libgo: Update to weekly 2011-11-09.

From-SVN: r182073

1 files changed, 157 insertions, 0 deletions

diff --git a/libgo/go/exp/ssh/client_auth.go b/libgo/go/exp/ssh/client_auth.go
new file mode 100644
index 0000000..0089d0c
--- /dev/null
+++ b/libgo/go/exp/ssh/client_auth.go
@@ -0,0 +1,157 @@
+// 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"
+)
+
+// authenticate authenticates with the remote server. See RFC 4252. 
+func (c *ClientConn) authenticate() 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(c.config.User, c.transport)
+		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(user string, t *transport) (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(user string, t *transport) (bool, []string, error) {
+	if err := t.writePacket(marshal(msgUserAuthRequest, userAuthRequestMsg{
+		User:    user,
+		Service: serviceSSH,
+		Method:  "none",
+	})); err != nil {
+		return false, nil, err
+	}
+
+	packet, err := t.readPacket()
+	if err != nil {
+		return false, nil, err
+	}
+
+	switch packet[0] {
+	case msgUserAuthSuccess:
+		return true, nil, nil
+	case msgUserAuthFailure:
+		msg := decode(packet).(*userAuthFailureMsg)
+		return false, msg.Methods, nil
+	}
+	return false, nil, UnexpectedMessageError{msgUserAuthSuccess, packet[0]}
+}
+
+func (n *noneAuth) method() string {
+	return "none"
+}
+
+// "password" authentication, RFC 4252 Section 8.
+type passwordAuth struct {
+	ClientPassword
+}
+
+func (p *passwordAuth) auth(user string, t *transport) (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
+	}
+
+	packet, err := t.readPacket()
+	if err != nil {
+		return false, nil, err
+	}
+
+	switch packet[0] {
+	case msgUserAuthSuccess:
+		return true, nil, nil
+	case msgUserAuthFailure:
+		msg := decode(packet).(*userAuthFailureMsg)
+		return false, msg.Methods, nil
+	}
+	return false, nil, UnexpectedMessageError{msgUserAuthSuccess, packet[0]}
+}
+
+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}
+}