// Copyright 2011 Miek Gieben. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // DYNAMIC UPDATES // // Dynamic updates reuses the DNS message format, but renames three of // the sections. Question is Zone, Answer is Prerequisite, Authority is // Update, only the Additional is not renamed. See RFC 2136 for the gory details. // // You can set a rather complex set of rules for the existence of absence of // certain resource records or names in a zone to specify if resource records // should be added or removed. The table from RFC 2136 supplemented with the Go // DNS function shows which functions exist to specify the prerequisites. // // 3.2.4 - Table Of Metavalues Used In Prerequisite Section // // CLASS TYPE RDATA Meaning Function // -------------------------------------------------------------- // ANY ANY empty Name is in use NameUsed // ANY rrset empty RRset exists (value indep) RRsetUsed // NONE ANY empty Name is not in use NameNotUsed // NONE rrset empty RRset does not exist RRsetNotUsed // zone rrset rr RRset exists (value dep) Used // // The prerequisite section can also be left empty. // If you have decided on the prerequisites you can tell what RRs should // be added or deleted. The next table shows the options you have and // what functions to call. // // 3.4.2.6 - Table Of Metavalues Used In Update Section // // CLASS TYPE RDATA Meaning Function // --------------------------------------------------------------- // ANY ANY empty Delete all RRsets from name RemoveName // ANY rrset empty Delete an RRset RemoveRRset // NONE rrset rr Delete an RR from RRset Remove // zone rrset rr Add to an RRset Insert // package dns // NameUsed sets the RRs in the prereq section to // "Name is in use" RRs. RFC 2136 section 2.4.4. func (u *Msg) NameUsed(rr []RR) { u.Answer = make([]RR, len(rr)) for i, r := range rr { u.Answer[i] = &ANY{Hdr: RR_Header{Name: r.Header().Name, Ttl: 0, Rrtype: TypeANY, Class: ClassANY}} } } // NameNotUsed sets the RRs in the prereq section to // "Name is in not use" RRs. RFC 2136 section 2.4.5. func (u *Msg) NameNotUsed(rr []RR) { u.Answer = make([]RR, len(rr)) for i, r := range rr { u.Answer[i] = &ANY{Hdr: RR_Header{Name: r.Header().Name, Ttl: 0, Rrtype: TypeANY, Class: ClassNONE}} } } // Used sets the RRs in the prereq section to // "RRset exists (value dependent -- with rdata)" RRs. RFC 2136 section 2.4.2. func (u *Msg) Used(rr []RR) { if len(u.Question) == 0 { panic("dns: empty question section") } u.Answer = make([]RR, len(rr)) for i, r := range rr { u.Answer[i] = r u.Answer[i].Header().Class = u.Question[0].Qclass } } // RRsetUsed sets the RRs in the prereq section to // "RRset exists (value independent -- no rdata)" RRs. RFC 2136 section 2.4.1. func (u *Msg) RRsetUsed(rr []RR) { u.Answer = make([]RR, len(rr)) for i, r := range rr { u.Answer[i] = r u.Answer[i].Header().Class = ClassANY u.Answer[i].Header().Ttl = 0 u.Answer[i].Header().Rdlength = 0 } } // RRsetNotUsed sets the RRs in the prereq section to // "RRset does not exist" RRs. RFC 2136 section 2.4.3. func (u *Msg) RRsetNotUsed(rr []RR) { u.Answer = make([]RR, len(rr)) for i, r := range rr { u.Answer[i] = r u.Answer[i].Header().Class = ClassNONE u.Answer[i].Header().Rdlength = 0 u.Answer[i].Header().Ttl = 0 } } // Insert creates a dynamic update packet that adds an complete RRset, see RFC 2136 section 2.5.1. func (u *Msg) Insert(rr []RR) { if len(u.Question) == 0 { panic("dns: empty question section") } u.Ns = make([]RR, len(rr)) for i, r := range rr { u.Ns[i] = r u.Ns[i].Header().Class = u.Question[0].Qclass } } // RemoveRRset creates a dynamic update packet that deletes an RRset, see RFC 2136 section 2.5.2. func (u *Msg) RemoveRRset(rr []RR) { u.Ns = make([]RR, len(rr)) for i, r := range rr { u.Ns[i] = r u.Ns[i].Header().Class = ClassANY u.Ns[i].Header().Rdlength = 0 u.Ns[i].Header().Ttl = 0 } } // RemoveName creates a dynamic update packet that deletes all RRsets of a name, see RFC 2136 section 2.5.3 func (u *Msg) RemoveName(rr []RR) { u.Ns = make([]RR, len(rr)) for i, r := range rr { u.Ns[i] = &ANY{Hdr: RR_Header{Name: r.Header().Name, Ttl: 0, Rrtype: TypeANY, Class: ClassANY}} } } // Remove creates a dynamic update packet deletes RR from the RRSset, see RFC 2136 section 2.5.4 func (u *Msg) Remove(rr []RR) { u.Ns = make([]RR, len(rr)) for i, r := range rr { u.Ns[i] = r u.Ns[i].Header().Class = ClassNONE u.Ns[i].Header().Ttl = 0 } }