package netlink import ( "net" "syscall" "unsafe" "github.com/vishvananda/netlink/nl" ) const ( NDA_UNSPEC = iota NDA_DST NDA_LLADDR NDA_CACHEINFO NDA_PROBES NDA_VLAN NDA_PORT NDA_VNI NDA_IFINDEX NDA_MAX = NDA_IFINDEX ) // Neighbor Cache Entry States. const ( NUD_NONE = 0x00 NUD_INCOMPLETE = 0x01 NUD_REACHABLE = 0x02 NUD_STALE = 0x04 NUD_DELAY = 0x08 NUD_PROBE = 0x10 NUD_FAILED = 0x20 NUD_NOARP = 0x40 NUD_PERMANENT = 0x80 ) // Neighbor Flags const ( NTF_USE = 0x01 NTF_SELF = 0x02 NTF_MASTER = 0x04 NTF_PROXY = 0x08 NTF_ROUTER = 0x80 ) type Ndmsg struct { Family uint8 Index uint32 State uint16 Flags uint8 Type uint8 } func deserializeNdmsg(b []byte) *Ndmsg { var dummy Ndmsg return (*Ndmsg)(unsafe.Pointer(&b[0:unsafe.Sizeof(dummy)][0])) } func (msg *Ndmsg) Serialize() []byte { return (*(*[unsafe.Sizeof(*msg)]byte)(unsafe.Pointer(msg)))[:] } func (msg *Ndmsg) Len() int { return int(unsafe.Sizeof(*msg)) } // NeighAdd will add an IP to MAC mapping to the ARP table // Equivalent to: `ip neigh add ....` func NeighAdd(neigh *Neigh) error { return neighAdd(neigh, syscall.NLM_F_CREATE|syscall.NLM_F_EXCL) } // NeighSet will add or replace an IP to MAC mapping to the ARP table // Equivalent to: `ip neigh replace....` func NeighSet(neigh *Neigh) error { return neighAdd(neigh, syscall.NLM_F_CREATE|syscall.NLM_F_REPLACE) } // NeighAppend will append an entry to FDB // Equivalent to: `bridge fdb append...` func NeighAppend(neigh *Neigh) error { return neighAdd(neigh, syscall.NLM_F_CREATE|syscall.NLM_F_APPEND) } func neighAdd(neigh *Neigh, mode int) error { req := nl.NewNetlinkRequest(syscall.RTM_NEWNEIGH, mode|syscall.NLM_F_ACK) return neighHandle(neigh, req) } // NeighDel will delete an IP address from a link device. // Equivalent to: `ip addr del $addr dev $link` func NeighDel(neigh *Neigh) error { req := nl.NewNetlinkRequest(syscall.RTM_DELNEIGH, syscall.NLM_F_ACK) return neighHandle(neigh, req) } func neighHandle(neigh *Neigh, req *nl.NetlinkRequest) error { var family int if neigh.Family > 0 { family = neigh.Family } else { family = nl.GetIPFamily(neigh.IP) } msg := Ndmsg{ Family: uint8(family), Index: uint32(neigh.LinkIndex), State: uint16(neigh.State), Type: uint8(neigh.Type), Flags: uint8(neigh.Flags), } req.AddData(&msg) ipData := neigh.IP.To4() if ipData == nil { ipData = neigh.IP.To16() } dstData := nl.NewRtAttr(NDA_DST, ipData) req.AddData(dstData) hwData := nl.NewRtAttr(NDA_LLADDR, []byte(neigh.HardwareAddr)) req.AddData(hwData) _, err := req.Execute(syscall.NETLINK_ROUTE, 0) return err } // NeighList gets a list of IP-MAC mappings in the system (ARP table). // Equivalent to: `ip neighbor show`. // The list can be filtered by link and ip family. func NeighList(linkIndex, family int) ([]Neigh, error) { req := nl.NewNetlinkRequest(syscall.RTM_GETNEIGH, syscall.NLM_F_DUMP) msg := Ndmsg{ Family: uint8(family), Index: uint32(linkIndex), } req.AddData(&msg) msgs, err := req.Execute(syscall.NETLINK_ROUTE, syscall.RTM_NEWNEIGH) if err != nil { return nil, err } var res []Neigh for _, m := range msgs { ndm := deserializeNdmsg(m) if linkIndex != 0 && int(ndm.Index) != linkIndex { // Ignore messages from other interfaces continue } neigh, err := NeighDeserialize(m) if err != nil { continue } res = append(res, *neigh) } return res, nil } func NeighDeserialize(m []byte) (*Neigh, error) { msg := deserializeNdmsg(m) neigh := Neigh{ LinkIndex: int(msg.Index), Family: int(msg.Family), State: int(msg.State), Type: int(msg.Type), Flags: int(msg.Flags), } attrs, err := nl.ParseRouteAttr(m[msg.Len():]) if err != nil { return nil, err } for _, attr := range attrs { switch attr.Attr.Type { case NDA_DST: neigh.IP = net.IP(attr.Value) case NDA_LLADDR: neigh.HardwareAddr = net.HardwareAddr(attr.Value) } } return &neigh, nil }