检测不同类型网络错误的便携方法

huangapple
go评论121阅读模式
英文:

Portable way to detect different kinds of network error

问题

我想要确定网络层发生了什么样的错误。我找到的唯一方法是使用正则表达式检查错误消息，但现在我发现这些消息可能是不同的语言（取决于操作系统配置），这使得通过正则表达式难以检测。有没有更好的方法来做到这一点？

  1. package main
  3. import (
  4.   "github.com/miekg/dns"
  5.   "net"
  6.   "regexp"
  7. )
  9. func main() {
  10.   var c dns.Client
  11.   m := new(dns.Msg)
  13.   m.SetQuestion("3com.br.", dns.TypeSOA)
  14.   _, _, err := c.Exchange(m, "ns1.3com.com.:53")
  15.   checkErr(err)
  17.   m.SetQuestion("example.com.", dns.TypeSOA)
  18.   _, _, err = c.Exchange(m, "idontexist.br.:53")
  19.   checkErr(err)
  21.   m.SetQuestion("acasadocartaocuritiba.blog.br.", dns.TypeSOA)
  22.   _, _, err = c.Exchange(m, "ns7.storedns22.in.:53")
  23.   checkErr(err)
  24. }
  26. func checkErr(err error) {
  27.   if err == nil {
  28.     println("Ok")
  29.   } else if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
  30.     println("Timeout")
  31.   } else if match, _ := regexp.MatchString(".*lookup.*", err.Error()); match {
  32.     println("Unknown host")
  33.   } else if match, _ := regexp.MatchString(".*connection refused.*", err.Error()); match {
  34.     println("Connection refused")
  35.   } else {
  36.     println("Other error")
  37.   }
  38. }

结果：

  1. $ go run neterrors.go
  2. Timeout
  3. Unknown host
  4. Connection refused

我在使用葡萄牙语作为默认语言的 Windows 操作系统中测试系统时发现了这个问题。

[编辑]

我找到了一种使用 OpError 的方法。这是带有新方法的 checkErr 函数。如果有人有更好的解决方案，我将非常乐意了解！

  1. func checkErr(err error) {
  2.   if err == nil {
  3.     println("Ok")
  4.   } else if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
  5.     println("Timeout")
  6.   } else if opError, ok := err.(*net.OpError); ok {
  7.     if opError.Op == "dial" {
  8.       println("Unknown host")
  9.     } else if opError.Op == "read" {
  10.       println("Connection refused")
  11.     }
  12.   }
  13. }

[编辑2]

根据 seong 的回答进行了更新。

  1. func checkErr(err error) {
  2.   if err == nil {
  3.     println("Ok")
  4.     return
  5.   } else if netError, ok := err.(net.Error); ok && netError.Timeout() {
  6.     println("Timeout")
  7.     return
  8.   }
  10.   switch t := err.(type) {
  11.   case *net.OpError:
  12.     if t.Op == "dial" {
  13.       println("Unknown host")
  14.     } else if t.Op == "read" {
  15.       println("Connection refused")
  16.     }
  17.   case syscall.Errno:
  18.     if t == syscall.ECONNREFUSED {
  19.       println("Connection refused")
  20.     }
  21.   }
  22. }
英文:

I would like to identify what kind of error occurred in the network level. The only way I found was checking the error messages with a regular expression, but now I discovered that this messages can be in different languages (depending on the OS configuration), making it difficult to detect by regular expressions. Is there a better way to do it?

  1. package main
  3. import (
  4.   "github.com/miekg/dns"
  5.   "net"
  6.   "regexp"
  7. )
  9. func main() {
  10.   var c dns.Client
  11.   m := new(dns.Msg)
  13.   m.SetQuestion("3com.br.", dns.TypeSOA)
  14.   _, _, err := c.Exchange(m, "ns1.3com.com.:53")
  15.   checkErr(err)
  17.   m.SetQuestion("example.com.", dns.TypeSOA)
  18.   _, _, err = c.Exchange(m, "idontexist.br.:53")
  19.   checkErr(err)
  21.   m.SetQuestion("acasadocartaocuritiba.blog.br.", dns.TypeSOA)
  22.   _, _, err = c.Exchange(m, "ns7.storedns22.in.:53")
  23.   checkErr(err)
  24. }
  26. func checkErr(err error) {
  27.   if err == nil {
  28.     println("Ok")
  29.   } else if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
  30.     println("Timeout")
  31.   } else if match, _ := regexp.MatchString(".*lookup.*", err.Error()); match {
  32.     println("Unknown host")
  33.   } else if match, _ := regexp.MatchString(".*connection refused.*", err.Error()); match {
  34.     println("Connection refused")
  35.   } else {
  36.     println("Other error")
  37.   }
  38. }

Result:

  1. $ go run neterrors.go
  2. Timeout
  3. Unknown host
  4. Connection refused

I discover the problem when testing the system in a Windows OS with Portuguese as default language.

[EDIT]

I found a way to do it using the OpError. Here is the checkErr function again with the new approach. If someone has a better solution I will be very glad to known it!

  1. func checkErr(err error) {
  2.   if err == nil {
  3.     println("Ok")
  4.   } else if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
  5.     println("Timeout")
  6.   } else if opError, ok := err.(*net.OpError); ok {
  7.     if opError.Op == "dial" {
  8.       println("Unknown host")
  9.     } else if opError.Op == "read" {
  10.       println("Connection refused")
  11.     }
  12.   }
  13. }

[EDIT2]

Updated after seong answer.

  1. func checkErr(err error) {
  2.   if err == nil {
  3.     println("Ok")
  4.     return
  6.   } else if netError, ok := err.(net.Error); ok && netError.Timeout() {
  7.     println("Timeout")
  8.     return
  9.   }
  11.   switch t := err.(type) {
  12.   case *net.OpError:
  13.     if t.Op == "dial" {
  14.       println("Unknown host")
  15.     } else if t.Op == "read" {
  16.       println("Connection refused")
  17.     }
  19.   case syscall.Errno:
  20.     if t == syscall.ECONNREFUSED {
  21.       println("Connection refused")
  22.     }
  23.   }
  24. }

答案1

得分: 8

net包与您的操作系统密切配合。对于操作系统错误，Go标准库使用syscall包。请参考这里：http://golang.org/pkg/syscall/

net包还可以返回syscall.Errno类型的错误。

对于您的checkErr函数，您可以考虑使用类型开关语句来简化代码（http://golang.org/doc/effective_go.html#type_switch）。

英文:

The net package works closely with your OS. For OS errors, the Go std library uses the pkg syscall. Have a look here: http://golang.org/pkg/syscall/

The net package can also return syscall.Errno type errors.

For a simpler code in you checkErr function, you could consider using a type switch (http://golang.org/doc/effective_go.html#type_switch).

huangapple
  • 本文由 发表于 2014年3月31日 20:29:20
  • 转载请务必保留本文链接：https://go.coder-hub.com/22761562.html
  • error-handling
  • go
  • network-programming
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