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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
package syscall
import (
"runtime"
"unsafe"
)
var (
freebsdConfArch string // "machine $arch" line in kern.conftxt on freebsd
minRoutingSockaddrLen = rsaAlignOf(0)
)
// Round the length of a raw sockaddr up to align it properly.
func rsaAlignOf(salen int) int {
salign := sizeofPtr
if darwin64Bit {
// Darwin kernels require 32-bit aligned access to
// routing facilities.
salign = 4
} else if netbsd32Bit {
// NetBSD 6 and beyond kernels require 64-bit aligned
// access to routing facilities.
salign = 8
} else if runtime.GOOS == "freebsd" {
// In the case of kern.supported_archs="amd64 i386",
// we need to know the underlying kernel's
// architecture because the alignment for routing
// facilities are set at the build time of the kernel.
if freebsdConfArch == "amd64" {
salign = 8
}
}
if salen == 0 {
return salign
}
return (salen + salign - 1) & ^(salign - 1)
}
// parseSockaddrLink parses b as a datalink socket address.
func parseSockaddrLink(b []byte) (*SockaddrDatalink, error) {
sa, _, err := parseLinkLayerAddr(b[4:])
if err != nil {
return nil, err
}
rsa := (*RawSockaddrDatalink)(unsafe.Pointer(&b[0]))
sa.Len = rsa.Len
sa.Family = rsa.Family
sa.Index = rsa.Index
return sa, nil
}
// parseLinkLayerAddr parses b as a datalink socket address in
// conventional BSD kernel form.
func parseLinkLayerAddr(b []byte) (*SockaddrDatalink, int, error) {
// The encoding looks like the following:
// +----------------------------+
// | Type (1 octet) |
// +----------------------------+
// | Name length (1 octet) |
// +----------------------------+
// | Address length (1 octet) |
// +----------------------------+
// | Selector length (1 octet) |
// +----------------------------+
// | Data (variable) |
// +----------------------------+
type linkLayerAddr struct {
Type byte
Nlen byte
Alen byte
Slen byte
}
lla := (*linkLayerAddr)(unsafe.Pointer(&b[0]))
l := rsaAlignOf(int(4 + lla.Nlen + lla.Alen + lla.Slen))
if len(b) < l {
return nil, 0, EINVAL
}
b = b[4:]
sa := &SockaddrDatalink{Type: lla.Type, Nlen: lla.Nlen, Alen: lla.Alen, Slen: lla.Slen}
for i := 0; len(sa.Data) > i && i < int(lla.Nlen+lla.Alen+lla.Slen); i++ {
sa.Data[i] = int8(b[i])
}
return sa, l, nil
}
// parseSockaddrInet parses b as an internet socket address.
func parseSockaddrInet(b []byte, family byte) (Sockaddr, error) {
switch family {
case AF_INET:
if len(b) < SizeofSockaddrInet4 {
return nil, EINVAL
}
rsa := (*RawSockaddrAny)(unsafe.Pointer(&b[0]))
return anyToSockaddr(rsa)
case AF_INET6:
if len(b) < SizeofSockaddrInet6 {
return nil, EINVAL
}
rsa := (*RawSockaddrAny)(unsafe.Pointer(&b[0]))
return anyToSockaddr(rsa)
default:
return nil, EINVAL
}
}
const (
offsetofInet4 = int(unsafe.Offsetof(RawSockaddrInet4{}.Addr))
offsetofInet6 = int(unsafe.Offsetof(RawSockaddrInet6{}.Addr))
)
// parseNetworkLayerAddr parses b as an internet socket address in
// conventional BSD kernel form.
func parseNetworkLayerAddr(b []byte, family byte) (Sockaddr, error) {
// The encoding looks similar to the NLRI encoding.
// +----------------------------+
// | Length (1 octet) |
// +----------------------------+
// | Address prefix (variable) |
// +----------------------------+
//
// The differences between the kernel form and the NLRI
// encoding are:
//
// - The length field of the kernel form indicates the prefix
// length in bytes, not in bits
//
// - In the kernel form, zero value of the length field
// doesn't mean 0.0.0.0/0 or ::/0
//
// - The kernel form appends leading bytes to the prefix field
// to make the <length, prefix> tuple to be conformed with
// the routing messeage boundary
l := int(rsaAlignOf(int(b[0])))
if len(b) < l {
return nil, EINVAL
}
// Don't reorder case expressions.
// The case expressions for IPv6 must come first.
switch {
case b[0] == SizeofSockaddrInet6:
sa := &SockaddrInet6{}
copy(sa.Addr[:], b[offsetofInet6:])
return sa, nil
case family == AF_INET6:
sa := &SockaddrInet6{}
if l-1 < offsetofInet6 {
copy(sa.Addr[:], b[1:l])
} else {
copy(sa.Addr[:], b[l-offsetofInet6:l])
}
return sa, nil
case b[0] == SizeofSockaddrInet4:
sa := &SockaddrInet4{}
copy(sa.Addr[:], b[offsetofInet4:])
return sa, nil
default: // an old fashion, AF_UNSPEC or unknown means AF_INET
sa := &SockaddrInet4{}
if l-1 < offsetofInet4 {
copy(sa.Addr[:], b[1:l])
} else {
copy(sa.Addr[:], b[l-offsetofInet4:l])
}
return sa, nil
}
}
// 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, error)
}
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
}
func (m *RouteMessage) sockaddr() ([]Sockaddr, error) {
var sas [RTAX_MAX]Sockaddr
b := m.Data[:]
family := uint8(AF_UNSPEC)
for i := uint(0); i < RTAX_MAX && len(b) >= minRoutingSockaddrLen; i++ {
if m.Header.Addrs&(1<<i) == 0 {
continue
}
rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
switch rsa.Family {
case AF_LINK:
sa, err := parseSockaddrLink(b)
if err != nil {
return nil, err
}
sas[i] = sa
b = b[rsaAlignOf(int(rsa.Len)):]
case AF_INET, AF_INET6:
sa, err := parseSockaddrInet(b, rsa.Family)
if err != nil {
return nil, err
}
sas[i] = sa
b = b[rsaAlignOf(int(rsa.Len)):]
family = rsa.Family
default:
sa, err := parseNetworkLayerAddr(b, family)
if err != nil {
return nil, err
}
sas[i] = sa
b = b[rsaAlignOf(int(b[0])):]
}
}
return sas[:], nil
}
// InterfaceMessage represents a routing message containing
// network interface entries.
type InterfaceMessage struct {
Header IfMsghdr
Data []byte
}
func (m *InterfaceMessage) sockaddr() ([]Sockaddr, error) {
var sas [RTAX_MAX]Sockaddr
if m.Header.Addrs&RTA_IFP == 0 {
return nil, nil
}
sa, err := parseSockaddrLink(m.Data[:])
if err != nil {
return nil, err
}
sas[RTAX_IFP] = sa
return sas[:], nil
}
// InterfaceAddrMessage represents a routing message containing
// network interface address entries.
type InterfaceAddrMessage struct {
Header IfaMsghdr
Data []byte
}
func (m *InterfaceAddrMessage) sockaddr() ([]Sockaddr, error) {
var sas [RTAX_MAX]Sockaddr
b := m.Data[:]
family := uint8(AF_UNSPEC)
for i := uint(0); i < RTAX_MAX && len(b) >= minRoutingSockaddrLen; i++ {
if m.Header.Addrs&(1<<i) == 0 {
continue
}
rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))
switch rsa.Family {
case AF_LINK:
sa, err := parseSockaddrLink(b)
if err != nil {
return nil, err
}
sas[i] = sa
b = b[rsaAlignOf(int(rsa.Len)):]
case AF_INET, AF_INET6:
sa, err := parseSockaddrInet(b, rsa.Family)
if err != nil {
return nil, err
}
sas[i] = sa
b = b[rsaAlignOf(int(rsa.Len)):]
family = rsa.Family
default:
sa, err := parseNetworkLayerAddr(b, family)
if err != nil {
return nil, err
}
sas[i] = sa
b = b[rsaAlignOf(int(b[0])):]
}
}
return sas[:], nil
}
// ParseRoutingMessage parses b as routing messages and returns the
// slice containing the RoutingMessage interfaces.
func ParseRoutingMessage(b []byte) (msgs []RoutingMessage, err error) {
nmsgs, nskips := 0, 0
for len(b) >= anyMessageLen {
nmsgs++
any := (*anyMessage)(unsafe.Pointer(&b[0]))
if any.Version != RTM_VERSION {
b = b[any.Msglen:]
continue
}
if m := any.toRoutingMessage(b); m == nil {
nskips++
} else {
msgs = append(msgs, m)
}
b = b[any.Msglen:]
}
// We failed to parse any of the messages - version mismatch?
if nmsgs != len(msgs)+nskips {
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) ([]Sockaddr, error) {
sas, err := msg.sockaddr()
if err != nil {
return nil, err
}
return sas, nil
}