/
ssh_openssh.go
200 lines (179 loc) · 5.28 KB
/
ssh_openssh.go
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// Copyright 2013 Canonical Ltd.
// Licensed under the AGPLv3, see LICENCE file for details.
package ssh
import (
"bytes"
"fmt"
"io"
"os"
"os/exec"
"strings"
"github.com/juju/utils"
)
var opensshCommonOptions = []string{"-o", "StrictHostKeyChecking no"}
// default identities will not be attempted if
// -i is specified and they are not explcitly
// included.
var defaultIdentities = []string{
"~/.ssh/identity",
"~/.ssh/id_rsa",
"~/.ssh/id_dsa",
"~/.ssh/id_ecdsa",
}
type opensshCommandKind int
const (
sshKind opensshCommandKind = iota
scpKind
)
// sshpassWrap wraps the command/args with sshpass if it is found in $PATH
// and the SSHPASS environment variable is set. Otherwise, the original
// command/args are returned.
func sshpassWrap(cmd string, args []string) (string, []string) {
if os.Getenv("SSHPASS") != "" {
if path, err := exec.LookPath("sshpass"); err == nil {
return path, append([]string{"-e", cmd}, args...)
}
}
return cmd, args
}
// OpenSSHClient is an implementation of Client that
// uses the ssh and scp executables found in $PATH.
type OpenSSHClient struct{}
// NewOpenSSHClient creates a new OpenSSHClient.
// If the ssh and scp programs cannot be found
// in $PATH, then an error is returned.
func NewOpenSSHClient() (*OpenSSHClient, error) {
var c OpenSSHClient
if _, err := exec.LookPath("ssh"); err != nil {
return nil, err
}
if _, err := exec.LookPath("scp"); err != nil {
return nil, err
}
return &c, nil
}
func opensshOptions(options *Options, commandKind opensshCommandKind) []string {
args := append([]string{}, opensshCommonOptions...)
if options == nil {
options = &Options{}
}
if len(options.proxyCommand) > 0 {
args = append(args, "-o", "ProxyCommand "+utils.CommandString(options.proxyCommand...))
}
if !options.passwordAuthAllowed {
args = append(args, "-o", "PasswordAuthentication no")
}
// We must set ServerAliveInterval or the server may
// think we've become unresponsive on long running
// command executions such as "apt-get upgrade".
args = append(args, "-o", "ServerAliveInterval 30")
if options.allocatePTY {
args = append(args, "-t", "-t") // twice to force
}
if options.knownHostsFile != "" {
args = append(args, "-o", "UserKnownHostsFile "+utils.CommandString(options.knownHostsFile))
}
identities := append([]string{}, options.identities...)
if pk := PrivateKeyFiles(); len(pk) > 0 {
// Add client keys as implicit identities
identities = append(identities, pk...)
}
// If any identities are specified, the
// default ones must be explicitly specified.
if len(identities) > 0 {
// Restrict SSH to only the explicitly provided identity files.
// Otherwise we may run out of authentication attempts if the
// user has many identity files.
args = append(args, "-o", "IdentitiesOnly yes")
for _, identity := range defaultIdentities {
path, err := utils.NormalizePath(identity)
if err != nil {
logger.Warningf("failed to normalize path %q: %v", identity, err)
continue
}
if _, err := os.Stat(path); err == nil {
identities = append(identities, path)
}
}
}
for _, identity := range identities {
args = append(args, "-i", identity)
}
if options.port != 0 {
port := fmt.Sprint(options.port)
if commandKind == scpKind {
// scp uses -P instead of -p (-p means preserve).
args = append(args, "-P", port)
} else {
args = append(args, "-p", port)
}
}
return args
}
// Command implements Client.Command.
func (c *OpenSSHClient) Command(host string, command []string, options *Options) *Cmd {
args := opensshOptions(options, sshKind)
args = append(args, host)
if len(command) > 0 {
args = append(args, command...)
}
bin, args := sshpassWrap("ssh", args)
logger.Tracef("running: %s %s", bin, utils.CommandString(args...))
return &Cmd{impl: &opensshCmd{exec.Command(bin, args...)}}
}
// Copy implements Client.Copy.
func (c *OpenSSHClient) Copy(args []string, userOptions *Options) error {
var options Options
if userOptions != nil {
options = *userOptions
options.allocatePTY = false // doesn't make sense for scp
}
allArgs := opensshOptions(&options, scpKind)
allArgs = append(allArgs, args...)
bin, allArgs := sshpassWrap("scp", allArgs)
cmd := exec.Command(bin, allArgs...)
var stderr bytes.Buffer
cmd.Stderr = &stderr
logger.Tracef("running: %s %s", bin, utils.CommandString(args...))
if err := cmd.Run(); err != nil {
stderr := strings.TrimSpace(stderr.String())
if len(stderr) > 0 {
err = fmt.Errorf("%v (%v)", err, stderr)
}
return err
}
return nil
}
type opensshCmd struct {
*exec.Cmd
}
func (c *opensshCmd) SetStdio(stdin io.Reader, stdout, stderr io.Writer) {
c.Stdin, c.Stdout, c.Stderr = stdin, stdout, stderr
}
func (c *opensshCmd) StdinPipe() (io.WriteCloser, io.Reader, error) {
wc, err := c.Cmd.StdinPipe()
if err != nil {
return nil, nil, err
}
return wc, c.Stdin, nil
}
func (c *opensshCmd) StdoutPipe() (io.ReadCloser, io.Writer, error) {
rc, err := c.Cmd.StdoutPipe()
if err != nil {
return nil, nil, err
}
return rc, c.Stdout, nil
}
func (c *opensshCmd) StderrPipe() (io.ReadCloser, io.Writer, error) {
rc, err := c.Cmd.StderrPipe()
if err != nil {
return nil, nil, err
}
return rc, c.Stderr, nil
}
func (c *opensshCmd) Kill() error {
if c.Process == nil {
return fmt.Errorf("process has not been started")
}
return c.Process.Kill()
}