1 files changed, 353 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/ssh/transport.go b/vendor/golang.org/x/crypto/ssh/transport.go
new file mode 100644
index 000000000..49ddc2e7d
--- /dev/null
+++ b/vendor/golang.org/x/crypto/ssh/transport.go
@@ -0,0 +1,353 @@
+// 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 (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"log"
+)
+
+// debugTransport if set, will print packet types as they go over the
+// wire. No message decoding is done, to minimize the impact on timing.
+const debugTransport = false
+
+const (
+	gcmCipherID    = "aes128-gcm@openssh.com"
+	aes128cbcID    = "aes128-cbc"
+	tripledescbcID = "3des-cbc"
+)
+
+// packetConn represents a transport that implements packet based
+// operations.
+type packetConn interface {
+	// Encrypt and send a packet of data to the remote peer.
+	writePacket(packet []byte) error
+
+	// Read a packet from the connection. The read is blocking,
+	// i.e. if error is nil, then the returned byte slice is
+	// always non-empty.
+	readPacket() ([]byte, error)
+
+	// Close closes the write-side of the connection.
+	Close() error
+}
+
+// transport is the keyingTransport that implements the SSH packet
+// protocol.
+type transport struct {
+	reader connectionState
+	writer connectionState
+
+	bufReader *bufio.Reader
+	bufWriter *bufio.Writer
+	rand      io.Reader
+	isClient  bool
+	io.Closer
+}
+
+// packetCipher represents a combination of SSH encryption/MAC
+// protocol.  A single instance should be used for one direction only.
+type packetCipher interface {
+	// writeCipherPacket encrypts the packet and writes it to w. The
+	// contents of the packet are generally scrambled.
+	writeCipherPacket(seqnum uint32, w io.Writer, rand io.Reader, packet []byte) error
+
+	// readCipherPacket reads and decrypts a packet of data. The
+	// returned packet may be overwritten by future calls of
+	// readPacket.
+	readCipherPacket(seqnum uint32, r io.Reader) ([]byte, error)
+}
+
+// connectionState represents one side (read or write) of the
+// connection. This is necessary because each direction has its own
+// keys, and can even have its own algorithms
+type connectionState struct {
+	packetCipher
+	seqNum           uint32
+	dir              direction
+	pendingKeyChange chan packetCipher
+}
+
+// prepareKeyChange sets up key material for a keychange. The key changes in
+// both directions are triggered by reading and writing a msgNewKey packet
+// respectively.
+func (t *transport) prepareKeyChange(algs *algorithms, kexResult *kexResult) error {
+	ciph, err := newPacketCipher(t.reader.dir, algs.r, kexResult)
+	if err != nil {
+		return err
+	}
+	t.reader.pendingKeyChange <- ciph
+
+	ciph, err = newPacketCipher(t.writer.dir, algs.w, kexResult)
+	if err != nil {
+		return err
+	}
+	t.writer.pendingKeyChange <- ciph
+
+	return nil
+}
+
+func (t *transport) printPacket(p []byte, write bool) {
+	if len(p) == 0 {
+		return
+	}
+	who := "server"
+	if t.isClient {
+		who = "client"
+	}
+	what := "read"
+	if write {
+		what = "write"
+	}
+
+	log.Println(what, who, p[0])
+}
+
+// Read and decrypt next packet.
+func (t *transport) readPacket() (p []byte, err error) {
+	for {
+		p, err = t.reader.readPacket(t.bufReader)
+		if err != nil {
+			break
+		}
+		if len(p) == 0 || (p[0] != msgIgnore && p[0] != msgDebug) {
+			break
+		}
+	}
+	if debugTransport {
+		t.printPacket(p, false)
+	}
+
+	return p, err
+}
+
+func (s *connectionState) readPacket(r *bufio.Reader) ([]byte, error) {
+	packet, err := s.packetCipher.readCipherPacket(s.seqNum, r)
+	s.seqNum++
+	if err == nil && len(packet) == 0 {
+		err = errors.New("ssh: zero length packet")
+	}
+
+	if len(packet) > 0 {
+		switch packet[0] {
+		case msgNewKeys:
+			select {
+			case cipher := <-s.pendingKeyChange:
+				s.packetCipher = cipher
+			default:
+				return nil, errors.New("ssh: got bogus newkeys message")
+			}
+
+		case msgDisconnect:
+			// Transform a disconnect message into an
+			// error. Since this is lowest level at which
+			// we interpret message types, doing it here
+			// ensures that we don't have to handle it
+			// elsewhere.
+			var msg disconnectMsg
+			if err := Unmarshal(packet, &msg); err != nil {
+				return nil, err
+			}
+			return nil, &msg
+		}
+	}
+
+	// The packet may point to an internal buffer, so copy the
+	// packet out here.
+	fresh := make([]byte, len(packet))
+	copy(fresh, packet)
+
+	return fresh, err
+}
+
+func (t *transport) writePacket(packet []byte) error {
+	if debugTransport {
+		t.printPacket(packet, true)
+	}
+	return t.writer.writePacket(t.bufWriter, t.rand, packet)
+}
+
+func (s *connectionState) writePacket(w *bufio.Writer, rand io.Reader, packet []byte) error {
+	changeKeys := len(packet) > 0 && packet[0] == msgNewKeys
+
+	err := s.packetCipher.writeCipherPacket(s.seqNum, w, rand, packet)
+	if err != nil {
+		return err
+	}
+	if err = w.Flush(); err != nil {
+		return err
+	}
+	s.seqNum++
+	if changeKeys {
+		select {
+		case cipher := <-s.pendingKeyChange:
+			s.packetCipher = cipher
+		default:
+			panic("ssh: no key material for msgNewKeys")
+		}
+	}
+	return err
+}
+
+func newTransport(rwc io.ReadWriteCloser, rand io.Reader, isClient bool) *transport {
+	t := &transport{
+		bufReader: bufio.NewReader(rwc),
+		bufWriter: bufio.NewWriter(rwc),
+		rand:      rand,
+		reader: connectionState{
+			packetCipher:     &streamPacketCipher{cipher: noneCipher{}},
+			pendingKeyChange: make(chan packetCipher, 1),
+		},
+		writer: connectionState{
+			packetCipher:     &streamPacketCipher{cipher: noneCipher{}},
+			pendingKeyChange: make(chan packetCipher, 1),
+		},
+		Closer: rwc,
+	}
+	t.isClient = isClient
+
+	if isClient {
+		t.reader.dir = serverKeys
+		t.writer.dir = clientKeys
+	} else {
+		t.reader.dir = clientKeys
+		t.writer.dir = serverKeys
+	}
+
+	return t
+}
+
+type direction struct {
+	ivTag     []byte
+	keyTag    []byte
+	macKeyTag []byte
+}
+
+var (
+	serverKeys = direction{[]byte{'B'}, []byte{'D'}, []byte{'F'}}
+	clientKeys = direction{[]byte{'A'}, []byte{'C'}, []byte{'E'}}
+)
+
+// setupKeys sets the cipher and MAC keys from kex.K, kex.H and sessionId, as
+// described in RFC 4253, section 6.4. direction should either be serverKeys
+// (to setup server->client keys) or clientKeys (for client->server keys).
+func newPacketCipher(d direction, algs directionAlgorithms, kex *kexResult) (packetCipher, error) {
+	cipherMode := cipherModes[algs.Cipher]
+	macMode := macModes[algs.MAC]
+
+	iv := make([]byte, cipherMode.ivSize)
+	key := make([]byte, cipherMode.keySize)
+	macKey := make([]byte, macMode.keySize)
+
+	generateKeyMaterial(iv, d.ivTag, kex)
+	generateKeyMaterial(key, d.keyTag, kex)
+	generateKeyMaterial(macKey, d.macKeyTag, kex)
+
+	return cipherModes[algs.Cipher].create(key, iv, macKey, algs)
+}
+
+// generateKeyMaterial fills out with key material generated from tag, K, H
+// and sessionId, as specified in RFC 4253, section 7.2.
+func generateKeyMaterial(out, tag []byte, r *kexResult) {
+	var digestsSoFar []byte
+
+	h := r.Hash.New()
+	for len(out) > 0 {
+		h.Reset()
+		h.Write(r.K)
+		h.Write(r.H)
+
+		if len(digestsSoFar) == 0 {
+			h.Write(tag)
+			h.Write(r.SessionID)
+		} else {
+			h.Write(digestsSoFar)
+		}
+
+		digest := h.Sum(nil)
+		n := copy(out, digest)
+		out = out[n:]
+		if len(out) > 0 {
+			digestsSoFar = append(digestsSoFar, digest...)
+		}
+	}
+}
+
+const packageVersion = "SSH-2.0-Go"
+
+// Sends and receives a version line.  The versionLine string should
+// be US ASCII, start with "SSH-2.0-", and should not include a
+// newline. exchangeVersions returns the other side's version line.
+func exchangeVersions(rw io.ReadWriter, versionLine []byte) (them []byte, err error) {
+	// Contrary to the RFC, we do not ignore lines that don't
+	// start with "SSH-2.0-" to make the library usable with
+	// nonconforming servers.
+	for _, c := range versionLine {
+		// The spec disallows non US-ASCII chars, and
+		// specifically forbids null chars.
+		if c < 32 {
+			return nil, errors.New("ssh: junk character in version line")
+		}
+	}
+	if _, err = rw.Write(append(versionLine, '\r', '\n')); err != nil {
+		return
+	}
+
+	them, err = readVersion(rw)
+	return them, err
+}
+
+// maxVersionStringBytes is the maximum number of bytes that we'll
+// accept as a version string. RFC 4253 section 4.2 limits this at 255
+// chars
+const maxVersionStringBytes = 255
+
+// Read version string as specified by RFC 4253, section 4.2.
+func readVersion(r io.Reader) ([]byte, error) {
+	versionString := make([]byte, 0, 64)
+	var ok bool
+	var buf [1]byte
+
+	for length := 0; length < maxVersionStringBytes; length++ {
+		_, err := io.ReadFull(r, buf[:])
+		if err != nil {
+			return nil, err
+		}
+		// The RFC says that the version should be terminated with \r\n
+		// but several SSH servers actually only send a \n.
+		if buf[0] == '\n' {
+			if !bytes.HasPrefix(versionString, []byte("SSH-")) {
+				// RFC 4253 says we need to ignore all version string lines
+				// except the one containing the SSH version (provided that
+				// all the lines do not exceed 255 bytes in total).
+				versionString = versionString[:0]
+				continue
+			}
+			ok = true
+			break
+		}
+
+		// non ASCII chars are disallowed, but we are lenient,
+		// since Go doesn't use null-terminated strings.
+
+		// The RFC allows a comment after a space, however,
+		// all of it (version and comments) goes into the
+		// session hash.
+		versionString = append(versionString, buf[0])
+	}
+
+	if !ok {
+		return nil, errors.New("ssh: overflow reading version string")
+	}
+
+	// There might be a '\r' on the end which we should remove.
+	if len(versionString) > 0 && versionString[len(versionString)-1] == '\r' {
+		versionString = versionString[:len(versionString)-1]
+	}
+	return versionString, nil
+}