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[proxmark3-svn] / client / tinycbor / cborparser.c
1 /****************************************************************************
2 **
3 ** Copyright (C) 2017 Intel Corporation
4 **
5 ** Permission is hereby granted, free of charge, to any person obtaining a copy
6 ** of this software and associated documentation files (the "Software"), to deal
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9 ** copies of the Software, and to permit persons to whom the Software is
10 ** furnished to do so, subject to the following conditions:
11 **
12 ** The above copyright notice and this permission notice shall be included in
13 ** all copies or substantial portions of the Software.
14 **
15 ** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 ** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 ** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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21 ** THE SOFTWARE.
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24
25 #ifndef _BSD_SOURCE
26 #define _BSD_SOURCE 1
27 #endif
28 #ifndef _DEFAULT_SOURCE
29 #define _DEFAULT_SOURCE 1
30 #endif
31 #ifndef __STDC_LIMIT_MACROS
32 # define __STDC_LIMIT_MACROS 1
33 #endif
34
35 #include "cbor.h"
36 #include "cborinternal_p.h"
37 #include "compilersupport_p.h"
38
39 #include <string.h>
40
41 /**
42 * \defgroup CborParsing Parsing CBOR streams
43 * \brief Group of functions used to parse CBOR streams.
44 *
45 * TinyCBOR provides functions for pull-based stream parsing of a CBOR-encoded
46 * payload. The main data type for the parsing is a CborValue, which behaves
47 * like an iterator and can be used to extract the encoded data. It is first
48 * initialized with a call to cbor_parser_init() and is usually used to extract
49 * exactly one item, most often an array or map.
50 *
51 * Nested CborValue objects can be parsed using cbor_value_enter_container().
52 * Each call to cbor_value_enter_container() must be matched by a call to
53 * cbor_value_leave_container(), with the exact same parameters.
54 *
55 * The example below initializes a CborParser object, begins the parsing with a
56 * CborValue and decodes a single integer:
57 *
58 * \code
59 * int extract_int(const uint8_t *buffer, size_t len)
60 * {
61 * CborParser parser;
62 * CborValue value;
63 * int result;
64 * cbor_parser_init(buffer, len, 0, &parser, &value);
65 * cbor_value_get_int(&value, &result);
66 * return result;
67 * }
68 * \endcode
69 *
70 * The code above does no error checking, which means it assumes the data comes
71 * from a source trusted to send one properly-encoded integer. The following
72 * example does the exact same operation, but includes error checking and
73 * returns 0 on parsing failure:
74 *
75 * \code
76 * int extract_int(const uint8_t *buffer, size_t len)
77 * {
78 * CborParser parser;
79 * CborValue value;
80 * int result;
81 * if (cbor_parser_init(buffer, len, 0, &parser, &value) != CborNoError)
82 * return 0;
83 * if (!cbor_value_is_integer(&value) ||
84 * cbor_value_get_int(&value, &result) != CborNoError)
85 * return 0;
86 * return result;
87 * }
88 * \endcode
89 *
90 * Note, in the example above, that one can't distinguish a parsing failure
91 * from an encoded value of zero. Reporting a parsing error is left as an
92 * exercise to the reader.
93 *
94 * The code above does not execute a range-check either: it is possible that
95 * the value decoded from the CBOR stream encodes a number larger than what can
96 * be represented in a variable of type \c{int}. If detecting that case is
97 * important, the code should call cbor_value_get_int_checked() instead.
98 *
99 * <h3 class="groupheader">Memory and parsing constraints</h3>
100 *
101 * TinyCBOR is designed to run with little memory and with minimal overhead.
102 * Except where otherwise noted, the parser functions always run on constant
103 * time (O(1)), do not recurse and never allocate memory (thus, stack usage is
104 * bounded and is O(1)).
105 *
106 * <h3 class="groupheader">Error handling and preconditions</h3>
107 *
108 * All functions operating on a CborValue return a CborError condition, with
109 * CborNoError standing for the normal situation in which no parsing error
110 * occurred. All functions may return parsing errors in case the stream cannot
111 * be decoded properly, be it due to corrupted data or due to reaching the end
112 * of the input buffer.
113 *
114 * Error conditions must not be ignored. All decoder functions have undefined
115 * behavior if called after an error has been reported, and may crash.
116 *
117 * Some functions are also documented to have preconditions, like
118 * cbor_value_get_int() requiring that the input be an integral value.
119 * Violation of preconditions also results in undefined behavior and the
120 * program may crash.
121 */
122
123 /**
124 * \addtogroup CborParsing
125 * @{
126 */
127
128 /**
129 * \struct CborValue
130 *
131 * This type contains one value parsed from the CBOR stream. Each CborValue
132 * behaves as an iterator in a StAX-style parser.
133 *
134 * \if privatedocs
135 * Implementation details: the CborValue contains these fields:
136 * \list
137 * \li ptr: pointer to the actual data
138 * \li flags: flags from the decoder
139 * \li extra: partially decoded integer value (0, 1 or 2 bytes)
140 * \li remaining: remaining items in this collection after this item or UINT32_MAX if length is unknown
141 * \endlist
142 * \endif
143 */
144
145 static inline uint16_t get16(const uint8_t *ptr)
146 {
147 uint16_t result;
148 memcpy(&result, ptr, sizeof(result));
149 return cbor_ntohs(result);
150 }
151
152 static inline uint32_t get32(const uint8_t *ptr)
153 {
154 uint32_t result;
155 memcpy(&result, ptr, sizeof(result));
156 return cbor_ntohl(result);
157 }
158
159 static inline uint64_t get64(const uint8_t *ptr)
160 {
161 uint64_t result;
162 memcpy(&result, ptr, sizeof(result));
163 return cbor_ntohll(result);
164 }
165
166 CborError CBOR_INTERNAL_API_CC _cbor_value_extract_number(const uint8_t **ptr, const uint8_t *end, uint64_t *len)
167 {
168 size_t bytesNeeded;
169 uint8_t additional_information = **ptr & SmallValueMask;
170 ++*ptr;
171 if (additional_information < Value8Bit) {
172 *len = additional_information;
173 return CborNoError;
174 }
175 if (unlikely(additional_information > Value64Bit))
176 return CborErrorIllegalNumber;
177
178 bytesNeeded = (size_t)(1 << (additional_information - Value8Bit));
179 if (unlikely(bytesNeeded > (size_t)(end - *ptr))) {
180 return CborErrorUnexpectedEOF;
181 } else if (bytesNeeded == 1) {
182 *len = (uint8_t)(*ptr)[0];
183 } else if (bytesNeeded == 2) {
184 *len = get16(*ptr);
185 } else if (bytesNeeded == 4) {
186 *len = get32(*ptr);
187 } else {
188 *len = get64(*ptr);
189 }
190 *ptr += bytesNeeded;
191 return CborNoError;
192 }
193
194 static CborError extract_length(const CborParser *parser, const uint8_t **ptr, size_t *len)
195 {
196 uint64_t v;
197 CborError err = _cbor_value_extract_number(ptr, parser->end, &v);
198 if (err) {
199 *len = 0;
200 return err;
201 }
202
203 *len = (size_t)v;
204 if (v != *len)
205 return CborErrorDataTooLarge;
206 return CborNoError;
207 }
208
209 static bool is_fixed_type(uint8_t type)
210 {
211 return type != CborTextStringType && type != CborByteStringType && type != CborArrayType &&
212 type != CborMapType;
213 }
214
215 static CborError preparse_value(CborValue *it)
216 {
217 const CborParser *parser = it->parser;
218 it->type = CborInvalidType;
219
220 /* are we at the end? */
221 if (it->ptr == parser->end)
222 return CborErrorUnexpectedEOF;
223
224 uint8_t descriptor = *it->ptr;
225 uint8_t type = descriptor & MajorTypeMask;
226 it->type = type;
227 it->flags = 0;
228 it->extra = (descriptor &= SmallValueMask);
229
230 if (descriptor > Value64Bit) {
231 if (unlikely(descriptor != IndefiniteLength))
232 return type == CborSimpleType ? CborErrorUnknownType : CborErrorIllegalNumber;
233 if (likely(!is_fixed_type(type))) {
234 /* special case */
235 it->flags |= CborIteratorFlag_UnknownLength;
236 it->type = type;
237 return CborNoError;
238 }
239 return type == CborSimpleType ? CborErrorUnexpectedBreak : CborErrorIllegalNumber;
240 }
241
242 size_t bytesNeeded = descriptor < Value8Bit ? 0 : (1 << (descriptor - Value8Bit));
243 if (bytesNeeded + 1 > (size_t)(parser->end - it->ptr))
244 return CborErrorUnexpectedEOF;
245
246 uint8_t majortype = type >> MajorTypeShift;
247 if (majortype == NegativeIntegerType) {
248 it->flags |= CborIteratorFlag_NegativeInteger;
249 it->type = CborIntegerType;
250 } else if (majortype == SimpleTypesType) {
251 switch (descriptor) {
252 case FalseValue:
253 it->extra = false;
254 it->type = CborBooleanType;
255 break;
256
257 case SinglePrecisionFloat:
258 case DoublePrecisionFloat:
259 it->flags |= CborIteratorFlag_IntegerValueTooLarge;
260 /* fall through */
261 case TrueValue:
262 case NullValue:
263 case UndefinedValue:
264 case HalfPrecisionFloat:
265 it->type = *it->ptr;
266 break;
267
268 case SimpleTypeInNextByte:
269 it->extra = (uint8_t)it->ptr[1];
270 #ifndef CBOR_PARSER_NO_STRICT_CHECKS
271 if (unlikely(it->extra < 32)) {
272 it->type = CborInvalidType;
273 return CborErrorIllegalSimpleType;
274 }
275 #endif
276 break;
277
278 case 28:
279 case 29:
280 case 30:
281 case Break:
282 cbor_assert(false); /* these conditions can't be reached */
283 return CborErrorUnexpectedBreak;
284 }
285 return CborNoError;
286 }
287
288 /* try to decode up to 16 bits */
289 if (descriptor < Value8Bit)
290 return CborNoError;
291
292 if (descriptor == Value8Bit)
293 it->extra = (uint8_t)it->ptr[1];
294 else if (descriptor == Value16Bit)
295 it->extra = get16(it->ptr + 1);
296 else
297 it->flags |= CborIteratorFlag_IntegerValueTooLarge; /* Value32Bit or Value64Bit */
298 return CborNoError;
299 }
300
301 static CborError preparse_next_value_nodecrement(CborValue *it)
302 {
303 if (it->remaining == UINT32_MAX && it->ptr != it->parser->end && *it->ptr == (uint8_t)BreakByte) {
304 /* end of map or array */
305 ++it->ptr;
306 it->type = CborInvalidType;
307 it->remaining = 0;
308 return CborNoError;
309 }
310
311 return preparse_value(it);
312 }
313
314 static CborError preparse_next_value(CborValue *it)
315 {
316 if (it->remaining != UINT32_MAX) {
317 /* don't decrement the item count if the current item is tag: they don't count */
318 if (it->type != CborTagType && --it->remaining == 0) {
319 it->type = CborInvalidType;
320 return CborNoError;
321 }
322 }
323 return preparse_next_value_nodecrement(it);
324 }
325
326 static CborError advance_internal(CborValue *it)
327 {
328 uint64_t length;
329 CborError err = _cbor_value_extract_number(&it->ptr, it->parser->end, &length);
330 cbor_assert(err == CborNoError);
331
332 if (it->type == CborByteStringType || it->type == CborTextStringType) {
333 cbor_assert(length == (size_t)length);
334 cbor_assert((it->flags & CborIteratorFlag_UnknownLength) == 0);
335 it->ptr += length;
336 }
337
338 return preparse_next_value(it);
339 }
340
341 /** \internal
342 *
343 * Decodes the CBOR integer value when it is larger than the 16 bits available
344 * in value->extra. This function requires that value->flags have the
345 * CborIteratorFlag_IntegerValueTooLarge flag set.
346 *
347 * This function is also used to extract single- and double-precision floating
348 * point values (SinglePrecisionFloat == Value32Bit and DoublePrecisionFloat ==
349 * Value64Bit).
350 */
351 uint64_t _cbor_value_decode_int64_internal(const CborValue *value)
352 {
353 cbor_assert(value->flags & CborIteratorFlag_IntegerValueTooLarge ||
354 value->type == CborFloatType || value->type == CborDoubleType);
355
356 /* since the additional information can only be Value32Bit or Value64Bit,
357 * we just need to test for the one bit those two options differ */
358 cbor_assert((*value->ptr & SmallValueMask) == Value32Bit || (*value->ptr & SmallValueMask) == Value64Bit);
359 if ((*value->ptr & 1) == (Value32Bit & 1))
360 return get32(value->ptr + 1);
361
362 cbor_assert((*value->ptr & SmallValueMask) == Value64Bit);
363 return get64(value->ptr + 1);
364 }
365
366 /**
367 * Initializes the CBOR parser for parsing \a size bytes beginning at \a
368 * buffer. Parsing will use flags set in \a flags. The iterator to the first
369 * element is returned in \a it.
370 *
371 * The \a parser structure needs to remain valid throughout the decoding
372 * process. It is not thread-safe to share one CborParser among multiple
373 * threads iterating at the same time, but the object can be copied so multiple
374 * threads can iterate.
375 */
376 CborError cbor_parser_init(const uint8_t *buffer, size_t size, uint32_t flags, CborParser *parser, CborValue *it)
377 {
378 memset(parser, 0, sizeof(*parser));
379 parser->end = buffer + size;
380 parser->flags = flags;
381 it->parser = parser;
382 it->ptr = buffer;
383 it->remaining = 1; /* there's one type altogether, usually an array or map */
384 return preparse_value(it);
385 }
386
387 /**
388 * \fn bool cbor_value_at_end(const CborValue *it)
389 *
390 * Returns true if \a it has reached the end of the iteration, usually when
391 * advancing after the last item in an array or map.
392 *
393 * In the case of the outermost CborValue object, this function returns true
394 * after decoding a single element. A pointer to the first byte of the
395 * remaining data (if any) can be obtained with cbor_value_get_next_byte().
396 *
397 * \sa cbor_value_advance(), cbor_value_is_valid(), cbor_value_get_next_byte()
398 */
399
400 /**
401 * \fn const uint8_t *cbor_value_get_next_byte(const CborValue *it)
402 *
403 * Returns a pointer to the next byte that would be decoded if this CborValue
404 * object were advanced.
405 *
406 * This function is useful if cbor_value_at_end() returns true for the
407 * outermost CborValue: the pointer returned is the first byte of the data
408 * remaining in the buffer, if any. Code can decide whether to begin decoding a
409 * new CBOR data stream from this point, or parse some other data appended to
410 * the same buffer.
411 *
412 * This function may be used even after a parsing error. If that occurred,
413 * then this function returns a pointer to where the parsing error occurred.
414 * Note that the error recovery is not precise and the pointer may not indicate
415 * the exact byte containing bad data.
416 *
417 * \sa cbor_value_at_end()
418 */
419
420 /**
421 * \fn bool cbor_value_is_valid(const CborValue *it)
422 *
423 * Returns true if the iterator \a it contains a valid value. Invalid iterators
424 * happen when iteration reaches the end of a container (see \ref
425 * cbor_value_at_end()) or when a search function resulted in no matches.
426 *
427 * \sa cbor_value_advance(), cbor_value_at_end(), cbor_value_get_type()
428 */
429
430 /**
431 * Performs a basic validation of the CBOR stream pointed by \a it and returns
432 * the error it found. If no error was found, it returns CborNoError and the
433 * application can iterate over the items with certainty that no other errors
434 * will appear during parsing.
435 *
436 * A basic validation checks for:
437 * \list
438 * \li absence of undefined additional information bytes;
439 * \li well-formedness of all numbers, lengths, and simple values;
440 * \li string contents match reported sizes;
441 * \li arrays and maps contain the number of elements they are reported to have;
442 * \endlist
443 *
444 * For further checks, see cbor_value_validate().
445 *
446 * This function has the same timing and memory requirements as
447 * cbor_value_advance().
448 *
449 * \sa cbor_value_validate(), cbor_value_advance()
450 */
451 CborError cbor_value_validate_basic(const CborValue *it)
452 {
453 CborValue value = *it;
454 return cbor_value_advance(&value);
455 }
456
457 /**
458 * Advances the CBOR value \a it by one fixed-size position. Fixed-size types
459 * are: integers, tags, simple types (including boolean, null and undefined
460 * values) and floating point types.
461 *
462 * If the type is not of fixed size, this function has undefined behavior. Code
463 * must be sure that the current type is one of the fixed-size types before
464 * calling this function. This function is provided because it can guarantee
465 * that it runs in constant time (O(1)).
466 *
467 * If the caller is not able to determine whether the type is fixed or not, code
468 * can use the cbor_value_advance() function instead.
469 *
470 * \sa cbor_value_at_end(), cbor_value_advance(), cbor_value_enter_container(), cbor_value_leave_container()
471 */
472 CborError cbor_value_advance_fixed(CborValue *it)
473 {
474 cbor_assert(it->type != CborInvalidType);
475 cbor_assert(is_fixed_type(it->type));
476 if (!it->remaining)
477 return CborErrorAdvancePastEOF;
478 return advance_internal(it);
479 }
480
481 static CborError advance_recursive(CborValue *it, int nestingLevel)
482 {
483 CborError err;
484 CborValue recursed;
485
486 if (is_fixed_type(it->type))
487 return advance_internal(it);
488
489 if (!cbor_value_is_container(it)) {
490 size_t len = SIZE_MAX;
491 return _cbor_value_copy_string(it, NULL, &len, it);
492 }
493
494 /* map or array */
495 if (nestingLevel == 0)
496 return CborErrorNestingTooDeep;
497
498 err = cbor_value_enter_container(it, &recursed);
499 if (err)
500 return err;
501 while (!cbor_value_at_end(&recursed)) {
502 err = advance_recursive(&recursed, nestingLevel - 1);
503 if (err)
504 return err;
505 }
506 return cbor_value_leave_container(it, &recursed);
507 }
508
509
510 /**
511 * Advances the CBOR value \a it by one element, skipping over containers.
512 * Unlike cbor_value_advance_fixed(), this function can be called on a CBOR
513 * value of any type. However, if the type is a container (map or array) or a
514 * string with a chunked payload, this function will not run in constant time
515 * and will recurse into itself (it will run on O(n) time for the number of
516 * elements or chunks and will use O(n) memory for the number of nested
517 * containers).
518 *
519 * The number of recursions can be limited at compile time to avoid stack
520 * exhaustion in constrained systems.
521 *
522 * \sa cbor_value_at_end(), cbor_value_advance_fixed(), cbor_value_enter_container(), cbor_value_leave_container()
523 */
524 CborError cbor_value_advance(CborValue *it)
525 {
526 cbor_assert(it->type != CborInvalidType);
527 if (!it->remaining)
528 return CborErrorAdvancePastEOF;
529 return advance_recursive(it, CBOR_PARSER_MAX_RECURSIONS);
530 }
531
532 /**
533 * \fn bool cbor_value_is_tag(const CborValue *value)
534 *
535 * Returns true if the iterator \a value is valid and points to a CBOR tag.
536 *
537 * \sa cbor_value_get_tag(), cbor_value_skip_tag()
538 */
539
540 /**
541 * \fn CborError cbor_value_get_tag(const CborValue *value, CborTag *result)
542 *
543 * Retrieves the CBOR tag value that \a value points to and stores it in \a
544 * result. If the iterator \a value does not point to a CBOR tag value, the
545 * behavior is undefined, so checking with \ref cbor_value_get_type or with
546 * \ref cbor_value_is_tag is recommended.
547 *
548 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_tag()
549 */
550
551 /**
552 * Advances the CBOR value \a it until it no longer points to a tag. If \a it is
553 * already not pointing to a tag, then this function returns it unchanged.
554 *
555 * This function does not run in constant time: it will run on O(n) for n being
556 * the number of tags. It does use constant memory (O(1) memory requirements).
557 *
558 * \sa cbor_value_advance_fixed(), cbor_value_advance()
559 */
560 CborError cbor_value_skip_tag(CborValue *it)
561 {
562 while (cbor_value_is_tag(it)) {
563 CborError err = cbor_value_advance_fixed(it);
564 if (err)
565 return err;
566 }
567 return CborNoError;
568 }
569
570 /**
571 * \fn bool cbor_value_is_container(const CborValue *it)
572 *
573 * Returns true if the \a it value is a container and requires recursion in
574 * order to decode (maps and arrays), false otherwise.
575 */
576
577 /**
578 * Creates a CborValue iterator pointing to the first element of the container
579 * represented by \a it and saves it in \a recursed. The \a it container object
580 * needs to be kept and passed again to cbor_value_leave_container() in order
581 * to continue iterating past this container.
582 *
583 * The \a it CborValue iterator must point to a container.
584 *
585 * \sa cbor_value_is_container(), cbor_value_leave_container(), cbor_value_advance()
586 */
587 CborError cbor_value_enter_container(const CborValue *it, CborValue *recursed)
588 {
589 cbor_assert(cbor_value_is_container(it));
590 *recursed = *it;
591
592 if (it->flags & CborIteratorFlag_UnknownLength) {
593 recursed->remaining = UINT32_MAX;
594 ++recursed->ptr;
595 } else {
596 uint64_t len;
597 CborError err = _cbor_value_extract_number(&recursed->ptr, recursed->parser->end, &len);
598 cbor_assert(err == CborNoError);
599
600 recursed->remaining = (uint32_t)len;
601 if (recursed->remaining != len || len == UINT32_MAX) {
602 /* back track the pointer to indicate where the error occurred */
603 recursed->ptr = it->ptr;
604 return CborErrorDataTooLarge;
605 }
606 if (recursed->type == CborMapType) {
607 /* maps have keys and values, so we need to multiply by 2 */
608 if (recursed->remaining > UINT32_MAX / 2) {
609 /* back track the pointer to indicate where the error occurred */
610 recursed->ptr = it->ptr;
611 return CborErrorDataTooLarge;
612 }
613 recursed->remaining *= 2;
614 }
615 if (len == 0) {
616 /* the case of the empty container */
617 recursed->type = CborInvalidType;
618 return CborNoError;
619 }
620 }
621 return preparse_next_value_nodecrement(recursed);
622 }
623
624 /**
625 * Updates \a it to point to the next element after the container. The \a
626 * recursed object needs to point to the element obtained either by advancing
627 * the last element of the container (via cbor_value_advance(),
628 * cbor_value_advance_fixed(), a nested cbor_value_leave_container(), or the \c
629 * next pointer from cbor_value_copy_string() or cbor_value_dup_string()).
630 *
631 * The \a it and \a recursed parameters must be the exact same as passed to
632 * cbor_value_enter_container().
633 *
634 * \sa cbor_value_enter_container(), cbor_value_at_end()
635 */
636 CborError cbor_value_leave_container(CborValue *it, const CborValue *recursed)
637 {
638 cbor_assert(cbor_value_is_container(it));
639 cbor_assert(recursed->type == CborInvalidType);
640 it->ptr = recursed->ptr;
641 return preparse_next_value(it);
642 }
643
644
645 /**
646 * \fn CborType cbor_value_get_type(const CborValue *value)
647 *
648 * Returns the type of the CBOR value that the iterator \a value points to. If
649 * \a value does not point to a valid value, this function returns \ref
650 * CborInvalidType.
651 *
652 * TinyCBOR also provides functions to test directly if a given CborValue object
653 * is of a given type, like cbor_value_is_text_string() and cbor_value_is_null().
654 *
655 * \sa cbor_value_is_valid()
656 */
657
658 /**
659 * \fn bool cbor_value_is_null(const CborValue *value)
660 *
661 * Returns true if the iterator \a value is valid and points to a CBOR null type.
662 *
663 * \sa cbor_value_is_valid(), cbor_value_is_undefined()
664 */
665
666 /**
667 * \fn bool cbor_value_is_undefined(const CborValue *value)
668 *
669 * Returns true if the iterator \a value is valid and points to a CBOR undefined type.
670 *
671 * \sa cbor_value_is_valid(), cbor_value_is_null()
672 */
673
674 /**
675 * \fn bool cbor_value_is_boolean(const CborValue *value)
676 *
677 * Returns true if the iterator \a value is valid and points to a CBOR boolean
678 * type (true or false).
679 *
680 * \sa cbor_value_is_valid(), cbor_value_get_boolean()
681 */
682
683 /**
684 * \fn CborError cbor_value_get_boolean(const CborValue *value, bool *result)
685 *
686 * Retrieves the boolean value that \a value points to and stores it in \a
687 * result. If the iterator \a value does not point to a boolean value, the
688 * behavior is undefined, so checking with \ref cbor_value_get_type or with
689 * \ref cbor_value_is_boolean is recommended.
690 *
691 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_boolean()
692 */
693
694 /**
695 * \fn bool cbor_value_is_simple_type(const CborValue *value)
696 *
697 * Returns true if the iterator \a value is valid and points to a CBOR Simple Type
698 * type (other than true, false, null and undefined).
699 *
700 * \sa cbor_value_is_valid(), cbor_value_get_simple_type()
701 */
702
703 /**
704 * \fn CborError cbor_value_get_simple_type(const CborValue *value, uint8_t *result)
705 *
706 * Retrieves the CBOR Simple Type value that \a value points to and stores it
707 * in \a result. If the iterator \a value does not point to a simple_type
708 * value, the behavior is undefined, so checking with \ref cbor_value_get_type
709 * or with \ref cbor_value_is_simple_type is recommended.
710 *
711 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_simple_type()
712 */
713
714 /**
715 * \fn bool cbor_value_is_integer(const CborValue *value)
716 *
717 * Returns true if the iterator \a value is valid and points to a CBOR integer
718 * type.
719 *
720 * \sa cbor_value_is_valid(), cbor_value_get_int, cbor_value_get_int64, cbor_value_get_uint64, cbor_value_get_raw_integer
721 */
722
723 /**
724 * \fn bool cbor_value_is_unsigned_integer(const CborValue *value)
725 *
726 * Returns true if the iterator \a value is valid and points to a CBOR unsigned
727 * integer type (positive values or zero).
728 *
729 * \sa cbor_value_is_valid(), cbor_value_get_uint64()
730 */
731
732 /**
733 * \fn bool cbor_value_is_negative_integer(const CborValue *value)
734 *
735 * Returns true if the iterator \a value is valid and points to a CBOR negative
736 * integer type.
737 *
738 * \sa cbor_value_is_valid(), cbor_value_get_int, cbor_value_get_int64, cbor_value_get_raw_integer
739 */
740
741 /**
742 * \fn CborError cbor_value_get_int(const CborValue *value, int *result)
743 *
744 * Retrieves the CBOR integer value that \a value points to and stores it in \a
745 * result. If the iterator \a value does not point to an integer value, the
746 * behavior is undefined, so checking with \ref cbor_value_get_type or with
747 * \ref cbor_value_is_integer is recommended.
748 *
749 * Note that this function does not do range-checking: integral values that do
750 * not fit in a variable of type \c{int} are silently truncated to fit. Use
751 * cbor_value_get_int_checked() if that is not acceptable.
752 *
753 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_integer()
754 */
755
756 /**
757 * \fn CborError cbor_value_get_int64(const CborValue *value, int64_t *result)
758 *
759 * Retrieves the CBOR integer value that \a value points to and stores it in \a
760 * result. If the iterator \a value does not point to an integer value, the
761 * behavior is undefined, so checking with \ref cbor_value_get_type or with
762 * \ref cbor_value_is_integer is recommended.
763 *
764 * Note that this function does not do range-checking: integral values that do
765 * not fit in a variable of type \c{int64_t} are silently truncated to fit. Use
766 * cbor_value_get_int64_checked() that is not acceptable.
767 *
768 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_integer()
769 */
770
771 /**
772 * \fn CborError cbor_value_get_uint64(const CborValue *value, uint64_t *result)
773 *
774 * Retrieves the CBOR integer value that \a value points to and stores it in \a
775 * result. If the iterator \a value does not point to an unsigned integer
776 * value, the behavior is undefined, so checking with \ref cbor_value_get_type
777 * or with \ref cbor_value_is_unsigned_integer is recommended.
778 *
779 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_unsigned_integer()
780 */
781
782 /**
783 * \fn CborError cbor_value_get_raw_integer(const CborValue *value, uint64_t *result)
784 *
785 * Retrieves the CBOR integer value that \a value points to and stores it in \a
786 * result. If the iterator \a value does not point to an integer value, the
787 * behavior is undefined, so checking with \ref cbor_value_get_type or with
788 * \ref cbor_value_is_integer is recommended.
789 *
790 * This function is provided because CBOR negative integers can assume values
791 * that cannot be represented with normal 64-bit integer variables.
792 *
793 * If the integer is unsigned (that is, if cbor_value_is_unsigned_integer()
794 * returns true), then \a result will contain the actual value. If the integer
795 * is negative, then \a result will contain the absolute value of that integer,
796 * minus one. That is, \c {actual = -result - 1}. On architectures using two's
797 * complement for representation of negative integers, it is equivalent to say
798 * that \a result will contain the bitwise negation of the actual value.
799 *
800 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_integer()
801 */
802
803 /**
804 * Retrieves the CBOR integer value that \a value points to and stores it in \a
805 * result. If the iterator \a value does not point to an integer value, the
806 * behavior is undefined, so checking with \ref cbor_value_get_type or with
807 * \ref cbor_value_is_integer is recommended.
808 *
809 * Unlike \ref cbor_value_get_int64(), this function performs a check to see if the
810 * stored integer fits in \a result without data loss. If the number is outside
811 * the valid range for the data type, this function returns the recoverable
812 * error CborErrorDataTooLarge. In that case, use either
813 * cbor_value_get_uint64() (if the number is positive) or
814 * cbor_value_get_raw_integer().
815 *
816 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_integer(), cbor_value_get_int64()
817 */
818 CborError cbor_value_get_int64_checked(const CborValue *value, int64_t *result)
819 {
820 uint64_t v;
821 cbor_assert(cbor_value_is_integer(value));
822 v = _cbor_value_extract_int64_helper(value);
823
824 /* Check before converting, as the standard says (C11 6.3.1.3 paragraph 3):
825 * "[if] the new type is signed and the value cannot be represented in it; either the
826 * result is implementation-defined or an implementation-defined signal is raised."
827 *
828 * The range for int64_t is -2^63 to 2^63-1 (int64_t is required to be
829 * two's complement, C11 7.20.1.1 paragraph 3), which in CBOR is
830 * represented the same way, differing only on the "sign bit" (the major
831 * type).
832 */
833
834 if (unlikely(v > (uint64_t)INT64_MAX))
835 return CborErrorDataTooLarge;
836
837 *result = v;
838 if (value->flags & CborIteratorFlag_NegativeInteger)
839 *result = -*result - 1;
840 return CborNoError;
841 }
842
843 /**
844 * Retrieves the CBOR integer value that \a value points to and stores it in \a
845 * result. If the iterator \a value does not point to an integer value, the
846 * behavior is undefined, so checking with \ref cbor_value_get_type or with
847 * \ref cbor_value_is_integer is recommended.
848 *
849 * Unlike \ref cbor_value_get_int(), this function performs a check to see if the
850 * stored integer fits in \a result without data loss. If the number is outside
851 * the valid range for the data type, this function returns the recoverable
852 * error CborErrorDataTooLarge. In that case, use one of the other integer
853 * functions to obtain the value.
854 *
855 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_integer(), cbor_value_get_int64(),
856 * cbor_value_get_uint64(), cbor_value_get_int64_checked(), cbor_value_get_raw_integer()
857 */
858 CborError cbor_value_get_int_checked(const CborValue *value, int *result)
859 {
860 uint64_t v;
861 cbor_assert(cbor_value_is_integer(value));
862 v = _cbor_value_extract_int64_helper(value);
863
864 /* Check before converting, as the standard says (C11 6.3.1.3 paragraph 3):
865 * "[if] the new type is signed and the value cannot be represented in it; either the
866 * result is implementation-defined or an implementation-defined signal is raised."
867 *
868 * But we can convert from signed to unsigned without fault (paragraph 2).
869 *
870 * The range for int is implementation-defined and int is not guaranteed to use
871 * two's complement representation (although int32_t is).
872 */
873
874 if (value->flags & CborIteratorFlag_NegativeInteger) {
875 if (unlikely(v > (unsigned) -(INT_MIN + 1)))
876 return CborErrorDataTooLarge;
877
878 *result = (int)v;
879 *result = -*result - 1;
880 } else {
881 if (unlikely(v > (uint64_t)INT_MAX))
882 return CborErrorDataTooLarge;
883
884 *result = (int)v;
885 }
886 return CborNoError;
887
888 }
889
890 /**
891 * \fn bool cbor_value_is_length_known(const CborValue *value)
892 *
893 * Returns true if the length of this type is known without calculation. That
894 * is, if the length of this CBOR string, map or array is encoded in the data
895 * stream, this function returns true. If the length is not encoded, it returns
896 * false.
897 *
898 * If the length is known, code can call cbor_value_get_string_length(),
899 * cbor_value_get_array_length() or cbor_value_get_map_length() to obtain the
900 * length. If the length is not known but is necessary, code can use the
901 * cbor_value_calculate_string_length() function (no equivalent function is
902 * provided for maps and arrays).
903 */
904
905 /**
906 * \fn bool cbor_value_is_text_string(const CborValue *value)
907 *
908 * Returns true if the iterator \a value is valid and points to a CBOR text
909 * string. CBOR text strings are UTF-8 encoded and usually contain
910 * human-readable text.
911 *
912 * \sa cbor_value_is_valid(), cbor_value_get_string_length(), cbor_value_calculate_string_length(),
913 * cbor_value_copy_text_string(), cbor_value_dup_text_string()
914 */
915
916 /**
917 * \fn bool cbor_value_is_byte_string(const CborValue *value)
918 *
919 * Returns true if the iterator \a value is valid and points to a CBOR text
920 * string. CBOR byte strings are binary data with no specified encoding or
921 * format.
922 *
923 * \sa cbor_value_is_valid(), cbor_value_get_string_length(), cbor_value_calculate_string_length(),
924 * cbor_value_copy_byte_string(), cbor_value_dup_byte_string()
925 */
926
927 /**
928 * \fn CborError cbor_value_get_string_length(const CborValue *value, size_t *length)
929 *
930 * Extracts the length of the byte or text string that \a value points to and
931 * stores it in \a result. If the iterator \a value does not point to a text
932 * string or a byte string, the behaviour is undefined, so checking with \ref
933 * cbor_value_get_type, with \ref cbor_value_is_text_string or \ref
934 * cbor_value_is_byte_string is recommended.
935 *
936 * If the length of this string is not encoded in the CBOR data stream, this
937 * function will return the recoverable error CborErrorUnknownLength. You may
938 * also check whether that is the case by using cbor_value_is_length_known().
939 *
940 * If the length of the string is required but the length was not encoded, use
941 * cbor_value_calculate_string_length(), but note that that function does not
942 * run in constant time.
943 *
944 * \note On 32-bit platforms, this function will return error condition of \ref
945 * CborErrorDataTooLarge if the stream indicates a length that is too big to
946 * fit in 32-bit.
947 *
948 * \sa cbor_value_is_valid(), cbor_value_is_length_known(), cbor_value_calculate_string_length()
949 */
950
951 /**
952 * Calculates the length of the byte or text string that \a value points to and
953 * stores it in \a len. If the iterator \a value does not point to a text
954 * string or a byte string, the behaviour is undefined, so checking with \ref
955 * cbor_value_get_type, with \ref cbor_value_is_text_string or \ref
956 * cbor_value_is_byte_string is recommended.
957 *
958 * This function is different from cbor_value_get_string_length() in that it
959 * calculates the length even for strings sent in chunks. For that reason, this
960 * function may not run in constant time (it will run in O(n) time on the
961 * number of chunks). It does use constant memory (O(1)).
962 *
963 * \note On 32-bit platforms, this function will return error condition of \ref
964 * CborErrorDataTooLarge if the stream indicates a length that is too big to
965 * fit in 32-bit.
966 *
967 * \sa cbor_value_get_string_length(), cbor_value_copy_text_string(), cbor_value_copy_byte_string(), cbor_value_is_length_known()
968 */
969 CborError cbor_value_calculate_string_length(const CborValue *value, size_t *len)
970 {
971 *len = SIZE_MAX;
972 return _cbor_value_copy_string(value, NULL, len, NULL);
973 }
974
975 static inline void prepare_string_iteration(CborValue *it)
976 {
977 if (!cbor_value_is_length_known(it)) {
978 /* chunked string: we're before the first chunk;
979 * advance to the first chunk */
980 ++it->ptr;
981 it->flags |= CborIteratorFlag_IteratingStringChunks;
982 }
983 }
984
985 CborError CBOR_INTERNAL_API_CC _cbor_value_prepare_string_iteration(CborValue *it)
986 {
987 cbor_assert((it->flags & CborIteratorFlag_IteratingStringChunks) == 0);
988 prepare_string_iteration(it);
989
990 /* are we at the end? */
991 if (it->ptr == it->parser->end)
992 return CborErrorUnexpectedEOF;
993 return CborNoError;
994 }
995
996 static CborError get_string_chunk(CborValue *it, const void **bufferptr, size_t *len)
997 {
998 CborError err;
999
1000 /* Possible states:
1001 * length known | iterating | meaning
1002 * no | no | before the first chunk of a chunked string
1003 * yes | no | at a non-chunked string
1004 * no | yes | second or later chunk
1005 * yes | yes | after a non-chunked string
1006 */
1007 if (it->flags & CborIteratorFlag_IteratingStringChunks) {
1008 /* already iterating */
1009 if (cbor_value_is_length_known(it)) {
1010 /* if the length was known, it wasn't chunked, so finish iteration */
1011 goto last_chunk;
1012 }
1013 } else {
1014 prepare_string_iteration(it);
1015 }
1016
1017 /* are we at the end? */
1018 if (it->ptr == it->parser->end)
1019 return CborErrorUnexpectedEOF;
1020
1021 if (*it->ptr == BreakByte) {
1022 /* last chunk */
1023 ++it->ptr;
1024 last_chunk:
1025 *bufferptr = NULL;
1026 *len = 0;
1027 return preparse_next_value(it);
1028 } else if ((uint8_t)(*it->ptr & MajorTypeMask) == it->type) {
1029 err = extract_length(it->parser, &it->ptr, len);
1030 if (err)
1031 return err;
1032 if (*len > (size_t)(it->parser->end - it->ptr))
1033 return CborErrorUnexpectedEOF;
1034
1035 *bufferptr = it->ptr;
1036 it->ptr += *len;
1037 } else {
1038 return CborErrorIllegalType;
1039 }
1040
1041 it->flags |= CborIteratorFlag_IteratingStringChunks;
1042 return CborNoError;
1043 }
1044
1045 CborError CBOR_INTERNAL_API_CC
1046 _cbor_value_get_string_chunk(const CborValue *value, const void **bufferptr,
1047 size_t *len, CborValue *next)
1048 {
1049 CborValue tmp;
1050 if (!next)
1051 next = &tmp;
1052 *next = *value;
1053 return get_string_chunk(next, bufferptr, len);
1054 }
1055
1056 /* We return uintptr_t so that we can pass memcpy directly as the iteration
1057 * function. The choice is to optimize for memcpy, which is used in the base
1058 * parser API (cbor_value_copy_string), while memcmp is used in convenience API
1059 * only. */
1060 typedef uintptr_t (*IterateFunction)(char *, const uint8_t *, size_t);
1061
1062 static uintptr_t iterate_noop(char *dest, const uint8_t *src, size_t len)
1063 {
1064 (void)dest;
1065 (void)src;
1066 (void)len;
1067 return true;
1068 }
1069
1070 static uintptr_t iterate_memcmp(char *s1, const uint8_t *s2, size_t len)
1071 {
1072 return memcmp(s1, (const char *)s2, len) == 0;
1073 }
1074
1075 static uintptr_t iterate_memcpy(char *dest, const uint8_t *src, size_t len)
1076 {
1077 return (uintptr_t)memcpy(dest, src, len);
1078 }
1079
1080 static CborError iterate_string_chunks(const CborValue *value, char *buffer, size_t *buflen,
1081 bool *result, CborValue *next, IterateFunction func)
1082 {
1083 CborError err;
1084 CborValue tmp;
1085 size_t total = 0;
1086 const void *ptr;
1087
1088 cbor_assert(cbor_value_is_byte_string(value) || cbor_value_is_text_string(value));
1089 if (!next)
1090 next = &tmp;
1091 *next = *value;
1092 *result = true;
1093
1094 while (1) {
1095 size_t newTotal;
1096 size_t chunkLen;
1097 err = get_string_chunk(next, &ptr, &chunkLen);
1098 if (err)
1099 return err;
1100 if (!ptr)
1101 break;
1102
1103 if (unlikely(add_check_overflow(total, chunkLen, &newTotal)))
1104 return CborErrorDataTooLarge;
1105
1106 if (*result && *buflen >= newTotal)
1107 *result = !!func(buffer + total, (const uint8_t *)ptr, chunkLen);
1108 else
1109 *result = false;
1110
1111 total = newTotal;
1112 }
1113
1114 /* is there enough room for the ending NUL byte? */
1115 if (*result && *buflen > total) {
1116 uint8_t nul[] = { 0 };
1117 *result = !!func(buffer + total, nul, 1);
1118 }
1119 *buflen = total;
1120 return CborNoError;
1121 }
1122
1123 /**
1124 * \fn CborError cbor_value_copy_text_string(const CborValue *value, char *buffer, size_t *buflen, CborValue *next)
1125 *
1126 * Copies the string pointed to by \a value into the buffer provided at \a buffer
1127 * of \a buflen bytes. If \a buffer is a NULL pointer, this function will not
1128 * copy anything and will only update the \a next value.
1129 *
1130 * If the iterator \a value does not point to a text string, the behaviour is
1131 * undefined, so checking with \ref cbor_value_get_type or \ref
1132 * cbor_value_is_text_string is recommended.
1133 *
1134 * If the provided buffer length was too small, this function returns an error
1135 * condition of \ref CborErrorOutOfMemory. If you need to calculate the length
1136 * of the string in order to preallocate a buffer, use
1137 * cbor_value_calculate_string_length().
1138 *
1139 * On success, this function sets the number of bytes copied to \c{*buflen}. If
1140 * the buffer is large enough, this function will insert a null byte after the
1141 * last copied byte, to facilitate manipulation of text strings. That byte is
1142 * not included in the returned value of \c{*buflen}. If there was no space for
1143 * the terminating null, no error is returned, so callers must check the value
1144 * of *buflen after the call, before relying on the '\0'; if it has not been
1145 * changed by the call, there is no '\0'-termination on the buffer's contents.
1146 *
1147 * The \a next pointer, if not null, will be updated to point to the next item
1148 * after this string. If \a value points to the last item, then \a next will be
1149 * invalid.
1150 *
1151 * This function may not run in constant time (it will run in O(n) time on the
1152 * number of chunks). It requires constant memory (O(1)).
1153 *
1154 * \note This function does not perform UTF-8 validation on the incoming text
1155 * string.
1156 *
1157 * \sa cbor_value_get_text_string_chunk() cbor_value_dup_text_string(), cbor_value_copy_byte_string(), cbor_value_get_string_length(), cbor_value_calculate_string_length()
1158 */
1159
1160 /**
1161 * \fn CborError cbor_value_copy_byte_string(const CborValue *value, uint8_t *buffer, size_t *buflen, CborValue *next)
1162 *
1163 * Copies the string pointed by \a value into the buffer provided at \a buffer
1164 * of \a buflen bytes. If \a buffer is a NULL pointer, this function will not
1165 * copy anything and will only update the \a next value.
1166 *
1167 * If the iterator \a value does not point to a byte string, the behaviour is
1168 * undefined, so checking with \ref cbor_value_get_type or \ref
1169 * cbor_value_is_byte_string is recommended.
1170 *
1171 * If the provided buffer length was too small, this function returns an error
1172 * condition of \ref CborErrorOutOfMemory. If you need to calculate the length
1173 * of the string in order to preallocate a buffer, use
1174 * cbor_value_calculate_string_length().
1175 *
1176 * On success, this function sets the number of bytes copied to \c{*buflen}. If
1177 * the buffer is large enough, this function will insert a null byte after the
1178 * last copied byte, to facilitate manipulation of null-terminated strings.
1179 * That byte is not included in the returned value of \c{*buflen}.
1180 *
1181 * The \a next pointer, if not null, will be updated to point to the next item
1182 * after this string. If \a value points to the last item, then \a next will be
1183 * invalid.
1184 *
1185 * This function may not run in constant time (it will run in O(n) time on the
1186 * number of chunks). It requires constant memory (O(1)).
1187 *
1188 * \sa cbor_value_get_byte_string_chunk(), cbor_value_dup_text_string(), cbor_value_copy_text_string(), cbor_value_get_string_length(), cbor_value_calculate_string_length()
1189 */
1190
1191 CborError _cbor_value_copy_string(const CborValue *value, void *buffer,
1192 size_t *buflen, CborValue *next)
1193 {
1194 bool copied_all;
1195 CborError err = iterate_string_chunks(value, (char*)buffer, buflen, &copied_all, next,
1196 buffer ? iterate_memcpy : iterate_noop);
1197 return err ? err :
1198 copied_all ? CborNoError : CborErrorOutOfMemory;
1199 }
1200
1201 /**
1202 * Compares the entry \a value with the string \a string and stores the result
1203 * in \a result. If the value is different from \a string \a result will
1204 * contain \c false.
1205 *
1206 * The entry at \a value may be a tagged string. If \a value is not a string or
1207 * a tagged string, the comparison result will be false.
1208 *
1209 * CBOR requires text strings to be encoded in UTF-8, but this function does
1210 * not validate either the strings in the stream or the string \a string to be
1211 * matched. Moreover, comparison is done on strict codepoint comparison,
1212 * without any Unicode normalization.
1213 *
1214 * This function may not run in constant time (it will run in O(n) time on the
1215 * number of chunks). It requires constant memory (O(1)).
1216 *
1217 * \sa cbor_value_skip_tag(), cbor_value_copy_text_string()
1218 */
1219 CborError cbor_value_text_string_equals(const CborValue *value, const char *string, bool *result)
1220 {
1221 size_t len;
1222 CborValue copy = *value;
1223 CborError err = cbor_value_skip_tag(&copy);
1224 if (err)
1225 return err;
1226 if (!cbor_value_is_text_string(&copy)) {
1227 *result = false;
1228 return CborNoError;
1229 }
1230
1231 len = strlen(string);
1232 return iterate_string_chunks(&copy, CONST_CAST(char *, string), &len, result, NULL, iterate_memcmp);
1233 }
1234
1235 /**
1236 * \fn bool cbor_value_is_array(const CborValue *value)
1237 *
1238 * Returns true if the iterator \a value is valid and points to a CBOR array.
1239 *
1240 * \sa cbor_value_is_valid(), cbor_value_is_map()
1241 */
1242
1243 /**
1244 * \fn CborError cbor_value_get_array_length(const CborValue *value, size_t *length)
1245 *
1246 * Extracts the length of the CBOR array that \a value points to and stores it
1247 * in \a result. If the iterator \a value does not point to a CBOR array, the
1248 * behaviour is undefined, so checking with \ref cbor_value_get_type or \ref
1249 * cbor_value_is_array is recommended.
1250 *
1251 * If the length of this array is not encoded in the CBOR data stream, this
1252 * function will return the recoverable error CborErrorUnknownLength. You may
1253 * also check whether that is the case by using cbor_value_is_length_known().
1254 *
1255 * \note On 32-bit platforms, this function will return error condition of \ref
1256 * CborErrorDataTooLarge if the stream indicates a length that is too big to
1257 * fit in 32-bit.
1258 *
1259 * \sa cbor_value_is_valid(), cbor_value_is_length_known()
1260 */
1261
1262 /**
1263 * \fn bool cbor_value_is_map(const CborValue *value)
1264 *
1265 * Returns true if the iterator \a value is valid and points to a CBOR map.
1266 *
1267 * \sa cbor_value_is_valid(), cbor_value_is_array()
1268 */
1269
1270 /**
1271 * \fn CborError cbor_value_get_map_length(const CborValue *value, size_t *length)
1272 *
1273 * Extracts the length of the CBOR map that \a value points to and stores it in
1274 * \a result. If the iterator \a value does not point to a CBOR map, the
1275 * behaviour is undefined, so checking with \ref cbor_value_get_type or \ref
1276 * cbor_value_is_map is recommended.
1277 *
1278 * If the length of this map is not encoded in the CBOR data stream, this
1279 * function will return the recoverable error CborErrorUnknownLength. You may
1280 * also check whether that is the case by using cbor_value_is_length_known().
1281 *
1282 * \note On 32-bit platforms, this function will return error condition of \ref
1283 * CborErrorDataTooLarge if the stream indicates a length that is too big to
1284 * fit in 32-bit.
1285 *
1286 * \sa cbor_value_is_valid(), cbor_value_is_length_known()
1287 */
1288
1289 /**
1290 * Attempts to find the value in map \a map that corresponds to the text string
1291 * entry \a string. If the iterator \a value does not point to a CBOR map, the
1292 * behaviour is undefined, so checking with \ref cbor_value_get_type or \ref
1293 * cbor_value_is_map is recommended.
1294 *
1295 * If the item is found, it is stored in \a result. If no item is found
1296 * matching the key, then \a result will contain an element of type \ref
1297 * CborInvalidType. Matching is performed using
1298 * cbor_value_text_string_equals(), so tagged strings will also match.
1299 *
1300 * This function has a time complexity of O(n) where n is the number of
1301 * elements in the map to be searched. In addition, this function is has O(n)
1302 * memory requirement based on the number of nested containers (maps or arrays)
1303 * found as elements of this map.
1304 *
1305 * \sa cbor_value_is_valid(), cbor_value_text_string_equals(), cbor_value_advance()
1306 */
1307 CborError cbor_value_map_find_value(const CborValue *map, const char *string, CborValue *element)
1308 {
1309 CborError err;
1310 size_t len = strlen(string);
1311 cbor_assert(cbor_value_is_map(map));
1312 err = cbor_value_enter_container(map, element);
1313 if (err)
1314 goto error;
1315
1316 while (!cbor_value_at_end(element)) {
1317 /* find the non-tag so we can compare */
1318 err = cbor_value_skip_tag(element);
1319 if (err)
1320 goto error;
1321 if (cbor_value_is_text_string(element)) {
1322 bool equals;
1323 size_t dummyLen = len;
1324 err = iterate_string_chunks(element, CONST_CAST(char *, string), &dummyLen,
1325 &equals, element, iterate_memcmp);
1326 if (err)
1327 goto error;
1328 if (equals)
1329 return preparse_value(element);
1330 } else {
1331 /* skip this key */
1332 err = cbor_value_advance(element);
1333 if (err)
1334 goto error;
1335 }
1336
1337 /* skip this value */
1338 err = cbor_value_skip_tag(element);
1339 if (err)
1340 goto error;
1341 err = cbor_value_advance(element);
1342 if (err)
1343 goto error;
1344 }
1345
1346 /* not found */
1347 element->type = CborInvalidType;
1348 return CborNoError;
1349
1350 error:
1351 element->type = CborInvalidType;
1352 return err;
1353 }
1354
1355 /**
1356 * \fn bool cbor_value_is_float(const CborValue *value)
1357 *
1358 * Returns true if the iterator \a value is valid and points to a CBOR
1359 * single-precision floating point (32-bit).
1360 *
1361 * \sa cbor_value_is_valid(), cbor_value_is_double(), cbor_value_is_half_float()
1362 */
1363
1364 /**
1365 * \fn CborError cbor_value_get_float(const CborValue *value, float *result)
1366 *
1367 * Retrieves the CBOR single-precision floating point (32-bit) value that \a
1368 * value points to and stores it in \a result. If the iterator \a value does
1369 * not point to a single-precision floating point value, the behavior is
1370 * undefined, so checking with \ref cbor_value_get_type or with \ref
1371 * cbor_value_is_float is recommended.
1372 *
1373 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_float(), cbor_value_get_double()
1374 */
1375
1376 /**
1377 * \fn bool cbor_value_is_double(const CborValue *value)
1378 *
1379 * Returns true if the iterator \a value is valid and points to a CBOR
1380 * double-precision floating point (64-bit).
1381 *
1382 * \sa cbor_value_is_valid(), cbor_value_is_float(), cbor_value_is_half_float()
1383 */
1384
1385 /**
1386 * \fn CborError cbor_value_get_double(const CborValue *value, float *result)
1387 *
1388 * Retrieves the CBOR double-precision floating point (64-bit) value that \a
1389 * value points to and stores it in \a result. If the iterator \a value does
1390 * not point to a double-precision floating point value, the behavior is
1391 * undefined, so checking with \ref cbor_value_get_type or with \ref
1392 * cbor_value_is_double is recommended.
1393 *
1394 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_double(), cbor_value_get_float()
1395 */
1396
1397 /**
1398 * \fn bool cbor_value_is_half_float(const CborValue *value)
1399 *
1400 * Returns true if the iterator \a value is valid and points to a CBOR
1401 * single-precision floating point (16-bit).
1402 *
1403 * \sa cbor_value_is_valid(), cbor_value_is_double(), cbor_value_is_float()
1404 */
1405
1406 /**
1407 * Retrieves the CBOR half-precision floating point (16-bit) value that \a
1408 * value points to and stores it in \a result. If the iterator \a value does
1409 * not point to a half-precision floating point value, the behavior is
1410 * undefined, so checking with \ref cbor_value_get_type or with \ref
1411 * cbor_value_is_half_float is recommended.
1412 *
1413 * Note: since the C language does not have a standard type for half-precision
1414 * floating point, this function takes a \c{void *} as a parameter for the
1415 * storage area, which must be at least 16 bits wide.
1416 *
1417 * \sa cbor_value_get_type(), cbor_value_is_valid(), cbor_value_is_half_float(), cbor_value_get_float()
1418 */
1419 CborError cbor_value_get_half_float(const CborValue *value, void *result)
1420 {
1421 uint16_t v;
1422 cbor_assert(cbor_value_is_half_float(value));
1423
1424 /* size has been computed already */
1425 v = get16(value->ptr + 1);
1426 memcpy(result, &v, sizeof(v));
1427 return CborNoError;
1428 }
1429
1430 /** @} */
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