123 lines
3.9 KiB
Go
123 lines
3.9 KiB
Go
// Copyright 2016 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 dragonfly freebsd netbsd openbsd
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// Package route provides basic functions for the manipulation of
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// packet routing facilities on BSD variants.
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//
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// The package supports any version of Darwin, any version of
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// DragonFly BSD, FreeBSD 7 through 11, NetBSD 6 and above, and
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// OpenBSD 5.6 and above.
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package route
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import (
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"errors"
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"os"
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"syscall"
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)
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var (
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errUnsupportedMessage = errors.New("unsupported message")
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errMessageMismatch = errors.New("message mismatch")
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errMessageTooShort = errors.New("message too short")
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errInvalidMessage = errors.New("invalid message")
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errInvalidAddr = errors.New("invalid address")
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errShortBuffer = errors.New("short buffer")
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)
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// A RouteMessage represents a message conveying an address prefix, a
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// nexthop address and an output interface.
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//
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// Unlike other messages, this message can be used to query adjacency
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// information for the given address prefix, to add a new route, and
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// to delete or modify the existing route from the routing information
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// base inside the kernel by writing and reading route messages on a
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// routing socket.
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//
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// For the manipulation of routing information, the route message must
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// contain appropriate fields that include:
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//
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// Version = <must be specified>
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// Type = <must be specified>
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// Flags = <must be specified>
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// Index = <must be specified if necessary>
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// ID = <must be specified>
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// Seq = <must be specified>
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// Addrs = <must be specified>
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//
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// The Type field specifies a type of manipulation, the Flags field
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// specifies a class of target information and the Addrs field
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// specifies target information like the following:
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//
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// route.RouteMessage{
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// Version: RTM_VERSION,
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// Type: RTM_GET,
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// Flags: RTF_UP | RTF_HOST,
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// ID: uintptr(os.Getpid()),
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// Seq: 1,
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// Addrs: []route.Addrs{
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// RTAX_DST: &route.Inet4Addr{ ... },
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// RTAX_IFP: &route.LinkAddr{ ... },
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// RTAX_BRD: &route.Inet4Addr{ ... },
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// },
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// }
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//
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// The values for the above fields depend on the implementation of
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// each operating system.
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//
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// The Err field on a response message contains an error value on the
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// requested operation. If non-nil, the requested operation is failed.
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type RouteMessage struct {
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Version int // message version
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Type int // message type
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Flags int // route flags
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Index int // interface index when atatched
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ID uintptr // sender's identifier; usually process ID
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Seq int // sequence number
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Err error // error on requested operation
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Addrs []Addr // addresses
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extOff int // offset of header extension
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raw []byte // raw message
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}
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// Marshal returns the binary encoding of m.
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func (m *RouteMessage) Marshal() ([]byte, error) {
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return m.marshal()
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}
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// A RIBType reprensents a type of routing information base.
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type RIBType int
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const (
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RIBTypeRoute RIBType = syscall.NET_RT_DUMP
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RIBTypeInterface RIBType = syscall.NET_RT_IFLIST
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)
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// FetchRIB fetches a routing information base from the operating
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// system.
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//
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// The provided af must be an address family.
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//
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// The provided arg must be a RIBType-specific argument.
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// When RIBType is related to routes, arg might be a set of route
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// flags. When RIBType is related to network interfaces, arg might be
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// an interface index or a set of interface flags. In most cases, zero
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// means a wildcard.
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func FetchRIB(af int, typ RIBType, arg int) ([]byte, error) {
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mib := [6]int32{sysCTL_NET, sysAF_ROUTE, 0, int32(af), int32(typ), int32(arg)}
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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, os.NewSyscallError("sysctl", 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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b := make([]byte, n)
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if err := sysctl(mib[:], &b[0], &n, nil, 0); err != nil {
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return nil, os.NewSyscallError("sysctl", err)
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}
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return b[:n], nil
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}
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