go.crypto: initial code

Manual edits to README.
Moved from main Go repository, deleted Makefiles, ran gofix -r go1rename.

Tested with: go test code.google.com/p/go.crypto/...

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5564059

1 files changed, 316 insertions, 0 deletions

diff --git a/ssh/client_auth.go b/ssh/client_auth.go
new file mode 100644
index 0000000..3a7e9fb
--- /dev/null
+++ b/ssh/client_auth.go
@@ -0,0 +1,316 @@
+// Copyright 2011 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 ssh
+
+import (
+	"errors"
+	"io"
+)
+
+// authenticate authenticates with the remote server. See RFC 4252.
+func (c *ClientConn) authenticate(session []byte) error {
+	// initiate user auth session
+	if err := c.writePacket(marshal(msgServiceRequest, serviceRequestMsg{serviceUserAuth})); err != nil {
+		return err
+	}
+	packet, err := c.readPacket()
+	if err != nil {
+		return err
+	}
+	var serviceAccept serviceAcceptMsg
+	if err := unmarshal(&serviceAccept, packet, msgServiceAccept); err != nil {
+		return err
+	}
+	// during the authentication phase the client first attempts the "none" method
+	// then any untried methods suggested by the server.
+	tried, remain := make(map[string]bool), make(map[string]bool)
+	for auth := ClientAuth(new(noneAuth)); auth != nil; {
+		ok, methods, err := auth.auth(session, c.config.User, c.transport, c.config.rand())
+		if err != nil {
+			return err
+		}
+		if ok {
+			// success
+			return nil
+		}
+		tried[auth.method()] = true
+		delete(remain, auth.method())
+		for _, meth := range methods {
+			if tried[meth] {
+				// if we've tried meth already, skip it.
+				continue
+			}
+			remain[meth] = true
+		}
+		auth = nil
+		for _, a := range c.config.Auth {
+			if remain[a.method()] {
+				auth = a
+				break
+			}
+		}
+	}
+	return errors.New("ssh: unable to authenticate, no supported methods remain")
+}
+
+// A ClientAuth represents an instance of an RFC 4252 authentication method.
+type ClientAuth interface {
+	// auth authenticates user over transport t.
+	// Returns true if authentication is successful.
+	// If authentication is not successful, a []string of alternative
+	// method names is returned.
+	auth(session []byte, user string, t *transport, rand io.Reader) (bool, []string, error)
+
+	// method returns the RFC 4252 method name.
+	method() string
+}
+
+// "none" authentication, RFC 4252 section 5.2.
+type noneAuth int
+
+func (n *noneAuth) auth(session []byte, user string, t *transport, rand io.Reader) (bool, []string, error) {
+	if err := t.writePacket(marshal(msgUserAuthRequest, userAuthRequestMsg{
+		User:    user,
+		Service: serviceSSH,
+		Method:  "none",
+	})); err != nil {
+		return false, nil, err
+	}
+
+	return handleAuthResponse(t)
+}
+
+func (n *noneAuth) method() string {
+	return "none"
+}
+
+// "password" authentication, RFC 4252 Section 8.
+type passwordAuth struct {
+	ClientPassword
+}
+
+func (p *passwordAuth) auth(session []byte, user string, t *transport, rand io.Reader) (bool, []string, error) {
+	type passwordAuthMsg struct {
+		User     string
+		Service  string
+		Method   string
+		Reply    bool
+		Password string
+	}
+
+	pw, err := p.Password(user)
+	if err != nil {
+		return false, nil, err
+	}
+
+	if err := t.writePacket(marshal(msgUserAuthRequest, passwordAuthMsg{
+		User:     user,
+		Service:  serviceSSH,
+		Method:   "password",
+		Reply:    false,
+		Password: pw,
+	})); err != nil {
+		return false, nil, err
+	}
+
+	return handleAuthResponse(t)
+}
+
+func (p *passwordAuth) method() string {
+	return "password"
+}
+
+// A ClientPassword implements access to a client's passwords.
+type ClientPassword interface {
+	// Password returns the password to use for user.
+	Password(user string) (password string, err error)
+}
+
+// ClientAuthPassword returns a ClientAuth using password authentication.
+func ClientAuthPassword(impl ClientPassword) ClientAuth {
+	return &passwordAuth{impl}
+}
+
+// ClientKeyring implements access to a client key ring.
+type ClientKeyring interface {
+	// Key returns the i'th rsa.Publickey or dsa.Publickey, or nil if
+	// no key exists at i.
+	Key(i int) (key interface{}, err error)
+
+	// Sign returns a signature of the given data using the i'th key
+	// and the supplied random source.
+	Sign(i int, rand io.Reader, data []byte) (sig []byte, err error)
+}
+
+// "publickey" authentication, RFC 4252 Section 7.
+type publickeyAuth struct {
+	ClientKeyring
+}
+
+type publickeyAuthMsg struct {
+	User    string
+	Service string
+	Method  string
+	// HasSig indicates to the reciver packet that the auth request is signed and
+	// should be used for authentication of the request.
+	HasSig   bool
+	Algoname string
+	Pubkey   string
+	// Sig is defined as []byte so marshal will exclude it during validateKey
+	Sig []byte `ssh:"rest"`
+}
+
+func (p *publickeyAuth) auth(session []byte, user string, t *transport, rand io.Reader) (bool, []string, error) {
+
+	// Authentication is performed in two stages. The first stage sends an
+	// enquiry to test if each key is acceptable to the remote. The second
+	// stage attempts to authenticate with the valid keys obtained in the
+	// first stage.
+
+	var index int
+	// a map of public keys to their index in the keyring
+	validKeys := make(map[int]interface{})
+	for {
+		key, err := p.Key(index)
+		if err != nil {
+			return false, nil, err
+		}
+		if key == nil {
+			// no more keys in the keyring
+			break
+		}
+
+		if ok, err := p.validateKey(key, user, t); ok {
+			validKeys[index] = key
+		} else {
+			if err != nil {
+				return false, nil, err
+			}
+		}
+		index++
+	}
+
+	// methods that may continue if this auth is not successful.
+	var methods []string
+	for i, key := range validKeys {
+		pubkey := serializePublickey(key)
+		algoname := algoName(key)
+		sign, err := p.Sign(i, rand, buildDataSignedForAuth(session, userAuthRequestMsg{
+			User:    user,
+			Service: serviceSSH,
+			Method:  p.method(),
+		}, []byte(algoname), pubkey))
+		if err != nil {
+			return false, nil, err
+		}
+		// manually wrap the serialized signature in a string
+		s := serializeSignature(algoname, sign)
+		sig := make([]byte, stringLength(s))
+		marshalString(sig, s)
+		msg := publickeyAuthMsg{
+			User:     user,
+			Service:  serviceSSH,
+			Method:   p.method(),
+			HasSig:   true,
+			Algoname: algoname,
+			Pubkey:   string(pubkey),
+			Sig:      sig,
+		}
+		p := marshal(msgUserAuthRequest, msg)
+		if err := t.writePacket(p); err != nil {
+			return false, nil, err
+		}
+		success, methods, err := handleAuthResponse(t)
+		if err != nil {
+			return false, nil, err
+		}
+		if success {
+			return success, methods, err
+		}
+	}
+	return false, methods, nil
+}
+
+// validateKey validates the key provided it is acceptable to the server.
+func (p *publickeyAuth) validateKey(key interface{}, user string, t *transport) (bool, error) {
+	pubkey := serializePublickey(key)
+	algoname := algoName(key)
+	msg := publickeyAuthMsg{
+		User:     user,
+		Service:  serviceSSH,
+		Method:   p.method(),
+		HasSig:   false,
+		Algoname: algoname,
+		Pubkey:   string(pubkey),
+	}
+	if err := t.writePacket(marshal(msgUserAuthRequest, msg)); err != nil {
+		return false, err
+	}
+
+	return p.confirmKeyAck(key, t)
+}
+
+func (p *publickeyAuth) confirmKeyAck(key interface{}, t *transport) (bool, error) {
+	pubkey := serializePublickey(key)
+	algoname := algoName(key)
+
+	for {
+		packet, err := t.readPacket()
+		if err != nil {
+			return false, err
+		}
+		switch packet[0] {
+		case msgUserAuthBanner:
+			// TODO(gpaul): add callback to present the banner to the user
+		case msgUserAuthPubKeyOk:
+			msg := decode(packet).(*userAuthPubKeyOkMsg)
+			if msg.Algo != algoname || msg.PubKey != string(pubkey) {
+				return false, nil
+			}
+			return true, nil
+		case msgUserAuthFailure:
+			return false, nil
+		default:
+			return false, UnexpectedMessageError{msgUserAuthSuccess, packet[0]}
+		}
+	}
+	panic("unreachable")
+}
+
+func (p *publickeyAuth) method() string {
+	return "publickey"
+}
+
+// ClientAuthKeyring returns a ClientAuth using public key authentication.
+func ClientAuthKeyring(impl ClientKeyring) ClientAuth {
+	return &publickeyAuth{impl}
+}
+
+// handleAuthResponse returns whether the preceding authentication request succeeded
+// along with a list of remaining authentication methods to try next and
+// an error if an unexpected response was received.
+func handleAuthResponse(t *transport) (bool, []string, error) {
+	for {
+		packet, err := t.readPacket()
+		if err != nil {
+			return false, nil, err
+		}
+
+		switch packet[0] {
+		case msgUserAuthBanner:
+			// TODO: add callback to present the banner to the user
+		case msgUserAuthFailure:
+			msg := decode(packet).(*userAuthFailureMsg)
+			return false, msg.Methods, nil
+		case msgUserAuthSuccess:
+			return true, nil, nil
+		case msgDisconnect:
+			return false, nil, io.EOF
+		default:
+			return false, nil, UnexpectedMessageError{msgUserAuthSuccess, packet[0]}
+		}
+	}
+	panic("unreachable")
+}