c-ipfs/cid/cid.c
2017-09-04 13:33:56 -05:00

320 lines
8.8 KiB
C

/**
* Content ID
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ipfs/cid/cid.h"
#include "libp2p/crypto/encoding/base58.h"
#include "ipfs/multibase/multibase.h"
#include "mh/hashes.h"
#include "mh/multihash.h"
#include "varint.h"
enum WireType ipfs_cid_message_fields[] = { WIRETYPE_VARINT, WIRETYPE_VARINT, WIRETYPE_LENGTH_DELIMITED };
size_t ipfs_cid_protobuf_encode_size(const struct Cid* cid) {
if (cid != NULL)
return 11+12+cid->hash_length+11;
return 0;
}
int ipfs_cid_protobuf_encode(const struct Cid* cid, unsigned char* buffer, size_t buffer_length, size_t* bytes_written) {
size_t bytes_used;
*bytes_written = 0;
int retVal = 0;
if (cid != NULL) {
retVal = protobuf_encode_varint(1, ipfs_cid_message_fields[0], cid->version, buffer, buffer_length, &bytes_used);
if (retVal == 0)
return 0;
*bytes_written += bytes_used;
retVal = protobuf_encode_varint(2, ipfs_cid_message_fields[1], cid->codec, &buffer[*bytes_written], buffer_length - (*bytes_written), &bytes_used);
if (retVal == 0)
return 0;
*bytes_written += bytes_used;
retVal = protobuf_encode_length_delimited(3, ipfs_cid_message_fields[2], (char*)cid->hash, cid->hash_length, &buffer[*bytes_written], buffer_length - (*bytes_written), &bytes_used);
if (retVal == 0)
return 0;
*bytes_written += bytes_used;
}
return 1;
}
int ipfs_cid_protobuf_decode(unsigned char* buffer, size_t buffer_length, struct Cid** output) {
// short cut for nulls
if (buffer_length == 0) {
*output = NULL;
return 1;
}
size_t pos = 0;
int version = 0;
unsigned char* hash;
size_t hash_length;
char codec = 0;
int retVal = 0;
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) {
return 0;
}
pos += bytes_read;
switch(field_no) {
case (1):
version = varint_decode(&buffer[pos], buffer_length - pos, &bytes_read);
pos += bytes_read;
break;
case (2):
codec = varint_decode(&buffer[pos], buffer_length - pos, &bytes_read);
pos += bytes_read;
break;
case (3):
retVal = protobuf_decode_length_delimited(&buffer[pos], buffer_length - pos, (char**)&hash, &hash_length, &bytes_read);
if (retVal == 0)
return 0;
pos += bytes_read;
break;
}
}
*output = ipfs_cid_new(version, hash, hash_length, codec);
retVal = *output != NULL;
free(hash);
return retVal;
}
/**
* Create a new CID based on the given hash
* @param version the version
* @param hash the multihash
* @param hash_length the length of the multihash in bytes
* @param codec the codec to be used (NOTE: For version 0, this should be CID_PROTOBUF)
* @returns the new Cid or NULL if there was a problem
*/
struct Cid* ipfs_cid_new(int version, const unsigned char* hash, size_t hash_length, const char codec) {
struct Cid* cid = (struct Cid*) malloc(sizeof(struct Cid));
if (cid != NULL) {
cid->hash_length = hash_length;
if (hash_length == 0 || hash == NULL) {
cid->hash = NULL;
} else {
cid->hash = (unsigned char*) malloc(sizeof(unsigned char) * hash_length);
if (cid->hash == NULL) {
free(cid);
return NULL;
}
memcpy(cid->hash, hash, hash_length);
}
// assign other values
cid->version = version;
cid->codec = codec;
}
return cid;
}
/***
* Free the resources from a Cid
* @param cid the struct
* @returns 1
*/
int ipfs_cid_free(struct Cid* cid) {
if (cid != NULL) {
if (cid->hash != NULL) {
free(cid->hash);
cid->hash = NULL;
}
free(cid);
}
return 1;
}
/***
* Make a copy of a Cid
* @param original the original
* @returns a copy of the original
*/
struct Cid* ipfs_cid_copy(const struct Cid* original) {
struct Cid* copy = (struct Cid*) malloc(sizeof(struct Cid));
if (copy != NULL) {
copy->codec = original->codec;
copy->version = original->version;
copy->hash_length = original->hash_length;
copy->hash = (unsigned char*) malloc(original->hash_length);
memcpy(copy->hash, original->hash, original->hash_length);
}
return copy;
}
/***
* Fill a Cid struct based on a base 58 encoded multihash
* @param incoming the string
* @param incoming_size the size of the string
* @cid the Cid struct to fill
* @return true(1) on success
*/
int ipfs_cid_decode_hash_from_base58(const unsigned char* incoming, size_t incoming_length, struct Cid** cid) {
int retVal = 0;
if (incoming_length < 2)
return 0;
// is this a sha_256 multihash?
if (incoming_length == 46 && incoming[0] == 'Q' && incoming[1] == 'm') {
size_t hash_length = libp2p_crypto_encoding_base58_decode_size(incoming_length);
unsigned char hash[hash_length];
unsigned char* ptr = hash;
retVal = libp2p_crypto_encoding_base58_decode(incoming, incoming_length, &ptr, &hash_length);
if (retVal == 0)
return 0;
// now we have the hash, build the object
*cid = ipfs_cid_new(0, &hash[2], hash_length - 2, CID_DAG_PROTOBUF);
return *cid != NULL;
}
// TODO: finish this
/*
// it wasn't a sha_256 multihash, try to decode it using multibase
size_t buffer_size = multibase_decode_size(incoming_length);
if (buffer_size == 0)
return 0;
unsigned char buffer[buffer_size];
memset(buffer, 0, buffer_size);
retVal = multibase_decode(incoming, incoming_length, buffer, buffer_size, &buffer_size);
if (retVal == 0)
return 0;
return cid_cast(buffer, buffer_size, cid);
*/
return 0;
}
/**
* Turn a cid hash into a base 58
* @param hash the hash to work with
* @param hash_length the length of the existing hash
* @param buffer where to put the results
* @param max_buffer_length the maximum space reserved for the results
* @returns true(1) on success
*/
int ipfs_cid_hash_to_base58(const unsigned char* hash, size_t hash_length, unsigned char* buffer, size_t max_buffer_length) {
int multihash_len = hash_length + 2;
unsigned char multihash[multihash_len];
if (mh_new(multihash, MH_H_SHA2_256, hash, hash_length) < 0) {
return 0;
}
// base58
size_t b58_size = libp2p_crypto_encoding_base58_encode_size(multihash_len);
if (b58_size > max_buffer_length) // buffer too small
return 0;
if( libp2p_crypto_encoding_base58_encode(multihash, multihash_len, &buffer, &max_buffer_length) == 0) {
return 0;
}
return 1;
}
/***
* Turn the hash of this CID into a c string
* @param cid the cid
* @param result a place to allocate and store the string
* @returns a pointer to the string (*result) or NULL if there was a problem
*/
char* ipfs_cid_to_string(const struct Cid* cid, char **result) {
size_t str_len = libp2p_crypto_encoding_base58_encode_size(cid->hash_length) + 1;
char *str = (char*) malloc(str_len);
*result = str;
if (str != NULL) {
if (!libp2p_crypto_encoding_base58_encode(cid->hash, cid->hash_length, (unsigned char**)&str, &str_len)) {
free(str);
str = NULL;
}
}
return str;
}
/***
* Turn a multibase decoded string of bytes into a Cid struct
* @param incoming the multibase decoded array
* @param incoming_size the size of the array
* @param cid the Cid structure to fill
*/
int ipfs_cid_cast(const unsigned char* incoming, size_t incoming_size, struct Cid* cid) {
if (incoming_size == 34 && incoming[0] == 18 && incoming[1] == 32) {
// this is a multihash
cid->hash_length = mh_multihash_length(incoming, incoming_size);
cid->codec = CID_DAG_PROTOBUF;
cid->version = 0;
mh_multihash_digest(incoming, incoming_size, &cid->hash, &cid->hash_length);
return 1;
}
// This is not a multihash. Perhaps it is using varints. Try to peel the information out of the bytes.
// first the version
int pos = 0;
size_t num_bytes = 0;
cid->version = varint_decode(&incoming[pos], incoming_size - pos, &num_bytes);
if (num_bytes == 0 || cid->version > 1 || cid->version < 0)
return 0;
pos = num_bytes;
// now the codec
uint32_t codec = 0;
codec = varint_decode(&incoming[pos], incoming_size - pos, &num_bytes);
if (num_bytes == 0)
return 0;
cid->codec = codec;
pos += num_bytes;
// now what is left
cid->hash_length = incoming_size - pos;
cid->hash = (unsigned char*)(&incoming[pos]);
return 1;
}
/**
* Compare two cids
*
* TODO: find a common denominator between versions and codecs so that
* we can compare apples to apples.
*
* @param a side A
* @param b side B
* @returns < 0 if side A is greater, > 0 if side B is greater, or 0 if equal
*/
int ipfs_cid_compare(const struct Cid* a, const struct Cid* b) {
if (a == NULL && b == NULL)
return 0;
if (a != NULL && b == NULL)
return -1;
if (a == NULL && b != NULL)
return 1;
if (a->version != b->version) {
return b->version - a->version;
}
if (a->codec != b->codec) {
return ((int)b->codec - (int)a->codec);
}
if (a->hash_length != b->hash_length) {
return b->hash_length - a->hash_length;
}
for(size_t i = 0; i < a->hash_length; i++) {
if (a->hash[i] != b->hash[i]) {
return ((int)b->hash[i] - (int)a->hash[i]);
}
}
return 0;
}