dbwrapper: Pass parent CDBWrapper into CDBBatch and CDBIterator

Pass parent wrapper directly instead of obfuscation key. This
makes it possible for other databases which re-use this code
to use other properties from the database.

Add a namespace dbwrapper_private for private functions to be used
only in dbwrapper.h/cpp and dbwrapper_tests.

Author: laanwj

src/dbwrapper.cpp

@@ -136,12 +136,16 @@ bool CDBWrapper::IsEmpty()
     return !(it->Valid());
 }
 
-const std::vector<unsigned char>& CDBWrapper::GetObfuscateKey() const
-{
-    return obfuscate_key;
-}
-
 CDBIterator::~CDBIterator() { delete piter; }
 bool CDBIterator::Valid() { return piter->Valid(); }
 void CDBIterator::SeekToFirst() { piter->SeekToFirst(); }
 void CDBIterator::Next() { piter->Next(); }
+
+namespace dbwrapper_private {
+
+const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper &w)
+{
+    return w.obfuscate_key;
+}
+
+};

src/dbwrapper.h

@@ -25,20 +25,34 @@ class dbwrapper_error : public std::runtime_error
 
 void HandleError(const leveldb::Status& status);
 
+class CDBWrapper;
+
+/** These should be considered an implementation detail of the specific database.
+ */
+namespace dbwrapper_private {
+
+/** Work around circular dependency, as well as for testing in dbwrapper_tests.
+ * Database obfuscation should be considered an implementation detail of the
+ * specific database.
+ */
+const std::vector<unsigned char>& GetObfuscateKey(const CDBWrapper &w);
+
+};
+
 /** Batch of changes queued to be written to a CDBWrapper */
 class CDBBatch
 {
     friend class CDBWrapper;
 
 private:
+    const CDBWrapper &parent;
     leveldb::WriteBatch batch;
-    const std::vector<unsigned char> *obfuscate_key;
 
 public:
     /**
-     * @param[in] obfuscate_key    If passed, XOR data with this key.
+     * @param[in] parent    CDBWrapper that this batch is to be submitted to
      */
-    CDBBatch(const std::vector<unsigned char> *obfuscate_key) : obfuscate_key(obfuscate_key) { };
+    CDBBatch(const CDBWrapper &parent) : parent(parent) { };
 
     template <typename K, typename V>
     void Write(const K& key, const V& value)
@@ -51,7 +65,7 @@ class CDBBatch
         CDataStream ssValue(SER_DISK, CLIENT_VERSION);
         ssValue.reserve(ssValue.GetSerializeSize(value));
         ssValue << value;
-        ssValue.Xor(*obfuscate_key);
+        ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
         leveldb::Slice slValue(&ssValue[0], ssValue.size());
 
         batch.Put(slKey, slValue);
@@ -72,17 +86,17 @@ class CDBBatch
 class CDBIterator
 {
 private:
+    const CDBWrapper &parent;
     leveldb::Iterator *piter;
-    const std::vector<unsigned char> *obfuscate_key;
 
 public:
 
     /**
+     * @param[in] parent           Parent CDBWrapper instance.
      * @param[in] piterIn          The original leveldb iterator.
-     * @param[in] obfuscate_key    If passed, XOR data with this key.
      */
-    CDBIterator(leveldb::Iterator *piterIn, const std::vector<unsigned char>* obfuscate_key) :
-        piter(piterIn), obfuscate_key(obfuscate_key) { };
+    CDBIterator(const CDBWrapper &parent, leveldb::Iterator *piterIn) :
+        parent(parent), piter(piterIn) { };
     ~CDBIterator();
 
     bool Valid();
@@ -118,7 +132,7 @@ class CDBIterator
         leveldb::Slice slValue = piter->value();
         try {
             CDataStream ssValue(slValue.data(), slValue.data() + slValue.size(), SER_DISK, CLIENT_VERSION);
-            ssValue.Xor(*obfuscate_key);
+            ssValue.Xor(dbwrapper_private::GetObfuscateKey(parent));
             ssValue >> value;
         } catch (const std::exception&) {
             return false;
@@ -134,6 +148,7 @@ class CDBIterator
 
 class CDBWrapper
 {
+    friend const std::vector<unsigned char>& dbwrapper_private::GetObfuscateKey(const CDBWrapper &w);
 private:
     //! custom environment this database is using (may be NULL in case of default environment)
     leveldb::Env* penv;
@@ -208,7 +223,7 @@ class CDBWrapper
     template <typename K, typename V>
     bool Write(const K& key, const V& value, bool fSync = false)
     {
-        CDBBatch batch(&obfuscate_key);
+        CDBBatch batch(*this);
         batch.Write(key, value);
         return WriteBatch(batch, fSync);
     }
@@ -235,7 +250,7 @@ class CDBWrapper
     template <typename K>
     bool Erase(const K& key, bool fSync = false)
     {
-        CDBBatch batch(&obfuscate_key);
+        CDBBatch batch(*this);
         batch.Erase(key);
         return WriteBatch(batch, fSync);
     }
@@ -250,24 +265,19 @@ class CDBWrapper
 
     bool Sync()
     {
-        CDBBatch batch(&obfuscate_key);
+        CDBBatch batch(*this);
         return WriteBatch(batch, true);
     }
 
     CDBIterator *NewIterator()
     {
-        return new CDBIterator(pdb->NewIterator(iteroptions), &obfuscate_key);
+        return new CDBIterator(*this, pdb->NewIterator(iteroptions));
     }
 
     /**
      * Return true if the database managed by this class contains no entries.
      */
     bool IsEmpty();
-
-    /**
-     * Accessor for obfuscate_key.
-     */
-    const std::vector<unsigned char>& GetObfuscateKey() const;
 };
 
 #endif // BITCOIN_DBWRAPPER_H

src/test/dbwrapper_tests.cpp

@@ -39,7 +39,7 @@ BOOST_AUTO_TEST_CASE(dbwrapper)
         uint256 res;
 
         // Ensure that we're doing real obfuscation when obfuscate=true
-        BOOST_CHECK(obfuscate != is_null_key(dbw.GetObfuscateKey()));
+        BOOST_CHECK(obfuscate != is_null_key(dbwrapper_private::GetObfuscateKey(dbw)));
 
         BOOST_CHECK(dbw.Write(key, in));
         BOOST_CHECK(dbw.Read(key, res));
@@ -64,7 +64,7 @@ BOOST_AUTO_TEST_CASE(dbwrapper_batch)
         uint256 in3 = GetRandHash();
 
         uint256 res;
-        CDBBatch batch(&dbw.GetObfuscateKey());
+        CDBBatch batch(dbw);
 
         batch.Write(key, in);
         batch.Write(key2, in2);
@@ -156,7 +156,7 @@ BOOST_AUTO_TEST_CASE(existing_data_no_obfuscate)
     BOOST_CHECK_EQUAL(res2.ToString(), in.ToString());
 
     BOOST_CHECK(!odbw.IsEmpty()); // There should be existing data
-    BOOST_CHECK(is_null_key(odbw.GetObfuscateKey())); // The key should be an empty string
+    BOOST_CHECK(is_null_key(dbwrapper_private::GetObfuscateKey(odbw))); // The key should be an empty string
 
     uint256 in2 = GetRandHash();
     uint256 res3;
@@ -193,7 +193,7 @@ BOOST_AUTO_TEST_CASE(existing_data_reindex)
     // Check that the key/val we wrote with unobfuscated wrapper doesn't exist
     uint256 res2;
     BOOST_CHECK(!odbw.Read(key, res2));
-    BOOST_CHECK(!is_null_key(odbw.GetObfuscateKey()));
+    BOOST_CHECK(!is_null_key(dbwrapper_private::GetObfuscateKey(odbw)));
 
     uint256 in2 = GetRandHash();
     uint256 res3;

src/txdb.cpp

@@ -49,7 +49,7 @@ uint256 CCoinsViewDB::GetBestBlock() const {
 }
 
 bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) {
-    CDBBatch batch(&db.GetObfuscateKey());
+    CDBBatch batch(db);
     size_t count = 0;
     size_t changed = 0;
     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
@@ -139,7 +139,7 @@ void CCoinsViewDBCursor::Next()
 }
 
 bool CBlockTreeDB::WriteBatchSync(const std::vector<std::pair<int, const CBlockFileInfo*> >& fileInfo, int nLastFile, const std::vector<const CBlockIndex*>& blockinfo) {
-    CDBBatch batch(&GetObfuscateKey());
+    CDBBatch batch(*this);
     for (std::vector<std::pair<int, const CBlockFileInfo*> >::const_iterator it=fileInfo.begin(); it != fileInfo.end(); it++) {
         batch.Write(make_pair(DB_BLOCK_FILES, it->first), *it->second);
     }
@@ -155,7 +155,7 @@ bool CBlockTreeDB::ReadTxIndex(const uint256 &txid, CDiskTxPos &pos) {
 }
 
 bool CBlockTreeDB::WriteTxIndex(const std::vector<std::pair<uint256, CDiskTxPos> >&vect) {
-    CDBBatch batch(&GetObfuscateKey());
+    CDBBatch batch(*this);
     for (std::vector<std::pair<uint256,CDiskTxPos> >::const_iterator it=vect.begin(); it!=vect.end(); it++)
         batch.Write(make_pair(DB_TXINDEX, it->first), it->second);
     return WriteBatch(batch);