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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.
// +build darwin dragonfly freebsd netbsd openbsd
// Routing sockets and messages
package syscall
import "unsafe"
// Round the length of a raw sockaddr up to align it properly.
func rsaAlignOf(salen int) int {
salign := sizeofPtr
// NOTE: It seems like 64-bit Darwin kernel still requires
// 32-bit aligned access to BSD subsystem. Also NetBSD 6
// kernel and beyond require 64-bit aligned access to routing
// facilities.
if darwin64Bit {
salign = 4
} else if netbsd32Bit {
salign = 8
}
if salen == 0 {
return salign
}
return (salen + salign - 1) & ^(salign - 1)
}
// RouteRIB returns routing information base, as known as RIB,
// which consists of network facility information, states and
// parameters.
func RouteRIB(facility, param int) ([]byte, error) {
mib := []_C_int{CTL_NET, AF_ROUTE, 0, 0, _C_int(facility), _C_int(param)}
// Find size.
n := uintptr(0)
if err := sysctl(mib, nil, &n, nil, 0); err != nil {
return nil, err
}
if n == 0 {
return nil, nil
}
tab := make([]byte, n)
if err := sysctl(mib, &tab[0], &n, nil, 0); err != nil {
return nil, err
}
return tab[:n], nil
}
// RoutingMessage represents a routing message.
type RoutingMessage interface {
sockaddr() []Sockaddr
}
const anyMessageLen = int(unsafe.Sizeof(anyMessage{}))
type anyMessage struct {
Msglen uint16
Version uint8
Type uint8
}
// RouteMessage represents a routing message containing routing
// entries.
type RouteMessage struct {
Header RtMsghdr
Data []byte
}
const rtaRtMask = RTA_DST | RTA_GATEWAY | RTA_NETMASK | RTA_GENMASK
func (m *RouteMessage) sockaddr() []Sockaddr {
var (
af int
sas [4]Sockaddr
)
b := m.Data[:]
for i := uint(0); i < RTAX_MAX; i++ {
if m.Header.Addrs&rtaRtMask&(1<<i) == 0 {
continue
}
rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
switch i {
case RTAX_DST, RTAX_GATEWAY:
sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
if err != nil {
return nil
}
if i == RTAX_DST {
af = int(rsa.Family)
}
sas[i] = sa
case RTAX_NETMASK, RTAX_GENMASK:
switch af {
case AF_INET:
rsa4 := (*RawSockaddrInet4)(unsafe.Pointer(&b[0]))
sa := new(SockaddrInet4)
for j := 0; rsa4.Len > 0 && j < int(rsa4.Len)-int(unsafe.Offsetof(rsa4.Addr)); j++ {
sa.Addr[j] = rsa4.Addr[j]
}
sas[i] = sa
case AF_INET6:
rsa6 := (*RawSockaddrInet6)(unsafe.Pointer(&b[0]))
sa := new(SockaddrInet6)
for j := 0; rsa6.Len > 0 && j < int(rsa6.Len)-int(unsafe.Offsetof(rsa6.Addr)); j++ {
sa.Addr[j] = rsa6.Addr[j]
}
sas[i] = sa
}
}
b = b[rsaAlignOf(int(rsa.Len)):]
}
return sas[:]
}
// InterfaceMessage represents a routing message containing
// network interface entries.
type InterfaceMessage struct {
Header IfMsghdr
Data []byte
}
func (m *InterfaceMessage) sockaddr() (sas []Sockaddr) {
if m.Header.Addrs&RTA_IFP == 0 {
return nil
}
sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(&m.Data[0])))
if err != nil {
return nil
}
return append(sas, sa)
}
// InterfaceAddrMessage represents a routing message containing
// network interface address entries.
type InterfaceAddrMessage struct {
Header IfaMsghdr
Data []byte
}
const rtaIfaMask = RTA_IFA | RTA_NETMASK | RTA_BRD
func (m *InterfaceAddrMessage) sockaddr() (sas []Sockaddr) {
if m.Header.Addrs&rtaIfaMask == 0 {
return nil
}
b := m.Data[:]
// We still see AF_UNSPEC in socket addresses on some
// platforms. To identify each address family correctly, we
// will use the address family of RTAX_NETMASK as a preferred
// one on the 32-bit NetBSD kernel, also use the length of
// RTAX_NETMASK socket address on the FreeBSD kernel.
preferredFamily := uint8(AF_UNSPEC)
for i := uint(0); i < RTAX_MAX; i++ {
if m.Header.Addrs&rtaIfaMask&(1<<i) == 0 {
continue
}
rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
switch i {
case RTAX_IFA:
if rsa.Family == AF_UNSPEC {
rsa.Family = preferredFamily
}
sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
if err != nil {
return nil
}
sas = append(sas, sa)
case RTAX_NETMASK:
switch rsa.Family {
case AF_UNSPEC:
switch rsa.Len {
case SizeofSockaddrInet4:
rsa.Family = AF_INET
case SizeofSockaddrInet6:
rsa.Family = AF_INET6
default:
rsa.Family = AF_INET // an old fashion, AF_UNSPEC means AF_INET
}
case AF_INET, AF_INET6:
preferredFamily = rsa.Family
default:
return nil
}
sa, err := anyToSockaddr((*RawSockaddrAny)(unsafe.Pointer(rsa)))
if err != nil {
return nil
}
sas = append(sas, sa)
case RTAX_BRD:
// nothing to do
}
b = b[rsaAlignOf(int(rsa.Len)):]
}
return sas
}
// ParseRoutingMessage parses b as routing messages and returns the
// slice containing the RoutingMessage interfaces.
func ParseRoutingMessage(b []byte) (msgs []RoutingMessage, err error) {
msgCount := 0
for len(b) >= anyMessageLen {
msgCount++
any := (*anyMessage)(unsafe.Pointer(&b[0]))
if any.Version != RTM_VERSION {
b = b[any.Msglen:]
continue
}
msgs = append(msgs, any.toRoutingMessage(b))
b = b[any.Msglen:]
}
// We failed to parse any of the messages - version mismatch?
if msgCount > 0 && len(msgs) == 0 {
return nil, EINVAL
}
return msgs, nil
}
// ParseRoutingMessage parses msg's payload as raw sockaddrs and
// returns the slice containing the Sockaddr interfaces.
func ParseRoutingSockaddr(msg RoutingMessage) (sas []Sockaddr, err error) {
return append(sas, msg.sockaddr()...), nil
}
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