193 lines
4.6 KiB
Go
193 lines
4.6 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin freebsd netbsd openbsd
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// Routing sockets and messages
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package syscall
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import "unsafe"
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// Round the length of a raw sockaddr up to align it properly.
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func rsaAlignOf(salen int) int {
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salign := sizeofPtr
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// NOTE: It seems like 64-bit Darwin kernel still requires 32-bit
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// aligned access to BSD subsystem.
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if darwinAMD64 {
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salign = 4
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}
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if salen == 0 {
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return salign
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}
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return (salen + salign - 1) & ^(salign - 1)
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}
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// RouteRIB returns routing information base, as known as RIB,
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// which consists of network facility information, states and
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// parameters.
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func RouteRIB(facility, param int) ([]byte, error) {
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mib := []_C_int{CTL_NET, AF_ROUTE, 0, 0, _C_int(facility), _C_int(param)}
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// Find size.
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n := uintptr(0)
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if err := sysctl(mib, nil, &n, nil, 0); err != nil {
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return nil, err
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}
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if n == 0 {
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return nil, nil
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}
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tab := make([]byte, n)
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if err := sysctl(mib, &tab[0], &n, nil, 0); err != nil {
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return nil, err
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}
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return tab[:n], nil
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}
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// RoutingMessage represents a routing message.
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type RoutingMessage interface {
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sockaddr() []Sockaddr
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}
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const anyMessageLen = int(unsafe.Sizeof(anyMessage{}))
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type anyMessage struct {
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Msglen uint16
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Version uint8
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Type uint8
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}
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// RouteMessage represents a routing message containing routing
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// entries.
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type RouteMessage struct {
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Header RtMsghdr
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Data []byte
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}
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const rtaRtMask = RTA_DST | RTA_GATEWAY | RTA_NETMASK | RTA_GENMASK
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func (m *RouteMessage) sockaddr() []Sockaddr {
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var (
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af int
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sas [4]Sockaddr
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)
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b := m.Data[:]
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for i := uint(0); i < RTAX_MAX; i++ {
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if m.Header.Addrs&rtaRtMask&(1<<i) == 0 {
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continue
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}
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rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
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switch i {
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case RTAX_DST, RTAX_GATEWAY:
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sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
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if err != nil {
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return nil
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}
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if i == RTAX_DST {
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af = int(rsa.Family)
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}
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sas[i] = sa
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case RTAX_NETMASK, RTAX_GENMASK:
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switch af {
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case AF_INET:
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rsa4 := (*RawSockaddrInet4)(unsafe.Pointer(&b[0]))
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sa := new(SockaddrInet4)
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for j := 0; rsa4.Len > 0 && j < int(rsa4.Len)-int(unsafe.Offsetof(rsa4.Addr)); j++ {
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sa.Addr[j] = rsa4.Addr[j]
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}
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sas[i] = sa
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case AF_INET6:
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rsa6 := (*RawSockaddrInet6)(unsafe.Pointer(&b[0]))
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sa := new(SockaddrInet6)
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for j := 0; rsa6.Len > 0 && j < int(rsa6.Len)-int(unsafe.Offsetof(rsa6.Addr)); j++ {
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sa.Addr[j] = rsa6.Addr[j]
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}
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sas[i] = sa
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}
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}
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b = b[rsaAlignOf(int(rsa.Len)):]
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}
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return sas[:]
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}
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// InterfaceMessage represents a routing message containing
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// network interface entries.
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type InterfaceMessage struct {
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Header IfMsghdr
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Data []byte
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}
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func (m *InterfaceMessage) sockaddr() (sas []Sockaddr) {
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if m.Header.Addrs&RTA_IFP == 0 {
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return nil
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}
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sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(&m.Data[0])))
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if err != nil {
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return nil
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}
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return append(sas, sa)
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}
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// InterfaceAddrMessage represents a routing message containing
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// network interface address entries.
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type InterfaceAddrMessage struct {
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Header IfaMsghdr
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Data []byte
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}
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const rtaIfaMask = RTA_IFA | RTA_NETMASK | RTA_BRD
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func (m *InterfaceAddrMessage) sockaddr() (sas []Sockaddr) {
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if m.Header.Addrs&rtaIfaMask == 0 {
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return nil
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}
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b := m.Data[:]
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for i := uint(0); i < RTAX_MAX; i++ {
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if m.Header.Addrs&rtaIfaMask&(1<<i) == 0 {
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continue
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}
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rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
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switch i {
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case RTAX_IFA:
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sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
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if err != nil {
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return nil
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}
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sas = append(sas, sa)
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case RTAX_NETMASK:
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if rsa.Family == AF_UNSPEC {
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rsa.Family = AF_INET // an old fasion, AF_UNSPEC means AF_INET
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}
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sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
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if err != nil {
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return nil
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}
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sas = append(sas, sa)
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case RTAX_BRD:
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// nothing to do
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}
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b = b[rsaAlignOf(int(rsa.Len)):]
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}
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return sas
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}
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// ParseRoutingMessage parses b as routing messages and returns the
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// slice containing the RoutingMessage interfaces.
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func ParseRoutingMessage(b []byte) (msgs []RoutingMessage, err error) {
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for len(b) >= anyMessageLen {
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any := (*anyMessage)(unsafe.Pointer(&b[0]))
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if any.Version != RTM_VERSION {
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return nil, EINVAL
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}
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msgs = append(msgs, any.toRoutingMessage(b))
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b = b[any.Msglen:]
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}
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return msgs, nil
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}
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// ParseRoutingMessage parses msg's payload as raw sockaddrs and
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// returns the slice containing the Sockaddr interfaces.
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func ParseRoutingSockaddr(msg RoutingMessage) (sas []Sockaddr, err error) {
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return append(sas, msg.sockaddr()...), nil
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}
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