chore: Add read deadline implementation

common/net/sing.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/bufio"
+	"github.com/sagernet/sing/common/bufio/deadline"
 	"github.com/sagernet/sing/common/network"
 )
 
@@ -17,6 +18,20 @@ type ExtendedConn = network.ExtendedConn
 type ExtendedWriter = network.ExtendedWriter
 type ExtendedReader = network.ExtendedReader
 
+func NewDeadlineConn(conn net.Conn) ExtendedConn {
+	if dc, ok := conn.(*deadline.Conn); ok {
+		return dc
+	}
+	return deadline.NewConn(conn)
+}
+
+func NewDeadlinePacketConn(pc net.PacketConn) net.PacketConn {
+	if dpc, ok := pc.(*deadline.PacketConn); ok {
+		return dpc
+	}
+	return deadline.NewPacketConn(bufio.NewPacketConn(pc))
+}
+
 func NeedHandshake(conn any) bool {
 	if earlyConn, isEarlyConn := common.Cast[network.EarlyConn](conn); isEarlyConn && earlyConn.NeedHandshake() {
 		return true