From 7e10ebe1010898c48e3f1cfc12ad42d0bb5c0fa1 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 14 May 2018 00:28:30 +0200
Subject: [PATCH] Introduce rwcancel
---
Makefile | 2 +-
misc.go | 2 +-
rwcancel/rwcancel_unix.go | 132 ++++++++++++++++++++++++++++++++++++++
tun_linux.go | 79 ++++-------------------
uapi_linux.go | 30 +++++++--
5 files changed, 170 insertions(+), 75 deletions(-)
create mode 100644 rwcancel/rwcancel_unix.go
diff --git a/Makefile b/Makefile
index 77eaac9..1513ef5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
all: wireguard-go
-wireguard-go: $(wildcard *.go)
+wireguard-go: $(wildcard *.go) $(wildcard */*.go)
go build -o $@
clean:
diff --git a/misc.go b/misc.go
index f94a617..85a2e80 100644
--- a/misc.go
+++ b/misc.go
@@ -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
}
diff --git a/rwcancel/rwcancel_unix.go b/rwcancel/rwcancel_unix.go
new file mode 100644
index 0000000..cd3661f
--- /dev/null
+++ b/rwcancel/rwcancel_unix.go
@@ -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
+}
diff --git a/tun_linux.go b/tun_linux.go
index 9f60d2b..3510f94 100644
--- a/tun_linux.go
+++ b/tun_linux.go
@@ -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)
diff --git a/uapi_linux.go b/uapi_linux.go
index c40472e..67024e9 100644
--- a/uapi_linux.go
+++ b/uapi_linux.go
@@ -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)