1 files changed, 114 insertions, 0 deletions
diff --git a/src/knot/modules/whoami/whoami.c b/src/knot/modules/whoami/whoami.c
new file mode 100644
index 0000000..99c4372
--- /dev/null
+++ b/src/knot/modules/whoami/whoami.c
@@ -0,0 +1,114 @@
+/*  Copyright (C) 2017 Fastly, Inc.
+
+    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 <netinet/in.h>
+
+#include "knot/include/module.h"
+
+static knotd_in_state_t whoami_query(knotd_in_state_t state, knot_pkt_t *pkt,
+                                     knotd_qdata_t *qdata, knotd_mod_t *mod)
+{
+	assert(pkt && qdata);
+
+	const knot_dname_t *zone_name = knotd_qdata_zone_name(qdata);
+	if (zone_name == NULL) {
+		return KNOTD_IN_STATE_ERROR;
+	}
+
+	/* Retrieve the query tuple. */
+	const knot_dname_t *qname = knot_pkt_qname(qdata->query);
+	const uint16_t qtype = knot_pkt_qtype(qdata->query);
+	const uint16_t qclass = knot_pkt_qclass(qdata->query);
+
+	/* We only generate A and AAAA records, which are Internet class. */
+	if (qclass != KNOT_CLASS_IN) {
+		return state;
+	}
+
+	/* Only handle queries with qname set to the zone name. */
+	if (!knot_dname_is_equal(qname, zone_name)) {
+		return state;
+	}
+
+	/* Only handle A and AAAA queries. */
+	if (qtype != KNOT_RRTYPE_A && qtype != KNOT_RRTYPE_AAAA) {
+		return state;
+	}
+
+	/* Retrieve the IP address that sent the query. */
+	const struct sockaddr_storage *query_source = knotd_qdata_remote_addr(qdata);
+	if (query_source == NULL) {
+		return KNOTD_IN_STATE_ERROR;
+	}
+
+	/* If the socket address family corresponds to the query type (i.e.,
+	 * AF_INET <-> A and AF_INET6 <-> AAAA), put the socket address and
+	 * length into 'rdata' and 'len_rdata'.
+	 */
+	const void *rdata = NULL;
+	uint16_t len_rdata = 0;
+	if (query_source->ss_family == AF_INET && qtype == KNOT_RRTYPE_A) {
+		const struct sockaddr_in *sai = (struct sockaddr_in *)query_source;
+		rdata = &sai->sin_addr.s_addr;
+		len_rdata = sizeof(sai->sin_addr.s_addr);
+	} else if (query_source->ss_family == AF_INET6 && qtype == KNOT_RRTYPE_AAAA) {
+		const struct sockaddr_in6 *sai6 = (struct sockaddr_in6 *)query_source;
+		rdata = &sai6->sin6_addr;
+		len_rdata = sizeof(sai6->sin6_addr);
+	} else {
+		/* Query type didn't match address family. */
+		return state;
+	}
+
+	/* Synthesize the response RRset. */
+
+	/* TTL is taken from the TTL of the SOA record. */
+	knot_rrset_t soa = knotd_qdata_zone_apex_rrset(qdata, KNOT_RRTYPE_SOA);
+
+	/* Owner name, type, and class are taken from the question. */
+	knot_rrset_t *rrset = knot_rrset_new(qname, qtype, qclass, soa.ttl, &pkt->mm);
+	if (rrset == NULL) {
+		return KNOTD_IN_STATE_ERROR;
+	}
+
+	/* Record data is the query source address. */
+	int ret = knot_rrset_add_rdata(rrset, rdata, len_rdata, &pkt->mm);
+	if (ret != KNOT_EOK) {
+		knot_rrset_free(rrset, &pkt->mm);
+		return KNOTD_IN_STATE_ERROR;
+	}
+
+	/* Add the new RRset to the response packet. */
+	ret = knot_pkt_put(pkt, KNOT_COMPR_HINT_QNAME, rrset, KNOT_PF_FREE);
+	if (ret != KNOT_EOK) {
+		knot_rrset_free(rrset, &pkt->mm);
+		return KNOTD_IN_STATE_ERROR;
+	}
+
+	/* Success. */
+	return KNOTD_IN_STATE_HIT;
+}
+
+int whoami_load(knotd_mod_t *mod)
+{
+	/* Hook to the query plan. */
+	knotd_mod_in_hook(mod, KNOTD_STAGE_ANSWER, whoami_query);
+
+	return KNOT_EOK;
+}
+
+KNOTD_MOD_API(whoami, KNOTD_MOD_FLAG_SCOPE_ZONE | KNOTD_MOD_FLAG_OPT_CONF,
+              whoami_load, NULL, NULL, NULL);