Upgrading dependencies to include logrus.

vendor/golang.org/x/crypto/ssh/agent/client.go

@@ -0,0 +1,789 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package agent implements the ssh-agent protocol, and provides both
+// a client and a server. The client can talk to a standard ssh-agent
+// that uses UNIX sockets, and one could implement an alternative
+// ssh-agent process using the sample server.
+//
+// References:
+//  [PROTOCOL.agent]: https://tools.ietf.org/html/draft-miller-ssh-agent-00
+package agent // import "golang.org/x/crypto/ssh/agent"
+
+import (
+	"bytes"
+	"crypto/dsa"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rsa"
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math/big"
+	"sync"
+
+	"crypto"
+	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/ssh"
+)
+
+// SignatureFlags represent additional flags that can be passed to the signature
+// requests an defined in [PROTOCOL.agent] section 4.5.1.
+type SignatureFlags uint32
+
+// SignatureFlag values as defined in [PROTOCOL.agent] section 5.3.
+const (
+	SignatureFlagReserved SignatureFlags = 1 << iota
+	SignatureFlagRsaSha256
+	SignatureFlagRsaSha512
+)
+
+// Agent represents the capabilities of an ssh-agent.
+type Agent interface {
+	// List returns the identities known to the agent.
+	List() ([]*Key, error)
+
+	// Sign has the agent sign the data using a protocol 2 key as defined
+	// in [PROTOCOL.agent] section 2.6.2.
+	Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error)
+
+	// Add adds a private key to the agent.
+	Add(key AddedKey) error
+
+	// Remove removes all identities with the given public key.
+	Remove(key ssh.PublicKey) error
+
+	// RemoveAll removes all identities.
+	RemoveAll() error
+
+	// Lock locks the agent. Sign and Remove will fail, and List will empty an empty list.
+	Lock(passphrase []byte) error
+
+	// Unlock undoes the effect of Lock
+	Unlock(passphrase []byte) error
+
+	// Signers returns signers for all the known keys.
+	Signers() ([]ssh.Signer, error)
+}
+
+type ExtendedAgent interface {
+	Agent
+
+	// SignWithFlags signs like Sign, but allows for additional flags to be sent/received
+	SignWithFlags(key ssh.PublicKey, data []byte, flags SignatureFlags) (*ssh.Signature, error)
+
+	// Extension processes a custom extension request. Standard-compliant agents are not
+	// required to support any extensions, but this method allows agents to implement
+	// vendor-specific methods or add experimental features. See [PROTOCOL.agent] section 4.7.
+	// If agent extensions are unsupported entirely this method MUST return an
+	// ErrExtensionUnsupported error. Similarly, if just the specific extensionType in
+	// the request is unsupported by the agent then ErrExtensionUnsupported MUST be
+	// returned.
+	//
+	// In the case of success, since [PROTOCOL.agent] section 4.7 specifies that the contents
+	// of the response are unspecified (including the type of the message), the complete
+	// response will be returned as a []byte slice, including the "type" byte of the message.
+	Extension(extensionType string, contents []byte) ([]byte, error)
+}
+
+// ConstraintExtension describes an optional constraint defined by users.
+type ConstraintExtension struct {
+	// ExtensionName consist of a UTF-8 string suffixed by the
+	// implementation domain following the naming scheme defined
+	// in Section 4.2 of [RFC4251], e.g.  "foo@example.com".
+	ExtensionName string
+	// ExtensionDetails contains the actual content of the extended
+	// constraint.
+	ExtensionDetails []byte
+}
+
+// AddedKey describes an SSH key to be added to an Agent.
+type AddedKey struct {
+	// PrivateKey must be a *rsa.PrivateKey, *dsa.PrivateKey or
+	// *ecdsa.PrivateKey, which will be inserted into the agent.
+	PrivateKey interface{}
+	// Certificate, if not nil, is communicated to the agent and will be
+	// stored with the key.
+	Certificate *ssh.Certificate
+	// Comment is an optional, free-form string.
+	Comment string
+	// LifetimeSecs, if not zero, is the number of seconds that the
+	// agent will store the key for.
+	LifetimeSecs uint32
+	// ConfirmBeforeUse, if true, requests that the agent confirm with the
+	// user before each use of this key.
+	ConfirmBeforeUse bool
+	// ConstraintExtensions are the experimental or private-use constraints
+	// defined by users.
+	ConstraintExtensions []ConstraintExtension
+}
+
+// See [PROTOCOL.agent], section 3.
+const (
+	agentRequestV1Identities   = 1
+	agentRemoveAllV1Identities = 9
+
+	// 3.2 Requests from client to agent for protocol 2 key operations
+	agentAddIdentity         = 17
+	agentRemoveIdentity      = 18
+	agentRemoveAllIdentities = 19
+	agentAddIDConstrained    = 25
+
+	// 3.3 Key-type independent requests from client to agent
+	agentAddSmartcardKey            = 20
+	agentRemoveSmartcardKey         = 21
+	agentLock                       = 22
+	agentUnlock                     = 23
+	agentAddSmartcardKeyConstrained = 26
+
+	// 3.7 Key constraint identifiers
+	agentConstrainLifetime  = 1
+	agentConstrainConfirm   = 2
+	agentConstrainExtension = 3
+)
+
+// maxAgentResponseBytes is the maximum agent reply size that is accepted. This
+// is a sanity check, not a limit in the spec.
+const maxAgentResponseBytes = 16 << 20
+
+// Agent messages:
+// These structures mirror the wire format of the corresponding ssh agent
+// messages found in [PROTOCOL.agent].
+
+// 3.4 Generic replies from agent to client
+const agentFailure = 5
+
+type failureAgentMsg struct{}
+
+const agentSuccess = 6
+
+type successAgentMsg struct{}
+
+// See [PROTOCOL.agent], section 2.5.2.
+const agentRequestIdentities = 11
+
+type requestIdentitiesAgentMsg struct{}
+
+// See [PROTOCOL.agent], section 2.5.2.
+const agentIdentitiesAnswer = 12
+
+type identitiesAnswerAgentMsg struct {
+	NumKeys uint32 `sshtype:"12"`
+	Keys    []byte `ssh:"rest"`
+}
+
+// See [PROTOCOL.agent], section 2.6.2.
+const agentSignRequest = 13
+
+type signRequestAgentMsg struct {
+	KeyBlob []byte `sshtype:"13"`
+	Data    []byte
+	Flags   uint32
+}
+
+// See [PROTOCOL.agent], section 2.6.2.
+
+// 3.6 Replies from agent to client for protocol 2 key operations
+const agentSignResponse = 14
+
+type signResponseAgentMsg struct {
+	SigBlob []byte `sshtype:"14"`
+}
+
+type publicKey struct {
+	Format string
+	Rest   []byte `ssh:"rest"`
+}
+
+// 3.7 Key constraint identifiers
+type constrainLifetimeAgentMsg struct {
+	LifetimeSecs uint32 `sshtype:"1"`
+}
+
+type constrainExtensionAgentMsg struct {
+	ExtensionName    string `sshtype:"3"`
+	ExtensionDetails []byte
+
+	// Rest is a field used for parsing, not part of message
+	Rest []byte `ssh:"rest"`
+}
+
+// See [PROTOCOL.agent], section 4.7
+const agentExtension = 27
+const agentExtensionFailure = 28
+
+// ErrExtensionUnsupported indicates that an extension defined in
+// [PROTOCOL.agent] section 4.7 is unsupported by the agent. Specifically this
+// error indicates that the agent returned a standard SSH_AGENT_FAILURE message
+// as the result of a SSH_AGENTC_EXTENSION request. Note that the protocol
+// specification (and therefore this error) does not distinguish between a
+// specific extension being unsupported and extensions being unsupported entirely.
+var ErrExtensionUnsupported = errors.New("agent: extension unsupported")
+
+type extensionAgentMsg struct {
+	ExtensionType string `sshtype:"27"`
+	Contents      []byte
+}
+
+// Key represents a protocol 2 public key as defined in
+// [PROTOCOL.agent], section 2.5.2.
+type Key struct {
+	Format  string
+	Blob    []byte
+	Comment string
+}
+
+func clientErr(err error) error {
+	return fmt.Errorf("agent: client error: %v", err)
+}
+
+// String returns the storage form of an agent key with the format, base64
+// encoded serialized key, and the comment if it is not empty.
+func (k *Key) String() string {
+	s := string(k.Format) + " " + base64.StdEncoding.EncodeToString(k.Blob)
+
+	if k.Comment != "" {
+		s += " " + k.Comment
+	}
+
+	return s
+}
+
+// Type returns the public key type.
+func (k *Key) Type() string {
+	return k.Format
+}
+
+// Marshal returns key blob to satisfy the ssh.PublicKey interface.
+func (k *Key) Marshal() []byte {
+	return k.Blob
+}
+
+// Verify satisfies the ssh.PublicKey interface.
+func (k *Key) Verify(data []byte, sig *ssh.Signature) error {
+	pubKey, err := ssh.ParsePublicKey(k.Blob)
+	if err != nil {
+		return fmt.Errorf("agent: bad public key: %v", err)
+	}
+	return pubKey.Verify(data, sig)
+}
+
+type wireKey struct {
+	Format string
+	Rest   []byte `ssh:"rest"`
+}
+
+func parseKey(in []byte) (out *Key, rest []byte, err error) {
+	var record struct {
+		Blob    []byte
+		Comment string
+		Rest    []byte `ssh:"rest"`
+	}
+
+	if err := ssh.Unmarshal(in, &record); err != nil {
+		return nil, nil, err
+	}
+
+	var wk wireKey
+	if err := ssh.Unmarshal(record.Blob, &wk); err != nil {
+		return nil, nil, err
+	}
+
+	return &Key{
+		Format:  wk.Format,
+		Blob:    record.Blob,
+		Comment: record.Comment,
+	}, record.Rest, nil
+}
+
+// client is a client for an ssh-agent process.
+type client struct {
+	// conn is typically a *net.UnixConn
+	conn io.ReadWriter
+	// mu is used to prevent concurrent access to the agent
+	mu sync.Mutex
+}
+
+// NewClient returns an Agent that talks to an ssh-agent process over
+// the given connection.
+func NewClient(rw io.ReadWriter) ExtendedAgent {
+	return &client{conn: rw}
+}
+
+// call sends an RPC to the agent. On success, the reply is
+// unmarshaled into reply and replyType is set to the first byte of
+// the reply, which contains the type of the message.
+func (c *client) call(req []byte) (reply interface{}, err error) {
+	buf, err := c.callRaw(req)
+	if err != nil {
+		return nil, err
+	}
+	reply, err = unmarshal(buf)
+	if err != nil {
+		return nil, clientErr(err)
+	}
+	return reply, nil
+}
+
+// callRaw sends an RPC to the agent. On success, the raw
+// bytes of the response are returned; no unmarshalling is
+// performed on the response.
+func (c *client) callRaw(req []byte) (reply []byte, err error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	msg := make([]byte, 4+len(req))
+	binary.BigEndian.PutUint32(msg, uint32(len(req)))
+	copy(msg[4:], req)
+	if _, err = c.conn.Write(msg); err != nil {
+		return nil, clientErr(err)
+	}
+
+	var respSizeBuf [4]byte
+	if _, err = io.ReadFull(c.conn, respSizeBuf[:]); err != nil {
+		return nil, clientErr(err)
+	}
+	respSize := binary.BigEndian.Uint32(respSizeBuf[:])
+	if respSize > maxAgentResponseBytes {
+		return nil, clientErr(errors.New("response too large"))
+	}
+
+	buf := make([]byte, respSize)
+	if _, err = io.ReadFull(c.conn, buf); err != nil {
+		return nil, clientErr(err)
+	}
+	return buf, nil
+}
+
+func (c *client) simpleCall(req []byte) error {
+	resp, err := c.call(req)
+	if err != nil {
+		return err
+	}
+	if _, ok := resp.(*successAgentMsg); ok {
+		return nil
+	}
+	return errors.New("agent: failure")
+}
+
+func (c *client) RemoveAll() error {
+	return c.simpleCall([]byte{agentRemoveAllIdentities})
+}
+
+func (c *client) Remove(key ssh.PublicKey) error {
+	req := ssh.Marshal(&agentRemoveIdentityMsg{
+		KeyBlob: key.Marshal(),
+	})
+	return c.simpleCall(req)
+}
+
+func (c *client) Lock(passphrase []byte) error {
+	req := ssh.Marshal(&agentLockMsg{
+		Passphrase: passphrase,
+	})
+	return c.simpleCall(req)
+}
+
+func (c *client) Unlock(passphrase []byte) error {
+	req := ssh.Marshal(&agentUnlockMsg{
+		Passphrase: passphrase,
+	})
+	return c.simpleCall(req)
+}
+
+// List returns the identities known to the agent.
+func (c *client) List() ([]*Key, error) {
+	// see [PROTOCOL.agent] section 2.5.2.
+	req := []byte{agentRequestIdentities}
+
+	msg, err := c.call(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch msg := msg.(type) {
+	case *identitiesAnswerAgentMsg:
+		if msg.NumKeys > maxAgentResponseBytes/8 {
+			return nil, errors.New("agent: too many keys in agent reply")
+		}
+		keys := make([]*Key, msg.NumKeys)
+		data := msg.Keys
+		for i := uint32(0); i < msg.NumKeys; i++ {
+			var key *Key
+			var err error
+			if key, data, err = parseKey(data); err != nil {
+				return nil, err
+			}
+			keys[i] = key
+		}
+		return keys, nil
+	case *failureAgentMsg:
+		return nil, errors.New("agent: failed to list keys")
+	}
+	panic("unreachable")
+}
+
+// Sign has the agent sign the data using a protocol 2 key as defined
+// in [PROTOCOL.agent] section 2.6.2.
+func (c *client) Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error) {
+	return c.SignWithFlags(key, data, 0)
+}
+
+func (c *client) SignWithFlags(key ssh.PublicKey, data []byte, flags SignatureFlags) (*ssh.Signature, error) {
+	req := ssh.Marshal(signRequestAgentMsg{
+		KeyBlob: key.Marshal(),
+		Data:    data,
+		Flags:   uint32(flags),
+	})
+
+	msg, err := c.call(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch msg := msg.(type) {
+	case *signResponseAgentMsg:
+		var sig ssh.Signature
+		if err := ssh.Unmarshal(msg.SigBlob, &sig); err != nil {
+			return nil, err
+		}
+
+		return &sig, nil
+	case *failureAgentMsg:
+		return nil, errors.New("agent: failed to sign challenge")
+	}
+	panic("unreachable")
+}
+
+// unmarshal parses an agent message in packet, returning the parsed
+// form and the message type of packet.
+func unmarshal(packet []byte) (interface{}, error) {
+	if len(packet) < 1 {
+		return nil, errors.New("agent: empty packet")
+	}
+	var msg interface{}
+	switch packet[0] {
+	case agentFailure:
+		return new(failureAgentMsg), nil
+	case agentSuccess:
+		return new(successAgentMsg), nil
+	case agentIdentitiesAnswer:
+		msg = new(identitiesAnswerAgentMsg)
+	case agentSignResponse:
+		msg = new(signResponseAgentMsg)
+	case agentV1IdentitiesAnswer:
+		msg = new(agentV1IdentityMsg)
+	default:
+		return nil, fmt.Errorf("agent: unknown type tag %d", packet[0])
+	}
+	if err := ssh.Unmarshal(packet, msg); err != nil {
+		return nil, err
+	}
+	return msg, nil
+}
+
+type rsaKeyMsg struct {
+	Type        string `sshtype:"17|25"`
+	N           *big.Int
+	E           *big.Int
+	D           *big.Int
+	Iqmp        *big.Int // IQMP = Inverse Q Mod P
+	P           *big.Int
+	Q           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type dsaKeyMsg struct {
+	Type        string `sshtype:"17|25"`
+	P           *big.Int
+	Q           *big.Int
+	G           *big.Int
+	Y           *big.Int
+	X           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type ecdsaKeyMsg struct {
+	Type        string `sshtype:"17|25"`
+	Curve       string
+	KeyBytes    []byte
+	D           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type ed25519KeyMsg struct {
+	Type        string `sshtype:"17|25"`
+	Pub         []byte
+	Priv        []byte
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+// Insert adds a private key to the agent.
+func (c *client) insertKey(s interface{}, comment string, constraints []byte) error {
+	var req []byte
+	switch k := s.(type) {
+	case *rsa.PrivateKey:
+		if len(k.Primes) != 2 {
+			return fmt.Errorf("agent: unsupported RSA key with %d primes", len(k.Primes))
+		}
+		k.Precompute()
+		req = ssh.Marshal(rsaKeyMsg{
+			Type:        ssh.KeyAlgoRSA,
+			N:           k.N,
+			E:           big.NewInt(int64(k.E)),
+			D:           k.D,
+			Iqmp:        k.Precomputed.Qinv,
+			P:           k.Primes[0],
+			Q:           k.Primes[1],
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *dsa.PrivateKey:
+		req = ssh.Marshal(dsaKeyMsg{
+			Type:        ssh.KeyAlgoDSA,
+			P:           k.P,
+			Q:           k.Q,
+			G:           k.G,
+			Y:           k.Y,
+			X:           k.X,
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *ecdsa.PrivateKey:
+		nistID := fmt.Sprintf("nistp%d", k.Params().BitSize)
+		req = ssh.Marshal(ecdsaKeyMsg{
+			Type:        "ecdsa-sha2-" + nistID,
+			Curve:       nistID,
+			KeyBytes:    elliptic.Marshal(k.Curve, k.X, k.Y),
+			D:           k.D,
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *ed25519.PrivateKey:
+		req = ssh.Marshal(ed25519KeyMsg{
+			Type:        ssh.KeyAlgoED25519,
+			Pub:         []byte(*k)[32:],
+			Priv:        []byte(*k),
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	default:
+		return fmt.Errorf("agent: unsupported key type %T", s)
+	}
+
+	// if constraints are present then the message type needs to be changed.
+	if len(constraints) != 0 {
+		req[0] = agentAddIDConstrained
+	}
+
+	resp, err := c.call(req)
+	if err != nil {
+		return err
+	}
+	if _, ok := resp.(*successAgentMsg); ok {
+		return nil
+	}
+	return errors.New("agent: failure")
+}
+
+type rsaCertMsg struct {
+	Type        string `sshtype:"17|25"`
+	CertBytes   []byte
+	D           *big.Int
+	Iqmp        *big.Int // IQMP = Inverse Q Mod P
+	P           *big.Int
+	Q           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type dsaCertMsg struct {
+	Type        string `sshtype:"17|25"`
+	CertBytes   []byte
+	X           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type ecdsaCertMsg struct {
+	Type        string `sshtype:"17|25"`
+	CertBytes   []byte
+	D           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type ed25519CertMsg struct {
+	Type        string `sshtype:"17|25"`
+	CertBytes   []byte
+	Pub         []byte
+	Priv        []byte
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+// Add adds a private key to the agent. If a certificate is given,
+// that certificate is added instead as public key.
+func (c *client) Add(key AddedKey) error {
+	var constraints []byte
+
+	if secs := key.LifetimeSecs; secs != 0 {
+		constraints = append(constraints, ssh.Marshal(constrainLifetimeAgentMsg{secs})...)
+	}
+
+	if key.ConfirmBeforeUse {
+		constraints = append(constraints, agentConstrainConfirm)
+	}
+
+	cert := key.Certificate
+	if cert == nil {
+		return c.insertKey(key.PrivateKey, key.Comment, constraints)
+	}
+	return c.insertCert(key.PrivateKey, cert, key.Comment, constraints)
+}
+
+func (c *client) insertCert(s interface{}, cert *ssh.Certificate, comment string, constraints []byte) error {
+	var req []byte
+	switch k := s.(type) {
+	case *rsa.PrivateKey:
+		if len(k.Primes) != 2 {
+			return fmt.Errorf("agent: unsupported RSA key with %d primes", len(k.Primes))
+		}
+		k.Precompute()
+		req = ssh.Marshal(rsaCertMsg{
+			Type:        cert.Type(),
+			CertBytes:   cert.Marshal(),
+			D:           k.D,
+			Iqmp:        k.Precomputed.Qinv,
+			P:           k.Primes[0],
+			Q:           k.Primes[1],
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *dsa.PrivateKey:
+		req = ssh.Marshal(dsaCertMsg{
+			Type:        cert.Type(),
+			CertBytes:   cert.Marshal(),
+			X:           k.X,
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *ecdsa.PrivateKey:
+		req = ssh.Marshal(ecdsaCertMsg{
+			Type:        cert.Type(),
+			CertBytes:   cert.Marshal(),
+			D:           k.D,
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *ed25519.PrivateKey:
+		req = ssh.Marshal(ed25519CertMsg{
+			Type:        cert.Type(),
+			CertBytes:   cert.Marshal(),
+			Pub:         []byte(*k)[32:],
+			Priv:        []byte(*k),
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	default:
+		return fmt.Errorf("agent: unsupported key type %T", s)
+	}
+
+	// if constraints are present then the message type needs to be changed.
+	if len(constraints) != 0 {
+		req[0] = agentAddIDConstrained
+	}
+
+	signer, err := ssh.NewSignerFromKey(s)
+	if err != nil {
+		return err
+	}
+	if bytes.Compare(cert.Key.Marshal(), signer.PublicKey().Marshal()) != 0 {
+		return errors.New("agent: signer and cert have different public key")
+	}
+
+	resp, err := c.call(req)
+	if err != nil {
+		return err
+	}
+	if _, ok := resp.(*successAgentMsg); ok {
+		return nil
+	}
+	return errors.New("agent: failure")
+}
+
+// Signers provides a callback for client authentication.
+func (c *client) Signers() ([]ssh.Signer, error) {
+	keys, err := c.List()
+	if err != nil {
+		return nil, err
+	}
+
+	var result []ssh.Signer
+	for _, k := range keys {
+		result = append(result, &agentKeyringSigner{c, k})
+	}
+	return result, nil
+}
+
+type agentKeyringSigner struct {
+	agent *client
+	pub   ssh.PublicKey
+}
+
+func (s *agentKeyringSigner) PublicKey() ssh.PublicKey {
+	return s.pub
+}
+
+func (s *agentKeyringSigner) Sign(rand io.Reader, data []byte) (*ssh.Signature, error) {
+	// The agent has its own entropy source, so the rand argument is ignored.
+	return s.agent.Sign(s.pub, data)
+}
+
+func (s *agentKeyringSigner) SignWithOpts(rand io.Reader, data []byte, opts crypto.SignerOpts) (*ssh.Signature, error) {
+	var flags SignatureFlags
+	if opts != nil {
+		switch opts.HashFunc() {
+		case crypto.SHA256:
+			flags = SignatureFlagRsaSha256
+		case crypto.SHA512:
+			flags = SignatureFlagRsaSha512
+		}
+	}
+	return s.agent.SignWithFlags(s.pub, data, flags)
+}
+
+// Calls an extension method. It is up to the agent implementation as to whether or not
+// any particular extension is supported and may always return an error. Because the
+// type of the response is up to the implementation, this returns the bytes of the
+// response and does not attempt any type of unmarshalling.
+func (c *client) Extension(extensionType string, contents []byte) ([]byte, error) {
+	req := ssh.Marshal(extensionAgentMsg{
+		ExtensionType: extensionType,
+		Contents:      contents,
+	})
+	buf, err := c.callRaw(req)
+	if err != nil {
+		return nil, err
+	}
+	if len(buf) == 0 {
+		return nil, errors.New("agent: failure; empty response")
+	}
+	// [PROTOCOL.agent] section 4.7 indicates that an SSH_AGENT_FAILURE message
+	// represents an agent that does not support the extension
+	if buf[0] == agentFailure {
+		return nil, ErrExtensionUnsupported
+	}
+	if buf[0] == agentExtensionFailure {
+		return nil, errors.New("agent: generic extension failure")
+	}
+
+	return buf, nil
+}

vendor/golang.org/x/crypto/ssh/agent/client_test.go

@@ -0,0 +1,466 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent
+
+import (
+	"bytes"
+	"crypto/rand"
+	"errors"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"testing"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// startOpenSSHAgent executes ssh-agent, and returns an Agent interface to it.
+func startOpenSSHAgent(t *testing.T) (client ExtendedAgent, socket string, cleanup func()) {
+	if testing.Short() {
+		// ssh-agent is not always available, and the key
+		// types supported vary by platform.
+		t.Skip("skipping test due to -short")
+	}
+
+	bin, err := exec.LookPath("ssh-agent")
+	if err != nil {
+		t.Skip("could not find ssh-agent")
+	}
+
+	cmd := exec.Command(bin, "-s")
+	out, err := cmd.Output()
+	if err != nil {
+		t.Fatalf("cmd.Output: %v", err)
+	}
+
+	/* Output looks like:
+
+		   SSH_AUTH_SOCK=/tmp/ssh-P65gpcqArqvH/agent.15541; export SSH_AUTH_SOCK;
+	           SSH_AGENT_PID=15542; export SSH_AGENT_PID;
+	           echo Agent pid 15542;
+	*/
+	fields := bytes.Split(out, []byte(";"))
+	line := bytes.SplitN(fields[0], []byte("="), 2)
+	line[0] = bytes.TrimLeft(line[0], "\n")
+	if string(line[0]) != "SSH_AUTH_SOCK" {
+		t.Fatalf("could not find key SSH_AUTH_SOCK in %q", fields[0])
+	}
+	socket = string(line[1])
+
+	line = bytes.SplitN(fields[2], []byte("="), 2)
+	line[0] = bytes.TrimLeft(line[0], "\n")
+	if string(line[0]) != "SSH_AGENT_PID" {
+		t.Fatalf("could not find key SSH_AGENT_PID in %q", fields[2])
+	}
+	pidStr := line[1]
+	pid, err := strconv.Atoi(string(pidStr))
+	if err != nil {
+		t.Fatalf("Atoi(%q): %v", pidStr, err)
+	}
+
+	conn, err := net.Dial("unix", string(socket))
+	if err != nil {
+		t.Fatalf("net.Dial: %v", err)
+	}
+
+	ac := NewClient(conn)
+	return ac, socket, func() {
+		proc, _ := os.FindProcess(pid)
+		if proc != nil {
+			proc.Kill()
+		}
+		conn.Close()
+		os.RemoveAll(filepath.Dir(socket))
+	}
+}
+
+func startAgent(t *testing.T, agent Agent) (client ExtendedAgent, cleanup func()) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	go ServeAgent(agent, c2)
+
+	return NewClient(c1), func() {
+		c1.Close()
+		c2.Close()
+	}
+}
+
+// startKeyringAgent uses Keyring to simulate a ssh-agent Server and returns a client.
+func startKeyringAgent(t *testing.T) (client ExtendedAgent, cleanup func()) {
+	return startAgent(t, NewKeyring())
+}
+
+func testOpenSSHAgent(t *testing.T, key interface{}, cert *ssh.Certificate, lifetimeSecs uint32) {
+	agent, _, cleanup := startOpenSSHAgent(t)
+	defer cleanup()
+
+	testAgentInterface(t, agent, key, cert, lifetimeSecs)
+}
+
+func testKeyringAgent(t *testing.T, key interface{}, cert *ssh.Certificate, lifetimeSecs uint32) {
+	agent, cleanup := startKeyringAgent(t)
+	defer cleanup()
+
+	testAgentInterface(t, agent, key, cert, lifetimeSecs)
+}
+
+func testAgentInterface(t *testing.T, agent ExtendedAgent, key interface{}, cert *ssh.Certificate, lifetimeSecs uint32) {
+	signer, err := ssh.NewSignerFromKey(key)
+	if err != nil {
+		t.Fatalf("NewSignerFromKey(%T): %v", key, err)
+	}
+	// The agent should start up empty.
+	if keys, err := agent.List(); err != nil {
+		t.Fatalf("RequestIdentities: %v", err)
+	} else if len(keys) > 0 {
+		t.Fatalf("got %d keys, want 0: %v", len(keys), keys)
+	}
+
+	// Attempt to insert the key, with certificate if specified.
+	var pubKey ssh.PublicKey
+	if cert != nil {
+		err = agent.Add(AddedKey{
+			PrivateKey:   key,
+			Certificate:  cert,
+			Comment:      "comment",
+			LifetimeSecs: lifetimeSecs,
+		})
+		pubKey = cert
+	} else {
+		err = agent.Add(AddedKey{PrivateKey: key, Comment: "comment", LifetimeSecs: lifetimeSecs})
+		pubKey = signer.PublicKey()
+	}
+	if err != nil {
+		t.Fatalf("insert(%T): %v", key, err)
+	}
+
+	// Did the key get inserted successfully?
+	if keys, err := agent.List(); err != nil {
+		t.Fatalf("List: %v", err)
+	} else if len(keys) != 1 {
+		t.Fatalf("got %v, want 1 key", keys)
+	} else if keys[0].Comment != "comment" {
+		t.Fatalf("key comment: got %v, want %v", keys[0].Comment, "comment")
+	} else if !bytes.Equal(keys[0].Blob, pubKey.Marshal()) {
+		t.Fatalf("key mismatch")
+	}
+
+	// Can the agent make a valid signature?
+	data := []byte("hello")
+	sig, err := agent.Sign(pubKey, data)
+	if err != nil {
+		t.Fatalf("Sign(%s): %v", pubKey.Type(), err)
+	}
+
+	if err := pubKey.Verify(data, sig); err != nil {
+		t.Fatalf("Verify(%s): %v", pubKey.Type(), err)
+	}
+
+	// For tests on RSA keys, try signing with SHA-256 and SHA-512 flags
+	if pubKey.Type() == "ssh-rsa" {
+		sshFlagTest := func(flag SignatureFlags, expectedSigFormat string) {
+			sig, err = agent.SignWithFlags(pubKey, data, flag)
+			if err != nil {
+				t.Fatalf("SignWithFlags(%s): %v", pubKey.Type(), err)
+			}
+			if sig.Format != expectedSigFormat {
+				t.Fatalf("Signature format didn't match expected value: %s != %s", sig.Format, expectedSigFormat)
+			}
+			if err := pubKey.Verify(data, sig); err != nil {
+				t.Fatalf("Verify(%s): %v", pubKey.Type(), err)
+			}
+		}
+		sshFlagTest(0, ssh.SigAlgoRSA)
+		sshFlagTest(SignatureFlagRsaSha256, ssh.SigAlgoRSASHA2256)
+		sshFlagTest(SignatureFlagRsaSha512, ssh.SigAlgoRSASHA2512)
+	}
+
+	// If the key has a lifetime, is it removed when it should be?
+	if lifetimeSecs > 0 {
+		time.Sleep(time.Second*time.Duration(lifetimeSecs) + 100*time.Millisecond)
+		keys, err := agent.List()
+		if err != nil {
+			t.Fatalf("List: %v", err)
+		}
+		if len(keys) > 0 {
+			t.Fatalf("key not expired")
+		}
+	}
+
+}
+
+func TestAgent(t *testing.T) {
+	for _, keyType := range []string{"rsa", "dsa", "ecdsa", "ed25519"} {
+		testOpenSSHAgent(t, testPrivateKeys[keyType], nil, 0)
+		testKeyringAgent(t, testPrivateKeys[keyType], nil, 0)
+	}
+}
+
+func TestCert(t *testing.T) {
+	cert := &ssh.Certificate{
+		Key:         testPublicKeys["rsa"],
+		ValidBefore: ssh.CertTimeInfinity,
+		CertType:    ssh.UserCert,
+	}
+	cert.SignCert(rand.Reader, testSigners["ecdsa"])
+
+	testOpenSSHAgent(t, testPrivateKeys["rsa"], cert, 0)
+	testKeyringAgent(t, testPrivateKeys["rsa"], cert, 0)
+}
+
+// netPipe is analogous to net.Pipe, but it uses a real net.Conn, and
+// therefore is buffered (net.Pipe deadlocks if both sides start with
+// a write.)
+func netPipe() (net.Conn, net.Conn, error) {
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		listener, err = net.Listen("tcp", "[::1]:0")
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+	defer listener.Close()
+	c1, err := net.Dial("tcp", listener.Addr().String())
+	if err != nil {
+		return nil, nil, err
+	}
+
+	c2, err := listener.Accept()
+	if err != nil {
+		c1.Close()
+		return nil, nil, err
+	}
+
+	return c1, c2, nil
+}
+
+func TestServerResponseTooLarge(t *testing.T) {
+	a, b, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+
+	defer a.Close()
+	defer b.Close()
+
+	var response identitiesAnswerAgentMsg
+	response.NumKeys = 1
+	response.Keys = make([]byte, maxAgentResponseBytes+1)
+
+	agent := NewClient(a)
+	go func() {
+		n, _ := b.Write(ssh.Marshal(response))
+		if n < 4 {
+			t.Fatalf("At least 4 bytes (the response size) should have been successfully written: %d < 4", n)
+		}
+	}()
+	_, err = agent.List()
+	if err == nil {
+		t.Fatal("Did not get error result")
+	}
+	if err.Error() != "agent: client error: response too large" {
+		t.Fatal("Did not get expected error result")
+	}
+}
+
+func TestAuth(t *testing.T) {
+	agent, _, cleanup := startOpenSSHAgent(t)
+	defer cleanup()
+
+	a, b, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+
+	defer a.Close()
+	defer b.Close()
+
+	if err := agent.Add(AddedKey{PrivateKey: testPrivateKeys["rsa"], Comment: "comment"}); err != nil {
+		t.Errorf("Add: %v", err)
+	}
+
+	serverConf := ssh.ServerConfig{}
+	serverConf.AddHostKey(testSigners["rsa"])
+	serverConf.PublicKeyCallback = func(c ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
+		if bytes.Equal(key.Marshal(), testPublicKeys["rsa"].Marshal()) {
+			return nil, nil
+		}
+
+		return nil, errors.New("pubkey rejected")
+	}
+
+	go func() {
+		conn, _, _, err := ssh.NewServerConn(a, &serverConf)
+		if err != nil {
+			t.Fatalf("Server: %v", err)
+		}
+		conn.Close()
+	}()
+
+	conf := ssh.ClientConfig{
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+	conf.Auth = append(conf.Auth, ssh.PublicKeysCallback(agent.Signers))
+	conn, _, _, err := ssh.NewClientConn(b, "", &conf)
+	if err != nil {
+		t.Fatalf("NewClientConn: %v", err)
+	}
+	conn.Close()
+}
+
+func TestLockOpenSSHAgent(t *testing.T) {
+	agent, _, cleanup := startOpenSSHAgent(t)
+	defer cleanup()
+	testLockAgent(agent, t)
+}
+
+func TestLockKeyringAgent(t *testing.T) {
+	agent, cleanup := startKeyringAgent(t)
+	defer cleanup()
+	testLockAgent(agent, t)
+}
+
+func testLockAgent(agent Agent, t *testing.T) {
+	if err := agent.Add(AddedKey{PrivateKey: testPrivateKeys["rsa"], Comment: "comment 1"}); err != nil {
+		t.Errorf("Add: %v", err)
+	}
+	if err := agent.Add(AddedKey{PrivateKey: testPrivateKeys["dsa"], Comment: "comment dsa"}); err != nil {
+		t.Errorf("Add: %v", err)
+	}
+	if keys, err := agent.List(); err != nil {
+		t.Errorf("List: %v", err)
+	} else if len(keys) != 2 {
+		t.Errorf("Want 2 keys, got %v", keys)
+	}
+
+	passphrase := []byte("secret")
+	if err := agent.Lock(passphrase); err != nil {
+		t.Errorf("Lock: %v", err)
+	}
+
+	if keys, err := agent.List(); err != nil {
+		t.Errorf("List: %v", err)
+	} else if len(keys) != 0 {
+		t.Errorf("Want 0 keys, got %v", keys)
+	}
+
+	signer, _ := ssh.NewSignerFromKey(testPrivateKeys["rsa"])
+	if _, err := agent.Sign(signer.PublicKey(), []byte("hello")); err == nil {
+		t.Fatalf("Sign did not fail")
+	}
+
+	if err := agent.Remove(signer.PublicKey()); err == nil {
+		t.Fatalf("Remove did not fail")
+	}
+
+	if err := agent.RemoveAll(); err == nil {
+		t.Fatalf("RemoveAll did not fail")
+	}
+
+	if err := agent.Unlock(nil); err == nil {
+		t.Errorf("Unlock with wrong passphrase succeeded")
+	}
+	if err := agent.Unlock(passphrase); err != nil {
+		t.Errorf("Unlock: %v", err)
+	}
+
+	if err := agent.Remove(signer.PublicKey()); err != nil {
+		t.Fatalf("Remove: %v", err)
+	}
+
+	if keys, err := agent.List(); err != nil {
+		t.Errorf("List: %v", err)
+	} else if len(keys) != 1 {
+		t.Errorf("Want 1 keys, got %v", keys)
+	}
+}
+
+func testOpenSSHAgentLifetime(t *testing.T) {
+	agent, _, cleanup := startOpenSSHAgent(t)
+	defer cleanup()
+	testAgentLifetime(t, agent)
+}
+
+func testKeyringAgentLifetime(t *testing.T) {
+	agent, cleanup := startKeyringAgent(t)
+	defer cleanup()
+	testAgentLifetime(t, agent)
+}
+
+func testAgentLifetime(t *testing.T, agent Agent) {
+	for _, keyType := range []string{"rsa", "dsa", "ecdsa"} {
+		// Add private keys to the agent.
+		err := agent.Add(AddedKey{
+			PrivateKey:   testPrivateKeys[keyType],
+			Comment:      "comment",
+			LifetimeSecs: 1,
+		})
+		if err != nil {
+			t.Fatalf("add: %v", err)
+		}
+		// Add certs to the agent.
+		cert := &ssh.Certificate{
+			Key:         testPublicKeys[keyType],
+			ValidBefore: ssh.CertTimeInfinity,
+			CertType:    ssh.UserCert,
+		}
+		cert.SignCert(rand.Reader, testSigners[keyType])
+		err = agent.Add(AddedKey{
+			PrivateKey:   testPrivateKeys[keyType],
+			Certificate:  cert,
+			Comment:      "comment",
+			LifetimeSecs: 1,
+		})
+		if err != nil {
+			t.Fatalf("add: %v", err)
+		}
+	}
+	time.Sleep(1100 * time.Millisecond)
+	if keys, err := agent.List(); err != nil {
+		t.Errorf("List: %v", err)
+	} else if len(keys) != 0 {
+		t.Errorf("Want 0 keys, got %v", len(keys))
+	}
+}
+
+type keyringExtended struct {
+	*keyring
+}
+
+func (r *keyringExtended) Extension(extensionType string, contents []byte) ([]byte, error) {
+	if extensionType != "my-extension@example.com" {
+		return []byte{agentExtensionFailure}, nil
+	}
+	return append([]byte{agentSuccess}, contents...), nil
+}
+
+func TestAgentExtensions(t *testing.T) {
+	agent, _, cleanup := startOpenSSHAgent(t)
+	defer cleanup()
+	result, err := agent.Extension("my-extension@example.com", []byte{0x00, 0x01, 0x02})
+	if err == nil {
+		t.Fatal("should have gotten agent extension failure")
+	}
+
+	agent, cleanup = startAgent(t, &keyringExtended{})
+	defer cleanup()
+	result, err = agent.Extension("my-extension@example.com", []byte{0x00, 0x01, 0x02})
+	if err != nil {
+		t.Fatalf("agent extension failure: %v", err)
+	}
+	if len(result) != 4 || !bytes.Equal(result, []byte{agentSuccess, 0x00, 0x01, 0x02}) {
+		t.Fatalf("agent extension result invalid: %v", result)
+	}
+
+	result, err = agent.Extension("bad-extension@example.com", []byte{0x00, 0x01, 0x02})
+	if err == nil {
+		t.Fatal("should have gotten agent extension failure")
+	}
+}

vendor/golang.org/x/crypto/ssh/agent/example_test.go

@@ -0,0 +1,41 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent_test
+
+import (
+	"log"
+	"net"
+	"os"
+
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/agent"
+)
+
+func ExampleClientAgent() {
+	// ssh-agent has a UNIX socket under $SSH_AUTH_SOCK
+	socket := os.Getenv("SSH_AUTH_SOCK")
+	conn, err := net.Dial("unix", socket)
+	if err != nil {
+		log.Fatalf("net.Dial: %v", err)
+	}
+	agentClient := agent.NewClient(conn)
+	config := &ssh.ClientConfig{
+		User: "username",
+		Auth: []ssh.AuthMethod{
+			// Use a callback rather than PublicKeys
+			// so we only consult the agent once the remote server
+			// wants it.
+			ssh.PublicKeysCallback(agentClient.Signers),
+		},
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+
+	sshc, err := ssh.Dial("tcp", "localhost:22", config)
+	if err != nil {
+		log.Fatalf("Dial: %v", err)
+	}
+	// .. use sshc
+	sshc.Close()
+}

vendor/golang.org/x/crypto/ssh/agent/forward.go

@@ -0,0 +1,103 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent
+
+import (
+	"errors"
+	"io"
+	"net"
+	"sync"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// RequestAgentForwarding sets up agent forwarding for the session.
+// ForwardToAgent or ForwardToRemote should be called to route
+// the authentication requests.
+func RequestAgentForwarding(session *ssh.Session) error {
+	ok, err := session.SendRequest("auth-agent-req@openssh.com", true, nil)
+	if err != nil {
+		return err
+	}
+	if !ok {
+		return errors.New("forwarding request denied")
+	}
+	return nil
+}
+
+// ForwardToAgent routes authentication requests to the given keyring.
+func ForwardToAgent(client *ssh.Client, keyring Agent) error {
+	channels := client.HandleChannelOpen(channelType)
+	if channels == nil {
+		return errors.New("agent: already have handler for " + channelType)
+	}
+
+	go func() {
+		for ch := range channels {
+			channel, reqs, err := ch.Accept()
+			if err != nil {
+				continue
+			}
+			go ssh.DiscardRequests(reqs)
+			go func() {
+				ServeAgent(keyring, channel)
+				channel.Close()
+			}()
+		}
+	}()
+	return nil
+}
+
+const channelType = "auth-agent@openssh.com"
+
+// ForwardToRemote routes authentication requests to the ssh-agent
+// process serving on the given unix socket.
+func ForwardToRemote(client *ssh.Client, addr string) error {
+	channels := client.HandleChannelOpen(channelType)
+	if channels == nil {
+		return errors.New("agent: already have handler for " + channelType)
+	}
+	conn, err := net.Dial("unix", addr)
+	if err != nil {
+		return err
+	}
+	conn.Close()
+
+	go func() {
+		for ch := range channels {
+			channel, reqs, err := ch.Accept()
+			if err != nil {
+				continue
+			}
+			go ssh.DiscardRequests(reqs)
+			go forwardUnixSocket(channel, addr)
+		}
+	}()
+	return nil
+}
+
+func forwardUnixSocket(channel ssh.Channel, addr string) {
+	conn, err := net.Dial("unix", addr)
+	if err != nil {
+		return
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		io.Copy(conn, channel)
+		conn.(*net.UnixConn).CloseWrite()
+		wg.Done()
+	}()
+	go func() {
+		io.Copy(channel, conn)
+		channel.CloseWrite()
+		wg.Done()
+	}()
+
+	wg.Wait()
+	conn.Close()
+	channel.Close()
+}

vendor/golang.org/x/crypto/ssh/agent/keyring.go

@@ -0,0 +1,241 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent
+
+import (
+	"bytes"
+	"crypto/rand"
+	"crypto/subtle"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+type privKey struct {
+	signer  ssh.Signer
+	comment string
+	expire  *time.Time
+}
+
+type keyring struct {
+	mu   sync.Mutex
+	keys []privKey
+
+	locked     bool
+	passphrase []byte
+}
+
+var errLocked = errors.New("agent: locked")
+
+// NewKeyring returns an Agent that holds keys in memory.  It is safe
+// for concurrent use by multiple goroutines.
+func NewKeyring() Agent {
+	return &keyring{}
+}
+
+// RemoveAll removes all identities.
+func (r *keyring) RemoveAll() error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		return errLocked
+	}
+
+	r.keys = nil
+	return nil
+}
+
+// removeLocked does the actual key removal. The caller must already be holding the
+// keyring mutex.
+func (r *keyring) removeLocked(want []byte) error {
+	found := false
+	for i := 0; i < len(r.keys); {
+		if bytes.Equal(r.keys[i].signer.PublicKey().Marshal(), want) {
+			found = true
+			r.keys[i] = r.keys[len(r.keys)-1]
+			r.keys = r.keys[:len(r.keys)-1]
+			continue
+		} else {
+			i++
+		}
+	}
+
+	if !found {
+		return errors.New("agent: key not found")
+	}
+	return nil
+}
+
+// Remove removes all identities with the given public key.
+func (r *keyring) Remove(key ssh.PublicKey) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		return errLocked
+	}
+
+	return r.removeLocked(key.Marshal())
+}
+
+// Lock locks the agent. Sign and Remove will fail, and List will return an empty list.
+func (r *keyring) Lock(passphrase []byte) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		return errLocked
+	}
+
+	r.locked = true
+	r.passphrase = passphrase
+	return nil
+}
+
+// Unlock undoes the effect of Lock
+func (r *keyring) Unlock(passphrase []byte) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if !r.locked {
+		return errors.New("agent: not locked")
+	}
+	if 1 != subtle.ConstantTimeCompare(passphrase, r.passphrase) {
+		return fmt.Errorf("agent: incorrect passphrase")
+	}
+
+	r.locked = false
+	r.passphrase = nil
+	return nil
+}
+
+// expireKeysLocked removes expired keys from the keyring. If a key was added
+// with a lifetimesecs contraint and seconds >= lifetimesecs seconds have
+// ellapsed, it is removed. The caller *must* be holding the keyring mutex.
+func (r *keyring) expireKeysLocked() {
+	for _, k := range r.keys {
+		if k.expire != nil && time.Now().After(*k.expire) {
+			r.removeLocked(k.signer.PublicKey().Marshal())
+		}
+	}
+}
+
+// List returns the identities known to the agent.
+func (r *keyring) List() ([]*Key, error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		// section 2.7: locked agents return empty.
+		return nil, nil
+	}
+
+	r.expireKeysLocked()
+	var ids []*Key
+	for _, k := range r.keys {
+		pub := k.signer.PublicKey()
+		ids = append(ids, &Key{
+			Format:  pub.Type(),
+			Blob:    pub.Marshal(),
+			Comment: k.comment})
+	}
+	return ids, nil
+}
+
+// Insert adds a private key to the keyring. If a certificate
+// is given, that certificate is added as public key. Note that
+// any constraints given are ignored.
+func (r *keyring) Add(key AddedKey) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		return errLocked
+	}
+	signer, err := ssh.NewSignerFromKey(key.PrivateKey)
+
+	if err != nil {
+		return err
+	}
+
+	if cert := key.Certificate; cert != nil {
+		signer, err = ssh.NewCertSigner(cert, signer)
+		if err != nil {
+			return err
+		}
+	}
+
+	p := privKey{
+		signer:  signer,
+		comment: key.Comment,
+	}
+
+	if key.LifetimeSecs > 0 {
+		t := time.Now().Add(time.Duration(key.LifetimeSecs) * time.Second)
+		p.expire = &t
+	}
+
+	r.keys = append(r.keys, p)
+
+	return nil
+}
+
+// Sign returns a signature for the data.
+func (r *keyring) Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error) {
+	return r.SignWithFlags(key, data, 0)
+}
+
+func (r *keyring) SignWithFlags(key ssh.PublicKey, data []byte, flags SignatureFlags) (*ssh.Signature, error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		return nil, errLocked
+	}
+
+	r.expireKeysLocked()
+	wanted := key.Marshal()
+	for _, k := range r.keys {
+		if bytes.Equal(k.signer.PublicKey().Marshal(), wanted) {
+			if flags == 0 {
+				return k.signer.Sign(rand.Reader, data)
+			} else {
+				if algorithmSigner, ok := k.signer.(ssh.AlgorithmSigner); !ok {
+					return nil, fmt.Errorf("agent: signature does not support non-default signature algorithm: %T", k.signer)
+				} else {
+					var algorithm string
+					switch flags {
+					case SignatureFlagRsaSha256:
+						algorithm = ssh.SigAlgoRSASHA2256
+					case SignatureFlagRsaSha512:
+						algorithm = ssh.SigAlgoRSASHA2512
+					default:
+						return nil, fmt.Errorf("agent: unsupported signature flags: %d", flags)
+					}
+					return algorithmSigner.SignWithAlgorithm(rand.Reader, data, algorithm)
+				}
+			}
+		}
+	}
+	return nil, errors.New("not found")
+}
+
+// Signers returns signers for all the known keys.
+func (r *keyring) Signers() ([]ssh.Signer, error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.locked {
+		return nil, errLocked
+	}
+
+	r.expireKeysLocked()
+	s := make([]ssh.Signer, 0, len(r.keys))
+	for _, k := range r.keys {
+		s = append(s, k.signer)
+	}
+	return s, nil
+}
+
+// The keyring does not support any extensions
+func (r *keyring) Extension(extensionType string, contents []byte) ([]byte, error) {
+	return nil, ErrExtensionUnsupported
+}

vendor/golang.org/x/crypto/ssh/agent/keyring_test.go

@@ -0,0 +1,76 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent
+
+import "testing"
+
+func addTestKey(t *testing.T, a Agent, keyName string) {
+	err := a.Add(AddedKey{
+		PrivateKey: testPrivateKeys[keyName],
+		Comment:    keyName,
+	})
+	if err != nil {
+		t.Fatalf("failed to add key %q: %v", keyName, err)
+	}
+}
+
+func removeTestKey(t *testing.T, a Agent, keyName string) {
+	err := a.Remove(testPublicKeys[keyName])
+	if err != nil {
+		t.Fatalf("failed to remove key %q: %v", keyName, err)
+	}
+}
+
+func validateListedKeys(t *testing.T, a Agent, expectedKeys []string) {
+	listedKeys, err := a.List()
+	if err != nil {
+		t.Fatalf("failed to list keys: %v", err)
+		return
+	}
+	actualKeys := make(map[string]bool)
+	for _, key := range listedKeys {
+		actualKeys[key.Comment] = true
+	}
+
+	matchedKeys := make(map[string]bool)
+	for _, expectedKey := range expectedKeys {
+		if !actualKeys[expectedKey] {
+			t.Fatalf("expected key %q, but was not found", expectedKey)
+		} else {
+			matchedKeys[expectedKey] = true
+		}
+	}
+
+	for actualKey := range actualKeys {
+		if !matchedKeys[actualKey] {
+			t.Fatalf("key %q was found, but was not expected", actualKey)
+		}
+	}
+}
+
+func TestKeyringAddingAndRemoving(t *testing.T) {
+	keyNames := []string{"dsa", "ecdsa", "rsa", "user"}
+
+	// add all test private keys
+	k := NewKeyring()
+	for _, keyName := range keyNames {
+		addTestKey(t, k, keyName)
+	}
+	validateListedKeys(t, k, keyNames)
+
+	// remove a key in the middle
+	keyToRemove := keyNames[1]
+	keyNames = append(keyNames[:1], keyNames[2:]...)
+
+	removeTestKey(t, k, keyToRemove)
+	validateListedKeys(t, k, keyNames)
+
+	// remove all keys
+	err := k.RemoveAll()
+	if err != nil {
+		t.Fatalf("failed to remove all keys: %v", err)
+	}
+	validateListedKeys(t, k, []string{})
+}

vendor/golang.org/x/crypto/ssh/agent/server.go

@@ -0,0 +1,567 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent
+
+import (
+	"crypto/dsa"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rsa"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"math/big"
+
+	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/ssh"
+)
+
+// Server wraps an Agent and uses it to implement the agent side of
+// the SSH-agent, wire protocol.
+type server struct {
+	agent Agent
+}
+
+func (s *server) processRequestBytes(reqData []byte) []byte {
+	rep, err := s.processRequest(reqData)
+	if err != nil {
+		if err != errLocked {
+			// TODO(hanwen): provide better logging interface?
+			log.Printf("agent %d: %v", reqData[0], err)
+		}
+		return []byte{agentFailure}
+	}
+
+	if err == nil && rep == nil {
+		return []byte{agentSuccess}
+	}
+
+	return ssh.Marshal(rep)
+}
+
+func marshalKey(k *Key) []byte {
+	var record struct {
+		Blob    []byte
+		Comment string
+	}
+	record.Blob = k.Marshal()
+	record.Comment = k.Comment
+
+	return ssh.Marshal(&record)
+}
+
+// See [PROTOCOL.agent], section 2.5.1.
+const agentV1IdentitiesAnswer = 2
+
+type agentV1IdentityMsg struct {
+	Numkeys uint32 `sshtype:"2"`
+}
+
+type agentRemoveIdentityMsg struct {
+	KeyBlob []byte `sshtype:"18"`
+}
+
+type agentLockMsg struct {
+	Passphrase []byte `sshtype:"22"`
+}
+
+type agentUnlockMsg struct {
+	Passphrase []byte `sshtype:"23"`
+}
+
+func (s *server) processRequest(data []byte) (interface{}, error) {
+	switch data[0] {
+	case agentRequestV1Identities:
+		return &agentV1IdentityMsg{0}, nil
+
+	case agentRemoveAllV1Identities:
+		return nil, nil
+
+	case agentRemoveIdentity:
+		var req agentRemoveIdentityMsg
+		if err := ssh.Unmarshal(data, &req); err != nil {
+			return nil, err
+		}
+
+		var wk wireKey
+		if err := ssh.Unmarshal(req.KeyBlob, &wk); err != nil {
+			return nil, err
+		}
+
+		return nil, s.agent.Remove(&Key{Format: wk.Format, Blob: req.KeyBlob})
+
+	case agentRemoveAllIdentities:
+		return nil, s.agent.RemoveAll()
+
+	case agentLock:
+		var req agentLockMsg
+		if err := ssh.Unmarshal(data, &req); err != nil {
+			return nil, err
+		}
+
+		return nil, s.agent.Lock(req.Passphrase)
+
+	case agentUnlock:
+		var req agentUnlockMsg
+		if err := ssh.Unmarshal(data, &req); err != nil {
+			return nil, err
+		}
+		return nil, s.agent.Unlock(req.Passphrase)
+
+	case agentSignRequest:
+		var req signRequestAgentMsg
+		if err := ssh.Unmarshal(data, &req); err != nil {
+			return nil, err
+		}
+
+		var wk wireKey
+		if err := ssh.Unmarshal(req.KeyBlob, &wk); err != nil {
+			return nil, err
+		}
+
+		k := &Key{
+			Format: wk.Format,
+			Blob:   req.KeyBlob,
+		}
+
+		var sig *ssh.Signature
+		var err error
+		if extendedAgent, ok := s.agent.(ExtendedAgent); ok {
+			sig, err = extendedAgent.SignWithFlags(k, req.Data, SignatureFlags(req.Flags))
+		} else {
+			sig, err = s.agent.Sign(k, req.Data)
+		}
+
+		if err != nil {
+			return nil, err
+		}
+		return &signResponseAgentMsg{SigBlob: ssh.Marshal(sig)}, nil
+
+	case agentRequestIdentities:
+		keys, err := s.agent.List()
+		if err != nil {
+			return nil, err
+		}
+
+		rep := identitiesAnswerAgentMsg{
+			NumKeys: uint32(len(keys)),
+		}
+		for _, k := range keys {
+			rep.Keys = append(rep.Keys, marshalKey(k)...)
+		}
+		return rep, nil
+
+	case agentAddIDConstrained, agentAddIdentity:
+		return nil, s.insertIdentity(data)
+
+	case agentExtension:
+		// Return a stub object where the whole contents of the response gets marshaled.
+		var responseStub struct {
+			Rest []byte `ssh:"rest"`
+		}
+
+		if extendedAgent, ok := s.agent.(ExtendedAgent); !ok {
+			// If this agent doesn't implement extensions, [PROTOCOL.agent] section 4.7
+			// requires that we return a standard SSH_AGENT_FAILURE message.
+			responseStub.Rest = []byte{agentFailure}
+		} else {
+			var req extensionAgentMsg
+			if err := ssh.Unmarshal(data, &req); err != nil {
+				return nil, err
+			}
+			res, err := extendedAgent.Extension(req.ExtensionType, req.Contents)
+			if err != nil {
+				// If agent extensions are unsupported, return a standard SSH_AGENT_FAILURE
+				// message as required by [PROTOCOL.agent] section 4.7.
+				if err == ErrExtensionUnsupported {
+					responseStub.Rest = []byte{agentFailure}
+				} else {
+					// As the result of any other error processing an extension request,
+					// [PROTOCOL.agent] section 4.7 requires that we return a
+					// SSH_AGENT_EXTENSION_FAILURE code.
+					responseStub.Rest = []byte{agentExtensionFailure}
+				}
+			} else {
+				if len(res) == 0 {
+					return nil, nil
+				}
+				responseStub.Rest = res
+			}
+		}
+
+		return responseStub, nil
+	}
+
+	return nil, fmt.Errorf("unknown opcode %d", data[0])
+}
+
+func parseConstraints(constraints []byte) (lifetimeSecs uint32, confirmBeforeUse bool, extensions []ConstraintExtension, err error) {
+	for len(constraints) != 0 {
+		switch constraints[0] {
+		case agentConstrainLifetime:
+			lifetimeSecs = binary.BigEndian.Uint32(constraints[1:5])
+			constraints = constraints[5:]
+		case agentConstrainConfirm:
+			confirmBeforeUse = true
+			constraints = constraints[1:]
+		case agentConstrainExtension:
+			var msg constrainExtensionAgentMsg
+			if err = ssh.Unmarshal(constraints, &msg); err != nil {
+				return 0, false, nil, err
+			}
+			extensions = append(extensions, ConstraintExtension{
+				ExtensionName:    msg.ExtensionName,
+				ExtensionDetails: msg.ExtensionDetails,
+			})
+			constraints = msg.Rest
+		default:
+			return 0, false, nil, fmt.Errorf("unknown constraint type: %d", constraints[0])
+		}
+	}
+	return
+}
+
+func setConstraints(key *AddedKey, constraintBytes []byte) error {
+	lifetimeSecs, confirmBeforeUse, constraintExtensions, err := parseConstraints(constraintBytes)
+	if err != nil {
+		return err
+	}
+
+	key.LifetimeSecs = lifetimeSecs
+	key.ConfirmBeforeUse = confirmBeforeUse
+	key.ConstraintExtensions = constraintExtensions
+	return nil
+}
+
+func parseRSAKey(req []byte) (*AddedKey, error) {
+	var k rsaKeyMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+	if k.E.BitLen() > 30 {
+		return nil, errors.New("agent: RSA public exponent too large")
+	}
+	priv := &rsa.PrivateKey{
+		PublicKey: rsa.PublicKey{
+			E: int(k.E.Int64()),
+			N: k.N,
+		},
+		D:      k.D,
+		Primes: []*big.Int{k.P, k.Q},
+	}
+	priv.Precompute()
+
+	addedKey := &AddedKey{PrivateKey: priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func parseEd25519Key(req []byte) (*AddedKey, error) {
+	var k ed25519KeyMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+	priv := ed25519.PrivateKey(k.Priv)
+
+	addedKey := &AddedKey{PrivateKey: &priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func parseDSAKey(req []byte) (*AddedKey, error) {
+	var k dsaKeyMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+	priv := &dsa.PrivateKey{
+		PublicKey: dsa.PublicKey{
+			Parameters: dsa.Parameters{
+				P: k.P,
+				Q: k.Q,
+				G: k.G,
+			},
+			Y: k.Y,
+		},
+		X: k.X,
+	}
+
+	addedKey := &AddedKey{PrivateKey: priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func unmarshalECDSA(curveName string, keyBytes []byte, privScalar *big.Int) (priv *ecdsa.PrivateKey, err error) {
+	priv = &ecdsa.PrivateKey{
+		D: privScalar,
+	}
+
+	switch curveName {
+	case "nistp256":
+		priv.Curve = elliptic.P256()
+	case "nistp384":
+		priv.Curve = elliptic.P384()
+	case "nistp521":
+		priv.Curve = elliptic.P521()
+	default:
+		return nil, fmt.Errorf("agent: unknown curve %q", curveName)
+	}
+
+	priv.X, priv.Y = elliptic.Unmarshal(priv.Curve, keyBytes)
+	if priv.X == nil || priv.Y == nil {
+		return nil, errors.New("agent: point not on curve")
+	}
+
+	return priv, nil
+}
+
+func parseEd25519Cert(req []byte) (*AddedKey, error) {
+	var k ed25519CertMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+	pubKey, err := ssh.ParsePublicKey(k.CertBytes)
+	if err != nil {
+		return nil, err
+	}
+	priv := ed25519.PrivateKey(k.Priv)
+	cert, ok := pubKey.(*ssh.Certificate)
+	if !ok {
+		return nil, errors.New("agent: bad ED25519 certificate")
+	}
+
+	addedKey := &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func parseECDSAKey(req []byte) (*AddedKey, error) {
+	var k ecdsaKeyMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+
+	priv, err := unmarshalECDSA(k.Curve, k.KeyBytes, k.D)
+	if err != nil {
+		return nil, err
+	}
+
+	addedKey := &AddedKey{PrivateKey: priv, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func parseRSACert(req []byte) (*AddedKey, error) {
+	var k rsaCertMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+
+	pubKey, err := ssh.ParsePublicKey(k.CertBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	cert, ok := pubKey.(*ssh.Certificate)
+	if !ok {
+		return nil, errors.New("agent: bad RSA certificate")
+	}
+
+	// An RSA publickey as marshaled by rsaPublicKey.Marshal() in keys.go
+	var rsaPub struct {
+		Name string
+		E    *big.Int
+		N    *big.Int
+	}
+	if err := ssh.Unmarshal(cert.Key.Marshal(), &rsaPub); err != nil {
+		return nil, fmt.Errorf("agent: Unmarshal failed to parse public key: %v", err)
+	}
+
+	if rsaPub.E.BitLen() > 30 {
+		return nil, errors.New("agent: RSA public exponent too large")
+	}
+
+	priv := rsa.PrivateKey{
+		PublicKey: rsa.PublicKey{
+			E: int(rsaPub.E.Int64()),
+			N: rsaPub.N,
+		},
+		D:      k.D,
+		Primes: []*big.Int{k.Q, k.P},
+	}
+	priv.Precompute()
+
+	addedKey := &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func parseDSACert(req []byte) (*AddedKey, error) {
+	var k dsaCertMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+	pubKey, err := ssh.ParsePublicKey(k.CertBytes)
+	if err != nil {
+		return nil, err
+	}
+	cert, ok := pubKey.(*ssh.Certificate)
+	if !ok {
+		return nil, errors.New("agent: bad DSA certificate")
+	}
+
+	// A DSA publickey as marshaled by dsaPublicKey.Marshal() in keys.go
+	var w struct {
+		Name       string
+		P, Q, G, Y *big.Int
+	}
+	if err := ssh.Unmarshal(cert.Key.Marshal(), &w); err != nil {
+		return nil, fmt.Errorf("agent: Unmarshal failed to parse public key: %v", err)
+	}
+
+	priv := &dsa.PrivateKey{
+		PublicKey: dsa.PublicKey{
+			Parameters: dsa.Parameters{
+				P: w.P,
+				Q: w.Q,
+				G: w.G,
+			},
+			Y: w.Y,
+		},
+		X: k.X,
+	}
+
+	addedKey := &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func parseECDSACert(req []byte) (*AddedKey, error) {
+	var k ecdsaCertMsg
+	if err := ssh.Unmarshal(req, &k); err != nil {
+		return nil, err
+	}
+
+	pubKey, err := ssh.ParsePublicKey(k.CertBytes)
+	if err != nil {
+		return nil, err
+	}
+	cert, ok := pubKey.(*ssh.Certificate)
+	if !ok {
+		return nil, errors.New("agent: bad ECDSA certificate")
+	}
+
+	// An ECDSA publickey as marshaled by ecdsaPublicKey.Marshal() in keys.go
+	var ecdsaPub struct {
+		Name string
+		ID   string
+		Key  []byte
+	}
+	if err := ssh.Unmarshal(cert.Key.Marshal(), &ecdsaPub); err != nil {
+		return nil, err
+	}
+
+	priv, err := unmarshalECDSA(ecdsaPub.ID, ecdsaPub.Key, k.D)
+	if err != nil {
+		return nil, err
+	}
+
+	addedKey := &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}
+	if err := setConstraints(addedKey, k.Constraints); err != nil {
+		return nil, err
+	}
+	return addedKey, nil
+}
+
+func (s *server) insertIdentity(req []byte) error {
+	var record struct {
+		Type string `sshtype:"17|25"`
+		Rest []byte `ssh:"rest"`
+	}
+
+	if err := ssh.Unmarshal(req, &record); err != nil {
+		return err
+	}
+
+	var addedKey *AddedKey
+	var err error
+
+	switch record.Type {
+	case ssh.KeyAlgoRSA:
+		addedKey, err = parseRSAKey(req)
+	case ssh.KeyAlgoDSA:
+		addedKey, err = parseDSAKey(req)
+	case ssh.KeyAlgoECDSA256, ssh.KeyAlgoECDSA384, ssh.KeyAlgoECDSA521:
+		addedKey, err = parseECDSAKey(req)
+	case ssh.KeyAlgoED25519:
+		addedKey, err = parseEd25519Key(req)
+	case ssh.CertAlgoRSAv01:
+		addedKey, err = parseRSACert(req)
+	case ssh.CertAlgoDSAv01:
+		addedKey, err = parseDSACert(req)
+	case ssh.CertAlgoECDSA256v01, ssh.CertAlgoECDSA384v01, ssh.CertAlgoECDSA521v01:
+		addedKey, err = parseECDSACert(req)
+	case ssh.CertAlgoED25519v01:
+		addedKey, err = parseEd25519Cert(req)
+	default:
+		return fmt.Errorf("agent: not implemented: %q", record.Type)
+	}
+
+	if err != nil {
+		return err
+	}
+	return s.agent.Add(*addedKey)
+}
+
+// ServeAgent serves the agent protocol on the given connection. It
+// returns when an I/O error occurs.
+func ServeAgent(agent Agent, c io.ReadWriter) error {
+	s := &server{agent}
+
+	var length [4]byte
+	for {
+		if _, err := io.ReadFull(c, length[:]); err != nil {
+			return err
+		}
+		l := binary.BigEndian.Uint32(length[:])
+		if l > maxAgentResponseBytes {
+			// We also cap requests.
+			return fmt.Errorf("agent: request too large: %d", l)
+		}
+
+		req := make([]byte, l)
+		if _, err := io.ReadFull(c, req); err != nil {
+			return err
+		}
+
+		repData := s.processRequestBytes(req)
+		if len(repData) > maxAgentResponseBytes {
+			return fmt.Errorf("agent: reply too large: %d bytes", len(repData))
+		}
+
+		binary.BigEndian.PutUint32(length[:], uint32(len(repData)))
+		if _, err := c.Write(length[:]); err != nil {
+			return err
+		}
+		if _, err := c.Write(repData); err != nil {
+			return err
+		}
+	}
+}

vendor/golang.org/x/crypto/ssh/agent/server_test.go

@@ -0,0 +1,259 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package agent
+
+import (
+	"crypto"
+	"crypto/rand"
+	"fmt"
+	pseudorand "math/rand"
+	"reflect"
+	"strings"
+	"testing"
+
+	"golang.org/x/crypto/ssh"
+)
+
+func TestServer(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+	client := NewClient(c1)
+
+	go ServeAgent(NewKeyring(), c2)
+
+	testAgentInterface(t, client, testPrivateKeys["rsa"], nil, 0)
+}
+
+func TestLockServer(t *testing.T) {
+	testLockAgent(NewKeyring(), t)
+}
+
+func TestSetupForwardAgent(t *testing.T) {
+	a, b, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+
+	defer a.Close()
+	defer b.Close()
+
+	_, socket, cleanup := startOpenSSHAgent(t)
+	defer cleanup()
+
+	serverConf := ssh.ServerConfig{
+		NoClientAuth: true,
+	}
+	serverConf.AddHostKey(testSigners["rsa"])
+	incoming := make(chan *ssh.ServerConn, 1)
+	go func() {
+		conn, _, _, err := ssh.NewServerConn(a, &serverConf)
+		if err != nil {
+			t.Fatalf("Server: %v", err)
+		}
+		incoming <- conn
+	}()
+
+	conf := ssh.ClientConfig{
+		HostKeyCallback: ssh.InsecureIgnoreHostKey(),
+	}
+	conn, chans, reqs, err := ssh.NewClientConn(b, "", &conf)
+	if err != nil {
+		t.Fatalf("NewClientConn: %v", err)
+	}
+	client := ssh.NewClient(conn, chans, reqs)
+
+	if err := ForwardToRemote(client, socket); err != nil {
+		t.Fatalf("SetupForwardAgent: %v", err)
+	}
+
+	server := <-incoming
+	ch, reqs, err := server.OpenChannel(channelType, nil)
+	if err != nil {
+		t.Fatalf("OpenChannel(%q): %v", channelType, err)
+	}
+	go ssh.DiscardRequests(reqs)
+
+	agentClient := NewClient(ch)
+	testAgentInterface(t, agentClient, testPrivateKeys["rsa"], nil, 0)
+	conn.Close()
+}
+
+func TestV1ProtocolMessages(t *testing.T) {
+	c1, c2, err := netPipe()
+	if err != nil {
+		t.Fatalf("netPipe: %v", err)
+	}
+	defer c1.Close()
+	defer c2.Close()
+	c := NewClient(c1)
+
+	go ServeAgent(NewKeyring(), c2)
+
+	testV1ProtocolMessages(t, c.(*client))
+}
+
+func testV1ProtocolMessages(t *testing.T, c *client) {
+	reply, err := c.call([]byte{agentRequestV1Identities})
+	if err != nil {
+		t.Fatalf("v1 request all failed: %v", err)
+	}
+	if msg, ok := reply.(*agentV1IdentityMsg); !ok || msg.Numkeys != 0 {
+		t.Fatalf("invalid request all response: %#v", reply)
+	}
+
+	reply, err = c.call([]byte{agentRemoveAllV1Identities})
+	if err != nil {
+		t.Fatalf("v1 remove all failed: %v", err)
+	}
+	if _, ok := reply.(*successAgentMsg); !ok {
+		t.Fatalf("invalid remove all response: %#v", reply)
+	}
+}
+
+func verifyKey(sshAgent Agent) error {
+	keys, err := sshAgent.List()
+	if err != nil {
+		return fmt.Errorf("listing keys: %v", err)
+	}
+
+	if len(keys) != 1 {
+		return fmt.Errorf("bad number of keys found. expected 1, got %d", len(keys))
+	}
+
+	buf := make([]byte, 128)
+	if _, err := rand.Read(buf); err != nil {
+		return fmt.Errorf("rand: %v", err)
+	}
+
+	sig, err := sshAgent.Sign(keys[0], buf)
+	if err != nil {
+		return fmt.Errorf("sign: %v", err)
+	}
+
+	if err := keys[0].Verify(buf, sig); err != nil {
+		return fmt.Errorf("verify: %v", err)
+	}
+	return nil
+}
+
+func addKeyToAgent(key crypto.PrivateKey) error {
+	sshAgent := NewKeyring()
+	if err := sshAgent.Add(AddedKey{PrivateKey: key}); err != nil {
+		return fmt.Errorf("add: %v", err)
+	}
+	return verifyKey(sshAgent)
+}
+
+func TestKeyTypes(t *testing.T) {
+	for k, v := range testPrivateKeys {
+		if err := addKeyToAgent(v); err != nil {
+			t.Errorf("error adding key type %s, %v", k, err)
+		}
+		if err := addCertToAgentSock(v, nil); err != nil {
+			t.Errorf("error adding key type %s, %v", k, err)
+		}
+	}
+}
+
+func addCertToAgentSock(key crypto.PrivateKey, cert *ssh.Certificate) error {
+	a, b, err := netPipe()
+	if err != nil {
+		return err
+	}
+	agentServer := NewKeyring()
+	go ServeAgent(agentServer, a)
+
+	agentClient := NewClient(b)
+	if err := agentClient.Add(AddedKey{PrivateKey: key, Certificate: cert}); err != nil {
+		return fmt.Errorf("add: %v", err)
+	}
+	return verifyKey(agentClient)
+}
+
+func addCertToAgent(key crypto.PrivateKey, cert *ssh.Certificate) error {
+	sshAgent := NewKeyring()
+	if err := sshAgent.Add(AddedKey{PrivateKey: key, Certificate: cert}); err != nil {
+		return fmt.Errorf("add: %v", err)
+	}
+	return verifyKey(sshAgent)
+}
+
+func TestCertTypes(t *testing.T) {
+	for keyType, key := range testPublicKeys {
+		cert := &ssh.Certificate{
+			ValidPrincipals: []string{"gopher1"},
+			ValidAfter:      0,
+			ValidBefore:     ssh.CertTimeInfinity,
+			Key:             key,
+			Serial:          1,
+			CertType:        ssh.UserCert,
+			SignatureKey:    testPublicKeys["rsa"],
+			Permissions: ssh.Permissions{
+				CriticalOptions: map[string]string{},
+				Extensions:      map[string]string{},
+			},
+		}
+		if err := cert.SignCert(rand.Reader, testSigners["rsa"]); err != nil {
+			t.Fatalf("signcert: %v", err)
+		}
+		if err := addCertToAgent(testPrivateKeys[keyType], cert); err != nil {
+			t.Fatalf("%v", err)
+		}
+		if err := addCertToAgentSock(testPrivateKeys[keyType], cert); err != nil {
+			t.Fatalf("%v", err)
+		}
+	}
+}
+
+func TestParseConstraints(t *testing.T) {
+	// Test LifetimeSecs
+	var msg = constrainLifetimeAgentMsg{pseudorand.Uint32()}
+	lifetimeSecs, _, _, err := parseConstraints(ssh.Marshal(msg))
+	if err != nil {
+		t.Fatalf("parseConstraints: %v", err)
+	}
+	if lifetimeSecs != msg.LifetimeSecs {
+		t.Errorf("got lifetime %v, want %v", lifetimeSecs, msg.LifetimeSecs)
+	}
+
+	// Test ConfirmBeforeUse
+	_, confirmBeforeUse, _, err := parseConstraints([]byte{agentConstrainConfirm})
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	if !confirmBeforeUse {
+		t.Error("got comfirmBeforeUse == false")
+	}
+
+	// Test ConstraintExtensions
+	var data []byte
+	var expect []ConstraintExtension
+	for i := 0; i < 10; i++ {
+		var ext = ConstraintExtension{
+			ExtensionName:    fmt.Sprintf("name%d", i),
+			ExtensionDetails: []byte(fmt.Sprintf("details: %d", i)),
+		}
+		expect = append(expect, ext)
+		data = append(data, agentConstrainExtension)
+		data = append(data, ssh.Marshal(ext)...)
+	}
+	_, _, extensions, err := parseConstraints(data)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	if !reflect.DeepEqual(expect, extensions) {
+		t.Errorf("got extension %v, want %v", extensions, expect)
+	}
+
+	// Test Unknown Constraint
+	_, _, _, err = parseConstraints([]byte{128})
+	if err == nil || !strings.Contains(err.Error(), "unknown constraint") {
+		t.Errorf("unexpected error: %v", err)
+	}
+}

vendor/golang.org/x/crypto/ssh/agent/testdata_test.go

@@ -0,0 +1,64 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// IMPLEMENTATION NOTE: To avoid a package loop, this file is in three places:
+// ssh/, ssh/agent, and ssh/test/. It should be kept in sync across all three
+// instances.
+
+package agent
+
+import (
+	"crypto/rand"
+	"fmt"
+
+	"golang.org/x/crypto/ssh"
+	"golang.org/x/crypto/ssh/testdata"
+)
+
+var (
+	testPrivateKeys map[string]interface{}
+	testSigners     map[string]ssh.Signer
+	testPublicKeys  map[string]ssh.PublicKey
+)
+
+func init() {
+	var err error
+
+	n := len(testdata.PEMBytes)
+	testPrivateKeys = make(map[string]interface{}, n)
+	testSigners = make(map[string]ssh.Signer, n)
+	testPublicKeys = make(map[string]ssh.PublicKey, n)
+	for t, k := range testdata.PEMBytes {
+		testPrivateKeys[t], err = ssh.ParseRawPrivateKey(k)
+		if err != nil {
+			panic(fmt.Sprintf("Unable to parse test key %s: %v", t, err))
+		}
+		testSigners[t], err = ssh.NewSignerFromKey(testPrivateKeys[t])
+		if err != nil {
+			panic(fmt.Sprintf("Unable to create signer for test key %s: %v", t, err))
+		}
+		testPublicKeys[t] = testSigners[t].PublicKey()
+	}
+
+	// Create a cert and sign it for use in tests.
+	testCert := &ssh.Certificate{
+		Nonce:           []byte{},                       // To pass reflect.DeepEqual after marshal & parse, this must be non-nil
+		ValidPrincipals: []string{"gopher1", "gopher2"}, // increases test coverage
+		ValidAfter:      0,                              // unix epoch
+		ValidBefore:     ssh.CertTimeInfinity,           // The end of currently representable time.
+		Reserved:        []byte{},                       // To pass reflect.DeepEqual after marshal & parse, this must be non-nil
+		Key:             testPublicKeys["ecdsa"],
+		SignatureKey:    testPublicKeys["rsa"],
+		Permissions: ssh.Permissions{
+			CriticalOptions: map[string]string{},
+			Extensions:      map[string]string{},
+		},
+	}
+	testCert.SignCert(rand.Reader, testSigners["rsa"])
+	testPrivateKeys["cert"] = testPrivateKeys["ecdsa"]
+	testSigners["cert"], err = ssh.NewCertSigner(testCert, testSigners["ecdsa"])
+	if err != nil {
+		panic(fmt.Sprintf("Unable to create certificate signer: %v", err))
+	}
+}