// Package dns resolves names to dns records package dns // import "go.unistack.org/micro/v4/resolver/dns" import ( "context" "net" "sync" "time" "go.unistack.org/micro/v4/resolver" ) // Resolver is a DNS network resolve type Resolver struct { sync.RWMutex goresolver *net.Resolver Address string } // Resolve tries to resolve endpoint address 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 = "1.1.1.1:53" } // parsed an actual ip if v := net.ParseIP(host); v != nil { rec := &resolver.Record{Address: net.JoinHostPort(host, port)} return []*resolver.Record{rec}, nil } r.RLock() goresolver := r.goresolver r.RUnlock() if goresolver == nil { r.Lock() r.goresolver = &net.Resolver{ Dial: func(ctx context.Context, _ string, _ string) (net.Conn, error) { d := net.Dialer{ Timeout: time.Millisecond * time.Duration(100), } return d.DialContext(ctx, "udp", r.Address) }, } r.Unlock() } addrs, err := goresolver.LookupIP(context.TODO(), "ip", host) if err != nil { return nil, err } if len(addrs) == 0 { rec := &resolver.Record{Address: net.JoinHostPort(host, port)} return []*resolver.Record{rec}, nil } records := make([]*resolver.Record, 0, len(addrs)) for _, addr := range addrs { records = append(records, &resolver.Record{ Address: net.JoinHostPort(addr.String(), port), }) } return records, nil }