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exp/ssh: Have Wait() return an *ExitError

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I added the clientChan's msg channel to the list of channels that are closed in mainloop when the server sends a channelCloseMsg.

I added an ExitError type that wraps a Waitmsg similar to that of os/exec. I fill ExitStatus with the data returned in the 'exit-status' channel message and Msg with the data returned in the 'exit-signal' channel message.

Instead of having Wait() return on the first 'exit-status'/'exit-signal' I have it return an ExitError containing the status and signal when the clientChan's msg channel is closed.

I added two tests cases to session_test.go that test for exit status 0 (in which case Wait() returns nil) and exit status 1 (in which case Wait() returns an ExitError with ExitStatus 1)

R=dave, agl, rsc, golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5452051
This commit is contained in:
Gustav Paul 2011-12-07 09:58:22 -05:00 committed by Adam Langley
parent 428062da4e
commit 50c24bf6ec
4 changed files with 383 additions and 55 deletions
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38
src/pkg/exp/ssh/client.go
View File

@ -187,10 +187,10 @@ func (c *ClientConn) mainLoop() {
if err != nil {
break
}
// TODO(dfc) A note on blocking channel use.
// The msg, win, data and dataExt channels of a clientChan can
// cause this loop to block indefinately if the consumer does
// not service them.
// TODO(dfc) A note on blocking channel use.
// The msg, win, data and dataExt channels of a clientChan can
// cause this loop to block indefinately if the consumer does
// not service them.
switch packet[0] {
case msgChannelData:
if len(packet) < 9 {
@ -211,7 +211,7 @@ func (c *ClientConn) mainLoop() {
datatype := uint32(packet[5])<<24 | uint32(packet[6])<<16 | uint32(packet[7])<<8 | uint32(packet[8])
if length := int(packet[9])<<24 | int(packet[10])<<16 | int(packet[11])<<8 | int(packet[12]); length > 0 {
packet = packet[13:]
// RFC 4254 5.2 defines data_type_code 1 to be data destined
// RFC 4254 5.2 defines data_type_code 1 to be data destined
// for stderr on interactive sessions. Other data types are
// silently discarded.
if datatype == 1 {
@ -231,9 +231,10 @@ func (c *ClientConn) mainLoop() {
close(ch.stdin.win)
close(ch.stdout.data)
close(ch.stderr.data)
close(ch.msg)
c.chanlist.remove(msg.PeersId)
case *channelEOFMsg:
c.getChan(msg.PeersId).msg <- msg
c.getChan(msg.PeersId).sendEOF()
case *channelRequestSuccessMsg:
c.getChan(msg.PeersId).msg <- msg
case *channelRequestFailureMsg:
@ -249,7 +250,7 @@ func (c *ClientConn) mainLoop() {
}
}
// Dial connects to the given network address using net.Dial and
// Dial connects to the given network address using net.Dial and
// then initiates a SSH handshake, returning the resulting client connection.
func Dial(network, addr string, config *ClientConfig) (*ClientConn, error) {
conn, err := net.Dial(network, addr)
@ -259,18 +260,18 @@ func Dial(network, addr string, config *ClientConfig) (*ClientConn, error) {
return Client(conn, config)
}
// A ClientConfig structure is used to configure a ClientConn. After one has
// A ClientConfig structure is used to configure a ClientConn. After one has
// been passed to an SSH function it must not be modified.
type ClientConfig struct {
// Rand provides the source of entropy for key exchange. If Rand is
// nil, the cryptographic random reader in package crypto/rand will
// Rand provides the source of entropy for key exchange. If Rand is
// nil, the cryptographic random reader in package crypto/rand will
// be used.
Rand io.Reader
// The username to authenticate.
User string
// A slice of ClientAuth methods. Only the first instance
// A slice of ClientAuth methods. Only the first instance
// of a particular RFC 4252 method will be used during authentication.
Auth []ClientAuth
@ -285,7 +286,7 @@ func (c *ClientConfig) rand() io.Reader {
return c.Rand
}
// A clientChan represents a single RFC 4254 channel that is multiplexed
// A clientChan represents a single RFC 4254 channel that is multiplexed
// over a single SSH connection.
type clientChan struct {
packetWriter
@ -297,7 +298,7 @@ type clientChan struct {
}
// newClientChan returns a partially constructed *clientChan
// using the local id provided. To be usable clientChan.peersId
// using the local id provided. To be usable clientChan.peersId
// needs to be assigned once known.
func newClientChan(t *transport, id uint32) *clientChan {
c := &clientChan{
@ -320,8 +321,8 @@ func newClientChan(t *transport, id uint32) *clientChan {
return c
}
// waitForChannelOpenResponse, if successful, fills out
// the peerId and records any initial window advertisement.
// waitForChannelOpenResponse, if successful, fills out
// the peerId and records any initial window advertisement.
func (c *clientChan) waitForChannelOpenResponse() error {
switch msg := (<-c.msg).(type) {
case *channelOpenConfirmMsg:
@ -335,6 +336,13 @@ func (c *clientChan) waitForChannelOpenResponse() error {
return errors.New("unexpected packet")
}
// sendEOF Sends EOF to the server. RFC 4254 Section 5.3
func (c *clientChan) sendEOF() error {
return c.writePacket(marshal(msgChannelEOF, channelEOFMsg{
PeersId: c.peersId,
}))
}
// Close closes the channel. This does not close the underlying connection.
func (c *clientChan) Close() error {
return c.writePacket(marshal(msgChannelClose, channelCloseMsg{

2
src/pkg/exp/ssh/client_func_test.go
View File

@ -6,7 +6,7 @@ package ssh
// ClientConn functional tests.
// These tests require a running ssh server listening on port 22
// on the local host. Functional tests will be skipped unless
// on the local host. Functional tests will be skipped unless
// -ssh.user and -ssh.pass must be passed to gotest.
import (

134
src/pkg/exp/ssh/session.go
View File

@ -34,6 +34,20 @@ const (
SIGUSR2 Signal = "USR2"
)
var signals = map[Signal]int{
SIGABRT: 6,
SIGALRM: 14,
SIGFPE: 8,
SIGHUP: 1,
SIGILL: 4,
SIGINT: 2,
SIGKILL: 9,
SIGPIPE: 13,
SIGQUIT: 3,
SIGSEGV: 11,
SIGTERM: 15,
}
// A Session represents a connection to a remote command or shell.
type Session struct {
// Stdin specifies the remote process's standard input.
@ -170,10 +184,17 @@ func (s *Session) Start(cmd string) error {
return s.start()
}
// Run runs cmd on the remote host and waits for it to terminate.
// Typically, the remote server passes cmd to the shell for
// interpretation. A Session only accepts one call to Run,
// Start or Shell.
// Run runs cmd on the remote host. Typically, the remote
// server passes cmd to the shell for interpretation.
// A Session only accepts one call to Run, Start or Shell.
//
// The returned error is nil if the command runs, has no problems
// copying stdin, stdout, and stderr, and exits with a zero exit
// status.
//
// If the command fails to run or doesn't complete successfully, the
// error is of type *ExitError. Other error types may be
// returned for I/O problems.
func (s *Session) Run(cmd string) error {
err := s.Start(cmd)
if err != nil {
@ -233,6 +254,14 @@ func (s *Session) start() error {
}
// Wait waits for the remote command to exit.
//
// The returned error is nil if the command runs, has no problems
// copying stdin, stdout, and stderr, and exits with a zero exit
// status.
//
// If the command fails to run or doesn't complete successfully, the
// error is of type *ExitError. Other error types may be
// returned for I/O problems.
func (s *Session) Wait() error {
if !s.started {
return errors.New("ssh: session not started")
@ -255,21 +284,40 @@ func (s *Session) Wait() error {
}
func (s *Session) wait() error {
for {
switch msg := (<-s.msg).(type) {
wm := Waitmsg{status: -1}
// Wait for msg channel to be closed before returning.
for msg := range s.msg {
switch msg := msg.(type) {
case *channelRequestMsg:
// TODO(dfc) improve this behavior to match os.Waitmsg
switch msg.Request {
case "exit-status":
d := msg.RequestSpecificData
status := int(d[0])<<24 | int(d[1])<<16 | int(d[2])<<8 | int(d[3])
if status > 0 {
return fmt.Errorf("remote process exited with %d", status)
}
return nil
wm.status = int(d[0])<<24 | int(d[1])<<16 | int(d[2])<<8 | int(d[3])
case "exit-signal":
// TODO(dfc) make a more readable error message
return fmt.Errorf("%v", msg.RequestSpecificData)
signal, rest, ok := parseString(msg.RequestSpecificData)
if !ok {
return fmt.Errorf("wait: could not parse request data: %v", msg.RequestSpecificData)
}
wm.signal = safeString(string(signal))
// skip coreDumped bool
if len(rest) == 0 {
return fmt.Errorf("wait: could not parse request data: %v", msg.RequestSpecificData)
}
rest = rest[1:]
errmsg, rest, ok := parseString(rest)
if !ok {
return fmt.Errorf("wait: could not parse request data: %v", msg.RequestSpecificData)
}
wm.msg = safeString(string(errmsg))
lang, _, ok := parseString(rest)
if !ok {
return fmt.Errorf("wait: could not parse request data: %v", msg.RequestSpecificData)
}
wm.lang = safeString(string(lang))
default:
return fmt.Errorf("wait: unexpected channel request: %v", msg)
}
@ -277,7 +325,20 @@ func (s *Session) wait() error {
return fmt.Errorf("wait: unexpected packet %T received: %v", msg, msg)
}
}
panic("unreachable")
if wm.status == 0 {
return nil
}
if wm.status == -1 {
// exit-status was never sent from server
if wm.signal == "" {
return errors.New("wait: remote command exited without exit status or exit signal")
}
wm.status = 128
if _, ok := signals[Signal(wm.signal)]; ok {
wm.status += signals[Signal(wm.signal)]
}
}
return &ExitError{wm}
}
func (s *Session) stdin() error {
@ -391,3 +452,46 @@ func (c *ClientConn) NewSession() (*Session, error) {
clientChan: ch,
}, nil
}
// An ExitError reports unsuccessful completion of a remote command.
type ExitError struct {
Waitmsg
}
func (e *ExitError) Error() string {
return e.Waitmsg.String()
}
// Waitmsg stores the information about an exited remote command
// as reported by Wait.
type Waitmsg struct {
status int
signal string
msg string
lang string
}
// ExitStatus returns the exit status of the remote command.
func (w Waitmsg) ExitStatus() int {
return w.status
}
// Signal returns the exit signal of the remote command if
// it was terminated violently.
func (w Waitmsg) Signal() string {
return w.signal
}
// Msg returns the exit message given by the remote command
func (w Waitmsg) Msg() string {
return w.msg
}
// Lang returns the language tag. See RFC 3066
func (w Waitmsg) Lang() string {
return w.lang
}
func (w Waitmsg) String() string {
return fmt.Sprintf("Process exited with: %v. Reason was: %v (%v)", w.status, w.msg, w.signal)
}

264
src/pkg/exp/ssh/session_test.go
View File

@ -12,8 +12,10 @@ import (
"testing"
)
type serverType func(*channel)
// dial constructs a new test server and returns a *ClientConn.
func dial(t *testing.T) *ClientConn {
func dial(handler serverType, t *testing.T) *ClientConn {
pw := password("tiger")
serverConfig.PasswordCallback = func(user, pass string) bool {
return user == "testuser" && pass == string(pw)
@ -50,27 +52,7 @@ func dial(t *testing.T) *ClientConn {
continue
}
ch.Accept()
go func() {
defer ch.Close()
// this string is returned to stdout
shell := NewServerShell(ch, "golang")
shell.ReadLine()
type exitMsg struct {
PeersId uint32
Request string
WantReply bool
Status uint32
}
// TODO(dfc) converting to the concrete type should not be
// necessary to send a packet.
msg := exitMsg{
PeersId: ch.(*channel).theirId,
Request: "exit-status",
WantReply: false,
Status: 0,
}
ch.(*channel).serverConn.writePacket(marshal(msgChannelRequest, msg))
}()
go handler(ch.(*channel))
}
t.Log("done")
}()
@ -91,7 +73,7 @@ func dial(t *testing.T) *ClientConn {
// Test a simple string is returned to session.Stdout.
func TestSessionShell(t *testing.T) {
conn := dial(t)
conn := dial(shellHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
@ -116,7 +98,7 @@ func TestSessionShell(t *testing.T) {
// Test a simple string is returned via StdoutPipe.
func TestSessionStdoutPipe(t *testing.T) {
conn := dial(t)
conn := dial(shellHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
@ -147,3 +129,237 @@ func TestSessionStdoutPipe(t *testing.T) {
t.Fatalf("Remote shell did not return expected string: expected=golang, actual=%s", actual)
}
}
// Test non-0 exit status is returned correctly.
func TestExitStatusNonZero(t *testing.T) {
conn := dial(exitStatusNonZeroHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %s", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
err = session.Wait()
if err == nil {
t.Fatalf("expected command to fail but it didn't")
}
e, ok := err.(*ExitError)
if !ok {
t.Fatalf("expected *ExitError but got %T", err)
}
if e.ExitStatus() != 15 {
t.Fatalf("expected command to exit with 15 but got %s", e.ExitStatus())
}
}
// Test 0 exit status is returned correctly.
func TestExitStatusZero(t *testing.T) {
conn := dial(exitStatusZeroHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %s", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
err = session.Wait()
if err != nil {
t.Fatalf("expected nil but got %s", err)
}
}
// Test exit signal and status are both returned correctly.
func TestExitSignalAndStatus(t *testing.T) {
conn := dial(exitSignalAndStatusHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %s", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
err = session.Wait()
if err == nil {
t.Fatalf("expected command to fail but it didn't")
}
e, ok := err.(*ExitError)
if !ok {
t.Fatalf("expected *ExitError but got %T", err)
}
if e.Signal() != "TERM" || e.ExitStatus() != 15 {
t.Fatalf("expected command to exit with signal TERM and status 15 but got signal %s and status %v", e.Signal(), e.ExitStatus())
}
}
// Test exit signal and status are both returned correctly.
func TestKnownExitSignalOnly(t *testing.T) {
conn := dial(exitSignalHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %s", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
err = session.Wait()
if err == nil {
t.Fatalf("expected command to fail but it didn't")
}
e, ok := err.(*ExitError)
if !ok {
t.Fatalf("expected *ExitError but got %T", err)
}
if e.Signal() != "TERM" || e.ExitStatus() != 143 {
t.Fatalf("expected command to exit with signal TERM and status 143 but got signal %s and status %v", e.Signal(), e.ExitStatus())
}
}
// Test exit signal and status are both returned correctly.
func TestUnknownExitSignal(t *testing.T) {
conn := dial(exitSignalUnknownHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %s", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
err = session.Wait()
if err == nil {
t.Fatalf("expected command to fail but it didn't")
}
e, ok := err.(*ExitError)
if !ok {
t.Fatalf("expected *ExitError but got %T", err)
}
if e.Signal() != "SYS" || e.ExitStatus() != 128 {
t.Fatalf("expected command to exit with signal SYS and status 128 but got signal %s and status %v", e.Signal(), e.ExitStatus())
}
}
// Test WaitMsg is not returned if the channel closes abruptly.
func TestExitWithoutStatusOrSignal(t *testing.T) {
conn := dial(exitWithoutSignalOrStatus, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %s", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
err = session.Wait()
if err == nil {
t.Fatalf("expected command to fail but it didn't")
}
_, ok := err.(*ExitError)
if ok {
// you can't actually test for errors.errorString
// because it's not exported.
t.Fatalf("expected *errorString but got %T", err)
}
}
type exitStatusMsg struct {
PeersId uint32
Request string
WantReply bool
Status uint32
}
type exitSignalMsg struct {
PeersId uint32
Request string
WantReply bool
Signal string
CoreDumped bool
Errmsg string
Lang string
}
func exitStatusZeroHandler(ch *channel) {
defer ch.Close()
// this string is returned to stdout
shell := NewServerShell(ch, "> ")
shell.ReadLine()
sendStatus(0, ch)
}
func exitStatusNonZeroHandler(ch *channel) {
defer ch.Close()
shell := NewServerShell(ch, "> ")
shell.ReadLine()
sendStatus(15, ch)
}
func exitSignalAndStatusHandler(ch *channel) {
defer ch.Close()
shell := NewServerShell(ch, "> ")
shell.ReadLine()
sendStatus(15, ch)
sendSignal("TERM", ch)
}
func exitSignalHandler(ch *channel) {
defer ch.Close()
shell := NewServerShell(ch, "> ")
shell.ReadLine()
sendSignal("TERM", ch)
}
func exitSignalUnknownHandler(ch *channel) {
defer ch.Close()
shell := NewServerShell(ch, "> ")
shell.ReadLine()
sendSignal("SYS", ch)
}
func exitWithoutSignalOrStatus(ch *channel) {
defer ch.Close()
shell := NewServerShell(ch, "> ")
shell.ReadLine()
}
func shellHandler(ch *channel) {
defer ch.Close()
// this string is returned to stdout
shell := NewServerShell(ch, "golang")
shell.ReadLine()
sendStatus(0, ch)
}
func sendStatus(status uint32, ch *channel) {
msg := exitStatusMsg{
PeersId: ch.theirId,
Request: "exit-status",
WantReply: false,
Status: status,
}
ch.serverConn.writePacket(marshal(msgChannelRequest, msg))
}
func sendSignal(signal string, ch *channel) {
sig := exitSignalMsg{
PeersId: ch.theirId,
Request: "exit-signal",
WantReply: false,
Signal: signal,
CoreDumped: false,
Errmsg: "Process terminated",
Lang: "en-GB-oed",
}
ch.serverConn.writePacket(marshal(msgChannelRequest, sig))
}