1979486890

Committed 12 Aug 2025 09:38AM UTC coverage: 76.223% (-0.02%) from 76.243%

Build # 1979486890

Build Type

push

gitlab-ci

Committed by

web-flow

Commit Message

Merge pull request #727 from michalkopczan/MEN-8429_mender-artifact-waits-indefinitely-if-ssh-connection-fails-silently

fix: mender-artifact hangs when ssh connection fails silently

Run Details

0 of 2 new or added lines in 1 file covered. (0.0%)

2 existing lines in 1 file now uncovered.

5982 of 7848 relevant lines covered (76.22%)

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/cli/util/ssh.go

// Copyright 2025 Northern.tech AS
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.

package util

import (
        "bufio"
        "context"
        "io"
        "os"
        "os/exec"
        "os/signal"
        "strings"
        "syscall"
        "time"

        "github.com/pkg/errors"
        "github.com/urfave/cli"
)

type SSHCommand struct {
        Cmd     *exec.Cmd
        ctx     context.Context
        Stdout  io.ReadCloser
        cancel  context.CancelFunc
        sigChan chan os.Signal
        errChan chan error
}

func StartSSHCommand(c *cli.Context,
        _ctx context.Context,
        cancel context.CancelFunc,
        command string,
        sshConnectedToken string,
) (*SSHCommand, error) {

        var userAtHost string
        var sigChan chan os.Signal
        var errChan chan error
        port := "22"
        host := strings.TrimPrefix(c.String("file"), "ssh://")

        if remotePort := strings.Split(host, ":"); len(remotePort) == 2 {
                port = remotePort[1]
                userAtHost = remotePort[0]
        } else {
                userAtHost = host
        }

        args := c.StringSlice("ssh-args")
        // Check if port is specified explicitly with the --ssh-args flag
        addPort := true
        for _, arg := range args {
                if strings.Contains(arg, "-p") {
                        addPort = false
                        break
                }
        }
        if addPort {
                args = append(args, "-p", port)
        }
        args = append(args, userAtHost)
        args = append(
                args,
                "-o ServerAliveInterval=30",
                "-o ServerAliveCountMax=1",
                "/bin/sh",
                "-c",
                command)

        cmd := exec.Command("ssh", args...)

        // Simply connect stdin/stderr
        cmd.Stdin = os.Stdin
        cmd.Stderr = os.Stderr
        stdout, err := cmd.StdoutPipe()
        if err != nil {
                return nil, errors.New("Error redirecting stdout on exec")
        }

        // Disable tty echo before starting
        term, err := DisableEcho(int(os.Stdin.Fd()))
        if err == nil {
                sigChan = make(chan os.Signal, 1)
                errChan = make(chan error, 1)
                // Make sure that echo is enabled if the process gets
                // interrupted
                signal.Notify(sigChan)
                go EchoSigHandler(_ctx, sigChan, errChan, term)
        } else if err != syscall.ENOTTY {
                return nil, err
        }

        if err := cmd.Start(); err != nil {
                return nil, err
        }

        // Wait for 120 seconds for ssh to establish connection
        err = waitForBufferSignal(stdout, os.Stdout, sshConnectedToken, 2*time.Minute)
        if err != nil {
                _ = cmd.Process.Kill()
                return nil, errors.Wrap(err,
                        "Error waiting for ssh session to be established.")
        }
        return &SSHCommand{
                ctx:     _ctx,
                Cmd:     cmd,
                Stdout:  stdout,
                cancel:  cancel,
                sigChan: sigChan,
                errChan: errChan,
        }, nil
}

func (s *SSHCommand) EndSSHCommand() error {
        if s.Cmd.ProcessState != nil && s.Cmd.ProcessState.Exited() {
                return errors.New("SSH session closed unexpectedly")
        }

        if err := s.Cmd.Wait(); err != nil {
                return errors.Wrap(err,
                        "SSH session closed with error")
        }

        if s.sigChan != nil {
                signal.Stop(s.sigChan)
                s.cancel()
                if err := <-s.errChan; err != nil {
                        return err
                }
        } else {
                s.cancel()
        }

        return nil
}

// Reads from src waiting for the string specified by signal, writing all other
// output appearing at src to sink. The function returns an error if occurs
// reading from the stream or the deadline exceeds.
func waitForBufferSignal(src io.Reader, sink io.Writer,
        signal string, deadline time.Duration) error {

        var err error
        errChan := make(chan error)

        go func() {
                stdoutRdr := bufio.NewReader(src)
                for {
                        line, err := stdoutRdr.ReadString('\n')
                        if err != nil {
                                errChan <- err
                                break
                        }
                        if strings.Contains(line, signal) {
                                errChan <- nil
                                break
                        }
                        _, err = sink.Write([]byte(line + "\n"))
                        if err != nil {
                                errChan <- err
                                break
                        }
                }
        }()

        select {
        case err = <-errChan:
                // Error from goroutine
        case <-time.After(deadline):
                err = errors.New("Input deadline exceeded")
        }
        return err
}

1	// Copyright 2025 Northern.tech AS
2	//
3	// Licensed under the Apache License, Version 2.0 (the "License");
4	// you may not use this file except in compliance with the License.
5	// You may obtain a copy of the License at
6	//
7	// http://www.apache.org/licenses/LICENSE-2.0
8	//
9	// Unless required by applicable law or agreed to in writing, software
10	// distributed under the License is distributed on an "AS IS" BASIS,
11	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12	// See the License for the specific language governing permissions and
13	// limitations under the License.
14
15	package util
16
17	import (
18	"bufio"
19	"context"
20	"io"
21	"os"
22	"os/exec"
23	"os/signal"
24	"strings"
25	"syscall"
26	"time"
27
28	"github.com/pkg/errors"
29	"github.com/urfave/cli"
30	)
31
32	type SSHCommand struct {
33	Cmd *exec.Cmd
34	ctx context.Context
35	Stdout io.ReadCloser
36	cancel context.CancelFunc
37	sigChan chan os.Signal
38	errChan chan error
39	}
40
41	func StartSSHCommand(c *cli.Context,
42	_ctx context.Context,
43	cancel context.CancelFunc,
44	command string,
45	sshConnectedToken string,
46	) (*SSHCommand, error) {	×
47		×
48	var userAtHost string	×
49	var sigChan chan os.Signal	×
50	var errChan chan error	×
51	port := "22"	×
52	host := strings.TrimPrefix(c.String("file"), "ssh://")	×
53		×
54	if remotePort := strings.Split(host, ":"); len(remotePort) == 2 {	×
55	port = remotePort[1]	×
56	userAtHost = remotePort[0]	×
57	} else {	×
58	userAtHost = host	×
59	}	×
60
61	args := c.StringSlice("ssh-args")	×
62	// Check if port is specified explicitly with the --ssh-args flag	×
63	addPort := true	×
64	for _, arg := range args {	×
65	if strings.Contains(arg, "-p") {	×
66	addPort = false	×
67	break	×
68	}
69	}
70	if addPort {	×
71	args = append(args, "-p", port)	×
72	}	×
73	args = append(args, userAtHost)	×
74	args = append(	×
75	args,	×
NEW 76	"-o ServerAliveInterval=30",	×
NEW 77	"-o ServerAliveCountMax=1",	×
78	"/bin/sh",	×
79	"-c",	×
80	command)	×
81		×
82	cmd := exec.Command("ssh", args...)	×
83		×
84	// Simply connect stdin/stderr	×
85	cmd.Stdin = os.Stdin	×
86	cmd.Stderr = os.Stderr	×
87	stdout, err := cmd.StdoutPipe()	×
88	if err != nil {	×
89	return nil, errors.New("Error redirecting stdout on exec")	×
90	}	×
91
92	// Disable tty echo before starting
93	term, err := DisableEcho(int(os.Stdin.Fd()))	×
94	if err == nil {	×
95	sigChan = make(chan os.Signal, 1)	×
96	errChan = make(chan error, 1)	×
97	// Make sure that echo is enabled if the process gets	×
98	// interrupted	×
99	signal.Notify(sigChan)	×
100	go EchoSigHandler(_ctx, sigChan, errChan, term)	×
101	} else if err != syscall.ENOTTY {	×
102	return nil, err	×
103	}	×
104
105	if err := cmd.Start(); err != nil {	×
106	return nil, err	×
107	}	×
108
109	// Wait for 120 seconds for ssh to establish connection
110	err = waitForBufferSignal(stdout, os.Stdout, sshConnectedToken, 2*time.Minute)	×
111	if err != nil {	×
112	_ = cmd.Process.Kill()	×
113	return nil, errors.Wrap(err,	×
114	"Error waiting for ssh session to be established.")	×
115	}	×
116	return &SSHCommand{	×
117	ctx: _ctx,	×
118	Cmd: cmd,	×
119	Stdout: stdout,	×
120	cancel: cancel,	×
121	sigChan: sigChan,	×
122	errChan: errChan,	×
123	}, nil	×
124	}
125
126	func (s *SSHCommand) EndSSHCommand() error {	×
127	if s.Cmd.ProcessState != nil && s.Cmd.ProcessState.Exited() {	×
128	return errors.New("SSH session closed unexpectedly")	×
129	}	×
130
131	if err := s.Cmd.Wait(); err != nil {	×
132	return errors.Wrap(err,	×
133	"SSH session closed with error")	×
134	}	×
135
136	if s.sigChan != nil {	×
137	signal.Stop(s.sigChan)	×
138	s.cancel()	×
139	if err := <-s.errChan; err != nil {	×
140	return err	×
141	}	×
142	} else {	×
143	s.cancel()	×
144	}	×
145
146	return nil	×
147	}
148
149	// Reads from src waiting for the string specified by signal, writing all other
150	// output appearing at src to sink. The function returns an error if occurs
151	// reading from the stream or the deadline exceeds.
152	func waitForBufferSignal(src io.Reader, sink io.Writer,
153	signal string, deadline time.Duration) error {	×
154		×
155	var err error	×
156	errChan := make(chan error)	×
157		×
158	go func() {	×
159	stdoutRdr := bufio.NewReader(src)	×
160	for {	×
161	line, err := stdoutRdr.ReadString('\n')	×
162	if err != nil {	×
163	errChan <- err	×
164	break	×
165	}
166	if strings.Contains(line, signal) {	×
167	errChan <- nil	×
168	break	×
169	}
170	_, err = sink.Write([]byte(line + "\n"))	×
171	if err != nil {	×
172	errChan <- err	×
173	break	×
174	}
175	}
176	}()
177
178	select {	×
179	case err = <-errChan:	×
180	// Error from goroutine
181	case <-time.After(deadline):	×
182	err = errors.New("Input deadline exceeded")	×
183	}
184	return err	×
185	}

mendersoftware / mender-artifact / 1979486890

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