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package main
import (
"context"
"fmt"
"io"
"net"
"os"
"path/filepath"
"sync"
"time"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
"golang.org/x/crypto/ssh/knownhosts"
)
type sshClient struct {
agentConn net.Conn
client *ssh.Client
}
func newSSHClient(context context.Context,
getenv func(string) string,
destination string,
) (*sshClient, error) {
var sshc sshClient
var err error
socket := getenv("SSH_AUTH_SOCK")
if sshc.agentConn, err = net.Dial("unix", socket); err != nil {
return nil, fmt.Errorf("failed to open SSH_AUTH_SOCK: %+v", err)
}
agentClient := agent.NewClient(sshc.agentConn)
hostKeyCallback, err := knownhosts.New(filepath.Join(getenv("HOME"), ".ssh/known_hosts"))
if err != nil {
return nil, fmt.Errorf("could not create hostkeycallback function: %+v", err)
}
config := &ssh.ClientConfig{
User: "root",
Auth: []ssh.AuthMethod{
ssh.PublicKeysCallback(agentClient.Signers),
},
HostKeyCallback: hostKeyCallback,
}
sshc.client, err = ssh.Dial("tcp", destination, config)
if err != nil {
return nil, fmt.Errorf("failed to dial: %+v", err)
}
return &sshc, nil
}
func (sshc *sshClient) Close() error {
if err := sshc.client.Close(); err != nil {
return err
}
if err := sshc.agentConn.Close(); err != nil {
return err
}
return nil
}
func (sshc *sshClient) SendFile(ctx context.Context,
stdout, stderr io.Writer,
filename string,
) (err error) {
session, err := sshc.client.NewSession()
if err != nil {
return fmt.Errorf("sshClient failed to create session: %+v", err)
}
defer func() {
if e := session.Close(); err == nil && e != io.EOF {
err = e
}
}()
file, err := os.Open(filename)
if err != nil {
return fmt.Errorf("sshClient failed to open file: %+v", err)
}
defer func() {
if e := file.Close(); err == nil {
err = e
}
}()
fi, err := file.Stat()
if err != nil {
return fmt.Errorf("sshClient failed to stat file: %+v", err)
}
w, err := session.StdinPipe()
if err != nil {
return fmt.Errorf("sshClient failed to open session stdin pipe: %+v", err)
}
wg := sync.WaitGroup{}
wg.Add(2)
errCh := make(chan error, 2)
session.Stdout = stdout
session.Stderr = stderr
if err = session.Start("scp -t /usr/local/bin/gonf-run"); err != nil {
return fmt.Errorf("sshClient failed to run scp: %+v", err)
}
go func() {
defer wg.Done()
if e := session.Wait(); e != nil {
errCh <- e
}
}()
go func() {
defer wg.Done()
defer func() {
if e := w.Close(); e != nil {
errCh <- e
}
}()
// Write "C{mode} {size} {filename}\n"
if _, e := fmt.Fprintf(w, "C%#o %d %s\n", 0700, fi.Size(), "gonf-run"); e != nil {
errCh <- e
return
}
// Write the file's contents.
if _, e := io.Copy(w, file); e != nil {
errCh <- e
return
}
// End with a null byte.
if _, e := fmt.Fprint(w, "\x00"); e != nil {
errCh <- e
}
}()
var cancel context.CancelFunc
ctx, cancel = context.WithTimeout(ctx, 60*time.Second)
defer cancel()
// wait for all waitgroup.Done() or the timeout
c := make(chan struct{})
go func() {
wg.Wait()
close(c)
}()
select {
case <-c:
case <-ctx.Done():
return ctx.Err()
}
close(errCh)
for err := range errCh {
if err != nil {
return err
}
}
return nil
}
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