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112 lines
2.0 KiB
112 lines
2.0 KiB
package main |
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import ( |
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"fmt" |
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"github.com/miekg/dns" |
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"os" |
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) |
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/* |
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dig {-4,-6} +short myip.opendns.com @resolver1.opendns.com |
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dig {-4,-6} TXT +short o-o.myaddr.l.google.com @ns1.google.com |
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*/ |
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func getO() (ipv4 string, ipv6 string) { |
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nameserver := dns.Fqdn("resolver1.opendns.com") + ":53" |
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c := new(dns.Client) |
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m := &dns.Msg{ |
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MsgHdr: dns.MsgHdr{ |
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RecursionDesired: true, |
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}, |
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Question: make([]dns.Question, 1), |
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} |
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// get IPv4 first |
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c.Net = "udp4" |
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m.SetQuestion("myip.opendns.com.", dns.TypeA) |
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r4, _, e4 := c.Exchange(m, nameserver) |
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if e4 != nil { |
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ipv4 = "" |
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} else { |
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ipv4 = getIP(r4.Answer) |
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} |
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// now IPv6 |
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c.Net = "udp6" |
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m.SetQuestion("myip.opendns.com.", dns.TypeAAAA) |
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r6, _, e6 := c.Exchange(m, nameserver) |
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if e6 != nil { |
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ipv6 = "" |
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} else { |
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ipv6 = getIP(r6.Answer) |
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} |
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return ipv4, ipv6 |
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} |
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func getG() (ipv4 string, ipv6 string) { |
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nameserver := dns.Fqdn("ns1.google.com") + ":53" |
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c := new(dns.Client) |
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m := &dns.Msg{ |
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MsgHdr: dns.MsgHdr{ |
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RecursionDesired: true, |
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}, |
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Question: make([]dns.Question, 1), |
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} |
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// get IPv4 first |
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c.Net = "udp4" |
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m.SetQuestion("o-o.myaddr.l.google.com.", dns.TypeTXT) |
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r4, _, e4 := c.Exchange(m, nameserver) |
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if e4 != nil { |
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ipv4 = "" |
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} else { |
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ipv4 = getIP(r4.Answer) |
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} |
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// now IPv6 |
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c.Net = "udp6" |
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m.SetQuestion("o-o.myaddr.l.google.com.", dns.TypeTXT) |
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r6, _, e6 := c.Exchange(m, nameserver) |
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if e6 != nil { |
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ipv6 = "" |
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} else { |
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ipv6 = getIP(r6.Answer) |
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} |
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return ipv4, ipv6 |
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} |
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func getIP(ra []dns.RR) string { |
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//the answer will always be one IP or none |
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var ip string |
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for _, ansa := range ra { |
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switch ansb := ansa.(type) { |
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case *dns.A: |
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ip = ansb.A.String() |
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case *dns.AAAA: |
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ip = ansb.AAAA.String() |
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case *dns.TXT: |
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// we always expect only one IP in the field |
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ip = ansb.Txt[0] |
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} |
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} |
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return ip |
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} |
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func main() { |
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var ipv4, ipv6 string |
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exit := 0 |
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o4, o6 := getO() |
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g4, g6 := getG() |
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if o4 == g4 { |
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ipv4 = o4 |
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} else { |
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ipv4 = "" |
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exit = 111 |
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} |
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if o6 == g6 { |
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ipv6 = o6 |
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} else { |
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ipv6 = "" |
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exit = 111 |
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} |
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fmt.Printf("%s\t%s\n", ipv4, ipv6) |
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os.Exit(exit) |
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}
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