1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
package dns
import (
"crypto/sha256"
"crypto/sha512"
"crypto/x509"
"encoding/hex"
"errors"
"io"
"net"
"strconv"
)
// CertificateToDANE converts a certificate to a hex string as used in the TLSA record.
func CertificateToDANE(selector, matchingType uint8, cert *x509.Certificate) (string, error) {
switch matchingType {
case 0:
switch selector {
case 0:
return hex.EncodeToString(cert.Raw), nil
case 1:
return hex.EncodeToString(cert.RawSubjectPublicKeyInfo), nil
}
case 1:
h := sha256.New()
switch selector {
case 0:
io.WriteString(h, string(cert.Raw))
return hex.EncodeToString(h.Sum(nil)), nil
case 1:
io.WriteString(h, string(cert.RawSubjectPublicKeyInfo))
return hex.EncodeToString(h.Sum(nil)), nil
}
case 2:
h := sha512.New()
switch selector {
case 0:
io.WriteString(h, string(cert.Raw))
return hex.EncodeToString(h.Sum(nil)), nil
case 1:
io.WriteString(h, string(cert.RawSubjectPublicKeyInfo))
return hex.EncodeToString(h.Sum(nil)), nil
}
}
return "", errors.New("dns: bad TLSA MatchingType or TLSA Selector")
}
// Sign creates a TLSA record from an SSL certificate.
func (r *TLSA) Sign(usage, selector, matchingType int, cert *x509.Certificate) (err error) {
r.Hdr.Rrtype = TypeTLSA
r.Usage = uint8(usage)
r.Selector = uint8(selector)
r.MatchingType = uint8(matchingType)
r.Certificate, err = CertificateToDANE(r.Selector, r.MatchingType, cert)
if err != nil {
return err
}
return nil
}
// Verify verifies a TLSA record against an SSL certificate. If it is OK
// a nil error is returned.
func (r *TLSA) Verify(cert *x509.Certificate) error {
c, err := CertificateToDANE(r.Selector, r.MatchingType, cert)
if err != nil {
return err // Not also ErrSig?
}
if r.Certificate == c {
return nil
}
return ErrSig // ErrSig, really?
}
// TLSAName returns the ownername of a TLSA resource record as per the
// rules specified in RFC 6698, Section 3.
func TLSAName(name, service, network string) (string, error) {
if !IsFqdn(name) {
return "", ErrFqdn
}
p, err := net.LookupPort(network, service)
if err != nil {
return "", err
}
return "_" + strconv.Itoa(p) + "._" + network + "." + name, nil
}
|
