package dialer import ( "context" "io" "net" "os" "time" "github.com/sagernet/sing/common" "github.com/sagernet/sing/common/bufio" E "github.com/sagernet/sing/common/exceptions" M "github.com/sagernet/sing/common/metadata" N "github.com/sagernet/sing/common/network" "github.com/sagernet/tfo-go" ) type slowOpenConn struct { dialer *tfo.Dialer ctx context.Context network string destination M.Socksaddr conn net.Conn create chan struct{} err error } func DialSlowContext(dialer *tfo.Dialer, ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) { if dialer.DisableTFO || N.NetworkName(network) != N.NetworkTCP { switch N.NetworkName(network) { case N.NetworkTCP, N.NetworkUDP: return dialer.Dialer.DialContext(ctx, network, destination.String()) default: return dialer.Dialer.DialContext(ctx, network, destination.AddrString()) } } return &slowOpenConn{ dialer: dialer, ctx: ctx, network: network, destination: destination, create: make(chan struct{}), }, nil } func (c *slowOpenConn) Read(b []byte) (n int, err error) { if c.conn == nil { select { case <-c.create: if c.err != nil { return 0, c.err } case <-c.ctx.Done(): return 0, c.ctx.Err() } } return c.conn.Read(b) } func (c *slowOpenConn) Write(b []byte) (n int, err error) { if c.conn == nil { c.conn, err = c.dialer.DialContext(c.ctx, c.network, c.destination.String(), b) if err != nil { c.err = E.Cause(err, "dial tcp fast open") } close(c.create) return } return c.conn.Write(b) } func (c *slowOpenConn) Close() error { return common.Close(c.conn) } func (c *slowOpenConn) LocalAddr() net.Addr { if c.conn == nil { return M.Socksaddr{} } return c.conn.LocalAddr() } func (c *slowOpenConn) RemoteAddr() net.Addr { if c.conn == nil { return M.Socksaddr{} } return c.conn.RemoteAddr() } func (c *slowOpenConn) SetDeadline(t time.Time) error { if c.conn == nil { return os.ErrInvalid } return c.conn.SetDeadline(t) } func (c *slowOpenConn) SetReadDeadline(t time.Time) error { if c.conn == nil { return os.ErrInvalid } return c.conn.SetReadDeadline(t) } func (c *slowOpenConn) SetWriteDeadline(t time.Time) error { if c.conn == nil { return os.ErrInvalid } return c.conn.SetWriteDeadline(t) } func (c *slowOpenConn) Upstream() any { return c.conn } func (c *slowOpenConn) ReaderReplaceable() bool { return c.conn != nil } func (c *slowOpenConn) WriterReplaceable() bool { return c.conn != nil } func (c *slowOpenConn) LazyHeadroom() bool { return c.conn == nil } func (c *slowOpenConn) NeedHandshake() bool { return c.conn == nil } func (c *slowOpenConn) WriteTo(w io.Writer) (n int64, err error) { if c.conn == nil { select { case <-c.create: if c.err != nil { return 0, c.err } case <-c.ctx.Done(): return 0, c.ctx.Err() } } return bufio.Copy(w, c.conn) }