Merge pull request #5 from alcortesm/ssh

Ssh client for go-git

1 files changed, 205 insertions, 0 deletions

diff --git a/clients/ssh/git_upload_pack.go b/clients/ssh/git_upload_pack.go
new file mode 100644
index 0000000..09cb5ab
--- /dev/null
+++ b/clients/ssh/git_upload_pack.go
@@ -0,0 +1,205 @@
+// Package ssh implements a ssh client for go-git.
+//
+// The Connect() method is not allowed in ssh, use ConnectWithAuth() instead.
+package ssh
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/url"
+
+	"gopkg.in/src-d/go-git.v2/clients/common"
+	"gopkg.in/src-d/go-git.v2/formats/pktline"
+
+	"github.com/sourcegraph/go-vcsurl"
+	"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")
+)
+
+// GitUploadPackService holds the service information.
+// The zero value is safe to use.
+// TODO: remove NewGitUploadPackService().
+type GitUploadPackService struct {
+	connected bool
+	vcs       *vcsurl.RepoInfo
+	client    *ssh.Client
+	auth      AuthMethod
+}
+
+// NewGitUploadPackService initialises a GitUploadPackService.
+// TODO: remove this, as the struct is zero-value safe.
+func NewGitUploadPackService() *GitUploadPackService {
+	return &GitUploadPackService{}
+}
+
+// Connect cannot be used with SSH clients and always return
+// ErrAuthRequired. Use ConnectWithAuth instead.
+func (s *GitUploadPackService) Connect(ep common.Endpoint) (err error) {
+	return ErrAuthRequired
+}
+
+// ConnectWithAuth connects to ep using SSH. Authentication is handled
+// by auth.
+func (s *GitUploadPackService) ConnectWithAuth(ep common.Endpoint, auth common.AuthMethod) (err error) {
+	if s.connected {
+		return ErrAlreadyConnected
+	}
+
+	s.vcs, err = vcsurl.Parse(string(ep))
+	if err != nil {
+		return err
+	}
+
+	url, err := vcsToURL(s.vcs)
+	if err != nil {
+		return
+	}
+
+	var ok bool
+	s.auth, ok = auth.(AuthMethod)
+	if !ok {
+		return ErrInvalidAuthMethod
+	}
+
+	s.client, err = ssh.Dial("tcp", url.Host, s.auth.clientConfig())
+	if err != nil {
+		return err
+	}
+
+	s.connected = true
+	return
+}
+
+func vcsToURL(vcs *vcsurl.RepoInfo) (u *url.URL, err error) {
+	if vcs.VCS != vcsurl.Git {
+		return nil, ErrUnsupportedVCS
+	}
+	if vcs.RepoHost != vcsurl.GitHub {
+		return nil, ErrUnsupportedRepo
+	}
+	s := "ssh://git@" + string(vcs.RepoHost) + ":22/" + vcs.FullName
+	u, err = url.Parse(s)
+	return
+}
+
+// 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("git-upload-pack " + s.vcs.FullName + ".git")
+	if err != nil {
+		return nil, err
+	}
+
+	i = common.NewGitUploadPackInfo()
+	return i, i.Decode(pktline.NewDecoder(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 retrieves the GitUploadPack form the repository.
+// You must be connected to the repository before using this method
+// (using the ConnectWithAuth() method).
+// TODO: fetch should really reuse the info session instead of openning a new
+// one
+func (s *GitUploadPackService) Fetch(r *common.GitUploadPackRequest) (rc io.ReadCloser, 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()
+	}()
+
+	si, err := session.StdinPipe()
+	if err != nil {
+		return nil, err
+	}
+
+	so, err := session.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+
+	go func() {
+		fmt.Fprintln(si, r.String())
+		err = si.Close()
+	}()
+
+	err = session.Start("git-upload-pack " + s.vcs.FullName + ".git")
+	if err != nil {
+		return nil, err
+	}
+	// TODO: inestigate this *ExitError type (command fails or
+	// doesn't complete successfully), as it is happenning all
+	// the time, but everyting seems to work fine.
+	err = session.Wait()
+	if err != nil {
+		if _, ok := err.(*ssh.ExitError); !ok {
+			return nil, err
+		}
+	}
+
+	// read until the header of the second answer
+	soBuf := bufio.NewReader(so)
+	token := "0000"
+	for {
+		var line string
+		line, err = soBuf.ReadString('\n')
+		if err == io.EOF {
+			return nil, ErrUploadPackAnswerFormat
+		}
+		if line[0:len(token)] == token {
+			break
+		}
+	}
+
+	data, err := ioutil.ReadAll(soBuf)
+	if err != nil {
+		return nil, err
+	}
+	buf := bytes.NewBuffer(data)
+	return ioutil.NopCloser(buf), nil
+}