1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
// Copyright 2011 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.
// Netlink sockets and messages
package syscall
import "unsafe"
// Round the length of a netlink message up to align it properly.
func nlmAlignOf(msglen int) int {
return (msglen + NLMSG_ALIGNTO - 1) & ^(NLMSG_ALIGNTO - 1)
}
// Round the length of a netlink route attribute up to align it
// properly.
func rtaAlignOf(attrlen int) int {
return (attrlen + RTA_ALIGNTO - 1) & ^(RTA_ALIGNTO - 1)
}
// NetlinkRouteRequest represents a request message to receive routing
// and link states from the kernel.
type NetlinkRouteRequest struct {
Header NlMsghdr
Data RtGenmsg
}
func (rr *NetlinkRouteRequest) toWireFormat() []byte {
b := make([]byte, rr.Header.Len)
*(*uint32)(unsafe.Pointer(&b[0:4][0])) = rr.Header.Len
*(*uint16)(unsafe.Pointer(&b[4:6][0])) = rr.Header.Type
*(*uint16)(unsafe.Pointer(&b[6:8][0])) = rr.Header.Flags
*(*uint32)(unsafe.Pointer(&b[8:12][0])) = rr.Header.Seq
*(*uint32)(unsafe.Pointer(&b[12:16][0])) = rr.Header.Pid
b[16] = byte(rr.Data.Family)
return b
}
func newNetlinkRouteRequest(proto, seq, family int) []byte {
rr := &NetlinkRouteRequest{}
rr.Header.Len = uint32(NLMSG_HDRLEN + SizeofRtGenmsg)
rr.Header.Type = uint16(proto)
rr.Header.Flags = NLM_F_DUMP | NLM_F_REQUEST
rr.Header.Seq = uint32(seq)
rr.Data.Family = uint8(family)
return rr.toWireFormat()
}
// NetlinkRIB returns routing information base, as known as RIB, which
// consists of network facility information, states and parameters.
func NetlinkRIB(proto, family int) ([]byte, error) {
s, err := Socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)
if err != nil {
return nil, err
}
defer Close(s)
lsa := &SockaddrNetlink{Family: AF_NETLINK}
if err := Bind(s, lsa); err != nil {
return nil, err
}
wb := newNetlinkRouteRequest(proto, 1, family)
if err := Sendto(s, wb, 0, lsa); err != nil {
return nil, err
}
var tab []byte
done:
for {
rb := make([]byte, Getpagesize())
nr, _, err := Recvfrom(s, rb, 0)
if err != nil {
return nil, err
}
if nr < NLMSG_HDRLEN {
return nil, EINVAL
}
rb = rb[:nr]
tab = append(tab, rb...)
msgs, err := ParseNetlinkMessage(rb)
if err != nil {
return nil, err
}
for _, m := range msgs {
lsa, err := Getsockname(s)
if err != nil {
return nil, err
}
switch v := lsa.(type) {
case *SockaddrNetlink:
if m.Header.Seq != 1 || m.Header.Pid != v.Pid {
return nil, EINVAL
}
default:
return nil, EINVAL
}
if m.Header.Type == NLMSG_DONE {
break done
}
if m.Header.Type == NLMSG_ERROR {
return nil, EINVAL
}
}
}
return tab, nil
}
// NetlinkMessage represents a netlink message.
type NetlinkMessage struct {
Header NlMsghdr
Data []byte
}
// ParseNetlinkMessage parses b as an array of netlink messages and
// returns the slice containing the NetlinkMessage structures.
func ParseNetlinkMessage(b []byte) ([]NetlinkMessage, error) {
var msgs []NetlinkMessage
for len(b) >= NLMSG_HDRLEN {
h, dbuf, dlen, err := netlinkMessageHeaderAndData(b)
if err != nil {
return nil, err
}
m := NetlinkMessage{Header: *h, Data: dbuf[:int(h.Len)-NLMSG_HDRLEN]}
msgs = append(msgs, m)
b = b[dlen:]
}
return msgs, nil
}
func netlinkMessageHeaderAndData(b []byte) (*NlMsghdr, []byte, int, error) {
h := (*NlMsghdr)(unsafe.Pointer(&b[0]))
if int(h.Len) < NLMSG_HDRLEN || int(h.Len) > len(b) {
return nil, nil, 0, EINVAL
}
return h, b[NLMSG_HDRLEN:], nlmAlignOf(int(h.Len)), nil
}
// NetlinkRouteAttr represents a netlink route attribute.
type NetlinkRouteAttr struct {
Attr RtAttr
Value []byte
}
// ParseNetlinkRouteAttr parses m's payload as an array of netlink
// route attributes and returns the slice containing the
// NetlinkRouteAttr structures.
func ParseNetlinkRouteAttr(m *NetlinkMessage) ([]NetlinkRouteAttr, error) {
var b []byte
switch m.Header.Type {
case RTM_NEWLINK, RTM_DELLINK:
b = m.Data[SizeofIfInfomsg:]
case RTM_NEWADDR, RTM_DELADDR:
b = m.Data[SizeofIfAddrmsg:]
case RTM_NEWROUTE, RTM_DELROUTE:
b = m.Data[SizeofRtMsg:]
default:
return nil, EINVAL
}
var attrs []NetlinkRouteAttr
for len(b) >= SizeofRtAttr {
a, vbuf, alen, err := netlinkRouteAttrAndValue(b)
if err != nil {
return nil, err
}
ra := NetlinkRouteAttr{Attr: *a, Value: vbuf[:int(a.Len)-SizeofRtAttr]}
attrs = append(attrs, ra)
b = b[alen:]
}
return attrs, nil
}
func netlinkRouteAttrAndValue(b []byte) (*RtAttr, []byte, int, error) {
a := (*RtAttr)(unsafe.Pointer(&b[0]))
if int(a.Len) < SizeofRtAttr || int(a.Len) > len(b) {
return nil, nil, 0, EINVAL
}
return a, b[SizeofRtAttr:], rtaAlignOf(int(a.Len)), nil
}
|
