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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ssh
// Session tests.
import (
"bytes"
crypto_rand "crypto/rand"
"errors"
"io"
"math/rand"
"net"
"sync"
"testing"
"golang.org/x/crypto/ssh/terminal"
)
type serverType func(Channel, <-chan *Request, *testing.T)
// dial constructs a new test server and returns a *ClientConn.
func dial(handler serverType, t *testing.T) *Client {
c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
var wg sync.WaitGroup
t.Cleanup(wg.Wait)
wg.Add(1)
go func() {
defer func() {
c1.Close()
wg.Done()
}()
conf := ServerConfig{
NoClientAuth: true,
}
conf.AddHostKey(testSigners["rsa"])
conn, chans, reqs, err := NewServerConn(c1, &conf)
if err != nil {
t.Errorf("Unable to handshake: %v", err)
return
}
wg.Add(1)
go func() {
DiscardRequests(reqs)
wg.Done()
}()
for newCh := range chans {
if newCh.ChannelType() != "session" {
newCh.Reject(UnknownChannelType, "unknown channel type")
continue
}
ch, inReqs, err := newCh.Accept()
if err != nil {
t.Errorf("Accept: %v", err)
continue
}
wg.Add(1)
go func() {
handler(ch, inReqs, t)
wg.Done()
}()
}
if err := conn.Wait(); err != io.EOF {
t.Logf("server exit reason: %v", err)
}
}()
config := &ClientConfig{
User: "testuser",
HostKeyCallback: InsecureIgnoreHostKey(),
}
conn, chans, reqs, err := NewClientConn(c2, "", config)
if err != nil {
t.Fatalf("unable to dial remote side: %v", err)
}
return NewClient(conn, chans, reqs)
}
// Test a simple string is returned to session.Stdout.
func TestSessionShell(t *testing.T) {
conn := dial(shellHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %v", err)
}
defer session.Close()
stdout := new(bytes.Buffer)
session.Stdout = stdout
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %s", err)
}
if err := session.Wait(); err != nil {
t.Fatalf("Remote command did not exit cleanly: %v", err)
}
actual := stdout.String()
if actual != "golang" {
t.Fatalf("Remote shell did not return expected string: expected=golang, actual=%s", actual)
}
}
// TODO(dfc) add support for Std{in,err}Pipe when the Server supports it.
// Test a simple string is returned via StdoutPipe.
func TestSessionStdoutPipe(t *testing.T) {
conn := dial(shellHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %v", err)
}
defer session.Close()
stdout, err := session.StdoutPipe()
if err != nil {
t.Fatalf("Unable to request StdoutPipe(): %v", err)
}
var buf bytes.Buffer
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", err)
}
done := make(chan bool, 1)
go func() {
if _, err := io.Copy(&buf, stdout); err != nil {
t.Errorf("Copy of stdout failed: %v", err)
}
done <- true
}()
if err := session.Wait(); err != nil {
t.Fatalf("Remote command did not exit cleanly: %v", err)
}
<-done
actual := buf.String()
if actual != "golang" {
t.Fatalf("Remote shell did not return expected string: expected=golang, actual=%s", actual)
}
}
// Test that a simple string is returned via the Output helper,
// and that stderr is discarded.
func TestSessionOutput(t *testing.T) {
conn := dial(fixedOutputHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %v", err)
}
defer session.Close()
buf, err := session.Output("") // cmd is ignored by fixedOutputHandler
if err != nil {
t.Error("Remote command did not exit cleanly:", err)
}
w := "this-is-stdout."
g := string(buf)
if g != w {
t.Error("Remote command did not return expected string:")
t.Logf("want %q", w)
t.Logf("got %q", g)
}
}
// Test that both stdout and stderr are returned
// via the CombinedOutput helper.
func TestSessionCombinedOutput(t *testing.T) {
conn := dial(fixedOutputHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatalf("Unable to request new session: %v", err)
}
defer session.Close()
buf, err := session.CombinedOutput("") // cmd is ignored by fixedOutputHandler
if err != nil {
t.Error("Remote command did not exit cleanly:", err)
}
const stdout = "this-is-stdout."
const stderr = "this-is-stderr."
g := string(buf)
if g != stdout+stderr && g != stderr+stdout {
t.Error("Remote command did not return expected string:")
t.Logf("want %q, or %q", stdout+stderr, stderr+stdout)
t.Logf("got %q", g)
}
}
// 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: %v", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", 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 %v", 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: %v", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", err)
}
err = session.Wait()
if err != nil {
t.Fatalf("expected nil but got %v", 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: %v", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", 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: %v", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", 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: %v", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", 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())
}
}
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: %v", err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", err)
}
err = session.Wait()
if err == nil {
t.Fatalf("expected command to fail but it didn't")
}
if _, ok := err.(*ExitMissingError); !ok {
t.Fatalf("got %T want *ExitMissingError", err)
}
}
// windowTestBytes is the number of bytes that we'll send to the SSH server.
const windowTestBytes = 16000 * 200
// TestServerWindow writes random data to the server. The server is expected to echo
// the same data back, which is compared against the original.
func TestServerWindow(t *testing.T) {
origBuf := bytes.NewBuffer(make([]byte, 0, windowTestBytes))
io.CopyN(origBuf, crypto_rand.Reader, windowTestBytes)
origBytes := origBuf.Bytes()
conn := dial(echoHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatal(err)
}
defer session.Close()
serverStdin, err := session.StdinPipe()
if err != nil {
t.Fatalf("StdinPipe failed: %v", err)
}
result := make(chan []byte)
go func() {
defer close(result)
echoedBuf := bytes.NewBuffer(make([]byte, 0, windowTestBytes))
serverStdout, err := session.StdoutPipe()
if err != nil {
t.Errorf("StdoutPipe failed: %v", err)
return
}
n, err := copyNRandomly("stdout", echoedBuf, serverStdout, windowTestBytes)
if err != nil && err != io.EOF {
t.Errorf("Read only %d bytes from server, expected %d: %v", n, windowTestBytes, err)
}
result <- echoedBuf.Bytes()
}()
written, err := copyNRandomly("stdin", serverStdin, origBuf, windowTestBytes)
if err != nil {
t.Errorf("failed to copy origBuf to serverStdin: %v", err)
} else if written != windowTestBytes {
t.Errorf("Wrote only %d of %d bytes to server", written, windowTestBytes)
}
echoedBytes := <-result
if !bytes.Equal(origBytes, echoedBytes) {
t.Fatalf("Echoed buffer differed from original, orig %d, echoed %d", len(origBytes), len(echoedBytes))
}
}
// Verify the client can handle a keepalive packet from the server.
func TestClientHandlesKeepalives(t *testing.T) {
conn := dial(channelKeepaliveSender, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatal(err)
}
defer session.Close()
if err := session.Shell(); err != nil {
t.Fatalf("Unable to execute command: %v", err)
}
err = session.Wait()
if err != nil {
t.Fatalf("expected nil but got: %v", err)
}
}
type exitStatusMsg struct {
Status uint32
}
type exitSignalMsg struct {
Signal string
CoreDumped bool
Errmsg string
Lang string
}
func handleTerminalRequests(in <-chan *Request) {
for req := range in {
ok := false
switch req.Type {
case "shell":
ok = true
if len(req.Payload) > 0 {
// We don't accept any commands, only the default shell.
ok = false
}
case "env":
ok = true
}
req.Reply(ok, nil)
}
}
func newServerShell(ch Channel, in <-chan *Request, prompt string) *terminal.Terminal {
term := terminal.NewTerminal(ch, prompt)
go handleTerminalRequests(in)
return term
}
func exitStatusZeroHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
// this string is returned to stdout
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
sendStatus(0, ch, t)
}
func exitStatusNonZeroHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
sendStatus(15, ch, t)
}
func exitSignalAndStatusHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
sendStatus(15, ch, t)
sendSignal("TERM", ch, t)
}
func exitSignalHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
sendSignal("TERM", ch, t)
}
func exitSignalUnknownHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
sendSignal("SYS", ch, t)
}
func exitWithoutSignalOrStatus(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
}
func shellHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
// this string is returned to stdout
shell := newServerShell(ch, in, "golang")
readLine(shell, t)
sendStatus(0, ch, t)
}
// Ignores the command, writes fixed strings to stderr and stdout.
// Strings are "this-is-stdout." and "this-is-stderr.".
func fixedOutputHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
_, err := ch.Read(nil)
req, ok := <-in
if !ok {
t.Fatalf("error: expected channel request, got: %#v", err)
return
}
// ignore request, always send some text
req.Reply(true, nil)
_, err = io.WriteString(ch, "this-is-stdout.")
if err != nil {
t.Fatalf("error writing on server: %v", err)
}
_, err = io.WriteString(ch.Stderr(), "this-is-stderr.")
if err != nil {
t.Fatalf("error writing on server: %v", err)
}
sendStatus(0, ch, t)
}
func readLine(shell *terminal.Terminal, t *testing.T) {
if _, err := shell.ReadLine(); err != nil && err != io.EOF {
t.Errorf("unable to read line: %v", err)
}
}
func sendStatus(status uint32, ch Channel, t *testing.T) {
msg := exitStatusMsg{
Status: status,
}
if _, err := ch.SendRequest("exit-status", false, Marshal(&msg)); err != nil {
t.Errorf("unable to send status: %v", err)
}
}
func sendSignal(signal string, ch Channel, t *testing.T) {
sig := exitSignalMsg{
Signal: signal,
CoreDumped: false,
Errmsg: "Process terminated",
Lang: "en-GB-oed",
}
if _, err := ch.SendRequest("exit-signal", false, Marshal(&sig)); err != nil {
t.Errorf("unable to send signal: %v", err)
}
}
func discardHandler(ch Channel, t *testing.T) {
defer ch.Close()
io.Copy(io.Discard, ch)
}
func echoHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
if n, err := copyNRandomly("echohandler", ch, ch, windowTestBytes); err != nil {
t.Errorf("short write, wrote %d, expected %d: %v ", n, windowTestBytes, err)
}
}
// copyNRandomly copies n bytes from src to dst. It uses a variable, and random,
// buffer size to exercise more code paths.
func copyNRandomly(title string, dst io.Writer, src io.Reader, n int) (int, error) {
var (
buf = make([]byte, 32*1024)
written int
remaining = n
)
for remaining > 0 {
l := rand.Intn(1 << 15)
if remaining < l {
l = remaining
}
nr, er := src.Read(buf[:l])
nw, ew := dst.Write(buf[:nr])
remaining -= nw
written += nw
if ew != nil {
return written, ew
}
if nr != nw {
return written, io.ErrShortWrite
}
if er != nil && er != io.EOF {
return written, er
}
}
return written, nil
}
func channelKeepaliveSender(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
shell := newServerShell(ch, in, "> ")
readLine(shell, t)
if _, err := ch.SendRequest("keepalive@openssh.com", true, nil); err != nil {
t.Errorf("unable to send channel keepalive request: %v", err)
}
sendStatus(0, ch, t)
}
func TestClientWriteEOF(t *testing.T) {
conn := dial(simpleEchoHandler, t)
defer conn.Close()
session, err := conn.NewSession()
if err != nil {
t.Fatal(err)
}
defer session.Close()
stdin, err := session.StdinPipe()
if err != nil {
t.Fatalf("StdinPipe failed: %v", err)
}
stdout, err := session.StdoutPipe()
if err != nil {
t.Fatalf("StdoutPipe failed: %v", err)
}
data := []byte(`0000`)
_, err = stdin.Write(data)
if err != nil {
t.Fatalf("Write failed: %v", err)
}
stdin.Close()
res, err := io.ReadAll(stdout)
if err != nil {
t.Fatalf("Read failed: %v", err)
}
if !bytes.Equal(data, res) {
t.Fatalf("Read differed from write, wrote: %v, read: %v", data, res)
}
}
func simpleEchoHandler(ch Channel, in <-chan *Request, t *testing.T) {
defer ch.Close()
data, err := io.ReadAll(ch)
if err != nil {
t.Errorf("handler read error: %v", err)
}
_, err = ch.Write(data)
if err != nil {
t.Errorf("handler write error: %v", err)
}
}
func TestSessionID(t *testing.T) {
c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
defer c1.Close()
defer c2.Close()
serverID := make(chan []byte, 1)
clientID := make(chan []byte, 1)
serverConf := &ServerConfig{
NoClientAuth: true,
}
serverConf.AddHostKey(testSigners["ecdsa"])
clientConf := &ClientConfig{
HostKeyCallback: InsecureIgnoreHostKey(),
User: "user",
}
var wg sync.WaitGroup
t.Cleanup(wg.Wait)
srvErrCh := make(chan error, 1)
wg.Add(1)
go func() {
defer wg.Done()
conn, chans, reqs, err := NewServerConn(c1, serverConf)
srvErrCh <- err
if err != nil {
return
}
serverID <- conn.SessionID()
wg.Add(1)
go func() {
DiscardRequests(reqs)
wg.Done()
}()
for ch := range chans {
ch.Reject(Prohibited, "")
}
}()
cliErrCh := make(chan error, 1)
wg.Add(1)
go func() {
defer wg.Done()
conn, chans, reqs, err := NewClientConn(c2, "", clientConf)
cliErrCh <- err
if err != nil {
return
}
clientID <- conn.SessionID()
wg.Add(1)
go func() {
DiscardRequests(reqs)
wg.Done()
}()
for ch := range chans {
ch.Reject(Prohibited, "")
}
}()
if err := <-srvErrCh; err != nil {
t.Fatalf("server handshake: %v", err)
}
if err := <-cliErrCh; err != nil {
t.Fatalf("client handshake: %v", err)
}
s := <-serverID
c := <-clientID
if bytes.Compare(s, c) != 0 {
t.Errorf("server session ID (%x) != client session ID (%x)", s, c)
} else if len(s) == 0 {
t.Errorf("client and server SessionID were empty.")
}
}
type noReadConn struct {
readSeen bool
net.Conn
}
func (c *noReadConn) Close() error {
return nil
}
func (c *noReadConn) Read(b []byte) (int, error) {
c.readSeen = true
return 0, errors.New("noReadConn error")
}
func TestInvalidServerConfiguration(t *testing.T) {
c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
defer c1.Close()
defer c2.Close()
serveConn := noReadConn{Conn: c1}
serverConf := &ServerConfig{}
NewServerConn(&serveConn, serverConf)
if serveConn.readSeen {
t.Fatalf("NewServerConn attempted to Read() from Conn while configuration is missing host key")
}
serverConf.AddHostKey(testSigners["ecdsa"])
NewServerConn(&serveConn, serverConf)
if serveConn.readSeen {
t.Fatalf("NewServerConn attempted to Read() from Conn while configuration is missing authentication method")
}
}
func TestHostKeyAlgorithms(t *testing.T) {
serverConf := &ServerConfig{
NoClientAuth: true,
}
serverConf.AddHostKey(testSigners["rsa"])
serverConf.AddHostKey(testSigners["ecdsa"])
var wg sync.WaitGroup
t.Cleanup(wg.Wait)
connect := func(clientConf *ClientConfig, want string) {
var alg string
clientConf.HostKeyCallback = func(h string, a net.Addr, key PublicKey) error {
alg = key.Type()
return nil
}
c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
defer c1.Close()
defer c2.Close()
wg.Add(1)
go func() {
NewServerConn(c1, serverConf)
wg.Done()
}()
_, _, _, err = NewClientConn(c2, "", clientConf)
if err != nil {
t.Fatalf("NewClientConn: %v", err)
}
if alg != want {
t.Errorf("selected key algorithm %s, want %s", alg, want)
}
}
// By default, we get the preferred algorithm, which is ECDSA 256.
clientConf := &ClientConfig{
HostKeyCallback: InsecureIgnoreHostKey(),
}
connect(clientConf, KeyAlgoECDSA256)
// Client asks for RSA explicitly.
clientConf.HostKeyAlgorithms = []string{KeyAlgoRSA}
connect(clientConf, KeyAlgoRSA)
// Client asks for RSA-SHA2-512 explicitly.
clientConf.HostKeyAlgorithms = []string{KeyAlgoRSASHA512}
// We get back an "ssh-rsa" key but the verification happened
// with an RSA-SHA2-512 signature.
connect(clientConf, KeyAlgoRSA)
c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
defer c1.Close()
defer c2.Close()
wg.Add(1)
go func() {
NewServerConn(c1, serverConf)
wg.Done()
}()
clientConf.HostKeyAlgorithms = []string{"nonexistent-hostkey-algo"}
_, _, _, err = NewClientConn(c2, "", clientConf)
if err == nil {
t.Fatal("succeeded connecting with unknown hostkey algorithm")
}
}
func TestServerClientAuthCallback(t *testing.T) {
c1, c2, err := netPipe()
if err != nil {
t.Fatalf("netPipe: %v", err)
}
defer c1.Close()
defer c2.Close()
userCh := make(chan string, 1)
serverConf := &ServerConfig{
NoClientAuth: true,
NoClientAuthCallback: func(conn ConnMetadata) (*Permissions, error) {
userCh <- conn.User()
return nil, nil
},
}
const someUsername = "some-username"
serverConf.AddHostKey(testSigners["ecdsa"])
clientConf := &ClientConfig{
HostKeyCallback: InsecureIgnoreHostKey(),
User: someUsername,
}
var wg sync.WaitGroup
t.Cleanup(wg.Wait)
wg.Add(1)
go func() {
defer wg.Done()
_, chans, reqs, err := NewServerConn(c1, serverConf)
if err != nil {
t.Errorf("server handshake: %v", err)
userCh <- "error"
return
}
wg.Add(1)
go func() {
DiscardRequests(reqs)
wg.Done()
}()
for ch := range chans {
ch.Reject(Prohibited, "")
}
}()
conn, _, _, err := NewClientConn(c2, "", clientConf)
if err != nil {
t.Fatalf("client handshake: %v", err)
return
}
conn.Close()
got := <-userCh
if got != someUsername {
t.Errorf("username = %q; want %q", got, someUsername)
}
}