Do not allow duplicate GENESIS block creation - #1556 (#1612)

* Add a check for GENESIS transaction

* Add test and fixture

* Removed database query for GENESIS block

* Undo log level change

bigchaindb/common/exceptions.py

@@ -19,10 +19,6 @@ class StartupError(BigchainDBError):
     """Raised when there is an error starting up the system"""
 
 
-class GenesisBlockAlreadyExistsError(BigchainDBError):
-    """Raised when trying to create the already existing genesis block"""
-
-
 class CyclicBlockchainError(BigchainDBError):
     """Raised when there is a cycle in the blockchain"""
 
@@ -110,3 +106,7 @@ class DuplicateTransaction(ValidationError):
 
 class ThresholdTooDeep(ValidationError):
     """Raised if threshold condition is too deep"""
+
+
+class GenesisBlockAlreadyExistsError(ValidationError):
+    """Raised when trying to create the already existing genesis block"""

bigchaindb/pipelines/block.py

@@ -13,7 +13,8 @@ import bigchaindb
 from bigchaindb import backend
 from bigchaindb.backend.changefeed import ChangeFeed
 from bigchaindb.models import Transaction
-from bigchaindb.common.exceptions import ValidationError
+from bigchaindb.common.exceptions import (ValidationError,
+                                          GenesisBlockAlreadyExistsError)
 from bigchaindb import Bigchain
 
 
@@ -73,6 +74,14 @@ class BlockPipeline:
 
         # If transaction is not valid it should not be included
         try:
+            # Do not allow an externally submitted GENESIS transaction.
+            # A simple check is enough as a pipeline is started only after the
+            # creation of GENESIS block, or after the verification of a GENESIS
+            # block. Voting will fail at a later stage if the GENESIS block is
+            # absent.
+            if tx.operation == Transaction.GENESIS:
+                raise GenesisBlockAlreadyExistsError('Duplicate GENESIS transaction')
+
             tx.validate(self.bigchain)
             return tx
         except ValidationError as e:

tests/conftest.py

@@ -506,3 +506,12 @@ def wsserver_port(wsserver_config):
 @pytest.fixture
 def wsserver_base_url(wsserver_scheme, wsserver_host, wsserver_port):
     return '{}://{}:{}'.format(wsserver_scheme, wsserver_host, wsserver_port)
+
+
+@pytest.fixture
+def genesis_tx(b, user_pk):
+    from bigchaindb.models import Transaction
+    tx = Transaction.create([b.me], [([user_pk], 1)])
+    tx.operation = Transaction.GENESIS
+    genesis_tx = tx.sign([b.me_private])
+    return genesis_tx

tests/pipelines/test_block_creation.py

@@ -226,3 +226,14 @@ def test_block_snowflake(create_tx, signed_transfer_tx):
     snowflake.send(signed_transfer_tx)
     snowflake.send(create_tx)
     assert snowflake.send(None) == [create_tx, signed_transfer_tx]
+
+
+@pytest.mark.bdb
+@pytest.mark.genesis
+def test_duplicate_genesis_transaction(b, genesis_block, genesis_tx):
+    # Try to create a duplicate GENESIS transaction
+    # Expect None as it will be rejected during validation
+
+    from bigchaindb.pipelines import block
+    block_maker = block.BlockPipeline()
+    assert block_maker.validate_tx(genesis_tx.to_dict()) is None