Golang syscall.NetlinkRIB函数代码示例

// 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
}

// 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 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 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, 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
}

// 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
}

// 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, error) {
	tab, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, 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)
	}
	ifat, err := addrTable(msgs, ifindex)
	if err != nil {
		return nil, err
	}
	return ifat, nil
}

// If the ifi is nil, interfaceAddrTable returns addresses for all
// network interfaces.  Otherwise it returns addresses for a specific
// interface.
func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
	tab, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
	if err != nil {
		return nil, os.NewSyscallError("netlinkrib", err)
	}
	msgs, err := syscall.ParseNetlinkMessage(tab)
	if err != nil {
		return nil, os.NewSyscallError("parsenetlinkmessage", err)
	}
	var ift []Interface
	if ifi == nil {
		var err error
		ift, err = interfaceTable(0)
		if err != nil {
			return nil, err
		}
	}
	ifat, err := addrTable(ift, ifi, msgs)
	if err != nil {
		return nil, err
	}
	return ifat, nil
}

func find_gateway(ip_mask *net.IPNet) (ip net.IP, dev string, err error) {
	buf, err := syscall.NetlinkRIB(syscall.RTM_GETROUTE, syscall.AF_INET)
	if err != nil {
		log.Println("Failed to open netlink:", err)
		return
	}
	msgs, err := syscall.ParseNetlinkMessage(buf)
	if err != nil {
		log.Println("Failed to parse nl msg:", err)
		return
	}
	var def route
	set := false
	var once sync.Once
loop:
	for _, m := range msgs {
		switch m.Header.Type {
		case syscall.NLMSG_DONE:
			break loop
		case syscall.RTM_NEWROUTE:
			// a route enrty
			var r route
			rtmsg := (*syscall.RtMsg)(unsafe.Pointer(&m.Data[0]))
			attrs, err := syscall.ParseNetlinkRouteAttr(&m)
			if err != nil {
				// err is shadowed
				log.Println("Failed to parse nl rtattr:", err)
				return ip, dev, err
			}
			// parse a route entry
			for _, a := range attrs {
				switch a.Attr.Type {
				case syscall.RTA_DST:
					addr := a.Value
					_, r.dst, err = net.ParseCIDR(fmt.Sprintf("%d.%d.%d.%d/%d", addr[0], addr[1], addr[2], addr[3], rtmsg.Dst_len))
					if err != nil {
						log.Println("Failed to parse ip addr:", err)
						return ip, dev, err
					}
				case syscall.RTA_GATEWAY:
					addr := a.Value
					r.gateway = net.IPv4(addr[0], addr[1], addr[2], addr[3])
				case syscall.RTA_OIF:
					r.if_index = int(a.Value[0])
				}
			}
			if r.dst == nil {
				once.Do(func() {
					def = r
					set = true
				})
			} else {
				if r.dst.Contains(ip_mask.IP) {
					ifce, err := net.InterfaceByIndex(r.if_index)
					if err != nil {
						log.Println("Failed to get interface by index:", err)
						return ip, dev, err
					}
					return r.gateway, ifce.Name, nil
				}

			}
		}
	}
	if set {
		ifce, err := net.InterfaceByIndex(def.if_index)
		if err != nil {
			log.Println("Failed to get interface by index:", err)
			return ip, dev, err
		}
		return def.gateway, ifce.Name, nil
	}
	err = fmt.Errorf("Route not found.")
	return
}

// New creates a new router object.  The router returned by New currently does
// not update its routes after construction... care should be taken for
// long-running programs to call New() regularly to take into account any
// changes to the routing table which have occurred since the last New() call.
func New() (Router, error) {
	rtr := &router{}
	tab, err := syscall.NetlinkRIB(syscall.RTM_GETROUTE, syscall.AF_UNSPEC)
	if err != nil {
		return nil, err
	}
	msgs, err := syscall.ParseNetlinkMessage(tab)
	if err != nil {
		return nil, err
	}
loop:
	for _, m := range msgs {
		switch m.Header.Type {
		case syscall.NLMSG_DONE:
			break loop
		case syscall.RTM_NEWROUTE:
			rt := (*routeInfoInMemory)(unsafe.Pointer(&m.Data[0]))
			routeInfo := rtInfo{}
			attrs, err := syscall.ParseNetlinkRouteAttr(&m)
			if err != nil {
				return nil, err
			}
			switch rt.Family {
			case syscall.AF_INET:
				rtr.v4 = append(rtr.v4, &routeInfo)
			case syscall.AF_INET6:
				rtr.v6 = append(rtr.v6, &routeInfo)
			default:
				continue loop
			}
			for _, attr := range attrs {
				switch attr.Attr.Type {
				case syscall.RTA_DST:
					routeInfo.Dst = &net.IPNet{
						IP:   net.IP(attr.Value),
						Mask: net.CIDRMask(int(rt.DstLen), len(attr.Value)*8),
					}
				case syscall.RTA_SRC:
					routeInfo.Src = &net.IPNet{
						IP:   net.IP(attr.Value),
						Mask: net.CIDRMask(int(rt.SrcLen), len(attr.Value)*8),
					}
				case syscall.RTA_GATEWAY:
					routeInfo.Gateway = net.IP(attr.Value)
				case syscall.RTA_PREFSRC:
					routeInfo.PrefSrc = net.IP(attr.Value)
				case syscall.RTA_IIF:
					routeInfo.InputIface = *(*uint32)(unsafe.Pointer(&attr.Value[0]))
				case syscall.RTA_OIF:
					routeInfo.OutputIface = *(*uint32)(unsafe.Pointer(&attr.Value[0]))
				case syscall.RTA_PRIORITY:
					routeInfo.Priority = *(*uint32)(unsafe.Pointer(&attr.Value[0]))
				}
			}
		}
	}
	sort.Sort(rtr.v4)
	sort.Sort(rtr.v6)
	ifaces, err := net.Interfaces()
	if err != nil {
		return nil, err
	}
	for i, iface := range ifaces {
		if i != iface.Index-1 {
			return nil, fmt.Errorf("out of order iface %d = %v", i, iface)
		}
		rtr.ifaces = append(rtr.ifaces, iface)
		var addrs ipAddrs
		ifaceAddrs, err := iface.Addrs()
		if err != nil {
			return nil, err
		}
		for _, addr := range ifaceAddrs {
			if inet, ok := addr.(*net.IPNet); ok {
				// Go has a nasty habit of giving you IPv4s as ::ffff:1.2.3.4 instead of 1.2.3.4.
				// We want to use mapped v4 addresses as v4 preferred addresses, never as v6
				// preferred addresses.
				if v4 := inet.IP.To4(); v4 != nil {
					if addrs.v4 == nil {
						addrs.v4 = v4
					}
				} else if addrs.v6 == nil {
					addrs.v6 = inet.IP
				}
			}
		}
		rtr.addrs = append(rtr.addrs, addrs)
	}
	return rtr, nil
}

// List all available routes on the system.
func Routes() ([]*Route, error) {
	var routes []*Route

	rib, err := syscall.NetlinkRIB(syscall.RTM_GETROUTE, syscall.AF_UNSPEC)
	if err != nil {
		return nil, fmt.Errorf("Could not retrieve RIB: %s", err)
	}

	msgs, err := syscall.ParseNetlinkMessage(rib)
	if err != nil {
		return nil, fmt.Errorf("Could not parse messages: %s")
	}

	for _, m := range msgs {
		if m.Header.Type == syscall.NLMSG_DONE {
			break
		}

		if m.Header.Type != syscall.RTM_NEWROUTE {
			continue
		}

		route := &Route{Default: true}

		rtmsg := (*rtmsg)(unsafe.Pointer(&m.Data[0]))

		attrs, err := syscall.ParseNetlinkRouteAttr(&m)
		if err != nil {
			return nil, fmt.Errorf("Could not parse attr: %s", err)
		}

		for _, a := range attrs {
			switch a.Attr.Type {
			case syscall.RTA_SRC:
				route.SrcNet = &net.IPNet{
					IP: net.IP(a.Value),
					Mask: net.CIDRMask(
						int(rtmsg.src_len),
						len(a.Value)*8,
					),
				}

			case syscall.RTA_DST:
				route.DstNet = &net.IPNet{
					IP: net.IP(a.Value),
					Mask: net.CIDRMask(
						int(rtmsg.dst_len),
						len(a.Value)*8,
					),
				}

				route.Default = false

			case syscall.RTA_GATEWAY:
				route.Gateway = net.IP(a.Value)

			case syscall.RTA_OIF:
				oif := *(*uint32)(unsafe.Pointer(&a.Value[0]))
				iface, err := net.InterfaceByIndex(int(oif))
				if err != nil {
				}

				route.Iface = iface

			case syscall.RTA_PRIORITY:
			}
		}

		routes = append(routes, route)
	}

	return routes, nil
}