information into the provided digest_buffer.
int coap_digest_update(coap_digest_ctx_t *digest_ctx, const uint8_t *data, size_t data_len)
Update the coap_digest information with the next chunk of data.
void coap_digest_ctx_t
void coap_expire_cache_entries(coap_context_t *context)
Expire coap_cache_entry_t entries.
void coap_delete_cache_entry(coap_context_t *context, coap_cache_entry_t *cache_entry)
Remove a cache-entry from the hash list and free off all the appropriate contents apart from app_data...
coap_cache_entry_t * coap_cache_get_by_pdu(coap_session_t *session, const coap_pdu_t *pdu, coap_cache_session_based_t session_based)
Searches for a cache-entry corresponding to pdu.
const coap_pdu_t * coap_cache_get_pdu(const coap_cache_entry_t *cache_entry)
Returns the PDU information stored in the coap_cache entry.
void coap_delete_cache_key(coap_cache_key_t *cache_key)
Delete the cache-key.
coap_cache_record_pdu_t
Definition: coap_cache.h:42
coap_cache_key_t * coap_cache_derive_key_w_ignore(const coap_session_t *session, const coap_pdu_t *pdu, coap_cache_session_based_t session_based, const uint16_t *ignore_options, size_t ignore_count)
Calculates a cache-key for the given CoAP PDU.
void(* coap_cache_app_data_free_callback_t)(void *data)
Callback to free off the app data when the cache-entry is being deleted / freed off.
Definition: coap_cache.h:35
coap_cache_key_t * coap_cache_derive_key(const coap_session_t *session, const coap_pdu_t *pdu, coap_cache_session_based_t session_based)
Calculates a cache-key for the given CoAP PDU.
coap_cache_entry_t * coap_cache_get_by_key(coap_context_t *context, const coap_cache_key_t *cache_key)
Searches for a cache-entry identified by cache_key.
int coap_cache_ignore_options(coap_context_t *context, const uint16_t *options, size_t count)
Define the CoAP options that are not to be included when calculating the cache-key.
coap_cache_entry_t * coap_new_cache_entry(coap_session_t *session, const coap_pdu_t *pdu, coap_cache_record_pdu_t record_pdu, coap_cache_session_based_t session_based, unsigned int idle_time)
Create a new cache-entry hash keyed by cache-key derived from the PDU.
void * coap_cache_get_app_data(const coap_cache_entry_t *cache_entry)
Returns any application-specific data that has been stored with cache_entry using the function coap_c...
void coap_cache_set_app_data(coap_cache_entry_t *cache_entry, void *data, coap_cache_app_data_free_callback_t callback)
Stores data with the given cache entry.
coap_cache_session_based_t
Definition: coap_cache.h:37
@ COAP_CACHE_RECORD_PDU
Definition: coap_cache.h:44
@ COAP_CACHE_IS_SESSION_BASED
Definition: coap_cache.h:39
void coap_ticks(coap_tick_t *t)
Sets t to the internal time with COAP_TICKS_PER_SECOND resolution.
uint64_t coap_tick_t
This data type represents internal timer ticks with COAP_TICKS_PER_SECOND resolution.
Definition: coap_time.h:127
#define COAP_TICKS_PER_SECOND
Use ms resolution on POSIX systems.
Definition: coap_time.h:142
#define LOG_WARNING
Definition: coap_debug.h:72
#define coap_log(level,...)
Logging function.
Definition: coap_debug.h:165
coap_opt_t * coap_option_next(coap_opt_iterator_t *oi)
Updates the iterator oi to point to the next option.
Definition: coap_option.c:152
uint32_t coap_opt_length(const coap_opt_t *opt)
Returns the length of the given option.
Definition: coap_option.c:215
#define COAP_OPT_ALL
Pre-defined filter that includes all options.
Definition: coap_option.h:108
const uint8_t * coap_opt_value(const coap_opt_t *opt)
Returns a pointer to the value of the given option.
Definition: coap_option.c:252
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.
Definition: coap_option.c:116
int coap_pdu_resize(coap_pdu_t *pdu, size_t new_size)
Dynamically grows the size of pdu to new_size.
Definition: pdu.c:223
void coap_delete_pdu(coap_pdu_t *pdu)
Dispose of an CoAP PDU and frees associated storage.
Definition: pdu.c:154
int coap_get_data(const coap_pdu_t *pdu, size_t *len, const uint8_t **data)
Retrieves the length and data pointer of specified PDU.
Definition: pdu.c:713
#define COAP_OPTION_OBSERVE
Definition: pdu.h:115
coap_pdu_t * coap_pdu_init(coap_pdu_type_t type, coap_pdu_code_t code, coap_mid_t mid, size_t size)
Creates a new CoAP PDU with at least enough storage space for the given size maximum message size.
Definition: pdu.c:99
@ COAP_REQUEST_CODE_FETCH
Definition: pdu.h:310
void * coap_malloc_type(coap_memory_tag_t type, size_t size)
Allocates a chunk of size bytes and returns a pointer to the newly allocated memory.
COAP_STATIC_INLINE void * coap_malloc(size_t size)
Wrapper function to coap_malloc_type() for backwards compatibility.
Definition: mem.h:103
COAP_STATIC_INLINE void coap_free(void *object)
Wrapper function to coap_free_type() for backwards compatibility.
Definition: mem.h:110
@ COAP_CACHE_KEY
Definition: mem.h:53
@ COAP_CACHE_ENTRY
Definition: mem.h:54
void coap_free_type(coap_memory_tag_t type, void *p)
Releases the memory that was allocated by coap_malloc_type().
coap_session_t * session
coap_cache_app_data_free_callback_t callback
coap_tick_t expire_ticks
void * app_data
unsigned int idle_timeout
coap_cache_key_t * cache_key
coap_pdu_t * pdu
The CoAP stack's global state is stored in a coap_context_t object.
uint16_t * cache_ignore_options
CoAP options to ignore when creating a cache-key.
size_t cache_ignore_count
The number of CoAP options to ignore when creating a cache-key.
coap_cache_entry_t * cache
CoAP cache-entry cache.
Iterator to run through PDU options.
Definition: coap_option.h:171
coap_option_num_t number
decoded option number
Definition: coap_option.h:173
structure for CoAP PDUs
uint8_t * token
first byte of token, if any, or options
coap_pdu_code_t code
request method (value 1–31) or response code (value 64-255)
uint8_t * data
first byte of payload, if any
coap_mid_t mid
message id, if any, in regular host byte order
size_t used_size
used bytes of storage for token, options and payload
size_t alloc_size
allocated storage for token, options and payload
coap_pdu_type_t type
message type
Abstraction of virtual session that can be attached to coap_context_t (client) or coap_endpoint_t (se...
coap_context_t * context
session's context