test: add test for chains building on invalid blocks

test/functional/p2p_invalid_chain.py

@@ -0,0 +1,105 @@
+#!/usr/bin/env python3
+# Copyright (c) 2024-present 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 how invalid blocks will influence chain behavior, in particular
+   the acceptance of future blocks and / or headers building on an invalid chain
+   For simplicity, submitheader / submitblock rpcs will be used in this test. The
+   behavior will be the same if blocks / headers are received through the p2p network.
+"""
+
+from test_framework.blocktools import (
+    create_block,
+    create_coinbase,
+)
+from test_framework.script import CScript
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
+
+
+class InvalidChainTest (BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def run_test(self):
+        node = self.nodes[0]
+        tip = int(node.getbestblockhash(), 16)
+        start_height = self.nodes[0].getblockcount()
+
+        self.log.info("Test chain with an invalid block (found invalid during connect)")
+        # Create invalid block (too high coinbase)
+        block_time = node.getblock(node.getbestblockhash())['time'] + 1
+        invalid_block = create_block(tip, create_coinbase(start_height + 1, nValue=100), block_time)
+        invalid_block.solve()
+        # Submit the valid header of the invalid block and a header that builds on it
+        node.submitheader(invalid_block.serialize().hex())
+        block_time += 1
+        block2a = create_block(invalid_block.sha256, create_coinbase(start_height + 2), block_time)
+        block2a.solve()
+        node.submitheader(block2a.serialize().hex())
+        # Submit the invalid block
+        assert_equal(node.submitblock(invalid_block.serialize().hex()), "bad-cb-amount")
+        # Submit a block building directly on the invalid block
+        block_time += 1
+        block2b = create_block(invalid_block.sha256, create_coinbase(start_height + 2), block_time)
+        block2b.solve()
+        assert_raises_rpc_error(-25, 'bad-prevblk', lambda: node.submitheader(block2b.serialize().hex()))
+        # Submit a block building indirectly on the invalid block
+        block_time += 1
+        block3 = create_block(block2a.sha256, create_coinbase(start_height + 3), block_time)
+        block3.solve()
+        assert_raises_rpc_error(-25, 'bad-prevblk', lambda: node.submitheader(block3.serialize().hex()))
+
+        self.log.info("Test chain with an invalid block (found invalid during acceptance)")
+        # Create invalid block (bad coinbase height)
+        block_time += 1
+        invalid_block = create_block(tip, create_coinbase(start_height + 100), block_time)
+        invalid_block.solve()
+        # Submit the valid header of the invalid block and a header that builds on it
+        node.submitheader(invalid_block.serialize().hex())
+        block_time += 1
+        block2a = create_block(invalid_block.sha256, create_coinbase(start_height + 2), block_time)
+        block2a.solve()
+        node.submitheader(block2a.serialize().hex())
+        # Submit the invalid block
+        assert_equal(node.submitblock(invalid_block.serialize().hex()), "bad-cb-height")
+        # Submit a block building directly on the invalid block
+        block_time += 1
+        block2b = create_block(invalid_block.sha256, create_coinbase(start_height + 2), block_time)
+        block2b.solve()
+        assert_raises_rpc_error(-25, 'bad-prevblk', lambda: node.submitheader(block2b.serialize().hex()))
+        # Submit a block building indirectly on the invalid block
+        block_time += 1
+        block3 = create_block(block2a.sha256, create_coinbase(start_height + 3), block_time)
+        block3.solve()
+        node.submitheader(block3.serialize().hex())  # No error, we accept more headers building on a block we have marked as invalid.
+
+        self.log.info("Test chain with an invalid block (found invalid before acceptance)")
+        # Create invalid block (too large)
+        block_time += 1
+        invalid_block = create_block(tip, create_coinbase(start_height + 1, extra_output_script=CScript([b'\x00' * 1000000])), block_time)
+        invalid_block.solve()
+        # Submit the valid header of the invalid block and a header that builds on it
+        node.submitheader(invalid_block.serialize().hex())
+        block_time += 1
+        block2a = create_block(invalid_block.sha256, create_coinbase(start_height + 2), block_time)
+        block2a.solve()
+        node.submitheader(block2a.serialize().hex())
+        # Submit a block building directly on the invalid block
+        block_time += 1
+        block2b = create_block(invalid_block.sha256, create_coinbase(start_height + 2), block_time)
+        block2b.solve()
+        node.submitheader(block2b.serialize().hex())  # No error, we don't mark the block permanently as invalid.
+        # Submit a block building indirectly on the invalid block
+        assert_equal(node.submitblock(invalid_block.serialize().hex()), "bad-blk-length")
+        block_time += 1
+        block3 = create_block(block2a.sha256, create_coinbase(start_height + 3), block_time)
+        block3.solve()
+        node.submitheader(block3.serialize().hex())  # No error, we don't mark the block permanently as invalid.
+
+
+if __name__ == '__main__':
+    InvalidChainTest(__file__).main()

test/functional/test_runner.py

@@ -262,6 +262,7 @@ BASE_SCRIPTS = [
     'p2p_invalid_block.py --v2transport',
     'p2p_invalid_tx.py --v1transport',
     'p2p_invalid_tx.py --v2transport',
+    'p2p_invalid_chain.py',
     'p2p_v2_transport.py',
     'p2p_v2_encrypted.py',
     'p2p_v2_misbehaving.py',