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/* Copyright (C) 2022 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 "knot/include/module.h"
#define MOD_UDP_ALLOW_RATE "\x0e""udp-allow-rate"
#define MOD_UDP_TRUNC_RATE "\x11""udp-truncate-rate"
const yp_item_t noudp_conf[] = {
{ MOD_UDP_ALLOW_RATE, YP_TINT, YP_VINT = { 0, UINT32_MAX, 0 } },
{ MOD_UDP_TRUNC_RATE, YP_TINT, YP_VINT = { 1, UINT32_MAX, 0 } },
{ NULL }
};
int noudp_conf_check(knotd_conf_check_args_t *args)
{
knotd_conf_t allow = knotd_conf_check_item(args, MOD_UDP_ALLOW_RATE);
knotd_conf_t trunc = knotd_conf_check_item(args, MOD_UDP_TRUNC_RATE);
if (allow.count == 1 && trunc.count == 1) {
args->err_str = "udp-allow-rate and udp-truncate-rate cannot be specified together";
return KNOT_EINVAL;
}
return KNOT_EOK;
}
typedef struct {
uint32_t rate;
uint32_t *counters;
bool trunc_mode;
} noudp_ctx_t;
static knotd_state_t noudp_begin(knotd_state_t state, knot_pkt_t *pkt,
knotd_qdata_t *qdata, knotd_mod_t *mod)
{
if (qdata->params->proto != KNOTD_QUERY_PROTO_UDP) {
return state;
}
bool truncate = true;
noudp_ctx_t *ctx = knotd_mod_ctx(mod);
if (ctx->rate > 0) {
bool apply = false;
if (++ctx->counters[qdata->params->thread_id] >= ctx->rate) {
ctx->counters[qdata->params->thread_id] = 0;
apply = true;
}
truncate = (apply == ctx->trunc_mode);
}
if (truncate) {
knot_wire_set_tc(pkt->wire);
return KNOTD_STATE_DONE;
} else {
return state;
}
}
int noudp_load(knotd_mod_t *mod)
{
noudp_ctx_t *ctx = calloc(1, sizeof(noudp_ctx_t));
if (ctx == NULL) {
return KNOT_ENOMEM;
}
knotd_conf_t allow = knotd_conf_mod(mod, MOD_UDP_ALLOW_RATE);
knotd_conf_t trunc = knotd_conf_mod(mod, MOD_UDP_TRUNC_RATE);
if (allow.count == 1) {
ctx->rate = allow.single.integer;
} else if (trunc.count == 1) {
ctx->rate = trunc.single.integer;
ctx->trunc_mode = true;
}
if (ctx->rate > 0) {
ctx->counters = calloc(knotd_mod_threads(mod), sizeof(uint32_t));
if (ctx->counters == NULL) {
free(ctx);
return KNOT_ENOMEM;
}
}
knotd_mod_ctx_set(mod, ctx);
return knotd_mod_hook(mod, KNOTD_STAGE_BEGIN, noudp_begin);
}
void noudp_unload(knotd_mod_t *mod)
{
noudp_ctx_t *ctx = knotd_mod_ctx(mod);
free(ctx->counters);
free(ctx);
}
KNOTD_MOD_API(noudp, KNOTD_MOD_FLAG_SCOPE_ANY | KNOTD_MOD_FLAG_OPT_CONF,
noudp_load, noudp_unload, noudp_conf, noudp_conf_check);
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