Use ln OutPoints not bitcoin ones in SpendableOutputDescriptors

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

diff --git a/lightning/src/ln/channelmonitor.rs b/lightning/src/ln/channelmonitor.rs
index c743f647ccdeb0849aa5abce2771c807788a3b4e..570982fb70c280de5637adedafccced787bcaacb 100644 (file)
--- a/lightning/src/ln/channelmonitor.rs
+++ b/lightning/src/ln/channelmonitor.rs
@@ -2201,16 +2201,30 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        fn is_paying_spendable_output<L: Deref>(&mut self, tx: &Transaction, height: u32, logger: &L) where L::Target: Logger {
                let mut spendable_output = None;
                for (i, outp) in tx.output.iter().enumerate() { // There is max one spendable output for any channel tx, including ones generated by us
+                       if i > ::std::u16::MAX as usize {
+                               // While it is possible that an output exists on chain which is greater than the
+                               // 2^16th output in a given transaction, this is only possible if the output is not
+                               // in a lightning transaction and was instead placed there by some third party who
+                               // wishes to give us money for no reason.
+                               // Namely, any lightning transactions which we pre-sign will never have anywhere
+                               // near 2^16 outputs both because such transactions must have ~2^16 outputs who's
+                               // scripts are not longer than one byte in length and because they are inherently
+                               // non-standard due to their size.
+                               // Thus, it is completely safe to ignore such outputs, and while it may result in
+                               // us ignoring non-lightning fund to us, that is only possible if someone fills
+                               // nearly a full block with garbage just to hit this case.
+                               continue;
+                       }
                        if outp.script_pubkey == self.destination_script {
                                spendable_output =  Some(SpendableOutputDescriptor::StaticOutput {
-                                       outpoint: BitcoinOutPoint { txid: tx.txid(), vout: i as u32 },
+                                       outpoint: OutPoint { txid: tx.txid(), index: i as u16 },
                                        output: outp.clone(),
                                });
                                break;
                        } else if let Some(ref broadcasted_local_revokable_script) = self.broadcasted_local_revokable_script {
                                if broadcasted_local_revokable_script.0 == outp.script_pubkey {
                                        spendable_output =  Some(SpendableOutputDescriptor::DynamicOutputP2WSH {
-                                               outpoint: BitcoinOutPoint { txid: tx.txid(), vout: i as u32 },
+                                               outpoint: OutPoint { txid: tx.txid(), index: i as u16 },
                                                per_commitment_point: broadcasted_local_revokable_script.1,
                                                to_self_delay: self.on_local_tx_csv,
                                                output: outp.clone(),
@@ -2221,14 +2235,14 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                                }
                        } else if self.remote_payment_script == outp.script_pubkey {
                                spendable_output = Some(SpendableOutputDescriptor::StaticOutputRemotePayment {
-                                       outpoint: BitcoinOutPoint { txid: tx.txid(), vout: i as u32 },
+                                       outpoint: OutPoint { txid: tx.txid(), index: i as u16 },
                                        output: outp.clone(),
                                        key_derivation_params: self.keys.key_derivation_params(),
                                });
                                break;
                        } else if outp.script_pubkey == self.shutdown_script {
                                spendable_output = Some(SpendableOutputDescriptor::StaticOutput {
-                                       outpoint: BitcoinOutPoint { txid: tx.txid(), vout: i as u32 },
+                                       outpoint: OutPoint { txid: tx.txid(), index: i as u16 },
                                        output: outp.clone(),
                                });
                        }