github.com/noxiouz/docker@v0.7.3-0.20160629055221-3d231c78e8c5/pkg/proxy/tcp_proxy.go (about)

     1  package proxy
     2  
     3  import (
     4  	"io"
     5  	"net"
     6  	"sync"
     7  	"syscall"
     8  
     9  	"github.com/Sirupsen/logrus"
    10  )
    11  
    12  // TCPProxy is a proxy for TCP connections. It implements the Proxy interface to
    13  // handle TCP traffic forwarding between the frontend and backend addresses.
    14  type TCPProxy struct {
    15  	listener     *net.TCPListener
    16  	frontendAddr *net.TCPAddr
    17  	backendAddr  *net.TCPAddr
    18  }
    19  
    20  // NewTCPProxy creates a new TCPProxy.
    21  func NewTCPProxy(frontendAddr, backendAddr *net.TCPAddr) (*TCPProxy, error) {
    22  	listener, err := net.ListenTCP("tcp", frontendAddr)
    23  	if err != nil {
    24  		return nil, err
    25  	}
    26  	// If the port in frontendAddr was 0 then ListenTCP will have a picked
    27  	// a port to listen on, hence the call to Addr to get that actual port:
    28  	return &TCPProxy{
    29  		listener:     listener,
    30  		frontendAddr: listener.Addr().(*net.TCPAddr),
    31  		backendAddr:  backendAddr,
    32  	}, nil
    33  }
    34  
    35  func (proxy *TCPProxy) clientLoop(client *net.TCPConn, quit chan bool) {
    36  	backend, err := net.DialTCP("tcp", nil, proxy.backendAddr)
    37  	if err != nil {
    38  		logrus.Printf("Can't forward traffic to backend tcp/%v: %s\n", proxy.backendAddr, err)
    39  		client.Close()
    40  		return
    41  	}
    42  
    43  	var wg sync.WaitGroup
    44  	var broker = func(to, from *net.TCPConn) {
    45  		if _, err := io.Copy(to, from); err != nil {
    46  			// If the socket we are writing to is shutdown with
    47  			// SHUT_WR, forward it to the other end of the pipe:
    48  			if err, ok := err.(*net.OpError); ok && err.Err == syscall.EPIPE {
    49  				from.CloseWrite()
    50  			}
    51  		}
    52  		to.CloseRead()
    53  		wg.Done()
    54  	}
    55  
    56  	wg.Add(2)
    57  	go broker(client, backend)
    58  	go broker(backend, client)
    59  
    60  	finish := make(chan struct{})
    61  	go func() {
    62  		wg.Wait()
    63  		close(finish)
    64  	}()
    65  
    66  	select {
    67  	case <-quit:
    68  	case <-finish:
    69  	}
    70  	client.Close()
    71  	backend.Close()
    72  	<-finish
    73  }
    74  
    75  // Run starts forwarding the traffic using TCP.
    76  func (proxy *TCPProxy) Run() {
    77  	quit := make(chan bool)
    78  	defer close(quit)
    79  	for {
    80  		client, err := proxy.listener.Accept()
    81  		if err != nil {
    82  			logrus.Printf("Stopping proxy on tcp/%v for tcp/%v (%s)", proxy.frontendAddr, proxy.backendAddr, err)
    83  			return
    84  		}
    85  		go proxy.clientLoop(client.(*net.TCPConn), quit)
    86  	}
    87  }
    88  
    89  // Close stops forwarding the traffic.
    90  func (proxy *TCPProxy) Close() { proxy.listener.Close() }
    91  
    92  // FrontendAddr returns the TCP address on which the proxy is listening.
    93  func (proxy *TCPProxy) FrontendAddr() net.Addr { return proxy.frontendAddr }
    94  
    95  // BackendAddr returns the TCP proxied address.
    96  func (proxy *TCPProxy) BackendAddr() net.Addr { return proxy.backendAddr }