Function sctp_compute_hmac

freebsd/netinet/sctp_auth.c:1056–1088

* computes the requested HMAC using a key struct (which may be modified if * the keylen exceeds the HMAC block len). */

 * the keylen exceeds the HMAC block len).
 */
uint32_t
sctp_compute_hmac(uint16_t hmac_algo, sctp_key_t *key, uint8_t *text,
    uint32_t textlen, uint8_t *digest)
{
	uint32_t digestlen;
	uint32_t blocklen;
	sctp_hash_context_t ctx;
	uint8_t temp[SCTP_AUTH_DIGEST_LEN_MAX];

	/* sanity check */
	if ((key == NULL) || (text == NULL) || (textlen == 0) ||
	    (digest == NULL)) {
		/* can't do HMAC with empty key or text or digest store */
		return (0);
	}
	/* validate the hmac algo and get the digest length */
	digestlen = sctp_get_hmac_digest_len(hmac_algo);
	if (digestlen == 0)
		return (0);

	/* hash the key if it is longer than the hash block size */
	blocklen = sctp_get_hmac_block_len(hmac_algo);
	if (key->keylen > blocklen) {
		sctp_hmac_init(hmac_algo, &ctx);
		sctp_hmac_update(hmac_algo, &ctx, key->key, key->keylen);
		sctp_hmac_final(hmac_algo, &ctx, temp);
		/* save the hashed key as the new key */
		key->keylen = digestlen;
		memcpy(key->key, temp, key->keylen);
	}
	return (sctp_hmac(hmac_algo, key->key, key->keylen, text, textlen,
	    digest));
}

/* mbuf version */
uint32_t