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