[chore] Validate/set account domain (#619)

* add miekg/dns dependency

* set/validate accountDomain

vendor/github.com/miekg/dns/sig0.go

@@ -0,0 +1,194 @@
+package dns
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/ed25519"
+	"crypto/rsa"
+	"encoding/binary"
+	"math/big"
+	"strings"
+	"time"
+)
+
+// Sign signs a dns.Msg. It fills the signature with the appropriate data.
+// The SIG record should have the SignerName, KeyTag, Algorithm, Inception
+// and Expiration set.
+func (rr *SIG) Sign(k crypto.Signer, m *Msg) ([]byte, error) {
+	if k == nil {
+		return nil, ErrPrivKey
+	}
+	if rr.KeyTag == 0 || rr.SignerName == "" || rr.Algorithm == 0 {
+		return nil, ErrKey
+	}
+
+	rr.Hdr = RR_Header{Name: ".", Rrtype: TypeSIG, Class: ClassANY, Ttl: 0}
+	rr.OrigTtl, rr.TypeCovered, rr.Labels = 0, 0, 0
+
+	buf := make([]byte, m.Len()+Len(rr))
+	mbuf, err := m.PackBuffer(buf)
+	if err != nil {
+		return nil, err
+	}
+	if &buf[0] != &mbuf[0] {
+		return nil, ErrBuf
+	}
+	off, err := PackRR(rr, buf, len(mbuf), nil, false)
+	if err != nil {
+		return nil, err
+	}
+	buf = buf[:off:cap(buf)]
+
+	h, cryptohash, err := hashFromAlgorithm(rr.Algorithm)
+	if err != nil {
+		return nil, err
+	}
+
+	// Write SIG rdata
+	h.Write(buf[len(mbuf)+1+2+2+4+2:])
+	// Write message
+	h.Write(buf[:len(mbuf)])
+
+	signature, err := sign(k, h.Sum(nil), cryptohash, rr.Algorithm)
+	if err != nil {
+		return nil, err
+	}
+
+	rr.Signature = toBase64(signature)
+
+	buf = append(buf, signature...)
+	if len(buf) > int(^uint16(0)) {
+		return nil, ErrBuf
+	}
+	// Adjust sig data length
+	rdoff := len(mbuf) + 1 + 2 + 2 + 4
+	rdlen := binary.BigEndian.Uint16(buf[rdoff:])
+	rdlen += uint16(len(signature))
+	binary.BigEndian.PutUint16(buf[rdoff:], rdlen)
+	// Adjust additional count
+	adc := binary.BigEndian.Uint16(buf[10:])
+	adc++
+	binary.BigEndian.PutUint16(buf[10:], adc)
+	return buf, nil
+}
+
+// Verify validates the message buf using the key k.
+// It's assumed that buf is a valid message from which rr was unpacked.
+func (rr *SIG) Verify(k *KEY, buf []byte) error {
+	if k == nil {
+		return ErrKey
+	}
+	if rr.KeyTag == 0 || rr.SignerName == "" || rr.Algorithm == 0 {
+		return ErrKey
+	}
+
+	h, cryptohash, err := hashFromAlgorithm(rr.Algorithm)
+	if err != nil {
+		return err
+	}
+
+	buflen := len(buf)
+	qdc := binary.BigEndian.Uint16(buf[4:])
+	anc := binary.BigEndian.Uint16(buf[6:])
+	auc := binary.BigEndian.Uint16(buf[8:])
+	adc := binary.BigEndian.Uint16(buf[10:])
+	offset := headerSize
+	for i := uint16(0); i < qdc && offset < buflen; i++ {
+		_, offset, err = UnpackDomainName(buf, offset)
+		if err != nil {
+			return err
+		}
+		// Skip past Type and Class
+		offset += 2 + 2
+	}
+	for i := uint16(1); i < anc+auc+adc && offset < buflen; i++ {
+		_, offset, err = UnpackDomainName(buf, offset)
+		if err != nil {
+			return err
+		}
+		// Skip past Type, Class and TTL
+		offset += 2 + 2 + 4
+		if offset+1 >= buflen {
+			continue
+		}
+		rdlen := binary.BigEndian.Uint16(buf[offset:])
+		offset += 2
+		offset += int(rdlen)
+	}
+	if offset >= buflen {
+		return &Error{err: "overflowing unpacking signed message"}
+	}
+
+	// offset should be just prior to SIG
+	bodyend := offset
+	// owner name SHOULD be root
+	_, offset, err = UnpackDomainName(buf, offset)
+	if err != nil {
+		return err
+	}
+	// Skip Type, Class, TTL, RDLen
+	offset += 2 + 2 + 4 + 2
+	sigstart := offset
+	// Skip Type Covered, Algorithm, Labels, Original TTL
+	offset += 2 + 1 + 1 + 4
+	if offset+4+4 >= buflen {
+		return &Error{err: "overflow unpacking signed message"}
+	}
+	expire := binary.BigEndian.Uint32(buf[offset:])
+	offset += 4
+	incept := binary.BigEndian.Uint32(buf[offset:])
+	offset += 4
+	now := uint32(time.Now().Unix())
+	if now < incept || now > expire {
+		return ErrTime
+	}
+	// Skip key tag
+	offset += 2
+	var signername string
+	signername, offset, err = UnpackDomainName(buf, offset)
+	if err != nil {
+		return err
+	}
+	// If key has come from the DNS name compression might
+	// have mangled the case of the name
+	if !strings.EqualFold(signername, k.Header().Name) {
+		return &Error{err: "signer name doesn't match key name"}
+	}
+	sigend := offset
+	h.Write(buf[sigstart:sigend])
+	h.Write(buf[:10])
+	h.Write([]byte{
+		byte((adc - 1) << 8),
+		byte(adc - 1),
+	})
+	h.Write(buf[12:bodyend])
+
+	hashed := h.Sum(nil)
+	sig := buf[sigend:]
+	switch k.Algorithm {
+	case RSASHA1, RSASHA256, RSASHA512:
+		pk := k.publicKeyRSA()
+		if pk != nil {
+			return rsa.VerifyPKCS1v15(pk, cryptohash, hashed, sig)
+		}
+	case ECDSAP256SHA256, ECDSAP384SHA384:
+		pk := k.publicKeyECDSA()
+		r := new(big.Int).SetBytes(sig[:len(sig)/2])
+		s := new(big.Int).SetBytes(sig[len(sig)/2:])
+		if pk != nil {
+			if ecdsa.Verify(pk, hashed, r, s) {
+				return nil
+			}
+			return ErrSig
+		}
+	case ED25519:
+		pk := k.publicKeyED25519()
+		if pk != nil {
+			if ed25519.Verify(pk, hashed, sig) {
+				return nil
+			}
+			return ErrSig
+		}
+	}
+	return ErrKeyAlg
+}