76 lines
1.6 KiB
Go
76 lines
1.6 KiB
Go
package agentkey
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import (
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"crypto/rand"
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"encoding/hex"
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"fmt"
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"os"
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"path/filepath"
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"strings"
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)
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const (
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fileName = "agent.key"
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keyBytes = 32
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keyLen = keyBytes * 2
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)
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func LoadOrCreate(stateDir string) (string, error) {
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if err := os.MkdirAll(stateDir, 0o700); err != nil {
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return "", err
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}
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if err := os.Chmod(stateDir, 0o700); err != nil {
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return "", err
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}
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path := filepath.Join(stateDir, fileName)
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if info, err := os.Stat(path); err == nil {
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if !info.Mode().IsRegular() {
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return "", fmt.Errorf("agent key is not a regular file: %s", path)
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}
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if info.Mode().Perm() != 0o600 {
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if err := os.Chmod(path, 0o600); err != nil {
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return "", err
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}
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}
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b, err := os.ReadFile(path)
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if err != nil {
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return "", err
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}
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return validate(strings.TrimSpace(string(b)), path)
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} else if !os.IsNotExist(err) {
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return "", err
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}
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key, err := generate()
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if err != nil {
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return "", err
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}
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tmp := fmt.Sprintf("%s.%d.tmp", path, os.Getpid())
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defer os.Remove(tmp)
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if err := os.WriteFile(tmp, []byte(key+"\n"), 0o600); err != nil {
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return "", err
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}
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if err := os.Rename(tmp, path); err != nil {
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return "", err
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}
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return key, nil
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}
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func validate(key string, path string) (string, error) {
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if len(key) != keyLen {
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return "", fmt.Errorf("invalid agent key in %s", path)
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}
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if _, err := hex.DecodeString(key); err != nil {
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return "", fmt.Errorf("invalid agent key in %s", path)
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}
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return strings.ToLower(key), nil
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}
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func generate() (string, error) {
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var b [keyBytes]byte
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if _, err := rand.Read(b[:]); err != nil {
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return "", err
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}
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return hex.EncodeToString(b[:]), nil
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}
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