Implement mining task request/response

node.py

@@ -360,6 +360,37 @@ def receiver(node, b):
             }
             identifier = (addr[0:2], "transaction")
             receive_observer.publish(identifier, event_obj)
+        elif msg_type == 7:
+            # mining task request
+            if msg_len != 225:
+                log(f"Got a mining task request of wrong length ({msg_len} bytes from {sender}, but expected 255 bytes)")
+                continue
+            transaction = b.open_transactions.get_transaction(0)
+            if transaction is not None:
+                transaction_raw = transaction.get_transaction_raw()
+            else:
+                transaction_raw = 148 * b"\0"
+            t = int(time.time())
+            timestamp_raw = t.to_bytes(8, "big")
+            latest_block = b.get_latest_block()
+            if latest_block is not None:
+                B_1_difficulty_sum, _ = latest_block.get_difficulty_info(0, blockchain)
+                B_10_difficulty_sum, B_10_timestamp = latest_block.get_difficulty_info(9, blockchain)
+                D = B_1_difficulty_sum - B_10_difficulty_sum
+                T = t - B_10_timestamp
+                calculated_difficulty = D * 3000 // 9 // T
+                block_difficulty = max(calculated_difficulty, 2**28)
+                difficulty_sum = B_1_difficulty_sum + block_difficulty
+                previous_hash = latest_block.own_hash
+            else:
+                difficulty_sum = 2**29
+                previous_hash = 32 * b"\0"
+            response = b"\0\0\0\0\x08" + \
+                transaction_raw + \
+                previous_hash + \
+                timestamp_raw + \
+                difficulty_sum.to_bytes(32, "big")
+            node.node_socket.sendto(response, addr)
         elif msg_type == 9:
             # payment request
             if msg_len != 153: