c-ipfs/cid/cid.c

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/**
* 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/multihash.h"
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#include "multiaddr/varint.h"
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/**
* 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)
* @param cid where to put the results
* @returns true(1) on success
*/
int cid_new(int version, unsigned char* hash, size_t hash_length, const char codec, struct Cid* cid) {
// allocate memory
cid->hash = malloc(sizeof(unsigned char) * hash_length);
if (cid->hash == NULL)
return 0;
// assign values
cid->version = version;
cid->codec = codec;
memcpy(cid->hash, hash, hash_length);
cid->hash_length = hash_length;
return 1;
}
/***
* Free the resources from a Cid
* @param cid the struct
* @returns 1
*/
int cid_free(struct Cid* cid) {
if (cid->hash != NULL)
free(cid->hash);
return 1;
}
/***
* Fill a Cid struct based on a base 58 encoded string
* @param incoming the string
* @param incoming_size the size of the string
* @cid the Cid struct to fill
* @return true(1) on success
*/
int cid_decode_from_string(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
return cid_new(0, hash, hash_length, CID_PROTOBUF, cid);
}
// 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 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 cid_cast(unsigned char* incoming, size_t incoming_size, struct Cid* cid) {
// this is a multihash
if (incoming_size == 34 && incoming[0] == 18 && incoming[1] == 32) {
cid->hash_length = mh_multihash_length(incoming, incoming_size);
cid->codec = CID_PROTOBUF;
cid->version = 0;
mh_multihash_digest(incoming, incoming_size, &cid->hash, &cid->hash_length);
return 1;
}
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// This is not a multihash. Perhaps it is using varints. Try to peel the information out of the bytes.
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// first the version
int pos = 0, retVal = 0;
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size_t num_bytes = 0;
num_bytes = uvarint_decode32(&incoming[pos], incoming_size - pos, &cid->version);
if (num_bytes < 0 || cid->version > 1 || cid->version < 0)
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return 0;
pos = num_bytes;
// now the codec
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uint32_t codec = 0;
num_bytes = uvarint_decode32(&incoming[pos], incoming_size - pos, &codec);
if (num_bytes < 0)
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return 0;
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cid->codec = codec;
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pos += num_bytes;
// now what is left
cid->hash_length = incoming_size - pos;
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cid->hash = &incoming[pos];
return 1;
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}