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// Copyright 2014 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package ssh
import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strings"
"sync"
"github.com/juju/collections/set"
"github.com/juju/utils/v2"
"golang.org/x/crypto/ssh"
)
const clientKeyName = "juju_id_rsa"
// PublicKeySuffix is the file extension for public key files.
const PublicKeySuffix = ".pub"
var (
clientKeysMutex sync.Mutex
// clientKeys is a cached map of private key filenames
// to ssh.Signers. The private keys are those loaded
// from the client key directory, passed to LoadClientKeys.
clientKeys map[string]ssh.Signer
)
// LoadClientKeys loads the client SSH keys from the
// specified directory, and caches them as a process-wide
// global. If the directory does not exist, it is created;
// if the directory did not exist, or contains no keys, it
// is populated with a new key pair.
//
// If the directory exists, then all pairs of files where one
// has the same name as the other + ".pub" will be loaded as
// private/public key pairs.
//
// Calls to LoadClientKeys will clear the previously loaded
// keys, and recompute the keys.
func LoadClientKeys(dir string) error {
clientKeysMutex.Lock()
defer clientKeysMutex.Unlock()
dir, err := utils.NormalizePath(dir)
if err != nil {
return err
}
if _, err := os.Stat(dir); err == nil {
keys, err := loadClientKeys(dir)
if err != nil {
return err
} else if len(keys) > 0 {
clientKeys = keys
return nil
}
// Directory exists but contains no keys;
// fall through and create one.
}
if err := os.MkdirAll(dir, 0700); err != nil {
return err
}
keyfile, key, err := generateClientKey(dir)
if err != nil {
os.RemoveAll(dir)
return err
}
clientKeys = map[string]ssh.Signer{keyfile: key}
return nil
}
// ClearClientKeys clears the client keys cached in memory.
func ClearClientKeys() {
clientKeysMutex.Lock()
defer clientKeysMutex.Unlock()
clientKeys = nil
}
func generateClientKey(dir string) (keyfile string, key ssh.Signer, err error) {
private, public, err := GenerateKey("juju-client-key")
if err != nil {
return "", nil, err
}
clientPrivateKey, err := ssh.ParsePrivateKey([]byte(private))
if err != nil {
return "", nil, err
}
privkeyFilename := filepath.Join(dir, clientKeyName)
if err = ioutil.WriteFile(privkeyFilename, []byte(private), 0600); err != nil {
return "", nil, err
}
if err := ioutil.WriteFile(privkeyFilename+PublicKeySuffix, []byte(public), 0600); err != nil {
os.Remove(privkeyFilename)
return "", nil, err
}
return privkeyFilename, clientPrivateKey, nil
}
func loadClientKeys(dir string) (map[string]ssh.Signer, error) {
publicKeyFiles, err := publicKeyFiles(dir)
if err != nil {
return nil, err
}
keys := make(map[string]ssh.Signer, len(publicKeyFiles))
for _, filename := range publicKeyFiles {
filename = filename[:len(filename)-len(PublicKeySuffix)]
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
keys[filename], err = ssh.ParsePrivateKey(data)
if err != nil {
return nil, fmt.Errorf("parsing key file %q: %v", filename, err)
}
}
return keys, nil
}
// privateKeys returns the private keys loaded by LoadClientKeys.
func privateKeys() (signers []ssh.Signer) {
clientKeysMutex.Lock()
defer clientKeysMutex.Unlock()
for _, key := range clientKeys {
signers = append(signers, key)
}
return signers
}
// PrivateKeyFiles returns the filenames of private SSH keys loaded by
// LoadClientKeys.
func PrivateKeyFiles() []string {
clientKeysMutex.Lock()
defer clientKeysMutex.Unlock()
keyfiles := make([]string, 0, len(clientKeys))
for f := range clientKeys {
keyfiles = append(keyfiles, f)
}
return keyfiles
}
// PublicKeyFiles returns the filenames of public SSH keys loaded by
// LoadClientKeys.
func PublicKeyFiles() []string {
privkeys := PrivateKeyFiles()
pubkeys := make([]string, len(privkeys))
for i, priv := range privkeys {
pubkeys[i] = priv + PublicKeySuffix
}
return pubkeys
}
// publicKeyFiles returns the filenames of public SSH keys
// in the specified directory (all the files ending with .pub).
func publicKeyFiles(clientKeysDir string) ([]string, error) {
if clientKeysDir == "" {
return nil, nil
}
var keys []string
dir, err := os.Open(clientKeysDir)
if err != nil {
return nil, err
}
names, err := dir.Readdirnames(-1)
dir.Close()
if err != nil {
return nil, err
}
candidates := set.NewStrings(names...)
for _, name := range names {
if !strings.HasSuffix(name, PublicKeySuffix) {
continue
}
// If the private key filename also exists, add the file.
priv := name[:len(name)-len(PublicKeySuffix)]
if candidates.Contains(priv) {
keys = append(keys, filepath.Join(dir.Name(), name))
}
}
return keys, nil
}
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