| /* pb_decode.c -- decode a protobuf using minimal resources |
| * |
| * 2011 Petteri Aimonen <jpa@kapsi.fi> |
| */ |
| |
| |
| #ifdef __GNUC__ |
| /* Verify that we remember to check all return values for proper error propagation */ |
| #define checkreturn __attribute__((warn_unused_result)) |
| #else |
| #define checkreturn |
| #endif |
| |
| #include "pb.h" |
| #include "pb_decode.h" |
| #include <string.h> |
| |
| typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn; |
| |
| /* --- Function pointers to field decoders --- |
| * Order in the array must match pb_action_t LTYPE numbering. |
| */ |
| static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = { |
| &pb_dec_varint, |
| &pb_dec_svarint, |
| &pb_dec_fixed32, |
| &pb_dec_fixed64, |
| |
| &pb_dec_bytes, |
| &pb_dec_string, |
| &pb_dec_submessage |
| }; |
| |
| /************** |
| * pb_istream * |
| **************/ |
| |
| bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count) |
| { |
| if (stream->bytes_left < count) |
| return false; |
| |
| if (!stream->callback(stream, buf, count)) |
| return false; |
| |
| stream->bytes_left -= count; |
| return true; |
| } |
| |
| static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count) |
| { |
| uint8_t *source = (uint8_t*)stream->state; |
| |
| if (buf != NULL) |
| memcpy(buf, source, count); |
| |
| stream->state = source + count; |
| return true; |
| } |
| |
| pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize) |
| { |
| pb_istream_t stream; |
| stream.callback = &buf_read; |
| stream.state = buf; |
| stream.bytes_left = bufsize; |
| return stream; |
| } |
| |
| /******************** |
| * Helper functions * |
| ********************/ |
| |
| static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest) |
| { |
| uint64_t temp; |
| bool status = pb_decode_varint(stream, &temp); |
| *dest = temp; |
| return status; |
| } |
| |
| bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest) |
| { |
| uint8_t byte; |
| uint8_t bitpos = 0; |
| *dest = 0; |
| |
| while (bitpos < 64 && pb_read(stream, &byte, 1)) |
| { |
| *dest |= (uint64_t)(byte & 0x7F) << bitpos; |
| bitpos += 7; |
| |
| if (!(byte & 0x80)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| bool checkreturn pb_skip_varint(pb_istream_t *stream) |
| { |
| uint8_t byte; |
| do |
| { |
| if (!pb_read(stream, &byte, 1)) |
| return false; |
| } while (byte & 0x80); |
| return true; |
| } |
| |
| bool checkreturn pb_skip_string(pb_istream_t *stream) |
| { |
| uint32_t length; |
| if (!pb_decode_varint32(stream, &length)) |
| return false; |
| |
| return pb_read(stream, NULL, length); |
| } |
| |
| /* Currently the wire type related stuff is kept hidden from |
| * callbacks. They shouldn't need it. It's better for performance |
| * to just assume the correct type and fail safely on corrupt message. |
| */ |
| |
| static bool checkreturn skip(pb_istream_t *stream, pb_wire_type_t wire_type) |
| { |
| switch (wire_type) |
| { |
| case PB_WT_VARINT: return pb_skip_varint(stream); |
| case PB_WT_64BIT: return pb_read(stream, NULL, 8); |
| case PB_WT_STRING: return pb_skip_string(stream); |
| case PB_WT_32BIT: return pb_read(stream, NULL, 4); |
| default: return false; |
| } |
| } |
| |
| /* Read a raw value to buffer, for the purpose of passing it to callback as |
| * a substream. Size is maximum size on call, and actual size on return. |
| */ |
| static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size) |
| { |
| size_t max_size = *size; |
| switch (wire_type) |
| { |
| case PB_WT_VARINT: |
| *size = 0; |
| do |
| { |
| (*size)++; |
| if (*size > max_size) return false; |
| if (!pb_read(stream, buf, 1)) return false; |
| } while (*buf++ & 0x80); |
| return true; |
| |
| case PB_WT_64BIT: |
| *size = 8; |
| return pb_read(stream, buf, 8); |
| |
| case PB_WT_32BIT: |
| *size = 4; |
| return pb_read(stream, buf, 4); |
| |
| default: return false; |
| } |
| } |
| |
| /* Decode string length from stream and return a substream with limited length. |
| * Before disposing the substream, remember to copy the substream->state back |
| * to stream->state. |
| */ |
| static bool checkreturn make_string_substream(pb_istream_t *stream, pb_istream_t *substream) |
| { |
| uint32_t size; |
| if (!pb_decode_varint32(stream, &size)) |
| return false; |
| |
| *substream = *stream; |
| if (substream->bytes_left < size) |
| return false; |
| |
| substream->bytes_left = size; |
| stream->bytes_left -= size; |
| return true; |
| } |
| |
| /* Iterator for pb_field_t list */ |
| typedef struct { |
| const pb_field_t *start; |
| const pb_field_t *current; |
| int field_index; |
| void *dest_struct; |
| void *pData; |
| void *pSize; |
| } pb_field_iterator_t; |
| |
| static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct) |
| { |
| iter->start = iter->current = fields; |
| iter->field_index = 0; |
| iter->pData = (char*)dest_struct + iter->current->data_offset; |
| iter->pSize = (char*)iter->pData + iter->current->size_offset; |
| iter->dest_struct = dest_struct; |
| } |
| |
| static bool pb_field_next(pb_field_iterator_t *iter) |
| { |
| bool notwrapped = true; |
| size_t prev_size = iter->current->data_size; |
| |
| if (PB_HTYPE(iter->current->type) == PB_HTYPE_ARRAY) |
| prev_size *= iter->current->array_size; |
| |
| iter->current++; |
| iter->field_index++; |
| if (iter->current->tag == 0) |
| { |
| iter->current = iter->start; |
| iter->field_index = 0; |
| iter->pData = iter->dest_struct; |
| prev_size = 0; |
| notwrapped = false; |
| } |
| |
| iter->pData = (char*)iter->pData + prev_size + iter->current->data_offset; |
| iter->pSize = (char*)iter->pData + iter->current->size_offset; |
| return notwrapped; |
| } |
| |
| static bool checkreturn pb_field_find(pb_field_iterator_t *iter, int tag) |
| { |
| int start = iter->field_index; |
| |
| do { |
| if (iter->current->tag == tag) |
| return true; |
| pb_field_next(iter); |
| } while (iter->field_index != start); |
| |
| return false; |
| } |
| |
| /************************* |
| * Decode a single field * |
| *************************/ |
| |
| static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter) |
| { |
| pb_decoder_t func = PB_DECODERS[PB_LTYPE(iter->current->type)]; |
| |
| switch (PB_HTYPE(iter->current->type)) |
| { |
| case PB_HTYPE_REQUIRED: |
| return func(stream, iter->current, iter->pData); |
| |
| case PB_HTYPE_OPTIONAL: |
| *(bool*)iter->pSize = true; |
| return func(stream, iter->current, iter->pData); |
| |
| case PB_HTYPE_ARRAY: |
| if (wire_type == PB_WT_STRING |
| && PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE) |
| { |
| /* Packed array */ |
| size_t *size = (size_t*)iter->pSize; |
| pb_istream_t substream; |
| if (!make_string_substream(stream, &substream)) |
| return false; |
| |
| while (substream.bytes_left && *size < iter->current->array_size) |
| { |
| void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size); |
| if (!func(&substream, iter->current, pItem)) |
| return false; |
| (*size)++; |
| } |
| return (substream.bytes_left == 0); |
| } |
| else |
| { |
| /* Repeated field */ |
| size_t *size = (size_t*)iter->pSize; |
| void *pItem = (uint8_t*)iter->pData + iter->current->data_size * (*size); |
| if (*size >= iter->current->array_size) |
| return false; |
| |
| (*size)++; |
| return func(stream, iter->current, pItem); |
| } |
| |
| case PB_HTYPE_CALLBACK: |
| { |
| pb_callback_t *pCallback = (pb_callback_t*)iter->pData; |
| |
| if (pCallback->funcs.decode == NULL) |
| return skip(stream, wire_type); |
| |
| if (wire_type == PB_WT_STRING) |
| { |
| pb_istream_t substream; |
| |
| if (!make_string_substream(stream, &substream)) |
| return false; |
| |
| while (substream.bytes_left) |
| { |
| if (!pCallback->funcs.decode(&substream, iter->current, pCallback->arg)) |
| return false; |
| } |
| |
| stream->state = substream.state; |
| return true; |
| } |
| else |
| { |
| /* Copy the single scalar value to stack. |
| * This is required so that we can limit the stream length, |
| * which in turn allows to use same callback for packed and |
| * not-packed fields. */ |
| pb_istream_t substream; |
| uint8_t buffer[10]; |
| size_t size = sizeof(buffer); |
| |
| if (!read_raw_value(stream, wire_type, buffer, &size)) |
| return false; |
| substream = pb_istream_from_buffer(buffer, size); |
| |
| return pCallback->funcs.decode(&substream, iter->current, pCallback->arg); |
| } |
| } |
| |
| default: |
| return false; |
| } |
| } |
| |
| /* Initialize message fields to default values, recursively */ |
| static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct) |
| { |
| pb_field_iterator_t iter; |
| pb_field_init(&iter, fields, dest_struct); |
| |
| /* Initialize size/has fields and apply default values */ |
| do |
| { |
| if (iter.current->tag == 0) |
| continue; |
| |
| /* Initialize the size field for optional/repeated fields to 0. */ |
| if (PB_HTYPE(iter.current->type) == PB_HTYPE_OPTIONAL) |
| { |
| *(bool*)iter.pSize = false; |
| } |
| else if (PB_HTYPE(iter.current->type) == PB_HTYPE_ARRAY) |
| { |
| *(size_t*)iter.pSize = 0; |
| continue; /* Array is empty, no need to initialize contents */ |
| } |
| |
| /* Initialize field contents to default value */ |
| if (PB_HTYPE(iter.current->type) == PB_HTYPE_CALLBACK) |
| { |
| continue; /* Don't overwrite callback */ |
| } |
| else if (PB_LTYPE(iter.current->type) == PB_LTYPE_SUBMESSAGE) |
| { |
| pb_message_set_to_defaults(iter.current->ptr, iter.pData); |
| } |
| else if (iter.current->ptr != NULL) |
| { |
| memcpy(iter.pData, iter.current->ptr, iter.current->data_size); |
| } |
| else |
| { |
| memset(iter.pData, 0, iter.current->data_size); |
| } |
| } while (pb_field_next(&iter)); |
| } |
| |
| /********************* |
| * Decode all fields * |
| *********************/ |
| |
| bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct) |
| { |
| uint32_t fields_seen = 0; /* Used to check for required fields */ |
| pb_field_iterator_t iter; |
| int i; |
| |
| pb_message_set_to_defaults(fields, dest_struct); |
| |
| pb_field_init(&iter, fields, dest_struct); |
| |
| while (stream->bytes_left) |
| { |
| uint32_t temp; |
| int tag; |
| pb_wire_type_t wire_type; |
| if (!pb_decode_varint32(stream, &temp)) |
| { |
| if (stream->bytes_left == 0) |
| break; /* It was EOF */ |
| else |
| return false; /* It was error */ |
| } |
| |
| if (temp == 0) |
| break; /* Special feature: allow 0-terminated messages. */ |
| |
| tag = temp >> 3; |
| wire_type = (pb_wire_type_t)(temp & 7); |
| |
| if (!pb_field_find(&iter, tag)) |
| { |
| /* No match found, skip data */ |
| if (!skip(stream, wire_type)) |
| return false; |
| continue; |
| } |
| |
| fields_seen |= 1 << (iter.field_index & 31); |
| |
| if (!decode_field(stream, wire_type, &iter)) |
| return false; |
| } |
| |
| /* Check that all required fields (mod 31) were present. */ |
| for (i = 0; fields[i].tag != 0; i++) |
| { |
| if (PB_HTYPE(fields[i].type) == PB_HTYPE_REQUIRED && |
| !(fields_seen & (1 << (i & 31)))) |
| { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| /* Field decoders */ |
| |
| /* Copy destsize bytes from src so that values are casted properly. |
| * On little endian machine, copy first n bytes of src |
| * On big endian machine, copy last n bytes of src |
| * srcsize must always be larger than destsize |
| */ |
| static void endian_copy(void *dest, void *src, size_t destsize, size_t srcsize) |
| { |
| #ifdef __BIG_ENDIAN__ |
| memcpy(dest, (char*)src + (srcsize - destsize), destsize); |
| #else |
| memcpy(dest, src, destsize); |
| #endif |
| } |
| |
| bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| uint64_t temp; |
| bool status = pb_decode_varint(stream, &temp); |
| endian_copy(dest, &temp, field->data_size, sizeof(temp)); |
| return status; |
| } |
| |
| bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| uint64_t temp; |
| bool status = pb_decode_varint(stream, &temp); |
| temp = (temp >> 1) ^ -(int64_t)(temp & 1); |
| endian_copy(dest, &temp, field->data_size, sizeof(temp)); |
| return status; |
| } |
| |
| bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| #ifdef __BIG_ENDIAN__ |
| uint8_t bytes[4] = {0}; |
| bool status = pb_read(stream, bytes, 4); |
| uint8_t bebytes[4] = {bytes[3], bytes[2], bytes[1], bytes[0]}; |
| memcpy(dest, bebytes, 4); |
| return status; |
| #else |
| return pb_read(stream, (uint8_t*)dest, 4); |
| #endif |
| } |
| |
| bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| #ifdef __BIG_ENDIAN__ |
| uint8_t bytes[8] = {0}; |
| bool status = pb_read(stream, bytes, 8); |
| uint8_t bebytes[8] = {bytes[7], bytes[6], bytes[5], bytes[4], |
| bytes[3], bytes[2], bytes[1], bytes[0]}; |
| memcpy(dest, bebytes, 8); |
| return status; |
| #else |
| return pb_read(stream, (uint8_t*)dest, 8); |
| #endif |
| } |
| |
| bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| pb_bytes_array_t *x = (pb_bytes_array_t*)dest; |
| |
| uint32_t temp; |
| if (!pb_decode_varint32(stream, &temp)) |
| return false; |
| x->size = temp; |
| |
| if (x->size > field->data_size) |
| return false; |
| |
| return pb_read(stream, x->bytes, x->size); |
| } |
| |
| bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| uint32_t size; |
| bool status; |
| if (!pb_decode_varint32(stream, &size)) |
| return false; |
| |
| if (size > field->data_size - 1) |
| return false; |
| |
| status = pb_read(stream, (uint8_t*)dest, size); |
| *((uint8_t*)dest + size) = 0; |
| return status; |
| } |
| |
| bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest) |
| { |
| bool status; |
| pb_istream_t substream; |
| |
| if (!make_string_substream(stream, &substream)) |
| return false; |
| |
| if (field->ptr == NULL) |
| return false; |
| |
| status = pb_decode(&substream, (pb_field_t*)field->ptr, dest); |
| stream->state = substream.state; |
| return status; |
| } |