golang route 代码
文件路径：/src/vendor/golang.org/x/net/route/route.go
/ Copyright 2016 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.
/go:build darwin || dragonfly || freebsd || netbsd || openbsd
/ +build darwin dragonfly freebsd netbsd openbsd
/ Package route provides basic functions for the manipulation of
/ packet routing facilities on BSD variants.
/
/ The package supports any version of Darwin, any version of
/ DragonFly BSD, FreeBSD 7 and above, NetBSD 6 and above, and OpenBSD
/ 5.6 and above.
package route
import (
"errors"
"os"
"syscall"
)
var (
errUnsupportedMessage = errors.New("unsupported message")
errMessageMismatch = errors.New("message mismatch")
errMessageTooShort = errors.New("message too short")
errInvalidMessage = errors.New("invalid message")
errInvalidAddr = errors.New("invalid address")
errShortBuffer = errors.New("short buffer")
)
/ A RouteMessage represents a message conveying an address prefix, a
/ nexthop address and an output interface.
/
/ Unlike other messages, this message can be used to query adjacency
/ information for the given address prefix, to add a new route, and
/ to delete or modify the existing route from the routing information
/ base inside the kernel by writing and reading route messages on a
/ routing socket.
/
/ For the manipulation of routing information, the route message must
/ contain appropriate fields that include:
/
/ Version = <must be specified>
/ Type = <must be specified>
/ Flags = <must be specified>
/ Index = <must be specified if necessary>
/ ID = <must be specified>
/ Seq = <must be specified>
/ Addrs = <must be specified>
/
/ The Type field specifies a type of manipulation, the Flags field
/ specifies a class of target information and the Addrs field
/ specifies target information like the following:
/
/ route.RouteMessage{
/ Version: RTM_VERSION,
/ Type: RTM_GET,
/ Flags: RTF_UP | RTF_HOST,
/ ID: uintptr(os.Getpid()),
/ Seq: 1,
/ Addrs: []route.Addrs{
/ RTAX_DST: &route.Inet4Addr{ ... },
/ RTAX_IFP: &route.LinkAddr{ ... },
/ RTAX_BRD: &route.Inet4Addr{ ... },
/ },
/ }
/
/ The values for the above fields depend on the implementation of
/ each operating system.
/
/ The Err field on a response message contains an error value on the
/ requested operation. If non-nil, the requested operation is failed.
type RouteMessage struct {
Version int / message version
Type int / message type
Flags int / route flags
Index int / interface index when attached
ID uintptr / sender's identifier; usually process ID
Seq int / sequence number
Err error / error on requested operation
Addrs []Addr / addresses
extOff int / offset of header extension
raw []byte / raw message
}
/ Marshal returns the binary encoding of m.
func (m *RouteMessage) Marshal() ([]byte, error) {
return m.marshal()
}
/ A RIBType represents a type of routing information base.
type RIBType int
const (
RIBTypeRoute RIBType = syscall.NET_RT_DUMP
RIBTypeInterface RIBType = syscall.NET_RT_IFLIST
)
/ FetchRIB fetches a routing information base from the operating
/ system.
/
/ The provided af must be an address family.
/
/ The provided arg must be a RIBType-specific argument.
/ When RIBType is related to routes, arg might be a set of route
/ flags. When RIBType is related to network interfaces, arg might be
/ an interface index or a set of interface flags. In most cases, zero
/ means a wildcard.
func FetchRIB(af int, typ RIBType, arg int) ([]byte, error) {
try := 0
for {
try++
mib := [6]int32{sysCTL_NET, sysAF_ROUTE, 0, int32(af), int32(typ), int32(arg)}
n := uintptr(0)
if err := sysctl(mib[:], nil, &n, nil, 0); err != nil {
return nil, os.NewSyscallError("sysctl", err)
}
if n == 0 {
return nil, nil
}
b := make([]byte, n)
if err := sysctl(mib[:], &b[0], &n, nil, 0); err != nil {
/ If the sysctl failed because the data got larger
/ between the two sysctl calls, try a few times
/ before failing. (golang.org/issue/45736).
const maxTries = 3
if err == syscall.ENOMEM && try < maxTries {
continue
}
return nil, os.NewSyscallError("sysctl", err)
}
return b[:n], nil
}
}