Late locking (experimental) (#530)

* Late locking (experimental)

* Error on fee change

* Improve comments

* Fix typo in comment

* Add late locking flag to CLI command

libwallet/src/api_impl/foreign.rs

@@ -105,6 +105,9 @@ where
 		use_test_rng,
 	)?;
 
+	// Add our contribution to the offset
+	ret_slate.adjust_offset(&keychain, &context)?;
+
 	let excess = ret_slate.calc_excess(keychain.secp())?;
 
 	if let Some(ref mut p) = ret_slate.payment_proof {
@@ -143,6 +146,9 @@ where
 	if sl.state == SlateState::Invoice2 {
 		check_ttl(w, &sl)?;
 
+		// Add our contribution to the offset
+		sl.adjust_offset(&w.keychain(keychain_mask)?, &context)?;
+
 		let mut temp_ctx = context.clone();
 		temp_ctx.sec_key = context.initial_sec_key.clone();
 		temp_ctx.sec_nonce = context.initial_sec_nonce.clone();

libwallet/src/api_impl/owner.rs

@@ -457,9 +457,9 @@ where
 	C: NodeClient + 'a,
 	K: Keychain + 'a,
 {
-	let parent_key_id = match args.src_acct_name {
+	let parent_key_id = match &args.src_acct_name {
 		Some(d) => {
-			let pm = w.get_acct_path(d)?;
+			let pm = w.get_acct_path(d.clone())?;
 			match pm {
 				Some(p) => p.path,
 				None => w.parent_key_id(),
@@ -500,19 +500,31 @@ where
 	}
 
 	let height = w.w2n_client().get_chain_tip()?.0;
-	let mut context = tx::add_inputs_to_slate(
-		&mut *w,
-		keychain_mask,
-		&mut slate,
-		height,
-		args.minimum_confirmations,
-		args.max_outputs as usize,
-		args.num_change_outputs as usize,
-		args.selection_strategy_is_use_all,
-		&parent_key_id,
-		true,
-		use_test_rng,
-	)?;
+	let mut context = if args.late_lock.unwrap_or(false) {
+		tx::create_late_lock_context(
+			&mut *w,
+			keychain_mask,
+			&mut slate,
+			height,
+			&args,
+			&parent_key_id,
+			use_test_rng,
+		)?
+	} else {
+		tx::add_inputs_to_slate(
+			&mut *w,
+			keychain_mask,
+			&mut slate,
+			height,
+			args.minimum_confirmations,
+			args.max_outputs as usize,
+			args.num_change_outputs as usize,
+			args.selection_strategy_is_use_all,
+			&parent_key_id,
+			true,
+			use_test_rng,
+		)?
+	};
 
 	// Payment Proof, add addresses to slate and save address
 	// TODO: Note we only use single derivation path for now,
@@ -667,6 +679,19 @@ where
 	)?;
 
 	let keychain = w.keychain(keychain_mask)?;
+
+	// Add our contribution to the offset
+	if context_res.is_ok() {
+		// Self sending: don't correct for inputs and outputs
+		// here, as we will do it during finalization.
+		let mut tmp_context = context.clone();
+		tmp_context.input_ids.clear();
+		tmp_context.output_ids.clear();
+		ret_slate.adjust_offset(&keychain, &tmp_context)?;
+	} else {
+		ret_slate.adjust_offset(&keychain, &context)?;
+	}
+
 	// needs to be stored as we're removing sig data for return trip. this needs to be present
 	// when locking transaction context and updating tx log with excess later
 	context.calculated_excess = Some(ret_slate.calc_excess(keychain.secp())?);
@@ -685,7 +710,6 @@ where
 		}
 	}
 
-	tx::sub_inputs_from_offset(&mut *w, keychain_mask, &context, &mut ret_slate)?;
 	selection::repopulate_tx(&mut *w, keychain_mask, &mut ret_slate, &context, false)?;
 
 	// Save the aggsig context in our DB for when we
@@ -754,16 +778,51 @@ where
 {
 	let mut sl = slate.clone();
 	check_ttl(w, &sl)?;
-	let context = w.get_private_context(keychain_mask, sl.id.as_bytes())?;
+	let mut context = w.get_private_context(keychain_mask, sl.id.as_bytes())?;
+	let keychain = w.keychain(keychain_mask)?;
 	let parent_key_id = w.parent_key_id();
 
-	// since we're now actually inserting our inputs, pick an offset and adjust
-	// our contribution to the excess by offset amount
-	// TODO: Post HF3, this should allow for inputs to be picked at this stage
-	// as opposed to locking them prior to this stage, as the excess to this point
-	// will just be the change output
+	if let Some(args) = context.late_lock_args.take() {
+		// Transaction was late locked, select inputs+change now
+		// and insert into original context
+
+		let current_height = w.w2n_client().get_chain_tip()?.0;
+		let mut temp_sl =
+			tx::new_tx_slate(&mut *w, context.amount, false, 2, false, args.ttl_blocks)?;
+		let temp_context = selection::build_send_tx(
+			w,
+			&keychain,
+			keychain_mask,
+			&mut temp_sl,
+			current_height,
+			args.minimum_confirmations,
+			args.max_outputs as usize,
+			args.num_change_outputs as usize,
+			args.selection_strategy_is_use_all,
+			Some(context.fee),
+			parent_key_id.clone(),
+			false,
+			true,
+		)?;
+
+		// Add inputs and outputs to original context
+		context.input_ids = temp_context.input_ids;
+		context.output_ids = temp_context.output_ids;
+
+		// Store the updated context
+		{
+			let mut batch = w.batch(keychain_mask)?;
+			batch.save_private_context(sl.id.as_bytes(), &context)?;
+			batch.commit()?;
+		}
+
+		// Now do the actual locking
+		tx_lock_outputs(w, keychain_mask, &sl)?;
+	}
+
+	// Add our contribution to the offset
+	sl.adjust_offset(&keychain, &context)?;
 
-	tx::sub_inputs_from_offset(&mut *w, keychain_mask, &context, &mut sl)?;
 	selection::repopulate_tx(&mut *w, keychain_mask, &mut sl, &context, true)?;
 
 	tx::complete_tx(&mut *w, keychain_mask, &mut sl, &context)?;

libwallet/src/api_impl/types.rs

@@ -25,7 +25,7 @@ use crate::SlatepackAddress;
 use ed25519_dalek::Signature as DalekSignature;
 
 /// V2 Init / Send TX API Args
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct InitTxArgs {
 	/// The human readable account name from which to draw outputs
 	/// for the transaction, overriding whatever the active account is as set via the
@@ -71,6 +71,10 @@ pub struct InitTxArgs {
 	/// 'true', the amount field in the slate will contain the total amount locked, not the provided
 	/// transaction amount
 	pub estimate_only: Option<bool>,
+	/// EXPERIMENTAL: if flagged, create the transaction as late-locked, i.e. don't select actual
+	/// inputs until just before finalization
+	#[serde(default)]
+	pub late_lock: Option<bool>,
 	/// Sender arguments. If present, the underlying function will also attempt to send the
 	/// transaction to a destination and optionally finalize the result
 	pub send_args: Option<InitTxSendArgs>,
@@ -78,7 +82,7 @@ pub struct InitTxArgs {
 
 /// Send TX API Args, for convenience functionality that inits the transaction and sends
 /// in one go
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct InitTxSendArgs {
 	/// The destination, contents will depend on the particular method
 	pub dest: String,
@@ -103,6 +107,7 @@ impl Default for InitTxArgs {
 			ttl_blocks: None,
 			estimate_only: Some(false),
 			payment_proof_recipient_address: None,
+			late_lock: Some(false),
 			send_args: None,
 		}
 	}