Fix ioctl(2) code for OpenBSD (#1175)

This cleans up the mess to configure an IP address on a tun(4) device.

Handrolling a hardcoded ioctl(2) request is far from perfect, but Go
(golang.org/sys/unix) is to blame here.

Tested on OpenBSD 7.6 -current where yggdrasil now drives the interface
would use of ifconfig or other helpers.
This commit is contained in:
Klemens Nanni 2024-09-30 16:24:20 +03:00 committed by GitHub
parent 6d5243bd9a
commit ccda1075c0
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2 changed files with 124 additions and 2 deletions

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@ -1,5 +1,5 @@
//go:build openbsd || freebsd //go:build freebsd
// +build openbsd freebsd // +build freebsd
package tun package tun

122
src/tun/tun_openbsd.go Normal file
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@ -0,0 +1,122 @@
//go:build openbsd
// +build openbsd
package tun
import (
"fmt"
"net"
"syscall"
"unsafe"
"golang.org/x/sys/unix"
wgtun "golang.zx2c4.com/wireguard/tun"
)
const (
SIOCAIFADDR_IN6 = 0x8080691a
ND6_INFINITE_LIFETIME = 0xffffffff
)
type in6_addrlifetime struct {
ia6t_expire int64
ia6t_preferred int64
ia6t_vltime uint32
ia6t_pltime uint32
}
// Match types from the net package, effectively being [16]byte for IPv6 addresses.
type in6_addr [16]uint8
type sockaddr_in6 struct {
sin6_len uint8
sin6_family uint8
sin6_port uint16
sin6_flowinfo uint32
sin6_addr in6_addr
sin6_scope_id uint32
}
func (sa6 *sockaddr_in6) setSockaddr(addr [/*16*/]byte /* net.IP or net.IPMask */) {
sa6.sin6_len = uint8(unsafe.Sizeof(*sa6))
sa6.sin6_family = unix.AF_INET6
for i := range sa6.sin6_addr {
sa6.sin6_addr[i] = addr[i]
}
}
type in6_aliasreq struct {
ifra_name [syscall.IFNAMSIZ]byte
ifra_addr sockaddr_in6
ifra_dstaddr sockaddr_in6
ifra_prefixmask sockaddr_in6
ifra_flags int32
ifra_lifetime in6_addrlifetime
}
// Configures the TUN adapter with the correct IPv6 address and MTU.
func (tun *TunAdapter) setup(ifname string, addr string, mtu uint64) error {
iface, err := wgtun.CreateTUN(ifname, int(mtu))
if err != nil {
return fmt.Errorf("failed to create TUN: %w", err)
}
tun.iface = iface
if mtu, err := iface.MTU(); err == nil {
tun.mtu = getSupportedMTU(uint64(mtu))
} else {
tun.mtu = 0
}
if addr != "" {
return tun.setupAddress(addr)
}
return nil
}
// Configures the "utun" adapter from an existing file descriptor.
func (tun *TunAdapter) setupFD(fd int32, addr string, mtu uint64) error {
return fmt.Errorf("setup via FD not supported on this platform")
}
func (tun *TunAdapter) setupAddress(addr string) error {
var sfd int
var err error
ip, prefix, err := net.ParseCIDR(addr)
if err != nil {
tun.log.Errorf("Error in ParseCIDR: %v", err)
return err
}
// Create system socket
if sfd, err = unix.Socket(unix.AF_INET6, unix.SOCK_DGRAM, 0); err != nil {
tun.log.Printf("Create AF_INET6 socket failed: %v", err)
return err
}
// Friendly output
tun.log.Infof("Interface name: %s", tun.Name())
tun.log.Infof("Interface IPv6: %s", addr)
tun.log.Infof("Interface MTU: %d", tun.mtu)
// Create the address request
var ar in6_aliasreq
copy(ar.ifra_name[:], tun.Name())
ar.ifra_addr.setSockaddr(ip)
prefixmask := net.CIDRMask(prefix.Mask.Size())
ar.ifra_prefixmask.setSockaddr(prefixmask)
ar.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME
ar.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME
// Set the interface address
if err = unix.IoctlSetInt(sfd, SIOCAIFADDR_IN6, int(uintptr(unsafe.Pointer(&ar)))); err != nil {
tun.log.Errorf("Error in SIOCAIFADDR_IN6: %v", err)
return err
}
return nil
}