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