Include latest_block_height in lookup response (#627)

proto/squeak_server.proto

@@ -61,11 +61,14 @@ message GetSqueakReply {
 }
 
 message LookupSqueaksReply {
-    /// Hash of the squeak to get.
-    repeated bytes hashes = 1;
+    /// Height of the latest block.
+    int32 latest_block_height = 1;
 
     /// Hash of the squeak to get.
-    repeated string allowed_addresses = 2;
+    repeated bytes hashes = 2;
+
+    /// Hash of the squeak to get.
+    repeated string allowed_addresses = 3;
 }
 
 message GetOfferReply {

squeaknode/server/squeak_server_handler.py

@@ -43,7 +43,9 @@ class SqueakServerHandler(object):
             "Got number of allowed addresses from db: {}".format(
                 len(allowed_addresses))
         )
+        latest_block_height = self.squeak_controller.get_best_block_height()
         return squeak_server_pb2.LookupSqueaksReply(
+            latest_block_height=latest_block_height,
             hashes=hashes,
             allowed_addresses=allowed_addresses,
         )

squeaknode/sync/peer_task.py

@@ -39,7 +39,8 @@ class PeerSyncTask:
         hashes_to_download = set(remote_hashes) - set(local_hashes)
 
         # Download squeaks for the hashes
-        # TODO: catch exception downloading individual squeak
+        # TODO: catch exception downloading individual squeak.
+        # TODO: check if hash belongs to correct range after downloading.
         for hash in hashes_to_download:
             if self.peer_connection.stopped():
                 return
@@ -70,6 +71,11 @@ class PeerSyncTask:
             addresses, min_block, max_block)
         remote_hashes = lookup_result.hashes
         allowed_addresses = lookup_result.allowed_addresses
+        peer_latest_block = lookup_result.latest_block_height
+
+        max_block = min(max_block, peer_latest_block)
+        if max_block < min_block:
+            return
 
         # Get local hashes
         local_hashes = self._get_local_unlocked_hashes(