Merge bitcoin/bitcoin#24865: rpc: Enable wallet import on pruned nodes and add test

564b580bf07742483a140c7c095b896a6d5d6cad test: Introduce MIN_BLOCKS_TO_KEEP constant (Aurèle Oulès)
71d9a7c03b44236c2fea2b74f92a69234d29f717 test: Wallet imports on pruned nodes (Aurèle Oulès)
e6906fcf9e4d5692ead6c9bf5a2e11673315a1f5 rpc: Enable wallet import on pruned nodes (Aurèle Oulès)

Pull request description:

  Reopens #16037

  I have rebased the PR, addressed the comments of the original PR and added a functional test.

  > Before this change importwallet fails if any block is pruned. This PR makes it possible to importwallet if all required blocks aren't pruned. This is possible because the dump format includes key timestamps.

  For reviewers:
  `python test/functional/wallet_pruning.py --nocleanup` will generate a large blockchain (~700MB) that can be used to manually test wallet imports on a pruned node. Node0 is not pruned, while node1 is.

ACKs for top commit:
  kouloumos:
    ACK 564b580bf07742483a140c7c095b896a6d5d6cad
  achow101:
    reACK 564b580bf07742483a140c7c095b896a6d5d6cad
  furszy:
    ACK 564b580
  w0xlt:
    ACK https://github.com/bitcoin/bitcoin/pull/24865/commits/564b580bf07742483a140c7c095b896a6d5d6cad

Tree-SHA512: b345a6c455fcb6581cdaa5f7a55d79e763a55cb08c81d66be5b12794985d79cd51b9b39bdcd0f7ba0a2a2643e9b2ddc49310ff03d16b430df2f74e990800eabf

1 files changed, 19 insertions, 12 deletions

diff --git a/src/wallet/rpc/backup.cpp b/src/wallet/rpc/backup.cpp
index ddf10cae15..a85302c77d 100644
--- a/src/wallet/rpc/backup.cpp
+++ b/src/wallet/rpc/backup.cpp
@@ -93,6 +93,22 @@ static void RescanWallet(CWallet& wallet, const WalletRescanReserver& reserver,
     }
 }
 
+static void EnsureBlockDataFromTime(const CWallet& wallet, int64_t timestamp)
+{
+    auto& chain{wallet.chain()};
+    if (!chain.havePruned()) {
+        return;
+    }
+
+    int height{0};
+    const bool found{chain.findFirstBlockWithTimeAndHeight(timestamp - TIMESTAMP_WINDOW, 0, FoundBlock().height(height))};
+
+    uint256 tip_hash{WITH_LOCK(wallet.cs_wallet, return wallet.GetLastBlockHash())};
+    if (found && !chain.hasBlocks(tip_hash, height)) {
+        throw JSONRPCError(RPC_WALLET_ERROR, strprintf("Pruned blocks from height %d required to import keys. Use RPC call getblockchaininfo to determine your pruned height.", height));
+    }
+}
+
 RPCHelpMan importprivkey()
 {
     return RPCHelpMan{"importprivkey",
@@ -504,13 +520,6 @@ RPCHelpMan importwallet()
 
     EnsureLegacyScriptPubKeyMan(*pwallet, true);
 
-    if (pwallet->chain().havePruned()) {
-        // Exit early and print an error.
-        // If a block is pruned after this check, we will import the key(s),
-        // but fail the rescan with a generic error.
-        throw JSONRPCError(RPC_WALLET_ERROR, "Importing wallets is disabled when blocks are pruned");
-    }
-
     WalletRescanReserver reserver(*pwallet);
     if (!reserver.reserve()) {
         throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
@@ -565,15 +574,18 @@ RPCHelpMan importwallet()
                         fLabel = true;
                     }
                 }
+                nTimeBegin = std::min(nTimeBegin, nTime);
                 keys.push_back(std::make_tuple(key, nTime, fLabel, strLabel));
             } else if(IsHex(vstr[0])) {
                 std::vector<unsigned char> vData(ParseHex(vstr[0]));
                 CScript script = CScript(vData.begin(), vData.end());
                 int64_t birth_time = ParseISO8601DateTime(vstr[1]);
+                if (birth_time > 0) nTimeBegin = std::min(nTimeBegin, birth_time);
                 scripts.push_back(std::pair<CScript, int64_t>(script, birth_time));
             }
         }
         file.close();
+        EnsureBlockDataFromTime(*pwallet, nTimeBegin);
         // We now know whether we are importing private keys, so we can error if private keys are disabled
         if (keys.size() > 0 && pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
             pwallet->chain().showProgress("", 100, false); // hide progress dialog in GUI
@@ -602,8 +614,6 @@ RPCHelpMan importwallet()
 
             if (has_label)
                 pwallet->SetAddressBook(PKHash(keyid), label, "receive");
-
-            nTimeBegin = std::min(nTimeBegin, time);
             progress++;
         }
         for (const auto& script_pair : scripts) {
@@ -616,9 +626,6 @@ RPCHelpMan importwallet()
                 fGood = false;
                 continue;
             }
-            if (time > 0) {
-                nTimeBegin = std::min(nTimeBegin, time);
-            }
 
             progress++;
         }