Add c_bindings version of InvoiceBuilder

Use the macros introduced in the previous commit to define two builders
for each type parameterization of InvoiceBuilder
- InvoiceWithExplicitSigningPubkeyBuilder
- InvoiceWithDerivedSigningPubkeyBuilder

The difference between these and InvoiceBuilder is that these have
methods that take `self` by mutable reference instead of by value and
don't return anything instead returning the modified builder. This is
required because bindings don't support move semantics nor impl blocks
specific to a certain type parameterization. Because of this, the
builder's contents must be cloned when building a Bolt12Invoice.

Keeps InvoiceBuilder defined so that it can be used internally in
ChannelManager's OffersMessageHandler even when compiled for c_bindings.

lightning/src/ln/channelmanager.rs

@@ -57,7 +57,7 @@ use crate::ln::msgs::{ChannelMessageHandler, DecodeError, LightningError};
 use crate::ln::outbound_payment;
 use crate::ln::outbound_payment::{Bolt12PaymentError, OutboundPayments, PaymentAttempts, PendingOutboundPayment, SendAlongPathArgs, StaleExpiration};
 use crate::ln::wire::Encode;
-use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, DerivedSigningPubkey, InvoiceBuilder};
+use crate::offers::invoice::{BlindedPayInfo, Bolt12Invoice, DEFAULT_RELATIVE_EXPIRY, DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder};
 use crate::offers::invoice_error::InvoiceError;
 use crate::offers::invoice_request::{DerivedPayerId, InvoiceRequestBuilder};
 use crate::offers::merkle::SignError;
@@ -9281,6 +9281,8 @@ where
 					let builder = invoice_request.respond_using_derived_keys_no_std(
 						payment_paths, payment_hash, created_at
 					);
+					let builder: Result<InvoiceBuilder<DerivedSigningPubkey>, _> =
+						builder.map(|b| b.into());
 					match builder.and_then(|b| b.allow_mpp().build_and_sign(secp_ctx)) {
 						Ok(invoice) => Some(OffersMessage::Invoice(invoice)),
 						Err(error) => Some(OffersMessage::InvoiceError(error.into())),
@@ -9292,6 +9294,8 @@ where
 					let builder = invoice_request.respond_with_no_std(
 						payment_paths, payment_hash, created_at
 					);
+					let builder: Result<InvoiceBuilder<ExplicitSigningPubkey>, _> =
+						builder.map(|b| b.into());
 					let response = builder.and_then(|builder| builder.allow_mpp().build())
 						.map_err(|e| OffersMessage::InvoiceError(e.into()))
 						.and_then(|invoice|

lightning/src/offers/invoice.rs

@@ -151,6 +151,38 @@ pub struct InvoiceBuilder<'a, S: SigningPubkeyStrategy> {
 	signing_pubkey_strategy: S,
 }
 
+/// Builds a [`Bolt12Invoice`] from either:
+/// - an [`InvoiceRequest`] for the "offer to be paid" flow or
+/// - a [`Refund`] for the "offer for money" flow.
+///
+/// See [module-level documentation] for usage.
+///
+/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+/// [`Refund`]: crate::offers::refund::Refund
+/// [module-level documentation]: self
+#[cfg(c_bindings)]
+pub struct InvoiceWithExplicitSigningPubkeyBuilder<'a> {
+	invreq_bytes: &'a Vec<u8>,
+	invoice: InvoiceContents,
+	signing_pubkey_strategy: ExplicitSigningPubkey,
+}
+
+/// Builds a [`Bolt12Invoice`] from either:
+/// - an [`InvoiceRequest`] for the "offer to be paid" flow or
+/// - a [`Refund`] for the "offer for money" flow.
+///
+/// See [module-level documentation] for usage.
+///
+/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+/// [`Refund`]: crate::offers::refund::Refund
+/// [module-level documentation]: self
+#[cfg(c_bindings)]
+pub struct InvoiceWithDerivedSigningPubkeyBuilder<'a> {
+	invreq_bytes: &'a Vec<u8>,
+	invoice: InvoiceContents,
+	signing_pubkey_strategy: DerivedSigningPubkey,
+}
+
 /// Indicates how [`Bolt12Invoice::signing_pubkey`] was set.
 ///
 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
@@ -216,8 +248,13 @@ macro_rules! invoice_explicit_signing_pubkey_builder_methods { ($self: ident, $s
 			}
 		}
 
-		let InvoiceBuilder { invreq_bytes, invoice, .. } = $self;
-		Ok(UnsignedBolt12Invoice::new(invreq_bytes, invoice))
+		let Self { invreq_bytes, invoice, .. } = $self;
+		#[cfg(not(c_bindings))] {
+			Ok(UnsignedBolt12Invoice::new(invreq_bytes, invoice))
+		}
+		#[cfg(c_bindings)] {
+			Ok(UnsignedBolt12Invoice::new(invreq_bytes, invoice.clone()))
+		}
 	}
 } }
 
@@ -272,10 +309,13 @@ macro_rules! invoice_derived_signing_pubkey_builder_methods { (
 			}
 		}
 
-		let InvoiceBuilder {
+		let Self {
 			invreq_bytes, invoice, signing_pubkey_strategy: DerivedSigningPubkey(keys)
 		} = $self;
+		#[cfg(not(c_bindings))]
 		let unsigned_invoice = UnsignedBolt12Invoice::new(invreq_bytes, invoice);
+		#[cfg(c_bindings)]
+		let unsigned_invoice = UnsignedBolt12Invoice::new(invreq_bytes, invoice.clone());
 
 		let invoice = unsigned_invoice
 			.sign::<_, Infallible>(
@@ -287,7 +327,7 @@ macro_rules! invoice_derived_signing_pubkey_builder_methods { (
 } }
 
 macro_rules! invoice_builder_methods { (
-	$self: ident, $self_type: ty, $return_type: ty, $return_value: expr
+	$self: ident, $self_type: ty, $return_type: ty, $return_value: expr, $type_param: ty
 ) => {
 	pub(crate) fn amount_msats(
 		invoice_request: &InvoiceRequest
@@ -316,7 +356,7 @@ macro_rules! invoice_builder_methods { (
 	}
 
 	fn new(
-		invreq_bytes: &'a Vec<u8>, contents: InvoiceContents, signing_pubkey_strategy: S
+		invreq_bytes: &'a Vec<u8>, contents: InvoiceContents, signing_pubkey_strategy: $type_param
 	) -> Result<Self, Bolt12SemanticError> {
 		if contents.fields().payment_paths.is_empty() {
 			return Err(Bolt12SemanticError::MissingPaths);
@@ -392,7 +432,59 @@ impl<'a> InvoiceBuilder<'a, DerivedSigningPubkey> {
 }
 
 impl<'a, S: SigningPubkeyStrategy> InvoiceBuilder<'a, S> {
-	invoice_builder_methods!(self, Self, Self, self);
+	invoice_builder_methods!(self, Self, Self, self, S);
+}
+
+#[cfg(all(c_bindings, not(test)))]
+impl<'a> InvoiceWithExplicitSigningPubkeyBuilder<'a> {
+	invoice_explicit_signing_pubkey_builder_methods!(self, &mut Self);
+	invoice_builder_methods!(self, &mut Self, (), (), ExplicitSigningPubkey);
+}
+
+#[cfg(all(c_bindings, test))]
+impl<'a> InvoiceWithExplicitSigningPubkeyBuilder<'a> {
+	invoice_explicit_signing_pubkey_builder_methods!(self, &mut Self);
+	invoice_builder_methods!(self, &mut Self, &mut Self, self, ExplicitSigningPubkey);
+}
+
+#[cfg(all(c_bindings, not(test)))]
+impl<'a> InvoiceWithDerivedSigningPubkeyBuilder<'a> {
+	invoice_derived_signing_pubkey_builder_methods!(self, &mut Self, secp256k1::All);
+	invoice_builder_methods!(self, &mut Self, (), (), DerivedSigningPubkey);
+}
+
+#[cfg(all(c_bindings, test))]
+impl<'a> InvoiceWithDerivedSigningPubkeyBuilder<'a> {
+	invoice_derived_signing_pubkey_builder_methods!(self, &mut Self, secp256k1::All);
+	invoice_builder_methods!(self, &mut Self, &mut Self, self, DerivedSigningPubkey);
+}
+
+#[cfg(c_bindings)]
+impl<'a> From<InvoiceWithDerivedSigningPubkeyBuilder<'a>>
+for InvoiceBuilder<'a, DerivedSigningPubkey> {
+	fn from(builder: InvoiceWithDerivedSigningPubkeyBuilder<'a>) -> Self {
+		let InvoiceWithDerivedSigningPubkeyBuilder {
+			invreq_bytes, invoice, signing_pubkey_strategy,
+		} = builder;
+
+		Self {
+			invreq_bytes, invoice, signing_pubkey_strategy,
+		}
+	}
+}
+
+#[cfg(c_bindings)]
+impl<'a> From<InvoiceWithExplicitSigningPubkeyBuilder<'a>>
+for InvoiceBuilder<'a, ExplicitSigningPubkey> {
+	fn from(builder: InvoiceWithExplicitSigningPubkeyBuilder<'a>) -> Self {
+		let InvoiceWithExplicitSigningPubkeyBuilder {
+			invreq_bytes, invoice, signing_pubkey_strategy,
+		} = builder;
+
+		Self {
+			invreq_bytes, invoice, signing_pubkey_strategy,
+		}
+	}
 }
 
 /// A semantically valid [`Bolt12Invoice`] that hasn't been signed.
@@ -1685,7 +1777,7 @@ mod tests {
 		if let Err(e) = invoice_request.clone()
 			.verify(&expanded_key, &secp_ctx).unwrap()
 			.respond_using_derived_keys_no_std(payment_paths(), payment_hash(), now()).unwrap()
-			.build_and_sign(&secp_ctx)
+			.build_and_sign::<secp256k1::All>(&secp_ctx)
 		{
 			panic!("error building invoice: {:?}", e);
 		}
@@ -2122,8 +2214,13 @@ mod tests {
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 			.build().unwrap()
 			.sign(payer_sign).unwrap();
+		#[cfg(not(c_bindings))]
+		let invoice_builder = invoice_request
+			.respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap();
+		#[cfg(c_bindings)]
 		let mut invoice_builder = invoice_request
-			.respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
+			.respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap();
+		let mut invoice_builder = invoice_builder
 			.fallback_v0_p2wsh(&script.wscript_hash())
 			.fallback_v0_p2wpkh(&pubkey.wpubkey_hash().unwrap())
 			.fallback_v1_p2tr_tweaked(&tweaked_pubkey);

lightning/src/offers/invoice_request.rs

@@ -68,7 +68,7 @@ use crate::ln::channelmanager::PaymentId;
 use crate::ln::features::InvoiceRequestFeatures;
 use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
 use crate::ln::msgs::DecodeError;
-use crate::offers::invoice::{BlindedPayInfo, DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder};
+use crate::offers::invoice::BlindedPayInfo;
 use crate::offers::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
 use crate::offers::offer::{Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef};
 use crate::offers::parse::{Bolt12ParseError, ParsedMessage, Bolt12SemanticError};
@@ -77,6 +77,15 @@ use crate::offers::signer::{Metadata, MetadataMaterial};
 use crate::util::ser::{HighZeroBytesDroppedBigSize, SeekReadable, WithoutLength, Writeable, Writer};
 use crate::util::string::PrintableString;
 
+#[cfg(not(c_bindings))]
+use {
+	crate::offers::invoice::{DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder},
+};
+#[cfg(c_bindings)]
+use {
+	crate::offers::invoice::{InvoiceWithDerivedSigningPubkeyBuilder, InvoiceWithExplicitSigningPubkeyBuilder},
+};
+
 use crate::prelude::*;
 
 /// Tag for the hash function used when signing an [`InvoiceRequest`]'s merkle root.
@@ -643,8 +652,6 @@ macro_rules! invoice_request_respond_with_explicit_signing_pubkey_methods { (
 	/// See [`InvoiceRequest::respond_with_no_std`] for further details where the aforementioned
 	/// creation time is used for the `created_at` parameter.
 	///
-	/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-	///
 	/// [`Duration`]: core::time::Duration
 	#[cfg(feature = "std")]
 	pub fn respond_with(
@@ -678,8 +685,6 @@ macro_rules! invoice_request_respond_with_explicit_signing_pubkey_methods { (
 	/// If the originating [`Offer`] was created using [`OfferBuilder::deriving_signing_pubkey`],
 	/// then use [`InvoiceRequest::verify`] and [`VerifiedInvoiceRequest`] methods instead.
 	///
-	/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-	///
 	/// [`Bolt12Invoice::created_at`]: crate::offers::invoice::Bolt12Invoice::created_at
 	/// [`OfferBuilder::deriving_signing_pubkey`]: crate::offers::offer::OfferBuilder::deriving_signing_pubkey
 	pub fn respond_with_no_std(
@@ -700,24 +705,45 @@ macro_rules! invoice_request_verify_method { ($self: ident, $self_type: ty) => {
 	/// if they could be extracted from the metadata.
 	///
 	/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
-	pub fn verify<T: secp256k1::Signing>(
-		$self: $self_type, key: &ExpandedKey, secp_ctx: &Secp256k1<T>
+	pub fn verify<
+		#[cfg(not(c_bindings))]
+		T: secp256k1::Signing
+	>(
+		$self: $self_type, key: &ExpandedKey,
+		#[cfg(not(c_bindings))]
+		secp_ctx: &Secp256k1<T>,
+		#[cfg(c_bindings)]
+		secp_ctx: &Secp256k1<secp256k1::All>,
 	) -> Result<VerifiedInvoiceRequest, ()> {
 		let keys = $self.contents.inner.offer.verify(&$self.bytes, key, secp_ctx)?;
 		Ok(VerifiedInvoiceRequest {
+			#[cfg(not(c_bindings))]
 			inner: $self,
+			#[cfg(c_bindings)]
+			inner: $self.clone(),
 			keys,
 		})
 	}
 
 } }
 
+#[cfg(not(c_bindings))]
 impl InvoiceRequest {
 	offer_accessors!(self, self.contents.inner.offer);
 	invoice_request_accessors!(self, self.contents);
 	invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self, InvoiceBuilder<ExplicitSigningPubkey>);
 	invoice_request_verify_method!(self, Self);
+}
 
+#[cfg(c_bindings)]
+impl InvoiceRequest {
+	offer_accessors!(self, self.contents.inner.offer);
+	invoice_request_accessors!(self, self.contents);
+	invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self, InvoiceWithExplicitSigningPubkeyBuilder);
+	invoice_request_verify_method!(self, &Self);
+}
+
+impl InvoiceRequest {
 	/// Signature of the invoice request using [`payer_id`].
 	///
 	/// [`payer_id`]: Self::payer_id
@@ -744,8 +770,6 @@ macro_rules! invoice_request_respond_with_derived_signing_pubkey_methods { (
 	///
 	/// See [`InvoiceRequest::respond_with`] for further details.
 	///
-	/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-	///
 	/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 	#[cfg(feature = "std")]
 	pub fn respond_using_derived_keys(
@@ -764,8 +788,6 @@ macro_rules! invoice_request_respond_with_derived_signing_pubkey_methods { (
 	///
 	/// See [`InvoiceRequest::respond_with_no_std`] for further details.
 	///
-	/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-	///
 	/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 	pub fn respond_using_derived_keys_no_std(
 		&$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
@@ -789,8 +811,14 @@ macro_rules! invoice_request_respond_with_derived_signing_pubkey_methods { (
 impl VerifiedInvoiceRequest {
 	offer_accessors!(self, self.inner.contents.inner.offer);
 	invoice_request_accessors!(self, self.inner.contents);
+	#[cfg(not(c_bindings))]
 	invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self.inner, InvoiceBuilder<ExplicitSigningPubkey>);
+	#[cfg(c_bindings)]
+	invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self.inner, InvoiceWithExplicitSigningPubkeyBuilder);
+	#[cfg(not(c_bindings))]
 	invoice_request_respond_with_derived_signing_pubkey_methods!(self, self.inner, InvoiceBuilder<DerivedSigningPubkey>);
+	#[cfg(c_bindings)]
+	invoice_request_respond_with_derived_signing_pubkey_methods!(self, self.inner, InvoiceWithDerivedSigningPubkeyBuilder);
 }
 
 impl InvoiceRequestContents {