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moby--moby/client/hijack.go

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package client // import "github.com/docker/docker/client"
import (
"bufio"
"crypto/tls"
"fmt"
"net"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"time"
"github.com/docker/docker/api/types"
"github.com/docker/go-connections/sockets"
"github.com/pkg/errors"
"golang.org/x/net/context"
)
// tlsClientCon holds tls information and a dialed connection.
type tlsClientCon struct {
*tls.Conn
rawConn net.Conn
}
func (c *tlsClientCon) CloseWrite() error {
// Go standard tls.Conn doesn't provide the CloseWrite() method so we do it
// on its underlying connection.
if conn, ok := c.rawConn.(types.CloseWriter); ok {
return conn.CloseWrite()
}
return nil
}
// postHijacked sends a POST request and hijacks the connection.
func (cli *Client) postHijacked(ctx context.Context, path string, query url.Values, body interface{}, headers map[string][]string) (types.HijackedResponse, error) {
bodyEncoded, err := encodeData(body)
if err != nil {
return types.HijackedResponse{}, err
}
apiPath := cli.getAPIPath(path, query)
req, err := http.NewRequest("POST", apiPath, bodyEncoded)
if err != nil {
return types.HijackedResponse{}, err
}
req = cli.addHeaders(req, headers)
conn, err := cli.setupHijackConn(req, "tcp")
if err != nil {
return types.HijackedResponse{}, err
}
return types.HijackedResponse{Conn: conn, Reader: bufio.NewReader(conn)}, err
}
func tlsDial(network, addr string, config *tls.Config) (net.Conn, error) {
return tlsDialWithDialer(new(net.Dialer), network, addr, config)
}
// We need to copy Go's implementation of tls.Dial (pkg/cryptor/tls/tls.go) in
// order to return our custom tlsClientCon struct which holds both the tls.Conn
// object _and_ its underlying raw connection. The rationale for this is that
// we need to be able to close the write end of the connection when attaching,
// which tls.Conn does not provide.
func tlsDialWithDialer(dialer *net.Dialer, network, addr string, config *tls.Config) (net.Conn, error) {
// We want the Timeout and Deadline values from dialer to cover the
// whole process: TCP connection and TLS handshake. This means that we
// also need to start our own timers now.
timeout := dialer.Timeout
if !dialer.Deadline.IsZero() {
deadlineTimeout := time.Until(dialer.Deadline)
if timeout == 0 || deadlineTimeout < timeout {
timeout = deadlineTimeout
}
}
var errChannel chan error
if timeout != 0 {
errChannel = make(chan error, 2)
time.AfterFunc(timeout, func() {
errChannel <- errors.New("")
})
}
proxyDialer, err := sockets.DialerFromEnvironment(dialer)
if err != nil {
return nil, err
}
rawConn, err := proxyDialer.Dial(network, addr)
if err != nil {
return nil, err
}
// When we set up a TCP connection for hijack, there could be long periods
// of inactivity (a long running command with no output) that in certain
// network setups may cause ECONNTIMEOUT, leaving the client in an unknown
// state. Setting TCP KeepAlive on the socket connection will prohibit
// ECONNTIMEOUT unless the socket connection truly is broken
if tcpConn, ok := rawConn.(*net.TCPConn); ok {
tcpConn.SetKeepAlive(true)
tcpConn.SetKeepAlivePeriod(30 * time.Second)
}
colonPos := strings.LastIndex(addr, ":")
if colonPos == -1 {
colonPos = len(addr)
}
hostname := addr[:colonPos]
// If no ServerName is set, infer the ServerName
// from the hostname we're connecting to.
if config.ServerName == "" {
// Make a copy to avoid polluting argument or default.
config = tlsConfigClone(config)
config.ServerName = hostname
}
conn := tls.Client(rawConn, config)
if timeout == 0 {
err = conn.Handshake()
} else {
go func() {
errChannel <- conn.Handshake()
}()
err = <-errChannel
}
if err != nil {
rawConn.Close()
return nil, err
}
// This is Docker difference with standard's crypto/tls package: returned a
// wrapper which holds both the TLS and raw connections.
return &tlsClientCon{conn, rawConn}, nil
}
func dial(proto, addr string, tlsConfig *tls.Config) (net.Conn, error) {
if tlsConfig != nil && proto != "unix" && proto != "npipe" {
// Notice this isn't Go standard's tls.Dial function
return tlsDial(proto, addr, tlsConfig)
}
if proto == "npipe" {
return sockets.DialPipe(addr, 32*time.Second)
}
return net.Dial(proto, addr)
}
func (cli *Client) setupHijackConn(req *http.Request, proto string) (net.Conn, error) {
req.Host = cli.addr
req.Header.Set("Connection", "Upgrade")
req.Header.Set("Upgrade", proto)
conn, err := dial(cli.proto, cli.addr, resolveTLSConfig(cli.client.Transport))
if err != nil {
return nil, errors.Wrap(err, "cannot connect to the Docker daemon. Is 'docker daemon' running on this host?")
}
// When we set up a TCP connection for hijack, there could be long periods
// of inactivity (a long running command with no output) that in certain
// network setups may cause ECONNTIMEOUT, leaving the client in an unknown
// state. Setting TCP KeepAlive on the socket connection will prohibit
// ECONNTIMEOUT unless the socket connection truly is broken
if tcpConn, ok := conn.(*net.TCPConn); ok {
tcpConn.SetKeepAlive(true)
tcpConn.SetKeepAlivePeriod(30 * time.Second)
}
clientconn := httputil.NewClientConn(conn, nil)
defer clientconn.Close()
// Server hijacks the connection, error 'connection closed' expected
resp, err := clientconn.Do(req)
if err != httputil.ErrPersistEOF {
if err != nil {
return nil, err
}
if resp.StatusCode != http.StatusSwitchingProtocols {
resp.Body.Close()
return nil, fmt.Errorf("unable to upgrade to %s, received %d", proto, resp.StatusCode)
}
}
c, br := clientconn.Hijack()
if br.Buffered() > 0 {
// If there is buffered content, wrap the connection. We return an
// object that implements CloseWrite iff the underlying connection
// implements it.
if _, ok := c.(types.CloseWriter); ok {
c = &hijackedConnCloseWriter{&hijackedConn{c, br}}
} else {
c = &hijackedConn{c, br}
}
} else {
br.Reset(nil)
}
return c, nil
}
// hijackedConn wraps a net.Conn and is returned by setupHijackConn in the case
// that a) there was already buffered data in the http layer when Hijack() was
// called, and b) the underlying net.Conn does *not* implement CloseWrite().
// hijackedConn does not implement CloseWrite() either.
type hijackedConn struct {
net.Conn
r *bufio.Reader
}
func (c *hijackedConn) Read(b []byte) (int, error) {
return c.r.Read(b)
}
// hijackedConnCloseWriter is a hijackedConn which additionally implements
// CloseWrite(). It is returned by setupHijackConn in the case that a) there
// was already buffered data in the http layer when Hijack() was called, and b)
// the underlying net.Conn *does* implement CloseWrite().
type hijackedConnCloseWriter struct {
*hijackedConn
}
var _ types.CloseWriter = &hijackedConnCloseWriter{}
func (c *hijackedConnCloseWriter) CloseWrite() error {
conn := c.Conn.(types.CloseWriter)
return conn.CloseWrite()
}