fix(pin): keep pin if unchanged

Signed-off-by: fufesou <linlong1266@gmail.com>

src/config.rs

@@ -521,8 +521,9 @@ impl Config2 {
                 encrypt_str_or_original(&socks.password, PASSWORD_ENC_VERSION, ENCRYPT_MAX_LEN);
             config.socks = Some(socks);
         }
+        let stored = Config::load_::<Config2>("2");
         config.unlock_pin =
-            encrypt_str_or_original(&config.unlock_pin, PASSWORD_ENC_VERSION, ENCRYPT_MAX_LEN);
+            keep_encrypted_storage_if_plaintext_unchanged(&config.unlock_pin, &stored.unlock_pin);
         Config::store_(&config, "2");
     }
 
@@ -541,6 +542,14 @@ impl Config2 {
     }
 }
 
+fn keep_encrypted_storage_if_plaintext_unchanged(plain: &str, stored: &str) -> String {
+    let (stored_plain, encrypted, _) = decrypt_str_or_original(stored, PASSWORD_ENC_VERSION);
+    if encrypted && stored_plain == plain {
+        return stored.to_owned();
+    }
+    encrypt_str_or_original(plain, PASSWORD_ENC_VERSION, ENCRYPT_MAX_LEN)
+}
+
 pub fn load_path<T: serde::Serialize + serde::de::DeserializeOwned + Default + std::fmt::Debug>(
     file: PathBuf,
 ) -> T {
@@ -3503,8 +3512,7 @@ mod tests {
             assert!(Config::set(cfg));
 
             let stored = Config::load().enc_id;
-            let (stored_id, encrypted, _) =
-                decrypt_str_or_original(&stored, PASSWORD_ENC_VERSION);
+            let (stored_id, encrypted, _) = decrypt_str_or_original(&stored, PASSWORD_ENC_VERSION);
             assert_ne!(stored, original_enc_id);
             assert!(encrypted);
             assert_eq!(stored_id, updated_id);
@@ -3512,6 +3520,28 @@ mod tests {
         });
     }
 
+    #[test]
+    fn test_config2_store_keeps_existing_unlock_pin_when_pin_is_unchanged() {
+        let pin = "123456";
+        let original_unlock_pin =
+            encrypt_str_or_original(pin, PASSWORD_ENC_VERSION, ENCRYPT_MAX_LEN);
+        let mut cfg = Config2 {
+            unlock_pin: original_unlock_pin.clone(),
+            ..Default::default()
+        };
+        Config::store_(&cfg, "2");
+        let (unlock_pin, decrypted, _) =
+            decrypt_str_or_original(&cfg.unlock_pin, PASSWORD_ENC_VERSION);
+        assert!(decrypted);
+        cfg.unlock_pin = unlock_pin;
+        cfg.nat_type = 1;
+
+        cfg.store();
+
+        let stored = Config::load_::<Config2>("2");
+        assert_eq!(stored.unlock_pin, original_unlock_pin);
+    }
+
     #[test]
     fn test_set_does_not_convert_plaintext_permanent_password_to_storage_format_in_memory() {
         let mut cfg = Config::default();