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Fix compression

This commit is contained in:
Miek Gieben 2012-01-11 14:09:47 +01:00
parent ba869578fd
commit 6bf1255177
2 changed files with 8 additions and 15 deletions
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2
_examples/mx/mx.go
View File

@ -27,7 +27,6 @@ func main() {
fmt.Printf("%s\n", err.Error())
os.Exit(1)
}
if r.Rcode != dns.RcodeSuccess {
fmt.Printf(" *** invalid answer name %s after MX query for %s\n", os.Args[1], os.Args[1])
os.Exit(1)
@ -38,7 +37,6 @@ func main() {
}
println(r.String())
buf, _ := r.Pack()
buf = dns.Compress(buf)
r1 := new(dns.Msg)
ok := r1.Unpack(buf)
if ok {

21
msg.go
View File

@ -18,7 +18,6 @@ import (
"encoding/base32"
"encoding/base64"
"encoding/hex"
"fmt"
"math/rand"
"net"
"reflect"
@ -190,7 +189,7 @@ func PackDomainName(s string, msg []byte, off int, compression map[string]int) (
// Except for escaped dots (\.), which are normal dots.
// There is also a trailing zero.
// Check that we have all the space we need.
tot := len(s) + 1 // TODO: this fails for compression...
tot := len(s) + 1 // TODO: this too much for compression...
if off+tot > lenmsg {
return lenmsg, false
}
@ -223,15 +222,11 @@ func PackDomainName(s string, msg []byte, off int, compression map[string]int) (
msg[off] = bs[j]
off++
}
str, _, ok := UnpackDomainName(msg, offset)
if !ok {
// hmmm how can this be?
}
if compression != nil {
if p, ok := compression[str]; !ok {
// Only offsets small than this can be used.
if p, ok := compression[string(bs[begin:])]; !ok {
// Only offsets smaller than this can be used.
if offset < maxCompressionOffset {
compression[str] = offset
compression[string(bs[begin:])] = offset
}
} else {
// The first hit is the longest matching dname
@ -251,11 +246,11 @@ func PackDomainName(s string, msg []byte, off int, compression map[string]int) (
if string(bs) == "." {
return off, true
}
// If we did compression and we did find something, fix that here
// If we did compression and we find something at the pointer here
if pointer != -1 {
// We have two bytes to put the pointer in
// We have two bytes (14 bits) to put the pointer in
msg[nameoffset], msg[nameoffset+1] = packUint16(uint16(pointer ^ 0xC000))
off = nameoffset + 1
off = nameoffset + 2
return off, true
}
msg[off] = 0
@ -730,6 +725,7 @@ func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok boo
}
s = unpackBase64(msg[off : off+rdlength-consumed])
off += rdlength - consumed
case "cdomain-name": fallthrough
case "domain-name":
s, off, ok = UnpackDomainName(msg, off)
if !ok {
@ -1050,7 +1046,6 @@ func (dns *Msg) Pack() (msg []byte, ok bool) {
if !ok {
return nil, false
}
fmt.Printf("**%v\n", compression)
return msg[:off], true
}