Experimenting with two-party PSBT signing.

side-node/src/bitcoin/driver.rs

@@ -4,25 +4,13 @@ use tracing_subscriber::filter::EnvFilter;
 use tracing_subscriber::util::SubscriberInitExt;
 use tracing_subscriber::{fmt, layer::SubscriberExt};
 
+use super::clients::esplora::EsploraWallet;
+
 pub(crate) async fn simple_transfer() -> Result<(), anyhow::Error> {
-    tracing_setup();
-
-    let mut dave = clients::esplora::create_wallet("dave", Network::Signet)?;
-    let mut sammy = clients::esplora::create_wallet("sammy", Network::Signet)?;
-
-    let _next_address = dave.next_unused_address()?;
-
-    let _ = dave.balance();
-    dave.sync().await?;
-    let _ = dave.balance();
-
-    let _sammy = sammy.balance();
-    sammy.sync().await?;
-    let _ = sammy.balance();
-
+    let (mut dave, mut sammy) = setup().await?;
 
     let send_amount = Amount::from_sat(500);
-   ensure_enough_sats(dave, send_amount);
+    ensure_enough_sats(&dave, send_amount);
 
     let sammy_address = sammy.next_unused_address()?.address;
     let tx = dave.build_and_sign_send_tx(sammy_address, send_amount)?;
@@ -31,8 +19,21 @@ pub(crate) async fn simple_transfer() -> Result<(), anyhow::Error> {
     Ok(())
 }
 
+async fn setup() -> Result<(EsploraWallet, EsploraWallet), anyhow::Error> {
+    tracing_setup();
+    let mut dave = clients::esplora::create_wallet("dave", Network::Signet)?;
+    let mut sammy = clients::esplora::create_wallet("sammy", Network::Signet)?;
+    let _ = dave.balance();
+    dave.sync().await?;
+    let _ = dave.balance();
+    let _sammy = sammy.balance();
+    sammy.sync().await?;
+    let _ = sammy.balance();
+    Ok((dave, sammy))
+}
+
 /// Exit if the wallet does not have enough sats to send.
-fn ensure_enough_sats(wallet: EsploraWallet, send_amount: bitcoin::Amount) -> _ {
+fn ensure_enough_sats(wallet: &EsploraWallet, send_amount: bitcoin::Amount) {
     if wallet.balance().total() < send_amount {
         tracing::error!(
             "Please send at least {} sats to the receiving address. Exiting.",
@@ -43,12 +44,38 @@ fn ensure_enough_sats(wallet: EsploraWallet, send_amount: bitcoin::Amount) -> _
 }
 
 pub(crate) async fn htlc() -> anyhow::Result<()> {
-    // dave will be our sender
-    let mut dave = clients::esplora::create_wallet("dave", Network::Signet)?;
+    let (mut dave, mut sammy) = setup().await?;
 
-    // sammy will be our liquidity router
-    let mut sammy = clients::esplora::create_wallet("sammy", Network::Signet)?;
+    // format a new commitment transaction like in Lightning
+    let mut commitment_builder = dave.build_tx()?;
+    let amount = Amount::from_sat(500);
+    let recipient = sammy.next_unused_address()?.script_pubkey();
+    commitment_builder.add_recipient(recipient, amount);
+    commitment_builder.enable_rbf();
+    let psbt = commitment_builder
+        .finish()
+        .expect("unable to build commitment");
 
+    // sign the commitment transaction
+    let mut dave_psbt = dave.sign(&mut psbt.clone(), false)?;
+    let sammy_psbt = sammy.sign(&mut psbt.clone(), false)?;
+
+    dave_psbt
+        .combine(sammy_psbt)
+        .expect("problem combining bitcoin PSBTs"); // these guys love mutability
+
+    let finalized = dave
+        .wallet()
+        .finalize_psbt(&mut dave_psbt, bdk_wallet::SignOptions::default())
+        .expect("couldn't finalize");
+
+    assert!(finalized);
+    let tx = dave_psbt.extract_tx()?;
+
+    let _ = dave.broadcast(&tx).await.expect("couldn't broadcast");
+
+    let _ = sammy.sync();
+    sammy.balance();
     Ok(())
 }