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/*
Package rudp implements the low-level Minetest protocol described at
https://dev.minetest.net/Network_Protocol#Low-level_protocol.
*/
package rudp
import (
"encoding/binary"
"errors"
"io"
"time"
)
var be = binary.BigEndian
/*
UDP packet format:
protoID
src PeerID
channel uint8
rawType...
*/
var ErrTimedOut = errors.New("timed out")
const (
ConnTimeout = 30 * time.Second
PingTimeout = 5 * time.Second
)
const (
MaxRelPktSize = 32439825
MaxUnrelPktSize = 32636430
)
// protoID must be at the start of every UDP packet.
const protoID uint32 = 0x4f457403
// PeerIDs aren't actually used to identify peers, IP addresses and ports are,
// these just exist for backward compatibility.
type PeerID uint16
const (
// Used by clients before the server sets their ID.
PeerIDNil PeerID = iota
// The server always has this ID.
PeerIDSrv
// Lowest ID the server can assign to a client.
PeerIDCltMin
)
type rawType uint8
const (
rawCtl rawType = iota
// ctlType...
rawOrig
// data...
rawSplit
// seqnum
// n, i uint16
// data...
rawRel
// seqnum
// rawType...
)
type ctlType uint8
const (
ctlAck ctlType = iota
// seqnum
ctlSetPeerID
// PeerID
ctlPing // Sent to prevent timeout.
ctlDisco
)
type Pkt struct {
io.Reader
PktInfo
}
// Reliable packets in a channel are be received in the order they are sent in.
// A Channel must be less than ChannelCount.
type Channel uint8
const ChannelCount Channel = 3
type PktInfo struct {
Channel
// Unrel (unreliable) packets may be dropped, duplicated or reordered.
Unrel bool
}
// seqnums are sequence numbers used to maintain reliable packet order
// and identify split packets.
type seqnum uint16
const initSeqnum seqnum = 65500
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