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tun: freebsd: remove horrific hack for getting tunnel name

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As of FreeBSD 12.1, there's TUNGIFNAME.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2021-04-18 20:26:32 -06:00
parent b0e5b19969
commit 3d3e30beb8
1 changed files with 13 additions and 84 deletions
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97
tun/tun_freebsd.go
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@ -6,7 +6,6 @@
package tun
import (
"bytes"
"errors"
"fmt"
"net"
@ -19,12 +18,10 @@ import (
"golang.org/x/sys/unix"
)
// _TUNSIFHEAD, value derived from sys/net/{if_tun,ioccom}.h
// const _TUNSIFHEAD = ((0x80000000) | (((4) & ((1 << 13) - 1) ) << 16) | (uint32(byte('t')) << 8) | (96))
const (
_TUNSIFHEAD = 0x80047460
_TUNSIFMODE = 0x8004745e
_TUNSIFPID = 0x2000745f
_TUNGIFNAME = 0x4020745d
)
// TODO: move into x/sys/unix
@ -40,6 +37,12 @@ const _IFSTATMAX = 800
const SIZEOF_UINTPTR = 4 << (^uintptr(0) >> 32 & 1)
// structure for iface requests for just the name
type ifreq_name struct {
Name [unix.IFNAMSIZ]byte
Pad0 [16]byte
}
// structure for iface requests with a pointer
type ifreq_ptr struct {
Name [unix.IFNAMSIZ]byte
@ -54,12 +57,6 @@ type ifreq_mtu struct {
Pad0 [12]byte
}
// Structure for interface status request ioctl
type ifstat struct {
IfsName [unix.IFNAMSIZ]byte
Ascii [_IFSTATMAX]byte
}
// Structures for nd6 flag manipulation
type in6_ndireq struct {
Name [unix.IFNAMSIZ]byte
@ -110,10 +107,10 @@ func (tun *NativeTun) routineRouteListener(tunIfindex int) {
continue
}
if data[3 /* type */] != unix.RTM_IFINFO {
if data[3 /* type */ ] != unix.RTM_IFINFO {
continue
}
ifindex := int(*(*uint16)(unsafe.Pointer(&data[12 /* ifindex */])))
ifindex := int(*(*uint16)(unsafe.Pointer(&data[12 /* ifindex */ ])))
if ifindex != tunIfindex {
continue
}
@ -143,80 +140,12 @@ func (tun *NativeTun) routineRouteListener(tunIfindex int) {
}
func tunName(fd uintptr) (string, error) {
// Terrible hack to make up for freebsd not having a TUNGIFNAME
// First, make sure the tun pid matches this proc's pid
_, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(fd),
uintptr(_TUNSIFPID),
uintptr(0),
)
if errno != 0 {
return "", fmt.Errorf("failed to set tun device PID: %s", errno.Error())
}
// Open iface control socket
confd, err := unix.Socket(
unix.AF_INET,
unix.SOCK_DGRAM,
0,
)
if err != nil {
var ifreq ifreq_name
_, _, err := unix.Syscall(unix.SYS_IOCTL, fd, _TUNGIFNAME, uintptr(unsafe.Pointer(&ifreq)))
if err != 0 {
return "", err
}
defer unix.Close(confd)
procPid := os.Getpid()
// Try to find interface with matching PID
for i := 1; ; i++ {
iface, _ := net.InterfaceByIndex(i)
if err != nil || iface == nil {
break
}
// Structs for getting data in and out of SIOCGIFSTATUS ioctl
var ifstatus ifstat
copy(ifstatus.IfsName[:], iface.Name)
// Make the syscall to get the status string
_, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(confd),
uintptr(unix.SIOCGIFSTATUS),
uintptr(unsafe.Pointer(&ifstatus)),
)
if errno != 0 {
continue
}
nullStr := ifstatus.Ascii[:]
i := bytes.IndexByte(nullStr, 0)
if i < 1 {
continue
}
statStr := string(nullStr[:i])
var pidNum int = 0
// Finally get the owning PID
// Format string taken from sys/net/if_tun.c
_, err := fmt.Sscanf(statStr, "\tOpened by PID %d\n", &pidNum)
if err != nil {
continue
}
if pidNum == procPid {
return iface.Name, nil
}
}
return "", nil
return unix.ByteSliceToString(ifreq.Name[:]), nil
}
// Destroy a named system interface