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/* Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*!
* \file
*
* \addtogroup tsig
*
* \brief Low-level TSIG signing API.
*
* Example:
*
* ~~~~~ {.c}
*
* int result;
*
* dnssec_binary_t *covered = // ... ;
* dnssec_binary_t *signature = // ... ;
*
* // convert algorithm from textual representation
* dnssec_tsig_algorithm_t algorithm;
* algorithm = dnssec_tsig_algorithm_from_name("hmac-sha256");
* assert(algorithm == DNSSEC_TSIG_HMAC_SHA256);
*
* // get shared key
* dnssec_binary_t key = {
* .size = 4,
* .data = (uint8_t *) { 0x11, 0x22, 0x33, 0x44 }
* };
*
* // create computation context
* dnssec_tsig_ctx_t *ctx;
* result = dnssec_tsig_new(&ctx, algorithm, &key);
* if (result != DNSSEC_EOK) {
* return result;
* }
*
* // add data to be covered by the signature
* dnssec_tsig_add(ctx, covered);
*
* // compute the expected signature (MAC)
* size_t size = dnssec_tsig_size(ctx);
* dnssec_binary_t expected_signature = { 0 };
* result = dnssec_binary_alloc(&expected_signature, size);
* if (result != DNSSEC_EOK) {
* dnssec_tsig_free(ctx);
* return result;
* }
* dnssec_tsig_write(ctx, &expected_signature);
*
* // compare the signatures
* if (dnssec_binary_cmp(signature, &expected_signature) == 0) {
* // valid signature
* } else {
* // invalid signature
* }
*
* // cleanup
* dnssec_binary_free(&expected_signature);
* dnssec_tsig_free(ctx);
*
* ~~~~~
*
* @{
*/
#pragma once
#include <stdint.h>
#include <libdnssec/binary.h>
/*!
* TSIG algorithms.
*
* \note The numeric values are library specific.
*/
typedef enum dnssec_tsig_algorithm {
DNSSEC_TSIG_UNKNOWN = 0,
DNSSEC_TSIG_HMAC_MD5,
DNSSEC_TSIG_HMAC_SHA1,
DNSSEC_TSIG_HMAC_SHA224,
DNSSEC_TSIG_HMAC_SHA256,
DNSSEC_TSIG_HMAC_SHA384,
DNSSEC_TSIG_HMAC_SHA512
} dnssec_tsig_algorithm_t;
/*!
* Get TSIG algorithm number from domain name.
*
* \see https://www.iana.org/assignments/tsig-algorithm-names/tsig-algorithm-names.xhtml
*
* \param dname Domain name of the algorithm (e.g., 0x0b hmac-sha256).
*
* \return TSIG algorithm.
*/
dnssec_tsig_algorithm_t dnssec_tsig_algorithm_from_dname(const uint8_t *dname);
/*!
* Get a domain name of the TSIG algorithm.
*
* \param algorithm TSIG algorithm.
*
* \return Domain name of the TSIG algorithm.
*/
const uint8_t *dnssec_tsig_algorithm_to_dname(dnssec_tsig_algorithm_t algorithm);
/*!
* Get TSIG algorithm from a MAC name.
*
* \param name MAC name (e.g., hmac-sha256).
*
* \return TSIG algorithm.
*/
dnssec_tsig_algorithm_t dnssec_tsig_algorithm_from_name(const char *name);
/*!
* Get MAC name from a TSIG algorithm.
*
* \param algorithm TSIG algorithm.
*
* \return MAC name of the TSIG algorithm.
*/
const char *dnssec_tsig_algorithm_to_name(dnssec_tsig_algorithm_t algorithm);
/*!
* Get optimal size of a TSIG algorithm.
*/
int dnssec_tsig_optimal_key_size(dnssec_tsig_algorithm_t algorithm);
struct dnssec_tsig_ctx;
/*!
* TSIG signing context.
*/
typedef struct dnssec_tsig_ctx dnssec_tsig_ctx_t;
/*!
* Create new TSIG signing context.
*
* \param[out] ctx Resulting TSIG context.
* \param[in] algorithm TSIG algorithm.
* \param[in] key Shared key to be used for signing.
*
* \return Error code, DNSSEC_EOK if successful.
*/
int dnssec_tsig_new(dnssec_tsig_ctx_t **ctx, dnssec_tsig_algorithm_t algorithm,
const dnssec_binary_t *key);
/*!
* Free the TSIG signing context.
*
* \param ctx TSIG signing context to be freed.
*/
void dnssec_tsig_free(dnssec_tsig_ctx_t *ctx);
/*!
* Add data to be signed by TSIG.
*
* \param ctx TSIG signing context.
* \param data Data to be signed.
*
* \return Error code, DNSSEC_EOK if successful.
*/
int dnssec_tsig_add(dnssec_tsig_ctx_t *ctx, const dnssec_binary_t *data);
/*!
* Get size of the TSIG signature for given signing context.
*
* \param ctx TSIG signing context.
*
* \return The size of the TSIG signature.
*/
size_t dnssec_tsig_size(dnssec_tsig_ctx_t *ctx);
/*!
* Get size of the TSIG signature for given algorithm.
*
* \param algorithm TSIG algorithm.
*
* \return The size of the TSIG signature.
*/
size_t dnssec_tsig_algorithm_size(dnssec_tsig_algorithm_t algorithm);
/*!
* Write TSIG signature.
*
* \param[in] ctx TSIG signing context.
* \param[out] mac Resulting TSIG signature.
*
* \return Error code, DNSSEC_EOK if successful.
*/
int dnssec_tsig_write(dnssec_tsig_ctx_t *ctx, uint8_t *mac);
/*! @} */
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