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;
90 static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
93 bool status = pb_decode_varint(stream, &temp);
94 *dest = (uint32_t)temp;
98 bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
104 while (bitpos < 64 && pb_read(stream, &byte, 1))
106 *dest |= (uint64_t)(byte & 0x7F) << bitpos;
113 PB_RETURN_ERROR(stream, "varint overflow");
116 bool checkreturn pb_skip_varint(pb_istream_t *stream)
121 if (!pb_read(stream, &byte, 1))
123 } while (byte & 0x80);
127 bool checkreturn pb_skip_string(pb_istream_t *stream)
130 if (!pb_decode_varint32(stream, &length))
133 return pb_read(stream, NULL, length);
136 bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
140 *wire_type = (pb_wire_type_t) 0;
143 if (!pb_decode_varint32(stream, &temp))
145 if (stream->bytes_left == 0)
153 *eof = true; /* Special feature: allow 0-terminated messages. */
158 *wire_type = (pb_wire_type_t)(temp & 7);
162 bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
166 case PB_WT_VARINT: return pb_skip_varint(stream);
167 case PB_WT_64BIT: return pb_read(stream, NULL, 8);
168 case PB_WT_STRING: return pb_skip_string(stream);
169 case PB_WT_32BIT: return pb_read(stream, NULL, 4);
170 default: PB_RETURN_ERROR(stream, "invalid wire_type");
174 /* Read a raw value to buffer, for the purpose of passing it to callback as
175 * a substream. Size is maximum size on call, and actual size on return.
177 static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
179 size_t max_size = *size;
187 if (*size > max_size) return false;
188 if (!pb_read(stream, buf, 1)) return false;
189 } while (*buf++ & 0x80);
194 return pb_read(stream, buf, 8);
198 return pb_read(stream, buf, 4);
200 default: PB_RETURN_ERROR(stream, "invalid wire_type");
204 /* Decode string length from stream and return a substream with limited length.
205 * Remember to close the substream using pb_close_string_substream().
207 bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
210 if (!pb_decode_varint32(stream, &size))
213 *substream = *stream;
214 if (substream->bytes_left < size)
215 PB_RETURN_ERROR(stream, "parent stream too short");
217 substream->bytes_left = size;
218 stream->bytes_left -= size;
222 void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
224 stream->state = substream->state;
227 /* Iterator for pb_field_t list */
229 const pb_field_t *start; /* Start of the pb_field_t array */
230 const pb_field_t *current; /* Current position of the iterator */
231 int field_index; /* Zero-based index of the field. */
232 int required_field_index; /* Zero-based index that counts only the required fields */
233 void *dest_struct; /* Pointer to the destination structure to decode to */
234 void *pData; /* Pointer where to store current field value */
235 void *pSize; /* Pointer where to store the size of current array field */
236 } pb_field_iterator_t;
238 static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
240 iter->start = iter->current = fields;
241 iter->field_index = 0;
242 iter->required_field_index = 0;
243 iter->pData = (char*)dest_struct + iter->current->data_offset;
244 iter->pSize = (char*)iter->pData + iter->current->size_offset;
245 iter->dest_struct = dest_struct;
248 static bool pb_field_next(pb_field_iterator_t *iter)
250 bool notwrapped = true;
251 size_t prev_size = iter->current->data_size;
253 if (PB_HTYPE(iter->current->type) == PB_HTYPE_ARRAY)
254 prev_size *= iter->current->array_size;
256 if (PB_HTYPE(iter->current->type) == PB_HTYPE_REQUIRED)
257 iter->required_field_index++;
261 if (iter->current->tag == 0)
263 iter->current = iter->start;
264 iter->field_index = 0;
265 iter->required_field_index = 0;
266 iter->pData = iter->dest_struct;
271 iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset;
272 iter->pSize = (char*)iter->pData + iter->current->size_offset;
276 static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
278 int start = iter->field_index;
281 if (iter->current->tag == tag)
284 } while (iter->field_index != start);
289 /*************************
290 * Decode a single field *
291 *************************/
293 static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
295 pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)];
297 switch (PB_HTYPE(iter->current->type))
299 case PB_HTYPE_REQUIRED:
300 return func(stream, iter->current, iter->pData);
302 case PB_HTYPE_OPTIONAL:
303 *(bool*)iter->pSize = true;
304 return func(stream, iter->current, iter->pData);
307 if (wire_type == PB_WT_STRING
308 && PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
312 size_t *size = (size_t*)iter->pSize;
313 pb_istream_t substream;
314 if (!pb_make_string_substream(stream, &substream))
317 while (substream.bytes_left && *size < iter->current->array_size)
319 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
320 if (!func(&substream, iter->current, pItem))
324 status = (substream.bytes_left == 0);
325 pb_close_string_substream(stream, &substream);
331 size_t *size = (size_t*)iter->pSize;
332 void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size);
333 if (*size >= iter->current->array_size)
334 PB_RETURN_ERROR(stream, "array overflow");
337 return func(stream, iter->current, pItem);
340 case PB_HTYPE_CALLBACK:
342 pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
344 if (pCallback->funcs.decode == NULL)
345 return pb_skip_field(stream, wire_type);
347 if (wire_type == PB_WT_STRING)
349 pb_istream_t substream;
351 if (!pb_make_string_substream(stream, &substream))
354 while (substream.bytes_left)
356 if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg))
357 PB_RETURN_ERROR(stream, "callback failed");
360 pb_close_string_substream(stream, &substream);
365 /* Copy the single scalar value to stack.
366 * This is required so that we can limit the stream length,
367 * which in turn allows to use same callback for packed and
368 * not-packed fields. */
369 pb_istream_t substream;
371 size_t size = sizeof(buffer);
373 if (!read_raw_value(stream, wire_type, buffer, &size))
375 substream = pb_istream_from_buffer(buffer, size);
377 return pCallback->funcs.decode(&substream, iter->current, pCallback->arg);
382 PB_RETURN_ERROR(stream, "invalid field type");
386 /* Initialize message fields to default values, recursively */
387 static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
389 pb_field_iterator_t iter;
390 pb_field_init(&iter, fields, dest_struct);
392 /* Initialize size/has fields and apply default values */
395 if (iter.current->tag == 0)
398 /* Initialize the size field for optional/repeated fields to 0. */
399 if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL)
401 *(bool*)iter.pSize = false;
403 else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY)
405 *(size_t*)iter.pSize = 0;
406 continue; /* Array is empty, no need to initialize contents */
409 /* Initialize field contents to default value */
410 if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK)
412 continue; /* Don't overwrite callback */
414 else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE)
416 pb_message_set_to_defaults((const pb_field_t *) iter.current->ptr, iter.pData);
418 else if (iter.current->ptr != NULL)
420 memcpy(iter.pData, iter.current->ptr, iter.current->data_size);
424 memset(iter.pData, 0, iter.current->data_size);
426 } while (pb_field_next(&iter));
429 /*********************
430 * Decode all fields *
431 *********************/
433 bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
435 uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0}; /* Used to check for required fields */
436 pb_field_iterator_t iter;
438 pb_field_init(&iter, fields, dest_struct);
440 while (stream->bytes_left)
443 pb_wire_type_t wire_type;
446 if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
454 if (!pb_field_find(&iter, tag))
456 /* No match found, skip data */
457 if (!pb_skip_field(stream, wire_type))
462 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED
463 && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
465 fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
468 if (!decode_field(stream, wire_type, &iter))
472 /* Check that all required fields were present. */
473 pb_field_init(&iter, fields, dest_struct);
475 if (PB_HTYPE(iter.current->type) == PB_HTYPE_REQUIRED &&
476 iter.required_field_index < PB_MAX_REQUIRED_FIELDS &&
477 !(fields_seen[iter.required_field_index >> 3] & (1 << (iter.required_field_index & 7))))
479 PB_RETURN_ERROR(stream, "missing required field");
481 } while (pb_field_next(&iter));
486 bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
488 pb_message_set_to_defaults(fields, dest_struct);
489 return pb_decode_noinit(stream, fields, dest_struct);
494 bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
497 if (!pb_decode_varint(stream, &value))
501 *dest = (int64_t)(~(value >> 1));
503 *dest = (int64_t)(value >> 1);
508 bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
510 #ifdef __BIG_ENDIAN__
511 uint8_t *bytes = (uint8_t*)dest;
514 if (!pb_read(stream, lebytes, 4))
517 bytes[0] = lebytes[3];
518 bytes[1] = lebytes[2];
519 bytes[2] = lebytes[1];
520 bytes[3] = lebytes[0];
523 return pb_read(stream, (uint8_t*)dest, 4);
527 bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
529 #ifdef __BIG_ENDIAN__
530 uint8_t *bytes = (uint8_t*)dest;
533 if (!pb_read(stream, lebytes, 8))
536 bytes[0] = lebytes[7];
537 bytes[1] = lebytes[6];
538 bytes[2] = lebytes[5];
539 bytes[3] = lebytes[4];
540 bytes[4] = lebytes[3];
541 bytes[5] = lebytes[2];
542 bytes[6] = lebytes[1];
543 bytes[7] = lebytes[0];
546 return pb_read(stream, (uint8_t*)dest, 8);
550 bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
553 bool status = pb_decode_varint(stream, &value);
555 switch (field->data_size)
557 case 1: *(uint8_t*)dest = (uint8_t)value; break;
558 case 2: *(uint16_t*)dest = (uint16_t)value; break;
559 case 4: *(uint32_t*)dest = (uint32_t)value; break;
560 case 8: *(uint64_t*)dest = value; break;
561 default: PB_RETURN_ERROR(stream, "invalid data_size");
567 bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
570 bool status = pb_decode_svarint(stream, &value);
572 switch (field->data_size)
574 case 4: *(int32_t*)dest = (int32_t)value; break;
575 case 8: *(int64_t*)dest = value; break;
576 default: PB_RETURN_ERROR(stream, "invalid data_size");
582 bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
585 return pb_decode_fixed32(stream, dest);
588 bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
591 return pb_decode_fixed64(stream, dest);
594 bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
596 pb_bytes_array_t *x = (pb_bytes_array_t*)dest;
599 if (!pb_decode_varint32(stream, &temp))
603 /* Check length, noting the space taken by the size_t header. */
604 if (x->size > field->data_size - offsetof(pb_bytes_array_t, bytes))
605 PB_RETURN_ERROR(stream, "bytes overflow");
607 return pb_read(stream, x->bytes, x->size);
610 bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
614 if (!pb_decode_varint32(stream, &size))
617 /* Check length, noting the null terminator */
618 if (size + 1 > field->data_size)
619 PB_RETURN_ERROR(stream, "string overflow");
621 status = pb_read(stream, (uint8_t*)dest, size);
622 *((uint8_t*)dest + size) = 0;
626 bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
629 pb_istream_t substream;
630 const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
632 if (!pb_make_string_substream(stream, &substream))
635 if (field->ptr == NULL)
636 PB_RETURN_ERROR(stream, "invalid field descriptor");
638 /* New array entries need to be initialized, while required and optional
639 * submessages have already been initialized in the top-level pb_decode. */
640 if (PB_HTYPE(field->type) == PB_HTYPE_ARRAY)
641 status = pb_decode(&substream, submsg_fields, dest);
643 status = pb_decode_noinit(&substream, submsg_fields, dest);
645 pb_close_string_substream(stream, &substream);