mirror of
https://github.com/NotAShelf/mdlinkt.git
synced 2024-11-30 00:56:46 +00:00
142 lines
4.3 KiB
Go
142 lines
4.3 KiB
Go
// Copyright 2021 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
//go:build linux
|
|
|
|
package unix
|
|
|
|
import (
|
|
"unsafe"
|
|
)
|
|
|
|
// Helpers for dealing with ifreq since it contains a union and thus requires a
|
|
// lot of unsafe.Pointer casts to use properly.
|
|
|
|
// An Ifreq is a type-safe wrapper around the raw ifreq struct. An Ifreq
|
|
// contains an interface name and a union of arbitrary data which can be
|
|
// accessed using the Ifreq's methods. To create an Ifreq, use the NewIfreq
|
|
// function.
|
|
//
|
|
// Use the Name method to access the stored interface name. The union data
|
|
// fields can be get and set using the following methods:
|
|
// - Uint16/SetUint16: flags
|
|
// - Uint32/SetUint32: ifindex, metric, mtu
|
|
type Ifreq struct{ raw ifreq }
|
|
|
|
// NewIfreq creates an Ifreq with the input network interface name after
|
|
// validating the name does not exceed IFNAMSIZ-1 (trailing NULL required)
|
|
// bytes.
|
|
func NewIfreq(name string) (*Ifreq, error) {
|
|
// Leave room for terminating NULL byte.
|
|
if len(name) >= IFNAMSIZ {
|
|
return nil, EINVAL
|
|
}
|
|
|
|
var ifr ifreq
|
|
copy(ifr.Ifrn[:], name)
|
|
|
|
return &Ifreq{raw: ifr}, nil
|
|
}
|
|
|
|
// TODO(mdlayher): get/set methods for hardware address sockaddr, char array, etc.
|
|
|
|
// Name returns the interface name associated with the Ifreq.
|
|
func (ifr *Ifreq) Name() string {
|
|
return ByteSliceToString(ifr.raw.Ifrn[:])
|
|
}
|
|
|
|
// According to netdevice(7), only AF_INET addresses are returned for numerous
|
|
// sockaddr ioctls. For convenience, we expose these as Inet4Addr since the Port
|
|
// field and other data is always empty.
|
|
|
|
// Inet4Addr returns the Ifreq union data from an embedded sockaddr as a C
|
|
// in_addr/Go []byte (4-byte IPv4 address) value. If the sockaddr family is not
|
|
// AF_INET, an error is returned.
|
|
func (ifr *Ifreq) Inet4Addr() ([]byte, error) {
|
|
raw := *(*RawSockaddrInet4)(unsafe.Pointer(&ifr.raw.Ifru[:SizeofSockaddrInet4][0]))
|
|
if raw.Family != AF_INET {
|
|
// Cannot safely interpret raw.Addr bytes as an IPv4 address.
|
|
return nil, EINVAL
|
|
}
|
|
|
|
return raw.Addr[:], nil
|
|
}
|
|
|
|
// SetInet4Addr sets a C in_addr/Go []byte (4-byte IPv4 address) value in an
|
|
// embedded sockaddr within the Ifreq's union data. v must be 4 bytes in length
|
|
// or an error will be returned.
|
|
func (ifr *Ifreq) SetInet4Addr(v []byte) error {
|
|
if len(v) != 4 {
|
|
return EINVAL
|
|
}
|
|
|
|
var addr [4]byte
|
|
copy(addr[:], v)
|
|
|
|
ifr.clear()
|
|
*(*RawSockaddrInet4)(
|
|
unsafe.Pointer(&ifr.raw.Ifru[:SizeofSockaddrInet4][0]),
|
|
) = RawSockaddrInet4{
|
|
// Always set IP family as ioctls would require it anyway.
|
|
Family: AF_INET,
|
|
Addr: addr,
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Uint16 returns the Ifreq union data as a C short/Go uint16 value.
|
|
func (ifr *Ifreq) Uint16() uint16 {
|
|
return *(*uint16)(unsafe.Pointer(&ifr.raw.Ifru[:2][0]))
|
|
}
|
|
|
|
// SetUint16 sets a C short/Go uint16 value as the Ifreq's union data.
|
|
func (ifr *Ifreq) SetUint16(v uint16) {
|
|
ifr.clear()
|
|
*(*uint16)(unsafe.Pointer(&ifr.raw.Ifru[:2][0])) = v
|
|
}
|
|
|
|
// Uint32 returns the Ifreq union data as a C int/Go uint32 value.
|
|
func (ifr *Ifreq) Uint32() uint32 {
|
|
return *(*uint32)(unsafe.Pointer(&ifr.raw.Ifru[:4][0]))
|
|
}
|
|
|
|
// SetUint32 sets a C int/Go uint32 value as the Ifreq's union data.
|
|
func (ifr *Ifreq) SetUint32(v uint32) {
|
|
ifr.clear()
|
|
*(*uint32)(unsafe.Pointer(&ifr.raw.Ifru[:4][0])) = v
|
|
}
|
|
|
|
// clear zeroes the ifreq's union field to prevent trailing garbage data from
|
|
// being sent to the kernel if an ifreq is reused.
|
|
func (ifr *Ifreq) clear() {
|
|
for i := range ifr.raw.Ifru {
|
|
ifr.raw.Ifru[i] = 0
|
|
}
|
|
}
|
|
|
|
// TODO(mdlayher): export as IfreqData? For now we can provide helpers such as
|
|
// IoctlGetEthtoolDrvinfo which use these APIs under the hood.
|
|
|
|
// An ifreqData is an Ifreq which carries pointer data. To produce an ifreqData,
|
|
// use the Ifreq.withData method.
|
|
type ifreqData struct {
|
|
name [IFNAMSIZ]byte
|
|
// A type separate from ifreq is required in order to comply with the
|
|
// unsafe.Pointer rules since the "pointer-ness" of data would not be
|
|
// preserved if it were cast into the byte array of a raw ifreq.
|
|
data unsafe.Pointer
|
|
// Pad to the same size as ifreq.
|
|
_ [len(ifreq{}.Ifru) - SizeofPtr]byte
|
|
}
|
|
|
|
// withData produces an ifreqData with the pointer p set for ioctls which require
|
|
// arbitrary pointer data.
|
|
func (ifr Ifreq) withData(p unsafe.Pointer) ifreqData {
|
|
return ifreqData{
|
|
name: ifr.raw.Ifrn,
|
|
data: p,
|
|
}
|
|
}
|