1 // Copyright 2011 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.
5 // Netlink sockets and messages
13 // Round the length of a netlink message up to align it properly.
14 func nlmAlignOf(msglen int) int {
15 return (msglen + NLMSG_ALIGNTO - 1) & ^(NLMSG_ALIGNTO - 1)
18 // Round the length of a netlink route attribute up to align it
20 func rtaAlignOf(attrlen int) int {
21 return (attrlen + RTA_ALIGNTO - 1) & ^(RTA_ALIGNTO - 1)
24 // NetlinkRouteRequest represents the request message to receive
25 // routing and link states from the kernel.
26 type NetlinkRouteRequest struct {
31 func (rr *NetlinkRouteRequest) toWireFormat() []byte {
32 b := make([]byte, rr.Header.Len)
33 *(*uint32)(unsafe.Pointer(&b[0:4][0])) = rr.Header.Len
34 *(*uint16)(unsafe.Pointer(&b[4:6][0])) = rr.Header.Type
35 *(*uint16)(unsafe.Pointer(&b[6:8][0])) = rr.Header.Flags
36 *(*uint32)(unsafe.Pointer(&b[8:12][0])) = rr.Header.Seq
37 *(*uint32)(unsafe.Pointer(&b[12:16][0])) = rr.Header.Pid
38 b[16] = byte(rr.Data.Family)
42 func newNetlinkRouteRequest(proto, seq, family int) []byte {
43 rr := &NetlinkRouteRequest{}
44 rr.Header.Len = uint32(NLMSG_HDRLEN + SizeofRtGenmsg)
45 rr.Header.Type = uint16(proto)
46 rr.Header.Flags = NLM_F_DUMP | NLM_F_REQUEST
47 rr.Header.Seq = uint32(seq)
48 rr.Data.Family = uint8(family)
49 return rr.toWireFormat()
52 // NetlinkRIB returns routing information base, as known as RIB,
53 // which consists of network facility information, states and
55 func NetlinkRIB(proto, family int) ([]byte, error) {
61 s, e := Socket(AF_NETLINK, SOCK_RAW, 0)
67 lsanl.Family = AF_NETLINK
74 wb := newNetlinkRouteRequest(proto, seq, family)
75 e = Sendto(s, wb, 0, &lsanl)
87 rb = make([]byte, Getpagesize())
88 nr, _, e = Recvfrom(s, rb, 0)
92 if nr < NLMSG_HDRLEN {
96 tab = append(tab, rb...)
98 msgs, _ := ParseNetlinkMessage(rb)
99 for _, m := range msgs {
100 if lsa, e = Getsockname(s); e != nil {
103 switch v := lsa.(type) {
104 case *SockaddrNetlink:
105 if m.Header.Seq != uint32(seq) || m.Header.Pid != v.Pid {
111 if m.Header.Type == NLMSG_DONE {
114 if m.Header.Type == NLMSG_ERROR {
124 // NetlinkMessage represents the netlink message.
125 type NetlinkMessage struct {
130 // ParseNetlinkMessage parses buf as netlink messages and returns
131 // the slice containing the NetlinkMessage structs.
132 func ParseNetlinkMessage(buf []byte) ([]NetlinkMessage, error) {
138 msgs []NetlinkMessage
141 for len(buf) >= NLMSG_HDRLEN {
142 h, dbuf, dlen, e = netlinkMessageHeaderAndData(buf)
146 m := NetlinkMessage{}
148 m.Data = dbuf[:int(h.Len)-NLMSG_HDRLEN]
149 msgs = append(msgs, m)
156 func netlinkMessageHeaderAndData(buf []byte) (*NlMsghdr, []byte, int, error) {
157 h := (*NlMsghdr)(unsafe.Pointer(&buf[0]))
158 if int(h.Len) < NLMSG_HDRLEN || int(h.Len) > len(buf) {
159 return nil, nil, 0, EINVAL
161 return h, buf[NLMSG_HDRLEN:], nlmAlignOf(int(h.Len)), nil
164 // NetlinkRouteAttr represents the netlink route attribute.
165 type NetlinkRouteAttr struct {
170 // ParseNetlinkRouteAttr parses msg's payload as netlink route
171 // attributes and returns the slice containing the NetlinkRouteAttr
173 func ParseNetlinkRouteAttr(msg *NetlinkMessage) ([]NetlinkRouteAttr, error) {
180 attrs []NetlinkRouteAttr
183 switch msg.Header.Type {
184 case RTM_NEWLINK, RTM_DELLINK:
185 buf = msg.Data[SizeofIfInfomsg:]
186 case RTM_NEWADDR, RTM_DELADDR:
187 buf = msg.Data[SizeofIfAddrmsg:]
188 case RTM_NEWROUTE, RTM_DELROUTE:
189 buf = msg.Data[SizeofRtMsg:]
194 for len(buf) >= SizeofRtAttr {
195 a, vbuf, alen, e = netlinkRouteAttrAndValue(buf)
199 ra := NetlinkRouteAttr{}
201 ra.Value = vbuf[:int(a.Len)-SizeofRtAttr]
202 attrs = append(attrs, ra)
209 func netlinkRouteAttrAndValue(buf []byte) (*RtAttr, []byte, int, error) {
210 h := (*RtAttr)(unsafe.Pointer(&buf[0]))
211 if int(h.Len) < SizeofRtAttr || int(h.Len) > len(buf) {
212 return nil, nil, 0, EINVAL
214 return h, buf[SizeofRtAttr:], rtaAlignOf(int(h.Len)), nil