X-Git-Url: https://tinc-vpn.org/git/browse?a=blobdiff_plain;ds=sidebyside;f=src%2Fnet_packet.c;h=0021aabb691bf26bed1d1a6e5ee1f2788c86057d;hb=545ecb339654573b3ee91bffb45c8282154885c6;hp=37535c17c0cc355821fb6786d89f4bbcfe75cccf;hpb=0e653260478005eb7c824a9a1a3df04f39938cd6;p=tinc

diff --git a/src/net_packet.c b/src/net_packet.c
index 37535c17..0021aabb 100644
--- a/src/net_packet.c
+++ b/src/net_packet.c
@@ -97,10 +97,16 @@ static void udp_probe_timeout_handler(void *data) {
 
 static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 	if(!DATA(packet)[0]) {
-		logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request %d from %s (%s)", packet->len, n->name, n->hostname);
-
 		/* It's a probe request, send back a reply */
 
+		if(!n->status.sptps && !n->status.validkey) {
+			// But not if we don't have his key.
+			logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request from %s (%s) but we don't have his key yet", n->name, n->hostname);
+			return;
+		}
+
+		logger(DEBUG_TRAFFIC, LOG_INFO, "Got UDP probe request %d from %s (%s)", packet->len, n->name, n->hostname);
+
 		/* Type 2 probe replies were introduced in protocol 17.3 */
 		if ((n->options >> 24) >= 3) {
 			uint8_t *data = DATA(packet);
@@ -110,7 +116,7 @@ static void udp_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 			gettimeofday(&now, NULL);
 			uint32_t sec = htonl(now.tv_sec); memcpy(data, &sec, 4); data += 4;
 			uint32_t usec = htonl(now.tv_usec); memcpy(data, &usec, 4); data += 4;
-			packet->len -= 10;
+			packet->len = 14; // Minimum size for any probe packet.
 		} else {
 			/* Legacy protocol: n won't understand type 2 probe replies. */
 			DATA(packet)[0] = 1;
@@ -929,6 +935,25 @@ static length_t choose_initial_maxmtu(node_t *n) {
 		mtu -= SPTPS_DATAGRAM_OVERHEAD;
 		if((n->options >> 24) >= 4)
 			mtu -= sizeof(node_id_t) + sizeof(node_id_t);
+	} else {
+		mtu -= digest_length(n->outdigest);
+
+		/* Now it's tricky. We use CBC mode, so the length of the
+		   encrypted payload must be a multiple of the blocksize. The
+		   sequence number is also part of the encrypted payload, so we
+		   must account for it after correcting for the blocksize.
+		   Furthermore, the padding in the last block must be at least
+		   1 byte. */
+
+		length_t blocksize = cipher_blocksize(n->outcipher);
+
+		if(blocksize > 1) {
+			mtu /= blocksize;
+			mtu *= blocksize;
+			mtu--;
+		}
+
+		mtu -= 4; // seqno
 	}
 
 	if (mtu < 512) {
@@ -1092,6 +1117,11 @@ static void try_tx_sptps(node_t *n) {
 }
 
 static void try_tx_legacy(node_t *n) {
+	/* Does he have our key? If not, send one. */
+
+	if(!n->status.validkey_in)
+		send_ans_key(n);
+
 	/* Check if we already have a key, or request one. */
 
 	if(!n->status.validkey) {