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|
// Package ssh implements a ssh client for go-git.
package ssh
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"strings"
"gopkg.in/src-d/go-git.v4/clients/common"
"gopkg.in/src-d/go-git.v4/formats/packp/pktline"
"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.
type GitUploadPackService struct {
connected bool
endpoint common.Endpoint
client *ssh.Client
auth AuthMethod
}
// NewGitUploadPackService initialises a GitUploadPackService,
func NewGitUploadPackService(endpoint common.Endpoint) common.GitUploadPackService {
return &GitUploadPackService{endpoint: endpoint}
}
// Connect connects to the SSH server, unless a AuthMethod was set with SetAuth
// method, by default uses an auth method based on PublicKeysCallback, it
// connects to a SSH agent, using the address stored in the SSH_AUTH_SOCK
// environment var
func (s *GitUploadPackService) Connect() error {
if s.connected {
return ErrAlreadyConnected
}
if err := s.setAuthFromEndpoint(); err != nil {
return err
}
var err error
s.client, err = ssh.Dial("tcp", s.getHostWithPort(), s.auth.clientConfig())
if err != nil {
return err
}
s.connected = true
return nil
}
func (s *GitUploadPackService) getHostWithPort() string {
host := s.endpoint.Host
if strings.Index(s.endpoint.Host, ":") == -1 {
host += ":22"
}
return host
}
func (s *GitUploadPackService) setAuthFromEndpoint() error {
var u string
if info := s.endpoint.User; info != nil {
u = info.Username()
}
var err error
s.auth, err = NewSSHAgentAuth(u)
if err != nil {
return err
}
return nil
}
// SetAuth sets the AuthMethod
func (s *GitUploadPackService) SetAuth(auth common.AuthMethod) error {
var ok bool
s.auth, ok = auth.(AuthMethod)
if !ok {
return ErrInvalidAuthMethod
}
return nil
}
// 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(s.getCommand())
if err != nil {
return nil, err
}
i = common.NewGitUploadPackInfo()
return i, i.Decode(pktline.NewScanner(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
}
if err := session.Start(s.getCommand()); err != nil {
return nil, err
}
go func() {
fmt.Fprintln(si, r.String())
err = si.Close()
}()
// TODO: investigate this *ExitError type (command fails or
// doesn't complete successfully), as it is happenning all
// the time, but everything seems to work fine.
if err := session.Wait(); 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
}
func (s *GitUploadPackService) getCommand() string {
directory := s.endpoint.Path
directory = directory[1:len(directory)]
return fmt.Sprintf("git-upload-pack %s", directory)
}
|
