Configurable ReplayWindow size, zero disables

src/net.h

@@ -106,6 +106,7 @@ extern list_t *outgoing_list;
 extern int maxoutbufsize;
 extern int seconds_till_retry;
 extern int addressfamily;
+extern unsigned replaywin;
 
 extern listen_socket_t listen_socket[MAXSOCKETS];
 extern int listen_sockets;

src/net_packet.c

@@ -60,6 +60,8 @@ static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999
 
 static void send_udppacket(node_t *, vpn_packet_t *);
 
+unsigned replaywin = 16;
+
 #define MAX_SEQNO 1073741824
 
 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
@@ -293,25 +295,27 @@ static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 	inpkt->len -= sizeof(inpkt->seqno);
 	inpkt->seqno = ntohl(inpkt->seqno);
 
-	if(inpkt->seqno != n->received_seqno + 1) {
-		if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
-			logger(LOG_WARNING, "Lost %d packets from %s (%s)",
-					   inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
-			
-			memset(n->late, 0, sizeof(n->late));
-		} else if (inpkt->seqno <= n->received_seqno) {
-			if((n->received_seqno >= sizeof(n->late) * 8 && inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8) || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
-				logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
-					   n->name, n->hostname, inpkt->seqno, n->received_seqno);
-				return;
+	if(replaywin) {
+		if(inpkt->seqno != n->received_seqno + 1) {
+			if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
+				logger(LOG_WARNING, "Lost %d packets from %s (%s)",
+					   	inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
+				
+				memset(n->late, 0, replaywin);
+			} else if (inpkt->seqno <= n->received_seqno) {
+				if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) {
+					logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
+					   	n->name, n->hostname, inpkt->seqno, n->received_seqno);
+					return;
+				}
+			} else {
+				for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
+					n->late[(i / 8) % replaywin] |= 1 << i % 8;
 			}
-		} else {
-			for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
-				n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
 		}
-	}
 	
-	n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
+		n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
+	}
 
 	if(inpkt->seqno > n->received_seqno)
 		n->received_seqno = inpkt->seqno;

src/net_setup.c

@@ -276,6 +276,7 @@ bool setup_myself(void) {
 	struct addrinfo *ai, *aip, hint = {0};
 	bool choice;
 	int i, err;
+	int replaywin_int;
 
 	myself = new_node();
 	myself->connection = new_connection();
@@ -419,6 +420,14 @@ bool setup_myself(void) {
 		}
 	}
 
+	if(get_config_int(lookup_config(config_tree, "ReplayWindow"), &replaywin_int)) {
+		if(replaywin_int < 0) {
+			logger(LOG_ERR, "ReplayWindow cannot be negative!");
+			return false;
+		}
+		replaywin = (unsigned)replaywin_int;
+	}
+
 	if(get_config_string(lookup_config(config_tree, "AddressFamily"), &afname)) {
 		if(!strcasecmp(afname, "IPv4"))
 			addressfamily = AF_INET;

src/node.c

@@ -54,6 +54,7 @@ void exit_nodes(void) {
 node_t *new_node(void) {
 	node_t *n = xmalloc_and_zero(sizeof(*n));
 
+	if(replaywin) n->late = xmalloc_and_zero(replaywin);
 	n->subnet_tree = new_subnet_tree();
 	n->edge_tree = new_edge_tree();
 	EVP_CIPHER_CTX_init(&n->inctx);

src/node.h

@@ -77,7 +77,7 @@ typedef struct node_t {
 
 	uint32_t sent_seqno;			/* Sequence number last sent to this node */
 	uint32_t received_seqno;		/* Sequence number last received from this node */
-	unsigned char late[16];			/* Bitfield marking late packets */
+	unsigned char* late;			/* Bitfield marking late packets */
 
 	length_t mtu;				/* Maximum size of packets to send to this node */
 	length_t minmtu;			/* Probed minimum MTU */

src/protocol_key.c

@@ -163,7 +163,7 @@ bool send_ans_key(node_t *to) {
 	// Reset sequence number and late packet window
 	mykeyused = true;
 	to->received_seqno = 0;
-	memset(to->late, 0, sizeof(to->late));
+	if(replaywin) memset(to->late, 0, replaywin);
 
 	// Convert to hexadecimal and send
 	char key[2 * to->inkeylength + 1];