Add minimum handshake interval for unknown addresses (handles up to 8 addresses for now)

1 files changed, 32 insertions, 1 deletions

diff --git a/src/receive.c b/src/receive.c
index 472b664..fa45dde 100644
--- a/src/receive.c
+++ b/src/receive.c
@@ -105,6 +105,35 @@ static inline bool allow_unknown_peers(fastd_context_t *ctx) {
 	return ctx->conf->has_floating || ctx->conf->on_verify;
 }
 
+static inline bool backoff_unknown(fastd_context_t *ctx, const fastd_peer_address_t *addr) {
+	size_t i;
+	for (i = 0; i < array_size(ctx->unknown_handshakes); i++) {
+		const fastd_handshake_timeout_t *t = &ctx->unknown_handshakes[(ctx->unknown_handshake_pos + i) % array_size(ctx->unknown_handshakes)];
+
+		if (!timespec_after(&t->timeout, &ctx->now))
+			break;
+
+		if (fastd_peer_address_equal(addr, &t->address)) {
+			pr_debug2(ctx, "sent a handshake to unknown address %I a short time ago, not sending again", addr);
+			return true;
+		}
+	}
+
+	if (ctx->unknown_handshake_pos == 0)
+		ctx->unknown_handshake_pos = array_size(ctx->unknown_handshakes)-1;
+	else
+		ctx->unknown_handshake_pos--;
+
+	fastd_handshake_timeout_t *t = &ctx->unknown_handshakes[ctx->unknown_handshake_pos];
+
+	t->address = *addr;
+
+	t->timeout = ctx->now;
+	t->timeout.tv_sec += ctx->conf->min_handshake_interval;
+
+	return false;
+}
+
 static inline void handle_socket_receive_unknown(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_buffer_t buffer) {
 	const uint8_t *packet_type = buffer.data;
 	fastd_buffer_push_head(ctx, &buffer, 1);
@@ -112,7 +141,9 @@ static inline void handle_socket_receive_unknown(fastd_context_t *ctx, fastd_soc
 	switch (*packet_type) {
 	case PACKET_DATA:
 		fastd_buffer_free(buffer);
-		ctx->conf->protocol->handshake_init(ctx, sock, local_addr, remote_addr, NULL);
+
+		if (!backoff_unknown(ctx, remote_addr))
+			ctx->conf->protocol->handshake_init(ctx, sock, local_addr, remote_addr, NULL);
 		break;
 
 	case PACKET_HANDSHAKE: