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.

1 files changed, 72 insertions, 0 deletions

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
+}