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Implement compressible domain names

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This commit is contained in:
Miek Gieben 2012-01-11 11:19:07 +01:00
parent 974c28d1b1
commit b5d73f1eff
4 changed files with 42 additions and 40 deletions
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2
dns.go
View File

@ -173,7 +173,7 @@ type Exchange struct {
// There are many types of messages, // There are many types of messages,
// but they all share the same header. // but they all share the same header.
type RR_Header struct { type RR_Header struct {
Name string "domain-name" Name string "cdomain-name"
Rrtype uint16 Rrtype uint16
Class uint16 Class uint16
Ttl uint32 Ttl uint32

52
msg.go
View File

@ -26,7 +26,7 @@ import (
"time" "time"
) )
const MaxCompressionOffset = 2 << 13 // We have 14 bits for the compression pointer const MaxCompressionOffset = 2 << 13 // We have 14 bits for the compression pointer
var ( var (
ErrUnpack error = &Error{Err: "unpacking failed"} ErrUnpack error = &Error{Err: "unpacking failed"}
@ -214,21 +214,21 @@ func PackDomainName(s string, msg []byte, off int, compression map[string]int) (
return lenmsg, false return lenmsg, false
} }
msg[off] = byte(i - begin) msg[off] = byte(i - begin)
offset := off offset := off
off++ off++
for j := begin; j < i; j++ { for j := begin; j < i; j++ {
msg[off] = bs[j] msg[off] = bs[j]
off++ off++
} }
str, _, ok := UnpackDomainName(msg, offset) str, _, ok := UnpackDomainName(msg, offset)
if !ok { if !ok {
// hmmm how can this be? // hmmm how can this be?
} }
if compression != nil { if compression != nil {
if _, ok := compression[str]; !ok { if _, ok := compression[str]; !ok {
compression[str] = offset compression[str] = offset
} }
} }
begin = i + 1 begin = i + 1
} }
} }
@ -462,7 +462,13 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
copy(msg[off:off+len(b64)], b64) copy(msg[off:off+len(b64)], b64)
off += len(b64) off += len(b64)
case "domain-name": case "domain-name":
off, ok = PackDomainName(s, msg, off, compression) fallthrough // No compression
case "cdomain-name":
if val.Type().Field(i).Tag == "cdomain-name" {
off, ok = PackDomainName(s, msg, off, compression)
} else {
off, ok = PackDomainName(s, msg, off, nil)
}
if !ok { if !ok {
//fmt.Fprintf(os.Stderr, "dns: overflow packing domain-name") //fmt.Fprintf(os.Stderr, "dns: overflow packing domain-name")
return lenmsg, false return lenmsg, false
@ -476,10 +482,10 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
//fmt.Fprintf(os.Stderr, "dns: overflow packing (size-)hex string") //fmt.Fprintf(os.Stderr, "dns: overflow packing (size-)hex string")
return lenmsg, false return lenmsg, false
} }
if off+hex.DecodedLen(len(s)) > lenmsg { if off+hex.DecodedLen(len(s)) > lenmsg {
// Overflow // Overflow
return lenmsg, false return lenmsg, false
} }
copy(msg[off:off+hex.DecodedLen(len(s))], h) copy(msg[off:off+hex.DecodedLen(len(s))], h)
off += hex.DecodedLen(len(s)) off += hex.DecodedLen(len(s))
case "size": case "size":
@ -664,10 +670,10 @@ func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok boo
case "hex": case "hex":
// Rest of the RR is hex encoded, network order an issue here? // Rest of the RR is hex encoded, network order an issue here?
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint()) rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
if off+rdlength > lenmsg { if off+rdlength > lenmsg {
// too large // too large
return lenmsg, false return lenmsg, false
} }
var consumed int var consumed int
switch val.Type().Name() { switch val.Type().Name() {
case "RR_DS": case "RR_DS":
@ -956,7 +962,7 @@ func (h *MsgHdr) String() string {
// Pack a msg: convert it to wire format. // Pack a msg: convert it to wire format.
func (dns *Msg) Pack() (msg []byte, ok bool) { func (dns *Msg) Pack() (msg []byte, ok bool) {
var dh Header var dh Header
compression := make(map[string]int) // Compression pointer mappings compression := make(map[string]int) // Compression pointer mappings
// Convert convenient Msg into wire-like Header. // Convert convenient Msg into wire-like Header.
dh.Id = dns.Id dh.Id = dns.Id
@ -997,7 +1003,7 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
dh.Nscount = uint16(len(ns)) dh.Nscount = uint16(len(ns))
dh.Arcount = uint16(len(extra)) dh.Arcount = uint16(len(extra))
// TODO: still too much, but better than 64K // TODO: still too much, but better than 64K
msg = make([]byte, dns.Len()*6) msg = make([]byte, dns.Len()*6)
// Pack it in: header and then the pieces. // Pack it in: header and then the pieces.
@ -1022,7 +1028,7 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
if !ok { if !ok {
return nil, false return nil, false
} }
fmt.Printf("**%v\n", compression) fmt.Printf("**%v\n", compression)
return msg[:off], true return msg[:off], true
} }

4
rawmsg.go
View File

@ -4,10 +4,6 @@
package dns package dns
import (
"fmt"
)
// Function defined in this subpackage work on []byte and but still // Function defined in this subpackage work on []byte and but still
// provide some higher level functions. // provide some higher level functions.

24
types.go
View File

@ -129,7 +129,7 @@ const (
// DNS queries. // DNS queries.
type Question struct { type Question struct {
Name string "domain-name" // "domain-name" specifies encoding Name string "cdomain-name" // "cdomain-name" specifies encoding (and may be compressed)
Qtype uint16 Qtype uint16
Qclass uint16 Qclass uint16
} }
@ -174,7 +174,7 @@ func (rr *RR_ANY) Len() int {
type RR_CNAME struct { type RR_CNAME struct {
Hdr RR_Header Hdr RR_Header
Cname string "domain-name" Cname string "cdomain-name"
} }
func (rr *RR_CNAME) Header() *RR_Header { func (rr *RR_CNAME) Header() *RR_Header {
@ -210,7 +210,7 @@ func (rr *RR_HINFO) Len() int {
type RR_MB struct { type RR_MB struct {
Hdr RR_Header Hdr RR_Header
Mb string "domain-name" Mb string "cdomain-name"
} }
func (rr *RR_MB) Header() *RR_Header { func (rr *RR_MB) Header() *RR_Header {
@ -228,7 +228,7 @@ func (rr *RR_MB) Len() int {
type RR_MG struct { type RR_MG struct {
Hdr RR_Header Hdr RR_Header
Mg string "domain-name" Mg string "cdomain-name"
} }
func (rr *RR_MG) Header() *RR_Header { func (rr *RR_MG) Header() *RR_Header {
@ -246,8 +246,8 @@ func (rr *RR_MG) Len() int {
type RR_MINFO struct { type RR_MINFO struct {
Hdr RR_Header Hdr RR_Header
Rmail string "domain-name" Rmail string "cdomain-name"
Email string "domain-name" Email string "cdomain-name"
} }
func (rr *RR_MINFO) Header() *RR_Header { func (rr *RR_MINFO) Header() *RR_Header {
@ -266,7 +266,7 @@ func (rr *RR_MINFO) Len() int {
type RR_MR struct { type RR_MR struct {
Hdr RR_Header Hdr RR_Header
Mr string "domain-name" Mr string "cdomain-name"
} }
func (rr *RR_MR) Header() *RR_Header { func (rr *RR_MR) Header() *RR_Header {
@ -285,7 +285,7 @@ func (rr *RR_MR) Len() int {
type RR_MX struct { type RR_MX struct {
Hdr RR_Header Hdr RR_Header
Pref uint16 Pref uint16
Mx string "domain-name" Mx string "cdomain-name"
} }
func (rr *RR_MX) Header() *RR_Header { func (rr *RR_MX) Header() *RR_Header {
@ -303,7 +303,7 @@ func (rr *RR_MX) Len() int {
type RR_NS struct { type RR_NS struct {
Hdr RR_Header Hdr RR_Header
Ns string "domain-name" Ns string "cdomain-name"
} }
func (rr *RR_NS) Header() *RR_Header { func (rr *RR_NS) Header() *RR_Header {
@ -321,7 +321,7 @@ func (rr *RR_NS) Len() int {
type RR_PTR struct { type RR_PTR struct {
Hdr RR_Header Hdr RR_Header
Ptr string "domain-name" Ptr string "cdomain-name"
} }
func (rr *RR_PTR) Header() *RR_Header { func (rr *RR_PTR) Header() *RR_Header {
@ -339,8 +339,8 @@ func (rr *RR_PTR) Len() int {
type RR_SOA struct { type RR_SOA struct {
Hdr RR_Header Hdr RR_Header
Ns string "domain-name" Ns string "cdomain-name"
Mbox string "domain-name" Mbox string "cdomain-name"
Serial uint32 Serial uint32
Refresh uint32 Refresh uint32
Retry uint32 Retry uint32