1 /* pb_decode.c -- decode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
6 /* Use the GCC warn_unused_result attribute to check that all return values
7 * are propagated correctly. On other compilers and gcc before 3.4.0 just
8 * ignore the annotation.
10 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
13 #define checkreturn __attribute__((warn_unused_result))
16 #define NANOPB_INTERNALS
18 #include "pb_decode.h"
20 /**************************************
21 * Declarations internal to this file *
22 **************************************/
24 /* Iterator for pb_field_t list */
26 const pb_field_t *start; /* Start of the pb_field_t array */
27 const pb_field_t *pos; /* Current position of the iterator */
28 unsigned field_index; /* Zero-based index of the field. */
29 unsigned required_field_index; /* Zero-based index that counts only the required fields */
30 void *dest_struct; /* Pointer to the destination structure to decode to */
31 void *pData; /* Pointer where to store current field value */
32 void *pSize; /* Pointer where to store the size of current array field */
33 } pb_field_iterator_t;
35 typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
37 static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count);
38 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest);
39 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size);
40 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct);
41 static bool pb_field_next(pb_field_iterator_t *iter);
42 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag);
43 static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
44 static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
45 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
46 static bool checkreturn default_extension_decoder(pb_istream_t *stream, pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type);
47 static bool checkreturn decode_extension(pb_istream_t *stream, uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
48 static bool checkreturn find_extension_field(pb_field_iterator_t *iter);
49 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct);
51 /* --- Function pointers to field decoders ---
52 * Order in the array must match pb_action_t LTYPE numbering.
54 static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
66 /*******************************
67 * pb_istream_t implementation *
68 *******************************/
70 static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
72 uint8_t *source = (uint8_t*)stream->state;
73 stream->state = source + count;
84 bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
86 #ifndef PB_BUFFER_ONLY
87 if (buf == NULL && stream->callback != buf_read)
89 /* Skip input bytes */
93 if (!pb_read(stream, tmp, 16))
99 return pb_read(stream, tmp, count);
103 if (stream->bytes_left < count)
104 PB_RETURN_ERROR(stream, "end-of-stream");
106 #ifndef PB_BUFFER_ONLY
107 if (!stream->callback(stream, buf, count))
108 PB_RETURN_ERROR(stream, "io error");
110 if (!buf_read(stream, buf, count))
114 stream->bytes_left -= count;
118 pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
121 #ifdef PB_BUFFER_ONLY
122 stream.callback = NULL;
124 stream.callback = &buf_read;
127 stream.bytes_left = bufsize;
129 stream.errmsg = NULL;
134 /********************
136 ********************/
138 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
143 if (!pb_read(stream, &byte, 1))
148 /* Quick case, 1 byte value */
155 result = byte & 0x7F;
160 PB_RETURN_ERROR(stream, "varint overflow");
162 if (!pb_read(stream, &byte, 1))
165 result |= (uint32_t)(byte & 0x7F) << bitpos;
166 bitpos = (uint8_t)(bitpos + 7);
167 } while (byte & 0x80);
174 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
183 PB_RETURN_ERROR(stream, "varint overflow");
185 if (!pb_read(stream, &byte, 1))
188 result |= (uint64_t)(byte & 0x7F) << bitpos;
189 bitpos = (uint8_t)(bitpos + 7);
190 } while (byte & 0x80);
196 bool checkreturn pb_skip_varint(pb_istream_t *stream)
201 if (!pb_read(stream, &byte, 1))
203 } while (byte & 0x80);
207 bool checkreturn pb_skip_string(pb_istream_t *stream)
210 if (!pb_decode_varint32(stream, &length))
213 return pb_read(stream, NULL, length);
216 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
220 *wire_type = (pb_wire_type_t) 0;
223 if (!pb_decode_varint32(stream, &temp))
225 if (stream->bytes_left == 0)
233 *eof = true; /* Special feature: allow 0-terminated messages. */
238 *wire_type = (pb_wire_type_t)(temp & 7);
242 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
246 case PB_WT_VARINT: return pb_skip_varint(stream);
247 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
248 case PB_WT_STRING: return pb_skip_string(stream);
249 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
250 default: PB_RETURN_ERROR(stream, "invalid wire_type");
254 /* Read a raw value to buffer, for the purpose of passing it to callback as
255 * a substream. Size is maximum size on call, and actual size on return.
257 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
259 size_t max_size = *size;
267 if (*size > max_size) return false;
268 if (!pb_read(stream, buf, 1)) return false;
269 } while (*buf++ & 0x80);
274 return pb_read(stream, buf, 8);
278 return pb_read(stream, buf, 4);
280 default: PB_RETURN_ERROR(stream, "invalid wire_type");
284 /* Decode string length from stream and return a substream with limited length.
285 * Remember to close the substream using pb_close_string_substream().
287 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
290 if (!pb_decode_varint32(stream, &size))
293 *substream = *stream;
294 if (substream->bytes_left < size)
295 PB_RETURN_ERROR(stream, "parent stream too short");
297 substream->bytes_left = size;
298 stream->bytes_left -= size;
302 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
304 stream->state = substream->state;
307 stream->errmsg = substream->errmsg;
311 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
313 iter->start = iter->pos = fields;
314 iter->field_index = 0;
315 iter->required_field_index = 0;
316 iter->pData = (char*)dest_struct + iter->pos->data_offset;
317 iter->pSize = (char*)iter->pData + iter->pos->size_offset;
318 iter->dest_struct = dest_struct;
321 static bool pb_field_next(pb_field_iterator_t *iter)
323 bool notwrapped = true;
324 size_t prev_size = iter->pos->data_size;
326 if (PB_ATYPE(iter->pos->type) == PB_ATYPE_STATIC &&
327 PB_HTYPE(iter->pos->type) == PB_HTYPE_REPEATED)
329 prev_size *= iter->pos->array_size;
332 if (iter->pos->tag == 0)
333 return false; /* Only happens with empty message types */
335 if (PB_HTYPE(iter->pos->type) == PB_HTYPE_REQUIRED)
336 iter->required_field_index++;
340 if (iter->pos->tag == 0)
342 iter->pos = iter->start;
343 iter->field_index = 0;
344 iter->required_field_index = 0;
345 iter->pData = iter->dest_struct;
350 iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
351 iter->pSize = (char*)iter->pData + iter->pos->size_offset;
355 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
357 unsigned start = iter->field_index;
360 if (iter->pos->tag == tag &&
361 PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
366 } while (iter->field_index != start);
371 /*************************
372 * Decode a single field *
373 *************************/
375 static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
380 type = iter->pos->type;
381 func = PB_DECODERS[PB_LTYPE(type)];
383 switch (PB_HTYPE(type))
385 case PB_HTYPE_REQUIRED:
386 return func(stream, iter->pos, iter->pData);
388 case PB_HTYPE_OPTIONAL:
389 *(bool*)iter->pSize = true;
390 return func(stream, iter->pos, iter->pData);
392 case PB_HTYPE_REPEATED:
393 if (wire_type == PB_WT_STRING
394 && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
398 size_t *size = (size_t*)iter->pSize;
399 pb_istream_t substream;
400 if (!pb_make_string_substream(stream, &substream))
403 while (substream.bytes_left && *size < iter->pos->array_size)
405 void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
406 if (!func(&substream, iter->pos, pItem))
413 pb_close_string_substream(stream, &substream);
415 if (substream.bytes_left != 0)
416 PB_RETURN_ERROR(stream, "array overflow");
423 size_t *size = (size_t*)iter->pSize;
424 void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
425 if (*size >= iter->pos->array_size)
426 PB_RETURN_ERROR(stream, "array overflow");
429 return func(stream, iter->pos, pItem);
433 PB_RETURN_ERROR(stream, "invalid field type");
437 static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
439 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
441 #ifdef PB_OLD_CALLBACK_STYLE
442 void *arg = pCallback->arg;
444 void **arg = &(pCallback->arg);
447 if (pCallback->funcs.decode == NULL)
448 return pb_skip_field(stream, wire_type);
450 if (wire_type == PB_WT_STRING)
452 pb_istream_t substream;
454 if (!pb_make_string_substream(stream, &substream))
459 if (!pCallback->funcs.decode(&substream, iter->pos, arg))
460 PB_RETURN_ERROR(stream, "callback failed");
461 } while (substream.bytes_left);
463 pb_close_string_substream(stream, &substream);
468 /* Copy the single scalar value to stack.
469 * This is required so that we can limit the stream length,
470 * which in turn allows to use same callback for packed and
471 * not-packed fields. */
472 pb_istream_t substream;
474 size_t size = sizeof(buffer);
476 if (!read_raw_value(stream, wire_type, buffer, &size))
478 substream = pb_istream_from_buffer(buffer, size);
480 return pCallback->funcs.decode(&substream, iter->pos, arg);
484 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
486 switch (PB_ATYPE(iter->pos->type))
488 case PB_ATYPE_STATIC:
489 return decode_static_field(stream, wire_type, iter);
491 case PB_ATYPE_CALLBACK:
492 return decode_callback_field(stream, wire_type, iter);
495 PB_RETURN_ERROR(stream, "invalid field type");
499 /* Default handler for extension fields. Expects a pb_field_t structure
500 * in extension->type->arg. */
501 static bool checkreturn default_extension_decoder(pb_istream_t *stream,
502 pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type)
504 const pb_field_t *field = (const pb_field_t*)extension->type->arg;
505 pb_field_iterator_t iter;
508 if (field->tag != tag)
513 iter.field_index = 0;
514 iter.required_field_index = 0;
515 iter.dest_struct = extension->dest;
516 iter.pData = extension->dest;
519 return decode_field(stream, wire_type, &iter);
522 /* Try to decode an unknown field as an extension field. Tries each extension
523 * decoder in turn, until one of them handles the field or loop ends. */
524 static bool checkreturn decode_extension(pb_istream_t *stream,
525 uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
527 pb_extension_t *extension = *(pb_extension_t* const *)iter->pData;
528 size_t pos = stream->bytes_left;
530 while (extension && pos == stream->bytes_left)
533 if (extension->type->decode)
534 status = extension->type->decode(stream, extension, tag, wire_type);
536 status = default_extension_decoder(stream, extension, tag, wire_type);
541 extension = extension->next;
547 /* Step through the iterator until an extension field is found or until all
548 * entries have been checked. There can be only one extension field per
549 * message. Returns false if no extension field is found. */
550 static bool checkreturn find_extension_field(pb_field_iterator_t *iter)
552 unsigned start = iter->field_index;
555 if (PB_LTYPE(iter->pos->type) == PB_LTYPE_EXTENSION)
558 } while (iter->field_index != start);
563 /* Initialize message fields to default values, recursively */
564 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
566 pb_field_iterator_t iter;
567 pb_field_init(&iter, fields, dest_struct);
569 /* Initialize size/has fields and apply default values */
573 type = iter.pos->type;
575 if (iter.pos->tag == 0)
578 if (PB_ATYPE(type) == PB_ATYPE_STATIC)
580 /* Initialize the size field for optional/repeated fields to 0. */
581 if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
583 *(bool*)iter.pSize = false;
585 else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
587 *(size_t*)iter.pSize = 0;
588 continue; /* Array is empty, no need to initialize contents */
591 /* Initialize field contents to default value */
592 if (PB_LTYPE(iter.pos->type) == PB_LTYPE_SUBMESSAGE)
594 pb_message_set_to_defaults((const pb_field_t *) iter.pos->ptr, iter.pData);
596 else if (iter.pos->ptr != NULL)
598 memcpy(iter.pData, iter.pos->ptr, iter.pos->data_size);
602 memset(iter.pData, 0, iter.pos->data_size);
605 else if (PB_ATYPE(type) == PB_ATYPE_CALLBACK)
607 continue; /* Don't overwrite callback */
609 } while (pb_field_next(&iter));
612 /*********************
613 * Decode all fields *
614 *********************/
616 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
618 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
619 uint32_t extension_range_start = 0;
620 pb_field_iterator_t iter;
622 pb_field_init(&iter, fields, dest_struct);
624 while (stream->bytes_left)
627 pb_wire_type_t wire_type;
630 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
638 if (!pb_field_find(&iter, tag))
640 /* No match found, check if it matches an extension. */
641 if (tag >= extension_range_start)
643 if (!find_extension_field(&iter))
644 extension_range_start = (uint32_t)-1;
646 extension_range_start = iter.pos->tag;
648 if (tag >= extension_range_start)
650 size_t pos = stream->bytes_left;
652 if (!decode_extension(stream, tag, wire_type, &iter))
655 if (pos != stream->bytes_left)
657 /* The field was handled */
663 /* No match found, skip data */
664 if (!pb_skip_field(stream, wire_type))
669 if (PB_HTYPE(iter.pos->type) == PB_HTYPE_REQUIRED
670 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
672 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
675 if (!decode_field(stream, wire_type, &iter))
679 /* Check that all required fields were present. */
681 /* First figure out the number of required fields by
682 * seeking to the end of the field array. Usually we
683 * are already close to end after decoding.
685 unsigned req_field_count;
689 req_field_count = iter.required_field_index;
690 last_type = iter.pos->type;
691 } while (pb_field_next(&iter));
693 /* Fixup if last field was also required. */
694 if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED && iter.pos->tag)
697 /* Check the whole bytes */
698 for (i = 0; i < (req_field_count >> 3); i++)
700 if (fields_seen[i] != 0xFF)
701 PB_RETURN_ERROR(stream, "missing required field");
704 /* Check the remaining bits */
705 if (fields_seen[req_field_count >> 3] != (0xFF >> (8 - (req_field_count & 7))))
706 PB_RETURN_ERROR(stream, "missing required field");
712 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
714 pb_message_set_to_defaults(fields, dest_struct);
715 return pb_decode_noinit(stream, fields, dest_struct);
718 bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
720 pb_istream_t substream;
723 if (!pb_make_string_substream(stream, &substream))
726 status = pb_decode(&substream, fields, dest_struct);
727 pb_close_string_substream(stream, &substream);
733 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
736 if (!pb_decode_varint(stream, &value))
740 *dest = (int64_t)(~(value >> 1));
742 *dest = (int64_t)(value >> 1);
747 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
749 #ifdef __BIG_ENDIAN__
750 uint8_t *bytes = (uint8_t*)dest;
753 if (!pb_read(stream, lebytes, 4))
756 bytes[0] = lebytes[3];
757 bytes[1] = lebytes[2];
758 bytes[2] = lebytes[1];
759 bytes[3] = lebytes[0];
762 return pb_read(stream, (uint8_t*)dest, 4);
766 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
768 #ifdef __BIG_ENDIAN__
769 uint8_t *bytes = (uint8_t*)dest;
772 if (!pb_read(stream, lebytes, 8))
775 bytes[0] = lebytes[7];
776 bytes[1] = lebytes[6];
777 bytes[2] = lebytes[5];
778 bytes[3] = lebytes[4];
779 bytes[4] = lebytes[3];
780 bytes[5] = lebytes[2];
781 bytes[6] = lebytes[1];
782 bytes[7] = lebytes[0];
785 return pb_read(stream, (uint8_t*)dest, 8);
789 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
792 if (!pb_decode_varint(stream, &value))
795 switch (field->data_size)
797 case 1: *(uint8_t*)dest = (uint8_t)value; break;
798 case 2: *(uint16_t*)dest = (uint16_t)value; break;
799 case 4: *(uint32_t*)dest = (uint32_t)value; break;
800 case 8: *(uint64_t*)dest = value; break;
801 default: PB_RETURN_ERROR(stream, "invalid data_size");
807 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
810 if (!pb_decode_svarint(stream, &value))
813 switch (field->data_size)
815 case 4: *(int32_t*)dest = (int32_t)value; break;
816 case 8: *(int64_t*)dest = value; break;
817 default: PB_RETURN_ERROR(stream, "invalid data_size");
823 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
826 return pb_decode_fixed32(stream, dest);
829 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
832 return pb_decode_fixed64(stream, dest);
835 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
837 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
840 if (!pb_decode_varint32(stream, &temp))
844 /* Check length, noting the space taken by the size_t header. */
845 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
846 PB_RETURN_ERROR(stream, "bytes overflow");
848 return pb_read(stream, x->bytes, x->size);
851 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
855 if (!pb_decode_varint32(stream, &size))
858 /* Check length, noting the null terminator */
859 if (size + 1 > field->data_size)
860 PB_RETURN_ERROR(stream, "string overflow");
862 status = pb_read(stream, (uint8_t*)dest, size);
863 *((uint8_t*)dest + size) = 0;
867 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
870 pb_istream_t substream;
871 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
873 if (!pb_make_string_substream(stream, &substream))
876 if (field->ptr == NULL)
877 PB_RETURN_ERROR(stream, "invalid field descriptor");
879 /* New array entries need to be initialized, while required and optional
880 * submessages have already been initialized in the top-level pb_decode. */
881 if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
882 status = pb_decode(&substream, submsg_fields, dest);
884 status = pb_decode_noinit(&substream, submsg_fields, dest);
886 pb_close_string_substream(stream, &substream);