indexeddb: migrate name and format of backup_version

The name was stupid, and this was the only string that was stored in the legacy
format; we can fix both problems with a cheeky migration.

crates/matrix-sdk-indexeddb/src/crypto_store/migrations/mod.rs

@@ -25,6 +25,7 @@ use crate::{
 
 mod old_keys;
 mod v0_to_v5;
+mod v10_to_v11;
 mod v5_to_v7;
 mod v7;
 mod v7_to_v8;
@@ -106,8 +107,12 @@ pub async fn open_and_upgrade_db(
         v8_to_v10::schema_delete(name).await?;
     }
 
+    if old_version < 11 {
+        v10_to_v11::data_migrate(name, serializer).await?;
+    }
+
     // Open and return the DB (we know it's at the latest version)
-    Ok(IdbDatabase::open_u32(name, 10)?.await?)
+    Ok(IdbDatabase::open_u32(name, 11)?.await?)
 }
 
 async fn db_version(name: &str) -> Result<u32, IndexeddbCryptoStoreError> {
@@ -183,7 +188,10 @@ mod tests {
 
     use super::{v0_to_v5, v7::InboundGroupSessionIndexedDbObject2};
     use crate::{
-        crypto_store::{keys, migrations::*, InboundGroupSessionIndexedDbObject},
+        crypto_store::{
+            indexeddb_serializer::MaybeEncrypted, keys, migrations::*,
+            InboundGroupSessionIndexedDbObject,
+        },
         IndexeddbCryptoStore,
     };
 

crates/matrix-sdk-indexeddb/src/crypto_store/migrations/old_keys.rs

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#[cfg(doc)]
+use crate::crypto_store::keys::BACKUP_VERSION_V1;
+
 /// Old format of the `inbound_group_sessions` store which lacked indexes or
 /// a sensible structure
 pub const INBOUND_GROUP_SESSIONS_V1: &str = "inbound_group_sessions";
@@ -20,3 +23,6 @@ pub const INBOUND_GROUP_SESSIONS_V1: &str = "inbound_group_sessions";
 /// JSON-encoding and arrays of ints instead of base64.
 /// Also lacked the `backed_up_to` property+index.
 pub const INBOUND_GROUP_SESSIONS_V2: &str = "inbound_group_sessions2";
+
+/// An old name for [`BACKUP_VERSION_V1`].
+pub const BACKUP_KEY_V1: &str = "backup_key_v1";

crates/matrix-sdk-indexeddb/src/crypto_store/migrations/v10_to_v11.rs

@@ -0,0 +1,54 @@
+// Copyright 2024 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Migration code that moves from `backup_keys.backup_key_v1` to
+//! `backup_keys.backup_version_v1`, switching to a new serialization format.
+
+use indexed_db_futures::IdbQuerySource;
+use wasm_bindgen::JsValue;
+use web_sys::IdbTransactionMode;
+
+use crate::crypto_store::{
+    indexeddb_serializer::IndexeddbSerializer,
+    keys,
+    migrations::{old_keys, MigrationDb},
+};
+
+/// Migrate data from `backup_keys.backup_key_v1` to
+/// `backup_keys.backup_version_v1`.
+pub(crate) async fn data_migrate(
+    name: &str,
+    serializer: &IndexeddbSerializer,
+) -> crate::crypto_store::Result<()> {
+    let db = MigrationDb::new(name, 11).await?;
+    let txn = db.transaction_on_one_with_mode(keys::BACKUP_KEYS, IdbTransactionMode::Readwrite)?;
+    let store = txn.object_store(keys::BACKUP_KEYS)?;
+
+    let bv = store.get(&JsValue::from_str(old_keys::BACKUP_KEY_V1))?.await?;
+
+    let Some(bv) = bv else {
+        return Ok(());
+    };
+
+    // backup_key_v1 was only ever serialized with the legacy format. Also, it's a
+    // string, so if we use `deserialize_value` on it, it will be incorrectly
+    // handled as a new-format object.
+    let bv: String = serializer.deserialize_legacy_value(bv)?;
+
+    // Re-serialize as new format, then store in the new field.
+    let serialized = serializer.serialize_value(&bv)?;
+    store.put_key_val(&JsValue::from_str(keys::BACKUP_VERSION_V1), &serialized)?.await?;
+    store.delete(&JsValue::from_str(old_keys::BACKUP_KEY_V1))?.await?;
+    Ok(())
+}

crates/matrix-sdk-indexeddb/src/crypto_store/mod.rs

@@ -90,7 +90,11 @@ mod keys {
 
     // backup v1
     pub const BACKUP_KEYS: &str = "backup_keys";
-    pub const BACKUP_KEY_V1: &str = "backup_key_v1";
+
+    /// Indexeddb key for the key backup version that [`RECOVERY_KEY_V1`]
+    /// corresponds to.
+    pub const BACKUP_VERSION_V1: &str = "backup_version_v1";
+
     /// Indexeddb key for the backup decryption key.
     ///
     /// Known, for historical reasons, as the recovery key. Not to be confused
@@ -479,9 +483,10 @@ impl IndexeddbCryptoStore {
         }
 
         if let Some(a) = &backup_version {
-            indexeddb_changes
-                .get(keys::BACKUP_KEYS)
-                .put(JsValue::from_str(keys::BACKUP_KEY_V1), self.serializer.serialize_value(&a)?);
+            indexeddb_changes.get(keys::BACKUP_KEYS).put(
+                JsValue::from_str(keys::BACKUP_VERSION_V1),
+                self.serializer.serialize_value(&a)?,
+            );
         }
 
         if !changes.sessions.is_empty() {
@@ -1208,7 +1213,7 @@ impl_crypto_store! {
             let store = tx.object_store(keys::BACKUP_KEYS)?;
 
             let backup_version = store
-                .get(&JsValue::from_str(keys::BACKUP_KEY_V1))?
+                .get(&JsValue::from_str(keys::BACKUP_VERSION_V1))?
                 .await?
                 .map(|i| self.serializer.deserialize_value(i))
                 .transpose()?;