79 lines
1.5 KiB
Go
79 lines
1.5 KiB
Go
// Package dns resolves names to dns records
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package dns
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import (
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"context"
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"net"
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"github.com/micro/go-micro/v3/network/resolver"
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"github.com/miekg/dns"
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)
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// Resolver is a DNS network resolve
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type Resolver struct {
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// The resolver address to use
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Address string
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}
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// Resolve assumes ID is a domain name e.g micro.mu
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func (r *Resolver) Resolve(name string) ([]*resolver.Record, error) {
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host, port, err := net.SplitHostPort(name)
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if err != nil {
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host = name
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port = "8085"
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}
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if len(host) == 0 {
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host = "localhost"
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}
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if len(r.Address) == 0 {
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r.Address = "1.0.0.1:53"
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}
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//nolint:prealloc
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var records []*resolver.Record
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// parsed an actual ip
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if v := net.ParseIP(host); v != nil {
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records = append(records, &resolver.Record{
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Address: net.JoinHostPort(host, port),
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})
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return records, nil
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}
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m := new(dns.Msg)
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m.SetQuestion(dns.Fqdn(host), dns.TypeA)
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rec, err := dns.ExchangeContext(context.Background(), m, r.Address)
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if err != nil {
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return nil, err
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}
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for _, answer := range rec.Answer {
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h := answer.Header()
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// check record type matches
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if h.Rrtype != dns.TypeA {
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continue
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}
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arec, _ := answer.(*dns.A)
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addr := arec.A.String()
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// join resolved record with port
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address := net.JoinHostPort(addr, port)
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// append to record set
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records = append(records, &resolver.Record{
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Address: address,
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})
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}
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// no records returned so just best effort it
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if len(records) == 0 {
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records = append(records, &resolver.Record{
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Address: net.JoinHostPort(host, port),
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})
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}
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return records, nil
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}
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