1 /*
2 *
3 * Copyright 2018 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18 19 package credentials
20 21 import (
22 "net"
23 "syscall"
24 )
25 26 type sysConn = syscall.Conn
27 28 // syscallConn keeps reference of rawConn to support syscall.Conn for channelz.
29 // SyscallConn() (the method in interface syscall.Conn) is explicitly
30 // implemented on this type,
31 //
32 // Interface syscall.Conn is implemented by most net.Conn implementations (e.g.
33 // TCPConn, UnixConn), but is not part of net.Conn interface. So wrapper conns
34 // that embed net.Conn don't implement syscall.Conn. (Side note: tls.Conn
35 // doesn't embed net.Conn, so even if syscall.Conn is part of net.Conn, it won't
36 // help here).
37 type syscallConn struct {
38 net.Conn
39 // sysConn is a type alias of syscall.Conn. It's necessary because the name
40 // `Conn` collides with `net.Conn`.
41 sysConn
42 }
43 44 // WrapSyscallConn tries to wrap rawConn and newConn into a net.Conn that
45 // implements syscall.Conn. rawConn will be used to support syscall, and newConn
46 // will be used for read/write.
47 //
48 // This function returns newConn if rawConn doesn't implement syscall.Conn.
49 func WrapSyscallConn(rawConn, newConn net.Conn) net.Conn {
50 sysConn, ok := rawConn.(syscall.Conn)
51 if !ok {
52 return newConn
53 }
54 return &syscallConn{
55 Conn: newConn,
56 sysConn: sysConn,
57 }
58 }
59