| // Copyright 2011 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // +build darwin freebsd linux netbsd openbsd |
| |
| package dns |
| |
| import ( |
| "net" |
| ) |
| |
| // LookupSRV tries to resolve an SRV query of the given service, |
| // protocol, and domain name. The proto is "tcp" or "udp". |
| // The returned records are sorted by priority and randomized |
| // by weight within a priority. |
| // |
| // LookupSRV constructs the DNS name to look up following RFC 2782. |
| // That is, it looks up _service._proto.name. To accommodate services |
| // publishing SRV records under non-standard names, if both service |
| // and proto are empty strings, LookupSRV looks up name directly. |
| func LookupSRV(service, proto, name string) (cname string, addrs []*net.SRV, err error) { |
| var target string |
| if service == "" && proto == "" { |
| target = name |
| } else { |
| target = "_" + service + "._" + proto + "." + name |
| } |
| var records []RR |
| cname, records, err = lookup(target, TypeSRV) |
| if err != nil { |
| return |
| } |
| addrs = make([]*net.SRV, len(records)) |
| for i, rr := range records { |
| r := rr.(*RR_SRV) |
| addrs[i] = &net.SRV{r.Target, r.Port, r.Priority, r.Weight} |
| } |
| byPriorityWeight(addrs).sort() |
| return |
| } |
| |
| // LookupMX returns the DNS MX records for the given domain name sorted by preference. |
| func LookupMX(name string) (mx []*net.MX, err error) { |
| _, records, err := lookup(name, TypeMX) |
| if err != nil { |
| return |
| } |
| mx = make([]*net.MX, len(records)) |
| for i, rr := range records { |
| r := rr.(*RR_MX) |
| mx[i] = &net.MX{r.Mx, r.Pref} |
| } |
| byPref(mx).sort() |
| return |
| } |
| |
| // LookupTXT returns the DNS TXT records for the given domain name. |
| func LookupTXT(name string) (txt []string, err error) { |
| _, records, err := lookup(name, TypeTXT) |
| if err != nil { |
| return |
| } |
| for _, r := range records { |
| txt = append(txt, r.(*RR_TXT).Txt...) |
| } |
| return |
| } |
| |
| // LookupAddr performs a reverse lookup for the given address, returning a list |
| // of names mapping to that address. |
| func LookupAddr(addr string) (name []string, err error) { |
| name = lookupStaticAddr(addr) |
| if len(name) > 0 { |
| return |
| } |
| var arpa string |
| arpa, err = reverseaddr(addr) |
| if err != nil { |
| return |
| } |
| var records []RR |
| _, records, err = lookup(arpa, TypePTR) |
| if err != nil { |
| return |
| } |
| name = make([]string, len(records)) |
| for i := range records { |
| r := records[i].(*RR_PTR) |
| name[i] = r.Ptr |
| } |
| return |
| } |
