Merge a44a5703d11bc04db4fb8d4021b4819692014003 into 955fd86a7f4323f61ae7c30ada53dccdbed575aa

bigchaindb/client.py

@@ -90,6 +90,24 @@ class Client:
             tx, private_key=self.private_key)
         return self._push(signed_tx)
 
+    def validate(self, tx):
+        """Validate a transaction object.
+
+        If tx is a `CREATE` transaction, this method will return (True, '') even
+        without the federation signature as long as the transaction is otherwise
+        valid.
+
+        Args:
+            tx (dict): the transaction object to be validated
+
+        Return:
+            (bool, str): (True, '') if the tx is valid, else (False, errormsg)
+        """
+
+        res = requests.post(self.api_endpoint + '/transactions/validate/',
+                            json=tx)
+        return (res.json()['valid'], res.json()['error'])
+
     def _push(self, tx):
         """Submit a transaction to the Federation.
 

bigchaindb/util.py

@@ -199,7 +199,9 @@ def verify_signature(signed_transaction):
     if 'assignee' in data:
         data.pop('assignee')
 
-    signature = data.pop('signature')
+    signature = data.pop('signature', None)
+    if not signature: return False
+
     public_key_base58 = signed_transaction['transaction']['current_owner']
     public_key = PublicKey(public_key_base58)
     return public_key.verify(serialize(data), signature)

bigchaindb/web/views.py

@@ -7,7 +7,7 @@ For more information please refer to the documentation in Apiary:
 import flask
 from flask import current_app, request, Blueprint
 
-from bigchaindb import util
+from bigchaindb import util, exceptions
 
 
 basic_views = Blueprint('basic_views', __name__)
@@ -37,6 +37,7 @@ def get_transaction(tx_id):
     bigchain = current_app.config['bigchain']
 
     tx = bigchain.get_transaction(tx_id)
+    if not tx: flask.abort(404)
     return flask.jsonify(**tx)
 
 
@@ -47,12 +48,13 @@ def create_transaction():
     Return:
         A JSON string containing the data about the transaction.
     """
+
     bigchain = current_app.config['bigchain']
 
     val = {}
 
-    # `force` will try to format the body of the POST request even if the `content-type` header is not
-    # set to `application/json`
+    # `force` will try to format the body of the POST request even if the
+    # `content-type` header is not set to `application/json`
     tx = request.get_json(force=True)
 
     if tx['transaction']['operation'] == 'CREATE':
@@ -67,3 +69,38 @@ def create_transaction():
 
     return flask.jsonify(**tx)
 
+@basic_views.route('/transactions/validate/', methods=['POST'])
+def validate_transaction():
+    """API endpoint to validate transactions without pushing them to the
+    Federation. No federation node signature is required for `CREATE`
+    transactions.
+
+    Return:
+        A JSON object with the `valid` field populated with a boolean value
+        and the `error` field populated with an error message or an empty str
+    """
+
+    bigchain = current_app.config['bigchain']
+
+    tx = request.get_json(force=True)
+
+    # Always validate TRANSFER signatures; but only validate CREATE signatures
+    # if present.
+    validate_sig = True
+
+    # If a CREATE doesn't have the signature populated, then we treat it as
+    # an input to the `create` function and transform it.
+    if tx['transaction']['operation'] == 'CREATE' and 'signature' not in tx:
+        validate_sig = False
+        tx = util.transform_create(tx)
+
+    try:
+        bigchain.validate_transaction(tx)
+    except exceptions.InvalidSignature as e:
+        # We skipped signing CREATEs with the node's private key, so expect this
+        if validate_sig:
+            return flask.jsonify(valid=False, error=repr(e))
+    except Exception as e:
+        return flask.jsonify(valid=False, error=repr(e))
+
+    return flask.jsonify(valid=True, error='')

tests/test_client.py

@@ -57,3 +57,11 @@ def test_client_can_transfer_assets(mock_requests_post, client):
 
     assert util.verify_signature(tx)
 
+
+def test_client_can_validate_transaction(mock_requests_post, client):
+    from bigchaindb import util
+
+    assert client.validate({'valid': True,
+                            'error': ''}) == (True, '')
+    assert client.validate({'valid': False,
+                            'error': 'Some Error'}) == (False, 'Some Error')

tests/web/test_basic_views.py

@@ -6,8 +6,38 @@ from bigchaindb import util
 
 
 TX_ENDPOINT = '/api/v1/transactions/'
+VALIDATE_ENDPOINT = '/api/v1/transactions/validate/'
 
 
+@pytest.fixture
+def valid_create_transaction(user_public_key):
+    return util.create_tx(
+        current_owner=None,
+        new_owner=user_public_key,
+        tx_input=None,
+        operation='CREATE',
+        payload={
+            'IPFS_key': 'QmfQ5QAjvg4GtA3wg3adpnDJug8ktA1BxurVqBD8rtgVjP',
+            'creator': 'Johnathan Plunkett',
+            'title': 'The Winds of Plast'})
+
+
+@pytest.fixture
+def valid_transfer_transaction(user_public_key, user_private_key):
+    # Requires an tx_input param to create a *valid* transfer tx
+    def make_tx(tx_input):
+        return util.create_and_sign_tx(
+            private_key=user_private_key,
+            current_owner=user_public_key,
+            new_owner=user_public_key,
+            tx_input=tx_input, #Fill_me_in
+            operation='TRANSFER',
+            payload={
+                'IPFS_key': 'QmfQ5QAjvg4GtA3wg3adpnDJug8ktA1BxurVqBD8rtgVjP',
+                'creator': 'Johnathan Plunkett',
+                'title': 'The Winds of Plast 2: The Plastening'})
+    return make_tx
+
 @pytest.mark.usefixtures('inputs')
 def test_get_transaction_endpoint(b, client, user_public_key):
     input_tx = b.get_owned_ids(user_public_key).pop()
@@ -40,3 +70,34 @@ def test_post_transfer_transaction_endpoint(b, client):
     assert res.json['transaction']['current_owner'] == from_keypair[1]
     assert res.json['transaction']['new_owner'] == to_keypair[1]
 
+
+@pytest.mark.usefixtures('inputs')
+def test_post_validate_transaction_endpoint(b, client, user_public_key,
+                                            valid_create_transaction,
+                                            valid_transfer_transaction):
+    # Validate valid CREATE tx
+    res = client.post(VALIDATE_ENDPOINT,
+                      data=json.dumps(valid_create_transaction))
+    assert res.json['valid'] == True
+    assert res.json['error'] == ''
+
+    # Validate invalid CREATE tx
+    valid_create_transaction.update({'signature': 'junk'})
+    res = client.post(VALIDATE_ENDPOINT,
+                      data=json.dumps(valid_create_transaction))
+    assert res.json['valid'] == False
+    assert res.json['error'] == \
+        "OperationError('Only federation nodes can use the operation `CREATE`',)"
+
+    # Validate valid TRANSFER tx
+    res = client.post(VALIDATE_ENDPOINT, data=json.dumps(
+        valid_transfer_transaction(b.get_owned_ids(user_public_key).pop())))
+    assert res.json['valid'] == True
+    assert res.json['error'] == ''
+
+    # Validate invalid TRANSFER tx
+    res = client.post(VALIDATE_ENDPOINT, data=json.dumps(
+        valid_transfer_transaction(None)))
+    assert res.json['valid'] == False
+    assert res.json['error'] == \
+        "ValueError('Only `CREATE` transactions can have null inputs',)"