24 lines
614 B
Go
24 lines
614 B
Go
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package upstream
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import "github.com/miekg/dns"
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// Performs a simple health-check of the specified upstream
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func IsAlive(u Upstream) (bool, error) {
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// Using ipv4only.arpa. domain as it is a part of DNS64 RFC and it should exist everywhere
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ping := new(dns.Msg)
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ping.SetQuestion("ipv4only.arpa.", dns.TypeA)
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resp, err := u.Exchange(nil, ping)
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// If we got a header, we're alright, basically only care about I/O errors 'n stuff.
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if err != nil && resp != nil {
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// Silly check, something sane came back.
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if resp.Response || resp.Opcode == dns.OpcodeQuery {
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err = nil
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}
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}
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return err == nil, err
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}
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