From 4d2d6045a4784d576d56299244b9f76a5909904b Mon Sep 17 00:00:00 2001
From: Russell Yanofsky <russ@yanofsky.org>
Date: Mon, 15 May 2017 09:11:03 -0400
Subject: Fix importmulti failure to return rescan errors

An off-by-one-block bug in importmulti rescan logic could cause it to return
success in an edge case even when a rescan was not successful. The case where
this would happen is if there were multiple blocks in a row with the same
GetBlockTimeMax() value, and the last block was scanned successfully, but one
or more of the earlier blocks was not readable.
---
 src/wallet/test/wallet_tests.cpp | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

(limited to 'src/wallet/test/wallet_tests.cpp')

diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 8eeba72a06..bdfebd6b73 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -364,6 +364,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     LOCK(cs_main);
 
     // Cap last block file size, and mine new block in a new block file.
+    CBlockIndex* const nullBlock = nullptr;
     CBlockIndex* oldTip = chainActive.Tip();
     GetBlockFileInfo(oldTip->GetBlockPos().nFile)->nSize = MAX_BLOCKFILE_SIZE;
     CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
@@ -375,7 +376,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
         CWallet wallet;
         LOCK(wallet.cs_wallet);
         wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
-        BOOST_CHECK_EQUAL(oldTip, wallet.ScanForWalletTransactions(oldTip));
+        BOOST_CHECK_EQUAL(nullBlock, wallet.ScanForWalletTransactions(oldTip));
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 100 * COIN);
     }
 
@@ -389,7 +390,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
         CWallet wallet;
         LOCK(wallet.cs_wallet);
         wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
-        BOOST_CHECK_EQUAL(newTip, wallet.ScanForWalletTransactions(oldTip));
+        BOOST_CHECK_EQUAL(oldTip, wallet.ScanForWalletTransactions(oldTip));
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 50 * COIN);
     }
 
@@ -413,7 +414,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
         CKey futureKey;
         futureKey.MakeNewKey(true);
         key.pushKV("scriptPubKey", HexStr(GetScriptForRawPubKey(futureKey.GetPubKey())));
-        key.pushKV("timestamp", newTip->GetBlockTimeMax() + TIMESTAMP_WINDOW);
+        key.pushKV("timestamp", newTip->GetBlockTimeMax() + TIMESTAMP_WINDOW + 1);
         key.pushKV("internal", UniValue(true));
         keys.push_back(key);
         JSONRPCRequest request;
@@ -421,20 +422,17 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
         request.params.push_back(keys);
 
         UniValue response = importmulti(request);
-        BOOST_CHECK_EQUAL(response.write(), strprintf("[{\"success\":false,\"error\":{\"code\":-1,\"message\":\"Failed to rescan before time %d, transactions may be missing.\"}},{\"success\":true}]", newTip->GetBlockTimeMax()));
+        BOOST_CHECK_EQUAL(response.write(),
+            strprintf("[{\"success\":false,\"error\":{\"code\":-1,\"message\":\"Rescan failed for key with creation "
+                      "timestamp %d. There was an error reading a block from time %d, which is after or within %d "
+                      "seconds of key creation, and could contain transactions pertaining to the key. As a result, "
+                      "transactions and coins using this key may not appear in the wallet. This error could be caused "
+                      "by pruning or data corruption (see bitcoind log for details) and could be dealt with by "
+                      "downloading and rescanning the relevant blocks (see -reindex and -rescan "
+                      "options).\"}},{\"success\":true}]",
+                              0, oldTip->GetBlockTimeMax(), TIMESTAMP_WINDOW));
         ::pwalletMain = backup;
     }
-
-    // Verify ScanForWalletTransactions does not return null when the scan is
-    // elided due to the nTimeFirstKey optimization.
-    {
-        CWallet wallet;
-        {
-            LOCK(wallet.cs_wallet);
-            wallet.UpdateTimeFirstKey(newTip->GetBlockTime() + 7200 + 1);
-        }
-        BOOST_CHECK_EQUAL(newTip, wallet.ScanForWalletTransactions(newTip));
-    }
 }
 
 // Check that GetImmatureCredit() returns a newly calculated value instead of
-- 
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