dragonfireclient/doc/protocol.md

Minetest protocol (incomplete, early draft): Updated 2011-06-18

A custom protocol over UDP. Integers are big endian. Refer to connection.{h,cpp} for further reference.

Initialization:

• A dummy reliable packet with peer_id=PEER_ID_INEXISTENT=0 is sent to the server:

  • Actually this can be sent without the reliable packet header, too, i guess, but the sequence number in the header allows the sender to re-send the packet without accidentally getting a double initialization.
  • Packet content:

    Basic header

    u32 protocol_id = PROTOCOL_ID = 0x4f457403 u16 sender_peer_id = PEER_ID_INEXISTENT = 0 u8 channel = 0

    Reliable packet header

    u8 type = TYPE_RELIABLE = 3 u16 seqnum = SEQNUM_INITIAL = 65500

    Original packet header

    u8 type = TYPE_ORIGINAL = 1

    And no actual payload.

• Server responds with something like this:

  • Packet content:

    Basic header

    u32 protocol_id = PROTOCOL_ID = 0x4f457403 u16 sender_peer_id = PEER_ID_INEXISTENT = 0 u8 channel = 0

    Reliable packet header

    u8 type = TYPE_RELIABLE = 3 u16 seqnum = SEQNUM_INITIAL = 65500

    Control packet header

    u8 type = TYPE_CONTROL = 0 u8 controltype = CONTROLTYPE_SET_PEER_ID = 1 u16 peer_id_new = assigned peer id to client (other than 0 or 1)

• Then the connection can be disconnected by sending:

  • Packet content:

    Basic header

    u32 protocol_id = PROTOCOL_ID = 0x4f457403 u16 sender_peer_id = whatever was gotten in CONTROLTYPE_SET_PEER_ID u8 channel = 0

    Control packet header

    u8 type = TYPE_CONTROL = 0 u8 controltype = CONTROLTYPE_DISCO = 3

• Here's a quick untested connect-disconnect done in PHP:

host: ip of server (use gethostbyname(hostname) to get from a dns name)

port: port of server

function check_if_minetestserver_up($host, $port) { $socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); $timeout = array("sec" => 1, "usec" => 0); socket_set_option($socket, SOL_SOCKET, SO_RCVTIMEO, $timeout); $buf = "\x4f\x45\x74\x03\x00\x00\x00\x03\xff\xdc\x01"; socket_sendto($socket, $buf, strlen($buf), 0, $host, $port); $buf = socket_read($socket, 1000); if($buf != "") { # We got a reply! read the peer id from it. $peer_id = substr($buf, 9, 2);

	# Disconnect
	$buf = "\x4f\x45\x74\x03".$peer_id."\x00\x00\x03";
	socket_sendto($socket, $buf, strlen($buf), 0, $host, $port);
	socket_close($socket);

	return true;
}
return false;

}

• Here's a Python script for checking if a minetest server is up, confirmed working

#!/usr/bin/env python3 import sys, time, socket

address = "" port = 30000 if len(sys.argv) <= 1: print("Usage: %s

" % sys.argv[0]) exit() if ":" in sys.argv[1]: address = sys.argv[1].split(":")[0] try: port = int(sys.argv[1].split(":")[1]) except ValueError: print("Please specify a valid port") exit() else: address = sys.argv[1]

try: start = time.time() sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.settimeout(2.0) buf = b"\x4f\x45\x74\x03\x00\x00\x00\x01" sock.sendto(buf, (address, port)) data, addr = sock.recvfrom(1000) if data: peer_id = data[12:14] buf = b"\x4f\x45\x74\x03" + peer_id + b"\x00\x00\x03" sock.sendto(buf, (address, port)) sock.close() end = time.time() print("%s is up (%0.5fms)" % (sys.argv[1], end - start)) else: print("%s seems to be down " % sys.argv[1]) except Exception as err: print("%s seems to be down (%s) " % (sys.argv[1], str(err)))