1 /* pb_decode.c -- decode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
6 /* The warn_unused_result attribute appeared first in gcc-3.4.0 */
7 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
10 /* Verify that we remember to check all return values for proper error propagation */
11 #define checkreturn __attribute__((warn_unused_result))
14 #define NANOPB_INTERNALS
16 #include "pb_decode.h"
19 typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
21 /* --- Function pointers to field decoders ---
22 * Order in the array must match pb_action_t LTYPE numbering.
24 static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
39 static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
41 uint8_t *source = (uint8_t*)stream->state;
44 memcpy(buf, source, count);
46 stream->state = source + count;
50 bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
52 if (buf == NULL && stream->callback != buf_read)
54 /* Skip input bytes */
58 if (!pb_read(stream, tmp, 16))
64 return pb_read(stream, tmp, count);
67 if (stream->bytes_left < count)
68 PB_RETURN_ERROR(stream, "end-of-stream");
70 if (!stream->callback(stream, buf, count))
71 PB_RETURN_ERROR(stream, "io error");
73 stream->bytes_left -= count;
77 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
80 stream.callback = &buf_read;
82 stream.bytes_left = bufsize;
93 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
96 bool status = pb_decode_varint(stream, &temp);
97 *dest = (uint32_t)temp;
101 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
107 while (bitpos < 64 && pb_read(stream, &byte, 1))
109 *dest |= (uint64_t)(byte & 0x7F) << bitpos;
116 PB_RETURN_ERROR(stream, "varint overflow");
119 bool checkreturn pb_skip_varint(pb_istream_t *stream)
124 if (!pb_read(stream, &byte, 1))
126 } while (byte & 0x80);
130 bool checkreturn pb_skip_string(pb_istream_t *stream)
133 if (!pb_decode_varint32(stream, &length))
136 return pb_read(stream, NULL, length);
139 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
143 *wire_type = (pb_wire_type_t) 0;
146 if (!pb_decode_varint32(stream, &temp))
148 if (stream->bytes_left == 0)
156 *eof = true; /* Special feature: allow 0-terminated messages. */
161 *wire_type = (pb_wire_type_t)(temp & 7);
165 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
169 case PB_WT_VARINT: return pb_skip_varint(stream);
170 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
171 case PB_WT_STRING: return pb_skip_string(stream);
172 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
173 default: PB_RETURN_ERROR(stream, "invalid wire_type");
177 /* Read a raw value to buffer, for the purpose of passing it to callback as
178 * a substream. Size is maximum size on call, and actual size on return.
180 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
182 size_t max_size = *size;
190 if (*size > max_size) return false;
191 if (!pb_read(stream, buf, 1)) return false;
192 } while (*buf++ & 0x80);
197 return pb_read(stream, buf, 8);
201 return pb_read(stream, buf, 4);
203 default: PB_RETURN_ERROR(stream, "invalid wire_type");
207 /* Decode string length from stream and return a substream with limited length.
208 * Remember to close the substream using pb_close_string_substream().
210 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
213 if (!pb_decode_varint32(stream, &size))
216 *substream = *stream;
217 if (substream->bytes_left < size)
218 PB_RETURN_ERROR(stream, "parent stream too short");
220 substream->bytes_left = size;
221 stream->bytes_left -= size;
225 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
227 stream->state = substream->state;
230 stream->errmsg = substream->errmsg;
234 /* Iterator for pb_field_t list */
236 const pb_field_t *start; /* Start of the pb_field_t array */
237 const pb_field_t *current; /* Current position of the iterator */
238 int field_index; /* Zero-based index of the field. */
239 int required_field_index; /* Zero-based index that counts only the required fields */
240 void *dest_struct; /* Pointer to the destination structure to decode to */
241 void *pData; /* Pointer where to store current field value */
242 void *pSize; /* Pointer where to store the size of current array field */
243 } pb_field_iterator_t;
245 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
247 iter->start = iter->current = fields;
248 iter->field_index = 0;
249 iter->required_field_index = 0;
250 iter->pData = (char*)dest_struct + iter->current->data_offset;
251 iter->pSize = (char*)iter->pData + iter->current->size_offset;
252 iter->dest_struct = dest_struct;
255 static bool pb_field_next(pb_field_iterator_t *iter)
257 bool notwrapped = true;
258 size_t prev_size = iter->current->data_size;
260 if (PB_HTYPE(iter->current->type) == PB_HTYPE_ARRAY)
261 prev_size *= iter->current->array_size;
263 if (PB_HTYPE(iter->current->type) == PB_HTYPE_REQUIRED)
264 iter->required_field_index++;
268 if (iter->current->tag == 0)
270 iter->current = iter->start;
271 iter->field_index = 0;
272 iter->required_field_index = 0;
273 iter->pData = iter->dest_struct;
278 iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset;
279 iter->pSize = (char*)iter->pData + iter->current->size_offset;
283 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
285 int start = iter->field_index;
288 if (iter->current->tag == tag)
291 } while (iter->field_index != start);
296 /*************************
297 * Decode a single field *
298 *************************/
300 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
302 pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)];
304 switch (PB_HTYPE(iter->current->type))
306 case PB_HTYPE_REQUIRED:
307 return func(stream, iter->current, iter->pData);
309 case PB_HTYPE_OPTIONAL:
310 *(bool*)iter->pSize = true;
311 return func(stream, iter->current, iter->pData);
314 if (wire_type == PB_WT_STRING
315 && PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
319 size_t *size = (size_t*)iter->pSize;
320 pb_istream_t substream;
321 if (!pb_make_string_substream(stream, &substream))
324 while (substream.bytes_left && *size < iter->current->array_size)
326 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
327 if (!func(&substream, iter->current, pItem))
331 status = (substream.bytes_left == 0);
332 pb_close_string_substream(stream, &substream);
338 size_t *size = (size_t*)iter->pSize;
339 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
340 if (*size >= iter->current->array_size)
341 PB_RETURN_ERROR(stream, "array overflow");
344 return func(stream, iter->current, pItem);
347 case PB_HTYPE_CALLBACK:
349 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
351 if (pCallback->funcs.decode == NULL)
352 return pb_skip_field(stream, wire_type);
354 if (wire_type == PB_WT_STRING)
356 pb_istream_t substream;
358 if (!pb_make_string_substream(stream, &substream))
361 while (substream.bytes_left)
363 if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
364 PB_RETURN_ERROR(stream, "callback failed");
367 pb_close_string_substream(stream, &substream);
372 /* Copy the single scalar value to stack.
373 * This is required so that we can limit the stream length,
374 * which in turn allows to use same callback for packed and
375 * not-packed fields. */
376 pb_istream_t substream;
378 size_t size = sizeof(buffer);
380 if (!read_raw_value(stream, wire_type, buffer, &size))
382 substream = pb_istream_from_buffer(buffer, size);
384 return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
389 PB_RETURN_ERROR(stream, "invalid field type");
393 /* Initialize message fields to default values, recursively */
394 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
396 pb_field_iterator_t iter;
397 pb_field_init(&iter, fields, dest_struct);
399 /* Initialize size/has fields and apply default values */
402 if (iter.current->tag == 0)
405 /* Initialize the size field for optional/repeated fields to 0. */
406 if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
408 *(bool*)iter.pSize = false;
410 else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
412 *(size_t*)iter.pSize = 0;
413 continue; /* Array is empty, no need to initialize contents */
416 /* Initialize field contents to default value */
417 if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
419 continue; /* Don't overwrite callback */
421 else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
423 pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
425 else if (iter.current->ptr != NULL)
427 memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
431 memset(iter.pData, 0, iter.current->data_size);
433 } while (pb_field_next(&iter));
436 /*********************
437 * Decode all fields *
438 *********************/
440 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
442 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
443 pb_field_iterator_t iter;
445 pb_field_init(&iter, fields, dest_struct);
447 while (stream->bytes_left)
450 pb_wire_type_t wire_type;
453 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
461 if (!pb_field_find(&iter, tag))
463 /* No match found, skip data */
464 if (!pb_skip_field(stream, wire_type))
469 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
470 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
472 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
475 if (!decode_field(stream, wire_type, &iter))
479 /* Check that all required fields were present. */
480 pb_field_init(&iter, fields, dest_struct);
482 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED &&
483 iter.required_field_index < PB_MAX_REQUIRED_FIELDS &&
484 !(fields_seen[iter.required_field_index >> 3] & (1 << (iter.required_field_index & 7))))
486 PB_RETURN_ERROR(stream, "missing required field");
488 } while (pb_field_next(&iter));
493 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
495 pb_message_set_to_defaults(fields, dest_struct);
496 return pb_decode_noinit(stream, fields, dest_struct);
501 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
504 if (!pb_decode_varint(stream, &value))
508 *dest = (int64_t)(~(value >> 1));
510 *dest = (int64_t)(value >> 1);
515 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
517 #ifdef __BIG_ENDIAN__
518 uint8_t *bytes = (uint8_t*)dest;
521 if (!pb_read(stream, lebytes, 4))
524 bytes[0] = lebytes[3];
525 bytes[1] = lebytes[2];
526 bytes[2] = lebytes[1];
527 bytes[3] = lebytes[0];
530 return pb_read(stream, (uint8_t*)dest, 4);
534 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
536 #ifdef __BIG_ENDIAN__
537 uint8_t *bytes = (uint8_t*)dest;
540 if (!pb_read(stream, lebytes, 8))
543 bytes[0] = lebytes[7];
544 bytes[1] = lebytes[6];
545 bytes[2] = lebytes[5];
546 bytes[3] = lebytes[4];
547 bytes[4] = lebytes[3];
548 bytes[5] = lebytes[2];
549 bytes[6] = lebytes[1];
550 bytes[7] = lebytes[0];
553 return pb_read(stream, (uint8_t*)dest, 8);
557 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
560 bool status = pb_decode_varint(stream, &value);
562 switch (field->data_size)
564 case 1: *(uint8_t*)dest = (uint8_t)value; break;
565 case 2: *(uint16_t*)dest = (uint16_t)value; break;
566 case 4: *(uint32_t*)dest = (uint32_t)value; break;
567 case 8: *(uint64_t*)dest = value; break;
568 default: PB_RETURN_ERROR(stream, "invalid data_size");
574 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
577 bool status = pb_decode_svarint(stream, &value);
579 switch (field->data_size)
581 case 4: *(int32_t*)dest = (int32_t)value; break;
582 case 8: *(int64_t*)dest = value; break;
583 default: PB_RETURN_ERROR(stream, "invalid data_size");
589 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
592 return pb_decode_fixed32(stream, dest);
595 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
598 return pb_decode_fixed64(stream, dest);
601 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
603 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
606 if (!pb_decode_varint32(stream, &temp))
610 /* Check length, noting the space taken by the size_t header. */
611 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
612 PB_RETURN_ERROR(stream, "bytes overflow");
614 return pb_read(stream, x->bytes, x->size);
617 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
621 if (!pb_decode_varint32(stream, &size))
624 /* Check length, noting the null terminator */
625 if (size + 1 > field->data_size)
626 PB_RETURN_ERROR(stream, "string overflow");
628 status = pb_read(stream, (uint8_t*)dest, size);
629 *((uint8_t*)dest + size) = 0;
633 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
636 pb_istream_t substream;
637 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
639 if (!pb_make_string_substream(stream, &substream))
642 if (field->ptr == NULL)
643 PB_RETURN_ERROR(stream, "invalid field descriptor");
645 /* New array entries need to be initialized, while required and optional
646 * submessages have already been initialized in the top-level pb_decode. */
647 if (PB_HTYPE(field->type) == PB_HTYPE_ARRAY)
648 status = pb_decode(&substream, submsg_fields, dest);
650 status = pb_decode_noinit(&substream, submsg_fields, dest);
652 pb_close_string_substream(stream, &substream);