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tun: windows: mitigate infinite loop in Flush()

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It's possible that for whatever reason, we keep returning EOF, resulting
in repeated close/open/write operations, except with empty packets.
This commit is contained in:
Jason A. Donenfeld 2019-05-31 15:40:08 +02:00
parent d9f995209c
commit da61947ec3
1 changed files with 35 additions and 29 deletions
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38
tun/tun_windows.go
View file

@ -8,6 +8,7 @@ package tun
import (
"errors"
"fmt"
"io"
"os"
"sync"
"time"
@ -230,6 +231,7 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
default:
}
retries := 1000
for {
if tun.rdBuff.offset+packetExchangeAlignment <= tun.rdBuff.avail {
// Get packet from the exchange buffer.
@ -255,9 +257,6 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
return 0, err
}
// Fill queue.
retries := 1000
for {
n, err := file.Read(tun.rdBuff.data[:])
if err != nil {
tun.rdBuff.offset = 0
@ -266,20 +265,23 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
if tun.close {
return 0, os.ErrClosed
}
if retries > 0 && ok && pe.Err == windows.ERROR_OPERATION_ABORTED {
if retries > 0 && ok && (pe.Err == windows.ERROR_HANDLE_EOF || pe.Err == windows.ERROR_OPERATION_ABORTED) {
retries--
continue
}
if ok && pe.Err == windows.ERROR_HANDLE_EOF {
tun.closeTUN()
break
time.Sleep(time.Millisecond * 2)
continue
}
return 0, err
}
if n == 0 {
if retries == 0 {
return 0, io.ErrShortBuffer
}
retries--
continue
}
tun.rdBuff.offset = 0
tun.rdBuff.avail = uint32(n)
break
}
}
}
@ -289,6 +291,11 @@ func (tun *NativeTun) Flush() error {
if tun.wrBuff.offset == 0 {
return nil
}
defer func() {
tun.wrBuff.packetNum = 0
tun.wrBuff.offset = 0
}()
retries := 1000
for {
// Get TUN data pipe.
@ -297,23 +304,22 @@ func (tun *NativeTun) Flush() error {
return err
}
// Flush write buffer.
retries := 1000
for {
_, err = file.Write(tun.wrBuff.data[:tun.wrBuff.offset])
tun.wrBuff.packetNum = 0
tun.wrBuff.offset = 0
if err != nil {
pe, ok := err.(*os.PathError)
if tun.close {
return os.ErrClosed
}
if retries > 0 && ok && pe.Err == windows.ERROR_OPERATION_ABORTED {
if retries > 0 && ok && pe.Err == windows.ERROR_OPERATION_ABORTED { // Adapter is paused or in low-power state.
retries--
time.Sleep(time.Millisecond * 2)
continue
}
if ok && pe.Err == windows.ERROR_HANDLE_EOF {
if retries > 0 && ok && pe.Err == windows.ERROR_HANDLE_EOF { // Adapter is going down.
retries--
tun.closeTUN()
time.Sleep(time.Millisecond * 2)
break
}
return err