From c993f954e088e3ccd88c156e8bab570286c1637e Mon Sep 17 00:00:00 2001
From: Scott Sadler <scott@alphanode.co>
Date: Mon, 27 Feb 2017 20:56:01 +0100
Subject: [PATCH] wip

---
 bigchaindb/core.py               | 25 ++++++++-----------------
 bigchaindb/models.py             |  6 ++++--
 tests/pipelines/test_election.py | 16 ++++++++--------
 tests/test_models.py             |  3 +--
 4 files changed, 21 insertions(+), 29 deletions(-)

diff --git a/bigchaindb/core.py b/bigchaindb/core.py
index e4419bb4..61ea5e8c 100644
--- a/bigchaindb/core.py
+++ b/bigchaindb/core.py
@@ -69,6 +69,9 @@ class Bigchain(object):
         if not self.me or not self.me_private:
             raise exceptions.KeypairNotFoundException()
 
+    federation = property(lambda self: set(self.nodes_except_me + [self.me]))
+    """ Set of federation member public keys """
+
     def write_transaction(self, signed_transaction):
         """Write the transaction to bigchain.
 
@@ -107,19 +110,8 @@ class Bigchain(object):
             dict: database response or None if no reassignment is possible
         """
 
-        if self.nodes_except_me:
-            try:
-                federation_nodes = self.nodes_except_me + [self.me]
-                index_current_assignee = federation_nodes.index(transaction['assignee'])
-                new_assignee = random.choice(federation_nodes[:index_current_assignee] +
-                                             federation_nodes[index_current_assignee + 1:])
-            except ValueError:
-                # current assignee not in federation
-                new_assignee = random.choice(self.nodes_except_me)
-
-        else:
-            # There is no other node to assign to
-            new_assignee = self.me
+        other_nodes = self.federation.difference([transaction['assignee']])
+        new_assignee = random.choice(other_nodes) if other_nodes else self.me
 
         return backend.query.update_transaction(
                 self.connection, transaction['id'],
@@ -467,7 +459,7 @@ class Bigchain(object):
             raise exceptions.OperationError('Empty block creation is not '
                                             'allowed')
 
-        voters = self.nodes_except_me + [self.me]
+        voters = list(self.federation)
         block = Block(validated_transactions, self.me, gen_timestamp(), voters)
         block = block.sign(self.me_private)
 
@@ -607,9 +599,8 @@ class Bigchain(object):
             block = block.to_dict()
         votes = list(backend.query.get_votes_by_block_id(self.connection,
                                                          block['id']))
-        keyring = self.nodes_except_me + [self.me]
-        result = self.consensus.voting.block_election(block, votes, keyring)
-        return result
+        return self.consensus.voting.block_election(block, votes,
+                                                    self.federation)
 
     def block_election_status(self, block):
         """Tally the votes on a block, and return the status:
diff --git a/bigchaindb/models.py b/bigchaindb/models.py
index ee7efe8f..2d16800f 100644
--- a/bigchaindb/models.py
+++ b/bigchaindb/models.py
@@ -236,10 +236,12 @@ class Block(object):
             InvalidSignature: If a Block's signature is invalid.
         """
         # Check if the block was created by a federation node
-        possible_voters = (bigchain.nodes_except_me + [bigchain.me])
-        if self.node_pubkey not in possible_voters:
+        if self.node_pubkey not in bigchain.federation:
             raise OperationError('Only federation nodes can create blocks')
 
+        if set(self.voters) != bigchain.federation:
+            raise OperationError('Block voters differs from server keyring')
+
         # Check that the signature is valid
         if not self.is_signature_valid():
             raise InvalidSignature('Invalid block signature')
diff --git a/tests/pipelines/test_election.py b/tests/pipelines/test_election.py
index bb01b6d1..e7491656 100644
--- a/tests/pipelines/test_election.py
+++ b/tests/pipelines/test_election.py
@@ -83,12 +83,6 @@ def test_check_for_quorum_invalid_prev_node(b, user_pk):
 def test_check_for_quorum_valid(b, user_pk):
     from bigchaindb.models import Transaction
 
-    e = election.Election()
-
-    # create blocks with transactions
-    tx1 = Transaction.create([b.me], [([user_pk], 1)])
-    test_block = b.create_block([tx1])
-
     # simulate a federation with four voters
     key_pairs = [crypto.generate_key_pair() for _ in range(4)]
     test_federation = [
@@ -96,10 +90,13 @@ def test_check_for_quorum_valid(b, user_pk):
         for key_pair in key_pairs
     ]
 
-    keyring = e.bigchain.nodes_except_me = [key_pair[1] for key_pair in key_pairs]
+    b.nodes_except_me = [key_pair[1] for key_pair in key_pairs]
+
+    # create blocks with transactions
+    tx1 = Transaction.create([b.me], [([user_pk], 1)])
+    test_block = b.create_block([tx1])
 
     # add voters to block and write
-    test_block.voters = keyring
     test_block = test_block.sign(b.me_private)
     b.write_block(test_block)
 
@@ -110,6 +107,9 @@ def test_check_for_quorum_valid(b, user_pk):
     for vote in votes:
         b.write_vote(vote)
 
+    e = election.Election()
+    e.bigchain = b
+
     # since this block is valid, should go nowhere
     assert e.check_for_quorum(votes[-1]) is None
 
diff --git a/tests/test_models.py b/tests/test_models.py
index 8de3a6c2..0b8be0b0 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -115,13 +115,12 @@ class TestBlockModel(object):
 
         transactions = [Transaction.create([b.me], [([b.me], 1)])]
         timestamp = gen_timestamp()
-        voters = ['Qaaa', 'Qbbb']
 
         block = {
             'timestamp': timestamp,
             'transactions': [tx.to_dict() for tx in transactions],
             'node_pubkey': b.me,
-            'voters': voters,
+            'voters': list(b.federation),
         }
 
         block_body = {