cubefs

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// +build !appengine
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/*
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 *
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 * Copyright 2018 gRPC authors.
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 *
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 */
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package credentials
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import (
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	"net"
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	"syscall"
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)
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type sysConn = syscall.Conn
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// syscallConn keeps reference of rawConn to support syscall.Conn for channelz.
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// SyscallConn() (the method in interface syscall.Conn) is explicitly
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// implemented on this type,
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//
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// Interface syscall.Conn is implemented by most net.Conn implementations (e.g.
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// TCPConn, UnixConn), but is not part of net.Conn interface. So wrapper conns
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// that embed net.Conn don't implement syscall.Conn. (Side note: tls.Conn
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// doesn't embed net.Conn, so even if syscall.Conn is part of net.Conn, it won't
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// help here).
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type syscallConn struct {
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	net.Conn
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	// sysConn is a type alias of syscall.Conn. It's necessary because the name
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	// `Conn` collides with `net.Conn`.
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	sysConn
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}
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// WrapSyscallConn tries to wrap rawConn and newConn into a net.Conn that
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// implements syscall.Conn. rawConn will be used to support syscall, and newConn
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// will be used for read/write.
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//
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// This function returns newConn if rawConn doesn't implement syscall.Conn.
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func WrapSyscallConn(rawConn, newConn net.Conn) net.Conn {
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	sysConn, ok := rawConn.(syscall.Conn)
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	if !ok {
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		return newConn
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	}
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	return &syscallConn{
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		Conn:    newConn,
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		sysConn: sysConn,
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	}
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}
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