package client // import "github.com/docker/docker/client" import ( "bufio" "context" "crypto/tls" "fmt" "net" "net/http" "net/http/httputil" "net/url" "time" "github.com/docker/docker/api/types" "github.com/docker/go-connections/sockets" "github.com/pkg/errors" ) // 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(ctx, req, "tcp") if err != nil { return types.HijackedResponse{}, err } return types.HijackedResponse{Conn: conn, Reader: bufio.NewReader(conn)}, err } // DialHijack returns a hijacked connection with negotiated protocol proto. func (cli *Client) DialHijack(ctx context.Context, url, proto string, meta map[string][]string) (net.Conn, error) { req, err := http.NewRequest("POST", url, nil) if err != nil { return nil, err } req = cli.addHeaders(req, meta) return cli.setupHijackConn(ctx, req, proto) } // fallbackDial is used when WithDialer() was not called. // See cli.Dialer(). func fallbackDial(proto, addr string, tlsConfig *tls.Config) (net.Conn, error) { if tlsConfig != nil && proto != "unix" && proto != "npipe" { return tls.Dial(proto, addr, tlsConfig) } if proto == "npipe" { return sockets.DialPipe(addr, 32*time.Second) } return net.Dial(proto, addr) } func (cli *Client) setupHijackConn(ctx context.Context, req *http.Request, proto string) (net.Conn, error) { req.Host = cli.addr req.Header.Set("Connection", "Upgrade") req.Header.Set("Upgrade", proto) dialer := cli.Dialer() conn, err := dialer(ctx) 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() }