Restructure FFI bindings with conversion traits for Lightning types

This commit reorganizes the FFI architecture by introducing conversion
traits for lightning types. Moves code from uniffi_types.rs to a
dedicated ffi module for separation of concerns.

Author: alexanderwiederin

src/ffi/conversions.rs

@@ -0,0 +1,77 @@
+// This file is Copyright its original authors, visible in version control history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. You may not use this file except in
+// accordance with one or both of these licenses.
+
+mod uniffi_impl {
+	use std::sync::Arc;
+
+	use lightning_invoice::{
+		Bolt11Invoice as LdkBolt11Invoice, Bolt11InvoiceDescription as LdkBolt11InvoiceDescription,
+	};
+
+	use crate::error::Error;
+	use crate::ffi::{Bolt11Invoice, Bolt11InvoiceDescription};
+
+	pub trait UniffiType {
+		type LdkType;
+
+		fn from_ldk(ldk_value: Self::LdkType) -> Self;
+	}
+
+	pub trait UniffiConversionType: UniffiType {
+		fn as_ldk(&self) -> Self::LdkType;
+	}
+
+	pub trait UniffiFallibleConversionType: UniffiType {
+		fn try_as_ldk(&self) -> Result<Self::LdkType, Error>;
+	}
+
+	impl UniffiType for Bolt11InvoiceDescription {
+		type LdkType = LdkBolt11InvoiceDescription;
+
+		fn from_ldk(ldk_value: Self::LdkType) -> Self {
+			Bolt11InvoiceDescription::from(ldk_value)
+		}
+	}
+
+	impl UniffiFallibleConversionType for Bolt11InvoiceDescription {
+		fn try_as_ldk(&self) -> Result<Self::LdkType, Error> {
+			LdkBolt11InvoiceDescription::try_from(self)
+		}
+	}
+
+	impl UniffiType for Arc<Bolt11Invoice> {
+		type LdkType = LdkBolt11Invoice;
+
+		fn from_ldk(ldk_value: Self::LdkType) -> Self {
+			Arc::new(Bolt11Invoice { inner: ldk_value })
+		}
+	}
+
+	impl UniffiConversionType for Arc<Bolt11Invoice> {
+		fn as_ldk(&self) -> Self::LdkType {
+			self.inner.clone()
+		}
+	}
+
+	pub fn maybe_convert<T: UniffiConversionType>(value: &T) -> T::LdkType {
+		value.as_ldk()
+	}
+
+	pub fn maybe_try_convert<T: UniffiFallibleConversionType>(
+		value: &T,
+	) -> Result<T::LdkType, Error> {
+		value.try_as_ldk()
+	}
+
+	pub fn maybe_wrap<T: UniffiType>(ldk_value: T::LdkType) -> T {
+		T::from_ldk(ldk_value)
+	}
+}
+
+pub use uniffi_impl::maybe_convert;
+pub use uniffi_impl::maybe_try_convert;
+pub use uniffi_impl::maybe_wrap;

src/ffi/mod.rs

@@ -0,0 +1,36 @@
+// This file is Copyright its original authors, visible in version control history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. You may not use this file except in
+
+#[cfg(feature = "uniffi")]
+pub mod types;
+
+#[cfg(feature = "uniffi")]
+mod conversions;
+
+#[cfg(feature = "uniffi")]
+pub use types::*;
+
+#[cfg(feature = "uniffi")]
+pub use conversions::maybe_convert;
+#[cfg(feature = "uniffi")]
+pub use conversions::maybe_try_convert;
+#[cfg(feature = "uniffi")]
+pub use conversions::maybe_wrap;
+
+#[cfg(not(feature = "uniffi"))]
+pub fn maybe_convert<T>(value: &T) -> &T {
+	value
+}
+
+#[cfg(not(feature = "uniffi"))]
+pub fn maybe_try_convert<T>(value: &T) -> Result<&T, crate::error::Error> {
+	Ok(value)
+}
+
+#[cfg(not(feature = "uniffi"))]
+pub fn maybe_wrap<T>(value: T) -> T {
+	value
+}

src/uniffi_types.rs renamed to src/ffi/types.rs

@@ -84,6 +84,7 @@ mod data_store;
 mod error;
 mod event;
 mod fee_estimator;
+mod ffi;
 mod gossip;
 pub mod graph;
 mod hex_utils;
@@ -96,8 +97,6 @@ mod peer_store;
 mod sweep;
 mod tx_broadcaster;
 mod types;
-#[cfg(feature = "uniffi")]
-mod uniffi_types;
 mod wallet;
 
 pub use bip39;
@@ -117,7 +116,7 @@ pub use event::Event;
 pub use io::utils::generate_entropy_mnemonic;
 
 #[cfg(feature = "uniffi")]
-use uniffi_types::*;
+use ffi::*;
 
 #[cfg(feature = "uniffi")]
 pub use builder::ArcedNodeBuilder as Builder;

src/lib.rs

@@ -1308,7 +1308,7 @@ type PaymentInfo = lightning_liquidity::lsps1::msgs::PaymentInfo;
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct PaymentInfo {
 	/// A Lightning payment using BOLT 11.
-	pub bolt11: Option<crate::uniffi_types::Bolt11PaymentInfo>,
+	pub bolt11: Option<crate::ffi::Bolt11PaymentInfo>,
 	/// An onchain payment.
 	pub onchain: Option<OnchainPaymentInfo>,
 }

src/liquidity.rs

@@ -13,6 +13,7 @@ use crate::config::{Config, LDK_PAYMENT_RETRY_TIMEOUT};
 use crate::connection::ConnectionManager;
 use crate::data_store::DataStoreUpdateResult;
 use crate::error::Error;
+use crate::ffi::{maybe_convert, maybe_try_convert, maybe_wrap};
 use crate::liquidity::LiquiditySource;
 use crate::logger::{log_error, log_info, LdkLogger, Logger};
 use crate::payment::store::{
@@ -42,43 +43,12 @@ use std::sync::{Arc, RwLock};
 #[cfg(not(feature = "uniffi"))]
 type Bolt11Invoice = LdkBolt11Invoice;
 #[cfg(feature = "uniffi")]
-type Bolt11Invoice = Arc<crate::uniffi_types::Bolt11Invoice>;
-
-#[cfg(not(feature = "uniffi"))]
-pub(crate) fn maybe_wrap_invoice(invoice: LdkBolt11Invoice) -> Bolt11Invoice {
-	invoice
-}
-#[cfg(feature = "uniffi")]
-pub(crate) fn maybe_wrap_invoice(invoice: LdkBolt11Invoice) -> Bolt11Invoice {
-	Arc::new(invoice.into())
-}
-
-#[cfg(not(feature = "uniffi"))]
-pub fn maybe_convert_invoice(invoice: &Bolt11Invoice) -> &LdkBolt11Invoice {
-	invoice
-}
-#[cfg(feature = "uniffi")]
-pub fn maybe_convert_invoice(invoice: &Bolt11Invoice) -> &LdkBolt11Invoice {
-	&invoice.inner
-}
+type Bolt11Invoice = Arc<crate::ffi::Bolt11Invoice>;
 
 #[cfg(not(feature = "uniffi"))]
 type Bolt11InvoiceDescription = LdkBolt11InvoiceDescription;
 #[cfg(feature = "uniffi")]
-type Bolt11InvoiceDescription = crate::uniffi_types::Bolt11InvoiceDescription;
-
-macro_rules! maybe_convert_description {
-	($description: expr) => {{
-		#[cfg(not(feature = "uniffi"))]
-		{
-			$description
-		}
-		#[cfg(feature = "uniffi")]
-		{
-			&LdkBolt11InvoiceDescription::try_from($description)?
-		}
-	}};
-}
+type Bolt11InvoiceDescription = crate::ffi::Bolt11InvoiceDescription;
 
 /// A payment handler allowing to create and pay [BOLT 11] invoices.
 ///
@@ -125,7 +95,7 @@ impl Bolt11Payment {
 	pub fn send(
 		&self, invoice: &Bolt11Invoice, sending_parameters: Option<SendingParameters>,
 	) -> Result<PaymentId, Error> {
-		let invoice = maybe_convert_invoice(invoice);
+		let invoice = maybe_convert(invoice);
 		let rt_lock = self.runtime.read().unwrap();
 		if rt_lock.is_none() {
 			return Err(Error::NotRunning);
@@ -234,7 +204,7 @@ impl Bolt11Payment {
 		&self, invoice: &Bolt11Invoice, amount_msat: u64,
 		sending_parameters: Option<SendingParameters>,
 	) -> Result<PaymentId, Error> {
-		let invoice = maybe_convert_invoice(invoice);
+		let invoice = maybe_convert(invoice);
 		let rt_lock = self.runtime.read().unwrap();
 		if rt_lock.is_none() {
 			return Err(Error::NotRunning);
@@ -466,9 +436,9 @@ impl Bolt11Payment {
 	pub fn receive(
 		&self, amount_msat: u64, description: &Bolt11InvoiceDescription, expiry_secs: u32,
 	) -> Result<Bolt11Invoice, Error> {
-		let description = maybe_convert_description!(description);
-		let invoice = self.receive_inner(Some(amount_msat), description, expiry_secs, None)?;
-		Ok(maybe_wrap_invoice(invoice))
+		let description = maybe_try_convert(description)?;
+		let invoice = self.receive_inner(Some(amount_msat), &description, expiry_secs, None)?;
+		Ok(maybe_wrap(invoice))
 	}
 
 	/// Returns a payable invoice that can be used to request a payment of the amount
@@ -489,10 +459,10 @@ impl Bolt11Payment {
 		&self, amount_msat: u64, description: &Bolt11InvoiceDescription, expiry_secs: u32,
 		payment_hash: PaymentHash,
 	) -> Result<Bolt11Invoice, Error> {
-		let description = maybe_convert_description!(description);
+		let description = maybe_try_convert(description)?;
 		let invoice =
-			self.receive_inner(Some(amount_msat), description, expiry_secs, Some(payment_hash))?;
-		Ok(maybe_wrap_invoice(invoice))
+			self.receive_inner(Some(amount_msat), &description, expiry_secs, Some(payment_hash))?;
+		Ok(maybe_wrap(invoice))
 	}
 
 	/// Returns a payable invoice that can be used to request and receive a payment for which the
@@ -502,9 +472,9 @@ impl Bolt11Payment {
 	pub fn receive_variable_amount(
 		&self, description: &Bolt11InvoiceDescription, expiry_secs: u32,
 	) -> Result<Bolt11Invoice, Error> {
-		let description = maybe_convert_description!(description);
-		let invoice = self.receive_inner(None, description, expiry_secs, None)?;
-		Ok(maybe_wrap_invoice(invoice))
+		let description = maybe_try_convert(description)?;
+		let invoice = self.receive_inner(None, &description, expiry_secs, None)?;
+		Ok(maybe_wrap(invoice))
 	}
 
 	/// Returns a payable invoice that can be used to request a payment for the given payment hash
@@ -524,9 +494,9 @@ impl Bolt11Payment {
 	pub fn receive_variable_amount_for_hash(
 		&self, description: &Bolt11InvoiceDescription, expiry_secs: u32, payment_hash: PaymentHash,
 	) -> Result<Bolt11Invoice, Error> {
-		let description = maybe_convert_description!(description);
-		let invoice = self.receive_inner(None, description, expiry_secs, Some(payment_hash))?;
-		Ok(maybe_wrap_invoice(invoice))
+		let description = maybe_try_convert(description)?;
+		let invoice = self.receive_inner(None, &description, expiry_secs, Some(payment_hash))?;
+		Ok(maybe_wrap(invoice))
 	}
 
 	pub(crate) fn receive_inner(
@@ -601,15 +571,15 @@ impl Bolt11Payment {
 		&self, amount_msat: u64, description: &Bolt11InvoiceDescription, expiry_secs: u32,
 		max_total_lsp_fee_limit_msat: Option<u64>,
 	) -> Result<Bolt11Invoice, Error> {
-		let description = maybe_convert_description!(description);
+		let description = maybe_try_convert(description)?;
 		let invoice = self.receive_via_jit_channel_inner(
 			Some(amount_msat),
-			description,
+			&description,
 			expiry_secs,
 			max_total_lsp_fee_limit_msat,
 			None,
 		)?;
-		Ok(maybe_wrap_invoice(invoice))
+		Ok(maybe_wrap(invoice))
 	}
 
 	/// Returns a payable invoice that can be used to request a variable amount payment (also known
@@ -627,15 +597,15 @@ impl Bolt11Payment {
 		&self, description: &Bolt11InvoiceDescription, expiry_secs: u32,
 		max_proportional_lsp_fee_limit_ppm_msat: Option<u64>,
 	) -> Result<Bolt11Invoice, Error> {
-		let description = maybe_convert_description!(description);
+		let description = maybe_try_convert(description)?;
 		let invoice = self.receive_via_jit_channel_inner(
 			None,
-			description,
+			&description,
 			expiry_secs,
 			None,
 			max_proportional_lsp_fee_limit_ppm_msat,
 		)?;
-		Ok(maybe_wrap_invoice(invoice))
+		Ok(maybe_wrap(invoice))
 	}
 
 	fn receive_via_jit_channel_inner(
@@ -742,7 +712,7 @@ impl Bolt11Payment {
 	/// amount times [`Config::probing_liquidity_limit_multiplier`] won't be used to send
 	/// pre-flight probes.
 	pub fn send_probes(&self, invoice: &Bolt11Invoice) -> Result<(), Error> {
-		let invoice = maybe_convert_invoice(invoice);
+		let invoice = maybe_convert(invoice);
 		let rt_lock = self.runtime.read().unwrap();
 		if rt_lock.is_none() {
 			return Err(Error::NotRunning);
@@ -775,7 +745,7 @@ impl Bolt11Payment {
 	pub fn send_probes_using_amount(
 		&self, invoice: &Bolt11Invoice, amount_msat: u64,
 	) -> Result<(), Error> {
-		let invoice = maybe_convert_invoice(invoice);
+		let invoice = maybe_convert(invoice);
 		let rt_lock = self.runtime.read().unwrap();
 		if rt_lock.is_none() {
 			return Err(Error::NotRunning);

src/payment/bolt11.rs

@@ -12,8 +12,9 @@
 //! [BOLT 11]: https://github.com/lightning/bolts/blob/master/11-payment-encoding.md
 //! [BOLT 12]: https://github.com/lightning/bolts/blob/master/12-offer-encoding.md
 use crate::error::Error;
+use crate::ffi::maybe_wrap;
 use crate::logger::{log_error, LdkLogger, Logger};
-use crate::payment::{bolt11::maybe_wrap_invoice, Bolt11Payment, Bolt12Payment, OnchainPayment};
+use crate::payment::{Bolt11Payment, Bolt12Payment, OnchainPayment};
 use crate::Config;
 
 use lightning::ln::channelmanager::PaymentId;
@@ -153,7 +154,7 @@ impl UnifiedQrPayment {
 		}
 
 		if let Some(invoice) = uri_network_checked.extras.bolt11_invoice {
-			let invoice = maybe_wrap_invoice(invoice);
+			let invoice = maybe_wrap(invoice);
 			match self.bolt11_invoice.send(&invoice, None) {
 				Ok(payment_id) => return Ok(QrPaymentResult::Bolt11 { payment_id }),
 				Err(e) => log_error!(self.logger, "Failed to send BOLT11 invoice: {:?}. This is part of a unified QR code payment. Falling back to the on-chain transaction.", e),