你可以使用什么系统调用/方法来获取默认的网络网关。

huangapple
go评论116阅读模式
英文:

what syscall/method could I use to get the default network gateway

问题

使用Go语言，可以使用哪个包、本地函数或系统调用来获取*nix系统上的默认网关？

我想避免创建一个包装器来调用netstat、route、ip等命令，或者读取、解析现有文件，我的想法是以最兼容不同操作系统/平台的方式获取这些值。

例如，这是route命令的输出：

  1. $ route -n get default
  2.    route to: default
  3. destination: default
  4.        mask: default
  5.     gateway: 192.168.1.1
  6.   interface: en1
  7.       flags: <UP,GATEWAY,DONE,STATIC,PRCLONING>
  8.  recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
  9.        0         0         0         0         0         0      1500         0

我想做类似的事情，只是打印/获取网关地址和接口。

英文:

Using Go what package, native function, syscall could be used to obtain the default gateway on a *nix system

I would like to avoid creating a wrapper arround netstat, route, ip, etc commands, or read, parse an existing file, the idea is to obtain the values the most os/platform agnostic way posible.

For example this is the output of the route command:

  1. $ route -n get default
  2.    route to: default
  3. destination: default
  4.        mask: default
  5.     gateway: 192.168.1.1
  6.   interface: en1
  7.       flags: &lt;UP,GATEWAY,DONE,STATIC,PRCLONING&gt;
  8.  recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
  9.        0         0         0         0         0         0      1500         0

I would like to do something simliar in order to just print/obtain the gateeway address/interface.

答案1

得分: 4

对于Linux系统，你可以使用procfs，如captncraig所建议的。以下是一个代码片段，提取网关地址并将其转换为点分十进制的IPv4地址。

  1. /* /proc/net/route文件内容：
  2. Iface	Destination	Gateway 	Flags	RefCnt	Use	Metric	Mask
  3. eno1	00000000	C900A8C0	0003	0	0	100	00000000	0	00                                                                              eno1	0000A8C0	00000000	0001	0	0	100	00FFFFFF	0	00 
  4. */
  6. const (
  7. 	file  = "/proc/net/route"
  8. 	line  = 1    // 包含网关地址的行号（第一行为0）
  9. 	sep   = "\t" // 字段分隔符
  10. 	field = 2    // 包含十六进制网关地址的字段号（第一个字段为0）
  11. )
  13. func main() {
  15. 	file, err := os.Open(file)
  16. 	if err != nil {
  17. 		log.Fatal(err)
  18. 	}
  19. 	defer file.Close()
  21. 	scanner := bufio.NewScanner(file)
  22. 	for scanner.Scan() {
  24. 		// 跳转到包含网关地址的行
  25. 		for i := 0; i < line; i++ {
  26. 			scanner.Scan()
  27. 		}
  29. 		// 获取包含网关地址的字段
  30. 		tokens := strings.Split(scanner.Text(), sep)
  31. 		gatewayHex := "0x" + tokens[field]
  33. 		// 将十六进制地址转换为uint32
  34. 		d, _ := strconv.ParseInt(gatewayHex, 0, 64)
  35. 		d32 := uint32(d)
  37. 		// 从uint32创建net.IP地址
  38. 		ipd32 := make(net.IP, 4)
  39. 		binary.LittleEndian.PutUint32(ipd32, d32)
  40. 		fmt.Printf("%T --> %[1]v\n", ipd32)
  42. 		// 将net.IP格式化为点分十进制的IPv4字符串
  43. 		ip := net.IP(ipd32).String()
  44. 		fmt.Printf("%T --> %[1]v\n", ip)
  46. 		// 退出扫描器
  47. 		break
  48. 	}
  49. }
英文:

For Linux, you can use the procfs as suggested by captncraig. Here is a snippet that extracts the gateway address and convert it to quad dotted ipV4.

  1. /* /proc/net/route file:
  2. Iface	Destination	Gateway 	Flags	RefCnt	Use	Metric	Mask
  3. eno1	00000000	C900A8C0	0003	0	0	100	00000000	0	00                                                                             
  4. eno1	0000A8C0	00000000	0001	0	0	100	00FFFFFF	0	00 
  5. */
  7. const (
  8. 	file  = &quot;/proc/net/route&quot;
  9. 	line  = 1    // line containing the gateway addr. (first line: 0)
  10. 	sep   = &quot;\t&quot; // field separator
  11. 	field = 2    // field containing hex gateway address (first field: 0)
  12. )
  14. func main() {
  16. 	file, err := os.Open(file)
  17. 	if err != nil {
  18. 		log.Fatal(err)
  19. 	}
  20. 	defer file.Close()
  22. 	scanner := bufio.NewScanner(file)
  23. 	for scanner.Scan() {
  25. 		// jump to line containing the agteway address
  26. 		for i := 0; i &lt; line; i++ {
  27. 			scanner.Scan()
  28. 		}
  30. 		// get field containing gateway address
  31. 		tokens := strings.Split(scanner.Text(), sep)
  32. 		gatewayHex := &quot;0x&quot; + tokens[field]
  34. 		// cast hex address to uint32
  35. 		d, _ := strconv.ParseInt(gatewayHex, 0, 64)
  36. 		d32 := uint32(d)
  38. 		// make net.IP address from uint32
  39. 		ipd32 := make(net.IP, 4)
  40. 		binary.LittleEndian.PutUint32(ipd32, d32)
  41. 		fmt.Printf(&quot;%T --&gt; %[1]v\n&quot;, ipd32)
  43. 		// format net.IP to dotted ipV4 string
  44. 		ip := net.IP(ipd32).String()
  45. 		fmt.Printf(&quot;%T --&gt; %[1]v\n&quot;, ip)
  47. 		// exit scanner
  48. 		break
  49. 	}
  50. }

答案2

得分: 2

一种选择是读取/proc/net/route文件。在我的某个系统上，该文件包含以下内容：

  1. 接口	目标	网关	标志	引用计数	使用	度量	掩码	MTU	窗口	IRTT                                                       
  2. team0	00000000	010017BA	0003	0	0	0	00000000	0	0	0                                                                              
  3. team0	0000070A	00000000	0001	0	0	0	00FEFFFF	0	0	0

你可以读取该文件，使用一些文本处理技术捕获网关，并将十六进制字符串转换为net.IP类型。这有点绕弯，但我找不到任何可以在标准库或其他地方为您访问此内容的包。

英文:

One option would be to read /proc/net/route. On one of my systems this contains:

  1. Iface	Destination	Gateway 	Flags	RefCnt	Use	Metric	Mask		MTU	Window	IRTT                                                       
  2. team0	00000000	010017BA 	0003	0	0	0	00000000	0	0	0                                                                              
  3. team0	0000070A	00000000	0001	0	0	0	00FEFFFF	0	0	0

You could read that in, capture the gateway with some text processing, and convert the hex string to a net.IP. Kinda a runaround, but I could not find any package that can access this for you in the std lib or elsewhere.

答案3

得分: 0

这里有一个名为 github.com/jackpal/gateway 的库。它支持多个平台，并且具有非常直观的接口：

  1. package main
  3. import (
  4. 	"fmt"
  6. 	"github.com/jackpal/gateway"
  7. )
  9. func main() {
  10. 	gatewayIP, err := gateway.DiscoverGateway()
  11. 	if err != nil {
  12. 		panic(err)
  13. 	}
  14. 	fmt.Println("网关 IP：", gatewayIP)
  15. }

它还有一个 DiscoverInterface 函数，可以获取通过默认网关访问的接口的 IP 地址。

英文:

There's github.com/jackpal/gateway. It supports multiple platforms and has a very straightforward interface:

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  6. 	&quot;github.com/jackpal/gateway&quot;
  7. )
  9. func main() {
  10. 	gatewayIP, err := gateway.DiscoverGateway()
  11. 	if err != nil {
  12. 		panic(err)
  13. 	}
  14. 	fmt.Println(&quot;Gateway IP:&quot;, gatewayIP)
  15. }

It also has a DiscoverInterface function which can obtain the IP address of the interface through which the default gateway is reached.

答案4

得分: -4

在https://github.com/golang/net/blob/master/internal/nettest/interface.go上玩RoutedInterface()代码。

示例代码片段：

  1. rifs := nettest.RoutedInterface("ip", net.FlagUp | net.FlagBroadcast)
  2. if rifs != nil {
  3.     fmt.Println("Routed interface is ",rifs.HardwareAddr.String())
  4.     fmt.Println("Flags are", rifs.Flags.String())
  5. }

注意：由于不允许直接调用/internal，您需要将golang代码复制到本地库中。

英文:

Play with the RoutedInterface() code at https://github.com/golang/net/blob/master/internal/nettest/interface.go

Sample code snip:

  1. rifs := nettest.RoutedInterface(&quot;ip&quot;, net.FlagUp | net.FlagBroadcast)
  2. if rifs != nil {
  3.     fmt.Println(&quot;Routed interface is &quot;,rifs.HardwareAddr.String())
  4.     fmt.Println(&quot;Flags are&quot;, rifs.Flags.String())
  5. }

Note: You will need to copy the golang code into a local library, since /internal calls are not allowed directly.

huangapple
  • 本文由 发表于 2016年11月19日 01:23:14
  • 转载请务必保留本文链接：https://go.coder-hub.com/40682760.html
  • go
  • networking
  • system-calls
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