166 lines
6.2 KiB
Go
166 lines
6.2 KiB
Go
// DYNAMIC UPDATES
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//
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// Dynamic updates reuses the DNS message format, but renames the three of
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// the sections. Question is Zone, Answer is Prerequisite, Authority is
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// Update, only the Additional is not renamed. See RFC 2136 for the gory details.
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//
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// You can set a rather complex set of rules for the existence of absence of
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// certain resource records or names in a zone to specify if resource records
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// should be added or removed. The table from RFC 2136 supplemented with the Go
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// DNS function shows which functions exist to specify the prerequisites.
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//
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// 3.2.4 - Table Of Metavalues Used In Prerequisite Section
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//
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// CLASS TYPE RDATA Meaning Function
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// ----------------------------------------------------------------------------
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// ANY ANY empty Name is in use NameUsed
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// ANY rrset empty RRset exists (value independent) RRsetUsedNoRdata
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// NONE ANY empty Name is not in use NameNotUsed
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// NONE rrset empty RRset does not exist RRsetNotUsed
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// zone rrset rr RRset exists (value dependent) RRsetUsedRdata
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//
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// The prerequisite section can also be left empty.
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// If you have decided an the prerequisites you can tell what RRs should
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// be added or deleted. The next table shows the options you have and
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// what function to call.
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// 3.4.2.6 - Table Of Metavalues Used In Update Section
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//
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// CLASS TYPE RDATA Meaning Function
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// -------------------------------------------------------------------------
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// ANY ANY empty Delete all RRsets from a name NameDelete
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// ANY rrset empty Delete an RRset RRsetDelete
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// NONE rrset rr Delete an RR from an RRset RRsetDeleteRR
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// zone rrset rr Add to an RRset RRsetAddRdata
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//
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package dns
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// NewUpdate creates a new DNS update packet, which is a normal DNS message.
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func NewUpdate(zone string, class uint16) *Msg {
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u := new(Msg)
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u.MsgHdr.Response = false
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u.MsgHdr.Opcode = OpcodeUpdate
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u.Compress = false // Seems BIND9 at least cannot handle compressed update pkgs
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u.Question = make([]Question, 1)
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u.Question[0] = Question{zone, TypeSOA, class}
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return u
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}
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// The table from RFC 2136 supplemented with the Go DNS function.
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//
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// 3.2.4 - Table Of Metavalues Used In Prerequisite Section
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//
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// CLASS TYPE RDATA Meaning Function
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// ----------------------------------------------------------------------
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// ANY ANY empty Name is in use NameUsed
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// ANY rrset empty RRset exists (value independent) RRsetUsedNoRdata
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// NONE ANY empty Name is not in use NameNotUsed
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// NONE rrset empty RRset does not exist RRsetNotUsed
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// zone rrset rr RRset exists (value dependent) RRsetUsedRdata
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// NameUsed sets the RRs in the prereq section to
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// "Name is in use" RRs. RFC 2136 section 2.4.4.
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func (u *Msg) NameUsed(rr []RR) {
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u.Answer = make([]RR, len(rr))
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for i, r := range rr {
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u.Answer[i] = &RR_ANY{Hdr: RR_Header{Name: r.Header().Name, Ttl: 0, Rrtype: TypeANY, Class: ClassANY}}
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}
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}
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// NameNotUsed sets the RRs in the prereq section to
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// "Name is in not use" RRs. RFC 2136 section 2.4.5.
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func (u *Msg) NameNotUsed(rr []RR) {
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u.Answer = make([]RR, len(rr))
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for i, r := range rr {
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u.Answer[i] = &RR_ANY{Hdr: RR_Header{Name: r.Header().Name, Ttl: 0, Rrtype: TypeANY, Class: ClassNONE}}
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}
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}
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// RRsetUsedRdata sets the RRs in the prereq section to
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// "RRset exists (value dependent -- with rdata)" RRs. RFC 2136 section 2.4.2.
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func (u *Msg) RRsetUsedRdata(rr []RR) {
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if len(u.Question) == 0 {
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panic("empty question section")
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}
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u.Answer = make([]RR, len(rr))
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for i, r := range rr {
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u.Answer[i] = r
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u.Answer[i].Header().Class = u.Question[0].Qclass
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}
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}
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// RRsetUsedNoRdata sets the RRs in the prereq section to
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// "RRset exists (value independent -- no rdata)" RRs. RFC 2136 section 2.4.1.
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func (u *Msg) RRsetUsedNoRdata(rr []RR) {
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u.Answer = make([]RR, len(rr))
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for i, r := range rr {
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u.Answer[i] = r
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u.Answer[i].Header().Class = ClassANY
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u.Answer[i].Header().Ttl = 0
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u.Answer[i].Header().Rdlength = 0
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}
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}
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// RRsetNotUsed sets the RRs in the prereq section to
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// "RRset does not exist" RRs. RFC 2136 section 2.4.3.
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func (u *Msg) RRsetNotUsed(rr []RR) {
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u.Answer = make([]RR, len(rr))
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for i, r := range rr {
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u.Answer[i] = r
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u.Answer[i].Header().Class = ClassNONE
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u.Answer[i].Header().Rdlength = 0
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u.Answer[i].Header().Ttl = 0
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}
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}
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// The table from RFC 2136 supplemented with the Go DNS function.
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//
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// 3.4.2.6 - Table Of Metavalues Used In Update Section
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//
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// CLASS TYPE RDATA Meaning Function
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// --------------------------------------------------------------------------
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// ANY ANY empty Delete all RRsets from a name NameDelete
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// ANY rrset empty Delete an RRset RRsetDelete
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// NONE rrset rr Delete an RR from an RRset RRsetDeleteRR
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// zone rrset rr Add to an RRset RRsetAddRdata
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// RRsetAddRdata adds an complete RRset, see RFC 2136 section 2.5.1
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func (u *Msg) RRsetAddRdata(rr []RR) {
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if len(u.Question) == 0 {
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panic("empty question section")
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}
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u.Ns = make([]RR, len(rr))
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for i, r := range rr {
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u.Ns[i] = r
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u.Ns[i].Header().Class = u.Question[0].Qclass
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}
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}
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// RRsetDelete deletes an RRset, see RFC 2136 section 2.5.2
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func (u *Msg) RRsetDelete(rr []RR) {
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u.Ns = make([]RR, len(rr))
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for i, r := range rr {
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u.Ns[i] = r
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u.Ns[i].Header().Class = ClassANY
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u.Ns[i].Header().Rdlength = 0
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u.Ns[i].Header().Ttl = 0
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}
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}
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// NameDelete deletes all RRsets of a name, see RFC 2136 section 2.5.3
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func (u *Msg) NameDelete(rr []RR) {
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u.Ns = make([]RR, len(rr))
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for i, r := range rr {
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u.Ns[i] = &RR_ANY{Hdr: RR_Header{Name: r.Header().Name, Ttl: 0, Rrtype: TypeANY, Class: ClassANY}}
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}
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}
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// RRsetDeleteRR deletes RR from the RRSset, see RFC 2136 section 2.5.4
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func (u *Msg) RRsetDeleteRR(rr []RR) {
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u.Ns = make([]RR, len(rr))
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for i, r := range rr {
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u.Ns[i] = r
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u.Ns[i].Header().Class = ClassNONE
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u.Ns[i].Header().Ttl = 0
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}
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}
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