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