Convert CWallet::ScanForWalletTransactions and SyncTransaction to the new Chain apis

Only change in behavior is "Rescan started from block <height>" message
replaced by "Rescan started from block <hash>" message in
ScanForWalletTransactions.

Co-authored-by: Ben Woosley <ben.woosley@gmail.com>

7 files changed, 209 insertions, 125 deletions

diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index 6e2224bc3e..1f39e650dc 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -60,6 +60,42 @@ class LockImpl : public Chain::Lock
         assert(block != nullptr);
         return block->GetMedianTimePast();
     }
+    Optional<int> findFirstBlockWithTime(int64_t time, uint256* hash) override
+    {
+        CBlockIndex* block = ::chainActive.FindEarliestAtLeast(time);
+        if (block) {
+            if (hash) *hash = block->GetBlockHash();
+            return block->nHeight;
+        }
+        return nullopt;
+    }
+    Optional<int> findFirstBlockWithTimeAndHeight(int64_t time, int height) override
+    {
+        // TODO: Could update CChain::FindEarliestAtLeast() to take a height
+        // parameter and use it with std::lower_bound() to make this
+        // implementation more efficient and allow combining
+        // findFirstBlockWithTime and findFirstBlockWithTimeAndHeight into one
+        // method.
+        for (CBlockIndex* block = ::chainActive[height]; block; block = ::chainActive.Next(block)) {
+            if (block->GetBlockTime() >= time) {
+                return block->nHeight;
+            }
+        }
+        return nullopt;
+    }
+    Optional<int> findPruned(int start_height, Optional<int> stop_height) override
+    {
+        if (::fPruneMode) {
+            CBlockIndex* block = stop_height ? ::chainActive[*stop_height] : ::chainActive.Tip();
+            while (block && block->nHeight >= start_height) {
+                if ((block->nStatus & BLOCK_HAVE_DATA) == 0) {
+                    return block->nHeight;
+                }
+                block = block->pprev;
+            }
+        }
+        return nullopt;
+    }
     Optional<int> findFork(const uint256& hash, Optional<int>* height) override
     {
         const CBlockIndex* block = LookupBlockIndex(hash);
@@ -116,6 +152,11 @@ public:
         }
         return true;
     }
+    double guessVerificationProgress(const uint256& block_hash) override
+    {
+        LOCK(cs_main);
+        return GuessVerificationProgress(Params().TxData(), LookupBlockIndex(block_hash));
+    }
 };
 
 } // namespace
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 8c7bd8c6ea..aef81675e0 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -58,6 +58,26 @@ public:
         //! will abort.
         virtual int64_t getBlockMedianTimePast(int height) = 0;
 
+        //! Return height of the first block in the chain with timestamp equal
+        //! or greater than the given time, or nullopt if there is no block with
+        //! a high enough timestamp. Also return the block hash as an optional
+        //! output parameter (to avoid the cost of a second lookup in case this
+        //! information is needed.)
+        virtual Optional<int> findFirstBlockWithTime(int64_t time, uint256* hash) = 0;
+
+        //! Return height of the first block in the chain with timestamp equal
+        //! or greater than the given time and height equal or greater than the
+        //! given height, or nullopt if there is no such block.
+        //!
+        //! Calling this with height 0 is equivalent to calling
+        //! findFirstBlockWithTime, but less efficient because it requires a
+        //! linear instead of a binary search.
+        virtual Optional<int> findFirstBlockWithTimeAndHeight(int64_t time, int height) = 0;
+
+        //! Return height of last block in the specified range which is pruned, or
+        //! nullopt if no block in the range is pruned. Range is inclusive.
+        virtual Optional<int> findPruned(int start_height = 0, Optional<int> stop_height = nullopt) = 0;
+
         //! Return height of the highest block on the chain that is an ancestor
         //! of the specified block, or nullopt if no common ancestor is found.
         //! Also return the height of the specified block as an optional output
@@ -85,6 +105,10 @@ public:
         CBlock* block = nullptr,
         int64_t* time = nullptr,
         int64_t* max_time = nullptr) = 0;
+
+    //! Estimate fraction of total transactions verified if blocks up to
+    //! the specified block hash are verified.
+    virtual double guessVerificationProgress(const uint256& block_hash) = 0;
 };
 
 //! Interface to let node manage chain clients (wallets, or maybe tools for
diff --git a/src/qt/test/wallettests.cpp b/src/qt/test/wallettests.cpp
index 610d83acb6..ee84da0cdf 100644
--- a/src/qt/test/wallettests.cpp
+++ b/src/qt/test/wallettests.cpp
@@ -1,6 +1,7 @@
 #include <qt/test/wallettests.h>
 #include <qt/test/util.h>
 
+#include <init.h>
 #include <interfaces/chain.h>
 #include <interfaces/node.h>
 #include <base58.h>
@@ -146,13 +147,10 @@ void TestGUI()
         auto locked_chain = wallet->chain().lock();
         WalletRescanReserver reserver(wallet.get());
         reserver.reserve();
-        const CBlockIndex* const null_block = nullptr;
-        const CBlockIndex *stop_block, *failed_block;
-        QCOMPARE(
-            wallet->ScanForWalletTransactions(chainActive.Genesis(), nullptr, reserver, failed_block, stop_block, true /* fUpdate */),
-            CWallet::ScanResult::SUCCESS);
-        QCOMPARE(stop_block, chainActive.Tip());
-        QCOMPARE(failed_block, null_block);
+        CWallet::ScanResult result = wallet->ScanForWalletTransactions(locked_chain->getBlockHash(0), {} /* stop_block */, reserver, true /* fUpdate */);
+        QCOMPARE(result.status, CWallet::ScanResult::SUCCESS);
+        QCOMPARE(result.stop_block, chainActive.Tip()->GetBlockHash());
+        QVERIFY(result.failed_block.IsNull());
     }
     wallet->SetBroadcastTransactions(true);
 
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 298a674b07..32173a92d0 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -3387,50 +3387,48 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
     }
 
-    CBlockIndex *pindexStart = nullptr;
-    CBlockIndex *pindexStop = nullptr;
-    CBlockIndex *pChainTip = nullptr;
+    int start_height = 0;
+    uint256 start_block, stop_block;
     {
         auto locked_chain = pwallet->chain().lock();
-        pindexStart = chainActive.Genesis();
-        pChainTip = chainActive.Tip();
+        Optional<int> tip_height = locked_chain->getHeight();
 
         if (!request.params[0].isNull()) {
-            pindexStart = chainActive[request.params[0].get_int()];
-            if (!pindexStart) {
+            start_height = request.params[0].get_int();
+            if (start_height < 0 || !tip_height || start_height > *tip_height) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid start_height");
             }
         }
 
+        Optional<int> stop_height;
         if (!request.params[1].isNull()) {
-            pindexStop = chainActive[request.params[1].get_int()];
-            if (!pindexStop) {
+            stop_height = request.params[1].get_int();
+            if (*stop_height < 0 || !tip_height || *stop_height > *tip_height) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid stop_height");
             }
-            else if (pindexStop->nHeight < pindexStart->nHeight) {
+            else if (*stop_height < start_height) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, "stop_height must be greater than start_height");
             }
         }
-    }
 
-    // We can't rescan beyond non-pruned blocks, stop and throw an error
-    if (fPruneMode) {
-        auto locked_chain = pwallet->chain().lock();
-        CBlockIndex *block = pindexStop ? pindexStop : pChainTip;
-        while (block && block->nHeight >= pindexStart->nHeight) {
-            if (!(block->nStatus & BLOCK_HAVE_DATA)) {
-                throw JSONRPCError(RPC_MISC_ERROR, "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height.");
+        // We can't rescan beyond non-pruned blocks, stop and throw an error
+        if (locked_chain->findPruned(start_height, stop_height)) {
+            throw JSONRPCError(RPC_MISC_ERROR, "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height.");
+        }
+
+        if (tip_height) {
+            start_block = locked_chain->getBlockHash(start_height);
+            if (stop_height) {
+                stop_block = locked_chain->getBlockHash(*stop_height);
             }
-            block = block->pprev;
         }
     }
 
-    const CBlockIndex *failed_block, *stopBlock;
     CWallet::ScanResult result =
-        pwallet->ScanForWalletTransactions(pindexStart, pindexStop, reserver, failed_block, stopBlock, true);
-    switch (result) {
+        pwallet->ScanForWalletTransactions(start_block, stop_block, reserver, true /* fUpdate */);
+    switch (result.status) {
     case CWallet::ScanResult::SUCCESS:
-        break; // stopBlock set by ScanForWalletTransactions
+        break;
     case CWallet::ScanResult::FAILURE:
         throw JSONRPCError(RPC_MISC_ERROR, "Rescan failed. Potentially corrupted data files.");
     case CWallet::ScanResult::USER_ABORT:
@@ -3438,8 +3436,8 @@ UniValue rescanblockchain(const JSONRPCRequest& request)
         // no default case, so the compiler can warn about missing cases
     }
     UniValue response(UniValue::VOBJ);
-    response.pushKV("start_height", pindexStart->nHeight);
-    response.pushKV("stop_height", stopBlock->nHeight);
+    response.pushKV("start_height", start_height);
+    response.pushKV("stop_height", result.stop_height ? *result.stop_height : UniValue());
     return response;
 }
 
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 4377e9f29d..8c380f1257 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -39,7 +39,6 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
     auto chain = interfaces::MakeChain();
 
     // Cap last block file size, and mine new block in a new block file.
-    const CBlockIndex* const null_block = nullptr;
     CBlockIndex* oldTip = chainActive.Tip();
     GetBlockFileInfo(oldTip->GetBlockPos().nFile)->nSize = MAX_BLOCKFILE_SIZE;
     CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
@@ -53,10 +52,11 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
-        const CBlockIndex *stop_block = null_block + 1, *failed_block = null_block + 1;
-        BOOST_CHECK_EQUAL(wallet.ScanForWalletTransactions(nullptr, nullptr, reserver, failed_block, stop_block), CWallet::ScanResult::SUCCESS);
-        BOOST_CHECK_EQUAL(failed_block, null_block);
-        BOOST_CHECK_EQUAL(stop_block, null_block);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions({} /* start_block */, {} /* stop_block */, reserver, false /* update */);
+        BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::SUCCESS);
+        BOOST_CHECK(result.failed_block.IsNull());
+        BOOST_CHECK(result.stop_block.IsNull());
+        BOOST_CHECK(!result.stop_height);
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 0);
     }
 
@@ -67,10 +67,11 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
-        const CBlockIndex *stop_block = null_block + 1, *failed_block = null_block + 1;
-        BOOST_CHECK_EQUAL(wallet.ScanForWalletTransactions(oldTip, nullptr, reserver, failed_block, stop_block), CWallet::ScanResult::SUCCESS);
-        BOOST_CHECK_EQUAL(failed_block, null_block);
-        BOOST_CHECK_EQUAL(stop_block, newTip);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(oldTip->GetBlockHash(), {} /* stop_block */, reserver, false /* update */);
+        BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::SUCCESS);
+        BOOST_CHECK(result.failed_block.IsNull());
+        BOOST_CHECK_EQUAL(result.stop_block, newTip->GetBlockHash());
+        BOOST_CHECK_EQUAL(*result.stop_height, newTip->nHeight);
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 100 * COIN);
     }
 
@@ -85,10 +86,11 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
-        const CBlockIndex *stop_block = null_block + 1, *failed_block = null_block + 1;
-        BOOST_CHECK_EQUAL(wallet.ScanForWalletTransactions(oldTip, nullptr, reserver, failed_block, stop_block), CWallet::ScanResult::FAILURE);
-        BOOST_CHECK_EQUAL(failed_block, oldTip);
-        BOOST_CHECK_EQUAL(stop_block, newTip);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(oldTip->GetBlockHash(), {} /* stop_block */, reserver, false /* update */);
+        BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::FAILURE);
+        BOOST_CHECK_EQUAL(result.failed_block, oldTip->GetBlockHash());
+        BOOST_CHECK_EQUAL(result.stop_block, newTip->GetBlockHash());
+        BOOST_CHECK_EQUAL(*result.stop_height, newTip->nHeight);
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 50 * COIN);
     }
 
@@ -102,10 +104,11 @@ BOOST_FIXTURE_TEST_CASE(scan_for_wallet_transactions, TestChain100Setup)
         AddKey(wallet, coinbaseKey);
         WalletRescanReserver reserver(&wallet);
         reserver.reserve();
-        const CBlockIndex *stop_block = null_block + 1, *failed_block = null_block + 1;
-        BOOST_CHECK_EQUAL(wallet.ScanForWalletTransactions(oldTip, nullptr, reserver, failed_block, stop_block), CWallet::ScanResult::FAILURE);
-        BOOST_CHECK_EQUAL(failed_block, newTip);
-        BOOST_CHECK_EQUAL(stop_block, null_block);
+        CWallet::ScanResult result = wallet.ScanForWalletTransactions(oldTip->GetBlockHash(), {} /* stop_block */, reserver, false /* update */);
+        BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::FAILURE);
+        BOOST_CHECK_EQUAL(result.failed_block, newTip->GetBlockHash());
+        BOOST_CHECK(result.stop_block.IsNull());
+        BOOST_CHECK(!result.stop_height);
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 0);
     }
 }
@@ -340,11 +343,11 @@ public:
         AddKey(*wallet, coinbaseKey);
         WalletRescanReserver reserver(wallet.get());
         reserver.reserve();
-        const CBlockIndex* const null_block = nullptr;
-        const CBlockIndex *stop_block = null_block + 1, *failed_block = null_block + 1;
-        BOOST_CHECK_EQUAL(wallet->ScanForWalletTransactions(chainActive.Genesis(), nullptr, reserver, failed_block, stop_block), CWallet::ScanResult::SUCCESS);
-        BOOST_CHECK_EQUAL(stop_block, chainActive.Tip());
-        BOOST_CHECK_EQUAL(failed_block, null_block);
+        CWallet::ScanResult result = wallet->ScanForWalletTransactions(chainActive.Genesis()->GetBlockHash(), {} /* stop_block */, reserver, false /* update */);
+        BOOST_CHECK_EQUAL(result.status, CWallet::ScanResult::SUCCESS);
+        BOOST_CHECK_EQUAL(result.stop_block, chainActive.Tip()->GetBlockHash());
+        BOOST_CHECK_EQUAL(*result.stop_height, chainActive.Height());
+        BOOST_CHECK(result.failed_block.IsNull());
     }
 
     ~ListCoinsTestingSetup()
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 32275c6180..4b1d010fed 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1117,8 +1117,8 @@ void CWallet::MarkConflicted(const uint256& hashBlock, const uint256& hashTx)
     }
 }
 
-void CWallet::SyncTransaction(const CTransactionRef& ptx, const CBlockIndex *pindex, int posInBlock, bool update_tx) {
-    if (!AddToWalletIfInvolvingMe(ptx, pindex->GetBlockHash(), posInBlock, update_tx))
+void CWallet::SyncTransaction(const CTransactionRef& ptx, const uint256& block_hash, int posInBlock, bool update_tx) {
+    if (!AddToWalletIfInvolvingMe(ptx, block_hash, posInBlock, update_tx))
         return; // Not one of ours
 
     // If a transaction changes 'conflicted' state, that changes the balance
@@ -1130,7 +1130,7 @@ void CWallet::SyncTransaction(const CTransactionRef& ptx, const CBlockIndex *pin
 void CWallet::TransactionAddedToMempool(const CTransactionRef& ptx) {
     auto locked_chain = chain().lock();
     LOCK(cs_wallet);
-    SyncTransaction(ptx);
+    SyncTransaction(ptx, {} /* block hash */, 0 /* position in block */);
 
     auto it = mapWallet.find(ptx->GetHash());
     if (it != mapWallet.end()) {
@@ -1158,11 +1158,11 @@ void CWallet::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const
     // the notification that the conflicted transaction was evicted.
 
     for (const CTransactionRef& ptx : vtxConflicted) {
-        SyncTransaction(ptx);
+        SyncTransaction(ptx, {} /* block hash */, 0 /* position in block */);
         TransactionRemovedFromMempool(ptx);
     }
     for (size_t i = 0; i < pblock->vtx.size(); i++) {
-        SyncTransaction(pblock->vtx[i], pindex, i);
+        SyncTransaction(pblock->vtx[i], pindex->GetBlockHash(), i);
         TransactionRemovedFromMempool(pblock->vtx[i]);
     }
 
@@ -1174,7 +1174,7 @@ void CWallet::BlockDisconnected(const std::shared_ptr<const CBlock>& pblock) {
     LOCK(cs_wallet);
 
     for (const CTransactionRef& ptx : pblock->vtx) {
-        SyncTransaction(ptx);
+        SyncTransaction(ptx, {} /* block hash */, 0 /* position in block */);
     }
 }
 
@@ -1587,132 +1587,143 @@ int64_t CWallet::RescanFromTime(int64_t startTime, const WalletRescanReserver& r
     // Find starting block. May be null if nCreateTime is greater than the
     // highest blockchain timestamp, in which case there is nothing that needs
     // to be scanned.
-    CBlockIndex* startBlock = nullptr;
+    uint256 start_block;
     {
         auto locked_chain = chain().lock();
-        startBlock = chainActive.FindEarliestAtLeast(startTime - TIMESTAMP_WINDOW);
-        WalletLogPrintf("%s: Rescanning last %i blocks\n", __func__, startBlock ? chainActive.Height() - startBlock->nHeight + 1 : 0);
+        const Optional<int> start_height = locked_chain->findFirstBlockWithTime(startTime - TIMESTAMP_WINDOW, &start_block);
+        const Optional<int> tip_height = locked_chain->getHeight();
+        WalletLogPrintf("%s: Rescanning last %i blocks\n", __func__, tip_height && start_height ? *tip_height - *start_height + 1 : 0);
     }
 
-    if (startBlock) {
-        const CBlockIndex *failedBlock, *stop_block;
+    if (!start_block.IsNull()) {
         // TODO: this should take into account failure by ScanResult::USER_ABORT
-        if (ScanResult::FAILURE == ScanForWalletTransactions(startBlock, nullptr, reserver, failedBlock, stop_block, update)) {
-            return failedBlock->GetBlockTimeMax() + TIMESTAMP_WINDOW + 1;
+        ScanResult result = ScanForWalletTransactions(start_block, {} /* stop_block */, reserver, update);
+        if (result.status == ScanResult::FAILURE) {
+            int64_t time_max;
+            if (!chain().findBlock(result.failed_block, nullptr /* block */, nullptr /* time */, &time_max)) {
+                throw std::logic_error("ScanForWalletTransactions returned invalid block hash");
+            }
+            return time_max + TIMESTAMP_WINDOW + 1;
         }
     }
     return startTime;
 }
 
 /**
- * Scan the block chain (starting in pindexStart) for transactions
+ * Scan the block chain (starting in start_block) for transactions
  * from or to us. If fUpdate is true, found transactions that already
  * exist in the wallet will be updated.
  *
- * @param[in] pindexStop if not a nullptr, the scan will stop at this block-index
- * @param[out] failed_block if FAILURE is returned, the most recent block
- *     that could not be scanned, otherwise nullptr
- * @param[out] stop_block the most recent block that could be scanned,
- *     otherwise nullptr if no block could be scanned
+ * @param[in] start_block if not null, the scan will start at this block instead
+ *            of the genesis block
+ * @param[in] stop_block if not null, the scan will stop at this block instead
+ *            of the chain tip
  *
  * @return ScanResult indicating success or failure of the scan. SUCCESS if
  * scan was successful. FAILURE if a complete rescan was not possible (due to
  * pruning or corruption). USER_ABORT if the rescan was aborted before it
  * could complete.
  *
- * @pre Caller needs to make sure pindexStop (and the optional pindexStart) are on
+ * @pre Caller needs to make sure start_block (and the optional stop_block) are on
  * the main chain after to the addition of any new keys you want to detect
  * transactions for.
  */
-CWallet::ScanResult CWallet::ScanForWalletTransactions(const CBlockIndex* const pindexStart, const CBlockIndex* const pindexStop, const WalletRescanReserver& reserver, const CBlockIndex*& failed_block, const CBlockIndex*& stop_block, bool fUpdate)
+CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_block, const uint256& stop_block, const WalletRescanReserver& reserver, bool fUpdate)
 {
     int64_t nNow = GetTime();
-    const CChainParams& chainParams = Params();
 
     assert(reserver.isReserved());
-    if (pindexStop) {
-        assert(pindexStop->nHeight >= pindexStart->nHeight);
-    }
 
-    const CBlockIndex* pindex = pindexStart;
-    failed_block = nullptr;
-    stop_block = nullptr;
+    uint256 block_hash = start_block;
+    ScanResult result;
 
-    if (pindex) WalletLogPrintf("Rescan started from block %d...\n", pindex->nHeight);
+    WalletLogPrintf("Rescan started from block %s...\n", start_block.ToString());
 
     {
         fAbortRescan = false;
         ShowProgress(strprintf("%s " + _("Rescanning..."), GetDisplayName()), 0); // show rescan progress in GUI as dialog or on splashscreen, if -rescan on startup
-        CBlockIndex* tip = nullptr;
+        uint256 tip_hash;
+        Optional<int> block_height;
         double progress_begin;
         double progress_end;
         {
             auto locked_chain = chain().lock();
-            progress_begin = GuessVerificationProgress(chainParams.TxData(), pindex);
-            if (pindexStop == nullptr) {
-                tip = chainActive.Tip();
-                progress_end = GuessVerificationProgress(chainParams.TxData(), tip);
-            } else {
-                progress_end = GuessVerificationProgress(chainParams.TxData(), pindexStop);
+            if (Optional<int> tip_height = locked_chain->getHeight()) {
+                tip_hash = locked_chain->getBlockHash(*tip_height);
             }
+            block_height = locked_chain->getBlockHeight(block_hash);
+            progress_begin = chain().guessVerificationProgress(block_hash);
+            progress_end = chain().guessVerificationProgress(stop_block.IsNull() ? tip_hash : stop_block);
         }
         double progress_current = progress_begin;
-        while (pindex && !fAbortRescan && !ShutdownRequested()) {
-            if (pindex->nHeight % 100 == 0 && progress_end - progress_begin > 0.0) {
+        while (block_height && !fAbortRescan && !ShutdownRequested()) {
+            if (*block_height % 100 == 0 && progress_end - progress_begin > 0.0) {
                 ShowProgress(strprintf("%s " + _("Rescanning..."), GetDisplayName()), std::max(1, std::min(99, (int)((progress_current - progress_begin) / (progress_end - progress_begin) * 100))));
             }
             if (GetTime() >= nNow + 60) {
                 nNow = GetTime();
-                WalletLogPrintf("Still rescanning. At block %d. Progress=%f\n", pindex->nHeight, progress_current);
+                WalletLogPrintf("Still rescanning. At block %d. Progress=%f\n", *block_height, progress_current);
             }
 
             CBlock block;
-            if (ReadBlockFromDisk(block, pindex, Params().GetConsensus())) {
+            if (chain().findBlock(block_hash, &block) && !block.IsNull()) {
                 auto locked_chain = chain().lock();
                 LOCK(cs_wallet);
-                if (pindex && !chainActive.Contains(pindex)) {
+                if (!locked_chain->getBlockHeight(block_hash)) {
                     // Abort scan if current block is no longer active, to prevent
                     // marking transactions as coming from the wrong block.
-                    failed_block = pindex;
+                    // TODO: This should return success instead of failure, see
+                    // https://github.com/bitcoin/bitcoin/pull/14711#issuecomment-458342518
+                    result.failed_block = block_hash;
+                    result.status = ScanResult::FAILURE;
                     break;
                 }
                 for (size_t posInBlock = 0; posInBlock < block.vtx.size(); ++posInBlock) {
-                    SyncTransaction(block.vtx[posInBlock], pindex, posInBlock, fUpdate);
+                    SyncTransaction(block.vtx[posInBlock], block_hash, posInBlock, fUpdate);
                 }
                 // scan succeeded, record block as most recent successfully scanned
-                stop_block = pindex;
+                result.stop_block = block_hash;
+                result.stop_height = *block_height;
             } else {
                 // could not scan block, keep scanning but record this block as the most recent failure
-                failed_block = pindex;
+                result.failed_block = block_hash;
+                result.status = ScanResult::FAILURE;
             }
-            if (pindex == pindexStop) {
+            if (block_hash == stop_block) {
                 break;
             }
             {
                 auto locked_chain = chain().lock();
-                pindex = chainActive.Next(pindex);
-                progress_current = GuessVerificationProgress(chainParams.TxData(), pindex);
-                if (pindexStop == nullptr && tip != chainActive.Tip()) {
-                    tip = chainActive.Tip();
+                Optional<int> tip_height = locked_chain->getHeight();
+                if (!tip_height || *tip_height <= block_height || !locked_chain->getBlockHeight(block_hash)) {
+                    // break successfully when rescan has reached the tip, or
+                    // previous block is no longer on the chain due to a reorg
+                    break;
+                }
+
+                // increment block and verification progress
+                block_hash = locked_chain->getBlockHash(++*block_height);
+                progress_current = chain().guessVerificationProgress(block_hash);
+
+                // handle updated tip hash
+                const uint256 prev_tip_hash = tip_hash;
+                tip_hash = locked_chain->getBlockHash(*tip_height);
+                if (stop_block.IsNull() && prev_tip_hash != tip_hash) {
                     // in case the tip has changed, update progress max
-                    progress_end = GuessVerificationProgress(chainParams.TxData(), tip);
+                    progress_end = chain().guessVerificationProgress(tip_hash);
                 }
             }
         }
         ShowProgress(strprintf("%s " + _("Rescanning..."), GetDisplayName()), 100); // hide progress dialog in GUI
-        if (pindex && fAbortRescan) {
-            WalletLogPrintf("Rescan aborted at block %d. Progress=%f\n", pindex->nHeight, progress_current);
-            return ScanResult::USER_ABORT;
-        } else if (pindex && ShutdownRequested()) {
-            WalletLogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", pindex->nHeight, progress_current);
-            return ScanResult::USER_ABORT;
+        if (block_height && fAbortRescan) {
+            WalletLogPrintf("Rescan aborted at block %d. Progress=%f\n", block_height.value_or(0), progress_current);
+            result.status = ScanResult::USER_ABORT;
+        } else if (block_height && ShutdownRequested()) {
+            WalletLogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", block_height.value_or(0), progress_current);
+            result.status = ScanResult::USER_ABORT;
         }
     }
-    if (failed_block) {
-        return ScanResult::FAILURE;
-    } else {
-        return ScanResult::SUCCESS;
-    }
+    return result;
 }
 
 void CWallet::ReacceptWalletTransactions()
@@ -4194,8 +4205,7 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(interfaces::Chain& chain,
         nStart = GetTimeMillis();
         {
             WalletRescanReserver reserver(walletInstance.get());
-            const CBlockIndex *stop_block, *failed_block;
-            if (!reserver.reserve() || (ScanResult::SUCCESS != walletInstance->ScanForWalletTransactions(pindexRescan, nullptr, reserver, failed_block, stop_block, true))) {
+            if (!reserver.reserve() || (ScanResult::SUCCESS != walletInstance->ScanForWalletTransactions(pindexRescan->GetBlockHash(), {} /* stop block */, reserver, true /* update */).status)) {
                 InitError(_("Failed to rescan the wallet during initialization"));
                 return nullptr;
             }
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index d8981f7385..7a541db778 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -678,8 +678,8 @@ private:
     void SyncMetaData(std::pair<TxSpends::iterator, TxSpends::iterator>) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /* Used by TransactionAddedToMemorypool/BlockConnected/Disconnected/ScanForWalletTransactions.
-     * Should be called with pindexBlock and posInBlock if this is for a transaction that is included in a block. */
-    void SyncTransaction(const CTransactionRef& tx, const CBlockIndex *pindex = nullptr, int posInBlock = 0, bool update_tx = true) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+     * Should be called with non-zero block_hash and posInBlock if this is for a transaction that is included in a block. */
+    void SyncTransaction(const CTransactionRef& tx, const uint256& block_hash, int posInBlock = 0, bool update_tx = true) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 
     /* the HD chain data model (external chain counters) */
     CHDChain hdChain;
@@ -909,12 +909,22 @@ public:
     void BlockDisconnected(const std::shared_ptr<const CBlock>& pblock) override;
     int64_t RescanFromTime(int64_t startTime, const WalletRescanReserver& reserver, bool update);
 
-    enum class ScanResult {
-        SUCCESS,
-        FAILURE,
-        USER_ABORT
+    struct ScanResult {
+        enum { SUCCESS, FAILURE, USER_ABORT } status = SUCCESS;
+
+        //! Hash and height of most recent block that was successfully scanned.
+        //! Unset if no blocks were scanned due to read errors or the chain
+        //! being empty.
+        uint256 stop_block;
+        Optional<int> stop_height;
+
+        //! Height of the most recent block that could not be scanned due to
+        //! read errors or pruning. Will be set if status is FAILURE, unset if
+        //! status is SUCCESS, and may or may not be set if status is
+        //! USER_ABORT.
+        uint256 failed_block;
     };
-    ScanResult ScanForWalletTransactions(const CBlockIndex* const pindexStart, const CBlockIndex* const pindexStop, const WalletRescanReserver& reserver, const CBlockIndex*& failed_block, const CBlockIndex*& stop_block, bool fUpdate = false);
+    ScanResult ScanForWalletTransactions(const uint256& first_block, const uint256& last_block, const WalletRescanReserver& reserver, bool fUpdate);
     void TransactionRemovedFromMempool(const CTransactionRef &ptx) override;
     void ReacceptWalletTransactions();
     void ResendWalletTransactions(int64_t nBestBlockTime, CConnman* connman) override EXCLUSIVE_LOCKS_REQUIRED(cs_main);