97 lines
2.1 KiB
C
97 lines
2.1 KiB
C
#include "mh/multihash.h"
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#include "mh/hashes.h"
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#include "mh/errors.h"
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#include "mh/generic.h"
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#include <string.h>
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#include <stdlib.h>
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#define VARINT_MASK (1 << 7)
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static int check_len(size_t len) {
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if (len < 1)
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return MH_E_TOO_SHORT;
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else if (len >= 128)
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return MH_E_TOO_LONG;
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return MH_E_NO_ERROR;
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}
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static int check_multihash(const unsigned char mh[], size_t len) {
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int err;
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if (len < 3)
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return MH_E_TOO_SHORT;
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if (mh[0] & VARINT_MASK) {
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// This value is a varint, but there are currently no supported
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// values that require more than a single byte to represent.
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return MH_E_VARINT_NOT_SUPPORTED;
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} else if (mh[1] & VARINT_MASK) {
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return MH_E_VARINT_NOT_SUPPORTED;
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}
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err = check_len(mh[1]);
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if (err)
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return err;
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return 0;
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}
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// returns hash code or error (which is < 0)
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int mh_multihash_hash(const unsigned char *mh, size_t len) {
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int err = check_multihash(multihash, len);
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if (err)
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return err;
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return (int) mh[0];
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}
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// returns length of multihash or error (which is < 0)
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int mh_multihash_length(const unsigned char *mh, size_t len) {
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int err = check_multihash(multihash, len);
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if (err)
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return err;
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return (int) mh[1];
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}
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// gives access to raw digest inside multihash buffer
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// returns 0 or negative error
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int mh_multihash_digest(unsigned char *multihash, size_t len, unsigned char **digest,
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size_t *digest_len) {
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int err = check_multihash(multihash, len);
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if (err)
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return err;
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(*digest_len) = (size_t) mh_multihash_length(multihash, len);
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(*digest) = multihash + 2; // Always true without varint
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return 0;
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}
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int mh_new_length(int code, size_t hash_len) {
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// right now there is no varint support
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// so length required is 2 + hash_len
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UNUSED(code);
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return 2 + hash_len;
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}
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int mh_new(unsigned char *buffer, int code, const unsigned char *digest,
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size_t digest_len) {
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if (code & VARINT_MASK)
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return MH_E_VARINT_NOT_SUPPORTED;
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if (digest_len > 127)
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return MH_E_DIGSET_TOO_LONG;
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buffer[0] = (unsigned char) ((unsigned int) code) & 255;
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buffer[1] = (unsigned char) digest_len;
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memcpy(buffer + 2, digest, digest_len);
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return 0;
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}
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