+impl SpendableOutputDescriptor {
+ /// Turns this into a [`bitcoin::psbt::Input`] which can be used to create a
+ /// [`PartiallySignedTransaction`] which spends the given descriptor.
+ ///
+ /// Note that this does not include any signatures, just the information required to
+ /// construct the transaction and sign it.
+ pub fn to_psbt_input(&self) -> bitcoin::psbt::Input {
+ match self {
+ SpendableOutputDescriptor::StaticOutput { output, .. } => {
+ // Is a standard P2WPKH, no need for witness script
+ bitcoin::psbt::Input {
+ witness_utxo: Some(output.clone()),
+ ..Default::default()
+ }
+ },
+ SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
+ // TODO we could add the witness script as well
+ bitcoin::psbt::Input {
+ witness_utxo: Some(descriptor.output.clone()),
+ ..Default::default()
+ }
+ },
+ SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
+ // TODO we could add the witness script as well
+ bitcoin::psbt::Input {
+ witness_utxo: Some(descriptor.output.clone()),
+ ..Default::default()
+ }
+ },
+ }
+ }
+
+ /// Creates an unsigned [`PartiallySignedTransaction`] which spends the given descriptors to
+ /// the given outputs, plus an output to the given change destination (if sufficient
+ /// change value remains). The PSBT will have a feerate, at least, of the given value.
+ ///
+ /// The `locktime` argument is used to set the transaction's locktime. If `None`, the
+ /// transaction will have a locktime of 0. It it recommended to set this to the current block
+ /// height to avoid fee sniping, unless you have some specific reason to use a different
+ /// locktime.
+ ///
+ /// Returns the PSBT and expected max transaction weight.
+ ///
+ /// Returns `Err(())` if the output value is greater than the input value minus required fee,
+ /// if a descriptor was duplicated, or if an output descriptor `script_pubkey`
+ /// does not match the one we can spend.
+ ///
+ /// We do not enforce that outputs meet the dust limit or that any output scripts are standard.
+ pub fn create_spendable_outputs_psbt(descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>, change_destination_script: Script, feerate_sat_per_1000_weight: u32, locktime: Option<PackedLockTime>) -> Result<(PartiallySignedTransaction, usize), ()> {
+ let mut input = Vec::with_capacity(descriptors.len());
+ let mut input_value = 0;
+ let mut witness_weight = 0;
+ let mut output_set = HashSet::with_capacity(descriptors.len());
+ for outp in descriptors {
+ match outp {
+ SpendableOutputDescriptor::StaticPaymentOutput(descriptor) => {
+ if !output_set.insert(descriptor.outpoint) { return Err(()); }
+ let sequence =
+ if descriptor.channel_transaction_parameters.as_ref()
+ .map(|channel_params| channel_params.channel_type_features.supports_anchors_zero_fee_htlc_tx())
+ .unwrap_or(false)
+ {
+ Sequence::from_consensus(1)
+ } else {
+ Sequence::ZERO
+ };
+ input.push(TxIn {
+ previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
+ script_sig: Script::new(),
+ sequence,
+ witness: Witness::new(),
+ });
+ witness_weight += descriptor.max_witness_length();
+ #[cfg(feature = "grind_signatures")]
+ { witness_weight -= 1; } // Guarantees a low R signature
+ input_value += descriptor.output.value;
+ },
+ SpendableOutputDescriptor::DelayedPaymentOutput(descriptor) => {
+ if !output_set.insert(descriptor.outpoint) { return Err(()); }
+ input.push(TxIn {
+ previous_output: descriptor.outpoint.into_bitcoin_outpoint(),
+ script_sig: Script::new(),
+ sequence: Sequence(descriptor.to_self_delay as u32),
+ witness: Witness::new(),
+ });
+ witness_weight += DelayedPaymentOutputDescriptor::MAX_WITNESS_LENGTH;
+ #[cfg(feature = "grind_signatures")]
+ { witness_weight -= 1; } // Guarantees a low R signature
+ input_value += descriptor.output.value;
+ },
+ SpendableOutputDescriptor::StaticOutput { ref outpoint, ref output } => {
+ if !output_set.insert(*outpoint) { return Err(()); }
+ input.push(TxIn {
+ previous_output: outpoint.into_bitcoin_outpoint(),
+ script_sig: Script::new(),
+ sequence: Sequence::ZERO,
+ witness: Witness::new(),
+ });
+ witness_weight += 1 + 73 + 34;
+ #[cfg(feature = "grind_signatures")]
+ { witness_weight -= 1; } // Guarantees a low R signature
+ input_value += output.value;
+ }
+ }
+ if input_value > MAX_VALUE_MSAT / 1000 { return Err(()); }
+ }
+ let mut tx = Transaction {
+ version: 2,
+ lock_time: locktime.unwrap_or(PackedLockTime::ZERO),
+ input,
+ output: outputs,
+ };
+ let expected_max_weight =
+ transaction_utils::maybe_add_change_output(&mut tx, input_value, witness_weight, feerate_sat_per_1000_weight, change_destination_script)?;
+
+ let psbt_inputs = descriptors.iter().map(|d| d.to_psbt_input()).collect::<Vec<_>>();
+ let psbt = PartiallySignedTransaction {
+ inputs: psbt_inputs,
+ outputs: vec![Default::default(); tx.output.len()],
+ unsigned_tx: tx,
+ xpub: Default::default(),
+ version: 0,
+ proprietary: Default::default(),
+ unknown: Default::default(),
+ };
+ Ok((psbt, expected_max_weight))
+ }
+}
+