server: add git server implementation (#190)

* server: add generic server implementation (transport-independent),
  both for git-upload-pack and git-receive-pack.
* server: move internal functions to internal/common.
* cli: add git-receive-pack and git-upload-pack implementations.
* format/packfile: add UpdateObjectStorage function, extracted from
  Remote.
* transport: implement tranport RPC-like, only with git-upload-pack and
  git-receive-pack methods. Client renamed to Transport.
* storer: add storer.Storer interface.
* protocol/packp: add UploadPackResponse constructor with packfile.
* protocol/packp: fix UploadPackResponse encoding, add tests.
* protocol/packp/capability: implement All.

2 files changed, 86 insertions, 14 deletions

diff --git a/plumbing/transport/internal/common/common.go b/plumbing/transport/internal/common/common.go
index 17c473e..831c4d7 100644
--- a/plumbing/transport/internal/common/common.go
+++ b/plumbing/transport/internal/common/common.go
@@ -77,20 +77,20 @@ type client struct {
 }
 
 // NewClient creates a new client using the given Commander.
-func NewClient(runner Commander) transport.Client {
+func NewClient(runner Commander) transport.Transport {
 	return &client{runner}
 }
 
-// NewFetchPackSession creates a new FetchPackSession.
-func (c *client) NewFetchPackSession(ep transport.Endpoint) (
-	transport.FetchPackSession, error) {
+// NewUploadPackSession creates a new UploadPackSession.
+func (c *client) NewUploadPackSession(ep transport.Endpoint) (
+	transport.UploadPackSession, error) {
 
 	return c.newSession(transport.UploadPackServiceName, ep)
 }
 
-// NewSendPackSession creates a new SendPackSession.
-func (c *client) NewSendPackSession(ep transport.Endpoint) (
-	transport.SendPackSession, error) {
+// NewReceivePackSession creates a new ReceivePackSession.
+func (c *client) NewReceivePackSession(ep transport.Endpoint) (
+	transport.ReceivePackSession, error) {
 
 	return c.newSession(transport.ReceivePackServiceName, ep)
 }
@@ -219,9 +219,9 @@ func (s *session) handleAdvRefDecodeError(err error) error {
 	return err
 }
 
-// FetchPack performs a request to the server to fetch a packfile. A reader is
+// UploadPack performs a request to the server to fetch a packfile. A reader is
 // returned with the packfile content. The reader must be closed after reading.
-func (s *session) FetchPack(req *packp.UploadPackRequest) (*packp.UploadPackResponse, error) {
+func (s *session) UploadPack(req *packp.UploadPackRequest) (*packp.UploadPackResponse, error) {
 	if req.IsEmpty() {
 		return nil, transport.ErrEmptyUploadPackRequest
 	}
@@ -236,7 +236,7 @@ func (s *session) FetchPack(req *packp.UploadPackRequest) (*packp.UploadPackResp
 
 	s.packRun = true
 
-	if err := fetchPack(s.Stdin, s.Stdout, req); err != nil {
+	if err := uploadPack(s.Stdin, s.Stdout, req); err != nil {
 		return nil, err
 	}
 
@@ -259,7 +259,7 @@ func (s *session) FetchPack(req *packp.UploadPackRequest) (*packp.UploadPackResp
 	return DecodeUploadPackResponse(rc, req)
 }
 
-func (s *session) SendPack(req *packp.ReferenceUpdateRequest) (*packp.ReportStatus, error) {
+func (s *session) ReceivePack(req *packp.ReferenceUpdateRequest) (*packp.ReportStatus, error) {
 	if _, err := s.AdvertisedReferences(); err != nil {
 		return nil, err
 	}
@@ -295,7 +295,7 @@ func (s *session) finish() error {
 
 	s.finished = true
 
-	// If we did not run fetch-pack or send-pack, we close the connection
+	// If we did not run a upload/receive-pack, we close the connection
 	// gracefully by sending a flush packet to the server. If the server
 	// operates correctly, it will exit with status 0.
 	if !s.packRun {
@@ -367,13 +367,13 @@ var (
 	eol = []byte("\n")
 )
 
-// fetchPack implements the git-fetch-pack protocol.
+// uploadPack implements the git-upload-pack protocol.
 //
 // 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 fetchPack(w io.WriteCloser, r io.Reader, req *packp.UploadPackRequest) error {
+func uploadPack(w io.WriteCloser, r io.Reader, req *packp.UploadPackRequest) error {
 	if err := req.UploadRequest.Encode(w); err != nil {
 		return fmt.Errorf("sending upload-req message: %s", err)
 	}
diff --git a/plumbing/transport/internal/common/server.go b/plumbing/transport/internal/common/server.go
new file mode 100644
index 0000000..dd6cfbe
--- /dev/null
+++ b/plumbing/transport/internal/common/server.go
@@ -0,0 +1,72 @@
+package common
+
+import (
+	"fmt"
+	"io"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp"
+	"gopkg.in/src-d/go-git.v4/plumbing/transport"
+	"gopkg.in/src-d/go-git.v4/utils/ioutil"
+)
+
+// ServerCommand is used for a single server command execution.
+type ServerCommand struct {
+	Stderr io.Writer
+	Stdout io.WriteCloser
+	Stdin  io.Reader
+}
+
+func ServeUploadPack(cmd ServerCommand, s transport.UploadPackSession) (err error) {
+	ioutil.CheckClose(cmd.Stdout, &err)
+
+	ar, err := s.AdvertisedReferences()
+	if err != nil {
+		return err
+	}
+
+	if err := ar.Encode(cmd.Stdout); err != nil {
+		return err
+	}
+
+	req := packp.NewUploadPackRequest()
+	if err := req.Decode(cmd.Stdin); err != nil {
+		return err
+	}
+
+	var resp *packp.UploadPackResponse
+	resp, err = s.UploadPack(req)
+	if err != nil {
+		return err
+	}
+
+	return resp.Encode(cmd.Stdout)
+}
+
+func ServeReceivePack(cmd ServerCommand, s transport.ReceivePackSession) error {
+	ar, err := s.AdvertisedReferences()
+	if err != nil {
+		return fmt.Errorf("internal error in advertised references: %s", err)
+	}
+
+	if err := ar.Encode(cmd.Stdout); err != nil {
+		return fmt.Errorf("error in advertised references encoding: %s", err)
+	}
+
+	req := packp.NewReferenceUpdateRequest()
+	if err := req.Decode(cmd.Stdin); err != nil {
+		return fmt.Errorf("error decoding: %s", err)
+	}
+
+	rs, err := s.ReceivePack(req)
+	if rs != nil {
+		if err := rs.Encode(cmd.Stdout); err != nil {
+			return fmt.Errorf("error in encoding report status %s", err)
+		}
+	}
+
+	if err != nil {
+		return fmt.Errorf("error in receive pack: %s", err)
+	}
+
+	return nil
+}