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package udp
import (
"context"
"io"
"sync"
"time"
"v2ray.com/core/common/signal/done"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/net"
"v2ray.com/core/common/protocol/udp"
"v2ray.com/core/common/session"
"v2ray.com/core/common/signal"
"v2ray.com/core/features/routing"
"v2ray.com/core/transport"
)
type ResponseCallback func(ctx context.Context, packet *udp.Packet)
type connEntry struct {
link *transport.Link
timer signal.ActivityUpdater
cancel context.CancelFunc
}
type Dispatcher struct {
sync.RWMutex
conns map[net.Destination]*connEntry
dispatcher routing.Dispatcher
callback ResponseCallback
}
func NewDispatcher(dispatcher routing.Dispatcher, callback ResponseCallback) *Dispatcher {
return &Dispatcher{
conns: make(map[net.Destination]*connEntry),
dispatcher: dispatcher,
callback: callback,
}
}
func (v *Dispatcher) RemoveRay(dest net.Destination) {
v.Lock()
defer v.Unlock()
if conn, found := v.conns[dest]; found {
common.Close(conn.link.Reader)
common.Close(conn.link.Writer)
delete(v.conns, dest)
}
}
func (v *Dispatcher) getInboundRay(ctx context.Context, dest net.Destination) *connEntry {
v.Lock()
defer v.Unlock()
if entry, found := v.conns[dest]; found {
return entry
}
newError("establishing new connection for ", dest).WriteToLog()
ctx, cancel := context.WithCancel(ctx)
removeRay := func() {
cancel()
v.RemoveRay(dest)
}
timer := signal.CancelAfterInactivity(ctx, removeRay, time.Second*4)
link, _ := v.dispatcher.Dispatch(ctx, dest)
entry := &connEntry{
link: link,
timer: timer,
cancel: removeRay,
}
v.conns[dest] = entry
go handleInput(ctx, entry, dest, v.callback)
return entry
}
func (v *Dispatcher) Dispatch(ctx context.Context, destination net.Destination, payload *buf.Buffer) {
// TODO: Add user to destString
newError("dispatch request to: ", destination).AtDebug().WriteToLog(session.ExportIDToError(ctx))
conn := v.getInboundRay(ctx, destination)
outputStream := conn.link.Writer
if outputStream != nil {
if err := outputStream.WriteMultiBuffer(buf.MultiBuffer{payload}); err != nil {
newError("failed to write first UDP payload").Base(err).WriteToLog(session.ExportIDToError(ctx))
conn.cancel()
return
}
}
}
func handleInput(ctx context.Context, conn *connEntry, dest net.Destination, callback ResponseCallback) {
defer conn.cancel()
input := conn.link.Reader
timer := conn.timer
for {
select {
case <-ctx.Done():
return
default:
}
mb, err := input.ReadMultiBuffer()
if err != nil {
newError("failed to handle UDP input").Base(err).WriteToLog(session.ExportIDToError(ctx))
return
}
timer.Update()
for _, b := range mb {
callback(ctx, &udp.Packet{
Payload: b,
Source: dest,
})
}
}
}
type dispatcherConn struct {
dispatcher *Dispatcher
cache chan *udp.Packet
done *done.Instance
}
func DialDispatcher(ctx context.Context, dispatcher routing.Dispatcher) (net.PacketConn, error) {
c := &dispatcherConn{
cache: make(chan *udp.Packet, 16),
done: done.New(),
}
d := NewDispatcher(dispatcher, c.callback)
c.dispatcher = d
return c, nil
}
func (c *dispatcherConn) callback(ctx context.Context, packet *udp.Packet) {
select {
case <-c.done.Wait():
packet.Payload.Release()
return
case c.cache <- packet:
default:
packet.Payload.Release()
return
}
}
func (c *dispatcherConn) ReadFrom(p []byte) (int, net.Addr, error) {
select {
case <-c.done.Wait():
return 0, nil, io.EOF
case packet := <-c.cache:
n := copy(p, packet.Payload.Bytes())
return n, &net.UDPAddr{
IP: packet.Source.Address.IP(),
Port: int(packet.Source.Port),
}, nil
}
}
func (c *dispatcherConn) WriteTo(p []byte, addr net.Addr) (int, error) {
buffer := buf.New()
raw := buffer.Extend(buf.Size)
n := copy(raw, p)
buffer.Resize(0, int32(n))
ctx := context.Background()
c.dispatcher.Dispatch(ctx, net.DestinationFromAddr(addr), buffer)
return n, nil
}
func (c *dispatcherConn) Close() error {
return c.done.Close()
}
func (c *dispatcherConn) LocalAddr() net.Addr {
return &net.UDPAddr{
IP: []byte{0, 0, 0, 0},
Port: 0,
}
}
func (c *dispatcherConn) SetDeadline(t time.Time) error {
return nil
}
func (c *dispatcherConn) SetReadDeadline(t time.Time) error {
return nil
}
func (c *dispatcherConn) SetWriteDeadline(t time.Time) error {
return nil
}
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