ulreq: adds encoder and decoder for upload-request messages (#106)

* ulreq: adds encoder and decoder for upload-request messages

* ulreq: stop using _test suffix for testing package names (@mcuadros comment)

Author: alcortesm

clients/ssh/git_upload_pack.go

@@ -10,6 +10,8 @@ import (
 
 	"gopkg.in/src-d/go-git.v4/clients/common"
 	"gopkg.in/src-d/go-git.v4/formats/packp/advrefs"
+	"gopkg.in/src-d/go-git.v4/formats/packp/pktline"
+	"gopkg.in/src-d/go-git.v4/formats/packp/ulreq"
 
 	"golang.org/x/crypto/ssh"
 )
@@ -24,7 +26,8 @@ var (
 	ErrUnsupportedVCS         = errors.New("only git is supported")
 	ErrUnsupportedRepo        = errors.New("only github.com is supported")
 
-	nak = []byte("0008NAK\n")
+	nak = []byte("NAK")
+	eol = []byte("\n")
 )
 
 // GitUploadPackService holds the service information.
@@ -139,75 +142,145 @@ func (s *GitUploadPackService) Disconnect() (err error) {
 // 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(r *common.GitUploadPackRequest) (rc io.ReadCloser, err error) {
+func (s *GitUploadPackService) Fetch(req *common.GitUploadPackRequest) (rc io.ReadCloser, err error) {
 	if !s.connected {
 		return nil, ErrNotConnected
 	}
 
-	session, err := s.client.NewSession()
+	session, i, o, done, err := openSSHSession(s.client, s.getCommand())
 	if err != nil {
 		return nil, fmt.Errorf("cannot open SSH session: %s", err)
 	}
 
-	si, err := session.StdinPipe()
+	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, fmt.Errorf("cannot pipe remote stdin: %s", err)
+		return nil, nil, nil, nil, fmt.Errorf("cannot open SSH session: %s", err)
 	}
 
-	so, err := session.StdoutPipe()
+	i, err := session.StdinPipe()
 	if err != nil {
-		return nil, fmt.Errorf("cannot pipe remote stdout: %s", err)
+		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(s.getCommand())
+		done <- session.Run(cmd)
 	}()
 
-	if err := skipAdvRef(so); err != nil {
-		return nil, fmt.Errorf("skipping advertised-refs: %s", err)
+	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)
 	}
 
-	// send the upload request
-	_, err = io.Copy(si, r.Reader())
-	if err != nil {
-		return nil, fmt.Errorf("sending upload-req message: %s", err)
+	if err := sendUlReq(w, req); err != nil {
+		return fmt.Errorf("sending upload-req message: %s", err)
 	}
 
-	if err := si.Close(); err != nil {
-		return nil, fmt.Errorf("closing input: %s", err)
+	if err := sendHaves(w, req); err != nil {
+		return fmt.Errorf("sending haves message: %s", err)
 	}
 
-	// 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
-	buf := make([]byte, len(nak))
-	if _, err := io.ReadFull(so, buf); err != nil {
-		return nil, fmt.Errorf("looking for NAK: %s", err)
+	if err := sendDone(w); err != nil {
+		return fmt.Errorf("sending done message: %s", err)
 	}
-	if !bytes.Equal(buf, nak) {
-		return nil, fmt.Errorf("NAK answer not found")
+
+	if err := w.Close(); err != nil {
+		return fmt.Errorf("closing input: %s", err)
 	}
 
-	return &fetchSession{
-		Reader:  so,
-		session: session,
-		done:    done,
-	}, nil
+	if err := readNAK(r); err != nil {
+		return fmt.Errorf("reading NAK: %s", err)
+	}
+
+	return nil
 }
 
-func skipAdvRef(so io.Reader) error {
-	d := advrefs.NewDecoder(so)
+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
+	done    <-chan error
 }
 
 // Close closes the session and collects the output state of the remote

clients/ssh/git_upload_pack_test.go

@@ -136,6 +136,9 @@ func (s *RemoteSuite) TestFetchError(c *C) {
 	req := &common.GitUploadPackRequest{}
 	req.Want(core.NewHash("1111111111111111111111111111111111111111"))
 
-	_, err := r.Fetch(req)
+	reader, err := r.Fetch(req)
+	c.Assert(err, IsNil)
+
+	err = reader.Close()
 	c.Assert(err, Not(IsNil))
 }