298 lines
6.7 KiB
Go
298 lines
6.7 KiB
Go
package dns
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import (
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"bytes"
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"crypto"
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"crypto/dsa"
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"crypto/ecdsa"
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"crypto/rsa"
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"io"
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"math/big"
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"strconv"
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"strings"
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"golang.org/x/crypto/ed25519"
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)
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// NewPrivateKey returns a PrivateKey by parsing the string s.
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// s should be in the same form of the BIND private key files.
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func (k *DNSKEY) NewPrivateKey(s string) (crypto.PrivateKey, error) {
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if s == "" || s[len(s)-1] != '\n' { // We need a closing newline
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return k.ReadPrivateKey(strings.NewReader(s+"\n"), "")
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}
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return k.ReadPrivateKey(strings.NewReader(s), "")
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}
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// ReadPrivateKey reads a private key from the io.Reader q. The string file is
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// only used in error reporting.
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// The public key must be known, because some cryptographic algorithms embed
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// the public inside the privatekey.
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func (k *DNSKEY) ReadPrivateKey(q io.Reader, file string) (crypto.PrivateKey, error) {
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m, err := parseKey(q, file)
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if m == nil {
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return nil, err
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}
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if _, ok := m["private-key-format"]; !ok {
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return nil, ErrPrivKey
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}
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if m["private-key-format"] != "v1.2" && m["private-key-format"] != "v1.3" {
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return nil, ErrPrivKey
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}
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// TODO(mg): check if the pubkey matches the private key
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algo, err := strconv.ParseUint(strings.SplitN(m["algorithm"], " ", 2)[0], 10, 8)
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if err != nil {
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return nil, ErrPrivKey
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}
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switch uint8(algo) {
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case DSA:
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priv, err := readPrivateKeyDSA(m)
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if err != nil {
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return nil, err
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}
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pub := k.publicKeyDSA()
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if pub == nil {
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return nil, ErrKey
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}
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priv.PublicKey = *pub
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return priv, nil
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case RSAMD5:
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fallthrough
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case RSASHA1:
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fallthrough
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case RSASHA1NSEC3SHA1:
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fallthrough
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case RSASHA256:
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fallthrough
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case RSASHA512:
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priv, err := readPrivateKeyRSA(m)
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if err != nil {
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return nil, err
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}
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pub := k.publicKeyRSA()
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if pub == nil {
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return nil, ErrKey
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}
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priv.PublicKey = *pub
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return priv, nil
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case ECCGOST:
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return nil, ErrPrivKey
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case ECDSAP256SHA256:
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fallthrough
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case ECDSAP384SHA384:
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priv, err := readPrivateKeyECDSA(m)
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if err != nil {
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return nil, err
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}
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pub := k.publicKeyECDSA()
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if pub == nil {
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return nil, ErrKey
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}
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priv.PublicKey = *pub
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return priv, nil
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case ED25519:
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return readPrivateKeyED25519(m)
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default:
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return nil, ErrPrivKey
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}
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}
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// Read a private key (file) string and create a public key. Return the private key.
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func readPrivateKeyRSA(m map[string]string) (*rsa.PrivateKey, error) {
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p := new(rsa.PrivateKey)
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p.Primes = []*big.Int{nil, nil}
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for k, v := range m {
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switch k {
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case "modulus", "publicexponent", "privateexponent", "prime1", "prime2":
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v1, err := fromBase64([]byte(v))
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if err != nil {
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return nil, err
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}
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switch k {
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case "modulus":
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p.PublicKey.N = big.NewInt(0)
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p.PublicKey.N.SetBytes(v1)
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case "publicexponent":
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i := big.NewInt(0)
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i.SetBytes(v1)
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p.PublicKey.E = int(i.Int64()) // int64 should be large enough
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case "privateexponent":
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p.D = big.NewInt(0)
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p.D.SetBytes(v1)
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case "prime1":
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p.Primes[0] = big.NewInt(0)
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p.Primes[0].SetBytes(v1)
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case "prime2":
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p.Primes[1] = big.NewInt(0)
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p.Primes[1].SetBytes(v1)
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}
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case "exponent1", "exponent2", "coefficient":
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// not used in Go (yet)
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case "created", "publish", "activate":
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// not used in Go (yet)
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}
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}
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return p, nil
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}
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func readPrivateKeyDSA(m map[string]string) (*dsa.PrivateKey, error) {
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p := new(dsa.PrivateKey)
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p.X = big.NewInt(0)
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for k, v := range m {
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switch k {
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case "private_value(x)":
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v1, err := fromBase64([]byte(v))
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if err != nil {
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return nil, err
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}
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p.X.SetBytes(v1)
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case "created", "publish", "activate":
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/* not used in Go (yet) */
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}
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}
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return p, nil
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}
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func readPrivateKeyECDSA(m map[string]string) (*ecdsa.PrivateKey, error) {
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p := new(ecdsa.PrivateKey)
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p.D = big.NewInt(0)
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// TODO: validate that the required flags are present
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for k, v := range m {
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switch k {
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case "privatekey":
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v1, err := fromBase64([]byte(v))
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if err != nil {
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return nil, err
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}
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p.D.SetBytes(v1)
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case "created", "publish", "activate":
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/* not used in Go (yet) */
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}
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}
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return p, nil
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}
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func readPrivateKeyED25519(m map[string]string) (ed25519.PrivateKey, error) {
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var p ed25519.PrivateKey
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// TODO: validate that the required flags are present
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for k, v := range m {
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switch k {
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case "privatekey":
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p1, err := fromBase64([]byte(v))
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if err != nil {
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return nil, err
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}
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if len(p1) != 32 {
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return nil, ErrPrivKey
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}
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// RFC 8080 and Golang's x/crypto/ed25519 differ as to how the
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// private keys are represented. RFC 8080 specifies that private
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// keys be stored solely as the seed value (p1 above) while the
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// ed25519 package represents them as the seed value concatenated
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// to the public key, which is derived from the seed value.
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//
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// ed25519.GenerateKey reads exactly 32 bytes from the passed in
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// io.Reader and uses them as the seed. It also derives the
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// public key and produces a compatible private key.
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_, p, err = ed25519.GenerateKey(bytes.NewReader(p1))
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if err != nil {
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return nil, err
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}
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case "created", "publish", "activate":
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/* not used in Go (yet) */
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}
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}
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return p, nil
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}
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// parseKey reads a private key from r. It returns a map[string]string,
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// with the key-value pairs, or an error when the file is not correct.
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func parseKey(r io.Reader, file string) (map[string]string, error) {
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s, cancel := scanInit(r)
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m := make(map[string]string)
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c := make(chan lex)
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k := ""
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defer func() {
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cancel()
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// zlexer can send up to two tokens, the next one and possibly 1 remainders.
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// Do a non-blocking read.
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_, ok := <-c
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_, ok = <-c
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if !ok {
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// too bad
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}
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}()
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// Start the lexer
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go klexer(s, c)
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for l := range c {
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// It should alternate
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switch l.value {
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case zKey:
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k = l.token
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case zValue:
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if k == "" {
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return nil, &ParseError{file, "no private key seen", l}
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}
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//println("Setting", strings.ToLower(k), "to", l.token, "b")
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m[strings.ToLower(k)] = l.token
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k = ""
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}
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}
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return m, nil
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}
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// klexer scans the sourcefile and returns tokens on the channel c.
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func klexer(s *scan, c chan lex) {
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var l lex
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str := "" // Hold the current read text
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commt := false
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key := true
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x, err := s.tokenText()
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defer close(c)
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for err == nil {
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l.column = s.position.Column
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l.line = s.position.Line
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switch x {
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case ':':
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if commt {
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break
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}
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l.token = str
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if key {
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l.value = zKey
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c <- l
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// Next token is a space, eat it
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s.tokenText()
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key = false
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str = ""
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} else {
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l.value = zValue
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}
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case ';':
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commt = true
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case '\n':
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if commt {
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// Reset a comment
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commt = false
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}
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l.value = zValue
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l.token = str
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c <- l
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str = ""
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commt = false
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key = true
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default:
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if commt {
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break
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}
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str += string(x)
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}
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x, err = s.tokenText()
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}
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if len(str) > 0 {
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// Send remainder
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l.token = str
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l.value = zValue
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c <- l
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}
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}
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