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Diffstat (limited to '')
-rw-r--r-- | dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/ifreq_linux.go | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/ifreq_linux.go b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/unix/ifreq_linux.go new file mode 100644 index 0000000..15721a5 --- /dev/null +++ b/dependencies/pkg/mod/golang.org/x/sys@v0.1.0/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, + } +} |