c-ipfs/blocks/block.c
2016-12-14 12:24:44 -05:00

163 lines
4.5 KiB
C

/**
* The implementation of methods around IPFS blocks
*/
#include <stdlib.h>
#include <string.h>
#include "libp2p/crypto/sha256.h"
#include "ipfs/blocks/block.h"
#include "ipfs/cid/cid.h"
/***
* The protobuf functions
*/
// protobuf fields: data & data_length cid
enum WireType ipfs_block_message_fields[] = { WIRETYPE_LENGTH_DELIMITED, WIRETYPE_LENGTH_DELIMITED};
/**
* Determine the approximate size of an encoded block
* @param block the block to measure
* @returns the approximate size needed to encode the protobuf
*/
size_t ipfs_blocks_block_protobuf_encode_size(const struct Block* block) {
return 22 + ipfs_cid_protobuf_encode_size(block->cid) + block->data_length;
}
/**
* Encode the Block into protobuf format
* @param block the block to encode
* @param buffer the buffer to fill
* @param max_buffer_size the max size of the buffer
* @param bytes_written the number of bytes used
* @returns true(1) on success
*/
int ipfs_blocks_block_protobuf_encode(const struct Block* block, unsigned char* buffer, size_t max_buffer_length, size_t* bytes_written) {
// data & data_size
size_t bytes_used = 0;
*bytes_written = 0;
int retVal = 0;
retVal = protobuf_encode_length_delimited(1, ipfs_block_message_fields[0], (char*)block->data, block->data_length, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_used);
*bytes_written += bytes_used;
// cid
size_t cid_size = ipfs_cid_protobuf_encode_size(block->cid);
unsigned char cid[cid_size];
retVal = ipfs_cid_protobuf_encode(block->cid, cid, cid_size, &cid_size);
if (retVal == 0)
return 0;
retVal = protobuf_encode_length_delimited(2, ipfs_block_message_fields[1], (char*)cid, cid_size, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_used);
if (retVal == 0)
return 0;
*bytes_written += bytes_used;
return 1;
}
/***
* Decode from a protobuf stream into a Block struct
* @param buffer the buffer to pull from
* @param buffer_length the length of the buffer
* @param block the block to fill
* @returns true(1) on success
*/
int ipfs_blocks_block_protobuf_decode(const unsigned char* buffer, const size_t buffer_length, struct Block** block) {
size_t pos = 0;
int retVal = 0;
unsigned char* temp_buffer = NULL;
size_t temp_size;
if (ipfs_blocks_block_new(block) == 0)
goto exit;
while(pos < buffer_length) {
size_t bytes_read = 0;
int field_no;
enum WireType field_type;
if (protobuf_decode_field_and_type(&buffer[pos], buffer_length, &field_no, &field_type, &bytes_read) == 0) {
goto exit;
}
pos += bytes_read;
switch(field_no) {
case (1): // data
if (protobuf_decode_length_delimited(&buffer[pos], buffer_length - pos, (char**)&((*block)->data), &((*block)->data_length), &bytes_read) == 0)
goto exit;
pos += bytes_read;
break;
case (2): // cid
if (protobuf_decode_length_delimited(&buffer[pos], buffer_length - pos, (char**)&temp_buffer, &temp_size, &bytes_read) == 0)
goto exit;
pos += bytes_read;
if (ipfs_cid_protobuf_decode(temp_buffer, temp_size, &((*block)->cid)) == 0)
goto exit;
free(temp_buffer);
temp_buffer = NULL;
break;
}
}
retVal = 1;
exit:
if (retVal == 0) {
ipfs_blocks_block_free(*block);
}
if (temp_buffer != NULL)
free(temp_buffer);
return retVal;
}
/***
* Create a new block based on the incoming data
* @param data the data to base the block on
* @param data_size the length of the data array
* @param block a pointer to the struct Block that will be created
* @returns true(1) on success
*/
int ipfs_blocks_block_new(struct Block** block) {
// allocate memory for structure
(*block) = (struct Block*)malloc(sizeof(struct Block));
if ((*block) == NULL)
return 0;
(*block)->data = NULL;
(*block)->data_length = 0;
return 1;
}
int ipfs_blocks_block_add_data(const unsigned char* data, size_t data_size, struct Block* block) {
// cid
unsigned char hash[32];
if (libp2p_crypto_hashing_sha256(data, data_size, &hash[0]) == 0) {
return 0;
}
if (ipfs_cid_new(0, hash, 32, CID_PROTOBUF, &(block->cid)) == 0) {
return 0;
}
block->data_length = data_size;
block->data = malloc(sizeof(unsigned char) * data_size);
if ( block->data == NULL) {
ipfs_cid_free(block->cid);
return 0;
}
memcpy( block->data, data, data_size);
return 1;
}
/***
* Free resources used by the creation of a block
* @param block the block to free
* @returns true(1) on success
*/
int ipfs_blocks_block_free(struct Block* block) {
ipfs_cid_free(block->cid);
if (block->data != NULL)
free(block->data);
free(block);
return 1;
}