@@ -44,7 +44,6 @@ type stateBackend interface {

 	ContainerUnpause(name string) error

 	ContainerWait(name string, timeout time.Duration) (int, error)

 	Exists(id string) bool

-	IsPaused(id string) bool

 }

 // monitorBackend includes functions to implement to provide containers monitoring functionality.

@@ -400,29 +400,11 @@ func (s *containerRouter) postContainersAttach(ctx context.Context, w http.Respo

 	}

 	containerName := vars["name"]

-	if !s.backend.Exists(containerName) {

-		return derr.ErrorCodeNoSuchContainer.WithArgs(containerName)

-	}

-

-	if s.backend.IsPaused(containerName) {

-		return derr.ErrorCodePausedContainer.WithArgs(containerName)

-	}

-

-	inStream, outStream, err := httputils.HijackConnection(w)

-	if err != nil {

-		return err

-	}

-	defer httputils.CloseStreams(inStream, outStream)

-

-	if _, ok := r.Header["Upgrade"]; ok {

-		fmt.Fprintf(outStream, "HTTP/1.1 101 UPGRADED\r\nContent-Type: application/vnd.docker.raw-stream\r\nConnection: Upgrade\r\nUpgrade: tcp\r\n\r\n")

-	} else {

-		fmt.Fprintf(outStream, "HTTP/1.1 200 OK\r\nContent-Type: application/vnd.docker.raw-stream\r\n\r\n")

-	}

+	_, upgrade := r.Header["Upgrade"]

 	attachWithLogsConfig := &daemon.ContainerAttachWithLogsConfig{

-		InStream:  inStream,

-		OutStream: outStream,

+		Hijacker:  w.(http.Hijacker),

+		Upgrade:   upgrade,

 		UseStdin:  httputils.BoolValue(r, "stdin"),

 		UseStdout: httputils.BoolValue(r, "stdout"),

 		UseStderr: httputils.BoolValue(r, "stderr"),

@@ -430,11 +412,7 @@ func (s *containerRouter) postContainersAttach(ctx context.Context, w http.Respo

 		Stream:    httputils.BoolValue(r, "stream"),

 	}

-	if err := s.backend.ContainerAttachWithLogs(containerName, attachWithLogsConfig); err != nil {

-		fmt.Fprintf(outStream, "Error attaching: %s\n", err)

-	}

-

-	return nil

+	return s.backend.ContainerAttachWithLogs(containerName, attachWithLogsConfig)

 }

 func (s *containerRouter) wsContainersAttach(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {

@@ -1,53 +1,84 @@

 package daemon

 import (

+	"fmt"

 	"io"

+	"net/http"

 	"time"

 	"github.com/Sirupsen/logrus"

 	"github.com/docker/docker/container"

 	"github.com/docker/docker/daemon/logger"

+	derr "github.com/docker/docker/errors"

 	"github.com/docker/docker/pkg/stdcopy"

 )

 // ContainerAttachWithLogsConfig holds the streams to use when connecting to a container to view logs.

 type ContainerAttachWithLogsConfig struct {

-	InStream                       io.ReadCloser

-	OutStream                      io.Writer

-	UseStdin, UseStdout, UseStderr bool

-	Logs, Stream                   bool

+	Hijacker  http.Hijacker

+	Upgrade   bool

+	UseStdin  bool

+	UseStdout bool

+	UseStderr bool

+	Logs      bool

+	Stream    bool

 }

 // ContainerAttachWithLogs attaches to logs according to the config passed in. See ContainerAttachWithLogsConfig.

 func (daemon *Daemon) ContainerAttachWithLogs(prefixOrName string, c *ContainerAttachWithLogsConfig) error {

+	if c.Hijacker == nil {

+		return derr.ErrorCodeNoHijackConnection.WithArgs(prefixOrName)

+	}

 	container, err := daemon.GetContainer(prefixOrName)

 	if err != nil {

+		return derr.ErrorCodeNoSuchContainer.WithArgs(prefixOrName)

+	}

+	if container.IsPaused() {

+		return derr.ErrorCodePausedContainer.WithArgs(prefixOrName)

+	}

+

+	conn, _, err := c.Hijacker.Hijack()

+	if err != nil {

 		return err

 	}

+	defer conn.Close()

+	// Flush the options to make sure the client sets the raw mode

+	conn.Write([]byte{})

+	inStream := conn.(io.ReadCloser)

+	outStream := conn.(io.Writer)

+

+	if c.Upgrade {

+		fmt.Fprintf(outStream, "HTTP/1.1 101 UPGRADED\r\nContent-Type: application/vnd.docker.raw-stream\r\nConnection: Upgrade\r\nUpgrade: tcp\r\n\r\n")

+	} else {

+		fmt.Fprintf(outStream, "HTTP/1.1 200 OK\r\nContent-Type: application/vnd.docker.raw-stream\r\n\r\n")

+	}

 	var errStream io.Writer

 	if !container.Config.Tty {

-		errStream = stdcopy.NewStdWriter(c.OutStream, stdcopy.Stderr)

-		c.OutStream = stdcopy.NewStdWriter(c.OutStream, stdcopy.Stdout)

+		errStream = stdcopy.NewStdWriter(outStream, stdcopy.Stderr)

+		outStream = stdcopy.NewStdWriter(outStream, stdcopy.Stdout)

 	} else {

-		errStream = c.OutStream

+		errStream = outStream

 	}

 	var stdin io.ReadCloser

 	var stdout, stderr io.Writer

 	if c.UseStdin {

-		stdin = c.InStream

+		stdin = inStream

 	}

 	if c.UseStdout {

-		stdout = c.OutStream

+		stdout = outStream

 	}

 	if c.UseStderr {

 		stderr = errStream

 	}

-	return daemon.attachWithLogs(container, stdin, stdout, stderr, c.Logs, c.Stream)

+	if err := daemon.attachWithLogs(container, stdin, stdout, stderr, c.Logs, c.Stream); err != nil {

+		fmt.Fprintf(outStream, "Error attaching: %s\n", err)

+	}

+	return nil

 }

 // ContainerWsAttachWithLogsConfig attach with websockets, since all

@@ -33,4 +33,13 @@ var (

 		Description:    "Docker's networking stack is disabled for this platform",

 		HTTPStatusCode: http.StatusNotFound,

 	})

+

+	// ErrorCodeNoHijackConnection is generated when a request tries to attach to a container

+	// but the connection to hijack is not provided.

+	ErrorCodeNoHijackConnection = errcode.Register(errGroup, errcode.ErrorDescriptor{

+		Value:          "HIJACK_CONNECTION_MISSING",

+		Message:        "error attaching to container %s, hijack connection missing",

+		Description:    "The caller didn't provide a connection to hijack",

+		HTTPStatusCode: http.StatusBadRequest,

+	})

 )