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/* Copyright (C) Knot Resolver contributors
* SPDX-License-Identifier: GPL-3.0-or-later
*
* This module provides NSID support according to RFC 5001. */
#include <libknot/packet/pkt.h>
#include <contrib/cleanup.h>
#include <ccan/json/json.h>
#include <lauxlib.h>
#include "daemon/engine.h"
#include "lib/layer.h"
struct nsid_config {
uint8_t *local_nsid;
size_t local_nsid_len;
};
static int nsid_finalize(kr_layer_t *ctx) {
const struct kr_module *module = ctx->api->data;
const struct nsid_config *config = module->data;
struct kr_request *req = ctx->req;
/* no local NSID configured, do nothing */
if (config->local_nsid == NULL)
return ctx->state;
const knot_rrset_t *src_opt = req->qsource.packet->opt_rr;
/* no EDNS in request, do nothing */
if (src_opt == NULL)
return ctx->state;
const uint8_t *req_nsid = knot_edns_get_option(src_opt, KNOT_EDNS_OPTION_NSID, NULL);
/* NSID option must be explicitly requested */
if (req_nsid == NULL)
return ctx->state;
/* Check violation of https://tools.ietf.org/html/rfc5001#section-2.1:
* The resolver MUST NOT include any NSID payload data in the query */
if (knot_edns_opt_get_length(req_nsid) != 0)
kr_log_debug(NSID, "[%05u. ] FORMERR: NSID option in query "
"must not contain payload, continuing\n", req->uid);
/* FIXME: actually change RCODE in answer to FORMERR? */
/* Sanity check, answer should have EDNS as well but who knows ... */
if (kr_fails_assert(req->answer->opt_rr))
return ctx->state;
if (knot_edns_add_option(req->answer->opt_rr, KNOT_EDNS_OPTION_NSID,
config->local_nsid_len, config->local_nsid,
&req->pool) != KNOT_EOK) {
/* something went wrong and there is no way to salvage content of OPT RRset */
kr_log_debug(NSID, "[%05u. ] unable to add NSID option\n", req->uid);
knot_rrset_clear(req->answer->opt_rr, &req->pool);
}
return ctx->state;
}
static char* nsid_name(void *env, struct kr_module *module, const char *args)
{
struct engine *engine = env;
struct nsid_config *config = module->data;
if (args) { /* set */
/* API is not binary safe, we need to fix this one day */
uint8_t *arg_copy = (uint8_t *)strdup(args);
if (arg_copy == NULL)
luaL_error(engine->L, "[nsid] error while allocating new NSID value\n");
free(config->local_nsid);
config->local_nsid = arg_copy;
config->local_nsid_len = strlen(args);
}
/* get */
if (config->local_nsid != NULL)
return json_encode_string((char *)config->local_nsid);
else
return NULL;
}
KR_EXPORT
int nsid_init(struct kr_module *module) {
static kr_layer_api_t layer = {
.answer_finalize = &nsid_finalize,
};
layer.data = module;
module->layer = &layer;
static const struct kr_prop props[] = {
{ &nsid_name, "name", "Get or set local NSID value" },
{ NULL, NULL, NULL }
};
module->props = props;
struct nsid_config *config = calloc(1, sizeof(struct nsid_config));
if (config == NULL)
return kr_error(ENOMEM);
module->data = config;
return kr_ok();
}
KR_EXPORT
int nsid_deinit(struct kr_module *module) {
struct nsid_config *config = module->data;
if (config != NULL) {
free(config->local_nsid);
free(config);
module->data = NULL;
}
return kr_ok();
}
KR_MODULE_EXPORT(nsid)
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