40 lines
1.2 KiB
Go
40 lines
1.2 KiB
Go
package webui
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import (
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"crypto/rand"
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"fmt"
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"os"
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"path/filepath"
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)
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const appSecretSize = 32
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// LoadOrCreateAppSecret reads the app's CSRF-signing secret from path, generating a
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// fresh random one on first run if the file doesn't exist yet — mirrors
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// mailstore.LoadOrCreateMasterKey's identical generate-if-missing pattern for the
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// mailstore encryption key. Unlike that key, losing this one has no data-loss
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// consequence: every outstanding CSRF token just stops validating, so users get
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// logged-out-feeling form-submit errors until they reload a page for a fresh one.
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func LoadOrCreateAppSecret(path string) ([]byte, error) {
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if b, err := os.ReadFile(path); err == nil {
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if len(b) != appSecretSize {
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return nil, fmt.Errorf("app secret at %s is %d bytes, want %d", path, len(b), appSecretSize)
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}
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return b, nil
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} else if !os.IsNotExist(err) {
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return nil, err
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}
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if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
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return nil, err
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}
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secret := make([]byte, appSecretSize)
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if _, err := rand.Read(secret); err != nil {
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return nil, err
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}
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if err := os.WriteFile(path, secret, 0o600); err != nil {
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return nil, err
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}
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return secret, nil
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}
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