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/* Copyright (C) 2016-2017 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 <https://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include <nettle/hmac.h>
#include <stdint.h>
#include <stdlib.h>
#include <libknot/errcode.h>
#include <libknot/rrtype/opt-cookie.h>
#include "lib/cookies/alg_sha.h"
#include "lib/utils.h"
/**
* @brief Update hash value.
*
* @param ctx HMAC-SHA256 context to be updated.
* @param sa Socket address.
*/
static inline void update_hash(struct hmac_sha256_ctx *ctx,
const struct sockaddr *sa)
{
assert(ctx && sa);
int addr_len = kr_inaddr_len(sa);
const uint8_t *addr = (uint8_t *)kr_inaddr(sa);
if (addr && addr_len > 0) {
hmac_sha256_update(ctx, addr_len, addr);
}
}
/**
* @brief Compute client cookie using HMAC-SHA256-64.
* @note At least one of the arguments must be non-null.
* @param input input parameters
* @param cc_out buffer for computed client cookie
* @param cc_len buffer size
* @return Non-zero size of written data on success, 0 in case of a failure.
*/
static uint16_t cc_gen_hmac_sha256_64(const struct knot_cc_input *input,
uint8_t *cc_out, uint16_t cc_len)
{
if (!knot_cc_input_is_valid(input) ||
!cc_out || cc_len < KNOT_OPT_COOKIE_CLNT) {
return 0;
}
struct hmac_sha256_ctx ctx;
hmac_sha256_set_key(&ctx, input->secret_len, input->secret_data);
if (input->clnt_sockaddr) {
update_hash(&ctx, input->clnt_sockaddr);
}
if (input->srvr_sockaddr) {
update_hash(&ctx, input->srvr_sockaddr);
}
/* KNOT_OPT_COOKIE_CLNT <= SHA256_DIGEST_SIZE */
hmac_sha256_digest(&ctx, KNOT_OPT_COOKIE_CLNT, cc_out);
return KNOT_OPT_COOKIE_CLNT;
}
#define SRVR_HMAC_SHA256_64_HASH_SIZE 8
/**
* @brief Compute server cookie hash using HMAC-SHA256-64).
* @note Server cookie = nonce | time | HMAC-SHA256-64( server secret, client cookie | nonce| time | client IP )
* @param input data to compute cookie from
* @param hash_out hash output buffer
* @param hash_len buffer size
* @return Non-zero size of written data on success, 0 in case of a failure.
*/
static uint16_t sc_gen_hmac_sha256_64(const struct knot_sc_input *input,
uint8_t *hash_out, uint16_t hash_len)
{
if (!knot_sc_input_is_valid(input) ||
!hash_out || hash_len < SRVR_HMAC_SHA256_64_HASH_SIZE) {
return 0;
}
struct hmac_sha256_ctx ctx;
hmac_sha256_set_key(&ctx, input->srvr_data->secret_len,
input->srvr_data->secret_data);
hmac_sha256_update(&ctx, input->cc_len, input->cc);
if (input->nonce && input->nonce_len) {
hmac_sha256_update(&ctx, input->nonce_len, input->nonce);
}
if (input->srvr_data->clnt_sockaddr) {
update_hash(&ctx, input->srvr_data->clnt_sockaddr);
}
/* SRVR_HMAC_SHA256_64_HASH_SIZE < SHA256_DIGEST_SIZE */
hmac_sha256_digest(&ctx, SRVR_HMAC_SHA256_64_HASH_SIZE, hash_out);
return SRVR_HMAC_SHA256_64_HASH_SIZE;
}
const struct knot_cc_alg knot_cc_alg_hmac_sha256_64 = { KNOT_OPT_COOKIE_CLNT, cc_gen_hmac_sha256_64 };
const struct knot_sc_alg knot_sc_alg_hmac_sha256_64 = { SRVR_HMAC_SHA256_64_HASH_SIZE, sc_gen_hmac_sha256_64 };
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