diff options
Diffstat (limited to 'vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/sig0.go')
| -rw-r--r-- | vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/sig0.go | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/sig0.go b/vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/sig0.go new file mode 100644 index 000000000..f31e9e684 --- /dev/null +++ b/vendor/github.com/rsc/letsencrypt/vendor/github.com/miekg/dns/sig0.go @@ -0,0 +1,218 @@ +package dns + +import ( + "crypto" + "crypto/dsa" + "crypto/ecdsa" + "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 || len(rr.SignerName) == 0 || rr.Algorithm == 0 { + return nil, ErrKey + } + rr.Header().Rrtype = TypeSIG + rr.Header().Class = ClassANY + rr.Header().Ttl = 0 + rr.Header().Name = "." + rr.OrigTtl = 0 + rr.TypeCovered = 0 + rr.Labels = 0 + + buf := make([]byte, m.Len()+rr.len()) + 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)] + + hash, ok := AlgorithmToHash[rr.Algorithm] + if !ok { + return nil, ErrAlg + } + + hasher := hash.New() + // Write SIG rdata + hasher.Write(buf[len(mbuf)+1+2+2+4+2:]) + // Write message + hasher.Write(buf[:len(mbuf)]) + + signature, err := sign(k, hasher.Sum(nil), hash, 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 || len(rr.SignerName) == 0 || rr.Algorithm == 0 { + return ErrKey + } + + var hash crypto.Hash + switch rr.Algorithm { + case DSA, RSASHA1: + hash = crypto.SHA1 + case RSASHA256, ECDSAP256SHA256: + hash = crypto.SHA256 + case ECDSAP384SHA384: + hash = crypto.SHA384 + case RSASHA512: + hash = crypto.SHA512 + default: + return ErrAlg + } + hasher := hash.New() + + 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 := 12 + var err error + 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 + } + var rdlen uint16 + 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.ToLower(signername) != strings.ToLower(k.Header().Name) { + return &Error{err: "signer name doesn't match key name"} + } + sigend := offset + hasher.Write(buf[sigstart:sigend]) + hasher.Write(buf[:10]) + hasher.Write([]byte{ + byte((adc - 1) << 8), + byte(adc - 1), + }) + hasher.Write(buf[12:bodyend]) + + hashed := hasher.Sum(nil) + sig := buf[sigend:] + switch k.Algorithm { + case DSA: + pk := k.publicKeyDSA() + sig = sig[1:] + r := big.NewInt(0) + r.SetBytes(sig[:len(sig)/2]) + s := big.NewInt(0) + s.SetBytes(sig[len(sig)/2:]) + if pk != nil { + if dsa.Verify(pk, hashed, r, s) { + return nil + } + return ErrSig + } + case RSASHA1, RSASHA256, RSASHA512: + pk := k.publicKeyRSA() + if pk != nil { + return rsa.VerifyPKCS1v15(pk, hash, hashed, sig) + } + case ECDSAP256SHA256, ECDSAP384SHA384: + pk := k.publicKeyECDSA() + r := big.NewInt(0) + r.SetBytes(sig[:len(sig)/2]) + s := big.NewInt(0) + s.SetBytes(sig[len(sig)/2:]) + if pk != nil { + if ecdsa.Verify(pk, hashed, r, s) { + return nil + } + return ErrSig + } + } + return ErrKeyAlg +} |