1 files changed, 490 insertions, 0 deletions
diff --git a/libgo/go/exp/ssh/client.go b/libgo/go/exp/ssh/client.go
new file mode 100644
index 0000000..3311385
--- /dev/null
+++ b/libgo/go/exp/ssh/client.go
@@ -0,0 +1,490 @@
+// 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 (
+	"big"
+	"crypto"
+	"crypto/rand"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"sync"
+)
+
+// clientVersion is the fixed identification string that the client will use.
+var clientVersion = []byte("SSH-2.0-Go\r\n")
+
+// ClientConn represents the client side of an SSH connection.
+type ClientConn struct {
+	*transport
+	config *ClientConfig
+	chanlist
+}
+
+// Client returns a new SSH client connection using c as the underlying transport.
+func Client(c net.Conn, config *ClientConfig) (*ClientConn, os.Error) {
+	conn := &ClientConn{
+		transport: newTransport(c, config.rand()),
+		config:    config,
+	}
+	if err := conn.handshake(); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	if err := conn.authenticate(); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	go conn.mainLoop()
+	return conn, nil
+}
+
+// handshake performs the client side key exchange. See RFC 4253 Section 7.
+func (c *ClientConn) handshake() os.Error {
+	var magics handshakeMagics
+
+	if _, err := c.Write(clientVersion); err != nil {
+		return err
+	}
+	if err := c.Flush(); err != nil {
+		return err
+	}
+	magics.clientVersion = clientVersion[:len(clientVersion)-2]
+
+	// read remote server version
+	version, err := readVersion(c)
+	if err != nil {
+		return err
+	}
+	magics.serverVersion = version
+	clientKexInit := kexInitMsg{
+		KexAlgos:                supportedKexAlgos,
+		ServerHostKeyAlgos:      supportedHostKeyAlgos,
+		CiphersClientServer:     supportedCiphers,
+		CiphersServerClient:     supportedCiphers,
+		MACsClientServer:        supportedMACs,
+		MACsServerClient:        supportedMACs,
+		CompressionClientServer: supportedCompressions,
+		CompressionServerClient: supportedCompressions,
+	}
+	kexInitPacket := marshal(msgKexInit, clientKexInit)
+	magics.clientKexInit = kexInitPacket
+
+	if err := c.writePacket(kexInitPacket); err != nil {
+		return err
+	}
+	packet, err := c.readPacket()
+	if err != nil {
+		return err
+	}
+
+	magics.serverKexInit = packet
+
+	var serverKexInit kexInitMsg
+	if err = unmarshal(&serverKexInit, packet, msgKexInit); err != nil {
+		return err
+	}
+
+	kexAlgo, hostKeyAlgo, ok := findAgreedAlgorithms(c.transport, &clientKexInit, &serverKexInit)
+	if !ok {
+		return os.NewError("ssh: no common algorithms")
+	}
+
+	if serverKexInit.FirstKexFollows && kexAlgo != serverKexInit.KexAlgos[0] {
+		// The server sent a Kex message for the wrong algorithm,
+		// which we have to ignore.
+		if _, err := c.readPacket(); err != nil {
+			return err
+		}
+	}
+
+	var H, K []byte
+	var hashFunc crypto.Hash
+	switch kexAlgo {
+	case kexAlgoDH14SHA1:
+		hashFunc = crypto.SHA1
+		dhGroup14Once.Do(initDHGroup14)
+		H, K, err = c.kexDH(dhGroup14, hashFunc, &magics, hostKeyAlgo)
+	default:
+		err = fmt.Errorf("ssh: unexpected key exchange algorithm %v", kexAlgo)
+	}
+	if err != nil {
+		return err
+	}
+
+	if err = c.writePacket([]byte{msgNewKeys}); err != nil {
+		return err
+	}
+	if err = c.transport.writer.setupKeys(clientKeys, K, H, H, hashFunc); err != nil {
+		return err
+	}
+	if packet, err = c.readPacket(); err != nil {
+		return err
+	}
+	if packet[0] != msgNewKeys {
+		return UnexpectedMessageError{msgNewKeys, packet[0]}
+	}
+	return c.transport.reader.setupKeys(serverKeys, K, H, H, hashFunc)
+}
+
+// authenticate authenticates with the remote server. See RFC 4252. 
+// Only "password" authentication is supported.
+func (c *ClientConn) authenticate() os.Error {
+	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
+	}
+
+	// TODO(dfc) support proper authentication method negotation
+	method := "none"
+	if c.config.Password != "" {
+		method = "password"
+	}
+	if err := c.sendUserAuthReq(method); err != nil {
+		return err
+	}
+
+	if packet, err = c.readPacket(); err != nil {
+		return err
+	}
+
+	if packet[0] != msgUserAuthSuccess {
+		return UnexpectedMessageError{msgUserAuthSuccess, packet[0]}
+	}
+	return nil
+}
+
+func (c *ClientConn) sendUserAuthReq(method string) os.Error {
+	length := stringLength([]byte(c.config.Password)) + 1
+	payload := make([]byte, length)
+	// always false for password auth, see RFC 4252 Section 8.
+	payload[0] = 0
+	marshalString(payload[1:], []byte(c.config.Password))
+
+	return c.writePacket(marshal(msgUserAuthRequest, userAuthRequestMsg{
+		User:    c.config.User,
+		Service: serviceSSH,
+		Method:  method,
+		Payload: payload,
+	}))
+}
+
+// kexDH performs Diffie-Hellman key agreement on a ClientConn. The
+// returned values are given the same names as in RFC 4253, section 8.
+func (c *ClientConn) kexDH(group *dhGroup, hashFunc crypto.Hash, magics *handshakeMagics, hostKeyAlgo string) ([]byte, []byte, os.Error) {
+	x, err := rand.Int(c.config.rand(), group.p)
+	if err != nil {
+		return nil, nil, err
+	}
+	X := new(big.Int).Exp(group.g, x, group.p)
+	kexDHInit := kexDHInitMsg{
+		X: X,
+	}
+	if err := c.writePacket(marshal(msgKexDHInit, kexDHInit)); err != nil {
+		return nil, nil, err
+	}
+
+	packet, err := c.readPacket()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var kexDHReply = new(kexDHReplyMsg)
+	if err = unmarshal(kexDHReply, packet, msgKexDHReply); err != nil {
+		return nil, nil, err
+	}
+
+	if kexDHReply.Y.Sign() == 0 || kexDHReply.Y.Cmp(group.p) >= 0 {
+		return nil, nil, os.NewError("server DH parameter out of bounds")
+	}
+
+	kInt := new(big.Int).Exp(kexDHReply.Y, x, group.p)
+	h := hashFunc.New()
+	writeString(h, magics.clientVersion)
+	writeString(h, magics.serverVersion)
+	writeString(h, magics.clientKexInit)
+	writeString(h, magics.serverKexInit)
+	writeString(h, kexDHReply.HostKey)
+	writeInt(h, X)
+	writeInt(h, kexDHReply.Y)
+	K := make([]byte, intLength(kInt))
+	marshalInt(K, kInt)
+	h.Write(K)
+
+	H := h.Sum()
+
+	return H, K, nil
+}
+
+// openChan opens a new client channel. The most common session type is "session". 
+// The full set of valid session types are listed in RFC 4250 4.9.1.
+func (c *ClientConn) openChan(typ string) (*clientChan, os.Error) {
+	ch := c.newChan(c.transport)
+	if err := c.writePacket(marshal(msgChannelOpen, channelOpenMsg{
+		ChanType:      typ,
+		PeersId:       ch.id,
+		PeersWindow:   1 << 14,
+		MaxPacketSize: 1 << 15, // RFC 4253 6.1
+	})); err != nil {
+		c.chanlist.remove(ch.id)
+		return nil, err
+	}
+	// wait for response
+	switch msg := (<-ch.msg).(type) {
+	case *channelOpenConfirmMsg:
+		ch.peersId = msg.MyId
+	case *channelOpenFailureMsg:
+		c.chanlist.remove(ch.id)
+		return nil, os.NewError(msg.Message)
+	default:
+		c.chanlist.remove(ch.id)
+		return nil, os.NewError("Unexpected packet")
+	}
+	return ch, nil
+}
+
+// mainloop reads incoming messages and routes channel messages
+// to their respective ClientChans.
+func (c *ClientConn) mainLoop() {
+	for {
+		packet, err := c.readPacket()
+		if err != nil {
+			// TODO(dfc) signal the underlying close to all channels
+			c.Close()
+			return
+		}
+		// TODO(dfc) A note on blocking channel use. 
+		// The msg, win, data and dataExt channels of a clientChan can 
+		// cause this loop to block indefinately if the consumer does 
+		// not service them. 
+		switch msg := decode(packet).(type) {
+		case *channelOpenMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *channelOpenConfirmMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *channelOpenFailureMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *channelCloseMsg:
+			ch := c.getChan(msg.PeersId)
+			close(ch.win)
+			close(ch.data)
+			close(ch.dataExt)
+			c.chanlist.remove(msg.PeersId)
+		case *channelEOFMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *channelRequestSuccessMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *channelRequestFailureMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *channelRequestMsg:
+			c.getChan(msg.PeersId).msg <- msg
+		case *windowAdjustMsg:
+			c.getChan(msg.PeersId).win <- int(msg.AdditionalBytes)
+		case *channelData:
+			c.getChan(msg.PeersId).data <- msg.Payload
+		case *channelExtendedData:
+			// RFC 4254 5.2 defines data_type_code 1 to be data destined 
+			// for stderr on interactive sessions. Other data types are
+			// silently discarded.
+			if msg.Datatype == 1 {
+				c.getChan(msg.PeersId).dataExt <- msg.Payload
+			}
+		default:
+			fmt.Printf("mainLoop: unhandled %#v\n", msg)
+		}
+	}
+}
+
+// Dial connects to the given network address using net.Dial and 
+// then initiates a SSH handshake, returning the resulting client connection.
+func Dial(network, addr string, config *ClientConfig) (*ClientConn, os.Error) {
+	conn, err := net.Dial(network, addr)
+	if err != nil {
+		return nil, err
+	}
+	return Client(conn, config)
+}
+
+// A ClientConfig structure is used to configure a ClientConn. After one has 
+// been passed to an SSH function it must not be modified.
+type ClientConfig struct {
+	// Rand provides the source of entropy for key exchange. If Rand is 
+	// nil, the cryptographic random reader in package crypto/rand will 
+	// be used.
+	Rand io.Reader
+
+	// The username to authenticate.
+	User string
+
+	// Used for "password" method authentication.
+	Password string
+}
+
+func (c *ClientConfig) rand() io.Reader {
+	if c.Rand == nil {
+		return rand.Reader
+	}
+	return c.Rand
+}
+
+// A clientChan represents a single RFC 4254 channel that is multiplexed 
+// over a single SSH connection.
+type clientChan struct {
+	packetWriter
+	id, peersId uint32
+	data        chan []byte      // receives the payload of channelData messages
+	dataExt     chan []byte      // receives the payload of channelExtendedData messages
+	win         chan int         // receives window adjustments
+	msg         chan interface{} // incoming messages
+}
+
+func newClientChan(t *transport, id uint32) *clientChan {
+	return &clientChan{
+		packetWriter: t,
+		id:           id,
+		data:         make(chan []byte, 16),
+		dataExt:      make(chan []byte, 16),
+		win:          make(chan int, 16),
+		msg:          make(chan interface{}, 16),
+	}
+}
+
+// Close closes the channel. This does not close the underlying connection.
+func (c *clientChan) Close() os.Error {
+	return c.writePacket(marshal(msgChannelClose, channelCloseMsg{
+		PeersId: c.id,
+	}))
+}
+
+func (c *clientChan) sendChanReq(req channelRequestMsg) os.Error {
+	if err := c.writePacket(marshal(msgChannelRequest, req)); err != nil {
+		return err
+	}
+	msg := <-c.msg
+	if _, ok := msg.(*channelRequestSuccessMsg); ok {
+		return nil
+	}
+	return fmt.Errorf("failed to complete request: %s, %#v", req.Request, msg)
+}
+
+// Thread safe channel list.
+type chanlist struct {
+	// protects concurrent access to chans
+	sync.Mutex
+	// chans are indexed by the local id of the channel, clientChan.id.
+	// The PeersId value of messages received by ClientConn.mainloop is
+	// used to locate the right local clientChan in this slice.
+	chans []*clientChan
+}
+
+// Allocate a new ClientChan with the next avail local id.
+func (c *chanlist) newChan(t *transport) *clientChan {
+	c.Lock()
+	defer c.Unlock()
+	for i := range c.chans {
+		if c.chans[i] == nil {
+			ch := newClientChan(t, uint32(i))
+			c.chans[i] = ch
+			return ch
+		}
+	}
+	i := len(c.chans)
+	ch := newClientChan(t, uint32(i))
+	c.chans = append(c.chans, ch)
+	return ch
+}
+
+func (c *chanlist) getChan(id uint32) *clientChan {
+	c.Lock()
+	defer c.Unlock()
+	return c.chans[int(id)]
+}
+
+func (c *chanlist) remove(id uint32) {
+	c.Lock()
+	defer c.Unlock()
+	c.chans[int(id)] = nil
+}
+
+// A chanWriter represents the stdin of a remote process.
+type chanWriter struct {
+	win          chan int // receives window adjustments
+	id           uint32   // this channel's id
+	rwin         int      // current rwin size
+	packetWriter          // for sending channelDataMsg
+}
+
+// Write writes data to the remote process's standard input.
+func (w *chanWriter) Write(data []byte) (n int, err os.Error) {
+	for {
+		if w.rwin == 0 {
+			win, ok := <-w.win
+			if !ok {
+				return 0, os.EOF
+			}
+			w.rwin += win
+			continue
+		}
+		n = len(data)
+		packet := make([]byte, 0, 9+n)
+		packet = append(packet, msgChannelData,
+			byte(w.id)>>24, byte(w.id)>>16, byte(w.id)>>8, byte(w.id),
+			byte(n)>>24, byte(n)>>16, byte(n)>>8, byte(n))
+		err = w.writePacket(append(packet, data...))
+		w.rwin -= n
+		return
+	}
+	panic("unreachable")
+}
+
+func (w *chanWriter) Close() os.Error {
+	return w.writePacket(marshal(msgChannelEOF, channelEOFMsg{w.id}))
+}
+
+// A chanReader represents stdout or stderr of a remote process.
+type chanReader struct {
+	// TODO(dfc) a fixed size channel may not be the right data structure.
+	// If writes to this channel block, they will block mainLoop, making
+	// it unable to receive new messages from the remote side.
+	data         chan []byte // receives data from remote
+	id           uint32
+	packetWriter // for sending windowAdjustMsg
+	buf          []byte
+}
+
+// Read reads data from the remote process's stdout or stderr.
+func (r *chanReader) Read(data []byte) (int, os.Error) {
+	var ok bool
+	for {
+		if len(r.buf) > 0 {
+			n := copy(data, r.buf)
+			r.buf = r.buf[n:]
+			msg := windowAdjustMsg{
+				PeersId:         r.id,
+				AdditionalBytes: uint32(n),
+			}
+			return n, r.writePacket(marshal(msgChannelWindowAdjust, msg))
+		}
+		r.buf, ok = <-r.data
+		if !ok {
+			return 0, os.EOF
+		}
+	}
+	panic("unreachable")
+}
+
+func (r *chanReader) Close() os.Error {
+	return r.writePacket(marshal(msgChannelEOF, channelEOFMsg{r.id}))
+}