Golang syscall.ParseNetlinkMessage函数代码示例

func main() {
	sk := nlgo.NlSocketAlloc()
	if err := nlgo.GenlConnect(sk); err != nil {
		panic(err)
	} else if err := nlgo.GenlSendSimple(sk, nlgo.GENL_ID_CTRL, nlgo.CTRL_CMD_GETFAMILY, nlgo.CTRL_VERSION, syscall.NLM_F_DUMP); err != nil {
		panic(err)
	}
	nl80211 := nlgo.NlSocketAlloc()
	if err := nlgo.GenlConnect(nl80211); err != nil {
		panic(err)
	}

	data := make([]byte, syscall.Getpagesize())
	if n, _, _, _, err := syscall.Recvmsg(sk.Fd, data, nil, 0); err != nil {
		panic(err)
	} else if msgs, err := syscall.ParseNetlinkMessage(data[:n]); err != nil {
		log.Print("X", err)
	} else {
		for _, msg := range msgs {
			genl := *(*nlgo.GenlMsghdr)(unsafe.Pointer(&msg.Data[0]))
			if msg.Header.Type == nlgo.GENL_ID_CTRL && genl.Cmd == nlgo.CTRL_CMD_NEWFAMILY {
				if attr, err := nlgo.CtrlPolicy.Parse(msg.Data[nlgo.GENL_HDRLEN:]); err != nil {
					log.Print(err)
				} else if amap, ok := attr.(nlgo.AttrMap); !ok {
					log.Print(attr)
				} else if value := amap.Get(nlgo.CTRL_ATTR_FAMILY_NAME).(nlgo.NulString); string(value) == "nl80211" {
					log.Printf("%v", attr)
					for _, g := range amap.Get(nlgo.CTRL_ATTR_MCAST_GROUPS).(nlgo.AttrSlice).Slice() {
						group := g.Value.(nlgo.AttrMap)
						pid := group.Get(nlgo.CTRL_ATTR_MCAST_GRP_ID).(nlgo.U32)
						if err := nlgo.NlSocketAddMembership(nl80211, int(pid)); err != nil {
							log.Print(err)
						}
					}
				}
			} else {
				log.Print("UNKNOWN")
			}
		}
	}
	nlgo.NlSocketFree(sk)

	for {
		if n, _, _, _, err := syscall.Recvmsg(nl80211.Fd, data, nil, 0); err != nil {
			panic(err)
		} else if msgs, err := syscall.ParseNetlinkMessage(data[:n]); err != nil {
			log.Print("Y", err)
		} else {
			for _, msg := range msgs {
				genl := (*nlgo.GenlMsghdr)(unsafe.Pointer(&msg.Data[0]))
				if attr, err := nlgo.Nl80211Policy.Parse(msg.Data[nlgo.GENL_HDRLEN:]); err != nil {
					log.Print("Z", err)
				} else {
					log.Printf("NL80211_CMD_%s attrs=%s", nlgo.NL80211_CMD_itoa[genl.Cmd], attr)
				}
			}
		}
	}
}

func getDefaultRoute() (*syscall.NetlinkMessage, error) {
	dat, err := syscall.NetlinkRIB(syscall.RTM_GETROUTE, syscall.AF_UNSPEC)
	if err != nil {
		return nil, err
	}

	msgs, msgErr := syscall.ParseNetlinkMessage(dat)
	if msgErr != nil {
		return nil, msgErr
	}

	rtmsg := syscall.RtMsg{}
	for _, m := range msgs {
		if m.Header.Type != syscall.RTM_NEWROUTE {
			continue
		}
		buf := bytes.NewBuffer(m.Data[:syscall.SizeofRtMsg])
		if rerr := binary.Read(buf, binary.LittleEndian, &rtmsg); rerr != nil {
			continue
		}
		if rtmsg.Dst_len == 0 {
			// zero-length Dst_len implies default route
			return &m, nil
		}
	}

	return nil, errNoDefaultRoute
}

func TestParseNetlinkMessage(t *testing.T) {
	for i, b := range [][]byte{
		{103, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 5, 8, 0, 3,
			0, 8, 0, 6, 0, 0, 0, 0, 1, 63, 0, 10, 0, 69, 16, 0, 59, 39, 82, 64, 0, 64, 6, 21, 89, 127, 0, 0,
			1, 127, 0, 0, 1, 230, 228, 31, 144, 32, 186, 155, 211, 185, 151, 209, 179, 128, 24, 1, 86,
			53, 119, 0, 0, 1, 1, 8, 10, 0, 17, 234, 12, 0, 17, 189, 126, 107, 106, 108, 107, 106, 13, 10,
		},
		{106, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 3, 8, 0, 3,
			0, 8, 0, 6, 0, 0, 0, 0, 1, 66, 0, 10, 0, 69, 0, 0, 62, 230, 255, 64, 0, 64, 6, 85, 184, 127, 0, 0,
			1, 127, 0, 0, 1, 237, 206, 31, 144, 73, 197, 128, 65, 250, 60, 192, 97, 128, 24, 1, 86, 253, 21, 0,
			0, 1, 1, 8, 10, 0, 51, 106, 89, 0, 51, 102, 198, 108, 104, 106, 108, 107, 104, 108, 107, 104, 10,
		},
		{102, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 1, 8, 0, 3, 0,
			8, 0, 6, 0, 0, 0, 0, 1, 62, 0, 10, 0, 69, 0, 0, 58, 231, 2, 64, 0, 64, 6, 85, 185, 127, 0, 0, 1, 127,
			0, 0, 1, 237, 206, 31, 144, 73, 197, 128, 86, 250, 60, 192, 97, 128, 24, 1, 86, 104, 64, 0, 0, 1, 1, 8,
			10, 0, 52, 198, 200, 0, 51, 135, 232, 101, 115, 97, 103, 103, 10,
		},
	} {
		m, err := syscall.ParseNetlinkMessage(b)
		if err != syscall.EINVAL {
			t.Errorf("#%d: got %v; want EINVAL", i, err)
		}
		if m != nil {
			t.Errorf("#%d: got %v; want nil", i, m)
		}
	}
}

// getNeighbors sends a request to netlink to retrieve all neighbors using
// the specified address family.
func getNeighbors(family Family) ([]*Neighbor, error) {
	// Request neighbors belonging to a specific family from netlink
	tab, err := syscall.NetlinkRIB(syscall.RTM_GETNEIGH, int(family))
	if err != nil {
		return nil, os.NewSyscallError("netlink rib", err)
	}

	// Parse netlink information into individual messages
	msgs, err := syscall.ParseNetlinkMessage(tab)
	if err != nil {
		return nil, os.NewSyscallError("netlink message", err)
	}

	// Check messages for information
	var nn []*Neighbor
	for _, m := range msgs {
		// Ignore any messages which don't indicate a new neighbor
		if m.Header.Type != syscall.RTM_NEWNEIGH {
			continue
		}

		// Attempt to parse an individual neighbor from a message
		n, err := newNeighbor(&m)
		if err != nil {
			return nil, err
		}

		nn = append(nn, n)
	}

	return nn, nil
}

func getIface(idx uint32) (*syscall.NetlinkMessage, error) {
	dat, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
	if err != nil {
		return nil, err
	}

	msgs, msgErr := syscall.ParseNetlinkMessage(dat)
	if msgErr != nil {
		return nil, msgErr
	}

	ifaddrmsg := syscall.IfAddrmsg{}
	for _, m := range msgs {
		if m.Header.Type != syscall.RTM_NEWADDR {
			continue
		}
		buf := bytes.NewBuffer(m.Data[:syscall.SizeofIfAddrmsg])
		if rerr := binary.Read(buf, binary.LittleEndian, &ifaddrmsg); rerr != nil {
			continue
		}
		if ifaddrmsg.Index == idx {
			return &m, nil
		}
	}

	return nil, errNoDefaultRoute
}

// If the ifindex is zero, interfaceTable returns mappings of all
// network interfaces.  Otherwise it returns a mapping of a specific
// interface.
func interfaceTable(ifindex int) ([]Interface, error) { // 如果ifindex为0，返回所有网络接口
	tab, err := syscall.NetlinkRIB(syscall.RTM_GETLINK, syscall.AF_UNSPEC) // 获得netlink rib
	if err != nil {
		return nil, os.NewSyscallError("netlinkrib", err)
	}
	msgs, err := syscall.ParseNetlinkMessage(tab) // 解析netlink信息
	if err != nil {
		return nil, os.NewSyscallError("parsenetlinkmessage", err)
	}
	var ift []Interface
loop:
	for _, m := range msgs { // 遍历获取的netlink信息
		switch m.Header.Type {
		case syscall.NLMSG_DONE:
			break loop
		case syscall.RTM_NEWLINK:
			ifim := (*syscall.IfInfomsg)(unsafe.Pointer(&m.Data[0]))
			if ifindex == 0 || ifindex == int(ifim.Index) {
				attrs, err := syscall.ParseNetlinkRouteAttr(&m)
				if err != nil {
					return nil, os.NewSyscallError("parsenetlinkrouteattr", err)
				}
				ift = append(ift, *newLink(ifim, attrs)) // 加入到Interface Slice中
				if ifindex == int(ifim.Index) {
					break loop
				}
			}
		}
	}
	return ift, nil
}

// If the ifindex is zero, interfaceTable returns mappings of all
// network interfaces.  Otheriwse it returns a mapping of a specific
// interface.
func interfaceTable(ifindex int) ([]Interface, error) {
	tab, err := syscall.NetlinkRIB(syscall.RTM_GETLINK, syscall.AF_UNSPEC)
	if err != nil {
		return nil, os.NewSyscallError("netlink rib", err)
	}

	msgs, err := syscall.ParseNetlinkMessage(tab)
	if err != nil {
		return nil, os.NewSyscallError("netlink message", err)
	}

	var ift []Interface
	for _, m := range msgs {
		switch m.Header.Type {
		case syscall.NLMSG_DONE:
			goto done
		case syscall.RTM_NEWLINK:
			ifim := (*syscall.IfInfomsg)(unsafe.Pointer(&m.Data[0]))
			if ifindex == 0 || ifindex == int(ifim.Index) {
				attrs, err := syscall.ParseNetlinkRouteAttr(&m)
				if err != nil {
					return nil, os.NewSyscallError("netlink routeattr", err)
				}
				ifi := newLink(ifim, attrs)
				ift = append(ift, ifi)
			}
		}
	}
done:
	return ift, nil
}

func (w *Watcher) readAllEvents() {
	buf := make([]byte, syscall.Getpagesize())

	listener, _ := w.listener.(*netlinkListener)

	for {
		if w.isDone() {
			return
		}

		nr, _, err := syscall.Recvfrom(listener.sock, buf, 0)

		if err != nil {
			w.Error <- err
			continue
		}
		if nr < syscall.NLMSG_HDRLEN {
			w.Error <- syscall.EINVAL
			continue
		}

		msgs, _ := syscall.ParseNetlinkMessage(buf[:nr])

		for _, m := range msgs {
			if m.Header.Type == syscall.NLMSG_DONE {
				w.handleEventAll(m.Data)
			}
		}
	}
}

// If the ifindex is zero, interfaceAddrTable returns addresses
// for all network interfaces.  Otherwise it returns addresses
// for a specific interface.
func interfaceAddrTable(ifindex int) ([]Addr, os.Error) {
	var (
		tab  []byte
		e    int
		err  os.Error
		ifat []Addr
		msgs []syscall.NetlinkMessage
	)

	tab, e = syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
	if e != 0 {
		return nil, os.NewSyscallError("netlink rib", e)
	}

	msgs, e = syscall.ParseNetlinkMessage(tab)
	if e != 0 {
		return nil, os.NewSyscallError("netlink message", e)
	}

	ifat, err = addrTable(msgs, ifindex)
	if err != nil {
		return nil, err
	}

	return ifat, nil
}

func (nl *NetlinkSocket) RecvMessages(sz, sockflags int) ([]NetlinkMessage, error) {
	buf := make([]byte, sz)

	rsz, _, err := syscall.Recvfrom(nl.sfd, buf, sockflags)
	if err != nil {
		return nil, err
	}

	if rsz < syscall.NLMSG_HDRLEN {
		return nil, syscall.EINVAL
	}

	msgList, err := syscall.ParseNetlinkMessage(buf[:rsz])
	if err != nil {
		return nil, err
	}

	ret := []NetlinkMessage{}

	for _, msg := range msgList {
		msg := NetlinkMessage(msg)
		logf("received: %+v\n", msg)
		ret = append(ret, msg)
	}

	return ret, nil
}

func TestSocketPacketConn(t *testing.T) {
	s, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_RAW, syscall.NETLINK_ROUTE)
	if err != nil {
		t.Fatal(err)
	}
	lsa := syscall.SockaddrNetlink{Family: syscall.AF_NETLINK}
	if err := syscall.Bind(s, &lsa); err != nil {
		syscall.Close(s)
		t.Fatal(err)
	}
	f := os.NewFile(uintptr(s), "netlink")
	c, err := SocketPacketConn(f, &netlinkAddr{})
	f.Close()
	if err != nil {
		t.Fatal(err)
	}
	defer c.Close()

	const N = 3
	var wg sync.WaitGroup
	wg.Add(2 * N)
	dst := &netlinkAddr{PID: 0}
	for i := 0; i < N; i++ {
		go func() {
			defer wg.Done()
			l := syscall.NLMSG_HDRLEN + syscall.SizeofRtGenmsg
			b := make([]byte, l)
			*(*uint32)(unsafe.Pointer(&b[0:4][0])) = uint32(l)
			*(*uint16)(unsafe.Pointer(&b[4:6][0])) = uint16(syscall.RTM_GETLINK)
			*(*uint16)(unsafe.Pointer(&b[6:8][0])) = uint16(syscall.NLM_F_DUMP | syscall.NLM_F_REQUEST)
			*(*uint32)(unsafe.Pointer(&b[8:12][0])) = uint32(1)
			*(*uint32)(unsafe.Pointer(&b[12:16][0])) = uint32(0)
			b[16] = byte(syscall.AF_UNSPEC)
			if _, err := c.WriteTo(b, dst); err != nil {
				t.Error(err)
				return
			}
		}()
	}
	for i := 0; i < N; i++ {
		go func() {
			defer wg.Done()
			b := make([]byte, os.Getpagesize())
			n, _, err := c.ReadFrom(b)
			if err != nil {
				t.Error(err)
				return
			}
			if _, err := syscall.ParseNetlinkMessage(b[:n]); err != nil {
				t.Error(err)
				return
			}
		}()
	}
	wg.Wait()
}

func NewRtHub() (*RtHub, error) {
	self := &RtHub{
		sock:      NlSocketAlloc(),
		lock:      &sync.Mutex{},
		unilock:   &sync.Mutex{},
		multicast: make(map[uint32][]NetlinkListener),
	}
	if err := NlConnect(self.sock, syscall.NETLINK_ROUTE); err != nil {
		NlSocketFree(self.sock)
		return nil, err
	}
	go func() {
		for {
			buf := make([]byte, syscall.Getpagesize())
			if n, _, err := syscall.Recvfrom(self.sock.Fd, buf, syscall.MSG_TRUNC); err != nil {
				if e, ok := err.(syscall.Errno); ok && e.Temporary() {
					continue
				}
				break
			} else if msgs, err := syscall.ParseNetlinkMessage(buf[:n]); err != nil {
				break
			} else {
				for _, msg := range msgs {
					multi := func() []NetlinkListener {
						self.lock.Lock()
						defer self.lock.Unlock()

						var ret []NetlinkListener
						for _, s := range self.multicast {
							ret = append(ret, s...)
						}
						return ret
					}()
					if msg.Header.Seq == self.uniseq {
						if self.unicast != nil {
							self.unicast.NetlinkListen(msg)
						}
						switch msg.Header.Type {
						case syscall.NLMSG_DONE, syscall.NLMSG_ERROR:
							self.unilock.Unlock()
						}
					}
					if msg.Header.Seq == 0 {
						for _, proc := range multi {
							proc.NetlinkListen(msg)
						}
					}
				}
			}
		}
		log.Print("rt hub loop exit")
	}()
	return self, nil
}

func (s *NetlinkSocket) Receive() ([]syscall.NetlinkMessage, error) {
	rb := make([]byte, syscall.Getpagesize())
	nr, _, err := syscall.Recvfrom(s.fd, rb, 0)
	if err != nil {
		return nil, err
	}
	if nr < syscall.NLMSG_HDRLEN {
		return nil, ErrShortResponse
	}
	rb = rb[:nr]
	return syscall.ParseNetlinkMessage(rb)
}

// If the ifindex is zero, interfaceAddrTable returns addresses
// for all network interfaces.  Otherwise it returns addresses
// for a specific interface.
func interfaceAddrTable(ifindex int) ([]Addr, os.Error) {
	var (
		tab   []byte
		e     int
		err   os.Error
		ifat4 []Addr
		ifat6 []Addr
		msgs4 []syscall.NetlinkMessage
		msgs6 []syscall.NetlinkMessage
	)

	tab, e = syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_INET)
	if e != 0 {
		return nil, os.NewSyscallError("netlink rib", e)
	}
	msgs4, e = syscall.ParseNetlinkMessage(tab)
	if e != 0 {
		return nil, os.NewSyscallError("netlink message", e)
	}
	ifat4, err = addrTable(msgs4, ifindex)
	if err != nil {
		return nil, err
	}

	tab, e = syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_INET6)
	if e != 0 {
		return nil, os.NewSyscallError("netlink rib", e)
	}
	msgs6, e = syscall.ParseNetlinkMessage(tab)
	if e != 0 {
		return nil, os.NewSyscallError("netlink message", e)
	}
	ifat6, err = addrTable(msgs6, ifindex)
	if err != nil {
		return nil, err
	}

	return append(ifat4, ifat6...), nil
}

// genl_ctrl_probe_by_name is not exposed in the original libnl
func GenlCtrlProbeByName(sk *NlSock, name string) (AttrMap, error) {
	if err := GenlSendSimple(sk, GENL_ID_CTRL, CTRL_CMD_GETFAMILY, CTRL_VERSION, syscall.NLM_F_DUMP); err != nil {
		return AttrMap{}, err
	}
	var ret AttrMap
	err := func() error {
		for {
			buf := make([]byte, syscall.Getpagesize())
			if nn, _, err := syscall.Recvfrom(sk.Fd, buf, syscall.MSG_TRUNC); err != nil {
				return err
			} else if nn > len(buf) {
				return NLE_MSG_TRUNC
			} else {
				buf = buf[:nn]
			}
			if msgs, err := syscall.ParseNetlinkMessage(buf); err != nil {
				return err
			} else {
				for _, msg := range msgs {
					switch msg.Header.Type {
					case GENL_ID_CTRL:
						genl := (*GenlMsghdr)(unsafe.Pointer(&msg.Data[0]))
						switch genl.Cmd {
						case CTRL_CMD_NEWFAMILY:
							if attrs, err := CtrlPolicy.Parse(msg.Data[GENL_HDRLEN:]); err != nil {
								return err
							} else if info, ok := attrs.(AttrMap); !ok {
								// shold not happen
							} else if value := info.Get(CTRL_ATTR_FAMILY_NAME); value == nil {
								// should not happen by kernel
							} else if string(value.(NulString)) == name {
								ret = info
							}
						default:
							return fmt.Errorf("unexpected command")
						}
					case syscall.NLMSG_DONE:
						return nil
					case syscall.NLMSG_ERROR:
						return fmt.Errorf("NlMsgerr=%s", (*syscall.NlMsgerr)(unsafe.Pointer(&msg.Data[0])))
					default:
						return fmt.Errorf("unexpected NlMsghdr=%s", msg.Header)
					}
				}
			}
		}
	}()
	return ret, err
}