committee v4 forward compatibility patch

Author: gkaempfer

committee/committee/availability_gateway_client.py

@@ -31,6 +31,11 @@ def _send_request(self, send_method, uri, data=None):
             raise BadRequest(res.status_code, res.text)
         return res.text
 
+    async def order_tree_height(self) -> int:
+        uri = "/availability_gateway/order_tree_height"
+        answer = await self._send_request("GET", uri)
+        return int(answer)
+
     async def get_batch_data(self, batch_id: int) -> Optional[StateUpdate]:
         uri = f'/availability_gateway/get_batch_data?batch_id={batch_id}'
         answer = self._send_request('GET', uri)

committee/committee/committee.py

@@ -21,7 +21,7 @@
 from starkware.storage.merkle_tree import MerkleTree
 from starkware.storage.storage import Storage
 
-from .availability_gateway_client import AvailabilityGatewayClient
+from .availability_gateway_client import AvailabilityGatewayClient, BadRequest
 from .custom_validation import is_valid
 
 logger = logging.getLogger(__package__)
@@ -44,7 +44,8 @@ def deserialize(cls, data: bytes) -> 'CommitteeBatchInfo':
 
 class Committee:
     def __init__(self, config: dict, private_key: str, storage: Storage,
-                 merkle_storage: Storage, hash_func, availability_gateway):
+                 merkle_storage: Storage, hash_func,
+                 availability_gateway: AvailabilityGatewayClient):
         self.storage = storage
         self.merkle_storage = merkle_storage
         self.hash_func = hash_func
@@ -145,11 +146,43 @@ async def compute_order_root(storage):
         await self.storage.set_value(
             self.committee_batch_info_key(batch_id), batch_info.serialize())
 
+        # In StarkEx version 4.5, the height of the order tree has changed. For an old committee
+        # (i.e. a committee from version 4.0 or below) to work with a version 4.5 backend, the order
+        # tree height must be checked against the availability gateway, and possibly changed.
+        # If the configured height doesn't match the height sent in response from the availability
+        # gateway, assert that the order tree is not validated (self.validate_orders must be False
+        # to swap order tree heights, otherwise the computed order root is incorrect anyway) and
+        # that the new height is the expected height in version 4.5 (which is 251).
+        # This will work when the committee is not validating orders, because in that case, the root
+        # provided by the availability gateway is the correct root (of the height-251 tree), so when
+        # the committee blindly signs this root along with the correct height, the claim will be
+        # approved.
+        # This patch will be deleted in the version 4.5 committee.
+        logger.info("Trying to fetch trades height from the availability gateway")
+        # If the API of order_tree_height exist in the Availability Gateway use it. Otherwise,
+        # stick with the configured configured_trades_height (this can happen if the SE
+        # Availability Gateway is using an old SE version whcih don't have the
+        # order_tree_height API).
+        trades_height = self.orders_merkle_height
+        try:
+            trades_height = await self.availability_gateway.order_tree_height()
+            if self.orders_merkle_height != trades_height:
+                assert not validate_orders, (
+                    f"validate_orders is {validate_orders}, but configured trades height "
+                    f"{self.orders_merkle_height} is not equal to response from the availability "
+                    f"gateway ({trades_height}). This indicates that the root of the order "
+                    f"tree was computed incorrectly and the claim will not be approved by the "
+                    f"availability gateway, so there is no point in signing and sending the "
+                    f"signature."
+                )
+        except BadRequest:
+            pass
+
         logger.info(f'Signing batch with sequence number {batch_info.sequence_number}')
 
         availability_claim = hash_availability_claim(
             batch_info.vaults_root, self.vaults_merkle_height, batch_info.orders_root,
-            self.orders_merkle_height, batch_info.sequence_number)
+            trades_height, batch_info.sequence_number)
         signature = eth.Account._sign_hash(availability_claim, self.account.key).signature.hex()
         return signature, availability_claim.hex()
 
@@ -221,4 +254,4 @@ async def async_hash_func(x, y):
 
 
 if __name__ == '__main__':
-    sys.exit(asyncio.run(main()))
+    sys.exit(asyncio.run(main()))

committee/committee/committee_test.py

@@ -10,11 +10,22 @@
 from .committee import Committee
 
 
+ORDER_TREE_HEIGHT = 63
+
+
+class AvailabilityGatewayClientMock:
+    def __init__(self):
+        pass
+
+    async def order_tree_height(self) -> int:
+        return ORDER_TREE_HEIGHT
+
+
 @pytest.fixture
 def committee():
     config = {
         'VAULTS_MERKLE_HEIGHT': 31,
-        'ORDERS_MERKLE_HEIGHT': 63,
+        'ORDERS_MERKLE_HEIGHT': ORDER_TREE_HEIGHT,
         'POLLING_INTERVAL': 1,
     }
 
@@ -24,7 +35,7 @@ def committee():
         storage=MockStorage(),
         merkle_storage=MockStorage(),
         hash_func=async_pedersen_hash_func,
-        availability_gateway=None)
+        availability_gateway=AvailabilityGatewayClientMock())
 
 
 @pytest.fixture