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-rw-r--r--modules/nsid/nsid.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/modules/nsid/nsid.c b/modules/nsid/nsid.c
new file mode 100644
index 0000000..c0eabfd
--- /dev/null
+++ b/modules/nsid/nsid.c
@@ -0,0 +1,114 @@
+/* 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_verbose("[%05u. ][nsid] 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 (req->answer->opt_rr == NULL)
+ 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_verbose("[%05u. ][nsid] 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)