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package tun
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import (
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	"crypto/sha256"
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	"encoding/base64"
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	"encoding/hex"
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	"fmt"
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	"strings"
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)
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const DelegationTokenPrefix = "tg1_"
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const DelegationRecordVersion = 1
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const MaxDelegationsPerOwner = 128
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func EncodeDelegationToken(secret [32]byte) string {
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	return DelegationTokenPrefix + base64.RawURLEncoding.EncodeToString(secret[:])
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}
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func ParseDelegationToken(token string) (secret [32]byte, err error) {
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	if len(token) != 47 || !strings.HasPrefix(token, DelegationTokenPrefix) {
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		return secret, fmt.Errorf("invalid delegation token")
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	}
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	raw, err := base64.RawURLEncoding.Strict().DecodeString(token[4:])
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	if err != nil || len(raw) != len(secret) {
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		return secret, fmt.Errorf("invalid delegation token")
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	}
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	copy(secret[:], raw)
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	return secret, nil
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}
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func DelegationID(secret [32]byte) string {
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	digest := sha256.Sum256(secret[:])
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	return hex.EncodeToString(digest[:])
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}
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func IsDelegationID(id string) bool { return len(id) == 64 && lowerHex(id) }