diff --git a/edns.go b/edns.go
index 87c8affe..2732c173 100644
--- a/edns.go
+++ b/edns.go
@@ -30,11 +30,6 @@ type OPT struct {
 	Option []EDNS0 `dns:"opt"`
 }
 
-// Header implements the RR interface.
-func (rr *OPT) Header() *RR_Header {
-	return &rr.Hdr
-}
-
 func (rr *OPT) String() string {
 	s := "\n;; OPT PSEUDOSECTION:\n; EDNS: version " + strconv.Itoa(int(rr.Version())) + "; "
 	if rr.Do() {
diff --git a/msg.go b/msg.go
index 3d13135c..96d69a24 100644
--- a/msg.go
+++ b/msg.go
@@ -89,84 +89,6 @@ type Msg struct {
 	Extra    []RR       // Holds the RR(s) of the additional section.
 }
 
-// TypeToString is a map of strings for each RR wire type.
-var TypeToString = map[uint16]string{
-	TypeA:          "A",
-	TypeAAAA:       "AAAA",
-	TypeAFSDB:      "AFSDB",
-	TypeANY:        "ANY", // Meta RR
-	TypeATMA:       "ATMA",
-	TypeAXFR:       "AXFR", // Meta RR
-	TypeCAA:        "CAA",
-	TypeCDNSKEY:    "CDNSKEY",
-	TypeCDS:        "CDS",
-	TypeCERT:       "CERT",
-	TypeCNAME:      "CNAME",
-	TypeDHCID:      "DHCID",
-	TypeDLV:        "DLV",
-	TypeDNAME:      "DNAME",
-	TypeDNSKEY:     "DNSKEY",
-	TypeDS:         "DS",
-	TypeEID:        "EID",
-	TypeEUI48:      "EUI48",
-	TypeEUI64:      "EUI64",
-	TypeGID:        "GID",
-	TypeGPOS:       "GPOS",
-	TypeHINFO:      "HINFO",
-	TypeHIP:        "HIP",
-	TypeIPSECKEY:   "IPSECKEY",
-	TypeISDN:       "ISDN",
-	TypeIXFR:       "IXFR", // Meta RR
-	TypeKEY:        "KEY",
-	TypeKX:         "KX",
-	TypeL32:        "L32",
-	TypeL64:        "L64",
-	TypeLOC:        "LOC",
-	TypeLP:         "LP",
-	TypeMB:         "MB",
-	TypeMD:         "MD",
-	TypeMF:         "MF",
-	TypeMG:         "MG",
-	TypeMINFO:      "MINFO",
-	TypeMR:         "MR",
-	TypeMX:         "MX",
-	TypeNAPTR:      "NAPTR",
-	TypeNID:        "NID",
-	TypeNINFO:      "NINFO",
-	TypeNIMLOC:     "NIMLOC",
-	TypeNS:         "NS",
-	TypeNSAPPTR:    "NSAP-PTR",
-	TypeNSEC3:      "NSEC3",
-	TypeNSEC3PARAM: "NSEC3PARAM",
-	TypeNSEC:       "NSEC",
-	TypeNULL:       "NULL",
-	TypeOPT:        "OPT",
-	TypeOPENPGPKEY: "OPENPGPKEY",
-	TypePTR:        "PTR",
-	TypeRKEY:       "RKEY",
-	TypeRP:         "RP",
-	TypeRRSIG:      "RRSIG",
-	TypeRT:         "RT",
-	TypeSIG:        "SIG",
-	TypeSOA:        "SOA",
-	TypeSPF:        "SPF",
-	TypeSRV:        "SRV",
-	TypeSSHFP:      "SSHFP",
-	TypeTA:         "TA",
-	TypeTALINK:     "TALINK",
-	TypeTKEY:       "TKEY", // Meta RR
-	TypeTLSA:       "TLSA",
-	TypeTSIG:       "TSIG", // Meta RR
-	TypeTXT:        "TXT",
-	TypePX:         "PX",
-	TypeUID:        "UID",
-	TypeUINFO:      "UINFO",
-	TypeUNSPEC:     "UNSPEC",
-	TypeURI:        "URI",
-	TypeWKS:        "WKS",
-	TypeX25:        "X25",
-}
-
 // StringToType is the reverse of TypeToString, needed for string parsing.
 var StringToType = reverseInt16(TypeToString)
 
diff --git a/tsig.go b/tsig.go
index d7bc2505..be7f86af 100644
--- a/tsig.go
+++ b/tsig.go
@@ -37,10 +37,6 @@ type TSIG struct {
 	OtherData  string `dns:"size-hex"`
 }
 
-func (rr *TSIG) Header() *RR_Header {
-	return &rr.Hdr
-}
-
 // TSIG has no official presentation format, but this will suffice.
 
 func (rr *TSIG) String() string {
@@ -58,11 +54,6 @@ func (rr *TSIG) String() string {
 	return s
 }
 
-func (rr *TSIG) len() int {
-	return rr.Hdr.len() + len(rr.Algorithm) + 1 + 6 +
-		4 + len(rr.MAC)/2 + 1 + 6 + len(rr.OtherData)/2 + 1
-}
-
 func (rr *TSIG) copy() RR {
 	return &TSIG{*rr.Hdr.copyHeader(), rr.Algorithm, rr.TimeSigned, rr.Fudge, rr.MACSize, rr.MAC, rr.OrigId, rr.Error, rr.OtherLen, rr.OtherData}
 }
diff --git a/types.go b/types.go
index d4f384b3..2ade8a77 100644
--- a/types.go
+++ b/types.go
@@ -206,6 +206,8 @@ var CertTypeToString = map[uint16]string{
 // StringToCertType is the reverseof CertTypeToString.
 var StringToCertType = reverseInt16(CertTypeToString)
 
+//go:generate go run types_generate.go
+
 // Question holds a DNS question. There can be multiple questions in the
 // question section of a message. Usually there is just one.
 type Question struct {
@@ -214,6 +216,10 @@ type Question struct {
 	Qclass uint16
 }
 
+func (q *Question) len() int {
+	return len(q.Name) + 1 + 2 + 2
+}
+
 func (q *Question) String() (s string) {
 	// prefix with ; (as in dig)
 	s = ";" + sprintName(q.Name) + "\t"
@@ -222,11 +228,6 @@ func (q *Question) String() (s string) {
 	return s
 }
 
-func (q *Question) len() int {
-	l := len(q.Name) + 1
-	return l + 4
-}
-
 // ANY is a wildcard record. See RFC 1035, Section 3.2.3. ANY
 // is named "*" there.
 type ANY struct {
@@ -234,20 +235,16 @@ type ANY struct {
 	// Does not have any rdata
 }
 
-func (rr *ANY) Header() *RR_Header { return &rr.Hdr }
-func (rr *ANY) copy() RR           { return &ANY{*rr.Hdr.copyHeader()} }
-func (rr *ANY) String() string     { return rr.Hdr.String() }
-func (rr *ANY) len() int           { return rr.Hdr.len() }
+func (rr *ANY) copy() RR       { return &ANY{*rr.Hdr.copyHeader()} }
+func (rr *ANY) String() string { return rr.Hdr.String() }
 
 type CNAME struct {
 	Hdr    RR_Header
 	Target string `dns:"cdomain-name"`
 }
 
-func (rr *CNAME) Header() *RR_Header { return &rr.Hdr }
-func (rr *CNAME) copy() RR           { return &CNAME{*rr.Hdr.copyHeader(), sprintName(rr.Target)} }
-func (rr *CNAME) String() string     { return rr.Hdr.String() + rr.Target }
-func (rr *CNAME) len() int           { return rr.Hdr.len() + len(rr.Target) + 1 }
+func (rr *CNAME) copy() RR       { return &CNAME{*rr.Hdr.copyHeader(), sprintName(rr.Target)} }
+func (rr *CNAME) String() string { return rr.Hdr.String() + rr.Target }
 
 type HINFO struct {
 	Hdr RR_Header
@@ -255,33 +252,27 @@ type HINFO struct {
 	Os  string
 }
 
-func (rr *HINFO) Header() *RR_Header { return &rr.Hdr }
-func (rr *HINFO) copy() RR           { return &HINFO{*rr.Hdr.copyHeader(), rr.Cpu, rr.Os} }
+func (rr *HINFO) copy() RR { return &HINFO{*rr.Hdr.copyHeader(), rr.Cpu, rr.Os} }
 func (rr *HINFO) String() string {
 	return rr.Hdr.String() + sprintTxt([]string{rr.Cpu, rr.Os})
 }
-func (rr *HINFO) len() int { return rr.Hdr.len() + len(rr.Cpu) + 1 + len(rr.Os) + 1 }
 
 type MB struct {
 	Hdr RR_Header
 	Mb  string `dns:"cdomain-name"`
 }
 
-func (rr *MB) Header() *RR_Header { return &rr.Hdr }
-func (rr *MB) copy() RR           { return &MB{*rr.Hdr.copyHeader(), sprintName(rr.Mb)} }
+func (rr *MB) copy() RR { return &MB{*rr.Hdr.copyHeader(), sprintName(rr.Mb)} }
 
 func (rr *MB) String() string { return rr.Hdr.String() + rr.Mb }
-func (rr *MB) len() int       { return rr.Hdr.len() + len(rr.Mb) + 1 }
 
 type MG struct {
 	Hdr RR_Header
 	Mg  string `dns:"cdomain-name"`
 }
 
-func (rr *MG) Header() *RR_Header { return &rr.Hdr }
-func (rr *MG) copy() RR           { return &MG{*rr.Hdr.copyHeader(), rr.Mg} }
-func (rr *MG) len() int           { l := len(rr.Mg) + 1; return rr.Hdr.len() + l }
-func (rr *MG) String() string     { return rr.Hdr.String() + sprintName(rr.Mg) }
+func (rr *MG) copy() RR       { return &MG{*rr.Hdr.copyHeader(), rr.Mg} }
+func (rr *MG) String() string { return rr.Hdr.String() + sprintName(rr.Mg) }
 
 type MINFO struct {
 	Hdr   RR_Header
@@ -289,27 +280,18 @@ type MINFO struct {
 	Email string `dns:"cdomain-name"`
 }
 
-func (rr *MINFO) Header() *RR_Header { return &rr.Hdr }
-func (rr *MINFO) copy() RR           { return &MINFO{*rr.Hdr.copyHeader(), rr.Rmail, rr.Email} }
+func (rr *MINFO) copy() RR { return &MINFO{*rr.Hdr.copyHeader(), rr.Rmail, rr.Email} }
 
 func (rr *MINFO) String() string {
 	return rr.Hdr.String() + sprintName(rr.Rmail) + " " + sprintName(rr.Email)
 }
 
-func (rr *MINFO) len() int {
-	l := len(rr.Rmail) + 1
-	n := len(rr.Email) + 1
-	return rr.Hdr.len() + l + n
-}
-
 type MR struct {
 	Hdr RR_Header
 	Mr  string `dns:"cdomain-name"`
 }
 
-func (rr *MR) Header() *RR_Header { return &rr.Hdr }
-func (rr *MR) copy() RR           { return &MR{*rr.Hdr.copyHeader(), rr.Mr} }
-func (rr *MR) len() int           { l := len(rr.Mr) + 1; return rr.Hdr.len() + l }
+func (rr *MR) copy() RR { return &MR{*rr.Hdr.copyHeader(), rr.Mr} }
 
 func (rr *MR) String() string {
 	return rr.Hdr.String() + sprintName(rr.Mr)
@@ -320,9 +302,7 @@ type MF struct {
 	Mf  string `dns:"cdomain-name"`
 }
 
-func (rr *MF) Header() *RR_Header { return &rr.Hdr }
-func (rr *MF) copy() RR           { return &MF{*rr.Hdr.copyHeader(), rr.Mf} }
-func (rr *MF) len() int           { return rr.Hdr.len() + len(rr.Mf) + 1 }
+func (rr *MF) copy() RR { return &MF{*rr.Hdr.copyHeader(), rr.Mf} }
 
 func (rr *MF) String() string {
 	return rr.Hdr.String() + sprintName(rr.Mf)
@@ -333,9 +313,7 @@ type MD struct {
 	Md  string `dns:"cdomain-name"`
 }
 
-func (rr *MD) Header() *RR_Header { return &rr.Hdr }
-func (rr *MD) copy() RR           { return &MD{*rr.Hdr.copyHeader(), rr.Md} }
-func (rr *MD) len() int           { return rr.Hdr.len() + len(rr.Md) + 1 }
+func (rr *MD) copy() RR { return &MD{*rr.Hdr.copyHeader(), rr.Md} }
 
 func (rr *MD) String() string {
 	return rr.Hdr.String() + sprintName(rr.Md)
@@ -347,9 +325,7 @@ type MX struct {
 	Mx         string `dns:"cdomain-name"`
 }
 
-func (rr *MX) Header() *RR_Header { return &rr.Hdr }
-func (rr *MX) copy() RR           { return &MX{*rr.Hdr.copyHeader(), rr.Preference, rr.Mx} }
-func (rr *MX) len() int           { l := len(rr.Mx) + 1; return rr.Hdr.len() + l + 2 }
+func (rr *MX) copy() RR { return &MX{*rr.Hdr.copyHeader(), rr.Preference, rr.Mx} }
 
 func (rr *MX) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Preference)) + " " + sprintName(rr.Mx)
@@ -361,9 +337,7 @@ type AFSDB struct {
 	Hostname string `dns:"cdomain-name"`
 }
 
-func (rr *AFSDB) Header() *RR_Header { return &rr.Hdr }
-func (rr *AFSDB) copy() RR           { return &AFSDB{*rr.Hdr.copyHeader(), rr.Subtype, rr.Hostname} }
-func (rr *AFSDB) len() int           { l := len(rr.Hostname) + 1; return rr.Hdr.len() + l + 2 }
+func (rr *AFSDB) copy() RR { return &AFSDB{*rr.Hdr.copyHeader(), rr.Subtype, rr.Hostname} }
 
 func (rr *AFSDB) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Subtype)) + " " + sprintName(rr.Hostname)
@@ -374,9 +348,7 @@ type X25 struct {
 	PSDNAddress string
 }
 
-func (rr *X25) Header() *RR_Header { return &rr.Hdr }
-func (rr *X25) copy() RR           { return &X25{*rr.Hdr.copyHeader(), rr.PSDNAddress} }
-func (rr *X25) len() int           { return rr.Hdr.len() + len(rr.PSDNAddress) + 1 }
+func (rr *X25) copy() RR { return &X25{*rr.Hdr.copyHeader(), rr.PSDNAddress} }
 
 func (rr *X25) String() string {
 	return rr.Hdr.String() + rr.PSDNAddress
@@ -388,9 +360,7 @@ type RT struct {
 	Host       string `dns:"cdomain-name"`
 }
 
-func (rr *RT) Header() *RR_Header { return &rr.Hdr }
-func (rr *RT) copy() RR           { return &RT{*rr.Hdr.copyHeader(), rr.Preference, rr.Host} }
-func (rr *RT) len() int           { l := len(rr.Host) + 1; return rr.Hdr.len() + l + 2 }
+func (rr *RT) copy() RR { return &RT{*rr.Hdr.copyHeader(), rr.Preference, rr.Host} }
 
 func (rr *RT) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Preference)) + " " + sprintName(rr.Host)
@@ -401,9 +371,7 @@ type NS struct {
 	Ns  string `dns:"cdomain-name"`
 }
 
-func (rr *NS) Header() *RR_Header { return &rr.Hdr }
-func (rr *NS) len() int           { l := len(rr.Ns) + 1; return rr.Hdr.len() + l }
-func (rr *NS) copy() RR           { return &NS{*rr.Hdr.copyHeader(), rr.Ns} }
+func (rr *NS) copy() RR { return &NS{*rr.Hdr.copyHeader(), rr.Ns} }
 
 func (rr *NS) String() string {
 	return rr.Hdr.String() + sprintName(rr.Ns)
@@ -414,9 +382,7 @@ type PTR struct {
 	Ptr string `dns:"cdomain-name"`
 }
 
-func (rr *PTR) Header() *RR_Header { return &rr.Hdr }
-func (rr *PTR) copy() RR           { return &PTR{*rr.Hdr.copyHeader(), rr.Ptr} }
-func (rr *PTR) len() int           { l := len(rr.Ptr) + 1; return rr.Hdr.len() + l }
+func (rr *PTR) copy() RR { return &PTR{*rr.Hdr.copyHeader(), rr.Ptr} }
 
 func (rr *PTR) String() string {
 	return rr.Hdr.String() + sprintName(rr.Ptr)
@@ -428,9 +394,7 @@ type RP struct {
 	Txt  string `dns:"domain-name"`
 }
 
-func (rr *RP) Header() *RR_Header { return &rr.Hdr }
-func (rr *RP) copy() RR           { return &RP{*rr.Hdr.copyHeader(), rr.Mbox, rr.Txt} }
-func (rr *RP) len() int           { return rr.Hdr.len() + len(rr.Mbox) + 1 + len(rr.Txt) + 1 }
+func (rr *RP) copy() RR { return &RP{*rr.Hdr.copyHeader(), rr.Mbox, rr.Txt} }
 
 func (rr *RP) String() string {
 	return rr.Hdr.String() + rr.Mbox + " " + sprintTxt([]string{rr.Txt})
@@ -447,7 +411,6 @@ type SOA struct {
 	Minttl  uint32
 }
 
-func (rr *SOA) Header() *RR_Header { return &rr.Hdr }
 func (rr *SOA) copy() RR {
 	return &SOA{*rr.Hdr.copyHeader(), rr.Ns, rr.Mbox, rr.Serial, rr.Refresh, rr.Retry, rr.Expire, rr.Minttl}
 }
@@ -461,18 +424,11 @@ func (rr *SOA) String() string {
 		" " + strconv.FormatInt(int64(rr.Minttl), 10)
 }
 
-func (rr *SOA) len() int {
-	l := len(rr.Ns) + 1
-	n := len(rr.Mbox) + 1
-	return rr.Hdr.len() + l + n + 20
-}
-
 type TXT struct {
 	Hdr RR_Header
 	Txt []string `dns:"txt"`
 }
 
-func (rr *TXT) Header() *RR_Header { return &rr.Hdr }
 func (rr *TXT) copy() RR {
 	cp := make([]string, len(rr.Txt), cap(rr.Txt))
 	copy(cp, rr.Txt)
@@ -621,20 +577,11 @@ func nextByte(b []byte, offset int) (byte, int) {
 	}
 }
 
-func (rr *TXT) len() int {
-	l := rr.Hdr.len()
-	for _, t := range rr.Txt {
-		l += len(t) + 1
-	}
-	return l
-}
-
 type SPF struct {
 	Hdr RR_Header
 	Txt []string `dns:"txt"`
 }
 
-func (rr *SPF) Header() *RR_Header { return &rr.Hdr }
 func (rr *SPF) copy() RR {
 	cp := make([]string, len(rr.Txt), cap(rr.Txt))
 	copy(cp, rr.Txt)
@@ -643,14 +590,6 @@ func (rr *SPF) copy() RR {
 
 func (rr *SPF) String() string { return rr.Hdr.String() + sprintTxt(rr.Txt) }
 
-func (rr *SPF) len() int {
-	l := rr.Hdr.len()
-	for _, t := range rr.Txt {
-		l += len(t) + 1
-	}
-	return l
-}
-
 type SRV struct {
 	Hdr      RR_Header
 	Priority uint16
@@ -659,8 +598,6 @@ type SRV struct {
 	Target   string `dns:"domain-name"`
 }
 
-func (rr *SRV) Header() *RR_Header { return &rr.Hdr }
-func (rr *SRV) len() int           { l := len(rr.Target) + 1; return rr.Hdr.len() + l + 6 }
 func (rr *SRV) copy() RR {
 	return &SRV{*rr.Hdr.copyHeader(), rr.Priority, rr.Weight, rr.Port, rr.Target}
 }
@@ -682,7 +619,6 @@ type NAPTR struct {
 	Replacement string `dns:"domain-name"`
 }
 
-func (rr *NAPTR) Header() *RR_Header { return &rr.Hdr }
 func (rr *NAPTR) copy() RR {
 	return &NAPTR{*rr.Hdr.copyHeader(), rr.Order, rr.Preference, rr.Flags, rr.Service, rr.Regexp, rr.Replacement}
 }
@@ -697,11 +633,6 @@ func (rr *NAPTR) String() string {
 		rr.Replacement
 }
 
-func (rr *NAPTR) len() int {
-	return rr.Hdr.len() + 4 + len(rr.Flags) + 1 + len(rr.Service) + 1 +
-		len(rr.Regexp) + 1 + len(rr.Replacement) + 1
-}
-
 // The CERT resource record, see RFC 4398.
 type CERT struct {
 	Hdr         RR_Header
@@ -711,7 +642,6 @@ type CERT struct {
 	Certificate string `dns:"base64"`
 }
 
-func (rr *CERT) Header() *RR_Header { return &rr.Hdr }
 func (rr *CERT) copy() RR {
 	return &CERT{*rr.Hdr.copyHeader(), rr.Type, rr.KeyTag, rr.Algorithm, rr.Certificate}
 }
@@ -733,20 +663,13 @@ func (rr *CERT) String() string {
 		" " + rr.Certificate
 }
 
-func (rr *CERT) len() int {
-	return rr.Hdr.len() + 5 +
-		base64.StdEncoding.DecodedLen(len(rr.Certificate))
-}
-
 // The DNAME resource record, see RFC 2672.
 type DNAME struct {
 	Hdr    RR_Header
 	Target string `dns:"domain-name"`
 }
 
-func (rr *DNAME) Header() *RR_Header { return &rr.Hdr }
-func (rr *DNAME) copy() RR           { return &DNAME{*rr.Hdr.copyHeader(), rr.Target} }
-func (rr *DNAME) len() int           { l := len(rr.Target) + 1; return rr.Hdr.len() + l }
+func (rr *DNAME) copy() RR { return &DNAME{*rr.Hdr.copyHeader(), rr.Target} }
 
 func (rr *DNAME) String() string {
 	return rr.Hdr.String() + sprintName(rr.Target)
@@ -757,9 +680,7 @@ type A struct {
 	A   net.IP `dns:"a"`
 }
 
-func (rr *A) Header() *RR_Header { return &rr.Hdr }
-func (rr *A) copy() RR           { return &A{*rr.Hdr.copyHeader(), copyIP(rr.A)} }
-func (rr *A) len() int           { return rr.Hdr.len() + net.IPv4len }
+func (rr *A) copy() RR { return &A{*rr.Hdr.copyHeader(), copyIP(rr.A)} }
 
 func (rr *A) String() string {
 	if rr.A == nil {
@@ -773,9 +694,7 @@ type AAAA struct {
 	AAAA net.IP `dns:"aaaa"`
 }
 
-func (rr *AAAA) Header() *RR_Header { return &rr.Hdr }
-func (rr *AAAA) copy() RR           { return &AAAA{*rr.Hdr.copyHeader(), copyIP(rr.AAAA)} }
-func (rr *AAAA) len() int           { return rr.Hdr.len() + net.IPv6len }
+func (rr *AAAA) copy() RR { return &AAAA{*rr.Hdr.copyHeader(), copyIP(rr.AAAA)} }
 
 func (rr *AAAA) String() string {
 	if rr.AAAA == nil {
@@ -791,12 +710,10 @@ type PX struct {
 	Mapx400    string `dns:"domain-name"`
 }
 
-func (rr *PX) Header() *RR_Header { return &rr.Hdr }
-func (rr *PX) copy() RR           { return &PX{*rr.Hdr.copyHeader(), rr.Preference, rr.Map822, rr.Mapx400} }
+func (rr *PX) copy() RR { return &PX{*rr.Hdr.copyHeader(), rr.Preference, rr.Map822, rr.Mapx400} }
 func (rr *PX) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Preference)) + " " + sprintName(rr.Map822) + " " + sprintName(rr.Mapx400)
 }
-func (rr *PX) len() int { return rr.Hdr.len() + 2 + len(rr.Map822) + 1 + len(rr.Mapx400) + 1 }
 
 type GPOS struct {
 	Hdr       RR_Header
@@ -805,11 +722,7 @@ type GPOS struct {
 	Altitude  string
 }
 
-func (rr *GPOS) Header() *RR_Header { return &rr.Hdr }
-func (rr *GPOS) copy() RR           { return &GPOS{*rr.Hdr.copyHeader(), rr.Longitude, rr.Latitude, rr.Altitude} }
-func (rr *GPOS) len() int {
-	return rr.Hdr.len() + len(rr.Longitude) + len(rr.Latitude) + len(rr.Altitude) + 3
-}
+func (rr *GPOS) copy() RR { return &GPOS{*rr.Hdr.copyHeader(), rr.Longitude, rr.Latitude, rr.Altitude} }
 func (rr *GPOS) String() string {
 	return rr.Hdr.String() + rr.Longitude + " " + rr.Latitude + " " + rr.Altitude
 }
@@ -825,8 +738,6 @@ type LOC struct {
 	Altitude  uint32
 }
 
-func (rr *LOC) Header() *RR_Header { return &rr.Hdr }
-func (rr *LOC) len() int           { return rr.Hdr.len() + 4 + 12 }
 func (rr *LOC) copy() RR {
 	return &LOC{*rr.Hdr.copyHeader(), rr.Version, rr.Size, rr.HorizPre, rr.VertPre, rr.Latitude, rr.Longitude, rr.Altitude}
 }
@@ -914,7 +825,6 @@ type RRSIG struct {
 	Signature   string `dns:"base64"`
 }
 
-func (rr *RRSIG) Header() *RR_Header { return &rr.Hdr }
 func (rr *RRSIG) copy() RR {
 	return &RRSIG{*rr.Hdr.copyHeader(), rr.TypeCovered, rr.Algorithm, rr.Labels, rr.OrigTtl, rr.Expiration, rr.Inception, rr.KeyTag, rr.SignerName, rr.Signature}
 }
@@ -933,18 +843,12 @@ func (rr *RRSIG) String() string {
 	return s
 }
 
-func (rr *RRSIG) len() int {
-	return rr.Hdr.len() + len(rr.SignerName) + 1 +
-		base64.StdEncoding.DecodedLen(len(rr.Signature)) + 18
-}
-
 type NSEC struct {
 	Hdr        RR_Header
 	NextDomain string   `dns:"domain-name"`
 	TypeBitMap []uint16 `dns:"nsec"`
 }
 
-func (rr *NSEC) Header() *RR_Header { return &rr.Hdr }
 func (rr *NSEC) copy() RR {
 	cp := make([]uint16, len(rr.TypeBitMap), cap(rr.TypeBitMap))
 	copy(cp, rr.TypeBitMap)
@@ -988,8 +892,6 @@ type DS struct {
 	Digest     string `dns:"hex"`
 }
 
-func (rr *DS) Header() *RR_Header { return &rr.Hdr }
-func (rr *DS) len() int           { return rr.Hdr.len() + 4 + len(rr.Digest)/2 }
 func (rr *DS) copy() RR {
 	return &DS{*rr.Hdr.copyHeader(), rr.KeyTag, rr.Algorithm, rr.DigestType, rr.Digest}
 }
@@ -1007,9 +909,7 @@ type KX struct {
 	Exchanger  string `dns:"domain-name"`
 }
 
-func (rr *KX) Header() *RR_Header { return &rr.Hdr }
-func (rr *KX) len() int           { return rr.Hdr.len() + 2 + len(rr.Exchanger) + 1 }
-func (rr *KX) copy() RR           { return &KX{*rr.Hdr.copyHeader(), rr.Preference, rr.Exchanger} }
+func (rr *KX) copy() RR { return &KX{*rr.Hdr.copyHeader(), rr.Preference, rr.Exchanger} }
 
 func (rr *KX) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Preference)) +
@@ -1024,8 +924,6 @@ type TA struct {
 	Digest     string `dns:"hex"`
 }
 
-func (rr *TA) Header() *RR_Header { return &rr.Hdr }
-func (rr *TA) len() int           { return rr.Hdr.len() + 4 + len(rr.Digest)/2 }
 func (rr *TA) copy() RR {
 	return &TA{*rr.Hdr.copyHeader(), rr.KeyTag, rr.Algorithm, rr.DigestType, rr.Digest}
 }
@@ -1043,9 +941,7 @@ type TALINK struct {
 	NextName     string `dns:"domain-name"`
 }
 
-func (rr *TALINK) Header() *RR_Header { return &rr.Hdr }
-func (rr *TALINK) copy() RR           { return &TALINK{*rr.Hdr.copyHeader(), rr.PreviousName, rr.NextName} }
-func (rr *TALINK) len() int           { return rr.Hdr.len() + len(rr.PreviousName) + len(rr.NextName) + 2 }
+func (rr *TALINK) copy() RR { return &TALINK{*rr.Hdr.copyHeader(), rr.PreviousName, rr.NextName} }
 
 func (rr *TALINK) String() string {
 	return rr.Hdr.String() +
@@ -1059,8 +955,6 @@ type SSHFP struct {
 	FingerPrint string `dns:"hex"`
 }
 
-func (rr *SSHFP) Header() *RR_Header { return &rr.Hdr }
-func (rr *SSHFP) len() int           { return rr.Hdr.len() + 2 + len(rr.FingerPrint)/2 }
 func (rr *SSHFP) copy() RR {
 	return &SSHFP{*rr.Hdr.copyHeader(), rr.Algorithm, rr.Type, rr.FingerPrint}
 }
@@ -1085,7 +979,6 @@ type IPSECKEY struct {
 	PublicKey   string `dns:"base64"`
 }
 
-func (rr *IPSECKEY) Header() *RR_Header { return &rr.Hdr }
 func (rr *IPSECKEY) copy() RR {
 	return &IPSECKEY{*rr.Hdr.copyHeader(), rr.Precedence, rr.GatewayType, rr.Algorithm, rr.GatewayA, rr.GatewayAAAA, rr.GatewayName, rr.PublicKey}
 }
@@ -1143,10 +1036,6 @@ type DNSKEY struct {
 	PublicKey string `dns:"base64"`
 }
 
-func (rr *DNSKEY) Header() *RR_Header { return &rr.Hdr }
-func (rr *DNSKEY) len() int {
-	return rr.Hdr.len() + 4 + base64.StdEncoding.DecodedLen(len(rr.PublicKey))
-}
 func (rr *DNSKEY) copy() RR {
 	return &DNSKEY{*rr.Hdr.copyHeader(), rr.Flags, rr.Protocol, rr.Algorithm, rr.PublicKey}
 }
@@ -1166,8 +1055,6 @@ type RKEY struct {
 	PublicKey string `dns:"base64"`
 }
 
-func (rr *RKEY) Header() *RR_Header { return &rr.Hdr }
-func (rr *RKEY) len() int           { return rr.Hdr.len() + 4 + base64.StdEncoding.DecodedLen(len(rr.PublicKey)) }
 func (rr *RKEY) copy() RR {
 	return &RKEY{*rr.Hdr.copyHeader(), rr.Flags, rr.Protocol, rr.Algorithm, rr.PublicKey}
 }
@@ -1184,10 +1071,8 @@ type NSAPPTR struct {
 	Ptr string `dns:"domain-name"`
 }
 
-func (rr *NSAPPTR) Header() *RR_Header { return &rr.Hdr }
-func (rr *NSAPPTR) copy() RR           { return &NSAPPTR{*rr.Hdr.copyHeader(), rr.Ptr} }
-func (rr *NSAPPTR) String() string     { return rr.Hdr.String() + sprintName(rr.Ptr) }
-func (rr *NSAPPTR) len() int           { return rr.Hdr.len() + len(rr.Ptr) }
+func (rr *NSAPPTR) copy() RR       { return &NSAPPTR{*rr.Hdr.copyHeader(), rr.Ptr} }
+func (rr *NSAPPTR) String() string { return rr.Hdr.String() + sprintName(rr.Ptr) }
 
 type NSEC3 struct {
 	Hdr        RR_Header
@@ -1201,7 +1086,6 @@ type NSEC3 struct {
 	TypeBitMap []uint16 `dns:"nsec"`
 }
 
-func (rr *NSEC3) Header() *RR_Header { return &rr.Hdr }
 func (rr *NSEC3) copy() RR {
 	cp := make([]uint16, len(rr.TypeBitMap), cap(rr.TypeBitMap))
 	copy(cp, rr.TypeBitMap)
@@ -1243,8 +1127,6 @@ type NSEC3PARAM struct {
 	Salt       string `dns:"hex"`
 }
 
-func (rr *NSEC3PARAM) Header() *RR_Header { return &rr.Hdr }
-func (rr *NSEC3PARAM) len() int           { return rr.Hdr.len() + 2 + 4 + 1 + len(rr.Salt)/2 }
 func (rr *NSEC3PARAM) copy() RR {
 	return &NSEC3PARAM{*rr.Hdr.copyHeader(), rr.Hash, rr.Flags, rr.Iterations, rr.SaltLength, rr.Salt}
 }
@@ -1271,7 +1153,6 @@ type TKEY struct {
 	OtherData  string
 }
 
-func (rr *TKEY) Header() *RR_Header { return &rr.Hdr }
 func (rr *TKEY) copy() RR {
 	return &TKEY{*rr.Hdr.copyHeader(), rr.Algorithm, rr.Inception, rr.Expiration, rr.Mode, rr.Error, rr.KeySize, rr.Key, rr.OtherLen, rr.OtherData}
 }
@@ -1281,20 +1162,13 @@ func (rr *TKEY) String() string {
 	return ""
 }
 
-func (rr *TKEY) len() int {
-	return rr.Hdr.len() + len(rr.Algorithm) + 1 + 4 + 4 + 6 +
-		len(rr.Key) + 2 + len(rr.OtherData)
-}
-
 // RFC3597 represents an unknown/generic RR.
 type RFC3597 struct {
 	Hdr   RR_Header
 	Rdata string `dns:"hex"`
 }
 
-func (rr *RFC3597) Header() *RR_Header { return &rr.Hdr }
-func (rr *RFC3597) copy() RR           { return &RFC3597{*rr.Hdr.copyHeader(), rr.Rdata} }
-func (rr *RFC3597) len() int           { return rr.Hdr.len() + len(rr.Rdata)/2 + 2 }
+func (rr *RFC3597) copy() RR { return &RFC3597{*rr.Hdr.copyHeader(), rr.Rdata} }
 
 func (rr *RFC3597) String() string {
 	// Let's call it a hack
@@ -1321,9 +1195,7 @@ type URI struct {
 	Target   string `dns:"octet"`
 }
 
-func (rr *URI) Header() *RR_Header { return &rr.Hdr }
-func (rr *URI) copy() RR           { return &URI{*rr.Hdr.copyHeader(), rr.Weight, rr.Priority, rr.Target} }
-func (rr *URI) len() int           { return rr.Hdr.len() + 4 + len(rr.Target) }
+func (rr *URI) copy() RR { return &URI{*rr.Hdr.copyHeader(), rr.Weight, rr.Priority, rr.Target} }
 func (rr *URI) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Priority)) +
 		" " + strconv.Itoa(int(rr.Weight)) + " " + sprintTxtOctet(rr.Target)
@@ -1334,10 +1206,8 @@ type DHCID struct {
 	Digest string `dns:"base64"`
 }
 
-func (rr *DHCID) Header() *RR_Header { return &rr.Hdr }
-func (rr *DHCID) copy() RR           { return &DHCID{*rr.Hdr.copyHeader(), rr.Digest} }
-func (rr *DHCID) String() string     { return rr.Hdr.String() + rr.Digest }
-func (rr *DHCID) len() int           { return rr.Hdr.len() + base64.StdEncoding.DecodedLen(len(rr.Digest)) }
+func (rr *DHCID) copy() RR       { return &DHCID{*rr.Hdr.copyHeader(), rr.Digest} }
+func (rr *DHCID) String() string { return rr.Hdr.String() + rr.Digest }
 
 type TLSA struct {
 	Hdr          RR_Header
@@ -1347,9 +1217,6 @@ type TLSA struct {
 	Certificate  string `dns:"hex"`
 }
 
-func (rr *TLSA) Header() *RR_Header { return &rr.Hdr }
-func (rr *TLSA) len() int           { return rr.Hdr.len() + 3 + len(rr.Certificate)/2 }
-
 func (rr *TLSA) copy() RR {
 	return &TLSA{*rr.Hdr.copyHeader(), rr.Usage, rr.Selector, rr.MatchingType, rr.Certificate}
 }
@@ -1372,7 +1239,6 @@ type HIP struct {
 	RendezvousServers  []string `dns:"domain-name"`
 }
 
-func (rr *HIP) Header() *RR_Header { return &rr.Hdr }
 func (rr *HIP) copy() RR {
 	cp := make([]string, len(rr.RendezvousServers), cap(rr.RendezvousServers))
 	copy(cp, rr.RendezvousServers)
@@ -1390,22 +1256,11 @@ func (rr *HIP) String() string {
 	return s
 }
 
-func (rr *HIP) len() int {
-	l := rr.Hdr.len() + 4 +
-		len(rr.Hit)/2 +
-		base64.StdEncoding.DecodedLen(len(rr.PublicKey))
-	for _, d := range rr.RendezvousServers {
-		l += len(d) + 1
-	}
-	return l
-}
-
 type NINFO struct {
 	Hdr    RR_Header
 	ZSData []string `dns:"txt"`
 }
 
-func (rr *NINFO) Header() *RR_Header { return &rr.Hdr }
 func (rr *NINFO) copy() RR {
 	cp := make([]string, len(rr.ZSData), cap(rr.ZSData))
 	copy(cp, rr.ZSData)
@@ -1414,14 +1269,6 @@ func (rr *NINFO) copy() RR {
 
 func (rr *NINFO) String() string { return rr.Hdr.String() + sprintTxt(rr.ZSData) }
 
-func (rr *NINFO) len() int {
-	l := rr.Hdr.len()
-	for _, t := range rr.ZSData {
-		l += len(t) + 1
-	}
-	return l
-}
-
 type WKS struct {
 	Hdr      RR_Header
 	Address  net.IP `dns:"a"`
@@ -1429,8 +1276,10 @@ type WKS struct {
 	BitMap   []uint16 `dns:"wks"`
 }
 
-func (rr *WKS) Header() *RR_Header { return &rr.Hdr }
-func (rr *WKS) len() int           { return rr.Hdr.len() + net.IPv4len + 1 }
+func (rr *WKS) len() int {
+	// TODO: this is missing something...
+	return rr.Hdr.len() + net.IPv4len + 1
+}
 
 func (rr *WKS) copy() RR {
 	cp := make([]uint16, len(rr.BitMap), cap(rr.BitMap))
@@ -1457,9 +1306,7 @@ type NID struct {
 	NodeID     uint64
 }
 
-func (rr *NID) Header() *RR_Header { return &rr.Hdr }
-func (rr *NID) copy() RR           { return &NID{*rr.Hdr.copyHeader(), rr.Preference, rr.NodeID} }
-func (rr *NID) len() int           { return rr.Hdr.len() + 2 + 8 }
+func (rr *NID) copy() RR { return &NID{*rr.Hdr.copyHeader(), rr.Preference, rr.NodeID} }
 
 func (rr *NID) String() string {
 	s := rr.Hdr.String() + strconv.Itoa(int(rr.Preference))
@@ -1474,9 +1321,7 @@ type L32 struct {
 	Locator32  net.IP `dns:"a"`
 }
 
-func (rr *L32) Header() *RR_Header { return &rr.Hdr }
-func (rr *L32) copy() RR           { return &L32{*rr.Hdr.copyHeader(), rr.Preference, copyIP(rr.Locator32)} }
-func (rr *L32) len() int           { return rr.Hdr.len() + net.IPv4len }
+func (rr *L32) copy() RR { return &L32{*rr.Hdr.copyHeader(), rr.Preference, copyIP(rr.Locator32)} }
 
 func (rr *L32) String() string {
 	if rr.Locator32 == nil {
@@ -1492,9 +1337,7 @@ type L64 struct {
 	Locator64  uint64
 }
 
-func (rr *L64) Header() *RR_Header { return &rr.Hdr }
-func (rr *L64) copy() RR           { return &L64{*rr.Hdr.copyHeader(), rr.Preference, rr.Locator64} }
-func (rr *L64) len() int           { return rr.Hdr.len() + 2 + 8 }
+func (rr *L64) copy() RR { return &L64{*rr.Hdr.copyHeader(), rr.Preference, rr.Locator64} }
 
 func (rr *L64) String() string {
 	s := rr.Hdr.String() + strconv.Itoa(int(rr.Preference))
@@ -1509,9 +1352,7 @@ type LP struct {
 	Fqdn       string `dns:"domain-name"`
 }
 
-func (rr *LP) Header() *RR_Header { return &rr.Hdr }
-func (rr *LP) copy() RR           { return &LP{*rr.Hdr.copyHeader(), rr.Preference, rr.Fqdn} }
-func (rr *LP) len() int           { return rr.Hdr.len() + 2 + len(rr.Fqdn) + 1 }
+func (rr *LP) copy() RR { return &LP{*rr.Hdr.copyHeader(), rr.Preference, rr.Fqdn} }
 
 func (rr *LP) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Preference)) + " " + sprintName(rr.Fqdn)
@@ -1522,20 +1363,16 @@ type EUI48 struct {
 	Address uint64 `dns:"uint48"`
 }
 
-func (rr *EUI48) Header() *RR_Header { return &rr.Hdr }
-func (rr *EUI48) copy() RR           { return &EUI48{*rr.Hdr.copyHeader(), rr.Address} }
-func (rr *EUI48) String() string     { return rr.Hdr.String() + euiToString(rr.Address, 48) }
-func (rr *EUI48) len() int           { return rr.Hdr.len() + 6 }
+func (rr *EUI48) copy() RR       { return &EUI48{*rr.Hdr.copyHeader(), rr.Address} }
+func (rr *EUI48) String() string { return rr.Hdr.String() + euiToString(rr.Address, 48) }
 
 type EUI64 struct {
 	Hdr     RR_Header
 	Address uint64
 }
 
-func (rr *EUI64) Header() *RR_Header { return &rr.Hdr }
-func (rr *EUI64) copy() RR           { return &EUI64{*rr.Hdr.copyHeader(), rr.Address} }
-func (rr *EUI64) String() string     { return rr.Hdr.String() + euiToString(rr.Address, 64) }
-func (rr *EUI64) len() int           { return rr.Hdr.len() + 8 }
+func (rr *EUI64) copy() RR       { return &EUI64{*rr.Hdr.copyHeader(), rr.Address} }
+func (rr *EUI64) String() string { return rr.Hdr.String() + euiToString(rr.Address, 64) }
 
 type CAA struct {
 	Hdr   RR_Header
@@ -1544,9 +1381,7 @@ type CAA struct {
 	Value string `dns:"octet"`
 }
 
-func (rr *CAA) Header() *RR_Header { return &rr.Hdr }
-func (rr *CAA) copy() RR           { return &CAA{*rr.Hdr.copyHeader(), rr.Flag, rr.Tag, rr.Value} }
-func (rr *CAA) len() int           { return rr.Hdr.len() + 2 + len(rr.Tag) + len(rr.Value) }
+func (rr *CAA) copy() RR { return &CAA{*rr.Hdr.copyHeader(), rr.Flag, rr.Tag, rr.Value} }
 func (rr *CAA) String() string {
 	return rr.Hdr.String() + strconv.Itoa(int(rr.Flag)) + " " + rr.Tag + " " + sprintTxtOctet(rr.Value)
 }
@@ -1556,62 +1391,48 @@ type UID struct {
 	Uid uint32
 }
 
-func (rr *UID) Header() *RR_Header { return &rr.Hdr }
-func (rr *UID) copy() RR           { return &UID{*rr.Hdr.copyHeader(), rr.Uid} }
-func (rr *UID) String() string     { return rr.Hdr.String() + strconv.FormatInt(int64(rr.Uid), 10) }
-func (rr *UID) len() int           { return rr.Hdr.len() + 4 }
+func (rr *UID) copy() RR       { return &UID{*rr.Hdr.copyHeader(), rr.Uid} }
+func (rr *UID) String() string { return rr.Hdr.String() + strconv.FormatInt(int64(rr.Uid), 10) }
 
 type GID struct {
 	Hdr RR_Header
 	Gid uint32
 }
 
-func (rr *GID) Header() *RR_Header { return &rr.Hdr }
-func (rr *GID) copy() RR           { return &GID{*rr.Hdr.copyHeader(), rr.Gid} }
-func (rr *GID) String() string     { return rr.Hdr.String() + strconv.FormatInt(int64(rr.Gid), 10) }
-func (rr *GID) len() int           { return rr.Hdr.len() + 4 }
+func (rr *GID) copy() RR       { return &GID{*rr.Hdr.copyHeader(), rr.Gid} }
+func (rr *GID) String() string { return rr.Hdr.String() + strconv.FormatInt(int64(rr.Gid), 10) }
 
 type UINFO struct {
 	Hdr   RR_Header
 	Uinfo string
 }
 
-func (rr *UINFO) Header() *RR_Header { return &rr.Hdr }
-func (rr *UINFO) copy() RR           { return &UINFO{*rr.Hdr.copyHeader(), rr.Uinfo} }
-func (rr *UINFO) String() string     { return rr.Hdr.String() + sprintTxt([]string{rr.Uinfo}) }
-func (rr *UINFO) len() int           { return rr.Hdr.len() + len(rr.Uinfo) + 1 }
+func (rr *UINFO) copy() RR       { return &UINFO{*rr.Hdr.copyHeader(), rr.Uinfo} }
+func (rr *UINFO) String() string { return rr.Hdr.String() + sprintTxt([]string{rr.Uinfo}) }
 
 type EID struct {
 	Hdr      RR_Header
 	Endpoint string `dns:"hex"`
 }
 
-func (rr *EID) Header() *RR_Header { return &rr.Hdr }
-func (rr *EID) copy() RR           { return &EID{*rr.Hdr.copyHeader(), rr.Endpoint} }
-func (rr *EID) String() string     { return rr.Hdr.String() + strings.ToUpper(rr.Endpoint) }
-func (rr *EID) len() int           { return rr.Hdr.len() + len(rr.Endpoint)/2 }
+func (rr *EID) copy() RR       { return &EID{*rr.Hdr.copyHeader(), rr.Endpoint} }
+func (rr *EID) String() string { return rr.Hdr.String() + strings.ToUpper(rr.Endpoint) }
 
 type NIMLOC struct {
 	Hdr     RR_Header
 	Locator string `dns:"hex"`
 }
 
-func (rr *NIMLOC) Header() *RR_Header { return &rr.Hdr }
-func (rr *NIMLOC) copy() RR           { return &NIMLOC{*rr.Hdr.copyHeader(), rr.Locator} }
-func (rr *NIMLOC) String() string     { return rr.Hdr.String() + strings.ToUpper(rr.Locator) }
-func (rr *NIMLOC) len() int           { return rr.Hdr.len() + len(rr.Locator)/2 }
+func (rr *NIMLOC) copy() RR       { return &NIMLOC{*rr.Hdr.copyHeader(), rr.Locator} }
+func (rr *NIMLOC) String() string { return rr.Hdr.String() + strings.ToUpper(rr.Locator) }
 
 type OPENPGPKEY struct {
 	Hdr       RR_Header
 	PublicKey string `dns:"base64"`
 }
 
-func (rr *OPENPGPKEY) Header() *RR_Header { return &rr.Hdr }
-func (rr *OPENPGPKEY) copy() RR           { return &OPENPGPKEY{*rr.Hdr.copyHeader(), rr.PublicKey} }
-func (rr *OPENPGPKEY) String() string     { return rr.Hdr.String() + rr.PublicKey }
-func (rr *OPENPGPKEY) len() int {
-	return rr.Hdr.len() + base64.StdEncoding.DecodedLen(len(rr.PublicKey))
-}
+func (rr *OPENPGPKEY) copy() RR       { return &OPENPGPKEY{*rr.Hdr.copyHeader(), rr.PublicKey} }
+func (rr *OPENPGPKEY) String() string { return rr.Hdr.String() + rr.PublicKey }
 
 // TimeToString translates the RRSIG's incep. and expir. times to the
 // string representation used when printing the record.
@@ -1669,73 +1490,3 @@ func copyIP(ip net.IP) net.IP {
 	copy(p, ip)
 	return p
 }
-
-// Map of constructors for each RR type.
-var typeToRR = map[uint16]func() RR{
-	TypeA:          func() RR { return new(A) },
-	TypeAAAA:       func() RR { return new(AAAA) },
-	TypeAFSDB:      func() RR { return new(AFSDB) },
-	TypeCAA:        func() RR { return new(CAA) },
-	TypeCDS:        func() RR { return new(CDS) },
-	TypeCERT:       func() RR { return new(CERT) },
-	TypeCNAME:      func() RR { return new(CNAME) },
-	TypeDHCID:      func() RR { return new(DHCID) },
-	TypeDLV:        func() RR { return new(DLV) },
-	TypeDNAME:      func() RR { return new(DNAME) },
-	TypeKEY:        func() RR { return new(KEY) },
-	TypeDNSKEY:     func() RR { return new(DNSKEY) },
-	TypeDS:         func() RR { return new(DS) },
-	TypeEUI48:      func() RR { return new(EUI48) },
-	TypeEUI64:      func() RR { return new(EUI64) },
-	TypeGID:        func() RR { return new(GID) },
-	TypeGPOS:       func() RR { return new(GPOS) },
-	TypeEID:        func() RR { return new(EID) },
-	TypeHINFO:      func() RR { return new(HINFO) },
-	TypeHIP:        func() RR { return new(HIP) },
-	TypeIPSECKEY:   func() RR { return new(IPSECKEY) },
-	TypeKX:         func() RR { return new(KX) },
-	TypeL32:        func() RR { return new(L32) },
-	TypeL64:        func() RR { return new(L64) },
-	TypeLOC:        func() RR { return new(LOC) },
-	TypeLP:         func() RR { return new(LP) },
-	TypeMB:         func() RR { return new(MB) },
-	TypeMD:         func() RR { return new(MD) },
-	TypeMF:         func() RR { return new(MF) },
-	TypeMG:         func() RR { return new(MG) },
-	TypeMINFO:      func() RR { return new(MINFO) },
-	TypeMR:         func() RR { return new(MR) },
-	TypeMX:         func() RR { return new(MX) },
-	TypeNAPTR:      func() RR { return new(NAPTR) },
-	TypeNID:        func() RR { return new(NID) },
-	TypeNINFO:      func() RR { return new(NINFO) },
-	TypeNIMLOC:     func() RR { return new(NIMLOC) },
-	TypeNS:         func() RR { return new(NS) },
-	TypeNSAPPTR:    func() RR { return new(NSAPPTR) },
-	TypeNSEC3:      func() RR { return new(NSEC3) },
-	TypeNSEC3PARAM: func() RR { return new(NSEC3PARAM) },
-	TypeNSEC:       func() RR { return new(NSEC) },
-	TypeOPENPGPKEY: func() RR { return new(OPENPGPKEY) },
-	TypeOPT:        func() RR { return new(OPT) },
-	TypePTR:        func() RR { return new(PTR) },
-	TypeRKEY:       func() RR { return new(RKEY) },
-	TypeRP:         func() RR { return new(RP) },
-	TypePX:         func() RR { return new(PX) },
-	TypeSIG:        func() RR { return new(SIG) },
-	TypeRRSIG:      func() RR { return new(RRSIG) },
-	TypeRT:         func() RR { return new(RT) },
-	TypeSOA:        func() RR { return new(SOA) },
-	TypeSPF:        func() RR { return new(SPF) },
-	TypeSRV:        func() RR { return new(SRV) },
-	TypeSSHFP:      func() RR { return new(SSHFP) },
-	TypeTA:         func() RR { return new(TA) },
-	TypeTALINK:     func() RR { return new(TALINK) },
-	TypeTKEY:       func() RR { return new(TKEY) },
-	TypeTLSA:       func() RR { return new(TLSA) },
-	TypeTSIG:       func() RR { return new(TSIG) },
-	TypeTXT:        func() RR { return new(TXT) },
-	TypeUID:        func() RR { return new(UID) },
-	TypeUINFO:      func() RR { return new(UINFO) },
-	TypeURI:        func() RR { return new(URI) },
-	TypeWKS:        func() RR { return new(WKS) },
-	TypeX25:        func() RR { return new(X25) },
-}
diff --git a/types_auto.go b/types_auto.go
new file mode 100644
index 00000000..4379f7bd
--- /dev/null
+++ b/types_auto.go
@@ -0,0 +1,632 @@
+// *** DO NOT MODIFY ***
+// AUTOGENERATED BY go generate
+
+package dns
+
+import (
+	"encoding/base64"
+	"net"
+)
+
+// Map of constructors for each RR type.
+var typeToRR = map[uint16]func() RR{
+	TypeA:          func() RR { return new(A) },
+	TypeAAAA:       func() RR { return new(AAAA) },
+	TypeAFSDB:      func() RR { return new(AFSDB) },
+	TypeANY:        func() RR { return new(ANY) },
+	TypeCAA:        func() RR { return new(CAA) },
+	TypeCDNSKEY:    func() RR { return new(CDNSKEY) },
+	TypeCDS:        func() RR { return new(CDS) },
+	TypeCERT:       func() RR { return new(CERT) },
+	TypeCNAME:      func() RR { return new(CNAME) },
+	TypeDHCID:      func() RR { return new(DHCID) },
+	TypeDLV:        func() RR { return new(DLV) },
+	TypeDNAME:      func() RR { return new(DNAME) },
+	TypeDNSKEY:     func() RR { return new(DNSKEY) },
+	TypeDS:         func() RR { return new(DS) },
+	TypeEID:        func() RR { return new(EID) },
+	TypeEUI48:      func() RR { return new(EUI48) },
+	TypeEUI64:      func() RR { return new(EUI64) },
+	TypeGID:        func() RR { return new(GID) },
+	TypeGPOS:       func() RR { return new(GPOS) },
+	TypeHINFO:      func() RR { return new(HINFO) },
+	TypeHIP:        func() RR { return new(HIP) },
+	TypeIPSECKEY:   func() RR { return new(IPSECKEY) },
+	TypeKEY:        func() RR { return new(KEY) },
+	TypeKX:         func() RR { return new(KX) },
+	TypeL32:        func() RR { return new(L32) },
+	TypeL64:        func() RR { return new(L64) },
+	TypeLOC:        func() RR { return new(LOC) },
+	TypeLP:         func() RR { return new(LP) },
+	TypeMB:         func() RR { return new(MB) },
+	TypeMD:         func() RR { return new(MD) },
+	TypeMF:         func() RR { return new(MF) },
+	TypeMG:         func() RR { return new(MG) },
+	TypeMINFO:      func() RR { return new(MINFO) },
+	TypeMR:         func() RR { return new(MR) },
+	TypeMX:         func() RR { return new(MX) },
+	TypeNAPTR:      func() RR { return new(NAPTR) },
+	TypeNID:        func() RR { return new(NID) },
+	TypeNIMLOC:     func() RR { return new(NIMLOC) },
+	TypeNINFO:      func() RR { return new(NINFO) },
+	TypeNS:         func() RR { return new(NS) },
+	TypeNSAPPTR:    func() RR { return new(NSAPPTR) },
+	TypeNSEC:       func() RR { return new(NSEC) },
+	TypeNSEC3:      func() RR { return new(NSEC3) },
+	TypeNSEC3PARAM: func() RR { return new(NSEC3PARAM) },
+	TypeOPENPGPKEY: func() RR { return new(OPENPGPKEY) },
+	TypeOPT:        func() RR { return new(OPT) },
+	TypePTR:        func() RR { return new(PTR) },
+	TypePX:         func() RR { return new(PX) },
+	TypeRKEY:       func() RR { return new(RKEY) },
+	TypeRP:         func() RR { return new(RP) },
+	TypeRRSIG:      func() RR { return new(RRSIG) },
+	TypeRT:         func() RR { return new(RT) },
+	TypeSIG:        func() RR { return new(SIG) },
+	TypeSOA:        func() RR { return new(SOA) },
+	TypeSPF:        func() RR { return new(SPF) },
+	TypeSRV:        func() RR { return new(SRV) },
+	TypeSSHFP:      func() RR { return new(SSHFP) },
+	TypeTA:         func() RR { return new(TA) },
+	TypeTALINK:     func() RR { return new(TALINK) },
+	TypeTKEY:       func() RR { return new(TKEY) },
+	TypeTLSA:       func() RR { return new(TLSA) },
+	TypeTSIG:       func() RR { return new(TSIG) },
+	TypeTXT:        func() RR { return new(TXT) },
+	TypeUID:        func() RR { return new(UID) },
+	TypeUINFO:      func() RR { return new(UINFO) },
+	TypeURI:        func() RR { return new(URI) },
+	TypeWKS:        func() RR { return new(WKS) },
+	TypeX25:        func() RR { return new(X25) },
+}
+
+// TypeToString is a map of strings for each RR wire type.
+var TypeToString = map[uint16]string{
+	TypeA:          "A",
+	TypeAAAA:       "AAAA",
+	TypeAFSDB:      "AFSDB",
+	TypeANY:        "ANY",
+	TypeATMA:       "ATMA",
+	TypeAXFR:       "AXFR",
+	TypeCAA:        "CAA",
+	TypeCDNSKEY:    "CDNSKEY",
+	TypeCDS:        "CDS",
+	TypeCERT:       "CERT",
+	TypeCNAME:      "CNAME",
+	TypeDHCID:      "DHCID",
+	TypeDLV:        "DLV",
+	TypeDNAME:      "DNAME",
+	TypeDNSKEY:     "DNSKEY",
+	TypeDS:         "DS",
+	TypeEID:        "EID",
+	TypeEUI48:      "EUI48",
+	TypeEUI64:      "EUI64",
+	TypeGID:        "GID",
+	TypeGPOS:       "GPOS",
+	TypeHINFO:      "HINFO",
+	TypeHIP:        "HIP",
+	TypeIPSECKEY:   "IPSECKEY",
+	TypeISDN:       "ISDN",
+	TypeIXFR:       "IXFR",
+	TypeKEY:        "KEY",
+	TypeKX:         "KX",
+	TypeL32:        "L32",
+	TypeL64:        "L64",
+	TypeLOC:        "LOC",
+	TypeLP:         "LP",
+	TypeMAILA:      "MAILA",
+	TypeMAILB:      "MAILB",
+	TypeMB:         "MB",
+	TypeMD:         "MD",
+	TypeMF:         "MF",
+	TypeMG:         "MG",
+	TypeMINFO:      "MINFO",
+	TypeMR:         "MR",
+	TypeMX:         "MX",
+	TypeNAPTR:      "NAPTR",
+	TypeNID:        "NID",
+	TypeNIMLOC:     "NIMLOC",
+	TypeNINFO:      "NINFO",
+	TypeNS:         "NS",
+	TypeNSEC:       "NSEC",
+	TypeNSEC3:      "NSEC3",
+	TypeNSEC3PARAM: "NSEC3PARAM",
+	TypeNULL:       "NULL",
+	TypeNXT:        "NXT",
+	TypeNone:       "None",
+	TypeOPENPGPKEY: "OPENPGPKEY",
+	TypeOPT:        "OPT",
+	TypePTR:        "PTR",
+	TypePX:         "PX",
+	TypeRKEY:       "RKEY",
+	TypeRP:         "RP",
+	TypeRRSIG:      "RRSIG",
+	TypeRT:         "RT",
+	TypeReserved:   "Reserved",
+	TypeSIG:        "SIG",
+	TypeSOA:        "SOA",
+	TypeSPF:        "SPF",
+	TypeSRV:        "SRV",
+	TypeSSHFP:      "SSHFP",
+	TypeTA:         "TA",
+	TypeTALINK:     "TALINK",
+	TypeTKEY:       "TKEY",
+	TypeTLSA:       "TLSA",
+	TypeTSIG:       "TSIG",
+	TypeTXT:        "TXT",
+	TypeUID:        "UID",
+	TypeUINFO:      "UINFO",
+	TypeUNSPEC:     "UNSPEC",
+	TypeURI:        "URI",
+	TypeWKS:        "WKS",
+	TypeX25:        "X25",
+	TypeNSAPPTR:    "NSAP-PTR",
+}
+
+// Header() functions
+func (rr *A) Header() *RR_Header          { return &rr.Hdr }
+func (rr *AAAA) Header() *RR_Header       { return &rr.Hdr }
+func (rr *AFSDB) Header() *RR_Header      { return &rr.Hdr }
+func (rr *ANY) Header() *RR_Header        { return &rr.Hdr }
+func (rr *CAA) Header() *RR_Header        { return &rr.Hdr }
+func (rr *CDNSKEY) Header() *RR_Header    { return &rr.Hdr }
+func (rr *CDS) Header() *RR_Header        { return &rr.Hdr }
+func (rr *CERT) Header() *RR_Header       { return &rr.Hdr }
+func (rr *CNAME) Header() *RR_Header      { return &rr.Hdr }
+func (rr *DHCID) Header() *RR_Header      { return &rr.Hdr }
+func (rr *DLV) Header() *RR_Header        { return &rr.Hdr }
+func (rr *DNAME) Header() *RR_Header      { return &rr.Hdr }
+func (rr *DNSKEY) Header() *RR_Header     { return &rr.Hdr }
+func (rr *DS) Header() *RR_Header         { return &rr.Hdr }
+func (rr *EID) Header() *RR_Header        { return &rr.Hdr }
+func (rr *EUI48) Header() *RR_Header      { return &rr.Hdr }
+func (rr *EUI64) Header() *RR_Header      { return &rr.Hdr }
+func (rr *GID) Header() *RR_Header        { return &rr.Hdr }
+func (rr *GPOS) Header() *RR_Header       { return &rr.Hdr }
+func (rr *HINFO) Header() *RR_Header      { return &rr.Hdr }
+func (rr *HIP) Header() *RR_Header        { return &rr.Hdr }
+func (rr *IPSECKEY) Header() *RR_Header   { return &rr.Hdr }
+func (rr *KEY) Header() *RR_Header        { return &rr.Hdr }
+func (rr *KX) Header() *RR_Header         { return &rr.Hdr }
+func (rr *L32) Header() *RR_Header        { return &rr.Hdr }
+func (rr *L64) Header() *RR_Header        { return &rr.Hdr }
+func (rr *LOC) Header() *RR_Header        { return &rr.Hdr }
+func (rr *LP) Header() *RR_Header         { return &rr.Hdr }
+func (rr *MB) Header() *RR_Header         { return &rr.Hdr }
+func (rr *MD) Header() *RR_Header         { return &rr.Hdr }
+func (rr *MF) Header() *RR_Header         { return &rr.Hdr }
+func (rr *MG) Header() *RR_Header         { return &rr.Hdr }
+func (rr *MINFO) Header() *RR_Header      { return &rr.Hdr }
+func (rr *MR) Header() *RR_Header         { return &rr.Hdr }
+func (rr *MX) Header() *RR_Header         { return &rr.Hdr }
+func (rr *NAPTR) Header() *RR_Header      { return &rr.Hdr }
+func (rr *NID) Header() *RR_Header        { return &rr.Hdr }
+func (rr *NIMLOC) Header() *RR_Header     { return &rr.Hdr }
+func (rr *NINFO) Header() *RR_Header      { return &rr.Hdr }
+func (rr *NS) Header() *RR_Header         { return &rr.Hdr }
+func (rr *NSAPPTR) Header() *RR_Header    { return &rr.Hdr }
+func (rr *NSEC) Header() *RR_Header       { return &rr.Hdr }
+func (rr *NSEC3) Header() *RR_Header      { return &rr.Hdr }
+func (rr *NSEC3PARAM) Header() *RR_Header { return &rr.Hdr }
+func (rr *OPENPGPKEY) Header() *RR_Header { return &rr.Hdr }
+func (rr *OPT) Header() *RR_Header        { return &rr.Hdr }
+func (rr *PTR) Header() *RR_Header        { return &rr.Hdr }
+func (rr *PX) Header() *RR_Header         { return &rr.Hdr }
+func (rr *RFC3597) Header() *RR_Header    { return &rr.Hdr }
+func (rr *RKEY) Header() *RR_Header       { return &rr.Hdr }
+func (rr *RP) Header() *RR_Header         { return &rr.Hdr }
+func (rr *RRSIG) Header() *RR_Header      { return &rr.Hdr }
+func (rr *RT) Header() *RR_Header         { return &rr.Hdr }
+func (rr *SIG) Header() *RR_Header        { return &rr.Hdr }
+func (rr *SOA) Header() *RR_Header        { return &rr.Hdr }
+func (rr *SPF) Header() *RR_Header        { return &rr.Hdr }
+func (rr *SRV) Header() *RR_Header        { return &rr.Hdr }
+func (rr *SSHFP) Header() *RR_Header      { return &rr.Hdr }
+func (rr *TA) Header() *RR_Header         { return &rr.Hdr }
+func (rr *TALINK) Header() *RR_Header     { return &rr.Hdr }
+func (rr *TKEY) Header() *RR_Header       { return &rr.Hdr }
+func (rr *TLSA) Header() *RR_Header       { return &rr.Hdr }
+func (rr *TSIG) Header() *RR_Header       { return &rr.Hdr }
+func (rr *TXT) Header() *RR_Header        { return &rr.Hdr }
+func (rr *UID) Header() *RR_Header        { return &rr.Hdr }
+func (rr *UINFO) Header() *RR_Header      { return &rr.Hdr }
+func (rr *URI) Header() *RR_Header        { return &rr.Hdr }
+func (rr *WKS) Header() *RR_Header        { return &rr.Hdr }
+func (rr *X25) Header() *RR_Header        { return &rr.Hdr }
+
+// len() functions
+func (rr *A) len() int {
+	l := rr.Hdr.len()
+	l += net.IPv4len // A
+	return l
+}
+func (rr *AAAA) len() int {
+	l := rr.Hdr.len()
+	l += net.IPv6len // AAAA
+	return l
+}
+func (rr *AFSDB) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Subtype
+	l += len(rr.Hostname) + 1
+	return l
+}
+func (rr *ANY) len() int {
+	l := rr.Hdr.len()
+	return l
+}
+func (rr *CAA) len() int {
+	l := rr.Hdr.len()
+	l += 1 // Flag
+	l += len(rr.Tag) + 1
+	l += len(rr.Value)
+	return l
+}
+func (rr *CERT) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Type
+	l += 2 // KeyTag
+	l += 1 // Algorithm
+	l += base64.StdEncoding.DecodedLen(len(rr.Certificate))
+	return l
+}
+func (rr *CNAME) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Target) + 1
+	return l
+}
+func (rr *DHCID) len() int {
+	l := rr.Hdr.len()
+	l += base64.StdEncoding.DecodedLen(len(rr.Digest))
+	return l
+}
+func (rr *DNAME) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Target) + 1
+	return l
+}
+func (rr *DNSKEY) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Flags
+	l += 1 // Protocol
+	l += 1 // Algorithm
+	l += base64.StdEncoding.DecodedLen(len(rr.PublicKey))
+	return l
+}
+func (rr *DS) len() int {
+	l := rr.Hdr.len()
+	l += 2 // KeyTag
+	l += 1 // Algorithm
+	l += 1 // DigestType
+	l += len(rr.Digest)/2 + 1
+	return l
+}
+func (rr *EID) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Endpoint)/2 + 1
+	return l
+}
+func (rr *EUI48) len() int {
+	l := rr.Hdr.len()
+	l += 6 // Address
+	return l
+}
+func (rr *EUI64) len() int {
+	l := rr.Hdr.len()
+	l += 8 // Address
+	return l
+}
+func (rr *GID) len() int {
+	l := rr.Hdr.len()
+	l += 4 // Gid
+	return l
+}
+func (rr *GPOS) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Longitude) + 1
+	l += len(rr.Latitude) + 1
+	l += len(rr.Altitude) + 1
+	return l
+}
+func (rr *HINFO) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Cpu) + 1
+	l += len(rr.Os) + 1
+	return l
+}
+func (rr *HIP) len() int {
+	l := rr.Hdr.len()
+	l += 1 // HitLength
+	l += 1 // PublicKeyAlgorithm
+	l += 2 // PublicKeyLength
+	l += len(rr.Hit)/2 + 1
+	l += base64.StdEncoding.DecodedLen(len(rr.PublicKey))
+	for _, x := range rr.RendezvousServers {
+		l += len(x) + 1
+	}
+	return l
+}
+func (rr *KX) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += len(rr.Exchanger) + 1
+	return l
+}
+func (rr *L32) len() int {
+	l := rr.Hdr.len()
+	l += 2           // Preference
+	l += net.IPv4len // Locator32
+	return l
+}
+func (rr *L64) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += 8 // Locator64
+	return l
+}
+func (rr *LOC) len() int {
+	l := rr.Hdr.len()
+	l += 1 // Version
+	l += 1 // Size
+	l += 1 // HorizPre
+	l += 1 // VertPre
+	l += 4 // Latitude
+	l += 4 // Longitude
+	l += 4 // Altitude
+	return l
+}
+func (rr *LP) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += len(rr.Fqdn) + 1
+	return l
+}
+func (rr *MB) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Mb) + 1
+	return l
+}
+func (rr *MD) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Md) + 1
+	return l
+}
+func (rr *MF) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Mf) + 1
+	return l
+}
+func (rr *MG) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Mg) + 1
+	return l
+}
+func (rr *MINFO) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Rmail) + 1
+	l += len(rr.Email) + 1
+	return l
+}
+func (rr *MR) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Mr) + 1
+	return l
+}
+func (rr *MX) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += len(rr.Mx) + 1
+	return l
+}
+func (rr *NAPTR) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Order
+	l += 2 // Preference
+	l += len(rr.Flags) + 1
+	l += len(rr.Service) + 1
+	l += len(rr.Regexp) + 1
+	l += len(rr.Replacement) + 1
+	return l
+}
+func (rr *NID) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += 8 // NodeID
+	return l
+}
+func (rr *NIMLOC) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Locator)/2 + 1
+	return l
+}
+func (rr *NINFO) len() int {
+	l := rr.Hdr.len()
+	for _, x := range rr.ZSData {
+		l += len(x) + 1
+	}
+	return l
+}
+func (rr *NS) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Ns) + 1
+	return l
+}
+func (rr *NSAPPTR) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Ptr) + 1
+	return l
+}
+func (rr *NSEC3PARAM) len() int {
+	l := rr.Hdr.len()
+	l += 1 // Hash
+	l += 1 // Flags
+	l += 2 // Iterations
+	l += 1 // SaltLength
+	l += len(rr.Salt)/2 + 1
+	return l
+}
+func (rr *OPENPGPKEY) len() int {
+	l := rr.Hdr.len()
+	l += base64.StdEncoding.DecodedLen(len(rr.PublicKey))
+	return l
+}
+func (rr *PTR) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Ptr) + 1
+	return l
+}
+func (rr *PX) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += len(rr.Map822) + 1
+	l += len(rr.Mapx400) + 1
+	return l
+}
+func (rr *RFC3597) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Rdata)/2 + 1
+	return l
+}
+func (rr *RKEY) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Flags
+	l += 1 // Protocol
+	l += 1 // Algorithm
+	l += base64.StdEncoding.DecodedLen(len(rr.PublicKey))
+	return l
+}
+func (rr *RP) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Mbox) + 1
+	l += len(rr.Txt) + 1
+	return l
+}
+func (rr *RRSIG) len() int {
+	l := rr.Hdr.len()
+	l += 2 // TypeCovered
+	l += 1 // Algorithm
+	l += 1 // Labels
+	l += 4 // OrigTtl
+	l += 4 // Expiration
+	l += 4 // Inception
+	l += 2 // KeyTag
+	l += len(rr.SignerName) + 1
+	l += base64.StdEncoding.DecodedLen(len(rr.Signature))
+	return l
+}
+func (rr *RT) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Preference
+	l += len(rr.Host) + 1
+	return l
+}
+func (rr *SOA) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Ns) + 1
+	l += len(rr.Mbox) + 1
+	l += 4 // Serial
+	l += 4 // Refresh
+	l += 4 // Retry
+	l += 4 // Expire
+	l += 4 // Minttl
+	return l
+}
+func (rr *SPF) len() int {
+	l := rr.Hdr.len()
+	for _, x := range rr.Txt {
+		l += len(x) + 1
+	}
+	return l
+}
+func (rr *SRV) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Priority
+	l += 2 // Weight
+	l += 2 // Port
+	l += len(rr.Target) + 1
+	return l
+}
+func (rr *SSHFP) len() int {
+	l := rr.Hdr.len()
+	l += 1 // Algorithm
+	l += 1 // Type
+	l += len(rr.FingerPrint)/2 + 1
+	return l
+}
+func (rr *TA) len() int {
+	l := rr.Hdr.len()
+	l += 2 // KeyTag
+	l += 1 // Algorithm
+	l += 1 // DigestType
+	l += len(rr.Digest)/2 + 1
+	return l
+}
+func (rr *TALINK) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.PreviousName) + 1
+	l += len(rr.NextName) + 1
+	return l
+}
+func (rr *TKEY) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Algorithm) + 1
+	l += 4 // Inception
+	l += 4 // Expiration
+	l += 2 // Mode
+	l += 2 // Error
+	l += 2 // KeySize
+	l += len(rr.Key) + 1
+	l += 2 // OtherLen
+	l += len(rr.OtherData) + 1
+	return l
+}
+func (rr *TLSA) len() int {
+	l := rr.Hdr.len()
+	l += 1 // Usage
+	l += 1 // Selector
+	l += 1 // MatchingType
+	l += len(rr.Certificate)/2 + 1
+	return l
+}
+func (rr *TSIG) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Algorithm) + 1
+	l += 6 // TimeSigned
+	l += 2 // Fudge
+	l += 2 // MACSize
+	l += len(rr.MAC)/2 + 1
+	l += 2 // OrigId
+	l += 2 // Error
+	l += 2 // OtherLen
+	l += len(rr.OtherData)/2 + 1
+	return l
+}
+func (rr *TXT) len() int {
+	l := rr.Hdr.len()
+	for _, x := range rr.Txt {
+		l += len(x) + 1
+	}
+	return l
+}
+func (rr *UID) len() int {
+	l := rr.Hdr.len()
+	l += 4 // Uid
+	return l
+}
+func (rr *UINFO) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.Uinfo) + 1
+	return l
+}
+func (rr *URI) len() int {
+	l := rr.Hdr.len()
+	l += 2 // Priority
+	l += 2 // Weight
+	l += len(rr.Target)
+	return l
+}
+func (rr *X25) len() int {
+	l := rr.Hdr.len()
+	l += len(rr.PSDNAddress) + 1
+	return l
+}
diff --git a/types_generate.go b/types_generate.go
new file mode 100644
index 00000000..2d27b5e8
--- /dev/null
+++ b/types_generate.go
@@ -0,0 +1,226 @@
+//+build ignore
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"log"
+	"os"
+	"strings"
+	"text/template"
+
+	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/types"
+)
+
+var skip = map[string]struct{}{
+	"PrivateRR": struct{}{},
+}
+
+var skipLen = map[string]struct{}{
+	"NSEC":     struct{}{},
+	"NSEC3":    struct{}{},
+	"OPT":      struct{}{},
+	"WKS":      struct{}{},
+	"IPSECKEY": struct{}{},
+}
+
+var packageHdr = `
+// *** DO NOT MODIFY ***
+// AUTOGENERATED BY go generate
+
+package dns
+
+import (
+	"encoding/base64"
+	"net"
+)
+
+`
+
+var typeToRR = template.Must(template.New("typeToRR").Parse(`
+// Map of constructors for each RR type.
+var typeToRR = map[uint16]func() RR{
+{{range .}}{{if ne . "RFC3597"}}  Type{{.}}:  func() RR { return new({{.}}) },
+{{end}}{{end}}                    }
+
+`))
+
+var typeToString = template.Must(template.New("typeToString").Parse(`
+// TypeToString is a map of strings for each RR wire type.
+var TypeToString = map[uint16]string{
+{{range .}}{{if ne . "NSAPPTR"}}  Type{{.}}: "{{.}}",
+{{end}}{{end}}                    TypeNSAPPTR:    "NSAP-PTR",
+}
+
+`))
+
+var headerFunc = template.Must(template.New("headerFunc").Parse(`
+// Header() functions
+{{range .}}  func (rr *{{.}}) Header() *RR_Header { return &rr.Hdr }
+{{end}}
+
+`))
+
+func getTypeStruct(t types.Type, scope *types.Scope) (*types.Struct, bool) {
+	st, ok := t.Underlying().(*types.Struct)
+	if !ok {
+		return nil, false
+	}
+	if st.Field(0).Type() == scope.Lookup("RR_Header").Type() {
+		return st, false
+	}
+	if st.Field(0).Anonymous() {
+		st, _ := getTypeStruct(st.Field(0).Type(), scope)
+		return st, true
+	}
+	return nil, false
+}
+
+func main() {
+	var conf loader.Config
+	conf.Import(".")
+	prog, err := conf.Load()
+	fatalIfErr(err)
+	scope := prog.Package(".").Pkg.Scope()
+
+	// Collect constants like TypeX
+	var numberedTypes []string
+	for _, name := range scope.Names() {
+		o := scope.Lookup(name)
+		if o == nil || !o.Exported() {
+			continue
+		}
+		b, ok := o.Type().(*types.Basic)
+		if !ok || b.Kind() != types.Uint16 {
+			continue
+		}
+		if !strings.HasPrefix(o.Name(), "Type") {
+			continue
+		}
+		name := strings.TrimPrefix(o.Name(), "Type")
+		if _, ok := skip[name]; ok {
+			continue
+		}
+		numberedTypes = append(numberedTypes, name)
+	}
+
+	// Collect actual types (*X)
+	var namedTypes []string
+	for _, name := range scope.Names() {
+		o := scope.Lookup(name)
+		if o == nil || !o.Exported() {
+			continue
+		}
+		if st, _ := getTypeStruct(o.Type(), scope); st == nil {
+			continue
+		}
+		if _, ok := skip[o.Name()]; ok {
+			continue
+		}
+
+		// Check if corresponding TypeX exists
+		if scope.Lookup("Type"+o.Name()) == nil && o.Name() != "RFC3597" {
+			log.Fatalf("Constant Type%s does not exist.", o.Name())
+		}
+
+		namedTypes = append(namedTypes, o.Name())
+	}
+
+	b := &bytes.Buffer{}
+	b.WriteString(packageHdr)
+
+	// Generate typeToRR
+	fatalIfErr(typeToRR.Execute(b, namedTypes))
+
+	// Generate typeToString
+	fatalIfErr(typeToString.Execute(b, numberedTypes))
+
+	// Generate headerFunc
+	fatalIfErr(headerFunc.Execute(b, namedTypes))
+
+	// Generate len()
+	fmt.Fprint(b, "// len() functions\n")
+	for _, name := range namedTypes {
+		if _, ok := skipLen[name]; ok {
+			continue
+		}
+		o := scope.Lookup(name)
+		st, isEmbedded := getTypeStruct(o.Type(), scope)
+		if isEmbedded {
+			continue
+		}
+		fmt.Fprintf(b, "func (rr *%s) len() int {\n", name)
+		fmt.Fprintf(b, "l := rr.Hdr.len()\n")
+		for i := 1; i < st.NumFields(); i++ {
+			o := func(s string) { fmt.Fprintf(b, s, st.Field(i).Name()) }
+
+			if _, ok := st.Field(i).Type().(*types.Slice); ok {
+				switch st.Tag(i) {
+				case `dns:"-"`:
+					// ignored
+				case `dns:"cdomain-name"`, `dns:"domain-name"`, `dns:"txt"`:
+					o("for _, x := range rr.%s { l += len(x) + 1 }\n")
+				default:
+					log.Fatalln(name, st.Field(i).Name(), st.Tag(i))
+				}
+				continue
+			}
+
+			switch st.Tag(i) {
+			case `dns:"-"`:
+				// ignored
+			case `dns:"cdomain-name"`, `dns:"domain-name"`:
+				o("l += len(rr.%s) + 1\n")
+			case `dns:"octet"`:
+				o("l += len(rr.%s)\n")
+			case `dns:"base64"`:
+				o("l += base64.StdEncoding.DecodedLen(len(rr.%s))\n")
+			case `dns:"size-hex"`, `dns:"hex"`:
+				o("l += len(rr.%s)/2 + 1\n")
+			case `dns:"a"`:
+				o("l += net.IPv4len // %s\n")
+			case `dns:"aaaa"`:
+				o("l += net.IPv6len // %s\n")
+			case `dns:"txt"`:
+				o("for _, t := range rr.%s { l += len(t) + 1 }\n")
+			case `dns:"uint48"`:
+				o("l += 6 // %s\n")
+			case "":
+				switch st.Field(i).Type().(*types.Basic).Kind() {
+				case types.Uint8:
+					o("l += 1 // %s\n")
+				case types.Uint16:
+					o("l += 2 // %s\n")
+				case types.Uint32:
+					o("l += 4 // %s\n")
+				case types.Uint64:
+					o("l += 8 // %s\n")
+				case types.String:
+					o("l += len(rr.%s) + 1\n")
+				default:
+					log.Fatalln(name, st.Field(i).Name())
+				}
+			default:
+				log.Fatalln(name, st.Field(i).Name(), st.Tag(i))
+			}
+		}
+		fmt.Fprintf(b, "return l }\n")
+	}
+
+	res, err := format.Source(b.Bytes())
+	fatalIfErr(err)
+
+	f, err := os.Create("types_auto.go")
+	fatalIfErr(err)
+	defer f.Close()
+	f.Write(res)
+}
+
+func fatalIfErr(err error) {
+	if err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/update_test.go b/update_test.go
index c5767b72..8d654185 100644
--- a/update_test.go
+++ b/update_test.go
@@ -9,7 +9,8 @@ func TestDynamicUpdateParsing(t *testing.T) {
 	prefix := "example.com. IN "
 	for _, typ := range TypeToString {
 		if typ == "OPT" || typ == "AXFR" || typ == "IXFR" || typ == "ANY" || typ == "TKEY" ||
-			typ == "TSIG" || typ == "ISDN" || typ == "UNSPEC" || typ == "NULL" || typ == "ATMA" {
+			typ == "TSIG" || typ == "ISDN" || typ == "UNSPEC" || typ == "NULL" || typ == "ATMA" ||
+			typ == "Reserved" || typ == "None" || typ == "NXT" || typ == "MAILB" || typ == "MAILA" {
 			continue
 		}
 		r, err := NewRR(prefix + typ)