Fix spurious panic on bogus funding txn that confirm and are spent

[rust-lightning] / lightning / src / ln / functional_tests.rs

diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs
index c304161947af34c31ceed9d28eadad51148191f6..9ecbee739f1874eaa0b8cbfca4d19ff7658b5e90 100644 (file)
--- a/lightning/src/ln/functional_tests.rs
+++ b/lightning/src/ln/functional_tests.rs
@@ -37,7 +37,7 @@ use util::config::UserConfig;
 
 use bitcoin::hash_types::BlockHash;
 use bitcoin::blockdata::block::{Block, BlockHeader};
-use bitcoin::blockdata::script::Builder;
+use bitcoin::blockdata::script::{Builder, Script};
 use bitcoin::blockdata::opcodes;
 use bitcoin::blockdata::constants::genesis_block;
 use bitcoin::network::constants::Network;
@@ -9424,6 +9424,10 @@ fn test_invalid_funding_tx() {
        // funding transactions from their counterparties, leading to a multi-implementation critical
        // security vulnerability (though we always sanitized properly, we've previously had
        // un-released crashes in the sanitization process).
+       //
+       // Further, if the funding transaction is consensus-valid, confirms, and is later spent, we'd
+       // previously have crashed in `ChannelMonitor` even though we closed the channel as bogus and
+       // gave up on it. We test this here by generating such a transaction.
        let chanmon_cfgs = create_chanmon_cfgs(2);
        let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
        let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
@@ -9434,9 +9438,19 @@ fn test_invalid_funding_tx() {
        nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), InitFeatures::known(), &get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id()));
 
        let (temporary_channel_id, mut tx, _) = create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 100_000, 42);
+
+       // Create a witness program which can be spent by a 4-empty-stack-elements witness and which is
+       // 136 bytes long. This matches our "accepted HTLC preimage spend" matching, previously causing
+       // a panic as we'd try to extract a 32 byte preimage from a witness element without checking
+       // its length.
+       let mut wit_program: Vec<u8> = channelmonitor::deliberately_bogus_accepted_htlc_witness_program();
+       assert!(chan_utils::HTLCType::scriptlen_to_htlctype(wit_program.len()).unwrap() ==
+               chan_utils::HTLCType::AcceptedHTLC);
+
+       let wit_program_script: Script = wit_program.clone().into();
        for output in tx.output.iter_mut() {
                // Make the confirmed funding transaction have a bogus script_pubkey
-               output.script_pubkey = bitcoin::Script::new();
+               output.script_pubkey = Script::new_v0_p2wsh(&wit_program_script.wscript_hash());
        }
 
        nodes[0].node.funding_transaction_generated_unchecked(&temporary_channel_id, &nodes[1].node.get_our_node_id(), tx.clone(), 0).unwrap();
@@ -9466,6 +9480,28 @@ fn test_invalid_funding_tx() {
                } else { panic!(); }
        } else { panic!(); }
        assert_eq!(nodes[1].node.list_channels().len(), 0);
+
+       // Now confirm a spend of the (bogus) funding transaction. As long as the witness is 5 elements
+       // long the ChannelMonitor will try to read 32 bytes from the second-to-last element, panicing
+       // as its not 32 bytes long.
+       let mut spend_tx = Transaction {
+               version: 2i32, lock_time: 0,
+               input: tx.output.iter().enumerate().map(|(idx, _)| TxIn {
+                       previous_output: BitcoinOutPoint {
+                               txid: tx.txid(),
+                               vout: idx as u32,
+                       },
+                       script_sig: Script::new(),
+                       sequence: 0xfffffffd,
+                       witness: Witness::from_vec(channelmonitor::deliberately_bogus_accepted_htlc_witness())
+               }).collect(),
+               output: vec![TxOut {
+                       value: 1000,
+                       script_pubkey: Script::new(),
+               }]
+       };
+       check_spends!(spend_tx, tx);
+       mine_transaction(&nodes[1], &spend_tx);
 }
 
 fn do_test_tx_confirmed_skipping_blocks_immediate_broadcast(test_height_before_timelock: bool) {