Unify duplicate code in xsalsa20-poly1305 and aes128-gcm methods

1 files changed, 90 insertions, 0 deletions

diff --git a/src/methods/common.c b/src/methods/common.c
new file mode 100644
index 0000000..7c67253
--- /dev/null
+++ b/src/methods/common.c
@@ -0,0 +1,90 @@
+/*
+  Copyright (c) 2012-2013, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+
+#include "common.h"
+
+
+void fastd_method_common_init(fastd_context_t *ctx, fastd_method_common_t *session, bool initiator) {
+	memset(session, 0, sizeof(*session));
+
+	session->valid_till = ctx->now;
+	session->valid_till.tv_sec += ctx->conf->key_valid;
+
+	session->refresh_after = ctx->now;
+	session->refresh_after.tv_sec += ctx->conf->key_refresh - fastd_rand(ctx, 0, ctx->conf->key_refresh_splay);
+
+	if (initiator) {
+		session->send_nonce[0] = 3;
+	}
+	else {
+		session->send_nonce[0] = 2;
+		session->receive_nonce[0] = 1;
+	}
+}
+
+bool fastd_method_is_nonce_valid(fastd_context_t *ctx, const fastd_method_common_t *session, const uint8_t nonce[COMMON_NONCEBYTES], int64_t *age) {
+	if ((nonce[0] & 1) != (session->receive_nonce[0] & 1))
+		return false;
+
+	int i;
+	*age = 0;
+
+	for (i = COMMON_NONCEBYTES-1; i >= 0; i--) {
+		*age *= 256;
+		*age += session->receive_nonce[i]-nonce[i];
+	}
+
+	*age /= 2;
+
+	if (*age >= 0) {
+		if (timespec_diff(&ctx->now, &session->receive_last) > (int)ctx->conf->reorder_time*1000)
+			return false;
+
+		if (*age > ctx->conf->reorder_count)
+			return false;
+	}
+
+	return true;
+}
+
+bool fastd_method_reorder_check(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_common_t *session, const uint8_t nonce[COMMON_NONCEBYTES], int64_t age) {
+	if (age < 0) {
+		session->receive_reorder_seen >>= age;
+		session->receive_reorder_seen |= (1 >> (age+1));
+		memcpy(session->receive_nonce, nonce, COMMON_NONCEBYTES);
+		session->receive_last = ctx->now;
+		return true;
+	}
+	else if (age == 0 || session->receive_reorder_seen & (1 << (age-1))) {
+		pr_debug(ctx, "dropping duplicate packet from %P (age %u)", peer, (unsigned)age);
+		return false;
+	}
+	else {
+		pr_debug2(ctx, "accepting reordered packet from %P (age %u)", peer, (unsigned)age);
+		session->receive_reorder_seen |= (1 << (age-1));
+		return true;
+	}
+}