/
session.go
421 lines (373 loc) · 9.41 KB
/
session.go
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package ssh
import (
"bytes"
"fmt"
"github.com/lunixbochs/vtclean"
"github.com/pkg/errors"
"github.com/viant/toolbox"
"golang.org/x/crypto/ssh"
"io"
"strings"
"sync/atomic"
"time"
"sync"
)
//ErrTerminated - command session terminated
var ErrTerminated = errors.New("terminate")
const defaultShell = "/bin/bash"
const (
drainTimeoutMs = 10
defaultTimeoutMs = 5000
initTimeoutMs = 200
defaultTickFrequency = 100
)
//Listener represent command listener (it will send stdout fragments as thier being available on stdout)
type Listener func(stdout string, hasMore bool)
//MultiCommandSession represents a multi command session
type MultiCommandSession interface {
Run(command string, listener Listener, timeoutMs int, terminators ...string) (string, error)
ShellPrompt() string
System() string
Reconnect() error
Close()
}
//multiCommandSession represents a multi command session
//a new command are send vi stdin
type multiCommandSession struct {
service *service
config *SessionConfig
replayCommands *ReplayCommands
recordSession bool
session *ssh.Session
stdOutput chan string
stdError chan string
stdInput io.WriteCloser
promptSequence string
shellPrompt string
escapedShellPrompt string
system string
running int32
}
func (s *multiCommandSession) Run(command string, listener Listener, timeoutMs int, terminators ...string) (string, error) {
if atomic.LoadInt32(&s.running) == 0 {
return "", ErrTerminated
}
s.drainStdout()
var stdin = command + "\n"
_, err := s.stdInput.Write([]byte(stdin))
if err != nil {
return "", fmt.Errorf("failed to execute command: %v, err: %v", command, err)
}
var output string
output, _, err = s.readResponse(timeoutMs, listener, terminators...)
if s.recordSession {
s.replayCommands.Register(stdin, output)
}
return output, err
}
//ShellPrompt returns a shell prompt
func (s *multiCommandSession) ShellPrompt() string {
return s.shellPrompt
}
//System returns a system name
func (s *multiCommandSession) System() string {
return s.system
}
//Close closes the session with its resources
func (s *multiCommandSession) Close() {
atomic.StoreInt32(&s.running, 0)
s.stdInput.Close()
if s.session != nil {
s.session.Close()
}
}
func (s *multiCommandSession) closeIfError(err error) bool {
if err != nil {
s.Close()
return true
}
return false
}
func (s *multiCommandSession) start(shell string) (output string, err error) {
var reader, errReader io.Reader
reader, err = s.session.StdoutPipe()
if err != nil {
return "", err
}
errReader, err = s.session.StderrPipe()
if err != nil {
return "", err
}
waitGroup := sync.WaitGroup{}
waitGroup.Add(2)
go func(){
waitGroup.Done()
s.copy(reader, s.stdOutput)
}()
go func() {
waitGroup.Done()
s.copy(errReader, s.stdError)
}()
if shell == "" {
shell = defaultShell
}
waitGroup.Wait()
err = s.session.Start(shell)
if err != nil {
return "", err
}
output, _, err = s.readResponse(drainTimeoutMs, nil)
return output, err
}
//copy copy data from reader to channel
func (s *multiCommandSession) copy(reader io.Reader, out chan string) {
var written int64 = 0
buf := make([]byte, 128*1024)
var err error
var bytesRead int
for {
writer := new(bytes.Buffer)
if atomic.LoadInt32(&s.running) == 0 {
return
}
bytesRead, err = reader.Read(buf)
if bytesRead > 0 {
bytesWritten, writeError := writer.Write(buf[:bytesRead])
if s.closeIfError(writeError) {
return
}
if bytesWritten > 0 {
written += int64(bytesWritten)
}
if bytesRead != bytesWritten {
if s.closeIfError(io.ErrShortWrite) {
return
}
}
out <- string(writer.Bytes())
}
if s.closeIfError(err) {
return
}
}
}
func escapeInput(input string) string {
input = vtclean.Clean(input, false)
if input == "" {
return input
}
return strings.Trim(input, "\n\r\t ")
}
func (s *multiCommandSession) Reconnect() (err error) {
atomic.StoreInt32(&s.running, 1)
s.service.Reconnect()
s.session, err = s.service.client.NewSession()
defer func() {
if err != nil {
s.service.client.Close()
}
}()
if err != nil {
return err
}
return s.init()
}
func (s *multiCommandSession) hasPrompt(input string) bool {
escapedInput := escapeInput(input)
var shellPrompt = s.shellPrompt
if shellPrompt == "" {
shellPrompt = "$"
}
if s.escapedShellPrompt == "" && s.shellPrompt != "" {
s.escapedShellPrompt = escapeInput(s.shellPrompt)
}
if s.escapedShellPrompt != "" && strings.HasSuffix(escapedInput, s.escapedShellPrompt) || strings.HasSuffix(input, s.shellPrompt) {
return true
}
return false
}
func (s *multiCommandSession) hasTerminator(input string, terminators ...string) bool {
escapedInput := escapeInput(input)
input = escapedInput
for _, candidate := range terminators {
candidateLen := len(candidate)
if candidateLen == 0 {
continue
}
if candidate[0:1] == "^" && strings.HasPrefix(input, candidate[1:]) {
return true
}
if candidate[candidateLen-1:] == "$" && strings.HasSuffix(input, candidate[:candidateLen-1]) {
return true
}
if strings.Contains(input, candidate) {
return true
}
}
return false
}
func (s *multiCommandSession) removePromptIfNeeded(stdout string) string {
if strings.Contains(stdout, s.shellPrompt) {
stdout = strings.Replace(stdout, s.shellPrompt, "", 1)
stdout = strings.Replace(stdout, "\r", "", len(stdout))
var lines = []string{}
for _, line := range strings.Split(stdout, "\n") {
if strings.TrimSpace(line) == "" {
continue
}
lines = append(lines, line)
}
stdout = strings.Join(lines, "\r\n")
}
return stdout
}
func (s *multiCommandSession) readResponse(timeoutMs int, listener Listener, terminators ...string) (out string, has bool, err error) {
if timeoutMs == 0 {
timeoutMs = defaultTimeoutMs
}
defer func() {
if listener != nil {
listener("", false)
}
}()
var done int32
defer atomic.StoreInt32(&done, 1)
var errOut string
var hasOutput bool
var waitTimeMs = 0
var tickFrequencyMs = defaultTickFrequency
if tickFrequencyMs > timeoutMs {
tickFrequencyMs = timeoutMs
}
var timeoutDuration = time.Duration(tickFrequencyMs) * time.Millisecond
var hasPrompt, hasTerminator bool
outer:
for {
select {
case o := <-s.stdOutput:
if len(o) > 0 {
waitTimeMs = 0
if listener != nil {
listener(s.removePromptIfNeeded(o), true)
}
}
out += o
hasPrompt = s.hasPrompt(out)
hasTerminator = s.hasTerminator(out, terminators...)
if (hasPrompt || hasTerminator) && len(s.stdOutput) == 0 {
break outer
}
case e := <-s.stdError:
errOut += e
if listener != nil {
listener(s.removePromptIfNeeded(e), true)
}
hasPrompt = s.hasPrompt(errOut)
hasTerminator = s.hasTerminator(errOut, terminators...)
if (hasPrompt || hasTerminator) && len(s.stdOutput) == 0 {
break outer
}
case <-time.After(timeoutDuration):
waitTimeMs += tickFrequencyMs
if waitTimeMs >= timeoutMs {
break outer
}
}
}
if hasTerminator {
s.drainStdout()
}
if errOut != "" {
err = errors.New(errOut)
}
if len(out) > 0 {
hasOutput = true
out = s.removePromptIfNeeded(out)
}
return out, hasOutput, err
}
func (s *multiCommandSession) drainStdout() {
//read any outstanding output
for {
_, has, _ := s.readResponse(drainTimeoutMs, nil, "")
if !has {
return
}
}
}
func (s *multiCommandSession) shellInit() (err error) {
if s.promptSequence != "" {
if _, err = s.Run(s.promptSequence, nil, initTimeoutMs); err != nil {
return err
}
}
var ts = toolbox.AsString(time.Now().UnixNano())
s.promptSequence = "PS1=\"\\h:\\u" + ts + "\\$\""
s.shellPrompt = ""
s.escapedShellPrompt = ""
for i := 1; i < 10; i++ { //for slow connection, make sure that you have right promot
s.shellPrompt, err = s.Run(s.promptSequence, nil, i * initTimeoutMs)
if err != nil {
return err
}
if strings.Contains(s.shellPrompt, ts+"$") {
break
}
}
if !strings.Contains(s.shellPrompt, ts+"$") {
s.shellPrompt = ts + "$"
}
if s.closeIfError(err) {
return err
}
s.escapedShellPrompt = escapeInput(s.shellPrompt)
s.system, err = s.Run("uname -s", nil, defaultTimeoutMs)
s.system = strings.ToLower(s.system)
return nil
}
func (s *multiCommandSession) init() (err error) {
s.session, err = s.service.client.NewSession()
defer func() {
if err != nil {
s.service.client.Close()
}
}()
s.stdOutput = make(chan string)
s.stdError = make(chan string)
for k, v := range s.config.EnvVariables {
err = s.session.Setenv(k, v)
if err != nil {
return err
}
}
modes := ssh.TerminalModes{
ssh.ECHO: 0, // disable echoing
ssh.TTY_OP_ISPEED: 14400, // input speed = 14.4kbaud
ssh.TTY_OP_OSPEED: 14400, // output speed = 14.4kbaud
}
if err := s.session.RequestPty(s.config.Term, s.config.Rows, s.config.Columns, modes); err != nil {
return err
}
if s.stdInput, err = s.session.StdinPipe(); err != nil {
return err
}
_, err = s.start(s.config.Shell)
if s.closeIfError(err) {
return err
}
return s.shellInit()
}
func newMultiCommandSession(service *service, config *SessionConfig, replayCommands *ReplayCommands, recordSession bool) (MultiCommandSession, error) {
if config == nil {
config = &SessionConfig{}
}
config.applyDefault()
result := &multiCommandSession{
service: service,
config: config,
running: 1,
recordSession: recordSession,
replayCommands: replayCommands,
}
return result, result.init()
}