1 /* 2 * Copyright (c) 2020 Nordic Semiconductor ASA 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #ifndef ZCBOR_DECODE_H__ 8 #define ZCBOR_DECODE_H__ 9 10 #include <stdint.h> 11 #include <stdbool.h> 12 #include <stddef.h> 13 #include "zcbor_common.h" 14 15 #ifdef __cplusplus 16 extern "C" { 17 #endif 18 19 /** The zcbor_decode library provides functions for decoding CBOR data elements. 20 * 21 * See The README for an introduction to CBOR, including the meaning of pint, 22 * nint, bstr etc. 23 */ 24 25 26 /** See @ref zcbor_new_state() */ 27 void zcbor_new_decode_state(zcbor_state_t *state_array, size_t n_states, 28 const uint8_t *payload, size_t payload_len, size_t elem_count, 29 uint8_t *elem_state, size_t elem_state_bytes); 30 31 /** Convenience macro for declaring and initializing a decoding state with backups. 32 * 33 * This gives you a state variable named @p name. The variable functions like 34 * a pointer. 35 * 36 * @param[in] name The name of the new state variable. 37 * @param[in] num_backups The number of backup slots to keep in the state. 38 * @param[in] payload The payload to work on. 39 * @param[in] payload_size The size (in bytes) of @p payload. 40 * @param[in] elem_count The starting elem_count (typically 1). 41 * @param[in] n_flags For use if ZCBOR_MAP_SMART_SEARCH is enabled, ignored otherwise. 42 * The total number of unordered map search flags needed. 43 * I.e. the largest number of elements expected in an unordered map, 44 * including elements in nested unordered maps. 45 */ 46 #define ZCBOR_STATE_D(name, num_backups, payload, payload_size, elem_count, n_flags) \ 47 zcbor_state_t name[((num_backups) + 2 + ZCBOR_FLAG_STATES(n_flags))]; \ 48 do { \ 49 zcbor_new_decode_state(name, ZCBOR_ARRAY_SIZE(name), payload, payload_size, elem_count, \ 50 (uint8_t *)&name[(num_backups) + 1], ZCBOR_FLAG_STATES(n_flags) * sizeof(zcbor_state_t)); \ 51 } while(0) 52 53 54 /** The following applies to all _decode() functions listed directly below. 55 * 56 * @param[inout] state The current state of the decoding. 57 * @param[out] result Where to place the decoded value. 58 * @param[in] result_size (if present) Size in bytes of the memory at @p result 59 * 60 * @retval true If the value was decoded correctly. 61 * @retval false If the value has the wrong type, the payload overflowed, the 62 * element count was exhausted, or the value was larger than can 63 * fit in the result variable. 64 * Use zcbor_peek_error() to see the error code. 65 */ 66 bool zcbor_int32_decode(zcbor_state_t *state, int32_t *result); /* pint/nint */ 67 bool zcbor_int64_decode(zcbor_state_t *state, int64_t *result); /* pint/nint */ 68 bool zcbor_uint32_decode(zcbor_state_t *state, uint32_t *result); /* pint */ 69 bool zcbor_uint64_decode(zcbor_state_t *state, uint64_t *result); /* pint */ 70 bool zcbor_size_decode(zcbor_state_t *state, size_t *result); /* pint */ 71 bool zcbor_int_decode(zcbor_state_t *state, void *result, size_t result_size); /* pint/nint */ 72 bool zcbor_uint_decode(zcbor_state_t *state, void *result, size_t result_size); /* pint */ 73 bool zcbor_bstr_decode(zcbor_state_t *state, struct zcbor_string *result); /* bstr */ 74 bool zcbor_tstr_decode(zcbor_state_t *state, struct zcbor_string *result); /* tstr */ 75 bool zcbor_tag_decode(zcbor_state_t *state, uint32_t *result); /* CBOR tag */ 76 bool zcbor_bool_decode(zcbor_state_t *state, bool *result); /* boolean CBOR simple value */ 77 bool zcbor_float16_decode(zcbor_state_t *state, float *result); /* IEEE754 float16 */ 78 bool zcbor_float16_bytes_decode(zcbor_state_t *state, uint16_t *result); /* IEEE754 float16 raw bytes */ 79 bool zcbor_float16_32_decode(zcbor_state_t *state, float *result); /* IEEE754 float16 or float32 */ 80 bool zcbor_float32_decode(zcbor_state_t *state, float *result); /* IEEE754 float32 */ 81 bool zcbor_float32_64_decode(zcbor_state_t *state, double *result); /* IEEE754 float32 or float64 */ 82 bool zcbor_float64_decode(zcbor_state_t *state, double *result); /* IEEE754 float64 */ 83 bool zcbor_float_decode(zcbor_state_t *state, double *result); /* IEEE754 float16, float32, or float64 */ 84 85 /** The following applies to all _expect() and _pexpect() functions listed directly below. 86 * 87 * @param[inout] state The current state of the decoding. 88 * @param[in] expected The expected value. 89 * 90 * @retval true If the result was decoded correctly and has the expected value. 91 * @retval false If the decoding failed or the result doesn't have the 92 * expected value. 93 * Use zcbor_peek_error() to see the error code. 94 */ 95 bool zcbor_int32_expect(zcbor_state_t *state, int32_t expected); /* pint/nint */ 96 bool zcbor_int64_expect(zcbor_state_t *state, int64_t expected); /* pint/nint */ 97 bool zcbor_uint32_expect(zcbor_state_t *state, uint32_t expected); /* pint */ 98 bool zcbor_uint64_expect(zcbor_state_t *state, uint64_t expected); /* pint */ 99 bool zcbor_size_expect(zcbor_state_t *state, size_t expected); /* pint */ 100 bool zcbor_bstr_expect(zcbor_state_t *state, struct zcbor_string *expected); /* bstr */ 101 bool zcbor_tstr_expect(zcbor_state_t *state, struct zcbor_string *expected); /* tstr */ 102 bool zcbor_tag_expect(zcbor_state_t *state, uint32_t expected); /* CBOR tag */ 103 bool zcbor_bool_expect(zcbor_state_t *state, bool expected); /* boolean CBOR simple value */ 104 bool zcbor_nil_expect(zcbor_state_t *state, void *unused); /* 'nil' CBOR simple value */ 105 bool zcbor_undefined_expect(zcbor_state_t *state, void *unused); /* 'undefined' CBOR simple value */ 106 bool zcbor_float16_expect(zcbor_state_t *state, float expected); /* IEEE754 float16 */ 107 bool zcbor_float16_bytes_expect(zcbor_state_t *state, uint16_t expected); /* IEEE754 float16 raw bytes */ 108 bool zcbor_float16_32_expect(zcbor_state_t *state, float expected); /* IEEE754 float16 or float32 */ 109 bool zcbor_float32_expect(zcbor_state_t *state, float expected); /* IEEE754 float32 */ 110 bool zcbor_float32_64_expect(zcbor_state_t *state, double expected); /* IEEE754 float32 or float64 */ 111 bool zcbor_float64_expect(zcbor_state_t *state, double expected); /* IEEE754 float64 */ 112 bool zcbor_float_expect(zcbor_state_t *state, double expected); /* IEEE754 float16, float32, or float64 */ 113 114 /** Like the _expect() functions but the value is passed through a pointer. 115 * (for use as a zcbor_decoder_t function) */ 116 bool zcbor_int32_pexpect(zcbor_state_t *state, int32_t *expected); /* pint/nint */ 117 bool zcbor_int64_pexpect(zcbor_state_t *state, int64_t *expected); /* pint/nint */ 118 bool zcbor_uint32_pexpect(zcbor_state_t *state, uint32_t *expected); /* pint */ 119 bool zcbor_uint64_pexpect(zcbor_state_t *state, uint64_t *expected); /* pint */ 120 bool zcbor_size_pexpect(zcbor_state_t *state, size_t *expected); /* pint */ 121 bool zcbor_tag_pexpect(zcbor_state_t *state, uint32_t *expected); /* CBOR tag */ 122 bool zcbor_bool_pexpect(zcbor_state_t *state, bool *expected); /* boolean CBOR simple value */ 123 bool zcbor_float16_pexpect(zcbor_state_t *state, float *expected); /* IEEE754 float16 */ 124 bool zcbor_float16_bytes_pexpect(zcbor_state_t *state, uint16_t *expected); /* IEEE754 float16 raw bytes */ 125 bool zcbor_float16_32_pexpect(zcbor_state_t *state, float *expected); /* IEEE754 float16 or float32 */ 126 bool zcbor_float32_pexpect(zcbor_state_t *state, float *expected); /* IEEE754 float32 */ 127 bool zcbor_float32_64_pexpect(zcbor_state_t *state, double *expected); /* IEEE754 float32 or float64 */ 128 bool zcbor_float64_pexpect(zcbor_state_t *state, double *expected); /* IEEE754 float64 */ 129 bool zcbor_float_pexpect(zcbor_state_t *state, double *expected); /* IEEE754 float16, float32, or float64 */ 130 131 /** Consume and expect a pint/nint with a certain value, within a union. 132 * 133 * Calls @ref zcbor_union_elem_code then @ref zcbor_[u]int[32|64]_expect. 134 */ 135 bool zcbor_int32_expect_union(zcbor_state_t *state, int32_t expected); 136 bool zcbor_int64_expect_union(zcbor_state_t *state, int64_t expected); 137 bool zcbor_uint32_expect_union(zcbor_state_t *state, uint32_t expected); 138 bool zcbor_uint64_expect_union(zcbor_state_t *state, uint64_t expected); 139 140 /** Decode and consume a list/map header. 141 * 142 * The contents of the list can be decoded via subsequent function calls. 143 * A state backup is created to keep track of the element count. 144 * Call @ref zcbor_list_end_decode / @ref zcbor_map_end_decode when done 145 * decoding the contents of the list/map 146 * 147 * @retval true Header decoded correctly 148 * @retval false Header decoded incorrectly, or backup failed. 149 */ 150 bool zcbor_list_start_decode(zcbor_state_t *state); 151 bool zcbor_map_start_decode(zcbor_state_t *state); 152 bool zcbor_unordered_map_start_decode(zcbor_state_t *state); 153 154 /** Search for a key in a map. 155 * 156 * The CBOR spec allows elements (key-value pairs) in maps to appear in any order. 157 * This function should be used when the order of elements is unknown. 158 * 159 * This must only be used while inside a map that has been entered via 160 * @ref zcbor_unordered_map_start_decode. Use @ref zcbor_unordered_map_end_decode 161 * when leaving the map. 162 * 163 * This function searches for keys. When this function returns successfully, 164 * the @p state is pointing to the value corresponding to the found key. 165 * Therefore, to be able to call this function again, the value must first be 166 * decoded or skipped. 167 * 168 * When searching unordered maps, the found elements must be kept track of. 169 * By default, this function automatically keeps track, which means it keeps a 170 * running count of the number of found elements, which is checked when exiting 171 * the map. You can do this manually instead, see @ref zcbor_elem_processed and 172 * @ref manually_process_elem. If ZCBOR_MAP_SMART_SEARCH is defined, a flag is 173 * kept for each element, instead of a rolling count. 174 * 175 * @note Unless ZCBOR_MAP_SMART_SEARCH is defined, 176 * elements are not individually marked as processed, so they may 177 * be returned again in a subsequent call to this function, if it is 178 * matched by the @p key_decoder of that call. Because of this, you should 179 * only use this function when you know the @p key_decoder matches no more 180 * than one of the keys. Typically this means all keys are known strings 181 * or integers, i.e. the @p key_decoder is typically a _pexpect() function. 182 * 183 * When searching for strings, there are convenience functions available, 184 * see the zcbor_search_key_* functions. 185 * 186 * @param[in] key_decoder A decoding function that will be tried against all 187 * keys in the map until it returns true, at which point 188 * @ref zcbor_unordered_map_search will return true. 189 * For example, a zcbor_*_pexpect() function. 190 * @param[inout] state The current state of decoding. Must be currently decoding 191 * the contents of a map, and pointing to one (any) of the 192 * keys, not one of the values. If successful, the @p state 193 * will be pointing to the value corresponding to the 194 * matched key. If unsuccessful, the @p state will be 195 * unchanged. 196 * @param[inout] key_result This will be passed as the second argument to the 197 * @p key_decoder. 198 * 199 * @retval true If the key was found, i.e. @p key_decoder returned true. 200 * @retval false If the key was not found after searching all map elements. 201 * Or the map was pointing to a value (not a key). 202 * Or an unexpected error happened while skipping elements or 203 * jumping from the end of the map to the start. 204 */ 205 bool zcbor_unordered_map_search(zcbor_decoder_t key_decoder, zcbor_state_t *state, void *key_result); 206 207 /** Find a specific bstr/tstr key as part of a map with unknown element order. 208 * 209 * Uses @ref zcbor_unordered_map_search under the hood. Please refer to those docs 210 * for the conditions under which this can be called. 211 * Refer to the docs for zcbor_(t|b)str_expect_* (e.g. @ref zcbor_bstr_expect_ptr) 212 * for parameter docs. 213 */ 214 bool zcbor_search_key_bstr_ptr(zcbor_state_t *state, char const *ptr, size_t len); 215 bool zcbor_search_key_tstr_ptr(zcbor_state_t *state, char const *ptr, size_t len); 216 bool zcbor_search_key_bstr_term(zcbor_state_t *state, char const *str, size_t maxlen); 217 bool zcbor_search_key_tstr_term(zcbor_state_t *state, char const *str, size_t maxlen); 218 #define zcbor_search_key_bstr_lit(state, str) zcbor_search_key_bstr_ptr(state, str, sizeof(str) - 1) 219 #define zcbor_search_key_tstr_lit(state, str) zcbor_search_key_tstr_ptr(state, str, sizeof(str) - 1) 220 #define zcbor_search_key_bstr_arr(state, str) zcbor_search_key_bstr_ptr(state, str, (sizeof(str))) 221 #define zcbor_search_key_tstr_arr(state, str) zcbor_search_key_tstr_ptr(state, str, (sizeof(str))) 222 223 /** (Optional) Call this function to mark an (unordered map) element as processed. 224 * 225 * @note This should not be called unless the @ref manually_process_elem flag is set. 226 * By default, i.e. when @ref manually_process_elem is not set, this function is 227 * called internally by @ref zcbor_unordered_map_search whenever a key is found. 228 * 229 * By default, this function increments the internal count @ref map_elems_processed. 230 * 231 * If ZCBOR_MAP_SMART_SEARCH is defined, this function instead clears a flag for the 232 * element (key-value pair) that is currently being processed, or that has just been 233 * processed, meaning the element won't be found again via @ref zcbor_unordered_map_search. 234 * 235 * @ref zcbor_unordered_map_end_decode will fail if @ref map_elems_processed does not 236 * match the number of elements in the map, or if any of the map element's flag is set. 237 */ 238 bool zcbor_elem_processed(zcbor_state_t *state); 239 240 /** Finalize decoding a list/map 241 * 242 * Check that the list/map had the correct number of elements, and restore the 243 * previous element count from the backup. 244 * 245 * Use @ref zcbor_list_map_end_force_decode to forcibly consume the backup if 246 * something has gone wrong. 247 * 248 * In all successful cases, the state is returned pointing to the byte/element 249 * after the list/map in the payload. 250 * 251 * @retval true Everything ok. 252 * @retval false Element count not correct. 253 */ 254 bool zcbor_list_end_decode(zcbor_state_t *state); 255 bool zcbor_map_end_decode(zcbor_state_t *state); 256 bool zcbor_unordered_map_end_decode(zcbor_state_t *state); 257 bool zcbor_list_map_end_force_decode(zcbor_state_t *state); 258 259 /** Find whether the state is at the end of a list or map. 260 */ 261 bool zcbor_array_at_end(zcbor_state_t *state); 262 263 /** Skip a single element, regardless of type and value. 264 * 265 * This means if the element is a map or list, this function will recursively 266 * skip all its contents. 267 * This function will also skip any tags preceeding the element. 268 * 269 * @param[inout] state The current state of the decoding. 270 * @param[in] unused Unused parameter to maintain signature parity with 271 * @ref zcbor_decoder_t. 272 */ 273 bool zcbor_any_skip(zcbor_state_t *state, void *unused); 274 275 /** Decode 0 or more elements with the same type and constraints. 276 * 277 * The decoded values will appear consecutively in the @p result array. 278 * 279 * The following is an example of decoding a list containing 3 INTS followed by 280 * 0 to 2 bstrs: 281 * 282 * @code{c} 283 * uint32_t ints[3]; 284 * struct zcbor_string bstrs[2]; 285 * uint32_t num_decode; 286 * bool res; 287 * 288 * res = zcbor_list_start_decode(state); 289 * res = res && zcbor_multi_decode(3, 3, &num_decode, zcbor_uint32_decode, 290 * state, ints, sizeof(ints[0])); 291 * res = res && zcbor_multi_decode(0, 2, &num_decode, zcbor_bstr_decode, 292 * state, bstrs, sizeof(bstrs[0])); 293 * res = res && zcbor_list_end_decode(state); 294 * // check res 295 * @endcode 296 * 297 * The @ref zcbor_decoder_t type is designed to be compatible with all single- 298 * value decoder functions in this library, e.g. @ref zcbor_uint32_decode, 299 * @ref zcbor_tstr_expect, @ref zcbor_nil_expect, etc. For _expect() functions, 300 * @p result will be used as a value instead of an array/pointer, so 301 * @p result_len will determine how much the value changes for each call. 302 * To decode the same value multiple times, use a @p result_len of 0. 303 * This function can also be used with custom decoder functions, such as those 304 * generated by the zcbor.py script, which for example decodes larger chunks of 305 * the data at once. 306 * 307 * @param[in] min_decode The minimum acceptable number of elements. 308 * @param[in] max_decode The maximum acceptable number of elements. 309 * @param[out] num_decode The actual number of elements decoded. 310 * @param[in] decoder The decoder function to call under the hood. This 311 * function will be called with the provided arguments 312 * repeatedly until the function fails (returns false) 313 * or until it has been called @p max_decode times. 314 * The result pointer is moved @p result_len bytes for 315 * each call to @p decoder, i.e. @p result refers to 316 * an array of result variables. 317 * Should not be an _expect() function, use 318 * _pexpect() instead. 319 * @param[out] result Where to place the decoded values. Must be an array 320 * of at least @p max_decode elements. 321 * @param[in] result_len The length of each result variable. Must be the 322 * length of the individual elements of @p result. 323 * 324 * @retval true If at least @p min_decode variables were correctly decoded. 325 * @retval false If @p decoder failed before having decoded @p min_decode 326 * values. 327 */ 328 bool zcbor_multi_decode(size_t min_decode, size_t max_decode, size_t *num_decode, 329 zcbor_decoder_t decoder, zcbor_state_t *state, void *result, 330 size_t result_len); 331 332 /** Attempt to decode a value that might not be present in the data. 333 * 334 * Works like @ref zcbor_multi_decode, with @p present as num_decode. 335 * Will return true, even if the data is not present. 336 * 337 * @param[out] present Whether or not the data was present and successfully decoded. 338 * @param[in] decoder The decoder to attempt. 339 * @param[out] result The result, if present. 340 * 341 * @return Should always return true. 342 */ 343 bool zcbor_present_decode(bool *present, 344 zcbor_decoder_t decoder, 345 zcbor_state_t *state, 346 void *result); 347 348 349 /** Supplementary string (bstr/tstr) decoding functions: */ 350 351 /** Consume and expect a bstr/tstr with the value of the provided char/uint8_t array. 352 * 353 * @param[inout] state The current state of the decoding. 354 * @param[in] str The value to expect. A pointer to the string/array. 355 * _term() uses strnlen(), so @p str must be null-terminated. 356 * _lit() uses sizeof()-1, so @p str must be a (null-terminated) string literal. 357 * _arr() uses sizeof(), so @p str must be a uint8_t array (not null-terminated). 358 * @param[in] len (if present) The length of the string pointed to by @p str 359 * @param[in] maxlen (if present) The maximum length of the string pointed to by @p str. 360 * This value is passed to strnlen. 361 */ 362 bool zcbor_bstr_expect_ptr(zcbor_state_t *state, char const *ptr, size_t len); 363 bool zcbor_tstr_expect_ptr(zcbor_state_t *state, char const *ptr, size_t len); 364 bool zcbor_bstr_expect_term(zcbor_state_t *state, char const *str, size_t maxlen); 365 bool zcbor_tstr_expect_term(zcbor_state_t *state, char const *str, size_t maxlen); 366 #define zcbor_bstr_expect_lit(state, str) zcbor_bstr_expect_ptr(state, str, sizeof(str) - 1) 367 #define zcbor_tstr_expect_lit(state, str) zcbor_tstr_expect_ptr(state, str, sizeof(str) - 1) 368 #define zcbor_bstr_expect_arr(state, str) zcbor_bstr_expect_ptr(state, str, sizeof(str)) 369 #define zcbor_tstr_expect_arr(state, str) zcbor_tstr_expect_ptr(state, str, sizeof(str)) 370 371 /** Decode and consume a bstr header. 372 * 373 * The rest of the string can be decoded as CBOR. 374 * A state backup is created to keep track of the element count. 375 * Call @ref zcbor_bstr_end_decode when done decoding the contents of the bstr. 376 * 377 * @param[inout] state The current state of the decoding. 378 * @param[out] result The resulting string, for reference. The string should be decoded via 379 * functions from this API since state is pointing to the start of the string, 380 * not the end. 381 * 382 * @retval true Header decoded correctly 383 * @retval false Header decoded incorrectly, or backup failed, or payload is not large enough 384 * to contain the contents of the string. Use @ref zcbor_bstr_start_decode_fragment 385 * for decoding fragmented payloads. 386 */ 387 bool zcbor_bstr_start_decode(zcbor_state_t *state, struct zcbor_string *result); 388 389 /** Finalize decoding a CBOR-encoded bstr. 390 * 391 * Restore element count from backup. 392 */ 393 bool zcbor_bstr_end_decode(zcbor_state_t *state); 394 395 396 /** Supplementary string (bstr/tstr) decoding functions for fragmented payloads: */ 397 398 /** Start decoding a bstr/tstr, even if the payload contains only part of it. 399 * 400 * This must be followed by a call to @ref zcbor_update_state, which can be 401 * followed by a call to @ref zcbor_next_fragment. Do not call this function 402 * again on subsequent fragments of the same string. 403 * 404 * This consumes the remaining payload as long as it belongs to the string. 405 */ 406 bool zcbor_bstr_decode_fragment(zcbor_state_t *state, struct zcbor_string_fragment *result); 407 bool zcbor_tstr_decode_fragment(zcbor_state_t *state, struct zcbor_string_fragment *result); 408 409 /** Extract the next fragment of a string. 410 * 411 * Use this function to extract all but the first fragment. 412 */ 413 void zcbor_next_fragment(zcbor_state_t *state, 414 struct zcbor_string_fragment *prev_fragment, 415 struct zcbor_string_fragment *result); 416 417 /** Decode and consume a bstr header, assuming the payload does not contain the whole bstr. 418 * 419 * The rest of the string can be decoded as CBOR. 420 * A state backup is created to keep track of the element count. 421 * Call @ref zcbor_update_state followed by @ref zcbor_bstr_next_fragment when 422 * the current payload has been exhausted. 423 * Call @ref zcbor_bstr_end_decode when done decoding the contents of the bstr. 424 */ 425 bool zcbor_bstr_start_decode_fragment(zcbor_state_t *state, 426 struct zcbor_string_fragment *result); 427 428 /** Start decoding the next fragment of a string. 429 * 430 * Use this function to extract all but the first fragment of a CBOR-encoded 431 * bstr. 432 */ 433 void zcbor_bstr_next_fragment(zcbor_state_t *state, 434 struct zcbor_string_fragment *prev_fragment, 435 struct zcbor_string_fragment *result); 436 437 /** Can be used on any fragment to tell if it is the final fragment of the string. */ 438 bool zcbor_is_last_fragment(const struct zcbor_string_fragment *fragment); 439 440 #ifdef __cplusplus 441 } 442 #endif 443 444 #endif /* ZCBOR_DECODE_H__ */ 445
