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package main
import (
"context"
"fmt"
"math/rand"
"net"
"net/http"
"os"
"os/exec"
"os/signal"
"path/filepath"
"strconv"
"strings"
"syscall"
"time"
"github.com/pkg/browser"
"go.coder.com/flog"
"golang.org/x/xerrors"
)
const codeServerPath = "~/.cache/sshcode/sshcode-server"
const (
sshDirectory = "~/.ssh"
sshDirectoryUnsafeModeMask = 0022
sshControlPath = sshDirectory + "/control-%h-%p-%r"
)
type options struct {
skipSync bool
syncBack bool
noOpen bool
reuseConnection bool
bindAddr string
remotePort string
sshFlags string
}
func sshCode(host, dir string, o options) error {
host, extraSSHFlags, err := parseHost(host)
if err != nil {
return xerrors.Errorf("failed to parse host IP: %w", err)
}
if extraSSHFlags != "" {
o.sshFlags = strings.Join([]string{extraSSHFlags, o.sshFlags}, " ")
}
o.bindAddr, err = parseBindAddr(o.bindAddr)
if err != nil {
return xerrors.Errorf("failed to parse bind address: %w", err)
}
if o.remotePort == "" {
o.remotePort, err = randomPort()
}
if err != nil {
return xerrors.Errorf("failed to find available remote port: %w", err)
}
// Check the SSH directory's permissions and warn the user if it is not safe.
o.reuseConnection = checkSSHDirectory(sshDirectory, o.reuseConnection)
// Start SSH master connection socket. This prevents multiple password prompts from appearing as authentication
// only happens on the initial connection.
if o.reuseConnection {
flog.Info("starting SSH master connection...")
newSSHFlags, cancel, err := startSSHMaster(o.sshFlags, sshControlPath, host)
defer cancel()
if err != nil {
flog.Error("failed to start SSH master connection: %v", err)
o.reuseConnection = false
} else {
o.sshFlags = newSSHFlags
}
}
flog.Info("ensuring code-server is updated...")
dlScript := downloadScript(codeServerPath)
// Downloads the latest code-server and allows it to be executed.
sshCmdStr := fmt.Sprintf("ssh %v %v '/usr/bin/env bash -l'", o.sshFlags, host)
sshCmd := exec.Command("sh", "-l", "-c", sshCmdStr)
sshCmd.Stdout = os.Stdout
sshCmd.Stderr = os.Stderr
sshCmd.Stdin = strings.NewReader(dlScript)
err = sshCmd.Run()
if err != nil {
return xerrors.Errorf("failed to update code-server: \n---ssh cmd---\n%s\n---download script---\n%s: %w",
sshCmdStr,
dlScript,
err,
)
}
if !o.skipSync {
start := time.Now()
flog.Info("syncing settings")
err = syncUserSettings(o.sshFlags, host, false)
if err != nil {
return xerrors.Errorf("failed to sync settings: %w", err)
}
flog.Info("synced settings in %s", time.Since(start))
flog.Info("syncing extensions")
err = syncExtensions(o.sshFlags, host, false)
if err != nil {
return xerrors.Errorf("failed to sync extensions: %w", err)
}
flog.Info("synced extensions in %s", time.Since(start))
}
flog.Info("starting code-server...")
flog.Info("Tunneling remote port %v to %v", o.remotePort, o.bindAddr)
sshCmdStr =
fmt.Sprintf("ssh -tt -q -L %v:localhost:%v %v %v 'cd %v; %v --host 127.0.0.1 --allow-http --no-auth --port=%v'",
o.bindAddr, o.remotePort, o.sshFlags, host, dir, codeServerPath, o.remotePort,
)
// Starts code-server and forwards the remote port.
sshCmd = exec.Command("sh", "-l", "-c", sshCmdStr)
sshCmd.Stdin = os.Stdin
sshCmd.Stdout = os.Stdout
sshCmd.Stderr = os.Stderr
err = sshCmd.Start()
if err != nil {
return xerrors.Errorf("failed to start code-server: %w", err)
}
url := fmt.Sprintf("http://%s", o.bindAddr)
ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
defer cancel()
client := http.Client{
Timeout: time.Second * 3,
}
for {
if ctx.Err() != nil {
return xerrors.Errorf("code-server didn't start in time: %w", ctx.Err())
}
// Waits for code-server to be available before opening the browser.
resp, err := client.Get(url)
if err != nil {
continue
}
resp.Body.Close()
break
}
ctx, cancel = context.WithCancel(context.Background())
if !o.noOpen {
openBrowser(url)
}
go func() {
defer cancel()
sshCmd.Wait()
}()
c := make(chan os.Signal)
signal.Notify(c, os.Interrupt)
select {
case <-ctx.Done():
case <-c:
}
flog.Info("shutting down")
if !o.syncBack || o.skipSync {
return nil
}
flog.Info("synchronizing VS Code back to local")
err = syncExtensions(o.sshFlags, host, true)
if err != nil {
return xerrors.Errorf("failed to sync extensions back: %w", err)
}
err = syncUserSettings(o.sshFlags, host, true)
if err != nil {
return xerrors.Errorf("failed to sync user settings settings back: %w", err)
}
return nil
}
// expandPath returns an expanded version of path.
func expandPath(path string) string {
path = filepath.Clean(os.ExpandEnv(path))
// Replace tilde notation in path with the home directory. You can't replace the first instance of `~` in the
// string with the homedir as having a tilde in the middle of a filename is valid.
homedir := os.Getenv("HOME")
if homedir != "" {
if path == "~" {
path = homedir
} else if strings.HasPrefix(path, "~/") {
path = filepath.Join(homedir, path[2:])
}
}
return filepath.Clean(path)
}
func parseBindAddr(bindAddr string) (string, error) {
if !strings.Contains(bindAddr, ":") {
bindAddr += ":"
}
host, port, err := net.SplitHostPort(bindAddr)
if err != nil {
return "", err
}
if host == "" {
host = "127.0.0.1"
}
if port == "" {
port, err = randomPort()
}
if err != nil {
return "", err
}
return net.JoinHostPort(host, port), nil
}
func openBrowser(url string) {
var openCmd *exec.Cmd
const (
macPath = "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome"
wslPath = "/mnt/c/Program Files (x86)/Google/Chrome/Application/chrome.exe"
)
switch {
case commandExists("google-chrome"):
openCmd = exec.Command("google-chrome", chromeOptions(url)...)
case commandExists("google-chrome-stable"):
openCmd = exec.Command("google-chrome-stable", chromeOptions(url)...)
case commandExists("chromium"):
openCmd = exec.Command("chromium", chromeOptions(url)...)
case commandExists("chromium-browser"):
openCmd = exec.Command("chromium-browser", chromeOptions(url)...)
case pathExists(macPath):
openCmd = exec.Command(macPath, chromeOptions(url)...)
case pathExists(wslPath):
openCmd = exec.Command(wslPath, chromeOptions(url)...)
default:
err := browser.OpenURL(url)
if err != nil {
flog.Error("failed to open browser: %v", err)
}
return
}
// We do not use CombinedOutput because if there is no chrome instance, this will block
// and become the parent process instead of using an existing chrome instance.
err := openCmd.Start()
if err != nil {
flog.Error("failed to open browser: %v", err)
}
}
func chromeOptions(url string) []string {
return []string{"--app=" + url, "--disable-extensions", "--disable-plugins", "--incognito"}
}
// Checks if a command exists locally.
func commandExists(name string) bool {
_, err := exec.LookPath(name)
return err == nil
}
func pathExists(name string) bool {
_, err := os.Stat(name)
return err == nil
}
// randomPort picks a random port to start code-server on.
func randomPort() (string, error) {
const (
minPort = 1024
maxPort = 65535
maxTries = 10
)
for i := 0; i < maxTries; i++ {
port := rand.Intn(maxPort-minPort+1) + minPort
l, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
if err == nil {
_ = l.Close()
return strconv.Itoa(port), nil
}
flog.Info("port taken: %d", port)
}
return "", xerrors.Errorf("max number of tries exceeded: %d", maxTries)
}
// checkSSHDirectory performs sanity and safety checks on sshDirectory, and
// returns a new value for o.reuseConnection depending on the checks.
func checkSSHDirectory(sshDirectory string, reuseConnection bool) bool {
sshDirectoryMode, err := os.Lstat(expandPath(sshDirectory))
if err != nil {
if reuseConnection {
flog.Info("failed to stat %v directory, disabling connection reuse feature: %v", sshDirectory, err)
}
reuseConnection = false
} else {
if !sshDirectoryMode.IsDir() {
if reuseConnection {
flog.Info("%v is not a directory, disabling connection reuse feature", sshDirectory)
} else {
flog.Info("warning: %v is not a directory", sshDirectory)
}
reuseConnection = false
}
if sshDirectoryMode.Mode().Perm()&sshDirectoryUnsafeModeMask != 0 {
flog.Info("warning: the %v directory has unsafe permissions, they should only be writable by "+
"the owner (and files inside should be set to 0600)", sshDirectory)
}
}
return reuseConnection
}
// startSSHMaster starts an SSH master connection and waits for it to be ready.
// It returns a new set of SSH flags for child SSH processes to use.
func startSSHMaster(sshFlags string, sshControlPath string, host string) (string, func(), error) {
ctx, cancel := context.WithCancel(context.Background())
newSSHFlags := fmt.Sprintf(`%v -o "ControlPath=%v"`, sshFlags, sshControlPath)
// -MN means "start a master socket and don't open a session, just connect".
sshCmdStr := fmt.Sprintf(`exec ssh %v -MNq %v`, newSSHFlags, host)
sshMasterCmd := exec.CommandContext(ctx, "sh", "-c", sshCmdStr)
sshMasterCmd.Stdin = os.Stdin
sshMasterCmd.Stderr = os.Stderr
// Gracefully stop the SSH master.
stopSSHMaster := func() {
if sshMasterCmd.Process != nil {
if sshMasterCmd.ProcessState != nil && sshMasterCmd.ProcessState.Exited() {
return
}
err := sshMasterCmd.Process.Signal(syscall.SIGTERM)
if err != nil {
flog.Error("failed to send SIGTERM to SSH master process: %v", err)
}
}
cancel()
}
// Start ssh master and wait. Waiting prevents the process from becoming a zombie process if it dies before
// sshcode does, and allows sshMasterCmd.ProcessState to be populated.
err := sshMasterCmd.Start()
go sshMasterCmd.Wait()
if err != nil {
return "", stopSSHMaster, err
}
err = checkSSHMaster(sshMasterCmd, newSSHFlags, host)
if err != nil {
stopSSHMaster()
return "", stopSSHMaster, xerrors.Errorf("SSH master wasn't ready on time: %w", err)
}
return newSSHFlags, stopSSHMaster, nil
}
// checkSSHMaster polls every second for 30 seconds to check if the SSH master
// is ready.
func checkSSHMaster(sshMasterCmd *exec.Cmd, sshFlags string, host string) error {
var (
maxTries = 30
sleepDur = time.Second
err error
)
for i := 0; i < maxTries; i++ {
// Check if the master is running.
if sshMasterCmd.Process == nil || (sshMasterCmd.ProcessState != nil && sshMasterCmd.ProcessState.Exited()) {
return xerrors.Errorf("SSH master process is not running")
}
// Check if it's ready.
sshCmdStr := fmt.Sprintf(`ssh %v -O check %v`, sshFlags, host)
sshCmd := exec.Command("sh", "-c", sshCmdStr)
err = sshCmd.Run()
if err == nil {
return nil
}
time.Sleep(sleepDur)
}
return xerrors.Errorf("max number of tries exceeded: %d", maxTries)
}
func syncUserSettings(sshFlags string, host string, back bool) error {
localConfDir, err := configDir()
if err != nil {
return err
}
err = ensureDir(localConfDir)
if err != nil {
return err
}
const remoteSettingsDir = "~/.local/share/code-server/User/"
var (
src = localConfDir + "/"
dest = host + ":" + remoteSettingsDir
)
if back {
dest, src = src, dest
}
// Append "/" to have rsync copy the contents of the dir.
return rsync(src, dest, sshFlags, "workspaceStorage", "logs", "CachedData")
}
func syncExtensions(sshFlags string, host string, back bool) error {
localExtensionsDir, err := extensionsDir()
if err != nil {
return err
}
err = ensureDir(localExtensionsDir)
if err != nil {
return err
}
const remoteExtensionsDir = "~/.local/share/code-server/extensions/"
var (
src = localExtensionsDir + "/"
dest = host + ":" + remoteExtensionsDir
)
if back {
dest, src = src, dest
}
return rsync(src, dest, sshFlags)
}
func rsync(src string, dest string, sshFlags string, excludePaths ...string) error {
excludeFlags := make([]string, len(excludePaths))
for i, path := range excludePaths {
excludeFlags[i] = "--exclude=" + path
}
cmd := exec.Command("rsync", append(excludeFlags, "-azvr",
"-e", "ssh "+sshFlags,
// Only update newer directories, and sync times
// to keep things simple.
"-u", "--times",
// This is more unsafe, but it's obnoxious having to enter VS Code
// locally in order to properly delete an extension.
"--delete",
"--copy-unsafe-links",
src, dest,
)...,
)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
err := cmd.Run()
if err != nil {
return xerrors.Errorf("failed to rsync '%s' to '%s': %w", src, dest, err)
}
return nil
}
func downloadScript(codeServerPath string) string {
return fmt.Sprintf(
`set -euxo pipefail || exit 1
[ "$(uname -m)" != "x86_64" ] && echo "Unsupported server architecture $(uname -m). code-server only has releases for x86_64 systems." && exit 1
pkill -f %v || true
mkdir -p ~/.local/share/code-server %v
cd %v
curlflags="-o latest-linux"
if [ -f latest-linux ]; then
curlflags="$curlflags -z latest-linux"
fi
curl $curlflags https://codesrv-ci.cdr.sh/latest-linux
[ -f %v ] && rm %v
ln latest-linux %v
chmod +x %v`,
codeServerPath,
filepath.Dir(codeServerPath),
filepath.Dir(codeServerPath),
codeServerPath,
codeServerPath,
codeServerPath,
codeServerPath,
)
}
// ensureDir creates a directory if it does not exist.
func ensureDir(path string) error {
_, err := os.Stat(path)
if os.IsNotExist(err) {
err = os.MkdirAll(path, 0750)
}
if err != nil {
return err
}
return nil
}
// parseHost parses the host argument. If 'gcp:' is prefixed to the
// host then a lookup is done using gcloud to determine the external IP and any
// additional SSH arguments that should be used for ssh commands. Otherwise, host
// is returned.
func parseHost(host string) (parsedHost string, additionalFlags string, err error) {
host = strings.TrimSpace(host)
switch {
case strings.HasPrefix(host, "gcp:"):
instance := strings.TrimPrefix(host, "gcp:")
return parseGCPSSHCmd(instance)
default:
return host, "", nil
}
}
// parseGCPSSHCmd parses the IP address and flags used by 'gcloud' when
// ssh'ing to an instance.
func parseGCPSSHCmd(instance string) (ip, sshFlags string, err error) {
dryRunCmd := fmt.Sprintf("gcloud compute ssh --dry-run %v", instance)
out, err := exec.Command("sh", "-l", "-c", dryRunCmd).CombinedOutput()
if err != nil {
return "", "", xerrors.Errorf("%s: %w", out, err)
}
toks := strings.Split(string(out), " ")
if len(toks) < 2 {
return "", "", xerrors.Errorf("unexpected output for '%v' command, %s", dryRunCmd, out)
}
// Slice off the '/usr/bin/ssh' prefix and the '<user>@<ip>' suffix.
sshFlags = strings.Join(toks[1:len(toks)-1], " ")
// E.g. foo@1.2.3.4.
userIP := toks[len(toks)-1]
return strings.TrimSpace(userIP), sshFlags, nil
}