src/syscall/route_bsd.go - go - Git at Google

 // 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 follwoing:
 	// +----------------------------+
 	// | 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
 }
	// 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 follwoing:
	// +----------------------------+
	// \| 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
	}