gopenfusion/cnet/peer.go

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package cnet
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import (
"bytes"
"context"
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"encoding/binary"
"fmt"
"io"
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"net"
"sync/atomic"
"github.com/CPunch/gopenfusion/cnet/protocol"
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)
const (
USE_E = iota
USE_FE
)
type PacketEvent struct {
Type int
Pkt *bytes.Buffer
PktID uint32
}
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// Peer is a simple wrapper for net.Conn connections to send/recv packets over the Fusionfall packet protocol.
type Peer struct {
uData interface{}
conn net.Conn
ctx context.Context
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 NewPeer(ctx context.Context, conn net.Conn) *Peer {
p := &Peer{
conn: conn,
ctx: ctx,
whichKey: USE_E,
alive: &atomic.Bool{},
E_key: []byte(protocol.DEFAULT_KEY),
FE_key: nil,
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}
return p
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}
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func (peer *Peer) SetUserData(uData interface{}) {
peer.uData = uData
}
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func (peer *Peer) UserData() interface{} {
return peer.uData
}
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func (peer *Peer) Send(typeID uint32, data ...interface{}) error {
// grab buffer from pool
buf := protocol.GetBuffer()
defer protocol.PutBuffer(buf)
// allocate space for packet size
buf.Write(make([]byte, 4))
// body start
pkt := protocol.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
}
protocol.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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}
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func (peer *Peer) SetActiveKey(whichKey int) {
peer.whichKey = whichKey
}
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func (peer *Peer) Kill() {
// de-bounce: only kill if alive
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if !peer.alive.CompareAndSwap(true, false) {
return
}
peer.conn.Close()
}
// meant to be invoked as a goroutine
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func (peer *Peer) Handler(eRecv chan<- *PacketEvent) error {
defer func() {
close(eRecv)
peer.Kill()
}()
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peer.alive.Store(true)
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for {
select {
case <-peer.ctx.Done():
return nil
default:
// 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
}
// client should never send a packet size outside of this range
if sz > protocol.CN_PACKET_BUFFER_SIZE || sz < 4 {
return fmt.Errorf("invalid packet size: %d", sz)
}
// grab buffer && read packet body
buf := protocol.GetBuffer()
if _, err := buf.ReadFrom(io.LimitReader(peer.conn, int64(sz))); err != nil {
return fmt.Errorf("failed to read packet body: %v", err)
}
// decrypt
protocol.DecryptData(buf.Bytes(), peer.E_key)
pkt := protocol.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 <- &PacketEvent{Pkt: buf, PktID: pktID}
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}
}
}