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// 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 the 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) {
var (
lsanl SockaddrNetlink
tab []byte
)
s, e := Socket(AF_NETLINK, SOCK_RAW, 0)
if e != nil {
return nil, e
}
defer Close(s)
lsanl.Family = AF_NETLINK
e = Bind(s, &lsanl)
if e != nil {
return nil, e
}
seq := 1
wb := newNetlinkRouteRequest(proto, seq, family)
e = Sendto(s, wb, 0, &lsanl)
if e != nil {
return nil, e
}
for {
var (
rb []byte
nr int
lsa Sockaddr
)
rb = make([]byte, Getpagesize())
nr, _, e = Recvfrom(s, rb, 0)
if e != nil {
return nil, e
}
if nr < NLMSG_HDRLEN {
return nil, EINVAL
}
rb = rb[:nr]
tab = append(tab, rb...)
msgs, _ := ParseNetlinkMessage(rb)
for _, m := range msgs {
if lsa, e = Getsockname(s); e != nil {
return nil, e
}
switch v := lsa.(type) {
case *SockaddrNetlink:
if m.Header.Seq != uint32(seq) || m.Header.Pid != v.Pid {
return nil, EINVAL
}
default:
return nil, EINVAL
}
if m.Header.Type == NLMSG_DONE {
goto done
}
if m.Header.Type == NLMSG_ERROR {
return nil, EINVAL
}
}
}
done:
return tab, nil
}
// NetlinkMessage represents the netlink message.
type NetlinkMessage struct {
Header NlMsghdr
Data []byte
}
// ParseNetlinkMessage parses buf as netlink messages and returns
// the slice containing the NetlinkMessage structs.
func ParseNetlinkMessage(buf []byte) ([]NetlinkMessage, error) {
var (
h *NlMsghdr
dbuf []byte
dlen int
e error
msgs []NetlinkMessage
)
for len(buf) >= NLMSG_HDRLEN {
h, dbuf, dlen, e = netlinkMessageHeaderAndData(buf)
if e != nil {
break
}
m := NetlinkMessage{}
m.Header = *h
m.Data = dbuf[:int(h.Len)-NLMSG_HDRLEN]
msgs = append(msgs, m)
buf = buf[dlen:]
}
return msgs, e
}
func netlinkMessageHeaderAndData(buf []byte) (*NlMsghdr, []byte, int, error) {
h := (*NlMsghdr)(unsafe.Pointer(&buf[0]))
if int(h.Len) < NLMSG_HDRLEN || int(h.Len) > len(buf) {
return nil, nil, 0, EINVAL
}
return h, buf[NLMSG_HDRLEN:], nlmAlignOf(int(h.Len)), nil
}
// NetlinkRouteAttr represents the netlink route attribute.
type NetlinkRouteAttr struct {
Attr RtAttr
Value []byte
}
// ParseNetlinkRouteAttr parses msg's payload as netlink route
// attributes and returns the slice containing the NetlinkRouteAttr
// structs.
func ParseNetlinkRouteAttr(msg *NetlinkMessage) ([]NetlinkRouteAttr, error) {
var (
buf []byte
a *RtAttr
alen int
vbuf []byte
e error
attrs []NetlinkRouteAttr
)
switch msg.Header.Type {
case RTM_NEWLINK, RTM_DELLINK:
buf = msg.Data[SizeofIfInfomsg:]
case RTM_NEWADDR, RTM_DELADDR:
buf = msg.Data[SizeofIfAddrmsg:]
case RTM_NEWROUTE, RTM_DELROUTE:
buf = msg.Data[SizeofRtMsg:]
default:
return nil, EINVAL
}
for len(buf) >= SizeofRtAttr {
a, vbuf, alen, e = netlinkRouteAttrAndValue(buf)
if e != nil {
break
}
ra := NetlinkRouteAttr{}
ra.Attr = *a
ra.Value = vbuf[:int(a.Len)-SizeofRtAttr]
attrs = append(attrs, ra)
buf = buf[alen:]
}
return attrs, nil
}
func netlinkRouteAttrAndValue(buf []byte) (*RtAttr, []byte, int, error) {
h := (*RtAttr)(unsafe.Pointer(&buf[0]))
if int(h.Len) < SizeofRtAttr || int(h.Len) > len(buf) {
return nil, nil, 0, EINVAL
}
return h, buf[SizeofRtAttr:], rtaAlignOf(int(h.Len)), nil
}
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