streamlocal.go

Documentation: golang.org/x/crypto/ssh

     1  package ssh
     2  
     3  import (
     4  	"errors"
     5  	"io"
     6  	"net"
     7  )
     8  
     9  // streamLocalChannelOpenDirectMsg is a struct used for SSH_MSG_CHANNEL_OPEN message
    10  // with "direct-streamlocal@openssh.com" string.
    11  //
    12  // See openssh-portable/PROTOCOL, section 2.4. connection: Unix domain socket forwarding
    13  // https://github.com/openssh/openssh-portable/blob/master/PROTOCOL#L235
    14  type streamLocalChannelOpenDirectMsg struct {
    15  	socketPath string
    16  	reserved0  string
    17  	reserved1  uint32
    18  }
    19  
    20  // forwardedStreamLocalPayload is a struct used for SSH_MSG_CHANNEL_OPEN message
    21  // with "forwarded-streamlocal@openssh.com" string.
    22  type forwardedStreamLocalPayload struct {
    23  	SocketPath string
    24  	Reserved0  string
    25  }
    26  
    27  // streamLocalChannelForwardMsg is a struct used for SSH2_MSG_GLOBAL_REQUEST message
    28  // with "streamlocal-forward@openssh.com"/"cancel-streamlocal-forward@openssh.com" string.
    29  type streamLocalChannelForwardMsg struct {
    30  	socketPath string
    31  }
    32  
    33  // ListenUnix is similar to ListenTCP but uses a Unix domain socket.
    34  func (c *Client) ListenUnix(socketPath string) (net.Listener, error) {
    35  	c.handleForwardsOnce.Do(c.handleForwards)
    36  	m := streamLocalChannelForwardMsg{
    37  		socketPath,
    38  	}
    39  	// send message
    40  	ok, _, err := c.SendRequest("streamlocal-forward@openssh.com", true, Marshal(&m))
    41  	if err != nil {
    42  		return nil, err
    43  	}
    44  	if !ok {
    45  		return nil, errors.New("ssh: streamlocal-forward@openssh.com request denied by peer")
    46  	}
    47  	ch := c.forwards.add(&net.UnixAddr{Name: socketPath, Net: "unix"})
    48  
    49  	return &unixListener{socketPath, c, ch}, nil
    50  }
    51  
    52  func (c *Client) dialStreamLocal(socketPath string) (Channel, error) {
    53  	msg := streamLocalChannelOpenDirectMsg{
    54  		socketPath: socketPath,
    55  	}
    56  	ch, in, err := c.OpenChannel("direct-streamlocal@openssh.com", Marshal(&msg))
    57  	if err != nil {
    58  		return nil, err
    59  	}
    60  	go DiscardRequests(in)
    61  	return ch, err
    62  }
    63  
    64  type unixListener struct {
    65  	socketPath string
    66  
    67  	conn *Client
    68  	in   <-chan forward
    69  }
    70  
    71  // Accept waits for and returns the next connection to the listener.
    72  func (l *unixListener) Accept() (net.Conn, error) {
    73  	s, ok := <-l.in
    74  	if !ok {
    75  		return nil, io.EOF
    76  	}
    77  	ch, incoming, err := s.newCh.Accept()
    78  	if err != nil {
    79  		return nil, err
    80  	}
    81  	go DiscardRequests(incoming)
    82  
    83  	return &chanConn{
    84  		Channel: ch,
    85  		laddr: &net.UnixAddr{
    86  			Name: l.socketPath,
    87  			Net:  "unix",
    88  		},
    89  		raddr: &net.UnixAddr{
    90  			Name: "@",
    91  			Net:  "unix",
    92  		},
    93  	}, nil
    94  }
    95  
    96  // Close closes the listener.
    97  func (l *unixListener) Close() error {
    98  	// this also closes the listener.
    99  	l.conn.forwards.remove(&net.UnixAddr{Name: l.socketPath, Net: "unix"})
   100  	m := streamLocalChannelForwardMsg{
   101  		l.socketPath,
   102  	}
   103  	ok, _, err := l.conn.SendRequest("cancel-streamlocal-forward@openssh.com", true, Marshal(&m))
   104  	if err == nil && !ok {
   105  		err = errors.New("ssh: cancel-streamlocal-forward@openssh.com failed")
   106  	}
   107  	return err
   108  }
   109  
   110  // Addr returns the listener's network address.
   111  func (l *unixListener) Addr() net.Addr {
   112  	return &net.UnixAddr{
   113  		Name: l.socketPath,
   114  		Net:  "unix",
   115  	}
   116  }
   117
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