github.com/hxx258456/ccgo@v0.0.5-0.20230213014102-48b35f46f66f/grpc/internal/credentials/syscallconn.go (about)

     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  }