src/wallet/salvage.cpp
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <streams.h>
#include <util/fs.h>
#include <util/translation.h>
#include <wallet/bdb.h>
#include <wallet/salvage.h>
#include <wallet/wallet.h>
#include <wallet/walletdb.h>
#include <db_cxx.h>
namespace wallet {
/* End of headers, beginning of key/value data */
static const char *HEADER_END = "HEADER=END";
/* End of key/value data */
static const char *DATA_END = "DATA=END";
typedef std::pair<std::vector<unsigned char>, std::vector<unsigned char> > KeyValPair;
class DummyCursor : public DatabaseCursor
{
Status Next(DataStream& key, DataStream& value) override { return Status::FAIL; }
};
/** RAII class that provides access to a DummyDatabase. Never fails. */
class DummyBatch : public DatabaseBatch
{
private:
bool ReadKey(DataStream&& key, DataStream& value) override { return true; }
bool WriteKey(DataStream&& key, DataStream&& value, bool overwrite=true) override { return true; }
bool EraseKey(DataStream&& key) override { return true; }
bool HasKey(DataStream&& key) override { return true; }
bool ErasePrefix(Span<const std::byte> prefix) override { return true; }
public:
void Flush() override {}
void Close() override {}
std::unique_ptr<DatabaseCursor> GetNewCursor() override { return std::make_unique<DummyCursor>(); }
std::unique_ptr<DatabaseCursor> GetNewPrefixCursor(Span<const std::byte> prefix) override { return GetNewCursor(); }
bool TxnBegin() override { return true; }
bool TxnCommit() override { return true; }
bool TxnAbort() override { return true; }
};
/** A dummy WalletDatabase that does nothing and never fails. Only used by salvage.
**/
class DummyDatabase : public WalletDatabase
{
public:
void Open() override {};
void AddRef() override {}
void RemoveRef() override {}
bool Rewrite(const char* pszSkip=nullptr) override { return true; }
bool Backup(const std::string& strDest) const override { return true; }
void Close() override {}
void Flush() override {}
bool PeriodicFlush() override { return true; }
void IncrementUpdateCounter() override { ++nUpdateCounter; }
void ReloadDbEnv() override {}
std::string Filename() override { return "dummy"; }
std::string Format() override { return "dummy"; }
std::unique_ptr<DatabaseBatch> MakeBatch(bool flush_on_close = true) override { return std::make_unique<DummyBatch>(); }
};
bool RecoverDatabaseFile(const ArgsManager& args, const fs::path& file_path, bilingual_str& error, std::vector<bilingual_str>& warnings)
{
DatabaseOptions options;
DatabaseStatus status;
ReadDatabaseArgs(args, options);
options.require_existing = true;
options.verify = false;
options.require_format = DatabaseFormat::BERKELEY;
std::unique_ptr<WalletDatabase> database = MakeDatabase(file_path, options, status, error);
if (!database) return false;
BerkeleyDatabase& berkeley_database = static_cast<BerkeleyDatabase&>(*database);
std::string filename = berkeley_database.Filename();
std::shared_ptr<BerkeleyEnvironment> env = berkeley_database.env;
if (!env->Open(error)) {
return false;
}
// Recovery procedure:
// move wallet file to walletfilename.timestamp.bak
// Call Salvage with fAggressive=true to
// get as much data as possible.
// Rewrite salvaged data to fresh wallet file
// Rescan so any missing transactions will be
// found.
int64_t now = GetTime();
std::string newFilename = strprintf("%s.%d.bak", filename, now);
int result = env->dbenv->dbrename(nullptr, filename.c_str(), nullptr,
newFilename.c_str(), DB_AUTO_COMMIT);
if (result != 0)
{
error = strprintf(Untranslated("Failed to rename %s to %s"), filename, newFilename);
return false;
}
/**
* Salvage data from a file. The DB_AGGRESSIVE flag is being used (see berkeley DB->verify() method documentation).
* key/value pairs are appended to salvagedData which are then written out to a new wallet file.
* NOTE: reads the entire database into memory, so cannot be used
* for huge databases.
*/
std::vector<KeyValPair> salvagedData;
std::stringstream strDump;
Db db(env->dbenv.get(), 0);
result = db.verify(newFilename.c_str(), nullptr, &strDump, DB_SALVAGE | DB_AGGRESSIVE);
if (result == DB_VERIFY_BAD) {
warnings.push_back(Untranslated("Salvage: Database salvage found errors, all data may not be recoverable."));
}
if (result != 0 && result != DB_VERIFY_BAD) {
error = strprintf(Untranslated("Salvage: Database salvage failed with result %d."), result);
return false;
}
// Format of bdb dump is ascii lines:
// header lines...
// HEADER=END
// hexadecimal key
// hexadecimal value
// ... repeated
// DATA=END
std::string strLine;
while (!strDump.eof() && strLine != HEADER_END)
getline(strDump, strLine); // Skip past header
std::string keyHex, valueHex;
while (!strDump.eof() && keyHex != DATA_END) {
getline(strDump, keyHex);
if (keyHex != DATA_END) {
if (strDump.eof())
break;
getline(strDump, valueHex);
if (valueHex == DATA_END) {
warnings.push_back(Untranslated("Salvage: WARNING: Number of keys in data does not match number of values."));
break;
}
salvagedData.emplace_back(ParseHex(keyHex), ParseHex(valueHex));
}
}
bool fSuccess;
if (keyHex != DATA_END) {
warnings.push_back(Untranslated("Salvage: WARNING: Unexpected end of file while reading salvage output."));
fSuccess = false;
} else {
fSuccess = (result == 0);
}
if (salvagedData.empty())
{
error = strprintf(Untranslated("Salvage(aggressive) found no records in %s."), newFilename);
return false;
}
std::unique_ptr<Db> pdbCopy = std::make_unique<Db>(env->dbenv.get(), 0);
int ret = pdbCopy->open(nullptr, // Txn pointer
filename.c_str(), // Filename
"main", // Logical db name
DB_BTREE, // Database type
DB_CREATE, // Flags
0);
if (ret > 0) {
error = strprintf(Untranslated("Cannot create database file %s"), filename);
pdbCopy->close(0);
return false;
}
DbTxn* ptxn = env->TxnBegin(DB_TXN_WRITE_NOSYNC);
CWallet dummyWallet(nullptr, "", std::make_unique<DummyDatabase>());
for (KeyValPair& row : salvagedData)
{
/* Filter for only private key type KV pairs to be added to the salvaged wallet */
DataStream ssKey{row.first};
DataStream ssValue(row.second);
std::string strType, strErr;
// We only care about KEY, MASTER_KEY, CRYPTED_KEY, and HDCHAIN types
ssKey >> strType;
bool fReadOK = false;
if (strType == DBKeys::KEY) {
fReadOK = LoadKey(&dummyWallet, ssKey, ssValue, strErr);
} else if (strType == DBKeys::CRYPTED_KEY) {
fReadOK = LoadCryptedKey(&dummyWallet, ssKey, ssValue, strErr);
} else if (strType == DBKeys::MASTER_KEY) {
fReadOK = LoadEncryptionKey(&dummyWallet, ssKey, ssValue, strErr);
} else if (strType == DBKeys::HDCHAIN) {
fReadOK = LoadHDChain(&dummyWallet, ssValue, strErr);
} else {
continue;
}
if (!fReadOK)
{
warnings.push_back(strprintf(Untranslated("WARNING: WalletBatch::Recover skipping %s: %s"), strType, strErr));
continue;
}
Dbt datKey(row.first.data(), row.first.size());
Dbt datValue(row.second.data(), row.second.size());
int ret2 = pdbCopy->put(ptxn, &datKey, &datValue, DB_NOOVERWRITE);
if (ret2 > 0)
fSuccess = false;
}
ptxn->commit(0);
pdbCopy->close(0);
return fSuccess;
}
} // namespace wallet