c-protobuf/protobuf.c

155 lines
4.9 KiB
C

/***
* Helper to derived protobuf objects
*/
#include <stdint.h>
#include <string.h>
#include "varint.h"
#include "protobuf.h"
int protobuf_encode_length_delimited(int field_number, enum WireType field_type, const char* incoming, size_t incoming_length,
unsigned char* buffer, size_t max_buffer_length, size_t* bytes_written)
{
// push the field number and wire type together
unsigned int field_no = field_number << 3;
unsigned long long field = field_no | field_type;
size_t bytes_processed = 0;
*bytes_written = 0;
// field type & number
varint_encode(field, buffer, max_buffer_length, &bytes_processed);
*bytes_written += bytes_processed;
// field size
varint_encode(incoming_length, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_processed);
*bytes_written += bytes_processed;
// field value
if (incoming_length > 0) {
memcpy(&buffer[*bytes_written], incoming, incoming_length);
*bytes_written += incoming_length;
}
return 1;
}
int protobuf_decode_length_delimited(const unsigned char* buffer, size_t buffer_length, char** results, size_t *results_length, size_t* bytes_read) {
size_t pos = 0;
*bytes_read = 0;
// grab the field size
size_t field_size = varint_decode(&buffer[pos], buffer_length - pos, bytes_read);
pos += *bytes_read;
// allocate memory
*results = malloc(sizeof(char) * field_size);
if ((*results) == NULL)
return 0;
memset(*results, 0, field_size);
// copy the bytes
memcpy( *results, &buffer[pos], field_size);
pos += field_size;
// set return values
*bytes_read = pos;
*results_length = field_size;
return 1;
}
/***
* encode a string into the buffer
* @param field_number the field number
* @param field_type the field type
* @param incoming the string value
* @param buffer the pointer to where to place the encoded value
* @param max_buffer_length the buffer length remaining
* @param bytes_written the number of bytes written
* @returns true(1) on success
*/
int protobuf_encode_string(int field_number, enum WireType field_type, const char* incoming, unsigned char* buffer,
size_t max_buffer_length, size_t* bytes_written) {
return protobuf_encode_length_delimited(field_number, field_type, incoming, strlen(incoming), buffer, max_buffer_length, bytes_written);
}
/***
* encode a varint into the buffer
* @param field_number the field number
* @param field_type the field type
* @param incoming the value
* @param buffer the pointer to where to place the encoded value
* @param max_buffer_length the buffer length remaining
* @param bytes_written the number of bytes written
* @returns true(1) on success
*/
int protobuf_encode_varint(int field_number, enum WireType field_type, unsigned long long incoming, unsigned char* buffer,
size_t max_buffer_length, size_t* bytes_written) {
*bytes_written = 0;
// push the field number and wire type together
unsigned int field_no = field_number << 3;
unsigned long long field = field_no | field_type;
size_t bytes_processed;
// field type & number
varint_encode(field, buffer, max_buffer_length, &bytes_processed);
*bytes_written += bytes_processed;
// field value
varint_encode(incoming, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_processed);
*bytes_written += bytes_processed;
return 1;
}
int protobuf_decode_varint(const unsigned char* buffer, size_t buffer_length, unsigned long long* results, size_t* bytes_read) {
*results = varint_decode(buffer, buffer_length, bytes_read);
return 1;
}
/**
* Pull a string from the protobuf buffer
* @param the buffer, positioned at the field size
* @param buffer_length the buffer length
* @param results the results (NOTE: will allocate memory)
* @param bytes_read the number of bytes read
* @returns true(1) on success
*/
int protobuf_decode_string(const unsigned char* buffer, size_t buffer_length, char** results, size_t* bytes_read) {
size_t pos = 0;
*bytes_read = 0;
// grab the field size
int length = varint_decode(&buffer[pos], buffer_length - pos, bytes_read);
pos += *bytes_read;
*bytes_read += length;
// allocate memory (if neccesary)
if (length > 0) {
*results = malloc(sizeof(char) * length + 1);
if ((*results) == NULL)
return 0;
memset(*results, 0, length+1);
// copy the string
memcpy((*results), &buffer[pos], length);
// don't forget the null
(*results)[length] = 0;
}
return 1;
}
/***
* retrieve field number and field type from current buffer at position 0
* @param buffer the incoming buffer
* @param buffer_length the length of the buffer
* @param field_no the resultant field number
* @param field_type the field type
* @param bytes_read the number of bytes read from the buffer
*/
int protobuf_decode_field_and_type(const unsigned char* buffer, int buffer_length, int *field_no, enum WireType *field_type, size_t* bytes_read) {
*bytes_read = 0;
unsigned long long field = varint_decode(buffer, buffer_length, bytes_read);
*field_no = field >> 3;
*field_type = field - (*field_no << 3);
return 1;
}