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119 lines
2.7 KiB
119 lines
2.7 KiB
package dns
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import (
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"crypto/sha1"
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"hash"
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"io"
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"strings"
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)
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type saltWireFmt struct {
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Salt string `dns:"size-hex"`
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}
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// HashName hashes a string (label) according to RFC 5155. It returns the hashed string in uppercase.
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func HashName(label string, ha uint8, iter uint16, salt string) string {
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saltwire := new(saltWireFmt)
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saltwire.Salt = salt
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wire := make([]byte, DefaultMsgSize)
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n, err := packSaltWire(saltwire, wire)
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if err != nil {
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return ""
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}
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wire = wire[:n]
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name := make([]byte, 255)
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off, err := PackDomainName(strings.ToLower(label), name, 0, nil, false)
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if err != nil {
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return ""
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}
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name = name[:off]
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var s hash.Hash
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switch ha {
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case SHA1:
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s = sha1.New()
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default:
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return ""
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}
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// k = 0
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name = append(name, wire...)
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io.WriteString(s, string(name))
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nsec3 := s.Sum(nil)
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// k > 0
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for k := uint16(0); k < iter; k++ {
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s.Reset()
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nsec3 = append(nsec3, wire...)
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io.WriteString(s, string(nsec3))
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nsec3 = s.Sum(nil)
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}
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return toBase32(nsec3)
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}
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// Denialer is an interface that should be implemented by types that are used to denial
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// answers in DNSSEC.
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type Denialer interface {
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// Cover will check if the (unhashed) name is being covered by this NSEC or NSEC3.
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Cover(name string) bool
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// Match will check if the ownername matches the (unhashed) name for this NSEC3 or NSEC3.
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Match(name string) bool
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}
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// Cover implements the Denialer interface.
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func (rr *NSEC) Cover(name string) bool {
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return true
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}
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// Match implements the Denialer interface.
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func (rr *NSEC) Match(name string) bool {
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return true
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}
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// Cover implements the Denialer interface.
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func (rr *NSEC3) Cover(name string) bool {
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// FIXME(miek): check if the zones match
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// FIXME(miek): check if we're not dealing with parent nsec3
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hname := HashName(name, rr.Hash, rr.Iterations, rr.Salt)
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labels := Split(rr.Hdr.Name)
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if len(labels) < 2 {
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return false
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}
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hash := strings.ToUpper(rr.Hdr.Name[labels[0] : labels[1]-1]) // -1 to remove the dot
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if hash == rr.NextDomain {
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return false // empty interval
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}
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if hash > rr.NextDomain { // last name, points to apex
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// hname > hash
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// hname > rr.NextDomain
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// TODO(miek)
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}
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if hname <= hash {
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return false
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}
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if hname >= rr.NextDomain {
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return false
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}
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return true
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}
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// Match implements the Denialer interface.
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func (rr *NSEC3) Match(name string) bool {
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// FIXME(miek): Check if we are in the same zone
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hname := HashName(name, rr.Hash, rr.Iterations, rr.Salt)
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labels := Split(rr.Hdr.Name)
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if len(labels) < 2 {
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return false
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}
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hash := strings.ToUpper(rr.Hdr.Name[labels[0] : labels[1]-1]) // -1 to remove the .
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if hash == hname {
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return true
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}
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return false
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}
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func packSaltWire(sw *saltWireFmt, msg []byte) (int, error) {
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off, err := packStringHex(sw.Salt, msg, 0)
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if err != nil {
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return off, err
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}
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return off, nil
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}
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