diff --git a/src/net_processing.cpp b/src/net_processing.cpp --- a/src/net_processing.cpp +++ b/src/net_processing.cpp @@ -4563,12 +4563,29 @@ return; } + if (fImporting || fReindex) { + LogPrint( + BCLog::NET, + "Ignoring getheaders from peer=%d while importing/reindexing\n", + pfrom.GetId()); + return; + } + LOCK(cs_main); - if (m_chainman.ActiveChainstate().IsInitialBlockDownload() && - !pfrom.HasPermission(NetPermissionFlags::Download)) { + + // Note that if we were to be on a chain that forks from the + // checkpointed chain, then serving those headers to a peer that has + // seen the checkpointed chain would cause that peer to disconnect us. + // Requiring that our chainwork exceed nMinimumChainWork is a protection + // against being fed a bogus chain when we started up for the first time + // and getting partitioned off the honest network for serving that chain + // to others. + if (m_chainman.ActiveTip() == nullptr || + (m_chainman.ActiveTip()->nChainWork < nMinimumChainWork && + !pfrom.HasPermission(NetPermissionFlags::Download))) { LogPrint(BCLog::NET, - "Ignoring getheaders from peer=%d because node is in " - "initial block download\n", + "Ignoring getheaders from peer=%d because active chain " + "has too little work\n", pfrom.GetId()); return; } diff --git a/test/functional/feature_minchainwork.py b/test/functional/feature_minchainwork.py --- a/test/functional/feature_minchainwork.py +++ b/test/functional/feature_minchainwork.py @@ -17,6 +17,7 @@ import time +from test_framework.p2p import P2PInterface, msg_getheaders from test_framework.test_framework import BitcoinTestFramework from test_framework.util import assert_equal @@ -41,6 +42,9 @@ for i in range(self.num_nodes - 1): self.connect_nodes(i + 1, i) + # Set clock of node2 2 days ahead, to keep it in IBD during this test. + self.nodes[2].setmocktime(int(time.time()) + 48 * 60 * 60) + def run_test(self): # Start building a chain on node0. node2 shouldn't be able to sync until node1's # minchainwork is exceeded @@ -80,6 +84,15 @@ assert self.nodes[1].getbestblockhash() != self.nodes[0].getbestblockhash() assert_equal(self.nodes[2].getblockcount(), starting_blockcount) + self.log.info("Check that getheaders requests to node2 are ignored") + peer = self.nodes[2].add_p2p_connection(P2PInterface()) + msg = msg_getheaders() + msg.locator.vHave = [int(self.nodes[2].getbestblockhash(), 16)] + msg.hashstop = 0 + peer.send_and_ping(msg) + time.sleep(5) + assert "headers" not in peer.last_message + self.log.info("Generating one more block") self.generate(self.nodes[0], 1) @@ -94,6 +107,14 @@ self.sync_all() self.log.info(f"Blockcounts: {[n.getblockcount() for n in self.nodes]}") + self.log.info("Test that getheaders requests to node2 are not ignored") + peer.send_and_ping(msg) + assert "headers" in peer.last_message + + # Verify that node2 is in fact still in IBD (otherwise this test may + # not be exercising the logic we want!) + assert_equal(self.nodes[2].getblockchaininfo()["initialblockdownload"], True) + if __name__ == "__main__": MinimumChainWorkTest().main()