From 432ba9e5434da90d2cf680f23e8c7b7164c9f945 Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101-github@achow101.com>
Date: Mon, 1 Mar 2021 16:25:36 -0500
Subject: wallet: Store last hardened xpub cache

---
 src/wallet/walletdb.cpp | 24 ++++++++++++++++++++++++
 src/wallet/walletdb.h   |  1 +
 2 files changed, 25 insertions(+)

diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index 294fa3b8ee..72b987d327 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -52,6 +52,7 @@ const std::string TX{"tx"};
 const std::string VERSION{"version"};
 const std::string WALLETDESCRIPTOR{"walletdescriptor"};
 const std::string WALLETDESCRIPTORCACHE{"walletdescriptorcache"};
+const std::string WALLETDESCRIPTORLHCACHE{"walletdescriptorlhcache"};
 const std::string WALLETDESCRIPTORCKEY{"walletdescriptorckey"};
 const std::string WALLETDESCRIPTORKEY{"walletdescriptorkey"};
 const std::string WATCHMETA{"watchmeta"};
@@ -248,6 +249,13 @@ bool WalletBatch::WriteDescriptorParentCache(const CExtPubKey& xpub, const uint2
     return WriteIC(std::make_pair(std::make_pair(DBKeys::WALLETDESCRIPTORCACHE, desc_id), key_exp_index), ser_xpub);
 }
 
+bool WalletBatch::WriteDescriptorLastHardenedCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index)
+{
+    std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
+    xpub.Encode(ser_xpub.data());
+    return WriteIC(std::make_pair(std::make_pair(DBKeys::WALLETDESCRIPTORLHCACHE, desc_id), key_exp_index), ser_xpub);
+}
+
 bool WalletBatch::WriteDescriptorCacheItems(const uint256& desc_id, const DescriptorCache& cache)
 {
     for (const auto& parent_xpub_pair : cache.GetCachedParentExtPubKeys()) {
@@ -262,6 +270,11 @@ bool WalletBatch::WriteDescriptorCacheItems(const uint256& desc_id, const Descri
             }
         }
     }
+    for (const auto& lh_xpub_pair : cache.GetCachedLastHardenedExtPubKeys()) {
+        if (!WriteDescriptorLastHardenedCache(lh_xpub_pair.second, desc_id, lh_xpub_pair.first)) {
+            return false;
+        }
+    }
     return true;
 }
 
@@ -619,6 +632,17 @@ ReadKeyValue(CWallet* pwallet, CDataStream& ssKey, CDataStream& ssValue,
             } else {
                 wss.m_descriptor_caches[desc_id].CacheDerivedExtPubKey(key_exp_index, der_index, xpub);
             }
+        } else if (strType == DBKeys::WALLETDESCRIPTORLHCACHE) {
+            uint256 desc_id;
+            uint32_t key_exp_index;
+            ssKey >> desc_id;
+            ssKey >> key_exp_index;
+
+            std::vector<unsigned char> ser_xpub(BIP32_EXTKEY_SIZE);
+            ssValue >> ser_xpub;
+            CExtPubKey xpub;
+            xpub.Decode(ser_xpub.data());
+            wss.m_descriptor_caches[desc_id].CacheLastHardenedExtPubKey(key_exp_index, xpub);
         } else if (strType == DBKeys::WALLETDESCRIPTORKEY) {
             uint256 desc_id;
             CPubKey pubkey;
diff --git a/src/wallet/walletdb.h b/src/wallet/walletdb.h
index b11d750a3a..e7c6b61891 100644
--- a/src/wallet/walletdb.h
+++ b/src/wallet/walletdb.h
@@ -246,6 +246,7 @@ public:
     bool WriteDescriptor(const uint256& desc_id, const WalletDescriptor& descriptor);
     bool WriteDescriptorDerivedCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index, uint32_t der_index);
     bool WriteDescriptorParentCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index);
+    bool WriteDescriptorLastHardenedCache(const CExtPubKey& xpub, const uint256& desc_id, uint32_t key_exp_index);
     bool WriteDescriptorCacheItems(const uint256& desc_id, const DescriptorCache& cache);
 
     /// Write destination data key,value tuple to database
-- 
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