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|
package sshclient
import (
"bufio"
"context"
"fmt"
"net"
"net/url"
"os"
"os/user"
"path/filepath"
"strconv"
"sync"
"time"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/knownhosts"
)
var (
homedirOnce sync.Once
homedir string
)
// Modified version of podman ssh client library, until a shared module exists
type Bastion struct {
Client *ssh.Client
Config *ssh.ClientConfig
Host string
Port string
Path string
connect ConnectCallback
}
type ConnectCallback func(ctx context.Context, bastion *Bastion) (net.Conn, error)
func PublicKey(path string, passphrase []byte) (ssh.Signer, error) {
key, err := os.ReadFile(path)
if err != nil {
return nil, err
}
signer, err := ssh.ParsePrivateKey(key)
if err != nil {
if _, ok := err.(*ssh.PassphraseMissingError); !ok {
return nil, err
}
return ssh.ParsePrivateKeyWithPassphrase(key, passphrase)
}
return signer, nil
}
func HostKey(host string) ssh.PublicKey {
// parse OpenSSH known_hosts file
// ssh or use ssh-keyscan to get initial key
knownHosts := filepath.Join(getHome(), ".ssh", "known_hosts")
fd, err := os.Open(knownHosts)
if err != nil {
logrus.Error(err)
return nil
}
// support -H parameter for ssh-keyscan
hashhost := knownhosts.HashHostname(host)
scanner := bufio.NewScanner(fd)
for scanner.Scan() {
_, hosts, key, _, _, err := ssh.ParseKnownHosts(scanner.Bytes())
if err != nil {
logrus.Errorf("Failed to parse known_hosts: %s", scanner.Text())
continue
}
for _, h := range hosts {
if h == host || h == hashhost {
return key
}
}
}
return nil
}
func CreateBastion(_url *url.URL, passPhrase string, identity string, initial net.Conn, connect ConnectCallback) (*Bastion, error) {
var authMethods []ssh.AuthMethod
if len(identity) > 0 {
s, err := PublicKey(identity, []byte(passPhrase))
if err != nil {
return nil, errors.Wrapf(err, "failed to parse identity %q", identity)
}
authMethods = append(authMethods, ssh.PublicKeys(s))
}
if pw, found := _url.User.Password(); found {
authMethods = append(authMethods, ssh.Password(pw))
}
if len(authMethods) == 0 {
return nil, errors.New("No available auth methods")
}
port := _url.Port()
if port == "" {
port = "22"
}
secure, _ := strconv.ParseBool(_url.Query().Get("secure"))
callback := ssh.InsecureIgnoreHostKey() // #nosec
if secure {
host := _url.Hostname()
if port != "22" {
host = fmt.Sprintf("[%s]:%s", host, port)
}
key := HostKey(host)
if key != nil {
callback = ssh.FixedHostKey(key)
}
}
config := &ssh.ClientConfig{
User: _url.User.Username(),
Auth: authMethods,
HostKeyCallback: callback,
HostKeyAlgorithms: []string{
ssh.KeyAlgoRSA,
ssh.KeyAlgoDSA,
ssh.KeyAlgoECDSA256,
ssh.KeyAlgoECDSA384,
ssh.KeyAlgoECDSA521,
ssh.KeyAlgoED25519,
},
Timeout: 5 * time.Second,
}
if connect == nil {
connect = func(_ context.Context, bastion *Bastion) (net.Conn, error) {
conn, err := net.DialTimeout("tcp",
net.JoinHostPort(bastion.Host, bastion.Port),
bastion.Config.Timeout,
)
return conn, err
}
}
bastion := Bastion{nil, config, _url.Hostname(), port, _url.Path, connect}
return &bastion, bastion.reconnect(context.Background(), initial)
}
func (bastion *Bastion) Reconnect(ctx context.Context) error {
return bastion.reconnect(ctx, nil)
}
func (bastion *Bastion) Close() {
if bastion.Client != nil {
bastion.Client.Close()
}
}
func (bastion *Bastion) reconnect(ctx context.Context, conn net.Conn) error {
var err error
if conn == nil {
conn, err = bastion.connect(ctx, bastion)
}
if err != nil {
return errors.Wrapf(err, "Connection to bastion host (%s) failed", bastion.Host)
}
addr := net.JoinHostPort(bastion.Host, bastion.Port)
c, chans, reqs, err := ssh.NewClientConn(conn, addr, bastion.Config)
if err != nil {
return err
}
bastion.Client = ssh.NewClient(c, chans, reqs)
return nil
}
func getHome() string {
homedirOnce.Do(func() {
env, err := os.UserHomeDir()
if env == "" || err != nil {
usr, err := user.LookupId(fmt.Sprintf("%d", os.Getuid()))
if err != nil {
logrus.Error("Could not determine user home directory!")
homedir = ""
return
}
homedir = usr.HomeDir
return
}
homedir = env
})
return homedir
}
|
