1 files changed, 315 insertions, 0 deletions
diff --git a/plumbing/client/ssh/git_upload_pack.go b/plumbing/client/ssh/git_upload_pack.go
new file mode 100644
index 0000000..e2b73fd
--- /dev/null
+++ b/plumbing/client/ssh/git_upload_pack.go
@@ -0,0 +1,315 @@
+// Package ssh implements a ssh client for go-git.
+package ssh
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/client/common"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/packp/advrefs"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/packp/pktline"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/packp/ulreq"
+
+	"golang.org/x/crypto/ssh"
+)
+
+// New errors introduced by this package.
+var (
+	ErrInvalidAuthMethod      = errors.New("invalid ssh auth method")
+	ErrAuthRequired           = errors.New("cannot connect: auth required")
+	ErrNotConnected           = errors.New("not connected")
+	ErrAlreadyConnected       = errors.New("already connected")
+	ErrUploadPackAnswerFormat = errors.New("git-upload-pack bad answer format")
+	ErrUnsupportedVCS         = errors.New("only git is supported")
+	ErrUnsupportedRepo        = errors.New("only github.com is supported")
+
+	nak = []byte("NAK")
+	eol = []byte("\n")
+)
+
+// GitUploadPackService holds the service information.
+// The zero value is safe to use.
+type GitUploadPackService struct {
+	connected bool
+	endpoint  common.Endpoint
+	client    *ssh.Client
+	auth      AuthMethod
+}
+
+// NewGitUploadPackService initialises a GitUploadPackService,
+func NewGitUploadPackService(endpoint common.Endpoint) common.GitUploadPackService {
+	return &GitUploadPackService{endpoint: endpoint}
+}
+
+// Connect connects to the SSH server, unless a AuthMethod was set with SetAuth
+// method, by default uses an auth method based on PublicKeysCallback, it
+// connects to a SSH agent, using the address stored in the SSH_AUTH_SOCK
+// environment var
+func (s *GitUploadPackService) Connect() error {
+	if s.connected {
+		return ErrAlreadyConnected
+	}
+
+	if err := s.setAuthFromEndpoint(); err != nil {
+		return err
+	}
+
+	var err error
+	s.client, err = ssh.Dial("tcp", s.getHostWithPort(), s.auth.clientConfig())
+	if err != nil {
+		return err
+	}
+
+	s.connected = true
+	return nil
+}
+
+func (s *GitUploadPackService) getHostWithPort() string {
+	host := s.endpoint.Host
+	if strings.Index(s.endpoint.Host, ":") == -1 {
+		host += ":22"
+	}
+
+	return host
+}
+
+func (s *GitUploadPackService) setAuthFromEndpoint() error {
+	var u string
+	if info := s.endpoint.User; info != nil {
+		u = info.Username()
+	}
+
+	var err error
+	s.auth, err = NewSSHAgentAuth(u)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// SetAuth sets the AuthMethod
+func (s *GitUploadPackService) SetAuth(auth common.AuthMethod) error {
+	var ok bool
+	s.auth, ok = auth.(AuthMethod)
+	if !ok {
+		return ErrInvalidAuthMethod
+	}
+
+	return nil
+}
+
+// Info returns the GitUploadPackInfo of the repository. The client must be
+// connected with the repository (using the ConnectWithAuth() method) before
+// using this method.
+func (s *GitUploadPackService) Info() (i *common.GitUploadPackInfo, err error) {
+	if !s.connected {
+		return nil, ErrNotConnected
+	}
+
+	session, err := s.client.NewSession()
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		// the session can be closed by the other endpoint,
+		// therefore we must ignore a close error.
+		_ = session.Close()
+	}()
+
+	out, err := session.Output(s.getCommand())
+	if err != nil {
+		return nil, err
+	}
+
+	i = common.NewGitUploadPackInfo()
+	return i, i.Decode(bytes.NewReader(out))
+}
+
+// Disconnect the SSH client.
+func (s *GitUploadPackService) Disconnect() (err error) {
+	if !s.connected {
+		return ErrNotConnected
+	}
+	s.connected = false
+	return s.client.Close()
+}
+
+// Fetch returns a packfile for a given upload request.  It opens a new
+// SSH session on a connected GitUploadPackService, sends the given
+// upload request to the server and returns a reader for the received
+// packfile.  Closing the returned reader will close the SSH session.
+func (s *GitUploadPackService) Fetch(req *common.GitUploadPackRequest) (rc io.ReadCloser, err error) {
+	if !s.connected {
+		return nil, ErrNotConnected
+	}
+
+	session, i, o, done, err := openSSHSession(s.client, s.getCommand())
+	if err != nil {
+		return nil, fmt.Errorf("cannot open SSH session: %s", err)
+	}
+
+	if err := talkPackProtocol(i, o, req); err != nil {
+		return nil, err
+	}
+
+	return &fetchSession{
+		Reader:  o,
+		session: session,
+		done:    done,
+	}, nil
+}
+
+func openSSHSession(c *ssh.Client, cmd string) (
+	*ssh.Session, io.WriteCloser, io.Reader, <-chan error, error) {
+
+	session, err := c.NewSession()
+	if err != nil {
+		return nil, nil, nil, nil, fmt.Errorf("cannot open SSH session: %s", err)
+	}
+
+	i, err := session.StdinPipe()
+	if err != nil {
+		return nil, nil, nil, nil, fmt.Errorf("cannot pipe remote stdin: %s", err)
+	}
+
+	o, err := session.StdoutPipe()
+	if err != nil {
+		return nil, nil, nil, nil, fmt.Errorf("cannot pipe remote stdout: %s", err)
+	}
+
+	done := make(chan error)
+	go func() {
+		done <- session.Run(cmd)
+	}()
+
+	return session, i, o, done, nil
+}
+
+// TODO support multi_ack mode
+// TODO support multi_ack_detailed mode
+// TODO support acks for common objects
+// TODO build a proper state machine for all these processing options
+func talkPackProtocol(w io.WriteCloser, r io.Reader,
+	req *common.GitUploadPackRequest) error {
+
+	if err := skipAdvRef(r); err != nil {
+		return fmt.Errorf("skipping advertised-refs: %s", err)
+	}
+
+	if err := sendUlReq(w, req); err != nil {
+		return fmt.Errorf("sending upload-req message: %s", err)
+	}
+
+	if err := sendHaves(w, req); err != nil {
+		return fmt.Errorf("sending haves message: %s", err)
+	}
+
+	if err := sendDone(w); err != nil {
+		return fmt.Errorf("sending done message: %s", err)
+	}
+
+	if err := w.Close(); err != nil {
+		return fmt.Errorf("closing input: %s", err)
+	}
+
+	if err := readNAK(r); err != nil {
+		return fmt.Errorf("reading NAK: %s", err)
+	}
+
+	return nil
+}
+
+func skipAdvRef(r io.Reader) error {
+	d := advrefs.NewDecoder(r)
+	ar := advrefs.New()
+
+	return d.Decode(ar)
+}
+
+func sendUlReq(w io.Writer, req *common.GitUploadPackRequest) error {
+	ur := ulreq.New()
+	ur.Wants = req.Wants
+	ur.Depth = ulreq.DepthCommits(req.Depth)
+	e := ulreq.NewEncoder(w)
+
+	return e.Encode(ur)
+}
+
+func sendHaves(w io.Writer, req *common.GitUploadPackRequest) error {
+	e := pktline.NewEncoder(w)
+	for _, have := range req.Haves {
+		if err := e.Encodef("have %s\n", have); err != nil {
+			return fmt.Errorf("sending haves for %q: err ", have, err)
+		}
+	}
+
+	if len(req.Haves) != 0 {
+		if err := e.Flush(); err != nil {
+			return fmt.Errorf("sending flush-pkt after haves: %s", err)
+		}
+	}
+
+	return nil
+}
+
+func sendDone(w io.Writer) error {
+	e := pktline.NewEncoder(w)
+
+	return e.Encodef("done\n")
+}
+
+func readNAK(r io.Reader) error {
+	s := pktline.NewScanner(r)
+	if !s.Scan() {
+		return s.Err()
+	}
+
+	b := s.Bytes()
+	b = bytes.TrimSuffix(b, eol)
+	if !bytes.Equal(b, nak) {
+		return fmt.Errorf("expecting NAK, found %q instead", string(b))
+	}
+
+	return nil
+}
+
+type fetchSession struct {
+	io.Reader
+	session *ssh.Session
+	done    <-chan error
+}
+
+// Close closes the session and collects the output state of the remote
+// SSH command.
+//
+// If both the remote command and the closing of the session completes
+// susccessfully it returns nil.
+//
+// If the remote command completes unsuccessfully or is interrupted by a
+// signal, it returns the corresponding *ExitError.
+//
+// Otherwise, if clossing the SSH session fails it returns the close
+// error.  Closing the session when the other has already close it is
+// not cosidered an error.
+func (f *fetchSession) Close() (err error) {
+	if err := <-f.done; err != nil {
+		return err
+	}
+
+	if err := f.session.Close(); err != nil && err != io.EOF {
+		return err
+	}
+
+	return nil
+}
+
+func (s *GitUploadPackService) getCommand() string {
+	directory := s.endpoint.Path
+	directory = directory[1:]
+
+	return fmt.Sprintf("git-upload-pack '%s'", directory)
+}