snow/wireguard-go
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Introduce rwcancel

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This commit is contained in:
Jason A. Donenfeld 2018-05-14 00:28:30 +02:00
parent e21ea58db3
commit 7e10ebe101
5 changed files with 170 additions and 75 deletions
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2
Makefile
View file

@ -1,6 +1,6 @@
all: wireguard-go
wireguard-go: $(wildcard *.go)
wireguard-go: $(wildcard *.go) $(wildcard */*.go)
go build -o $@
clean:

2
misc.go
View file

@ -47,7 +47,7 @@ func toInt32(n uint32) int32 {
return int32(-(n & mask) + (n & ^mask))
}
func min(a uint, b uint) uint {
func min(a, b uint) uint {
if a > b {
return b
}

132
rwcancel/rwcancel_unix.go Normal file
View file

@ -0,0 +1,132 @@
/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
package rwcancel
import (
"errors"
"golang.org/x/sys/unix"
"os"
"runtime"
"syscall"
)
type RWCancel struct {
fd int
closingReader *os.File
closingWriter *os.File
}
type fdSet struct {
fdset unix.FdSet
}
func (fdset *fdSet) set(i int) {
bits := 32 << (^uint(0) >> 63)
fdset.fdset.Bits[i/bits] |= 1 << uint(i%bits)
}
func (fdset *fdSet) check(i int) bool {
bits := 32 << (^uint(0) >> 63)
return (fdset.fdset.Bits[i/bits] & (1 << uint(i%bits))) != 0
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
func NewRWCancel(fd int) (*RWCancel, error) {
err := unix.SetNonblock(fd, true)
if err != nil {
return nil, err
}
rwcancel := RWCancel{fd: fd}
rwcancel.closingReader, rwcancel.closingWriter, err = os.Pipe()
if err != nil {
return nil, err
}
runtime.SetFinalizer(&rwcancel, func(rw *RWCancel) {
rw.Cancel()
})
return &rwcancel, nil
}
/* https://golang.org/src/crypto/rand/eagain.go */
func ErrorIsEAGAIN(err error) bool {
if pe, ok := err.(*os.PathError); ok {
if errno, ok := pe.Err.(syscall.Errno); ok && errno == syscall.EAGAIN {
return true
}
}
if errno, ok := err.(syscall.Errno); ok && errno == syscall.EAGAIN {
return true
}
return false
}
func (rw *RWCancel) ReadyRead() bool {
closeFd := int(rw.closingReader.Fd())
fdset := fdSet{}
fdset.set(rw.fd)
fdset.set(closeFd)
_, err := unix.Select(max(rw.fd, closeFd)+1, &fdset.fdset, nil, nil, nil)
if err != nil {
return false
}
if fdset.check(closeFd) {
return false
}
return fdset.check(rw.fd)
}
func (rw *RWCancel) ReadyWrite() bool {
closeFd := int(rw.closingReader.Fd())
fdset := fdSet{}
fdset.set(rw.fd)
fdset.set(closeFd)
_, err := unix.Select(max(rw.fd, closeFd)+1, nil, &fdset.fdset, nil, nil)
if err != nil {
return false
}
if fdset.check(closeFd) {
return false
}
return fdset.check(rw.fd)
}
func (rw *RWCancel) Read(p []byte) (n int, err error) {
for {
n, err := unix.Read(rw.fd, p)
if err == nil || !ErrorIsEAGAIN(err) {
return n, err
}
if !rw.ReadyRead() {
return 0, errors.New("fd closed")
}
}
}
func (rw *RWCancel) Write(p []byte) (n int, err error) {
for {
n, err := unix.Write(rw.fd, p)
if err == nil || !ErrorIsEAGAIN(err) {
return n, err
}
if !rw.ReadyWrite() {
return 0, errors.New("fd closed")
}
}
}
func (rw *RWCancel) Cancel() (err error) {
_, err = rw.closingWriter.Write([]byte{0})
return
}

79
tun_linux.go
View file

@ -11,6 +11,7 @@ package main
*/
import (
"./rwcancel"
"bytes"
"encoding/binary"
"errors"
@ -20,7 +21,6 @@ import (
"net"
"os"
"strconv"
"syscall"
"time"
"unsafe"
)
@ -31,14 +31,13 @@ const (
)
type NativeTun struct {
fd *os.File
index int32 // if index
name string // name of interface
errors chan error // async error handling
events chan TUNEvent // device related events
nopi bool // the device was pased IFF_NO_PI
closingReader *os.File
closingWriter *os.File
fd *os.File
index int32 // if index
name string // name of interface
errors chan error // async error handling
events chan TUNEvent // device related events
nopi bool // the device was pased IFF_NO_PI
rwcancel *rwcancel.RWCancel
}
func (tun *NativeTun) File() *os.File {
@ -305,43 +304,6 @@ func (tun *NativeTun) Write(buff []byte, offset int) (int, error) {
return tun.fd.Write(buff)
}
type FdSet struct {
fdset unix.FdSet
}
func (fdset *FdSet) set(i int) {
bits := 32 << (^uint(0) >> 63)
fdset.fdset.Bits[i/bits] |= 1 << uint(i%bits)
}
func (fdset *FdSet) check(i int) bool {
bits := 32 << (^uint(0) >> 63)
return (fdset.fdset.Bits[i/bits] & (1 << uint(i%bits))) != 0
}
func max(a, b int) int {
if a > b {
return a
}
return b
}
func (tun *NativeTun) readyRead() bool {
readFd := int(tun.fd.Fd())
closeFd := int(tun.closingReader.Fd())
fdset := FdSet{}
fdset.set(readFd)
fdset.set(closeFd)
_, err := unix.Select(max(readFd, closeFd)+1, &fdset.fdset, nil, nil, nil)
if err != nil {
return false
}
if fdset.check(closeFd) {
return false
}
return fdset.check(readFd)
}
func (tun *NativeTun) doRead(buff []byte, offset int) (int, error) {
select {
case err := <-tun.errors:
@ -360,24 +322,14 @@ func (tun *NativeTun) doRead(buff []byte, offset int) (int, error) {
}
}
/* https://golang.org/src/crypto/rand/eagain.go */
func unixIsEAGAIN(err error) bool {
if pe, ok := err.(*os.PathError); ok {
if errno, ok := pe.Err.(syscall.Errno); ok && errno == syscall.EAGAIN {
return true
}
}
return false
}
func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
for {
n, err := tun.doRead(buff, offset)
if err == nil || !unixIsEAGAIN(err) {
if err == nil || !rwcancel.ErrorIsEAGAIN(err) {
return n, err
}
if !tun.readyRead() {
return 0, errors.New("Tun device closed")
if !tun.rwcancel.ReadyRead() {
return 0, errors.New("tun device closed")
}
}
}
@ -391,7 +343,7 @@ func (tun *NativeTun) Close() error {
if err != nil {
return err
}
tun.closingWriter.Write([]byte{0})
tun.rwcancel.Cancel()
close(tun.events)
return nil
}
@ -450,7 +402,7 @@ func CreateTUNFromFile(fd *os.File) (TUNDevice, error) {
}
var err error
err = unix.SetNonblock(int(fd.Fd()), true)
device.rwcancel, err = rwcancel.NewRWCancel(int(fd.Fd()))
if err != nil {
return nil, err
}
@ -460,11 +412,6 @@ func CreateTUNFromFile(fd *os.File) (TUNDevice, error) {
return nil, err
}
device.closingReader, device.closingWriter, err = os.Pipe()
if err != nil {
return nil, err
}
// start event listener
device.index, err = getIFIndex(device.name)

30
uapi_linux.go
View file

@ -6,6 +6,7 @@
package main
import (
"./rwcancel"
"errors"
"fmt"
"golang.org/x/sys/unix"
@ -24,10 +25,11 @@ const (
)
type UAPIListener struct {
listener net.Listener // unix socket listener
connNew chan net.Conn
connErr chan error
inotifyFd int
listener net.Listener // unix socket listener
connNew chan net.Conn
connErr chan error
inotifyFd int
inotifyRWCancel *rwcancel.RWCancel
}
func (l *UAPIListener) Accept() (net.Conn, error) {
@ -45,10 +47,14 @@ func (l *UAPIListener) Accept() (net.Conn, error) {
func (l *UAPIListener) Close() error {
err1 := unix.Close(l.inotifyFd)
err2 := l.listener.Close()
err3 := l.inotifyRWCancel.Cancel()
if err1 != nil {
return err1
}
return err2
if err2 != nil {
return err2
}
return err3
}
func (l *UAPIListener) Addr() net.Addr {
@ -94,15 +100,25 @@ func UAPIListen(name string, file *os.File) (net.Listener, error) {
return nil, err
}
uapi.inotifyRWCancel, err = rwcancel.NewRWCancel(uapi.inotifyFd)
if err != nil {
unix.Close(uapi.inotifyFd)
return nil, err
}
go func(l *UAPIListener) {
var buff [4096]byte
var buff [0]byte
for {
// start with lstat to avoid race condition
if _, err := os.Lstat(socketPath); os.IsNotExist(err) {
l.connErr <- err
return
}
unix.Read(uapi.inotifyFd, buff[:])
_, err := uapi.inotifyRWCancel.Read(buff[:])
if err != nil {
l.connErr <- err
return
}
}
}(uapi)