在MacOS上使用”arp -a”工具时，出现了奇怪的MAC地址格式。

huangapple
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英文:

Weird MAC address format using "arp -a" tool on MacOS

问题

我想在MacOS上使用Go语言中的net.ParseMAC函数解析arp -a命令的输出，但由于奇怪的格式，我遇到了错误。

arp -a命令的示例输出如下：

  1. > arp -a 
  2. ? (192.168.1.1) at 0:22:7:4a:21:d5 on en0 ifscope [ethernet]
  3. ? (224.0.0.251) at 1:0:5e:0:0:fb on en0 ifscope permanent [ethernet]
  4. ? (239.255.255.250) at 1:0:5e:7f:ff:fa on en0 ifscope permanent [ethernet]

MAC地址的格式不符合预期，因为MAC地址中的01和00被简化为只有1和0。似乎允许的格式是A:B:C:D:E:F，而不是AA:BB:CC:DD:EE:FF。

我该如何将输出转换为后一种格式，以便可以被net.ParseMAC函数接受？

编辑：
我编写了一个简单的Go函数来解决省略前导零的问题：

  1. // FixMacOSMACNotation 修复 macOS 上的 MAC 地址表示法。
  2. // 例如：1:0:5e:7f:ff:fa 变为 01:00:5e:7f:ff:fa
  3. func FixMacOSMACNotation(s string) string {
  4.     var newString string
  5.     split := strings.Split(s, ":")
  6.     for i, s := range split {
  7.         if i != 0 {
  8.             newString += ":"
  9.         }
  10.         if len(s) == 1 {
  11.             newString += "0" + s
  12.         } else {
  13.             newString += s
  14.         }
  15.     }
  16.     return newString
  17. }

然后可以在net.ParseMAC中成功使用它。

英文:

I want to parse output from the arp -a command on MacOS, in Go using the net.ParseMAC function, however I'm getting an error due to the weird formatting.
Sample output from arp -a command:

  1. > arp -a 
  2. ? (192.168.1.1) at 0:22:7:4a:21:d5 on en0 ifscope [ethernet]
  3. ? (224.0.0.251) at 1:0:5e:0:0:fb on en0 ifscope permanent [ethernet]
  4. ? (239.255.255.250) at 1:0:5e:7f:ff:fa on en0 ifscope permanent [ethernet]

The MAC formatting is unexpected because instead of doing 01 and 00, the MAC addresses include just 1 and 0. It seems the formatting is allowed to be A:B:C:D:E:F instead of AA:BB:CC:DD:EE:FF.

How can I make the output in the latter format, so it can be accepted by the net.ParseMAC function?

Edit:
I made a simple Go function to solve the leaving off leading zeroes problem:

  1. // FixMacOSMACNotation fixes the notation of MAC address on macOS.
  2. // For instance: 1:0:5e:7f:ff:fa becomes 01:00:5e:7f:ff:fa
  3. func FixMacOSMACNotation(s string) string {
  4. 	var newString string
  5. 	split := strings.Split(s, ":")
  6. 	for i, s := range split {
  7. 		if i != 0 {
  8. 			newString += ":"
  9. 		}
  10. 		if len(s) == 1 {
  11. 			newString += "0" + s
  12. 		} else {
  13. 			newString += s
  14. 		}
  15. 	}
  16. 	return newString
  17. }

Which can then be used in net.ParseMAC successfully.

答案1

得分: 1

这个版本使用strings.Builder来修复OP所需的输入。

使用[strings.]Builder可以高效地构建字符串，使用Write方法。它最小化了内存复制。零值是可以直接使用的。不要复制非零的Builder。

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"strings"
  6. )
  8. func main() {
  9. 	inputs := []string{
  10. 		"1:0:5e:7f:ff:fa",
  11. 		"1:0:5e:7f:ff:f",
  12. 		"1:0:5e:7f:ff:",
  13. 		"1:0:5e::ff:",
  14. 	}
  16. 	for _, input := range inputs {
  17. 		fmt.Println()
  18. 		fmt.Println("FixMacOSMACNotation    ", FixMacOSMACNotation(input))
  19. 	}
  20. }
  22. // FixMacOSMACNotation修复了macOS上MAC地址的表示方式。
  23. // 例如：1:0:5e:7f:ff:fa变为01:00:5e:7f:ff:fa
  24. func FixMacOSMACNotation(s string) string {
  25. 	var e int
  26. 	var sb strings.Builder
  27. 	for i := 0; i < len(s); i++ {
  28. 		r := s[i]
  29. 		if r == ':' {
  30. 			for j := e; j < 2; j++ {
  31. 				sb.WriteString("0")
  32. 			}
  33. 			sb.WriteString(s[i-e : i])
  34. 			sb.WriteString(":")
  35. 			e = 0
  36. 			continue
  37. 		}
  38. 		e++
  39. 	}
  40. 	for j := e; j < 2; j++ {
  41. 		sb.WriteString("0")
  42. 	}
  43. 	sb.WriteString(s[len(s)-e:])
  44. 	return sb.String()
  45. }

在这里尝试一下。

英文:

This version uses strings.Builder to fix the given input as desired by OP.

A [strings.]Builder is used to efficiently build a string using Write methods. It minimizes memory copying. The zero value is ready to use. Do not copy a non-zero Builder.

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;strings&quot;
  6. )
  8. func main() {
  9. 	inputs := []string{
  10. 		&quot;1:0:5e:7f:ff:fa&quot;,
  11. 		&quot;1:0:5e:7f:ff:f&quot;,
  12. 		&quot;1:0:5e:7f:ff:&quot;,
  13. 		&quot;1:0:5e::ff:&quot;,
  14. 	}
  16. 	for _, input := range inputs {
  17. 		fmt.Println()
  18. 		fmt.Println(&quot;FixMacOSMACNotation    &quot;, FixMacOSMACNotation(input))
  19. 	}
  20. }
  22. // FixMacOSMACNotation fixes the notation of MAC address on macOS.
  23. // For instance: 1:0:5e:7f:ff:fa becomes 01:00:5e:7f:ff:fa
  24. func FixMacOSMACNotation(s string) string {
  25. 	var e int
  26. 	var sb strings.Builder
  27. 	for i := 0; i &lt; len(s); i++ {
  28. 		r := s[i]
  29. 		if r == &#39;:&#39; {
  30. 			for j := e; j &lt; 2; j++ {
  31. 				sb.WriteString(&quot;0&quot;)
  32. 			}
  33. 			sb.WriteString(s[i-e : i])
  34. 			sb.WriteString(&quot;:&quot;)
  35. 			e = 0
  36. 			continue
  37. 		}
  38. 		e++
  39. 	}
  40. 	for j := e; j &lt; 2; j++ {
  41. 		sb.WriteString(&quot;0&quot;)
  42. 	}
  43. 	sb.WriteString(s[len(s)-e:])
  44. 	return sb.String()
  45. }

try it here

huangapple
  • 本文由 发表于 2021年9月14日 02:21:33
  • 转载请务必保留本文链接：https://go.coder-hub.com/69167416.html
  • bsd
  • go
  • linux
  • macos
  • network-programming
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