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/* Copyright (C) 2019 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 "knot/nameserver/tsig_ctx.h"
#include "contrib/string.h"
#include "libknot/libknot.h"
/*!
* Maximal total size for unsigned messages.
*/
static const size_t TSIG_BUFFER_MAX_SIZE = (UINT16_MAX * 100);
void tsig_init(tsig_ctx_t *ctx, const knot_tsig_key_t *key)
{
if (!ctx) {
return;
}
memzero(ctx, sizeof(*ctx));
ctx->key = key;
}
void tsig_cleanup(tsig_ctx_t *ctx)
{
if (!ctx) {
return;
}
free(ctx->buffer);
memzero(ctx, sizeof(*ctx));
}
void tsig_reset(tsig_ctx_t *ctx)
{
if (!ctx) {
return;
}
const knot_tsig_key_t *backup = ctx->key;
tsig_cleanup(ctx);
tsig_init(ctx, backup);
}
int tsig_sign_packet(tsig_ctx_t *ctx, knot_pkt_t *packet)
{
if (!ctx || !packet) {
return KNOT_EINVAL;
}
if (ctx->key == NULL) {
return KNOT_EOK;
}
int ret = KNOT_ERROR;
if (ctx->digest_size == 0) {
ctx->digest_size = dnssec_tsig_algorithm_size(ctx->key->algorithm);
ret = knot_tsig_sign(packet->wire, &packet->size, packet->max_size,
NULL, 0,
ctx->digest, &ctx->digest_size,
ctx->key, 0, 0);
} else {
uint8_t previous_digest[ctx->digest_size];
memcpy(previous_digest, ctx->digest, ctx->digest_size);
ret = knot_tsig_sign_next(packet->wire, &packet->size, packet->max_size,
previous_digest, ctx->digest_size,
ctx->digest, &ctx->digest_size,
ctx->key, packet->wire, packet->size);
}
return ret;
}
static int update_ctx_after_verify(tsig_ctx_t *ctx, knot_rrset_t *tsig_rr)
{
assert(ctx);
assert(tsig_rr);
if (ctx->digest_size != knot_tsig_rdata_mac_length(tsig_rr)) {
return KNOT_EMALF;
}
memcpy(ctx->digest, knot_tsig_rdata_mac(tsig_rr), ctx->digest_size);
ctx->prev_signed_time = knot_tsig_rdata_time_signed(tsig_rr);
ctx->unsigned_count = 0;
ctx->buffer_used = 0;
return KNOT_EOK;
}
static int buffer_add_packet(tsig_ctx_t *ctx, knot_pkt_t *packet)
{
size_t need = ctx->buffer_used + packet->size;
// Inflate the buffer if necessary.
if (need > TSIG_BUFFER_MAX_SIZE) {
return KNOT_ENOMEM;
}
if (need > ctx->buffer_size) {
uint8_t *buffer = realloc(ctx->buffer, need);
if (!buffer) {
return KNOT_ENOMEM;
}
ctx->buffer = buffer;
ctx->buffer_size = need;
}
// Buffer the packet.
uint8_t *write = ctx->buffer + ctx->buffer_used;
memcpy(write, packet->wire, packet->size);
ctx->buffer_used = need;
return KNOT_EOK;
}
int tsig_verify_packet(tsig_ctx_t *ctx, knot_pkt_t *packet)
{
if (!ctx || !packet) {
return KNOT_EINVAL;
}
if (ctx->key == NULL) {
return KNOT_EOK;
}
int ret = buffer_add_packet(ctx, packet);
if (ret != KNOT_EOK) {
return ret;
}
// Unsigned packet.
if (packet->tsig_rr == NULL) {
ctx->unsigned_count += 1;
return KNOT_EOK;
}
// Signed packet.
if (ctx->prev_signed_time == 0) {
ret = knot_tsig_client_check(packet->tsig_rr, ctx->buffer,
ctx->buffer_used, ctx->digest,
ctx->digest_size, ctx->key, 0);
} else {
ret = knot_tsig_client_check_next(packet->tsig_rr, ctx->buffer,
ctx->buffer_used, ctx->digest,
ctx->digest_size, ctx->key,
ctx->prev_signed_time);
}
if (ret != KNOT_EOK) {
return ret;
}
ret = update_ctx_after_verify(ctx, packet->tsig_rr);
if (ret != KNOT_EOK) {
return ret;
}
return KNOT_EOK;
}
unsigned tsig_unsigned_count(tsig_ctx_t *ctx)
{
if (!ctx) {
return -1;
}
return ctx->unsigned_count;
}
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