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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package updater
import (
"crypto/hmac"
"errors"
"fmt"
"golang.org/x/crypto/blake2b"
"golang.zx2c4.com/wireguard/windows/version"
"hash"
"io"
"net/http"
"os"
"sync/atomic"
)
type DownloadProgress struct {
Activity string
BytesDownloaded uint64
BytesTotal uint64
Error error
Complete bool
}
type progressHashWatcher struct {
dp *DownloadProgress
c chan DownloadProgress
hashState hash.Hash
}
func (pm *progressHashWatcher) Write(p []byte) (int, error) {
bytes := len(p)
pm.dp.BytesDownloaded += uint64(bytes)
pm.c <- *pm.dp
pm.hashState.Write(p)
return bytes, nil
}
type UpdateFound struct {
name string
hash [blake2b.Size256]byte
}
func CheckForUpdate() (*UpdateFound, error) {
request, err := http.NewRequest(http.MethodGet, latestVersionURL, nil)
if err != nil {
return nil, err
}
request.Header.Add("User-Agent", version.UserAgent())
response, err := http.DefaultClient.Do(request)
if err != nil {
return nil, err
}
defer response.Body.Close()
var fileList [1024 * 512] /* 512 KiB */ byte
bytesRead, err := response.Body.Read(fileList[:])
if err != nil && (err != io.EOF || bytesRead == 0) {
return nil, err
}
files, err := readFileList(fileList[:bytesRead])
if err != nil {
return nil, err
}
return findCandidate(files)
}
var updateInProgress = uint32(0)
func DownloadVerifyAndExecute(userToken uintptr) (progress chan DownloadProgress) {
progress = make(chan DownloadProgress, 128)
progress <- DownloadProgress{Activity: "Initializing"}
if !atomic.CompareAndSwapUint32(&updateInProgress, 0, 1) {
progress <- DownloadProgress{Error: errors.New("An update is already in progress")}
return
}
go func() {
defer atomic.StoreUint32(&updateInProgress, 0)
progress <- DownloadProgress{Activity: "Rechecking for update"}
update, err := CheckForUpdate()
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
if update == nil {
progress <- DownloadProgress{Error: errors.New("No update was found when re-checking for updates")}
return
}
progress <- DownloadProgress{Activity: "Creating temporary file"}
file, err := msiTempFile()
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
defer func() {
if file != nil {
name := file.Name()
file.Seek(0, io.SeekStart)
file.Truncate(0)
file.Close()
os.Remove(name) //TODO: Do we have any sort of TOCTOU here?
}
}()
dp := DownloadProgress{Activity: "Downloading update"}
progress <- dp
request, err := http.NewRequest(http.MethodGet, fmt.Sprintf(msiURL, update.name), nil)
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
request.Header.Add("User-Agent", version.UserAgent())
request.Header.Set("Accept-Encoding", "identity")
response, err := http.DefaultClient.Do(request)
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
defer response.Body.Close()
if response.ContentLength >= 0 {
dp.BytesTotal = uint64(response.ContentLength)
progress <- dp
}
hasher, err := blake2b.New256(nil)
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
pm := &progressHashWatcher{&dp, progress, hasher}
_, err = io.Copy(file, io.TeeReader(io.LimitReader(response.Body, 1024*1024*100 /* 100 MiB */), pm))
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
if !hmac.Equal(hasher.Sum(nil), update.hash[:]) {
progress <- DownloadProgress{Error: errors.New("The downloaded update has the wrong hash")}
return
}
//TODO: it would be nice to rename in place from "file.msi.unverified" to "file.msi", but Windows TOCTOU stuff
// is hard, so we'll come back to this later.
name := file.Name()
file.Close()
file = nil
progress <- DownloadProgress{Activity: "Verifying authenticode signature"}
if !version.VerifyAuthenticode(name) {
os.Remove(name) //TODO: Do we have any sort of TOCTOU here?
progress <- DownloadProgress{Error: errors.New("The downloaded update does not have an authentic authenticode signature")}
return
}
progress <- DownloadProgress{Activity: "Installing update"}
err = runMsi(name, userToken)
os.Remove(name) //TODO: Do we have any sort of TOCTOU here?
if err != nil {
progress <- DownloadProgress{Error: err}
return
}
progress <- DownloadProgress{Complete: true}
}()
return progress
}
|
