71 lines
1.5 KiB
Go
71 lines
1.5 KiB
Go
/*
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* Copyright (C) 2020-2022, IrineSistiana
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*
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* This file is part of mosdns.
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*
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* mosdns is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* mosdns is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package upstream
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import (
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"net"
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"sync/atomic"
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)
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type Event int
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const (
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EventConnOpen Event = iota
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EventConnClose
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)
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type EventObserver interface {
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OnEvent(typ Event)
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}
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type nopEO struct{}
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func (n nopEO) OnEvent(_ Event) {}
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type connWrapper struct {
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net.Conn
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closed atomic.Bool
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ob EventObserver
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}
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// wrapConn wraps c into a connWrapper so that we can observe the connection close.
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// For convenient, if c is nil, wrapConn returns nil as well. If ob is nopEO, wrapConn
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// returns c.
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func wrapConn(c net.Conn, ob EventObserver) net.Conn {
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if c == nil {
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return nil
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}
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if _, ok := ob.(nopEO); ok {
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return c
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}
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ob.OnEvent(EventConnOpen)
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return &connWrapper{
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Conn: c,
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ob: ob,
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}
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}
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func (c *connWrapper) Close() error {
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if c.closed.CompareAndSwap(false, true) {
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c.ob.OnEvent(EventConnClose)
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}
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return c.Conn.Close()
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}
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