Merge 5fc1b0629c into fee5291495

conmon/conmon.c

@@ -12,10 +12,12 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <sys/un.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/eventfd.h>
 #include <sys/stat.h>
 #include <sys/uio.h>
+#include <sys/ioctl.h>
 #include <syslog.h>
 #include <unistd.h>
 
@@ -23,6 +25,8 @@
 
 #include "cmsg.h"
 
+#include "pollset.h"
+
 #define pexit(fmt, ...)                                                          \
 	do {                                                                     \
 		fprintf(stderr, "[conmon:e]: " fmt " %m\n", ##__VA_ARGS__);      \
@@ -40,11 +44,13 @@
 #define nwarn(fmt, ...)                                                        \
 	do {                                                                   \
 		fprintf(stderr, "[conmon:w]: " fmt "\n", ##__VA_ARGS__);       \
+		syslog(LOG_INFO, "conmon <nwarn>: " fmt " \n", ##__VA_ARGS__); \
 	} while (0)
 
 #define ninfo(fmt, ...)                                                        \
 	do {                                                                   \
 		fprintf(stderr, "[conmon:i]: " fmt "\n", ##__VA_ARGS__);       \
+		syslog(LOG_INFO, "conmon <ninfo>: " fmt " \n", ##__VA_ARGS__); \
 	} while (0)
 
 #define _cleanup_(x) __attribute__((cleanup(x)))
@@ -428,21 +434,182 @@ static char *escape_json_string(const char *str)
 	return g_string_free (escaped, FALSE);
 }
 
+/* Global state */
+
+static int masterfd_stdout = -1;
+static int masterfd_stderr = -1;
+static int num_stdio_fds = 0;
+
+/* Used for attach */
+static int conn_sock = -1;
+
+static int logfd = -1;
+static int efd = -1;
+static int cfd = -1;
+/* Used for OOM notification API */
+static int ofd = -1;
+
+
+static void stdio_input (G_GNUC_UNUSED polling_set_t *set, int fd, gpointer user_data)
+{
+	char buf[BUF_SIZE];
+	stdpipe_t pipe = GPOINTER_TO_INT(user_data);
+	ssize_t num_read;
+
+	num_read = read(fd, buf, BUF_SIZE);
+	if (num_read <= 0) {
+		nwarn("stdio_input read failed");
+		return;
+	}
+
+	if (write_k8s_log(logfd, pipe, buf, num_read) < 0) {
+		nwarn("write_k8s_log failed");
+		return;
+	}
+
+	if (conn_sock > 0) {
+		if (write_all(conn_sock, buf, num_read) < 0) {
+			nwarn("Failed to write to socket");
+		}
+	}
+}
+
+static bool stdio_error (G_GNUC_UNUSED polling_set_t *set, int fd, gpointer user_data)
+{
+	stdpipe_t pipe = GPOINTER_TO_INT(user_data);
+	printf("closing stdio fd %d\n", fd);
+	if (pipe == STDOUT_PIPE)
+		masterfd_stdout = -1;
+	if (pipe == STDERR_PIPE)
+		masterfd_stderr = -1;
+	num_stdio_fds--;
+	return true;
+}
+
+static void oom_input (G_GNUC_UNUSED polling_set_t *set, int fd, G_GNUC_UNUSED gpointer user_data)
+{
+	uint64_t oom_event;
+
+	if (read(fd, &oom_event, sizeof(uint64_t)) != sizeof(uint64_t))
+		nwarn("Failed to read event from eventfd");
+	ninfo("OOM received");
+	if (open("oom", O_CREAT, 0666) < 0) {
+		nwarn("Failed to write oom file");
+	}
+}
+
+static void conn_sock_input (G_GNUC_UNUSED polling_set_t *set, int fd, G_GNUC_UNUSED gpointer user_data)
+{
+	ssize_t num_read;
+	char buf[BUF_SIZE];
+
+	num_read = read(fd, buf, BUF_SIZE);
+	if (num_read <= 0)
+		return;
+	ninfo("got data on connection: %zd", num_read);
+	if (terminal) {
+		if (write_all(masterfd_stdout, buf, num_read) < 0) {
+			nwarn("Failed to write to master pty");
+		}
+	}
+}
+
+static bool conn_sock_error (G_GNUC_UNUSED polling_set_t *set, G_GNUC_UNUSED int fd, G_GNUC_UNUSED gpointer user_data)
+{
+	conn_sock = -1;
+	return true;
+}
+
+static void attach_input (polling_set_t *set, int fd, G_GNUC_UNUSED gpointer user_data)
+{
+	conn_sock = accept(fd, NULL, NULL);
+	if (conn_sock == -1) {
+		nwarn("Failed to accept client connection on attach socket");
+		return;
+	}
+	if (polling_set_add_fd(set, conn_sock, conn_sock_input, conn_sock_error, NULL) < 0)
+		pexit("Failed to add client socket fd to epoll");
+	ninfo("Accepted connection");
+}
+
+static void ctl_input (G_GNUC_UNUSED polling_set_t *set, int fd, G_GNUC_UNUSED gpointer user_data)
+{
+	#define CTLBUFSZ 200
+	static char ctlbuf[CTLBUFSZ];
+	static int readsz = CTLBUFSZ - 1;
+	static char *readptr = ctlbuf;
+	ssize_t num_read;
+	int ctl_msg_type = -1;
+	int height = -1;
+	int width = -1;
+	struct winsize ws;
+	int ret;
+
+	num_read = read(fd, readptr, readsz);
+	if (num_read <= 0) {
+		nwarn("Failed to read from control fd");
+		return;
+	}
+	readptr[num_read] = '\0';
+	ninfo("Got ctl message: %s\n", ctlbuf);
+
+	char *beg = ctlbuf;
+	char *newline = strchrnul(beg, '\n');
+	/* Process each message which ends with a line */
+	while (*newline != '\0') {
+		ret = sscanf(ctlbuf, "%d %d %d\n", &ctl_msg_type, &height, &width);
+		if (ret != 3) {
+			nwarn("Failed to sscanf message");
+			continue;
+		}
+		ninfo("Message type: %d, Height: %d, Width: %d", ctl_msg_type, height, width);
+		ret = ioctl(masterfd_stdout, TIOCGWINSZ, &ws);
+		ninfo("Existing size: %d %d", ws.ws_row, ws.ws_col);
+		ws.ws_row = height;
+		ws.ws_col = width;
+		ret = ioctl(masterfd_stdout, TIOCSWINSZ, &ws);
+		if (ret == -1) {
+			nwarn("Failed to set process pty terminal size");
+		}
+		beg = newline + 1;
+		newline = strchrnul(beg, '\n');
+	}
+	if (*beg == '\0') {
+		/* We exhausted all messages that were complete */
+		readptr = ctlbuf;
+		readsz = CTLBUFSZ - 1;
+	} else {
+		/*
+		 * We copy remaining data to beginning of buffer
+		 * and advance readptr after that.
+		 */
+		int cp_rem = 0;
+		do {
+			ctlbuf[cp_rem++] = *beg++;
+		} while (*beg != '\0');
+		readptr = ctlbuf + cp_rem;
+		readsz = CTLBUFSZ - 1 - cp_rem;
+	}
+}
+
+static bool ctl_error (G_GNUC_UNUSED polling_set_t *set, G_GNUC_UNUSED int fd, G_GNUC_UNUSED gpointer user_data)
+{
+	ninfo("Remote writer to control fd closed");
+	return false; /* Don't remove */
+}
 
 int main(int argc, char *argv[])
 {
 	int ret, runtime_status;
 	char cwd[PATH_MAX];
 	char default_pid_file[PATH_MAX];
+	char attach_sock_path[PATH_MAX];
+	char ctl_fifo_path[PATH_MAX];
 	GError *err = NULL;
 	_cleanup_free_ char *contents;
 	int cpid = -1;
 	int status;
 	pid_t pid, create_pid;
-	_cleanup_close_ int logfd = -1;
-	_cleanup_close_ int masterfd_stdout = -1;
-	_cleanup_close_ int masterfd_stderr = -1;
-	_cleanup_close_ int epfd = -1;
 	_cleanup_close_ int csfd = -1;
 	/* Used for !terminal cases. */
 	int slavefd_stdout = -1;
@@ -450,23 +617,17 @@ int main(int argc, char *argv[])
 	char csname[PATH_MAX] = "/tmp/conmon-term.XXXXXXXX";
 	char buf[BUF_SIZE];
 	int num_read;
-	struct epoll_event ev;
-	struct epoll_event evlist[MAX_EVENTS];
+        _cleanup_pollset_ polling_set_t pollset = POLLING_SET_INIT;
 	int sync_pipe_fd = -1;
 	char *sync_pipe, *endptr;
 	int len;
-	int num_stdio_fds = 0;
 	GError *error = NULL;
 	GOptionContext *context;
         GPtrArray *runtime_argv = NULL;
 
-	/* Used for OOM notification API */
-	_cleanup_close_ int efd = -1;
-	_cleanup_close_ int cfd = -1;
-	_cleanup_close_ int ofd = -1;
 	_cleanup_free_ char *memory_cgroup_path = NULL;
 	int wb;
-	uint64_t oom_event;
+
 
 	/* Command line parameters */
 	context = g_option_context_new("- conmon utility");
@@ -743,6 +904,72 @@ int main(int argc, char *argv[])
 	cpid = atoi(contents);
 	ninfo("container PID: %d", cpid);
 
+	/* Setup endpoint for attach */
+	char attach_symlink_dir_path[PATH_MAX];
+	struct sockaddr_un attach_addr = {0};
+	_cleanup_close_ int afd = -1;
+
+	if (!exec) {
+		attach_addr.sun_family = AF_UNIX;
+
+		/*
+		 * Create a symlink so we don't exceed unix domain socket
+		 * path length limit.
+		 */
+		snprintf(attach_symlink_dir_path, PATH_MAX, "/run/%s", cid);
+		if (symlink(bundle_path, attach_symlink_dir_path) == -1)
+			pexit("Failed to create symlink for attach socket");
+
+		snprintf(attach_sock_path, PATH_MAX, "/run/%s/attach", cid);
+		ninfo("attach sock path: %s", attach_sock_path);
+
+		strncpy(attach_addr.sun_path, attach_sock_path, sizeof(attach_addr.sun_path) - 1);
+		ninfo("addr{sun_family=AF_UNIX, sun_path=%s}", attach_addr.sun_path);
+
+		/*
+		 * We make the socket non-blocking to avoid a race where client aborts connection
+		 * before the server gets a chance to call accept. In that scenario, the server
+		 * accept blocks till a new client connection comes in.
+		 */
+		afd = socket(AF_UNIX, SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0);
+		if (afd == -1)
+			pexit("Failed to create attach socket");
+
+                if (fchmod(afd, 0700))
+			pexit("Failed to change attach socket permissions");
+
+		if (bind(afd, (struct sockaddr *)&attach_addr, sizeof(struct sockaddr_un)) == -1)
+			pexit("Failed to bind attach socket: %s", attach_sock_path);
+
+		if (listen(afd, 10) == -1)
+			pexit("Failed to listen on attach socket: %s", attach_sock_path);
+	}
+
+	/* Setup fifo for reading in terminal resize and other stdio control messages */
+	_cleanup_close_ int ctlfd = -1;
+	_cleanup_close_ int dummyfd = -1;
+	if (!exec) {
+		snprintf(ctl_fifo_path, PATH_MAX, "%s/ctl", bundle_path);
+		ninfo("ctl fifo path: %s", ctl_fifo_path);
+
+		if (mkfifo(ctl_fifo_path, 0666) == -1)
+			pexit("Failed to mkfifo at %s", ctl_fifo_path);
+
+		ctlfd = open(ctl_fifo_path, O_RDONLY|O_NONBLOCK|O_CLOEXEC);
+		if (ctlfd == -1)
+			pexit("Failed to open control fifo");
+
+		/*
+		 * Open a dummy writer to prevent getting flood of POLLHUPs when
+		 * last writer closes.
+		 */
+		dummyfd = open(ctl_fifo_path, O_WRONLY|O_CLOEXEC);
+		if (dummyfd == -1)
+			pexit("Failed to open dummy writer for fifo");
+
+		ninfo("ctlfd: %d", ctlfd);
+	}
+
 	/* Send the container pid back to parent */
 	if (sync_pipe_fd > 0 && !exec) {
 		len = snprintf(buf, BUF_SIZE, "{\"pid\": %d}\n", cpid);
@@ -778,83 +1005,43 @@ int main(int argc, char *argv[])
 			pexit("Failed to write to cgroup.event_control");
 	}
 
-	/* Create epoll_ctl so that we can handle read/write events. */
-	/*
-	 * TODO: Switch to libuv so that we can also implement exec as well as
-	 *       attach and other important things. Using epoll directly is just
-	 *       really nasty.
-	 */
-	epfd = epoll_create1(EPOLL_CLOEXEC);
-	if (epfd < 0)
-		pexit("epoll_create");
-	ev.events = EPOLLIN;
+        if (polling_set_init(&pollset) < 0)
+		pexit("polling_set_init");
+        
 	if (masterfd_stdout >= 0) {
-		ev.data.fd = masterfd_stdout;
-		if (epoll_ctl(epfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0)
+		if (polling_set_add_fd(&pollset, masterfd_stdout, stdio_input, stdio_error, GINT_TO_POINTER(STDOUT_PIPE)) < 0)
 			pexit("Failed to add console masterfd_stdout to epoll");
 		num_stdio_fds++;
 	}
 	if (masterfd_stderr >= 0) {
-		ev.data.fd = masterfd_stderr;
-		if (epoll_ctl(epfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0)
-			pexit("Failed to add console masterfd_stderr to epoll");
+		if (polling_set_add_fd(&pollset, masterfd_stderr, stdio_input, stdio_error, GINT_TO_POINTER(STDERR_PIPE)) < 0)
+			pexit("Failed to add console masterfd_stdout to epoll");
 		num_stdio_fds++;
 	}
 
 	/* Add the OOM event fd to epoll */
 	if (oom_handling_enabled) {
-		ev.data.fd = efd;
-		if (epoll_ctl(epfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0)
+		if (polling_set_add_fd(&pollset, efd, oom_input, NULL, NULL) < 0)
 			pexit("Failed to add OOM eventfd to epoll");
 	}
 
+	/* Add the attach socket to epoll */
+	if (afd > 0) {
+		if (polling_set_add_fd(&pollset, afd, attach_input, NULL, NULL) < 0)
+			pexit("Failed to add attach socket fd to epoll");
+	}
+
+	/* Add control fifo fd to epoll */
+	if (ctlfd > 0) {
+		if (polling_set_add_fd(&pollset, ctlfd, ctl_input, ctl_error, NULL) < 0)
+			pexit("Failed to add control fifo fd to epoll");
+	}
+
 	/* Log all of the container's output. */
 	while (num_stdio_fds > 0) {
-		int ready = epoll_wait(epfd, evlist, MAX_EVENTS, -1);
-		if (ready < 0)
-			continue;
-
-		for (int i = 0; i < ready; i++) {
-			if (evlist[i].events & EPOLLIN) {
-				int masterfd = evlist[i].data.fd;
-				stdpipe_t pipe = NO_PIPE;
-				if (masterfd == masterfd_stdout)
-					pipe = STDOUT_PIPE;
-				else if (masterfd == masterfd_stderr)
-					pipe = STDERR_PIPE;
-				else if (oom_handling_enabled && masterfd == efd) {
-					if (read(efd, &oom_event, sizeof(uint64_t)) != sizeof(uint64_t))
-						nwarn("Failed to read event from eventfd");
-					ninfo("OOM received");
-					if (open("oom", O_CREAT, 0666) < 0) {
-						nwarn("Failed to write oom file");
-					}
-				}
-				else {
-					nwarn("unknown pipe fd");
-					goto out;
+		polling_set_iterate(&pollset);
 	}
 
-				if (masterfd == masterfd_stdout || masterfd == masterfd_stderr) {
-					num_read = read(masterfd, buf, BUF_SIZE);
-					if (num_read <= 0)
-						goto out;
-
-					if (write_k8s_log(logfd, pipe, buf, num_read) < 0) {
-						nwarn("write_k8s_log failed");
-						goto out;
-					}
-				}
-			} else if (evlist[i].events & (EPOLLHUP | EPOLLERR)) {
-				printf("closing fd %d\n", evlist[i].data.fd);
-				if (close(evlist[i].data.fd) < 0)
-					pexit("close");
-				num_stdio_fds--;
-			}
-		}
-	}
-
-out:
 	/* Wait for the container process and record its exit code */
 	while ((pid = waitpid(-1, &status, 0)) > 0) {
 		int exit_status = WEXITSTATUS(status);
@@ -904,5 +1091,11 @@ out:
 		}
 	}
 
+	if (!exec) {
+		if (unlink(attach_symlink_dir_path) == -1 && errno != ENOENT) {
+			pexit("Failed to remove symlink");
+		}
+	}
+
 	return EXIT_SUCCESS;
 }

conmon/pollset.c

@@ -0,0 +1,103 @@
+#define _GNU_SOURCE
+
+#include <glib.h>
+#include <sys/epoll.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "pollset.h"
+
+#define MAX_EVENTS 10
+
+typedef struct _polling_fd_t polling_fd_t;
+struct _polling_fd_t {
+	int fd;
+	polling_set_input_cb input_cb;
+	polling_set_error_cb error_cb;
+	gpointer user_data;
+};
+
+static void polling_fd_free(polling_fd_t *polling_fd)
+{
+        if (polling_fd->fd >= 0)
+		close(polling_fd->fd);
+	g_free(polling_fd);
+}
+
+int polling_set_init(polling_set_t *set)
+{
+	set->epfd = epoll_create1(EPOLL_CLOEXEC);
+	if (set->epfd < 0)
+		return -1;
+	set->fd_hash = g_hash_table_new_full(g_direct_hash, g_direct_equal,
+					     NULL, (GDestroyNotify)polling_fd_free);
+	return 0;
+}
+
+void polling_set_destroy(polling_set_t *set)
+{
+	if (set->epfd >= 0)
+		close(set->epfd);
+	if (set->fd_hash)
+		g_hash_table_destroy(set->fd_hash);
+}
+
+int polling_set_add_fd(polling_set_t *set, int fd, polling_set_input_cb input_cb, polling_set_error_cb error_cb, gpointer user_data)
+{
+	struct epoll_event ev;
+	polling_fd_t *polling_fd;
+	
+	ev.events = EPOLLIN;
+	ev.data.fd = fd;
+
+	if (epoll_ctl(set->epfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0)
+		return -1;
+
+	polling_fd = g_new0(polling_fd_t, 1);
+	polling_fd->fd = fd;
+	polling_fd->input_cb = input_cb;
+	polling_fd->error_cb = error_cb;
+	polling_fd->user_data = user_data;
+
+	g_hash_table_insert(set->fd_hash, GINT_TO_POINTER(fd), polling_fd);
+	return 0;
+}
+
+void polling_set_remove_fd(polling_set_t *set, int fd)
+{
+	g_hash_table_remove(set->fd_hash, GINT_TO_POINTER(fd));
+}
+
+int polling_set_iterate(polling_set_t *set)
+{
+	struct epoll_event evlist[MAX_EVENTS];
+	int ready;
+
+	do {
+		ready = epoll_wait(set->epfd, evlist, MAX_EVENTS, -1);
+	} while (ready == -1 && errno == EINTR);
+
+	if (ready < 0)
+		return -1;
+
+	for (int i = 0; i < ready; i++) {
+		int fd = evlist[i].data.fd;
+		polling_fd_t *polling_fd = g_hash_table_lookup(set->fd_hash, GINT_TO_POINTER(fd));
+
+		if (polling_fd == NULL)
+			continue;
+
+		if (evlist[i].events & EPOLLIN &&
+		    polling_fd->input_cb)
+			polling_fd->input_cb(set, fd, polling_fd->user_data);
+		else if (evlist[i].events & (EPOLLHUP | EPOLLERR)) {
+			bool remove = true;
+			if (polling_fd->error_cb)
+				remove = polling_fd->error_cb(set, fd, polling_fd->user_data);
+			if (remove)
+				polling_set_remove_fd(set, fd);
+		}
+  	}
+
+	return 0;
+}

conmon/pollset.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <stdbool.h>
+
+typedef struct _polling_set_t polling_set_t;
+struct _polling_set_t {
+	int epfd;
+	GHashTable *fd_hash;
+};
+
+#define POLLING_SET_INIT { -1, NULL }
+
+typedef void (*polling_set_input_cb) (polling_set_t *set, int fd, gpointer user_data);
+typedef bool (*polling_set_error_cb) (polling_set_t *set, int fd, gpointer user_data);
+
+int polling_set_init(polling_set_t *set);
+void polling_set_destroy(polling_set_t *set);
+int polling_set_add_fd(polling_set_t *set, int fd, polling_set_input_cb input_cb, polling_set_error_cb error_cb, gpointer user_data);
+
+int polling_set_iterate(polling_set_t *set);
+
+#define _cleanup_pollset_ __attribute__((cleanup(polling_set_destroy)))

server/container_attach.go

@@ -1,11 +1,111 @@
 package server
 
 import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/kubernetes-incubator/cri-o/oci"
 	"golang.org/x/net/context"
 	pb "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
+	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
+	"k8s.io/kubernetes/pkg/util/term"
 )
 
 // Attach prepares a streaming endpoint to attach to a running container.
 func (s *Server) Attach(ctx context.Context, req *pb.AttachRequest) (*pb.AttachResponse, error) {
-	return nil, nil
+	logrus.Debugf("AttachRequest %+v", req)
+
+	resp, err := s.GetAttach(req)
+	if err != nil {
+		return nil, fmt.Errorf("unable to prepare attach endpoint")
+	}
+
+	return resp, nil
+}
+
+// Attach endpoint for streaming.Runtime
+func (ss streamService) Attach(containerID string, inputStream io.Reader, outputStream, errorStream io.WriteCloser, tty bool, resize <-chan term.Size) error {
+	c := ss.runtimeServer.GetContainer(containerID)
+
+	if c == nil {
+		return fmt.Errorf("could not find container %q", containerID)
+	}
+
+	if err := ss.runtimeServer.runtime.UpdateStatus(c); err != nil {
+		return err
+	}
+
+	cState := ss.runtimeServer.runtime.ContainerStatus(c)
+	if !(cState.Status == oci.ContainerStateRunning || cState.Status == oci.ContainerStateCreated) {
+		return fmt.Errorf("container is not created or running")
+	}
+
+	controlPath := filepath.Join(c.BundlePath(), "ctl")
+	controlFile, err := os.OpenFile(controlPath, syscall.O_WRONLY, 0)
+	if err != nil {
+		return fmt.Errorf("failed to open container ctl file: %v", err)
+	}
+
+	kubecontainer.HandleResizing(resize, func(size term.Size) {
+		logrus.Infof("Got a resize event: %+v", size)
+		_, err := fmt.Fprintf(controlFile, "%d %d %d\n", 1, size.Height, size.Width)
+		if err != nil {
+			logrus.Infof("Failed to write to control file to resize terminal: %v", err)
+		}
+	})
+
+	attachSocketPath := filepath.Join("/run", c.Name(), "attach")
+	conn, err := net.Dial("unix", attachSocketPath)
+	if err != nil {
+		return fmt.Errorf("failed to connect to container %s attach socket: %v", c.ID(), err)
+	}
+	defer conn.Close()
+
+	receiveStdout := make(chan error)
+	if outputStream != nil || errorStream != nil {
+		go func() {
+			receiveStdout <- redirectResponseToOutputStream(tty, outputStream, errorStream, conn)
+		}()
+	}
+
+	stdinDone := make(chan struct{})
+	go func() {
+		if inputStream != nil {
+			io.Copy(conn, inputStream)
+		}
+		close(stdinDone)
+	}()
+
+	select {
+	case err := <-receiveStdout:
+		return err
+	case <-stdinDone:
+		if outputStream != nil || errorStream != nil {
+			return <-receiveStdout
+		}
+	}
+
+	return nil
+}
+
+func redirectResponseToOutputStream(tty bool, outputStream, errorStream io.Writer, conn io.Reader) error {
+	if outputStream == nil {
+		outputStream = ioutil.Discard
+	}
+	if errorStream == nil {
+		// errorStream = ioutil.Discard
+	}
+	var err error
+	if tty {
+		_, err = io.Copy(outputStream, conn)
+	} else {
+		// TODO
+	}
+	return err
 }