package dns
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import (
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"bufio"
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"crypto"
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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 RSAMD5, DSA, DSANSEC3SHA1:
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return nil, ErrAlg
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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 = new(big.Int).SetBytes(v1)
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case "publicexponent":
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i := new(big.Int).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 = new(big.Int).SetBytes(v1)
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case "prime1":
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p.Primes[0] = new(big.Int).SetBytes(v1)
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case "prime2":
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p.Primes[1] = new(big.Int).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 readPrivateKeyECDSA(m map[string]string) (*ecdsa.PrivateKey, error) {
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p := new(ecdsa.PrivateKey)
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p.D = new(big.Int)
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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) != ed25519.SeedSize {
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return nil, ErrPrivKey
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}
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p = ed25519.NewKeyFromSeed(p1)
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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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m := make(map[string]string)
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var k string
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c := newKLexer(r)
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for l, ok := c.Next(); ok; l, ok = c.Next() {
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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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m[strings.ToLower(k)] = l.token
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k = ""
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}
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}
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// Surface any read errors from r.
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if err := c.Err(); err != nil {
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return nil, &ParseError{file: file, err: err.Error()}
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}
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return m, nil
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}
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type klexer struct {
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br io.ByteReader
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readErr error
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line int
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column int
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key bool
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eol bool // end-of-line
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}
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func newKLexer(r io.Reader) *klexer {
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br, ok := r.(io.ByteReader)
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if !ok {
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br = bufio.NewReaderSize(r, 1024)
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}
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return &klexer{
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br: br,
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line: 1,
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key: true,
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}
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}
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func (kl *klexer) Err() error {
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if kl.readErr == io.EOF {
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return nil
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}
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return kl.readErr
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}
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// readByte returns the next byte from the input
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func (kl *klexer) readByte() (byte, bool) {
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if kl.readErr != nil {
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return 0, false
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}
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c, err := kl.br.ReadByte()
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if err != nil {
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kl.readErr = err
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return 0, false
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}
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// delay the newline handling until the next token is delivered,
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// fixes off-by-one errors when reporting a parse error.
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if kl.eol {
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kl.line++
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kl.column = 0
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kl.eol = false
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}
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if c == '\n' {
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kl.eol = true
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} else {
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kl.column++
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}
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return c, true
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}
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func (kl *klexer) Next() (lex, bool) {
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var (
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l lex
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str strings.Builder
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commt bool
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)
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for x, ok := kl.readByte(); ok; x, ok = kl.readByte() {
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l.line, l.column = kl.line, kl.column
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switch x {
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case ':':
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if commt || !kl.key {
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break
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}
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kl.key = false
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// Next token is a space, eat it
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kl.readByte()
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l.value = zKey
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l.token = str.String()
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return l, true
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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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if kl.key && str.Len() == 0 {
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// ignore empty lines
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break
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}
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kl.key = true
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l.value = zValue
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l.token = str.String()
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return l, 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.WriteByte(x)
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}
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}
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if kl.readErr != nil && kl.readErr != io.EOF {
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// Don't return any tokens after a read error occurs.
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return lex{value: zEOF}, false
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}
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if str.Len() > 0 {
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// Send remainder
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l.value = zValue
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l.token = str.String()
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return l, true
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}
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return lex{value: zEOF}, false
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}
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