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Merge pull request #255 from Arceliar/tunfix

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Fix panic when writing to closed tun (from race during shutdown)
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Arceliar 2018-12-16 18:35:21 -06:00 committed by GitHub
commit 575572d9a0
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1 changed files with 36 additions and 6 deletions
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34
src/yggdrasil/tun.go
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@ -5,6 +5,7 @@ package yggdrasil
import (
"bytes"
"errors"
"sync"
"time"
"github.com/songgao/packets/ethernet"
@ -24,6 +25,8 @@ type tunAdapter struct {
icmpv6 icmpv6
mtu int
iface *water.Interface
mutex sync.RWMutex // Protects the below
isOpen bool
}
// Gets the maximum supported MTU for the platform based on the defaults in
@ -50,8 +53,11 @@ func (tun *tunAdapter) start(ifname string, iftapmode bool, addr string, mtu int
if err := tun.setup(ifname, iftapmode, addr, mtu); err != nil {
return err
}
go func() { panic(tun.read()) }()
go func() { panic(tun.write()) }()
tun.mutex.Lock()
tun.isOpen = true
tun.mutex.Unlock()
go func() { tun.core.log.Println("WARNING: tun.read() exited with error:", tun.read()) }()
go func() { tun.core.log.Println("WARNING: tun.write() exited with error:", tun.write()) }()
if iftapmode {
go func() {
for {
@ -148,14 +154,28 @@ func (tun *tunAdapter) write() error {
len(data)) // Payload length
copy(frame[tun_ETHER_HEADER_LENGTH:], data[:])
if _, err := tun.iface.Write(frame); err != nil {
tun.mutex.RLock()
open := tun.isOpen
tun.mutex.RUnlock()
if !open {
return nil
} else {
panic(err)
}
}
}
} else {
if _, err := tun.iface.Write(data); err != nil {
tun.mutex.RLock()
open := tun.isOpen
tun.mutex.RUnlock()
if !open {
return nil
} else {
panic(err)
}
}
}
util.PutBytes(data)
}
}
@ -173,9 +193,16 @@ func (tun *tunAdapter) read() error {
for {
n, err := tun.iface.Read(buf)
if err != nil {
tun.mutex.RLock()
open := tun.isOpen
tun.mutex.RUnlock()
if !open {
return nil
} else {
// panic(err)
return err
}
}
o := 0
if tun.iface.IsTAP() {
o = tun_ETHER_HEADER_LENGTH
@ -202,6 +229,9 @@ func (tun *tunAdapter) read() error {
// process stops. Typically this operation will happen quickly, but on macOS
// it can block until a read operation is completed.
func (tun *tunAdapter) close() error {
tun.mutex.Lock()
tun.isOpen = false
tun.mutex.Unlock()
if tun.iface == nil {
return nil
}