secret/internal/secret/secret.go

package secret

import (
	"errors"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"strings"

	"filippo.io/age"
	"github.com/awnumar/memguard"
	"github.com/spf13/afero"
)

var (
	errGetEncryptedDataDeprecated = errors.New(
		"GetEncryptedData is deprecated - use version-specific methods")
	errGetCurrentVaultNotRegistered = errors.New(
		"GetCurrentVault function not registered")
)

// VaultInterface defines the interface that vault implementations must satisfy
type VaultInterface interface {
	GetDirectory() (string, error)
	AddSecret(name string, value *memguard.LockedBuffer, force bool) error
	GetName() string
	GetFilesystem() afero.Fs
	GetCurrentUnlocker() (Unlocker, error)
	GetOrDeriveLongTermKey() (*age.X25519Identity, error)
	// SetMnemonic and SetUnlockPassphrase give GetOrDeriveLongTermKey the
	// mnemonic to derive the long-term key from, and the passphrase for a
	// current passphrase unlocker; nil for none.
	SetMnemonic(mnemonic *memguard.LockedBuffer)
	SetUnlockPassphrase(passphrase *memguard.LockedBuffer)
	CreatePassphraseUnlocker(
		passphrase *memguard.LockedBuffer) (*PassphraseUnlocker, error)
}

// Secret represents a secret in a vault
type Secret struct {
	Name      string
	Directory string
	Metadata  Metadata
	vault     VaultInterface
}

// NewSecret creates a new Secret instance
func NewSecret(vault VaultInterface, name string) *Secret {
	DebugWith("Creating new secret instance",
		slog.String("secret_name", name),
		slog.String("vault_name", vault.GetName()),
	)

	// Convert slashes to percent signs for storage directory name
	storageName := strings.ReplaceAll(name, "/", "%")
	vaultDir, _ := vault.GetDirectory()
	secretDir := filepath.Join(vaultDir, "secrets.d", storageName)

	DebugWith("Secret storage details",
		slog.String("secret_name", name),
		slog.String("storage_name", storageName),
		slog.String("secret_dir", secretDir),
	)

	return &Secret{
		Name:      name,
		Directory: secretDir,
		vault:     vault,
	}
}

// LoadMetadata sets the secret's times from the modification times of its
// files, which can be read without unlocking the vault. UpdatedAt is when
// the secret's current file was last written, by an add or a promote.
// CreatedAt is when its oldest version's value.age was written. That file
// is never rewritten; the version's directory is no use, as its time
// changes when the next add rewrites the version's metadata.age.
func (s *Secret) LoadMetadata() error {
	fs := s.vault.GetFilesystem()

	current, err := fs.Stat(filepath.Join(s.Directory, "current"))
	if err != nil {
		return fmt.Errorf("failed to read when secret %s was updated: %w",
			s.Name, err)
	}

	versions, err := ListVersions(fs, s.Directory)
	if err != nil {
		return err
	}

	if len(versions) == 0 {
		return fmt.Errorf("secret %s has no versions: %w", s.Name, os.ErrNotExist)
	}

	// ListVersions lists the newest version first
	oldest := versions[len(versions)-1]

	value, err := fs.Stat(
		filepath.Join(s.Directory, "versions", oldest, "value.age"))
	if err != nil {
		return fmt.Errorf("failed to read when secret %s was created: %w",
			s.Name, err)
	}

	s.Metadata = Metadata{
		CreatedAt: value.ModTime(),
		UpdatedAt: current.ModTime(),
	}

	return nil
}

// GetMetadata returns the times LoadMetadata read
func (s *Secret) GetMetadata() Metadata {
	return s.Metadata
}

// GetEncryptedData is deprecated - data is now stored in versions
func (s *Secret) GetEncryptedData() ([]byte, error) {
	Debug("GetEncryptedData called but is deprecated in versioned model",
		"secret_name", s.Name)

	return nil, errGetEncryptedDataDeprecated
}

// Exists checks if the secret exists on disk
func (s *Secret) Exists() (bool, error) {
	DebugWith("Checking if secret exists",
		slog.String("secret_name", s.Name),
		slog.String("vault_name", s.vault.GetName()),
	)

	// Check if the secret directory exists and has a current symlink
	exists, err := afero.DirExists(s.vault.GetFilesystem(), s.Directory)
	if err != nil {
		Debug("Failed to check secret directory existence",
			"error", err, "secret_dir", s.Directory)

		return false, err
	}

	if !exists {
		Debug("Secret directory does not exist", "secret_dir", s.Directory)

		return false, nil
	}

	// Check if current symlink exists
	_, err = GetCurrentVersion(s.vault.GetFilesystem(), s.Directory)
	if err != nil {
		Debug("No current version found", "error", err, "secret_name", s.Name)

		return false, nil
	}

	DebugWith("Secret existence check result",
		slog.String("secret_name", s.Name),
		slog.Bool("exists", true),
	)

	return true, nil
}

// GetCurrentVault gets the current vault from the file system
// This function is a wrapper around the actual implementation in the vault package
// and exists to break the import cycle.
//
//nolint:ireturn // must return the interface to break the import cycle
func GetCurrentVault(fs afero.Fs, stateDir string) (VaultInterface, error) {
	// This is a forward declaration. The actual implementation is provided
	// by the vault package when it calls RegisterGetCurrentVaultFunc.
	if getCurrentVaultFunc == nil {
		return nil, errGetCurrentVaultNotRegistered
	}

	return getCurrentVaultFunc(fs, stateDir)
}

// getCurrentVaultFunc is a function variable that will be set by the vault package
// to implement the actual GetCurrentVault functionality
//
//nolint:gochecknoglobals // Required to break import cycle
var getCurrentVaultFunc func(fs afero.Fs, stateDir string) (VaultInterface, error)

// RegisterGetCurrentVaultFunc allows the vault package to register its
// implementation of GetCurrentVault to break the import cycle
func RegisterGetCurrentVaultFunc(
	fn func(fs afero.Fs, stateDir string) (VaultInterface, error),
) {
	getCurrentVaultFunc = fn
}