forked from sanbornm/go-selfupdate
/
selfupdate.go
290 lines (265 loc) · 6.43 KB
/
selfupdate.go
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// Update protocol:
//
// GET hk.heroku.com/hk/linux-amd64.json
//
// 200 ok
// {
// "Version": "2",
// "Sha256": "..." // base64
// }
//
// then
//
// GET hkpatch.s3.amazonaws.com/hk/1/2/linux-amd64
//
// 200 ok
// [bsdiff data]
//
// or
//
// GET hkdist.s3.amazonaws.com/hk/2/linux-amd64.gz
//
// 200 ok
// [gzipped executable data]
//
//
package selfupdate
import (
"bytes"
"compress/gzip"
"crypto/sha256"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"log"
"math/rand"
"net/http"
"os"
"path/filepath"
"runtime"
"time"
"github.com/kardianos/osext"
"github.com/kr/binarydist"
"gopkg.in/inconshreveable/go-update.v0"
)
const (
upcktimePath = "cktime"
plat = runtime.GOOS + "-" + runtime.GOARCH
)
const devValidTime = 7 * 24 * time.Hour
var ErrHashMismatch = errors.New("new file hash mismatch after patch")
var up = update.New()
// Updater is the configuration and runtime data for doing an update.
//
// Note that ApiURL, BinURL and DiffURL should have the same value if all files are available at the same location.
//
// Example:
//
// updater := &selfupdate.Updater{
// CurrentVersion: version,
// ApiURL: "http://updates.yourdomain.com/",
// BinURL: "http://updates.yourdownmain.com/",
// DiffURL: "http://updates.yourdomain.com/",
// Dir: "update/",
// CmdName: "myapp", // app name
// }
// if updater != nil {
// go updater.BackgroundRun()
// }
type Updater struct {
CurrentVersion string // Currently running version.
ApiURL string // Base URL for API requests (json files).
CmdName string // Command name is appended to the ApiURL like http://apiurl/CmdName/. This represents one binary.
BinURL string // Base URL for full binary downloads.
DiffURL string // Base URL for diff downloads.
Dir string // Directory to store selfupdate state.
Info struct {
Version string
Sha256 []byte
}
}
func (u *Updater) getExecRelativeDir(dir string) string {
if dir[0] == '/' {
return dir
}
filename, _ := osext.Executable()
path := filepath.Join(filepath.Dir(filename), dir)
return path
}
// BackgroundRun starts the update check and apply cycle.
func (u *Updater) BackgroundRun() error {
os.MkdirAll(u.getExecRelativeDir(u.Dir), 0777)
if err := up.CanUpdate(); err != nil {
// fail
return err
}
//self, err := osext.Executable()
//if err != nil {
// fail update, couldn't figure out path to self
//return
//}
// TODO(bgentry): logger isn't on Windows. Replace w/ proper error reports.
if err := u.update(); err != nil {
return err
}
return nil
}
func (u *Updater) WantUpdate() bool {
os.MkdirAll(u.getExecRelativeDir(u.Dir), 0777)
path := u.getExecRelativeDir(u.Dir + upcktimePath)
if readTime(path).After(time.Now()) {
return false
}
wait := 24*time.Hour + randDuration(24*time.Hour)
writeTime(path, time.Now().Add(wait))
return true
}
func (u *Updater) update() error {
path, err := osext.Executable()
if err != nil {
return err
}
old, err := os.Open(path)
if err != nil {
return err
}
defer old.Close()
err = u.fetchInfo()
if err != nil {
return err
}
if u.Info.Version == u.CurrentVersion {
log.Println("update: no new version available")
return nil
}
log.Println("update: fetching binary patch")
bin, err := u.fetchAndVerifyPatch(old)
if err != nil {
if err == ErrHashMismatch {
log.Println("update: hash mismatch from patched binary")
} else {
if u.DiffURL != "" {
log.Println("update: error while patching binary,", err)
}
}
log.Println("update: fetching full binary")
bin, err = u.fetchAndVerifyFullBin()
if err != nil {
if err == ErrHashMismatch {
log.Println("update: hash mismatch from full binary")
} else {
log.Println("update: error while fetching full binary,", err)
}
return err
}
}
// close the old binary before installing because on windows
// it can't be renamed if a handle to the file is still open
old.Close()
err, errRecover := up.FromStream(bytes.NewBuffer(bin))
if errRecover != nil {
return fmt.Errorf("update and recovery errors: %q %q", err, errRecover)
}
if err != nil {
return err
}
log.Println("update: software updated correctly")
return nil
}
func (u *Updater) fetchInfo() error {
r, err := fetch(u.ApiURL + u.CmdName + "/" + plat + ".json")
if err != nil {
return err
}
defer r.Close()
err = json.NewDecoder(r).Decode(&u.Info)
if err != nil {
return err
}
if len(u.Info.Sha256) != sha256.Size {
return errors.New("bad cmd hash in info")
}
return nil
}
func (u *Updater) fetchAndVerifyPatch(old io.Reader) ([]byte, error) {
bin, err := u.fetchAndApplyPatch(old)
if err != nil {
return nil, err
}
if !verifySha(bin, u.Info.Sha256) {
return nil, ErrHashMismatch
}
return bin, nil
}
func (u *Updater) fetchAndApplyPatch(old io.Reader) ([]byte, error) {
r, err := fetch(u.DiffURL + u.CmdName + "/" + u.CurrentVersion + "/" + u.Info.Version + "/" + plat)
if err != nil {
return nil, err
}
defer r.Close()
var buf bytes.Buffer
err = binarydist.Patch(old, &buf, r)
return buf.Bytes(), err
}
func (u *Updater) fetchAndVerifyFullBin() ([]byte, error) {
bin, err := u.fetchBin()
if err != nil {
return nil, err
}
verified := verifySha(bin, u.Info.Sha256)
if !verified {
return nil, ErrHashMismatch
}
return bin, nil
}
func (u *Updater) fetchBin() ([]byte, error) {
r, err := fetch(u.BinURL + u.CmdName + "/" + u.Info.Version + "/" + plat + ".gz")
if err != nil {
return nil, err
}
defer r.Close()
buf := new(bytes.Buffer)
gz, err := gzip.NewReader(r)
if err != nil {
return nil, err
}
if _, err = io.Copy(buf, gz); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// returns a random duration in [0,n).
func randDuration(n time.Duration) time.Duration {
return time.Duration(rand.Int63n(int64(n)))
}
func fetch(url string) (io.ReadCloser, error) {
resp, err := http.Get(url)
if err != nil {
return nil, err
}
if resp.StatusCode != 200 {
return nil, fmt.Errorf("bad http status from %s: %v", url, resp.Status)
}
return resp.Body, nil
}
func readTime(path string) time.Time {
fi, err := os.Stat(path)
if err != nil {
return time.Time{}
}
return fi.ModTime()
}
func verifySha(bin []byte, sha []byte) bool {
h := sha256.New()
h.Write(bin)
return bytes.Equal(h.Sum(nil), sha)
}
func writeTime(path string, t time.Time) {
err := os.Chtimes(path, t, t)
if os.IsNotExist(err) {
ioutil.WriteFile(path, nil, 0666)
os.Chtimes(path, t, t)
}
}