From 4468e3618313b9e250cfb05db5a45169b3385596 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Tue, 31 Mar 2020 06:24:43 -0700
Subject: [PATCH] wallet: add migration to regenerate missing change addresses.
 see #414, #413, #411.

---
 lib/wallet/wallet.js   |  6 ++++++
 lib/wallet/walletdb.js | 45 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/lib/wallet/wallet.js b/lib/wallet/wallet.js
index e6d0667b69..29994dc3a2 100644
--- a/lib/wallet/wallet.js
+++ b/lib/wallet/wallet.js
@@ -72,6 +72,7 @@ class Wallet extends EventEmitter {
     this.wid = 0;
     this.id = null;
     this.watchOnly = false;
+    this.fixedChange = false;
     this.accountDepth = 0;
     this.token = consensus.ZERO_HASH;
     this.tokenDepth = 0;
@@ -4456,6 +4457,7 @@ class Wallet extends EventEmitter {
       wid: this.wid,
       id: this.id,
       watchOnly: this.watchOnly,
+      fixedChange: this.fixedChange,
       accountDepth: this.accountDepth,
       token: this.token.toString('hex'),
       tokenDepth: this.tokenDepth,
@@ -4502,6 +4504,9 @@ class Wallet extends EventEmitter {
     if (this.watchOnly)
       flags |= 1;
 
+    if (this.fixedChange)
+      flags |= 2;
+
     bw.writeU8(flags);
     bw.writeU32(this.accountDepth);
     bw.writeBytes(this.token);
@@ -4523,6 +4528,7 @@ class Wallet extends EventEmitter {
     const flags = br.readU8();
 
     this.watchOnly = (flags & 1) !== 0;
+    this.fixedChange = (flags & 2) !== 0;
     this.accountDepth = br.readU32();
     this.token = br.readBytes(32);
     this.tokenDepth = br.readU32();
diff --git a/lib/wallet/walletdb.js b/lib/wallet/walletdb.js
index 746ff86799..e9af3939ad 100644
--- a/lib/wallet/walletdb.js
+++ b/lib/wallet/walletdb.js
@@ -802,6 +802,9 @@ class WalletDB extends EventEmitter {
 
     this.register(wallet);
 
+    if (!wallet.fixedChange)
+      await this._migrateChange(wallet);
+
     return wallet;
   }
 
@@ -1087,6 +1090,7 @@ class WalletDB extends EventEmitter {
     const wallet = Wallet.fromOptions(this, options);
 
     wallet.wid = this.depth;
+    wallet.fixedChange = true;
 
     await wallet.init(options, options.passphrase);
 
@@ -2270,6 +2274,47 @@ class WalletDB extends EventEmitter {
 
     return this.rollback(entry.height);
   }
+
+  /**
+   * Run change address migration.
+   * @param {Wallet} wallet
+   */
+
+  async _migrateChange(wallet) {
+    const b = this.db.batch();
+
+    this.logger.info('Regenerating change addresses.');
+
+    let total = 0;
+
+    for (let i = 0; i < wallet.accountDepth; i++) {
+      const account = await wallet.getAccount(i);
+
+      for (let i = 0; i < account.changeDepth + account.lookahead; i++) {
+        const key = account.deriveChange(i);
+        const path = key.toPath();
+
+        if (!await this.hasPath(account.wid, path.hash)) {
+          await this.savePath(b, account.wid, path);
+          total += 1;
+        }
+      }
+    }
+
+    wallet.fixedChange = true;
+
+    this.save(b, wallet);
+
+    await b.write();
+
+    if (total > 0) {
+      this.logger.warning('Regenerated %d change addresses.', total);
+      this.logger.warning(
+        'Please rescan if you believe you have missing outputs.');
+    } else {
+      this.logger.info('All change addresses present.');
+    }
+  }
 }
 
 /**