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package sftpfs
import (
"errors"
"fmt"
"io"
"io/fs"
"net"
"os"
"path"
"path/filepath"
"strings"
"sync"
"github.com/pkg/sftp"
"gitlab.com/rhogenson/ccp/internal/wfs"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
"golang.org/x/crypto/ssh/knownhosts"
"golang.org/x/term"
)
var (
_ wfs.FS = (*FS)(nil)
_ wfs.ReadLinkFS = (*FS)(nil)
_ fs.StatFS = (*FS)(nil)
_ fs.StatFS = (*FS)(nil)
_ fs.ReadDirFS = (*FS)(nil)
)
type FS struct {
User, Host string
conn *sftp.Client
sshConn *ssh.Client
}
var sshAgent = sync.OnceValue(func() agent.ExtendedAgent {
socket := os.Getenv("SSH_AUTH_SOCK")
if socket == "" {
return nil
}
conn, err := net.Dial("unix", socket)
if err != nil {
return nil
}
return agent.NewClient(conn)
})
func sshKeys() ([]ssh.Signer, error) {
sshAgent := sshAgent()
if sshAgent != nil {
if signers, err := sshAgent.Signers(); err == nil && len(signers) > 0 {
return signers, nil
}
}
sshDir := filepath.Join(os.Getenv("HOME"), ".ssh")
sshFiles, err := os.ReadDir(sshDir)
if len(sshFiles) == 0 {
return nil, err
}
var keys []ssh.Signer
var passwordProtectedKey []byte
var passwordProtectedKeyFile string
for _, f := range sshFiles {
if f.Name() == "known_hosts" || strings.HasSuffix(f.Name(), ".pub") {
continue
}
fileName := filepath.Join(sshDir, f.Name())
keyBytes, err := os.ReadFile(fileName)
if err != nil {
continue
}
key, err := ssh.ParsePrivateKey(keyBytes)
if err != nil {
if passwordProtectedKey == nil && errors.As(err, new(*ssh.PassphraseMissingError)) {
passwordProtectedKey = keyBytes
passwordProtectedKeyFile = fileName
}
continue
}
keys = append(keys, key)
}
if len(keys) == 0 && passwordProtectedKey != nil {
fmt.Fprintf(os.Stderr, "Enter password for %s: ", passwordProtectedKeyFile)
for i := range 3 {
if i > 0 {
fmt.Fprintf(os.Stderr, "Incorrect password, try again: ")
}
password, err := term.ReadPassword(int(os.Stdin.Fd()))
fmt.Fprintln(os.Stderr)
if err != nil {
return nil, err
}
key, err := ssh.ParseRawPrivateKeyWithPassphrase(passwordProtectedKey, password)
if err != nil {
continue
}
if sshAgent != nil {
sshAgent.Add(agent.AddedKey{PrivateKey: key})
}
signer, err := ssh.NewSignerFromKey(key)
if err != nil {
return nil, err
}
return []ssh.Signer{signer}, nil
}
return nil, errors.New("user couldn't remember her password")
}
return keys, nil
}
func appendToKnownHosts(hostname string, key ssh.PublicKey) error {
f, err := os.OpenFile(path.Join(os.Getenv("HOME"), ".ssh/known_hosts"), os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0600)
if err != nil {
return err
}
defer f.Close()
if _, err := f.WriteString(knownhosts.Line([]string{hostname}, key) + "\n"); err != nil {
return err
}
return f.Close()
}
func Dial(target string) (*FS, error) {
knownHostChecker, err := knownhosts.New(path.Join(os.Getenv("HOME"), ".ssh/known_hosts"))
if err != nil {
knownHostChecker = func(string, net.Addr, ssh.PublicKey) error { return &knownhosts.KeyError{} }
}
var user string
if i := strings.Index(target, "@"); i >= 0 {
user, target = target[:i], target[i+1:]
} else {
user = os.Getenv("USER")
}
sshConn, err := ssh.Dial("tcp", target+":22", &ssh.ClientConfig{
User: user,
Auth: []ssh.AuthMethod{
ssh.PublicKeysCallback(sshKeys),
ssh.RetryableAuthMethod(ssh.PasswordCallback(func() (string, error) {
fmt.Fprintf(os.Stderr, "Enter password for %s@%s: ", user, target)
password, err := term.ReadPassword(int(os.Stdin.Fd()))
fmt.Fprintln(os.Stderr)
return string(password), err
}), 3),
},
HostKeyCallback: func(hostname string, remote net.Addr, key ssh.PublicKey) error {
err := knownHostChecker(hostname, remote, key)
if err == nil {
return nil
}
var keyErr *knownhosts.KeyError
if !errors.As(err, &keyErr) || len(keyErr.Want) > 0 {
return err
}
appendToKnownHosts(hostname, key)
return nil
},
})
if err != nil {
return nil, err
}
sftpConn, err := sftp.NewClient(sshConn)
if err != nil {
sshConn.Close()
return nil, err
}
return &FS{
User: user,
Host: target,
conn: sftpConn,
sshConn: sshConn,
}, nil
}
func (f *FS) Close() error {
sftpErr := f.conn.Close()
if err := f.sshConn.Close(); err != nil {
return err
}
return sftpErr
}
func (f *FS) Open(name string) (fs.File, error) {
return f.conn.Open(name)
}
func (f *FS) ReadDir(name string) ([]fs.DirEntry, error) {
entriesFileInfo, err := f.conn.ReadDir(name)
entries := make([]fs.DirEntry, len(entriesFileInfo))
for i, entry := range entriesFileInfo {
entries[i] = fs.FileInfoToDirEntry(entry)
}
return entries, err
}
func (f *FS) Stat(name string) (fs.FileInfo, error) {
return f.conn.Stat(name)
}
func (f *FS) Lstat(name string) (fs.FileInfo, error) {
return f.conn.Lstat(name)
}
func (f *FS) ReadLink(name string) (string, error) {
return f.conn.ReadLink(name)
}
func (f *FS) Create(name string, perm fs.FileMode) (io.WriteCloser, error) {
file, err := f.conn.Create(name)
if err != nil {
return nil, err
}
if err := file.Chmod(perm); err != nil {
file.Close()
return nil, err
}
return file, nil
}
func (f *FS) Remove(name string) error {
return f.conn.Remove(name)
}
func (f *FS) Mkdir(name string) error {
return f.conn.Mkdir(name)
}
func (f *FS) Symlink(oldname, newname string) error {
return f.conn.Symlink(oldname, newname)
}
func (f *FS) Chmod(name string, mode fs.FileMode) error {
return f.conn.Chmod(name, mode)
}
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