1 files changed, 130 insertions, 0 deletions
diff --git a/src/libknot/cookies.c b/src/libknot/cookies.c
new file mode 100644
index 0000000..dd024d5
--- /dev/null
+++ b/src/libknot/cookies.c
@@ -0,0 +1,130 @@
+/*  Copyright (C) 2017 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 <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <stdbool.h>
+
+#include "libknot/attribute.h"
+#include "libknot/cookies.h"
+#include "libknot/errcode.h"
+#include "contrib/string.h"
+#include "contrib/sockaddr.h"
+#include "contrib/openbsd/siphash.h"
+
+_public_
+int knot_edns_cookie_client_generate(knot_edns_cookie_t *out,
+                                     const knot_edns_cookie_params_t *params)
+{
+	if (out == NULL || params == NULL || params->client_addr == NULL ||
+	    params->server_addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	SIPHASH_CTX ctx;
+	assert(sizeof(params->secret) == sizeof(SIPHASH_KEY));
+	SipHash24_Init(&ctx, (const SIPHASH_KEY *)params->secret);
+
+	size_t addr_len = 0;
+	void *addr = sockaddr_raw(params->client_addr, &addr_len);
+	SipHash24_Update(&ctx, addr, addr_len);
+
+	addr_len = 0;
+	addr = sockaddr_raw(params->server_addr, &addr_len);
+	SipHash24_Update(&ctx, addr, addr_len);
+
+	uint64_t hash = SipHash24_End(&ctx);
+	memcpy(out->data, &hash, sizeof(hash));
+	out->len = sizeof(hash);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_cookie_client_check(const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params)
+{
+	if (cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE) {
+		return KNOT_EINVAL;
+	}
+
+	knot_edns_cookie_t ref;
+	int ret = knot_edns_cookie_client_generate(&ref, params);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	assert(ref.len == KNOT_EDNS_COOKIE_CLNT_SIZE);
+
+	ret = const_time_memcmp(cc->data, ref.data, KNOT_EDNS_COOKIE_CLNT_SIZE);
+	if (ret != 0) {
+		return KNOT_EINVAL;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_cookie_server_generate(knot_edns_cookie_t *out,
+                                     const knot_edns_cookie_t *cc,
+                                     const knot_edns_cookie_params_t *params)
+{
+	if (out == NULL || cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE ||
+	    params == NULL || params->client_addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	SIPHASH_CTX ctx;
+	assert(sizeof(params->secret) == sizeof(SIPHASH_KEY));
+	SipHash24_Init(&ctx, (const SIPHASH_KEY *)params->secret);
+
+	size_t addr_len = 0;
+	void *addr = sockaddr_raw(params->client_addr, &addr_len);
+	SipHash24_Update(&ctx, addr, addr_len);
+
+	SipHash24_Update(&ctx, cc->data, cc->len);
+
+	uint64_t hash = SipHash24_End(&ctx);
+	memcpy(out->data, &hash, sizeof(hash));
+	out->len = sizeof(hash);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_cookie_server_check(const knot_edns_cookie_t *sc,
+                                  const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params)
+{
+	if (sc == NULL || cc == NULL || params == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_edns_cookie_t ref;
+	int ret = knot_edns_cookie_server_generate(&ref, cc, params);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	if (sc->len != ref.len) {
+		return KNOT_EINVAL;
+	}
+
+	ret = const_time_memcmp(sc->data, ref.data, sc->len);
+	if (ret != 0) {
+		return KNOT_EINVAL;
+	}
+
+	return KNOT_EOK;
+}