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comparison vendor/golang.org/x/sys/unix/ifreq_linux.go @ 66:787b5ee0289d draft

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Use vendored modules Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>
author yakumo.izuru
date Sun, 23 Jul 2023 13:18:53 +0000
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65:6d985efa0f7a 66:787b5ee0289d
1 // Copyright 2021 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 //go:build linux
6 // +build linux
7
8 package unix
9
10 import (
11 "unsafe"
12 )
13
14 // Helpers for dealing with ifreq since it contains a union and thus requires a
15 // lot of unsafe.Pointer casts to use properly.
16
17 // An Ifreq is a type-safe wrapper around the raw ifreq struct. An Ifreq
18 // contains an interface name and a union of arbitrary data which can be
19 // accessed using the Ifreq's methods. To create an Ifreq, use the NewIfreq
20 // function.
21 //
22 // Use the Name method to access the stored interface name. The union data
23 // fields can be get and set using the following methods:
24 // - Uint16/SetUint16: flags
25 // - Uint32/SetUint32: ifindex, metric, mtu
26 type Ifreq struct{ raw ifreq }
27
28 // NewIfreq creates an Ifreq with the input network interface name after
29 // validating the name does not exceed IFNAMSIZ-1 (trailing NULL required)
30 // bytes.
31 func NewIfreq(name string) (*Ifreq, error) {
32 // Leave room for terminating NULL byte.
33 if len(name) >= IFNAMSIZ {
34 return nil, EINVAL
35 }
36
37 var ifr ifreq
38 copy(ifr.Ifrn[:], name)
39
40 return &Ifreq{raw: ifr}, nil
41 }
42
43 // TODO(mdlayher): get/set methods for hardware address sockaddr, char array, etc.
44
45 // Name returns the interface name associated with the Ifreq.
46 func (ifr *Ifreq) Name() string {
47 return ByteSliceToString(ifr.raw.Ifrn[:])
48 }
49
50 // According to netdevice(7), only AF_INET addresses are returned for numerous
51 // sockaddr ioctls. For convenience, we expose these as Inet4Addr since the Port
52 // field and other data is always empty.
53
54 // Inet4Addr returns the Ifreq union data from an embedded sockaddr as a C
55 // in_addr/Go []byte (4-byte IPv4 address) value. If the sockaddr family is not
56 // AF_INET, an error is returned.
57 func (ifr *Ifreq) Inet4Addr() ([]byte, error) {
58 raw := *(*RawSockaddrInet4)(unsafe.Pointer(&ifr.raw.Ifru[:SizeofSockaddrInet4][0]))
59 if raw.Family != AF_INET {
60 // Cannot safely interpret raw.Addr bytes as an IPv4 address.
61 return nil, EINVAL
62 }
63
64 return raw.Addr[:], nil
65 }
66
67 // SetInet4Addr sets a C in_addr/Go []byte (4-byte IPv4 address) value in an
68 // embedded sockaddr within the Ifreq's union data. v must be 4 bytes in length
69 // or an error will be returned.
70 func (ifr *Ifreq) SetInet4Addr(v []byte) error {
71 if len(v) != 4 {
72 return EINVAL
73 }
74
75 var addr [4]byte
76 copy(addr[:], v)
77
78 ifr.clear()
79 *(*RawSockaddrInet4)(
80 unsafe.Pointer(&ifr.raw.Ifru[:SizeofSockaddrInet4][0]),
81 ) = RawSockaddrInet4{
82 // Always set IP family as ioctls would require it anyway.
83 Family: AF_INET,
84 Addr: addr,
85 }
86
87 return nil
88 }
89
90 // Uint16 returns the Ifreq union data as a C short/Go uint16 value.
91 func (ifr *Ifreq) Uint16() uint16 {
92 return *(*uint16)(unsafe.Pointer(&ifr.raw.Ifru[:2][0]))
93 }
94
95 // SetUint16 sets a C short/Go uint16 value as the Ifreq's union data.
96 func (ifr *Ifreq) SetUint16(v uint16) {
97 ifr.clear()
98 *(*uint16)(unsafe.Pointer(&ifr.raw.Ifru[:2][0])) = v
99 }
100
101 // Uint32 returns the Ifreq union data as a C int/Go uint32 value.
102 func (ifr *Ifreq) Uint32() uint32 {
103 return *(*uint32)(unsafe.Pointer(&ifr.raw.Ifru[:4][0]))
104 }
105
106 // SetUint32 sets a C int/Go uint32 value as the Ifreq's union data.
107 func (ifr *Ifreq) SetUint32(v uint32) {
108 ifr.clear()
109 *(*uint32)(unsafe.Pointer(&ifr.raw.Ifru[:4][0])) = v
110 }
111
112 // clear zeroes the ifreq's union field to prevent trailing garbage data from
113 // being sent to the kernel if an ifreq is reused.
114 func (ifr *Ifreq) clear() {
115 for i := range ifr.raw.Ifru {
116 ifr.raw.Ifru[i] = 0
117 }
118 }
119
120 // TODO(mdlayher): export as IfreqData? For now we can provide helpers such as
121 // IoctlGetEthtoolDrvinfo which use these APIs under the hood.
122
123 // An ifreqData is an Ifreq which carries pointer data. To produce an ifreqData,
124 // use the Ifreq.withData method.
125 type ifreqData struct {
126 name [IFNAMSIZ]byte
127 // A type separate from ifreq is required in order to comply with the
128 // unsafe.Pointer rules since the "pointer-ness" of data would not be
129 // preserved if it were cast into the byte array of a raw ifreq.
130 data unsafe.Pointer
131 // Pad to the same size as ifreq.
132 _ [len(ifreq{}.Ifru) - SizeofPtr]byte
133 }
134
135 // withData produces an ifreqData with the pointer p set for ioctls which require
136 // arbitrary pointer data.
137 func (ifr Ifreq) withData(p unsafe.Pointer) ifreqData {
138 return ifreqData{
139 name: ifr.raw.Ifrn,
140 data: p,
141 }
142 }