109 lines
3.5 KiB
C
109 lines
3.5 KiB
C
/***
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* Helper to derived protobuf objects
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*/
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#include <stdint.h>
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#include <string.h>
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#include "varint.h"
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#include "protobuf.h"
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/***
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* encode a string into the buffer
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* @param field_number the field number
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* @param field_type the field type
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* @param incoming the string value
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* @param buffer the pointer to where to place the encoded value
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* @param max_buffer_length the buffer length remaining
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* @param bytes_written the number of bytes written
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* @returns true(1) on success
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*/
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int protobuf_encode_string(int field_number, enum WireType field_type, const char* incoming, unsigned char* buffer,
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size_t max_buffer_length, size_t* bytes_written) {
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// push the field number and wire type together
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unsigned int field_no = field_number << 3;
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unsigned long long field = field_no | field_type;
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size_t bytes_processed;
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*bytes_written = 0;
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// field type & number
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varint_encode(field, buffer, max_buffer_length, &bytes_processed);
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*bytes_written += bytes_processed;
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// field size
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varint_encode(strlen(incoming), &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_processed);
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*bytes_written += bytes_processed;
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// field value
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memcpy(&buffer[*bytes_written], incoming, strlen(incoming));
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*bytes_written += strlen(incoming);
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return 1;
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}
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/***
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* encode a varint into the buffer
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* @param field_number the field number
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* @param field_type the field type
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* @param incoming the value
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* @param buffer the pointer to where to place the encoded value
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* @param max_buffer_length the buffer length remaining
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* @param bytes_written the number of bytes written
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* @returns true(1) on success
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*/
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int protobuf_encode_varint(int field_number, enum WireType field_type, unsigned long long incoming, unsigned char* buffer,
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size_t max_buffer_length, size_t* bytes_written) {
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// push the field number and wire type together
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unsigned int field_no = field_number << 3;
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unsigned long long field = field_no | field_type;
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size_t bytes_processed;
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// field type & number
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varint_encode(field, buffer, max_buffer_length, &bytes_processed);
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*bytes_written += bytes_processed;
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// field value
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varint_encode(incoming, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_processed);
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*bytes_written += bytes_processed;
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return 1;
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}
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/**
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* Pull a string from the protobuf buffer
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* @param the buffer, positioned at the field size
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* @param buffer_length the buffer length
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* @param results the results (NOTE: will allocate memory)
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* @param bytes_read the number of bytes read
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* @returns true(1) on success
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*/
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int protobuf_decode_string(const unsigned char* buffer, size_t buffer_length, char** results, size_t* bytes_read) {
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size_t pos = 0;
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// grab the field size
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int length = varint_decode(&buffer[pos], buffer_length - pos, bytes_read);
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pos += *bytes_read;
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// allocate memory
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*results = malloc(sizeof(char) * length);
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if ((*results) == NULL)
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return 0;
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// copy the string
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memcpy((*results), &buffer[pos], length);
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pos += length;
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*bytes_read = pos;
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return 1;
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}
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/***
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* retrieve field number and field type from current buffer at position 0
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* @param buffer the incoming buffer
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* @param buffer_length the length of the buffer
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* @param field_no the resultant field number
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* @param field_type the field type
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* @param bytes_read the number of bytes read from the buffer
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*/
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int protobuf_decode_field_and_type(const unsigned char* buffer, int buffer_length, int *field_no, enum WireType *field_type, size_t* bytes_read) {
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unsigned long long field = varint_decode(buffer, buffer_length, bytes_read);
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*field_no = field >> 3;
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*field_type = field | *field_no;
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return 1;
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}
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