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// 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
}
}
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