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ssh.go
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ssh.go
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package main
import (
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"io"
"io/ioutil"
"log"
"net"
"os/exec"
"path/filepath"
"strings"
"golang.org/x/crypto/ssh"
)
var allowedCommands = map[string]bool{
"git-upload-pack": true,
"git-upload-archive": true,
"git-receive-pack": true,
}
type SSHServer struct {
HostKey *rsa.PrivateKey
PublicKey *rsa.PublicKey
SrvListener net.Listener
Stop chan bool
}
func NewSSHServer() (*SSHServer, error) {
ssh := &SSHServer{
Stop: make(chan bool),
}
err := ssh.LoadPrivateKey(Settings.SSHHostKey)
if err != nil {
log.Printf("Failed to start SSH server: %v", err)
return nil, err
}
return ssh, nil
}
func (s *SSHServer) LoadPrivateKey(path string) error {
var err error
if FileExist(path) {
pkey, err := ioutil.ReadFile(path)
if err != nil {
return err
}
skey, _ := pem.Decode(pkey)
s.HostKey, err = x509.ParsePKCS1PrivateKey(skey.Bytes)
return err
} else {
log.Printf("HostKey not found, generate host key")
s.HostKey, err = GenerateKey()
if err != nil {
return err
}
// save host key
pkey := KeyEncode(s.HostKey, true)
err = ioutil.WriteFile(path, pkey, 0666)
if err != nil {
return err
}
}
return nil
}
func (s *SSHServer) LoadPublicKey(path string) error {
pkey, err := ioutil.ReadFile(path)
if err != nil {
return err
}
skey, _ := pem.Decode(pkey)
s.PublicKey, err = x509.ParsePKCS1PublicKey(skey.Bytes)
return err
}
func handleChannels(chans <-chan ssh.NewChannel) {
for newChan := range chans {
if newChan.ChannelType() != "session" {
newChan.Reject(ssh.UnknownChannelType, "unknown channel type")
continue
}
ch, reqs, err := newChan.Accept()
if err != nil {
log.Printf("Error accepting channel: %v", err)
continue
}
go func(in <-chan *ssh.Request) {
defer ch.Close()
for req := range in {
log.Printf("SSH: Req.Type: '%#v'", req.Type)
switch req.Type {
case "env":
log.Printf("SSH: Invalid env arguments: '%#v'", string(req.Payload))
case "exec":
if len(req.Payload) < 5 {
log.Printf("SSH: Payload Empty: %v", req.Payload)
return
}
payload := strings.SplitN(string(req.Payload[4:]), " ", 2)
// cmdName := payload
log.Printf("SSH: Payload: %v", payload)
path := filepath.Join(Settings.GitRoot, strings.Trim(payload[1], "':"))
log.Printf("SSH: Payload path: %v", path)
cmd := exec.Command(payload[0], path)
stdout, err := cmd.StdoutPipe()
if err != nil {
log.Printf("SSH: StdoutPipe: %v", err)
return
}
stderr, err := cmd.StderrPipe()
if err != nil {
log.Printf("SSH: StderrPipe: %v", err)
return
}
input, err := cmd.StdinPipe()
if err != nil {
log.Printf("SSH: StdinPipe: %v", err)
return
}
// FIXME: check timeout
if err = cmd.Start(); err != nil {
log.Printf("SSH: Start: %v", err)
return
}
req.Reply(true, nil)
go io.Copy(input, ch)
io.Copy(ch, stdout)
io.Copy(ch.Stderr(), stderr)
if err = cmd.Wait(); err != nil {
log.Printf("SSH: Wait: %v", err)
return
}
ch.SendRequest("exit-status", false, []byte{0, 0, 0, 0})
return
default:
return
}
}
}(reqs)
}
}
func (s *SSHServer) ListenAndServe(addr string) error {
config := &ssh.ServerConfig{
PublicKeyCallback: func(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
// @todo auth force-command
// if conn.User() == "foo" {
// pub := base64.StdEncoding.EncodeToString(key.Marshal())
// result := strings.Compare(pub, pubkey)
// if result == 0 {
// return nil, nil
// }
// }
// return &ssh.Permissions{Extensions: map[string]string{"key-id": ""}}, nil
return nil, nil
},
PasswordCallback: func(conn ssh.ConnMetadata, password []byte) (*ssh.Permissions, error) {
return nil, nil
},
}
hostKey, err := ssh.NewSignerFromKey(s.HostKey)
if err != nil {
return err
}
config.AddHostKey(hostKey)
s.SrvListener, err = net.Listen("tcp", addr)
if err != nil {
return err
}
for {
conn, err := s.SrvListener.Accept()
if err != nil {
log.Printf("SSH: Error accepting incoming connection: %v", err)
continue
}
go func() {
log.Printf("SSH: Handshaking for %s", conn.RemoteAddr())
sConn, chans, reqs, err := ssh.NewServerConn(conn, config)
if err != nil {
if err == io.EOF {
log.Printf("SSH: Handshaking was terminated: %v", err)
} else {
log.Printf("SSH: Error on handshaking: %v", err)
}
return
}
log.Printf("SSH: Connection from %s (%s)", sConn.RemoteAddr(), sConn.ClientVersion())
// The incoming Request channel must be serviced.
go ssh.DiscardRequests(reqs)
go handleChannels(chans)
}()
}
}
func (s *SSHServer) Shutdown() error {
log.Printf("Shutdown SSH Server...")
// @TODO
s.Stop <- true
return nil
}