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@@ -0,0 +1,255 @@
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+package main
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+
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+import (
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+ "bytes"
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+ "crypto/rand"
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+ "crypto/subtle"
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+ "errors"
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+ "fmt"
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+ "sync"
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+ "time"
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+
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+ "golang.org/x/crypto/ssh"
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+ "golang.org/x/crypto/ssh/agent"
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+)
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+
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+type privKey struct {
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+ signer ssh.Signer
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+ comment string
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+ confirm bool
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+ expire *time.Time
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+}
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+
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+type ConfirmFunction func(comment string) bool
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+
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+type keyring struct {
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+ confirmFunction ConfirmFunction
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+
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+ mu sync.Mutex
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+ keys []privKey
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+
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+ locked bool
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+ passphrase []byte
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+}
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+
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+var errLocked = errors.New("agent: locked")
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+
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+
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+
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+func NewKeyring(confirmFunction ConfirmFunction) agent.ExtendedAgent {
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+ return &keyring{
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+ confirmFunction: confirmFunction,
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+ }
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+}
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+
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+
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+func (r *keyring) RemoveAll() error {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+ return errLocked
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+ }
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+
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+ r.keys = nil
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+ return nil
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+}
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+
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+
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+
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+func (r *keyring) removeLocked(want []byte) error {
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+ found := false
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+ for i := 0; i < len(r.keys); {
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+ if bytes.Equal(r.keys[i].signer.PublicKey().Marshal(), want) {
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+ found = true
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+ r.keys[i] = r.keys[len(r.keys)-1]
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+ r.keys = r.keys[:len(r.keys)-1]
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+ continue
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+ } else {
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+ i++
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+ }
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+ }
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+
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+ if !found {
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+ return errors.New("agent: key not found")
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+ }
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+ return nil
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+}
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+
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+
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+func (r *keyring) Remove(key ssh.PublicKey) error {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+ return errLocked
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+ }
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+
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+ return r.removeLocked(key.Marshal())
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+}
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+
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+
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+func (r *keyring) Lock(passphrase []byte) error {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+ return errLocked
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+ }
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+
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+ r.locked = true
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+ r.passphrase = passphrase
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+ return nil
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+}
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+
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+
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+func (r *keyring) Unlock(passphrase []byte) error {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if !r.locked {
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+ return errors.New("agent: not locked")
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+ }
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+ if 1 != subtle.ConstantTimeCompare(passphrase, r.passphrase) {
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+ return fmt.Errorf("agent: incorrect passphrase")
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+ }
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+
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+ r.locked = false
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+ r.passphrase = nil
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+ return nil
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+}
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+
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+
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+
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+
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+func (r *keyring) expireKeysLocked() {
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+ for _, k := range r.keys {
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+ if k.expire != nil && time.Now().After(*k.expire) {
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+ r.removeLocked(k.signer.PublicKey().Marshal())
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+ }
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+ }
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+}
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+
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+
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+func (r *keyring) List() ([]*agent.Key, error) {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+
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+ return nil, nil
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+ }
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+
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+ r.expireKeysLocked()
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+ var ids []*agent.Key
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+ for _, k := range r.keys {
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+ pub := k.signer.PublicKey()
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+ ids = append(ids, &agent.Key{
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+ Format: pub.Type(),
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+ Blob: pub.Marshal(),
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+ Comment: k.comment})
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+ }
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+ return ids, nil
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+}
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+
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+
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+
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+
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+func (r *keyring) Add(key agent.AddedKey) error {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+ return errLocked
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+ }
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+ signer, err := ssh.NewSignerFromKey(key.PrivateKey)
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+
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+ if err != nil {
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+ return err
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+ }
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+
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+ if cert := key.Certificate; cert != nil {
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+ signer, err = ssh.NewCertSigner(cert, signer)
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+ if err != nil {
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+ return err
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+ }
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+ }
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+
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+ p := privKey{
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+ signer: signer,
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+ comment: key.Comment,
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+ confirm: key.ConfirmBeforeUse,
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+ }
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+
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+ if key.LifetimeSecs > 0 {
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+ t := time.Now().Add(time.Duration(key.LifetimeSecs) * time.Second)
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+ p.expire = &t
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+ }
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+
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+ r.keys = append(r.keys, p)
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+
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+ return nil
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+}
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+
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+
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+func (r *keyring) Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error) {
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+ return r.SignWithFlags(key, data, 0)
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+}
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+
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+func (r *keyring) SignWithFlags(key ssh.PublicKey, data []byte, flags agent.SignatureFlags) (*ssh.Signature, error) {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+ return nil, errLocked
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+ }
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+
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+ r.expireKeysLocked()
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+ wanted := key.Marshal()
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+ for _, k := range r.keys {
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+ if bytes.Equal(k.signer.PublicKey().Marshal(), wanted) {
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+ if k.confirm {
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+ if !r.confirmFunction(k.comment) {
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+ return nil, fmt.Errorf("agent: confirmation failed")
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+ }
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+ }
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+ if flags == 0 {
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+ return k.signer.Sign(rand.Reader, data)
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+ } else {
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+ if algorithmSigner, ok := k.signer.(ssh.AlgorithmSigner); !ok {
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+ return nil, fmt.Errorf("agent: signature does not support non-default signature algorithm: %T", k.signer)
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+ } else {
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+ var algorithm string
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+ switch flags {
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+ case agent.SignatureFlagRsaSha256:
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+ algorithm = ssh.KeyAlgoRSASHA256
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+ case agent.SignatureFlagRsaSha512:
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+ algorithm = ssh.KeyAlgoRSASHA512
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+ default:
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+ return nil, fmt.Errorf("agent: unsupported signature flags: %d", flags)
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+ }
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+ return algorithmSigner.SignWithAlgorithm(rand.Reader, data, algorithm)
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+ }
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+ }
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+ }
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+ }
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+ return nil, errors.New("not found")
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+}
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+
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+
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+func (r *keyring) Signers() ([]ssh.Signer, error) {
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+ r.mu.Lock()
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+ defer r.mu.Unlock()
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+ if r.locked {
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+ return nil, errLocked
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+ }
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+
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+ r.expireKeysLocked()
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+ s := make([]ssh.Signer, 0, len(r.keys))
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+ for _, k := range r.keys {
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+ s = append(s, k.signer)
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+ }
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+ return s, nil
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+}
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+
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+
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+func (r *keyring) Extension(extensionType string, contents []byte) ([]byte, error) {
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+ return nil, agent.ErrExtensionUnsupported
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+}
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