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// 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.v3/clients/common"
"gopkg.in/src-d/go-git.v3/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
}
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