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;
42 stream->state = source + count;
53 bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
55 #ifndef PB_BUFFER_ONLY
56 if (buf == NULL && stream->callback != buf_read)
58 /* Skip input bytes */
62 if (!pb_read(stream, tmp, 16))
68 return pb_read(stream, tmp, count);
72 if (stream->bytes_left < count)
73 PB_RETURN_ERROR(stream, "end-of-stream");
75 #ifndef PB_BUFFER_ONLY
76 if (!stream->callback(stream, buf, count))
77 PB_RETURN_ERROR(stream, "io error");
79 if (!buf_read(stream, buf, count))
83 stream->bytes_left -= count;
87 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
91 stream.callback = NULL;
93 stream.callback = &buf_read;
96 stream.bytes_left = bufsize;
103 /********************
105 ********************/
107 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
112 if (!pb_read(stream, &byte, 1))
117 /* Quick case, 1 byte value */
124 result = byte & 0x7F;
129 PB_RETURN_ERROR(stream, "varint overflow");
131 if (!pb_read(stream, &byte, 1))
134 result |= (uint32_t)(byte & 0x7F) << bitpos;
135 bitpos = (uint8_t)(bitpos + 7);
136 } while (byte & 0x80);
143 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
152 PB_RETURN_ERROR(stream, "varint overflow");
154 if (!pb_read(stream, &byte, 1))
157 result |= (uint64_t)(byte & 0x7F) << bitpos;
158 bitpos = (uint8_t)(bitpos + 7);
159 } while (byte & 0x80);
165 bool checkreturn pb_skip_varint(pb_istream_t *stream)
170 if (!pb_read(stream, &byte, 1))
172 } while (byte & 0x80);
176 bool checkreturn pb_skip_string(pb_istream_t *stream)
179 if (!pb_decode_varint32(stream, &length))
182 return pb_read(stream, NULL, length);
185 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
189 *wire_type = (pb_wire_type_t) 0;
192 if (!pb_decode_varint32(stream, &temp))
194 if (stream->bytes_left == 0)
202 *eof = true; /* Special feature: allow 0-terminated messages. */
207 *wire_type = (pb_wire_type_t)(temp & 7);
211 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
215 case PB_WT_VARINT: return pb_skip_varint(stream);
216 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
217 case PB_WT_STRING: return pb_skip_string(stream);
218 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
219 default: PB_RETURN_ERROR(stream, "invalid wire_type");
223 /* Read a raw value to buffer, for the purpose of passing it to callback as
224 * a substream. Size is maximum size on call, and actual size on return.
226 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
228 size_t max_size = *size;
236 if (*size > max_size) return false;
237 if (!pb_read(stream, buf, 1)) return false;
238 } while (*buf++ & 0x80);
243 return pb_read(stream, buf, 8);
247 return pb_read(stream, buf, 4);
249 default: PB_RETURN_ERROR(stream, "invalid wire_type");
253 /* Decode string length from stream and return a substream with limited length.
254 * Remember to close the substream using pb_close_string_substream().
256 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
259 if (!pb_decode_varint32(stream, &size))
262 *substream = *stream;
263 if (substream->bytes_left < size)
264 PB_RETURN_ERROR(stream, "parent stream too short");
266 substream->bytes_left = size;
267 stream->bytes_left -= size;
271 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
273 stream->state = substream->state;
276 stream->errmsg = substream->errmsg;
280 /* Iterator for pb_field_t list */
282 const pb_field_t *start; /* Start of the pb_field_t array */
283 const pb_field_t *current; /* Current position of the iterator */
284 unsigned field_index; /* Zero-based index of the field. */
285 unsigned required_field_index; /* Zero-based index that counts only the required fields */
286 void *dest_struct; /* Pointer to the destination structure to decode to */
287 void *pData; /* Pointer where to store current field value */
288 void *pSize; /* Pointer where to store the size of current array field */
289 } pb_field_iterator_t;
291 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
293 iter->start = iter->current = fields;
294 iter->field_index = 0;
295 iter->required_field_index = 0;
296 iter->pData = (char*)dest_struct + iter->current->data_offset;
297 iter->pSize = (char*)iter->pData + iter->current->size_offset;
298 iter->dest_struct = dest_struct;
301 static bool pb_field_next(pb_field_iterator_t *iter)
303 bool notwrapped = true;
304 size_t prev_size = iter->current->data_size;
306 if (PB_HTYPE(iter->current->type) == PB_HTYPE_ARRAY)
307 prev_size *= iter->current->array_size;
309 if (PB_HTYPE(iter->current->type) == PB_HTYPE_REQUIRED)
310 iter->required_field_index++;
314 if (iter->current->tag == 0)
316 iter->current = iter->start;
317 iter->field_index = 0;
318 iter->required_field_index = 0;
319 iter->pData = iter->dest_struct;
324 iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset;
325 iter->pSize = (char*)iter->pData + iter->current->size_offset;
329 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
331 unsigned start = iter->field_index;
334 if (iter->current->tag == tag)
337 } while (iter->field_index != start);
342 /*************************
343 * Decode a single field *
344 *************************/
346 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
348 pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)];
350 switch (PB_HTYPE(iter->current->type))
352 case PB_HTYPE_REQUIRED:
353 return func(stream, iter->current, iter->pData);
355 case PB_HTYPE_OPTIONAL:
356 *(bool*)iter->pSize = true;
357 return func(stream, iter->current, iter->pData);
360 if (wire_type == PB_WT_STRING
361 && PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
365 size_t *size = (size_t*)iter->pSize;
366 pb_istream_t substream;
367 if (!pb_make_string_substream(stream, &substream))
370 while (substream.bytes_left && *size < iter->current->array_size)
372 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
373 if (!func(&substream, iter->current, pItem))
377 status = (substream.bytes_left == 0);
378 pb_close_string_substream(stream, &substream);
384 size_t *size = (size_t*)iter->pSize;
385 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
386 if (*size >= iter->current->array_size)
387 PB_RETURN_ERROR(stream, "array overflow");
390 return func(stream, iter->current, pItem);
393 case PB_HTYPE_CALLBACK:
395 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
397 if (pCallback->funcs.decode == NULL)
398 return pb_skip_field(stream, wire_type);
400 if (wire_type == PB_WT_STRING)
402 pb_istream_t substream;
404 if (!pb_make_string_substream(stream, &substream))
407 while (substream.bytes_left)
409 if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
410 PB_RETURN_ERROR(stream, "callback failed");
413 pb_close_string_substream(stream, &substream);
418 /* Copy the single scalar value to stack.
419 * This is required so that we can limit the stream length,
420 * which in turn allows to use same callback for packed and
421 * not-packed fields. */
422 pb_istream_t substream;
424 size_t size = sizeof(buffer);
426 if (!read_raw_value(stream, wire_type, buffer, &size))
428 substream = pb_istream_from_buffer(buffer, size);
430 return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
435 PB_RETURN_ERROR(stream, "invalid field type");
439 /* Initialize message fields to default values, recursively */
440 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
442 pb_field_iterator_t iter;
443 pb_field_init(&iter, fields, dest_struct);
445 /* Initialize size/has fields and apply default values */
448 if (iter.current->tag == 0)
451 /* Initialize the size field for optional/repeated fields to 0. */
452 if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
454 *(bool*)iter.pSize = false;
456 else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
458 *(size_t*)iter.pSize = 0;
459 continue; /* Array is empty, no need to initialize contents */
462 /* Initialize field contents to default value */
463 if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
465 continue; /* Don't overwrite callback */
467 else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
469 pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
471 else if (iter.current->ptr != NULL)
473 memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
477 memset(iter.pData, 0, iter.current->data_size);
479 } while (pb_field_next(&iter));
482 /*********************
483 * Decode all fields *
484 *********************/
486 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
488 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
489 pb_field_iterator_t iter;
491 pb_field_init(&iter, fields, dest_struct);
493 while (stream->bytes_left)
496 pb_wire_type_t wire_type;
499 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
507 if (!pb_field_find(&iter, tag))
509 /* No match found, skip data */
510 if (!pb_skip_field(stream, wire_type))
515 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
516 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
518 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
521 if (!decode_field(stream, wire_type, &iter))
525 /* Check that all required fields were present. */
527 /* First figure out the number of required fields by
528 * seeking to the end of the field array. Usually we
529 * are already close to end after decoding.
531 unsigned req_field_count;
535 req_field_count = iter.required_field_index;
536 last_type = iter.current->type;
537 } while (pb_field_next(&iter));
539 /* Fixup if last field was also required. */
540 if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED)
543 /* Check the whole bytes */
544 for (i = 0; i < (req_field_count >> 3); i++)
546 if (fields_seen[i] != 0xFF)
547 PB_RETURN_ERROR(stream, "missing required field");
550 /* Check the remaining bits */
551 if (fields_seen[req_field_count >> 3] != (0xFF >> (8 - (req_field_count & 7))))
552 PB_RETURN_ERROR(stream, "missing required field");
558 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
560 pb_message_set_to_defaults(fields, dest_struct);
561 return pb_decode_noinit(stream, fields, dest_struct);
566 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
569 if (!pb_decode_varint(stream, &value))
573 *dest = (int64_t)(~(value >> 1));
575 *dest = (int64_t)(value >> 1);
580 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
582 #ifdef __BIG_ENDIAN__
583 uint8_t *bytes = (uint8_t*)dest;
586 if (!pb_read(stream, lebytes, 4))
589 bytes[0] = lebytes[3];
590 bytes[1] = lebytes[2];
591 bytes[2] = lebytes[1];
592 bytes[3] = lebytes[0];
595 return pb_read(stream, (uint8_t*)dest, 4);
599 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
601 #ifdef __BIG_ENDIAN__
602 uint8_t *bytes = (uint8_t*)dest;
605 if (!pb_read(stream, lebytes, 8))
608 bytes[0] = lebytes[7];
609 bytes[1] = lebytes[6];
610 bytes[2] = lebytes[5];
611 bytes[3] = lebytes[4];
612 bytes[4] = lebytes[3];
613 bytes[5] = lebytes[2];
614 bytes[6] = lebytes[1];
615 bytes[7] = lebytes[0];
618 return pb_read(stream, (uint8_t*)dest, 8);
622 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
625 bool status = pb_decode_varint(stream, &value);
627 switch (field->data_size)
629 case 1: *(uint8_t*)dest = (uint8_t)value; break;
630 case 2: *(uint16_t*)dest = (uint16_t)value; break;
631 case 4: *(uint32_t*)dest = (uint32_t)value; break;
632 case 8: *(uint64_t*)dest = value; break;
633 default: PB_RETURN_ERROR(stream, "invalid data_size");
639 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
642 bool status = pb_decode_svarint(stream, &value);
644 switch (field->data_size)
646 case 4: *(int32_t*)dest = (int32_t)value; break;
647 case 8: *(int64_t*)dest = value; break;
648 default: PB_RETURN_ERROR(stream, "invalid data_size");
654 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
657 return pb_decode_fixed32(stream, dest);
660 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
663 return pb_decode_fixed64(stream, dest);
666 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
668 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
671 if (!pb_decode_varint32(stream, &temp))
675 /* Check length, noting the space taken by the size_t header. */
676 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
677 PB_RETURN_ERROR(stream, "bytes overflow");
679 return pb_read(stream, x->bytes, x->size);
682 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
686 if (!pb_decode_varint32(stream, &size))
689 /* Check length, noting the null terminator */
690 if (size + 1 > field->data_size)
691 PB_RETURN_ERROR(stream, "string overflow");
693 status = pb_read(stream, (uint8_t*)dest, size);
694 *((uint8_t*)dest + size) = 0;
698 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
701 pb_istream_t substream;
702 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
704 if (!pb_make_string_substream(stream, &substream))
707 if (field->ptr == NULL)
708 PB_RETURN_ERROR(stream, "invalid field descriptor");
710 /* New array entries need to be initialized, while required and optional
711 * submessages have already been initialized in the top-level pb_decode. */
712 if (PB_HTYPE(field->type) == PB_HTYPE_ARRAY)
713 status = pb_decode(&substream, submsg_fields, dest);
715 status = pb_decode_noinit(&substream, submsg_fields, dest);
717 pb_close_string_substream(stream, &substream);