Introduce RecipientInfo struct for send_payment

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())

fuzz/src/chanmon_consistency.rs

@@ -35,7 +35,7 @@ use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
 use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
-use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
+use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret, RecipientInfo};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
 use lightning::ln::channel::FEE_SPIKE_BUFFER_FEE_INCREASE_MULTIPLE;
 use lightning::ln::features::{ChannelFeatures, InitFeatures, NodeFeatures};
@@ -301,6 +301,7 @@ fn get_payment_secret_hash(dest: &ChanMan, payment_id: &mut u8) -> Option<(Payme
 fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: dest.get_our_node_id(),
@@ -311,7 +312,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }
@@ -320,6 +321,7 @@ fn send_payment(source: &ChanMan, dest: &ChanMan, dest_chan_id: u64, amt: u64, p
 fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, dest: &ChanMan, dest_chan_id: u64, amt: u64, payment_id: &mut u8) -> bool {
 	let (payment_secret, payment_hash) =
  if let Some((secret, hash)) = get_payment_secret_hash(dest, payment_id) { (secret, hash) } else { return true; };
+	let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
 	if let Err(err) = source.send_payment(&Route {
  paths: vec![vec![RouteHop {
  pubkey: middle.get_our_node_id(),
@@ -337,7 +339,7 @@ fn send_hop_payment(source: &ChanMan, middle: &ChanMan, middle_chan_id: u64, des
  cltv_expiry_delta: 200,
  }]],
  payment_params: None,
-	}, payment_hash, &Some(payment_secret)) {
+	}, payment_hash, &recipient_info) {
  check_payment_err(err);
  false
 	} else { true }

fuzz/src/full_stack.rs

@@ -498,7 +498,8 @@ pub fn do_test(data: &[u8], logger: &Arc<dyn Logger>) {
  let mut payment_secret = PaymentSecret([0; 32]);
  payment_secret.0[0..8].copy_from_slice(&be64_to_array(payments_sent));
  payments_sent += 1;
- match channelmanager.send_payment(&route, payment_hash, &Some(payment_secret)) {
+ let recipient_info = RecipientInfo { payment_secret: Some(payment_secret), payment_metadata: None };
+ match channelmanager.send_payment(&route, payment_hash, &recipient_info) {
  Ok(_) => {},
  Err(_) => return,
  }

lightning-invoice/src/de.rs

@@ -459,6 +459,8 @@ impl FromBase32 for TaggedField {
  Ok(TaggedField::PrivateRoute(PrivateRoute::from_base32(field_data)?)),
  constants::TAG_PAYMENT_SECRET =>
  Ok(TaggedField::PaymentSecret(PaymentSecret::from_base32(field_data)?)),
+ constants::TAG_PAYMENT_METADATA =>
+ Ok(TaggedField::PaymentMetadata(Vec::<u8>::from_base32(field_data)?)),
  constants::TAG_FEATURES =>
  Ok(TaggedField::Features(InvoiceFeatures::from_base32(field_data)?)),
  _ => {

lightning-invoice/src/lib.rs

@@ -205,10 +205,13 @@ pub const DEFAULT_MIN_FINAL_CLTV_EXPIRY: u64 = 18;
 /// * `D`: exactly one `Description` or `DescriptionHash`
 /// * `H`: exactly one `PaymentHash`
 /// * `T`: the timestamp is set
+/// * `C`: the CLTV expiry is set
+/// * `S`: the payment secret is set
+/// * `M`: payment metadata is set
 ///
 /// (C-not exported) as we likely need to manually select one set of boolean type parameters.
 #[derive(Eq, PartialEq, Debug, Clone)]
-pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> {
+pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> {
 	currency: Currency,
 	amount: Option<u64>,
 	si_prefix: Option<SiPrefix>,
@@ -221,6 +224,7 @@ pub struct InvoiceBuilder<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S:
 	phantom_t: core::marker::PhantomData<T>,
 	phantom_c: core::marker::PhantomData<C>,
 	phantom_s: core::marker::PhantomData<S>,
+	phantom_m: core::marker::PhantomData<M>,
 }
 
 /// Represents a syntactically and semantically correct lightning BOLT11 invoice.
@@ -404,6 +408,7 @@ pub enum TaggedField {
 	Fallback(Fallback),
 	PrivateRoute(PrivateRoute),
 	PaymentSecret(PaymentSecret),
+	PaymentMetadata(Vec<u8>),
 	Features(InvoiceFeatures),
 }
 
@@ -469,10 +474,11 @@ pub mod constants {
 	pub const TAG_FALLBACK: u8 = 9;
 	pub const TAG_PRIVATE_ROUTE: u8 = 3;
 	pub const TAG_PAYMENT_SECRET: u8 = 16;
+	pub const TAG_PAYMENT_METADATA: u8 = 27;
 	pub const TAG_FEATURES: u8 = 5;
 }
 
-impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
+impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::False> {
 	/// Construct new, empty `InvoiceBuilder`. All necessary fields have to be filled first before
 	/// `InvoiceBuilder::build(self)` becomes available.
 	pub fn new(currrency: Currency) -> Self {
@@ -489,14 +495,15 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False> {
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, S, M> {
 	/// Helper function to set the completeness flags.
-	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN> {
- InvoiceBuilder::<DN, HN, TN, CN, SN> {
+	fn set_flags<DN: tb::Bool, HN: tb::Bool, TN: tb::Bool, CN: tb::Bool, SN: tb::Bool, MN: tb::Bool>(self) -> InvoiceBuilder<DN, HN, TN, CN, SN, MN> {
+ InvoiceBuilder::<DN, HN, TN, CN, SN, MN> {
  currency: self.currency,
  amount: self.amount,
  si_prefix: self.si_prefix,
@@ -509,6 +516,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
  phantom_t: core::marker::PhantomData,
  phantom_c: core::marker::PhantomData,
  phantom_s: core::marker::PhantomData,
+ phantom_m: core::marker::PhantomData,
  }
 	}
 
@@ -552,7 +560,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBui
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::True, C, S, M> {
 	/// Builds a `RawInvoice` if no `CreationError` occurred while construction any of the fields.
 	pub fn build_raw(self) -> Result<RawInvoice, CreationError> {
 
@@ -585,9 +593,9 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 }
 
-impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S> {
+impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<tb::False, H, T, C, S, M> {
 	/// Set the description. This function is only available if no description (hash) was set.
-	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description(mut self, description: String) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  match Description::new(description) {
  Ok(d) => self.tagged_fields.push(TaggedField::Description(d)),
  Err(e) => self.error = Some(e),
@@ -596,24 +604,24 @@ impl<H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<tb::Fals
 	}
 
 	/// Set the description hash. This function is only available if no description (hash) was set.
-	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S> {
+	pub fn description_hash(mut self, description_hash: sha256::Hash) -> InvoiceBuilder<tb::True, H, T, C, S, M> {
  self.tagged_fields.push(TaggedField::DescriptionHash(Sha256(description_hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S> {
+impl<D: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, tb::False, T, C, S, M> {
 	/// Set the payment hash. This function is only available if no payment hash was set.
-	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S> {
+	pub fn payment_hash(mut self, hash: sha256::Hash) -> InvoiceBuilder<D, tb::True, T, C, S, M> {
  self.tagged_fields.push(TaggedField::PaymentHash(Sha256(hash)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S> {
+impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, tb::False, C, S, M> {
 	/// Sets the timestamp to a specific [`SystemTime`].
 	#[cfg(feature = "std")]
-	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn timestamp(mut self, time: SystemTime) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_system_time(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -623,7 +631,7 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 	}
 
 	/// Sets the timestamp to a duration since the Unix epoch.
-	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn duration_since_epoch(mut self, time: Duration) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  match PositiveTimestamp::from_duration_since_epoch(time) {
  Ok(t) => self.timestamp = Some(t),
  Err(e) => self.error = Some(e),
@@ -634,34 +642,96 @@ impl<D: tb::Bool, H: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, tb
 
 	/// Sets the timestamp to the current system time.
 	#[cfg(feature = "std")]
-	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S> {
+	pub fn current_timestamp(mut self) -> InvoiceBuilder<D, H, tb::True, C, S, M> {
  let now = PositiveTimestamp::from_system_time(SystemTime::now());
  self.timestamp = Some(now.expect("for the foreseeable future this shouldn't happen"));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, S: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, tb::False, S, M> {
 	/// Sets `min_final_cltv_expiry`.
-	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S> {
+	pub fn min_final_cltv_expiry(mut self, min_final_cltv_expiry: u64) -> InvoiceBuilder<D, H, T, tb::True, S, M> {
  self.tagged_fields.push(TaggedField::MinFinalCltvExpiry(MinFinalCltvExpiry(min_final_cltv_expiry)));
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::False, M> {
 	/// Sets the payment secret and relevant features.
-	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True> {
- let mut features = InvoiceFeatures::empty();
- features.set_variable_length_onion_required();
- features.set_payment_secret_required();
+	pub fn payment_secret(mut self, payment_secret: PaymentSecret) -> InvoiceBuilder<D, H, T, C, tb::True, M> {
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_variable_length_onion_required();
+ f.set_payment_secret_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
  self.tagged_fields.push(TaggedField::PaymentSecret(payment_secret));
- self.tagged_fields.push(TaggedField::Features(features));
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_variable_length_onion_required();
+ features.set_payment_secret_required();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
+ self.set_flags()
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::False> {
+	/// Sets the payment metadata.
+	///
+	/// By default features are set to *optionally* allow the sender to include the payment metadata.
+	/// If you wish to require that the sender include the metadata (and fail to parse the invoice if
+	/// they don't support payment metadata fields), you need to call
+	/// [`InvoiceBuilder::require_payment_metadata`] after this.
+	pub fn payment_metadata(mut self, payment_metadata: Vec<u8>) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields.push(TaggedField::PaymentMetadata(payment_metadata));
+ let mut found_features = false;
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ found_features = true;
+ f.set_payment_metadata_optional();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ if !found_features {
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_metadata_optional();
+ self.tagged_fields.push(TaggedField::Features(features));
+ }
  self.set_flags()
 	}
 }
 
-impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True> {
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, S: tb::Bool> InvoiceBuilder<D, H, T, C, S, tb::True> {
+	/// Sets the payment secret and relevant features.
+	pub fn require_payment_metadata(mut self) -> InvoiceBuilder<D, H, T, C, S, tb::True> {
+ self.tagged_fields = self.tagged_fields
+ .drain(..)
+ .map(|field| match field {
+ TaggedField::Features(mut f) => {
+ f.set_payment_metadata_required();
+ TaggedField::Features(f)
+ },
+ _ => field,
+ })
+ .collect();
+ self
+	}
+}
+
+impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool, M: tb::Bool> InvoiceBuilder<D, H, T, C, tb::True, M> {
 	/// Sets the `basic_mpp` feature as optional.
 	pub fn basic_mpp(mut self) -> Self {
  for field in self.tagged_fields.iter_mut() {
@@ -673,7 +743,7 @@ impl<D: tb::Bool, H: tb::Bool, T: tb::Bool, C: tb::Bool> InvoiceBuilder<D, H, T,
 	}
 }
 
-implInvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True> {
+impl<M: tb::Bool> InvoiceBuilder<tb::True, tb::True, tb::True, tb::True, tb::True, M> {
 	/// Builds and signs an invoice using the supplied `sign_function`. This function MAY NOT fail
 	/// and MUST produce a recoverable signature valid for the given hash and if applicable also for
 	/// the included payee public key.
@@ -926,6 +996,10 @@ impl RawInvoice {
  find_extract!(self.known_tagged_fields(), TaggedField::PaymentSecret(ref x), x)
 	}
 
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ find_extract!(self.known_tagged_fields(), TaggedField::PaymentMetadata(ref x), x)
+	}
+
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  find_extract!(self.known_tagged_fields(), TaggedField::Features(ref x), x)
 	}
@@ -1188,6 +1262,11 @@ impl Invoice {
  self.signed_invoice.payment_secret().expect("was checked by constructor")
 	}
 
+	/// Get the payment metadata blob if one was included in the invoice
+	pub fn payment_metadata(&self) -> Option<&Vec<u8>> {
+ self.signed_invoice.payment_metadata()
+	}
+
 	/// Get the invoice features if they were included in the invoice
 	pub fn features(&self) -> Option<&InvoiceFeatures> {
  self.signed_invoice.features()
@@ -1290,6 +1369,7 @@ impl TaggedField {
  TaggedField::Fallback(_) => constants::TAG_FALLBACK,
  TaggedField::PrivateRoute(_) => constants::TAG_PRIVATE_ROUTE,
  TaggedField::PaymentSecret(_) => constants::TAG_PAYMENT_SECRET,
+ TaggedField::PaymentMetadata(_) => constants::TAG_PAYMENT_METADATA,
  TaggedField::Features(_) => constants::TAG_FEATURES,
  };
 
@@ -1922,7 +2002,11 @@ mod test {
  );
  assert_eq!(invoice.payment_hash(), &sha256::Hash::from_slice(&[21;32][..]).unwrap());
  assert_eq!(invoice.payment_secret(), &PaymentSecret([42; 32]));
- assert_eq!(invoice.features(), Some(&InvoiceFeatures::known()));
+ let mut features = InvoiceFeatures::empty();
+ features.set_payment_secret_required();
+ features.set_variable_length_onion_required();
+ features.set_basic_mpp_optional();
+ assert_eq!(invoice.features(), Some(&features));
 
  let raw_invoice = builder.build_raw().unwrap();
  assert_eq!(raw_invoice, *invoice.into_signed_raw().raw_invoice())