gopenfusion/internal/protocol/cnpeer.go

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package protocol
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import (
"encoding/binary"
"fmt"
"io"
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"log"
"net"
"sync/atomic"
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"time"
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)
const (
USE_E = iota
USE_FE
)
// CNPeer is a simple wrapper for net.Conn connections to send/recv packets over the Fusionfall packet protocol.
type CNPeer struct {
conn net.Conn
whichKey int
alive *atomic.Bool
// May not be set while Send() or Handler() are concurrently running.
E_key []byte
// May not be set while Send() or Handler() are concurrently running.
FE_key []byte
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}
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func GetTime() uint64 {
return uint64(time.Now().UnixMilli())
}
func NewCNPeer(conn net.Conn) *CNPeer {
p := &CNPeer{
conn: conn,
whichKey: USE_E,
alive: &atomic.Bool{},
E_key: []byte(DEFAULT_KEY),
FE_key: nil,
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}
return p
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}
func (peer *CNPeer) Send(typeID uint32, data ...interface{}) error {
// grab buffer from pool
buf := GetBuffer()
defer PutBuffer(buf)
// allocate space for packet size
buf.Write(make([]byte, 4))
// body start
pkt := NewPacket(buf)
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// encode type id
if err := pkt.Encode(typeID); err != nil {
return err
}
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// encode data
for _, trailer := range data {
if err := pkt.Encode(trailer); err != nil {
return err
}
}
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// prepend the packet size
binary.LittleEndian.PutUint32(buf.Bytes()[:4], uint32(buf.Len()-4))
// encrypt body
var key []byte
switch peer.whichKey {
case USE_E:
key = peer.E_key
case USE_FE:
key = peer.FE_key
}
EncryptData(buf.Bytes()[4:], key)
// send full packet
log.Printf("Sending %#v, sizeof: %d, buffer: %v", data, buf.Len(), buf.Bytes())
if _, err := peer.conn.Write(buf.Bytes()); err != nil {
return fmt.Errorf("failed to write packet body! %v", err)
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}
return nil
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}
func (peer *CNPeer) SetActiveKey(whichKey int) {
peer.whichKey = whichKey
}
func (peer *CNPeer) Kill() {
// de-bounce: only kill if alive
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if !peer.alive.CompareAndSwap(true, false) {
return
}
log.Printf("Killing peer %p", peer)
peer.conn.Close()
}
// meant to be invoked as a goroutine
func (peer *CNPeer) Handler(eRecv chan<- *Event) error {
defer func() {
eRecv <- &Event{Type: EVENT_CLIENT_DISCONNECT, Peer: peer}
close(eRecv)
peer.Kill()
}()
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peer.alive.Store(true)
eRecv <- &Event{Type: EVENT_CLIENT_CONNECT, Peer: peer}
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for {
// read packet size, the goroutine spends most of it's time parked here
var sz uint32
if err := binary.Read(peer.conn, binary.LittleEndian, &sz); err != nil {
return err
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}
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// client should never send a packet size outside of this range
if sz > CN_PACKET_BUFFER_SIZE || sz < 4 {
return fmt.Errorf("invalid packet size: %d", sz)
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}
// grab buffer && read packet body
buf := GetBuffer()
if _, err := buf.ReadFrom(io.LimitReader(peer.conn, int64(sz))); err != nil {
return fmt.Errorf("failed to read packet body: %v", err)
}
// decrypt
DecryptData(buf.Bytes(), peer.E_key)
pkt := NewPacket(buf)
// create packet && read pktID
var pktID uint32
if err := pkt.Decode(&pktID); err != nil {
return fmt.Errorf("failed to read packet type! %v", err)
}
// dispatch packet
// log.Printf("Got packet ID: %x, with a sizeof: %d\n", pktID, sz)
eRecv <- &Event{Type: EVENT_CLIENT_PACKET, Peer: peer, Pkt: buf, PktID: pktID}
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}
}