[test] P2P functional test for certain fingerprinting protections

Author: Jim Posen

test/functional/p2p-fingerprint.py

@@ -0,0 +1,158 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test various fingerprinting protections.
+
+If an stale block more than a month old or its header are requested by a peer,
+the node should pretend that it does not have it to avoid fingerprinting.
+"""
+
+import time
+
+from test_framework.blocktools import (create_block, create_coinbase)
+from test_framework.mininode import (
+    CInv,
+    NetworkThread,
+    NodeConn,
+    NodeConnCB,
+    msg_headers,
+    msg_block,
+    msg_getdata,
+    msg_getheaders,
+    wait_until,
+)
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    p2p_port,
+)
+
+class P2PFingerprintTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+
+    # Build a chain of blocks on top of given one
+    def build_chain(self, nblocks, prev_hash, prev_height, prev_median_time):
+        blocks = []
+        for _ in range(nblocks):
+            coinbase = create_coinbase(prev_height + 1)
+            block_time = prev_median_time + 1
+            block = create_block(int(prev_hash, 16), coinbase, block_time)
+            block.solve()
+
+            blocks.append(block)
+            prev_hash = block.hash
+            prev_height += 1
+            prev_median_time = block_time
+        return blocks
+
+    # Send a getdata request for a given block hash
+    def send_block_request(self, block_hash, node):
+        msg = msg_getdata()
+        msg.inv.append(CInv(2, block_hash))  # 2 == "Block"
+        node.send_message(msg)
+
+    # Send a getheaders request for a given single block hash
+    def send_header_request(self, block_hash, node):
+        msg = msg_getheaders()
+        msg.hashstop = block_hash
+        node.send_message(msg)
+
+    # Check whether last block received from node has a given hash
+    def last_block_equals(self, expected_hash, node):
+        block_msg = node.last_message.get("block")
+        return block_msg and block_msg.block.rehash() == expected_hash
+
+    # Check whether last block header received from node has a given hash
+    def last_header_equals(self, expected_hash, node):
+        headers_msg = node.last_message.get("headers")
+        return (headers_msg and
+                headers_msg.headers and
+                headers_msg.headers[0].rehash() == expected_hash)
+
+    # Checks that stale blocks timestamped more than a month ago are not served
+    # by the node while recent stale blocks and old active chain blocks are.
+    # This does not currently test that stale blocks timestamped within the
+    # last month but that have over a month's worth of work are also withheld.
+    def run_test(self):
+        node0 = NodeConnCB()
+
+        connections = []
+        connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], node0))
+        node0.add_connection(connections[0])
+
+        NetworkThread().start()
+        node0.wait_for_verack()
+
+        # Set node time to 60 days ago
+        self.nodes[0].setmocktime(int(time.time()) - 60 * 24 * 60 * 60)
+
+        # Generating a chain of 10 blocks
+        block_hashes = self.nodes[0].generate(nblocks=10)
+
+        # Create longer chain starting 2 blocks before current tip
+        height = len(block_hashes) - 2
+        block_hash = block_hashes[height - 1]
+        block_time = self.nodes[0].getblockheader(block_hash)["mediantime"] + 1
+        new_blocks = self.build_chain(5, block_hash, height, block_time)
+
+        # Force reorg to a longer chain
+        node0.send_message(msg_headers(new_blocks))
+        node0.wait_for_getdata()
+        for block in new_blocks:
+            node0.send_and_ping(msg_block(block))
+
+        # Check that reorg succeeded
+        assert_equal(self.nodes[0].getblockcount(), 13)
+
+        stale_hash = int(block_hashes[-1], 16)
+
+        # Check that getdata request for stale block succeeds
+        self.send_block_request(stale_hash, node0)
+        test_function = lambda: self.last_block_equals(stale_hash, node0)
+        wait_until(test_function, timeout=3)
+
+        # Check that getheader request for stale block header succeeds
+        self.send_header_request(stale_hash, node0)
+        test_function = lambda: self.last_header_equals(stale_hash, node0)
+        wait_until(test_function, timeout=3)
+
+        # Longest chain is extended so stale is much older than chain tip
+        self.nodes[0].setmocktime(0)
+        tip = self.nodes[0].generate(nblocks=1)[0]
+        assert_equal(self.nodes[0].getblockcount(), 14)
+
+        # Send getdata & getheaders to refresh last received getheader message
+        block_hash = int(tip, 16)
+        self.send_block_request(block_hash, node0)
+        self.send_header_request(block_hash, node0)
+        node0.sync_with_ping()
+
+        # Request for very old stale block should now fail
+        self.send_block_request(stale_hash, node0)
+        time.sleep(3)
+        assert not self.last_block_equals(stale_hash, node0)
+
+        # Request for very old stale block header should now fail
+        self.send_header_request(stale_hash, node0)
+        time.sleep(3)
+        assert not self.last_header_equals(stale_hash, node0)
+
+        # Verify we can fetch very old blocks and headers on the active chain
+        block_hash = int(block_hashes[2], 16)
+        self.send_block_request(block_hash, node0)
+        self.send_header_request(block_hash, node0)
+        node0.sync_with_ping()
+
+        self.send_block_request(block_hash, node0)
+        test_function = lambda: self.last_block_equals(block_hash, node0)
+        wait_until(test_function, timeout=3)
+
+        self.send_header_request(block_hash, node0)
+        test_function = lambda: self.last_header_equals(block_hash, node0)
+        wait_until(test_function, timeout=3)
+
+if __name__ == '__main__':
+    P2PFingerprintTest().main()

test/functional/test_framework/mininode.py

@@ -1310,8 +1310,8 @@ def __repr__(self):
 class msg_headers(object):
     command = b"headers"
 
-    def __init__(self):
-        self.headers = []
+    def __init__(self, headers=None):
+        self.headers = headers if headers is not None else []
 
     def deserialize(self, f):
         # comment in bitcoind indicates these should be deserialized as blocks

test/functional/test_runner.py

@@ -123,6 +123,7 @@
     'uptime.py',
     'resendwallettransactions.py',
     'minchainwork.py',
+    'p2p-fingerprint.py',
 ]
 
 EXTENDED_SCRIPTS = [