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net/tshttpproxy: fix incorrect type in Windows implementation, switch to mkwinsyscall, fix memory leak

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The definition of winHTTPProxyInfo was using the wrong type (uint16 vs uint32)
for its first field. I fixed that type.

Furthermore, any UTF16 strings returned in that structure must be explicitly
freed. I added code to do this.

Finally, since this is the second time I've seen type safety errors in this code,
I switched the native API calls over to use wrappers generated by mkwinsyscall.
I know that would not have helped prevent the previous two problems, but every
bit helps IMHO.

Updates https://github.com/tailscale/tailscale/issues/4811

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
pull/5200/head
Aaron Klotz 2 years ago
parent 446d03e108
commit 4dbdb19c26
3 changed files with 133 additions and 44 deletions
Show Stats Download Patch File Download Diff File

12
net/tshttpproxy/mksyscall.go
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@ -0,0 +1,12 @@
// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tshttpproxy
//go:generate go run golang.org/x/sys/windows/mkwinsyscall -output zsyscall_windows.go mksyscall.go
//sys globalFree(hglobal winHGlobal) (err error) [failretval==0] = kernel32.GlobalFree
//sys winHTTPCloseHandle(whi winHTTPInternet) (err error) [failretval==0] = winhttp.WinHttpCloseHandle
//sys winHTTPGetProxyForURL(whi winHTTPInternet, url *uint16, options *winHTTPAutoProxyOptions, proxyInfo *winHTTPProxyInfo) (err error) [failretval==0] = winhttp.WinHttpGetProxyForUrl
//sys winHTTPOpen(agent *uint16, accessType uint32, proxy *uint16, proxyBypass *uint16, flags uint32) (whi winHTTPInternet, err error) [failretval==0] = winhttp.WinHttpOpen

84
net/tshttpproxy/tshttpproxy_windows.go
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@ -26,13 +26,6 @@ import (
"tailscale.com/util/cmpver"
)
var (
winHTTP = windows.NewLazySystemDLL("winhttp.dll")
httpOpenProc = winHTTP.NewProc("WinHttpOpen")
closeHandleProc = winHTTP.NewProc("WinHttpCloseHandle")
getProxyForUrlProc = winHTTP.NewProc("WinHttpGetProxyForUrl")
)
func init() {
sysProxyFromEnv = proxyFromWinHTTPOrCache
sysAuthHeader = sysAuthHeaderWindows
@ -116,7 +109,7 @@ func proxyFromWinHTTP(ctx context.Context, urlStr string) (proxy *url.URL, err e
runtime.LockOSThread()
defer runtime.UnlockOSThread()
whi, err := winHTTPOpen()
whi, err := httpOpen()
if err != nil {
proxyErrorf("winhttp: Open: %v", err)
return nil, err
@ -178,38 +171,25 @@ func getAccessFlag() uint32 {
return flag
}
func winHTTPOpen() (winHTTPInternet, error) {
if err := httpOpenProc.Find(); err != nil {
return 0, err
}
r, _, err := httpOpenProc.Call(
uintptr(unsafe.Pointer(userAgent)),
uintptr(getAccessFlag()),
0, /* WINHTTP_NO_PROXY_NAME */
0, /* WINHTTP_NO_PROXY_BYPASS */
0)
if r == 0 {
return 0, err
}
return winHTTPInternet(r), nil
func httpOpen() (winHTTPInternet, error) {
return winHTTPOpen(
userAgent,
getAccessFlag(),
nil, /* WINHTTP_NO_PROXY_NAME */
nil, /* WINHTTP_NO_PROXY_BYPASS */
0,
)
}
type winHTTPInternet windows.Handle
func (hi winHTTPInternet) Close() error {
if err := closeHandleProc.Find(); err != nil {
return err
}
r, _, err := closeHandleProc.Call(uintptr(hi))
if r == 1 {
return nil
}
return err
return winHTTPCloseHandle(hi)
}
// WINHTTP_AUTOPROXY_OPTIONS
// https://docs.microsoft.com/en-us/windows/win32/api/winhttp/ns-winhttp-winhttp_autoproxy_options
type autoProxyOptions struct {
type winHTTPAutoProxyOptions struct {
DwFlags uint32
DwAutoDetectFlags uint32
AutoConfigUrl *uint16
@ -221,30 +201,46 @@ type autoProxyOptions struct {
// WINHTTP_PROXY_INFO
// https://docs.microsoft.com/en-us/windows/win32/api/winhttp/ns-winhttp-winhttp_proxy_info
type winHTTPProxyInfo struct {
AccessType uint16
AccessType uint32
Proxy *uint16
ProxyBypass *uint16
}
var proxyForURLOpts = &autoProxyOptions{
type winHGlobal windows.Handle
func globalFreeUTF16Ptr(p *uint16) error {
return globalFree((winHGlobal)(unsafe.Pointer(p)))
}
func (pi *winHTTPProxyInfo) free() {
if pi.Proxy != nil {
globalFreeUTF16Ptr(pi.Proxy)
pi.Proxy = nil
}
if pi.ProxyBypass != nil {
globalFreeUTF16Ptr(pi.ProxyBypass)
pi.ProxyBypass = nil
}
}
var proxyForURLOpts = &winHTTPAutoProxyOptions{
DwFlags: winHTTP_AUTOPROXY_ALLOW_AUTOCONFIG | winHTTP_AUTOPROXY_AUTO_DETECT,
DwAutoDetectFlags: winHTTP_AUTO_DETECT_TYPE_DHCP, // | winHTTP_AUTO_DETECT_TYPE_DNS_A,
}
func (hi winHTTPInternet) GetProxyForURL(urlStr string) (string, error) {
if err := getProxyForUrlProc.Find(); err != nil {
return "", err
}
var out winHTTPProxyInfo
r, _, err := getProxyForUrlProc.Call(
uintptr(hi),
uintptr(unsafe.Pointer(windows.StringToUTF16Ptr(urlStr))),
uintptr(unsafe.Pointer(proxyForURLOpts)),
uintptr(unsafe.Pointer(&out)))
if r == 1 {
return windows.UTF16PtrToString(out.Proxy), nil
err := winHTTPGetProxyForURL(
hi,
windows.StringToUTF16Ptr(urlStr),
proxyForURLOpts,
&out,
)
if err != nil {
return "", err
}
return "", err
defer out.free()
return windows.UTF16PtrToString(out.Proxy), nil
}
func sysAuthHeaderWindows(u *url.URL) (string, error) {

81
net/tshttpproxy/zsyscall_windows.go
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@ -0,0 +1,81 @@
// Code generated by 'go generate'; DO NOT EDIT.
package tshttpproxy
import (
"syscall"
"unsafe"
"golang.org/x/sys/windows"
)
var _ unsafe.Pointer
// Do the interface allocations only once for common
// Errno values.
const (
errnoERROR_IO_PENDING = 997
)
var (
errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
errERROR_EINVAL error = syscall.EINVAL
)
// errnoErr returns common boxed Errno values, to prevent
// allocations at runtime.
func errnoErr(e syscall.Errno) error {
switch e {
case 0:
return errERROR_EINVAL
case errnoERROR_IO_PENDING:
return errERROR_IO_PENDING
}
// TODO: add more here, after collecting data on the common
// error values see on Windows. (perhaps when running
// all.bat?)
return e
}
var (
modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
modwinhttp = windows.NewLazySystemDLL("winhttp.dll")
procGlobalFree = modkernel32.NewProc("GlobalFree")
procWinHttpCloseHandle = modwinhttp.NewProc("WinHttpCloseHandle")
procWinHttpGetProxyForUrl = modwinhttp.NewProc("WinHttpGetProxyForUrl")
procWinHttpOpen = modwinhttp.NewProc("WinHttpOpen")
)
func globalFree(hglobal winHGlobal) (err error) {
r1, _, e1 := syscall.Syscall(procGlobalFree.Addr(), 1, uintptr(hglobal), 0, 0)
if r1 == 0 {
err = errnoErr(e1)
}
return
}
func winHTTPCloseHandle(whi winHTTPInternet) (err error) {
r1, _, e1 := syscall.Syscall(procWinHttpCloseHandle.Addr(), 1, uintptr(whi), 0, 0)
if r1 == 0 {
err = errnoErr(e1)
}
return
}
func winHTTPGetProxyForURL(whi winHTTPInternet, url *uint16, options *winHTTPAutoProxyOptions, proxyInfo *winHTTPProxyInfo) (err error) {
r1, _, e1 := syscall.Syscall6(procWinHttpGetProxyForUrl.Addr(), 4, uintptr(whi), uintptr(unsafe.Pointer(url)), uintptr(unsafe.Pointer(options)), uintptr(unsafe.Pointer(proxyInfo)), 0, 0)
if r1 == 0 {
err = errnoErr(e1)
}
return
}
func winHTTPOpen(agent *uint16, accessType uint32, proxy *uint16, proxyBypass *uint16, flags uint32) (whi winHTTPInternet, err error) {
r0, _, e1 := syscall.Syscall6(procWinHttpOpen.Addr(), 5, uintptr(unsafe.Pointer(agent)), uintptr(accessType), uintptr(unsafe.Pointer(proxy)), uintptr(unsafe.Pointer(proxyBypass)), uintptr(flags), 0)
whi = winHTTPInternet(r0)
if whi == 0 {
err = errnoErr(e1)
}
return
}
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