listener.go

Documentation: github.com/docker/distribution/registry/listener

     1  package listener
     2  
     3  import (
     4  	"fmt"
     5  	"net"
     6  	"os"
     7  	"time"
     8  )
     9  
    10  // tcpKeepAliveListener sets TCP keep-alive timeouts on accepted
    11  // connections. It's used by ListenAndServe and ListenAndServeTLS so
    12  // dead TCP connections (e.g. closing laptop mid-download) eventually
    13  // go away.
    14  // it is a plain copy-paste from net/http/server.go
    15  type tcpKeepAliveListener struct {
    16  	*net.TCPListener
    17  }
    18  
    19  func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
    20  	tc, err := ln.AcceptTCP()
    21  	if err != nil {
    22  		return
    23  	}
    24  	tc.SetKeepAlive(true)
    25  	tc.SetKeepAlivePeriod(3 * time.Minute)
    26  	return tc, nil
    27  }
    28  
    29  // NewListener announces on laddr and net. Accepted values of the net are
    30  // 'unix' and 'tcp'
    31  func NewListener(net, laddr string) (net.Listener, error) {
    32  	switch net {
    33  	case "unix":
    34  		return newUnixListener(laddr)
    35  	case "tcp", "": // an empty net means tcp
    36  		return newTCPListener(laddr)
    37  	default:
    38  		return nil, fmt.Errorf("unknown address type %s", net)
    39  	}
    40  }
    41  
    42  func newUnixListener(laddr string) (net.Listener, error) {
    43  	fi, err := os.Stat(laddr)
    44  	if err == nil {
    45  		// the file exists.
    46  		// try to remove it if it's a socket
    47  		if !isSocket(fi.Mode()) {
    48  			return nil, fmt.Errorf("file %s exists and is not a socket", laddr)
    49  		}
    50  
    51  		if err := os.Remove(laddr); err != nil {
    52  			return nil, err
    53  		}
    54  	} else if !os.IsNotExist(err) {
    55  		// we can't do stat on the file.
    56  		// it means we can not remove it
    57  		return nil, err
    58  	}
    59  
    60  	return net.Listen("unix", laddr)
    61  }
    62  
    63  func isSocket(m os.FileMode) bool {
    64  	return m&os.ModeSocket != 0
    65  }
    66  
    67  func newTCPListener(laddr string) (net.Listener, error) {
    68  	ln, err := net.Listen("tcp", laddr)
    69  	if err != nil {
    70  		return nil, err
    71  	}
    72  
    73  	return tcpKeepAliveListener{ln.(*net.TCPListener)}, nil
    74  }
    75
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