Bounds checking for socks domain name inputs.

lib/socks_mosq.c

@@ -336,8 +336,10 @@ int mosquitto__socks5_read(struct mosquitto *mosq)
 				mosq->in_packet.to_process += 16+2-1; /* 16 bytes IPv6, 2 bytes port, -1 byte because we've already read the first byte */
 				mosq->in_packet.packet_length += 16+2-1;
 			}else if(mosq->in_packet.payload[3] == SOCKS_ATYPE_DOMAINNAME){
-				mosq->in_packet.to_process += mosq->in_packet.payload[4];
-				mosq->in_packet.packet_length += mosq->in_packet.payload[4];
+				if(mosq->in_packet.payload[4] > 0 && mosq->in_packet.payload[4] <= 255){
+					mosq->in_packet.to_process += mosq->in_packet.payload[4];
+					mosq->in_packet.packet_length += mosq->in_packet.payload[4];
+				}
 			}else{
 				_mosquitto_packet_cleanup(&mosq->in_packet);
 				return MOSQ_ERR_PROTOCOL;