Implement compressible domain names
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parent
974c28d1b1
commit
b5d73f1eff
2
dns.go
2
dns.go
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@ -173,7 +173,7 @@ type Exchange struct {
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// There are many types of messages,
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// but they all share the same header.
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type RR_Header struct {
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Name string "domain-name"
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Name string "cdomain-name"
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Rrtype uint16
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Class uint16
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Ttl uint32
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52
msg.go
52
msg.go
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@ -26,7 +26,7 @@ import (
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"time"
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)
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const MaxCompressionOffset = 2 << 13 // We have 14 bits for the compression pointer
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const MaxCompressionOffset = 2 << 13 // We have 14 bits for the compression pointer
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var (
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ErrUnpack error = &Error{Err: "unpacking failed"}
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@ -214,21 +214,21 @@ func PackDomainName(s string, msg []byte, off int, compression map[string]int) (
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return lenmsg, false
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}
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msg[off] = byte(i - begin)
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offset := off
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offset := off
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off++
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for j := begin; j < i; j++ {
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msg[off] = bs[j]
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off++
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}
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str, _, ok := UnpackDomainName(msg, offset)
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if !ok {
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// hmmm how can this be?
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}
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if compression != nil {
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if _, ok := compression[str]; !ok {
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compression[str] = offset
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}
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}
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str, _, ok := UnpackDomainName(msg, offset)
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if !ok {
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// hmmm how can this be?
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}
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if compression != nil {
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if _, ok := compression[str]; !ok {
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compression[str] = offset
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}
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}
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begin = i + 1
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}
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}
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@ -462,7 +462,13 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
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copy(msg[off:off+len(b64)], b64)
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off += len(b64)
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case "domain-name":
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off, ok = PackDomainName(s, msg, off, compression)
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fallthrough // No compression
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case "cdomain-name":
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if val.Type().Field(i).Tag == "cdomain-name" {
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off, ok = PackDomainName(s, msg, off, compression)
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} else {
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off, ok = PackDomainName(s, msg, off, nil)
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}
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if !ok {
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//fmt.Fprintf(os.Stderr, "dns: overflow packing domain-name")
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return lenmsg, false
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@ -476,10 +482,10 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
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//fmt.Fprintf(os.Stderr, "dns: overflow packing (size-)hex string")
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return lenmsg, false
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}
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if off+hex.DecodedLen(len(s)) > lenmsg {
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// Overflow
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return lenmsg, false
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}
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if off+hex.DecodedLen(len(s)) > lenmsg {
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// Overflow
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return lenmsg, false
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}
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copy(msg[off:off+hex.DecodedLen(len(s))], h)
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off += hex.DecodedLen(len(s))
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case "size":
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@ -664,10 +670,10 @@ func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok boo
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case "hex":
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// Rest of the RR is hex encoded, network order an issue here?
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rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
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if off+rdlength > lenmsg {
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// too large
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return lenmsg, false
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}
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if off+rdlength > lenmsg {
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// too large
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return lenmsg, false
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}
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var consumed int
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switch val.Type().Name() {
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case "RR_DS":
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@ -956,7 +962,7 @@ func (h *MsgHdr) String() string {
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// Pack a msg: convert it to wire format.
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func (dns *Msg) Pack() (msg []byte, ok bool) {
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var dh Header
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compression := make(map[string]int) // Compression pointer mappings
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compression := make(map[string]int) // Compression pointer mappings
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// Convert convenient Msg into wire-like Header.
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dh.Id = dns.Id
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@ -997,7 +1003,7 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
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dh.Nscount = uint16(len(ns))
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dh.Arcount = uint16(len(extra))
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// TODO: still too much, but better than 64K
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// TODO: still too much, but better than 64K
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msg = make([]byte, dns.Len()*6)
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// Pack it in: header and then the pieces.
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@ -1022,7 +1028,7 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
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if !ok {
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return nil, false
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}
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fmt.Printf("**%v\n", compression)
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fmt.Printf("**%v\n", compression)
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return msg[:off], true
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}
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@ -4,10 +4,6 @@
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package dns
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import (
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"fmt"
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)
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// Function defined in this subpackage work on []byte and but still
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// provide some higher level functions.
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24
types.go
24
types.go
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@ -129,7 +129,7 @@ const (
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// DNS queries.
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type Question struct {
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Name string "domain-name" // "domain-name" specifies encoding
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Name string "cdomain-name" // "cdomain-name" specifies encoding (and may be compressed)
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Qtype uint16
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Qclass uint16
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}
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@ -174,7 +174,7 @@ func (rr *RR_ANY) Len() int {
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type RR_CNAME struct {
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Hdr RR_Header
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Cname string "domain-name"
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Cname string "cdomain-name"
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}
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func (rr *RR_CNAME) Header() *RR_Header {
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@ -210,7 +210,7 @@ func (rr *RR_HINFO) Len() int {
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type RR_MB struct {
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Hdr RR_Header
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Mb string "domain-name"
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Mb string "cdomain-name"
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}
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func (rr *RR_MB) Header() *RR_Header {
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@ -228,7 +228,7 @@ func (rr *RR_MB) Len() int {
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type RR_MG struct {
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Hdr RR_Header
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Mg string "domain-name"
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Mg string "cdomain-name"
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}
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func (rr *RR_MG) Header() *RR_Header {
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@ -246,8 +246,8 @@ func (rr *RR_MG) Len() int {
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type RR_MINFO struct {
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Hdr RR_Header
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Rmail string "domain-name"
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Email string "domain-name"
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Rmail string "cdomain-name"
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Email string "cdomain-name"
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}
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func (rr *RR_MINFO) Header() *RR_Header {
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@ -266,7 +266,7 @@ func (rr *RR_MINFO) Len() int {
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type RR_MR struct {
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Hdr RR_Header
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Mr string "domain-name"
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Mr string "cdomain-name"
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}
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func (rr *RR_MR) Header() *RR_Header {
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@ -285,7 +285,7 @@ func (rr *RR_MR) Len() int {
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type RR_MX struct {
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Hdr RR_Header
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Pref uint16
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Mx string "domain-name"
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Mx string "cdomain-name"
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}
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func (rr *RR_MX) Header() *RR_Header {
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@ -303,7 +303,7 @@ func (rr *RR_MX) Len() int {
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type RR_NS struct {
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Hdr RR_Header
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Ns string "domain-name"
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Ns string "cdomain-name"
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}
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func (rr *RR_NS) Header() *RR_Header {
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@ -321,7 +321,7 @@ func (rr *RR_NS) Len() int {
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type RR_PTR struct {
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Hdr RR_Header
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Ptr string "domain-name"
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Ptr string "cdomain-name"
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}
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func (rr *RR_PTR) Header() *RR_Header {
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@ -339,8 +339,8 @@ func (rr *RR_PTR) Len() int {
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type RR_SOA struct {
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Hdr RR_Header
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Ns string "domain-name"
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Mbox string "domain-name"
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Ns string "cdomain-name"
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Mbox string "cdomain-name"
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Serial uint32
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Refresh uint32
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Retry uint32
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