我有以下代码,它应该使用RTNETLINK套接字监视网络更改。但是当我为接口设置新的IP地址" New Addr"或者" Del Addr"不显示。可能出现什么问题。
package main
import (
"fmt"
"syscall"
)
func main() {
l, _ := ListenNetlink()
for {
msgs, err := l.ReadMsgs()
if err != nil {
fmt.Println("Could not read netlink: %s", err)
}
for _, m := range msgs {
if IsNewAddr(&m) {
fmt.Println("New Addr")
}
if IsDelAddr(&m) {
fmt.Println("Del Addr")
}
}
}
}
type NetlinkListener struct {
fd int
sa *syscall.SockaddrNetlink
}
func ListenNetlink() (*NetlinkListener, error) {
groups := syscall.RTNLGRP_LINK |
syscall.RTNLGRP_IPV4_IFADDR |
syscall.RTNLGRP_IPV6_IFADDR
s, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_DGRAM,
syscall.NETLINK_ROUTE)
if err != nil {
return nil, fmt.Errorf("socket: %s", err)
}
saddr := &syscall.SockaddrNetlink{
Family: syscall.AF_NETLINK,
Pid: uint32(0),
Groups: uint32(groups),
}
err = syscall.Bind(s, saddr)
if err != nil {
return nil, fmt.Errorf("bind: %s", err)
}
return &NetlinkListener{fd: s, sa: saddr}, nil
}
func (l *NetlinkListener) ReadMsgs() ([]syscall.NetlinkMessage, error) {
defer func() {
recover()
}()
pkt := make([]byte, 2048)
n, err := syscall.Read(l.fd, pkt)
if err != nil {
return nil, fmt.Errorf("read: %s", err)
}
msgs, err := syscall.ParseNetlinkMessage(pkt[:n])
if err != nil {
return nil, fmt.Errorf("parse: %s", err)
}
return msgs, nil
}
func IsNewAddr(msg *syscall.NetlinkMessage) bool {
if msg.Header.Type == syscall.RTM_NEWADDR {
return true
}
return false
}
func IsDelAddr(msg *syscall.NetlinkMessage) bool {
if msg.Header.Type == syscall.RTM_DELADDR {
return true
}
return false
}
func IsRelevant(msg *syscall.IfAddrmsg) bool {
if msg.Scope == syscall.RT_SCOPE_UNIVERSE ||
msg.Scope == syscall.RT_SCOPE_SITE {
return true
}
return false
}
答案 0 :(得分:2)
我在 syscall.go
文件中找到了包。常量变量syscall.RTNLGRP_IPV4_IFADDR=0x5
。但是,在rtnetlink.h
source中定义的C语言中的模拟RTMGRP_IPV4_IFADDR
常量具有以下不同的值:
#define RTMGRP_IPV4_IFADDR 0x10
我通过github.com提交了issue,我希望它会在即将发布的版本中修复。
现在,您可以在 0x10
的代码中使用0x5
。它会完美运作。
原来它根本不是bug。他们没有从rtnetlink.h
source重新声明RTMGRP_*
常量变量组,并且由于syscall.go
被冻结,因此不希望在功能中添加此变量。但是,他们建议使用RTNLGRP_*
,RTMGRP_*
也在rtnetlink.h
source中声明。然而,这两组常数变量在以下方式上是不同的。 RTMGRP_IPV4_IFADDR = 0x10
组表示位值(即:RTLNGRP_*
)并为用户空间后向功能声明。 RTNLGRP_IPV4_IFADDR=0x5
组表示位位置而不是位值(即:1 << (RTNLGRP_* - 1)
),可以通过以下方式转换为位值M1 *
答案 1 :(得分:2)
根据接受的答案,修复它以将groups
更改为以下内容:
groups := (1 << (syscall.RTNLGRP_LINK - 1)) |
(1 << (syscall.RTNLGRP_IPV4_IFADDR - 1)) |
(1 << (syscall.RTNLGRP_IPV6_IFADDR - 1))
答案 2 :(得分:0)
这是* BSD的等效代码:
package main
import (
"fmt"
"log"
"syscall"
)
func main() {
netlink, err := ListenNetlink()
if err != nil {
log.Printf("[ERR] Could not create netlink listener: %v", err)
return
}
for {
msgs, err := netlink.ReadMsgs()
if err != nil {
log.Printf("[ERR] Could not read netlink: %v", err)
}
for _, msg := range msgs {
if _, ok := msg.(*syscall.InterfaceAddrMessage); ok {
log.Printf("address change!")
}
}
}
}
type NetlinkListener struct {
fd int
}
func ListenNetlink() (*NetlinkListener, error) {
s, err := syscall.Socket(syscall.AF_ROUTE, syscall.SOCK_RAW, syscall.AF_UNSPEC)
if err != nil {
return nil, fmt.Errorf("socket: %s", err)
}
return &NetlinkListener{fd: s}, nil
}
func (l *NetlinkListener) ReadMsgs() ([]syscall.RoutingMessage, error) {
defer func() {
recover()
}()
pkt := make([]byte, 2048)
n, err := syscall.Read(l.fd, pkt)
if err != nil {
return nil, fmt.Errorf("read: %s", err)
}
msgs, err := syscall.ParseRoutingMessage(pkt[:n])
if err != nil {
return nil, fmt.Errorf("parse: %s", err)
}
return msgs, nil
}
答案 3 :(得分:0)
更新示例应为
package main
import (
"fmt"
"syscall"
)
func main() {
l, _ := ListenNetlink()
for {
msgs, err := l.ReadMsgs()
if err != nil {
fmt.Println("Could not read netlink: %s", err)
}
for _, m := range msgs {
if IsNewAddr(&m) {
fmt.Println("New Addr")
}
if IsDelAddr(&m) {
fmt.Println("Del Addr")
}
}
}
}
type NetlinkListener struct {
fd int
sa *syscall.SockaddrNetlink
}
func ListenNetlink() (*NetlinkListener, error) {
groups := (1 << (syscall.RTNLGRP_LINK - 1)) |
(1 << (syscall.RTNLGRP_IPV4_IFADDR - 1)) |
(1 << (syscall.RTNLGRP_IPV6_IFADDR - 1))
s, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_DGRAM,
syscall.NETLINK_ROUTE)
if err != nil {
return nil, fmt.Errorf("socket: %s", err)
}
saddr := &syscall.SockaddrNetlink{
Family: syscall.AF_NETLINK,
Pid: uint32(0),
Groups: uint32(groups),
}
err = syscall.Bind(s, saddr)
if err != nil {
return nil, fmt.Errorf("bind: %s", err)
}
return &NetlinkListener{fd: s, sa: saddr}, nil
}
func (l *NetlinkListener) ReadMsgs() ([]syscall.NetlinkMessage, error) {
defer func() {
recover()
}()
pkt := make([]byte, 2048)
n, err := syscall.Read(l.fd, pkt)
if err != nil {
return nil, fmt.Errorf("read: %s", err)
}
msgs, err := syscall.ParseNetlinkMessage(pkt[:n])
if err != nil {
return nil, fmt.Errorf("parse: %s", err)
}
return msgs, nil
}
func IsNewAddr(msg *syscall.NetlinkMessage) bool {
if msg.Header.Type == syscall.RTM_NEWADDR {
return true
}
return false
}
func IsDelAddr(msg *syscall.NetlinkMessage) bool {
if msg.Header.Type == syscall.RTM_DELADDR {
return true
}
return false
}
// rtm_scope is the distance to the destination:
//
// RT_SCOPE_UNIVERSE global route
// RT_SCOPE_SITE interior route in the
// local autonomous system
// RT_SCOPE_LINK route on this link
// RT_SCOPE_HOST route on the local host
// RT_SCOPE_NOWHERE destination doesn't exist
//
// The values between RT_SCOPE_UNIVERSE and RT_SCOPE_SITE are
// available to the user.
func IsRelevant(msg *syscall.IfAddrmsg) bool {
if msg.Scope == syscall.RT_SCOPE_UNIVERSE ||
msg.Scope == syscall.RT_SCOPE_SITE {
return true
}
return false
}