feat(application): inital commit

vendor/golang.org/x/sys/unix/ifreq_linux.go

@@ -0,0 +1,142 @@
+// 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
+// +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,
+	}
+}