X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Foffers%2Finvoice_request.rs;h=aa6d7c067d0c8f54a2ce06b474038d5dd038a3ad;hb=e61001f60daa4f3d96c3b3f54cd3a8b00051ebe0;hp=bd6d58371a9f316cccf6b362cc4825f27171f177;hpb=ffe9ae285d0c0399a11b6ee4ddb81c1588ab06f2;p=rust-lightning

diff --git a/lightning/src/offers/invoice_request.rs b/lightning/src/offers/invoice_request.rs
index bd6d5837..aa6d7c06 100644
--- a/lightning/src/offers/invoice_request.rs
+++ b/lightning/src/offers/invoice_request.rs
@@ -25,8 +25,8 @@
 //!
 //! use bitcoin::network::constants::Network;
 //! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
-//! use core::convert::Infallible;
 //! use lightning::ln::features::OfferFeatures;
+//! use lightning::offers::invoice_request::UnsignedInvoiceRequest;
 //! use lightning::offers::offer::Offer;
 //! use lightning::util::ser::Writeable;
 //!
@@ -36,16 +36,19 @@
 //! let pubkey = PublicKey::from(keys);
 //! let mut buffer = Vec::new();
 //!
+//! # use lightning::offers::invoice_request::{ExplicitPayerId, InvoiceRequestBuilder};
+//! # <InvoiceRequestBuilder<ExplicitPayerId, _>>::from(
 //! "lno1qcp4256ypq"
 //!     .parse::<Offer>()?
 //!     .request_invoice(vec![42; 64], pubkey)?
+//! # )
 //!     .chain(Network::Testnet)?
 //!     .amount_msats(1000)?
 //!     .quantity(5)?
 //!     .payer_note("foo".to_string())
 //!     .build()?
-//!     .sign::<_, Infallible>(
-//!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+//!     .sign(|message: &UnsignedInvoiceRequest|
+//!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
 //!     )
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
@@ -58,7 +61,6 @@ use bitcoin::blockdata::constants::ChainHash;
 use bitcoin::network::constants::Network;
 use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, self};
 use bitcoin::secp256k1::schnorr::Signature;
-use core::convert::{AsRef, Infallible, TryFrom};
 use core::ops::Deref;
 use crate::sign::EntropySource;
 use crate::io;
@@ -68,15 +70,25 @@ 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::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
-use crate::offers::offer::{Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef};
+use crate::offers::invoice::BlindedPayInfo;
+use crate::offers::merkle::{SignError, SignFn, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
+use crate::offers::offer::{Offer, OfferContents, OfferId, OfferTlvStream, OfferTlvStreamRef};
 use crate::offers::parse::{Bolt12ParseError, ParsedMessage, Bolt12SemanticError};
 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};
 use crate::offers::signer::{Metadata, MetadataMaterial};
-use crate::util::ser::{HighZeroBytesDroppedBigSize, SeekReadable, WithoutLength, Writeable, Writer};
-use crate::util::string::PrintableString;
-
+use crate::util::ser::{HighZeroBytesDroppedBigSize, Readable, SeekReadable, WithoutLength, Writeable, Writer};
+use crate::util::string::{PrintableString, UntrustedString};
+
+#[cfg(not(c_bindings))]
+use {
+	crate::offers::invoice::{DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder},
+};
+#[cfg(c_bindings)]
+use {
+	crate::offers::invoice::{InvoiceWithDerivedSigningPubkeyBuilder, InvoiceWithExplicitSigningPubkeyBuilder},
+};
+
+#[allow(unused_imports)]
 use crate::prelude::*;
 
 /// Tag for the hash function used when signing an [`InvoiceRequest`]'s merkle root.
@@ -99,6 +111,34 @@ pub struct InvoiceRequestBuilder<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signi
 	secp_ctx: Option<&'b Secp256k1<T>>,
 }
 
+/// Builds an [`InvoiceRequest`] from an [`Offer`] for the "offer to be paid" flow.
+///
+/// See [module-level documentation] for usage.
+///
+/// [module-level documentation]: self
+#[cfg(c_bindings)]
+pub struct InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b> {
+	offer: &'a Offer,
+	invoice_request: InvoiceRequestContentsWithoutPayerId,
+	payer_id: Option<PublicKey>,
+	payer_id_strategy: core::marker::PhantomData<ExplicitPayerId>,
+	secp_ctx: Option<&'b Secp256k1<secp256k1::All>>,
+}
+
+/// Builds an [`InvoiceRequest`] from an [`Offer`] for the "offer to be paid" flow.
+///
+/// See [module-level documentation] for usage.
+///
+/// [module-level documentation]: self
+#[cfg(c_bindings)]
+pub struct InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b> {
+	offer: &'a Offer,
+	invoice_request: InvoiceRequestContentsWithoutPayerId,
+	payer_id: Option<PublicKey>,
+	payer_id_strategy: core::marker::PhantomData<DerivedPayerId>,
+	secp_ctx: Option<&'b Secp256k1<secp256k1::All>>,
+}
+
 /// Indicates how [`InvoiceRequest::payer_id`] will be set.
 ///
 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
@@ -117,7 +157,8 @@ pub struct DerivedPayerId {}
 impl PayerIdStrategy for ExplicitPayerId {}
 impl PayerIdStrategy for DerivedPayerId {}
 
-impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, T> {
+macro_rules! invoice_request_explicit_payer_id_builder_methods { ($self: ident, $self_type: ty) => {
+	#[cfg_attr(c_bindings, allow(dead_code))]
 	pub(super) fn new(offer: &'a Offer, metadata: Vec<u8>, payer_id: PublicKey) -> Self {
 		Self {
 			offer,
@@ -128,6 +169,7 @@ impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerI
 		}
 	}
 
+	#[cfg_attr(c_bindings, allow(dead_code))]
 	pub(super) fn deriving_metadata<ES: Deref>(
 		offer: &'a Offer, payer_id: PublicKey, expanded_key: &ExpandedKey, entropy_source: ES,
 		payment_id: PaymentId,
@@ -144,12 +186,23 @@ impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerI
 			secp_ctx: None,
 		}
 	}
-}
 
-impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId, T> {
+	/// Builds an unsigned [`InvoiceRequest`] after checking for valid semantics. It can be signed
+	/// by [`UnsignedInvoiceRequest::sign`].
+	pub fn build($self: $self_type) -> Result<UnsignedInvoiceRequest, Bolt12SemanticError> {
+		let (unsigned_invoice_request, keys, _) = $self.build_with_checks()?;
+		debug_assert!(keys.is_none());
+		Ok(unsigned_invoice_request)
+	}
+} }
+
+macro_rules! invoice_request_derived_payer_id_builder_methods { (
+	$self: ident, $self_type: ty, $secp_context: ty
+) => {
+	#[cfg_attr(c_bindings, allow(dead_code))]
 	pub(super) fn deriving_payer_id<ES: Deref>(
 		offer: &'a Offer, expanded_key: &ExpandedKey, entropy_source: ES,
-		secp_ctx: &'b Secp256k1<T>, payment_id: PaymentId
+		secp_ctx: &'b Secp256k1<$secp_context>, payment_id: PaymentId
 	) -> Self where ES::Target: EntropySource {
 		let nonce = Nonce::from_entropy_source(entropy_source);
 		let payment_id = Some(payment_id);
@@ -163,9 +216,29 @@ impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId
 			secp_ctx: Some(secp_ctx),
 		}
 	}
-}
 
-impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, P, T> {
+	/// Builds a signed [`InvoiceRequest`] after checking for valid semantics.
+	pub fn build_and_sign($self: $self_type) -> Result<InvoiceRequest, Bolt12SemanticError> {
+		let (unsigned_invoice_request, keys, secp_ctx) = $self.build_with_checks()?;
+		#[cfg(c_bindings)]
+		let mut unsigned_invoice_request = unsigned_invoice_request;
+		debug_assert!(keys.is_some());
+
+		let secp_ctx = secp_ctx.unwrap();
+		let keys = keys.unwrap();
+		let invoice_request = unsigned_invoice_request
+			.sign(|message: &UnsignedInvoiceRequest|
+				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+			)
+			.unwrap();
+		Ok(invoice_request)
+	}
+} }
+
+macro_rules! invoice_request_builder_methods { (
+	$self: ident, $self_type: ty, $return_type: ty, $return_value: expr, $secp_context: ty $(, $self_mut: tt)?
+) => {
+	#[cfg_attr(c_bindings, allow(dead_code))]
 	fn create_contents(offer: &Offer, metadata: Metadata) -> InvoiceRequestContentsWithoutPayerId {
 		let offer = offer.contents.clone();
 		InvoiceRequestContentsWithoutPayerId {
@@ -179,8 +252,8 @@ impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a
 	/// by the offer.
 	///
 	/// Successive calls to this method will override the previous setting.
-	pub fn chain(self, network: Network) -> Result<Self, Bolt12SemanticError> {
-		self.chain_hash(ChainHash::using_genesis_block(network))
+	pub fn chain($self: $self_type, network: Network) -> Result<$return_type, Bolt12SemanticError> {
+		$self.chain_hash(ChainHash::using_genesis_block(network))
 	}
 
 	/// Sets the [`InvoiceRequest::chain`] for paying an invoice. If not called, the chain hash of
@@ -188,13 +261,13 @@ impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a
 	/// offer.
 	///
 	/// Successive calls to this method will override the previous setting.
-	pub(crate) fn chain_hash(mut self, chain: ChainHash) -> Result<Self, Bolt12SemanticError> {
-		if !self.offer.supports_chain(chain) {
+	pub(crate) fn chain_hash($($self_mut)* $self: $self_type, chain: ChainHash) -> Result<$return_type, Bolt12SemanticError> {
+		if !$self.offer.supports_chain(chain) {
 			return Err(Bolt12SemanticError::UnsupportedChain);
 		}
 
-		self.invoice_request.chain = Some(chain);
-		Ok(self)
+		$self.invoice_request.chain = Some(chain);
+		Ok($return_value)
 	}
 
 	/// Sets the [`InvoiceRequest::amount_msats`] for paying an invoice. Errors if `amount_msats` is
@@ -203,156 +276,208 @@ impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a
 	/// Successive calls to this method will override the previous setting.
 	///
 	/// [`quantity`]: Self::quantity
-	pub fn amount_msats(mut self, amount_msats: u64) -> Result<Self, Bolt12SemanticError> {
-		self.invoice_request.offer.check_amount_msats_for_quantity(
-			Some(amount_msats), self.invoice_request.quantity
+	pub fn amount_msats($($self_mut)* $self: $self_type, amount_msats: u64) -> Result<$return_type, Bolt12SemanticError> {
+		$self.invoice_request.offer.check_amount_msats_for_quantity(
+			Some(amount_msats), $self.invoice_request.quantity
 		)?;
-		self.invoice_request.amount_msats = Some(amount_msats);
-		Ok(self)
+		$self.invoice_request.amount_msats = Some(amount_msats);
+		Ok($return_value)
 	}
 
 	/// Sets [`InvoiceRequest::quantity`] of items. If not set, `1` is assumed. Errors if `quantity`
 	/// does not conform to [`Offer::is_valid_quantity`].
 	///
 	/// Successive calls to this method will override the previous setting.
-	pub fn quantity(mut self, quantity: u64) -> Result<Self, Bolt12SemanticError> {
-		self.invoice_request.offer.check_quantity(Some(quantity))?;
-		self.invoice_request.quantity = Some(quantity);
-		Ok(self)
+	pub fn quantity($($self_mut)* $self: $self_type, quantity: u64) -> Result<$return_type, Bolt12SemanticError> {
+		$self.invoice_request.offer.check_quantity(Some(quantity))?;
+		$self.invoice_request.quantity = Some(quantity);
+		Ok($return_value)
 	}
 
 	/// Sets the [`InvoiceRequest::payer_note`].
 	///
 	/// Successive calls to this method will override the previous setting.
-	pub fn payer_note(mut self, payer_note: String) -> Self {
-		self.invoice_request.payer_note = Some(payer_note);
-		self
+	pub fn payer_note($($self_mut)* $self: $self_type, payer_note: String) -> $return_type {
+		$self.invoice_request.payer_note = Some(payer_note);
+		$return_value
 	}
 
-	fn build_with_checks(mut self) -> Result<
-		(UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<T>>),
+	fn build_with_checks($($self_mut)* $self: $self_type) -> Result<
+		(UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<$secp_context>>),
 		Bolt12SemanticError
 	> {
 		#[cfg(feature = "std")] {
-			if self.offer.is_expired() {
+			if $self.offer.is_expired() {
 				return Err(Bolt12SemanticError::AlreadyExpired);
 			}
 		}
 
-		let chain = self.invoice_request.chain();
-		if !self.offer.supports_chain(chain) {
+		let chain = $self.invoice_request.chain();
+		if !$self.offer.supports_chain(chain) {
 			return Err(Bolt12SemanticError::UnsupportedChain);
 		}
 
-		if chain == self.offer.implied_chain() {
-			self.invoice_request.chain = None;
+		if chain == $self.offer.implied_chain() {
+			$self.invoice_request.chain = None;
 		}
 
-		if self.offer.amount().is_none() && self.invoice_request.amount_msats.is_none() {
+		if $self.offer.amount().is_none() && $self.invoice_request.amount_msats.is_none() {
 			return Err(Bolt12SemanticError::MissingAmount);
 		}
 
-		self.invoice_request.offer.check_quantity(self.invoice_request.quantity)?;
-		self.invoice_request.offer.check_amount_msats_for_quantity(
-			self.invoice_request.amount_msats, self.invoice_request.quantity
+		$self.invoice_request.offer.check_quantity($self.invoice_request.quantity)?;
+		$self.invoice_request.offer.check_amount_msats_for_quantity(
+			$self.invoice_request.amount_msats, $self.invoice_request.quantity
 		)?;
 
-		Ok(self.build_without_checks())
+		Ok($self.build_without_checks())
 	}
 
-	fn build_without_checks(mut self) ->
-		(UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<T>>)
+	fn build_without_checks($($self_mut)* $self: $self_type) ->
+		(UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<$secp_context>>)
 	{
 		// Create the metadata for stateless verification of a Bolt12Invoice.
 		let mut keys = None;
-		let secp_ctx = self.secp_ctx.clone();
-		if self.invoice_request.payer.0.has_derivation_material() {
-			let mut metadata = core::mem::take(&mut self.invoice_request.payer.0);
+		let secp_ctx = $self.secp_ctx.clone();
+		if $self.invoice_request.payer.0.has_derivation_material() {
+			let mut metadata = core::mem::take(&mut $self.invoice_request.payer.0);
 
-			let mut tlv_stream = self.invoice_request.as_tlv_stream();
+			let mut tlv_stream = $self.invoice_request.as_tlv_stream();
 			debug_assert!(tlv_stream.2.payer_id.is_none());
 			tlv_stream.0.metadata = None;
 			if !metadata.derives_payer_keys() {
-				tlv_stream.2.payer_id = self.payer_id.as_ref();
+				tlv_stream.2.payer_id = $self.payer_id.as_ref();
 			}
 
-			let (derived_metadata, derived_keys) = metadata.derive_from(tlv_stream, self.secp_ctx);
+			let (derived_metadata, derived_keys) = metadata.derive_from(tlv_stream, $self.secp_ctx);
 			metadata = derived_metadata;
 			keys = derived_keys;
 			if let Some(keys) = keys {
-				debug_assert!(self.payer_id.is_none());
-				self.payer_id = Some(keys.public_key());
+				debug_assert!($self.payer_id.is_none());
+				$self.payer_id = Some(keys.public_key());
 			}
 
-			self.invoice_request.payer.0 = metadata;
+			$self.invoice_request.payer.0 = metadata;
 		}
 
-		debug_assert!(self.invoice_request.payer.0.as_bytes().is_some());
-		debug_assert!(self.payer_id.is_some());
-		let payer_id = self.payer_id.unwrap();
+		debug_assert!($self.invoice_request.payer.0.as_bytes().is_some());
+		debug_assert!($self.payer_id.is_some());
+		let payer_id = $self.payer_id.unwrap();
 
 		let invoice_request = InvoiceRequestContents {
-			inner: self.invoice_request,
+			#[cfg(not(c_bindings))]
+			inner: $self.invoice_request,
+			#[cfg(c_bindings)]
+			inner: $self.invoice_request.clone(),
 			payer_id,
 		};
-		let unsigned_invoice_request = UnsignedInvoiceRequest::new(self.offer, invoice_request);
+		let unsigned_invoice_request = UnsignedInvoiceRequest::new($self.offer, invoice_request);
 
 		(unsigned_invoice_request, keys, secp_ctx)
 	}
-}
+} }
 
-impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, T> {
-	/// Builds an unsigned [`InvoiceRequest`] after checking for valid semantics. It can be signed
-	/// by [`UnsignedInvoiceRequest::sign`].
-	pub fn build(self) -> Result<UnsignedInvoiceRequest, Bolt12SemanticError> {
-		let (unsigned_invoice_request, keys, _) = self.build_with_checks()?;
-		debug_assert!(keys.is_none());
-		Ok(unsigned_invoice_request)
+#[cfg(test)]
+macro_rules! invoice_request_builder_test_methods { (
+	$self: ident, $self_type: ty, $return_type: ty, $return_value: expr $(, $self_mut: tt)?
+) => {
+	#[cfg_attr(c_bindings, allow(dead_code))]
+	fn chain_unchecked($($self_mut)* $self: $self_type, network: Network) -> $return_type {
+		let chain = ChainHash::using_genesis_block(network);
+		$self.invoice_request.chain = Some(chain);
+		$return_value
 	}
-}
 
-impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId, T> {
-	/// Builds a signed [`InvoiceRequest`] after checking for valid semantics.
-	pub fn build_and_sign(self) -> Result<InvoiceRequest, Bolt12SemanticError> {
-		let (unsigned_invoice_request, keys, secp_ctx) = self.build_with_checks()?;
-		debug_assert!(keys.is_some());
-
-		let secp_ctx = secp_ctx.unwrap();
-		let keys = keys.unwrap();
-		let invoice_request = unsigned_invoice_request
-			.sign::<_, Infallible>(
-				|message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-			)
-			.unwrap();
-		Ok(invoice_request)
+	#[cfg_attr(c_bindings, allow(dead_code))]
+	fn amount_msats_unchecked($($self_mut)* $self: $self_type, amount_msats: u64) -> $return_type {
+		$self.invoice_request.amount_msats = Some(amount_msats);
+		$return_value
 	}
-}
 
-#[cfg(test)]
-impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, P, T> {
-	fn chain_unchecked(mut self, network: Network) -> Self {
-		let chain = ChainHash::using_genesis_block(network);
-		self.invoice_request.chain = Some(chain);
-		self
+	#[cfg_attr(c_bindings, allow(dead_code))]
+	fn features_unchecked($($self_mut)* $self: $self_type, features: InvoiceRequestFeatures) -> $return_type {
+		$self.invoice_request.features = features;
+		$return_value
 	}
 
-	fn amount_msats_unchecked(mut self, amount_msats: u64) -> Self {
-		self.invoice_request.amount_msats = Some(amount_msats);
-		self
+	#[cfg_attr(c_bindings, allow(dead_code))]
+	fn quantity_unchecked($($self_mut)* $self: $self_type, quantity: u64) -> $return_type {
+		$self.invoice_request.quantity = Some(quantity);
+		$return_value
 	}
 
-	fn features_unchecked(mut self, features: InvoiceRequestFeatures) -> Self {
-		self.invoice_request.features = features;
-		self
+	#[cfg_attr(c_bindings, allow(dead_code))]
+	pub(super) fn build_unchecked($self: $self_type) -> UnsignedInvoiceRequest {
+		$self.build_without_checks().0
 	}
+} }
+
+impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, T> {
+	invoice_request_explicit_payer_id_builder_methods!(self, Self);
+}
+
+impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId, T> {
+	invoice_request_derived_payer_id_builder_methods!(self, Self, T);
+}
+
+impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, P, T> {
+	invoice_request_builder_methods!(self, Self, Self, self, T, mut);
+
+	#[cfg(test)]
+	invoice_request_builder_test_methods!(self, Self, Self, self, mut);
+}
+
+#[cfg(all(c_bindings, not(test)))]
+impl<'a, 'b> InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b> {
+	invoice_request_explicit_payer_id_builder_methods!(self, &mut Self);
+	invoice_request_builder_methods!(self, &mut Self, (), (), secp256k1::All);
+}
+
+#[cfg(all(c_bindings, test))]
+impl<'a, 'b> InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b> {
+	invoice_request_explicit_payer_id_builder_methods!(self, &mut Self);
+	invoice_request_builder_methods!(self, &mut Self, &mut Self, self, secp256k1::All);
+	invoice_request_builder_test_methods!(self, &mut Self, &mut Self, self);
+}
+
+#[cfg(all(c_bindings, not(test)))]
+impl<'a, 'b> InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b> {
+	invoice_request_derived_payer_id_builder_methods!(self, &mut Self, secp256k1::All);
+	invoice_request_builder_methods!(self, &mut Self, (), (), secp256k1::All);
+}
+
+#[cfg(all(c_bindings, test))]
+impl<'a, 'b> InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b> {
+	invoice_request_derived_payer_id_builder_methods!(self, &mut Self, secp256k1::All);
+	invoice_request_builder_methods!(self, &mut Self, &mut Self, self, secp256k1::All);
+	invoice_request_builder_test_methods!(self, &mut Self, &mut Self, self);
+}
+
+#[cfg(c_bindings)]
+impl<'a, 'b> From<InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b>>
+for InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, secp256k1::All> {
+	fn from(builder: InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b>) -> Self {
+		let InvoiceRequestWithExplicitPayerIdBuilder {
+			offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+		} = builder;
 
-	fn quantity_unchecked(mut self, quantity: u64) -> Self {
-		self.invoice_request.quantity = Some(quantity);
-		self
+		Self {
+			offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+		}
 	}
+}
+
+#[cfg(c_bindings)]
+impl<'a, 'b> From<InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b>>
+for InvoiceRequestBuilder<'a, 'b, DerivedPayerId, secp256k1::All> {
+	fn from(builder: InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b>) -> Self {
+		let InvoiceRequestWithDerivedPayerIdBuilder {
+			offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+		} = builder;
 
-	pub(super) fn build_unchecked(self) -> UnsignedInvoiceRequest {
-		self.build_without_checks().0
+		Self {
+			offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+		}
 	}
 }
 
@@ -368,6 +493,30 @@ pub struct UnsignedInvoiceRequest {
 	tagged_hash: TaggedHash,
 }
 
+/// A function for signing an [`UnsignedInvoiceRequest`].
+pub trait SignInvoiceRequestFn {
+	/// Signs a [`TaggedHash`] computed over the merkle root of `message`'s TLV stream.
+	fn sign_invoice_request(&self, message: &UnsignedInvoiceRequest) -> Result<Signature, ()>;
+}
+
+impl<F> SignInvoiceRequestFn for F
+where
+	F: Fn(&UnsignedInvoiceRequest) -> Result<Signature, ()>,
+{
+	fn sign_invoice_request(&self, message: &UnsignedInvoiceRequest) -> Result<Signature, ()> {
+		self(message)
+	}
+}
+
+impl<F> SignFn<UnsignedInvoiceRequest> for F
+where
+	F: SignInvoiceRequestFn,
+{
+	fn sign(&self, message: &UnsignedInvoiceRequest) -> Result<Signature, ()> {
+		self.sign_invoice_request(message)
+	}
+}
+
 impl UnsignedInvoiceRequest {
 	fn new(offer: &Offer, contents: InvoiceRequestContents) -> Self {
 		// Use the offer bytes instead of the offer TLV stream as the offer may have contained
@@ -380,7 +529,7 @@ impl UnsignedInvoiceRequest {
 		let mut bytes = Vec::new();
 		unsigned_tlv_stream.write(&mut bytes).unwrap();
 
-		let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);
+		let tagged_hash = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &bytes);
 
 		Self { bytes, contents, tagged_hash }
 	}
@@ -389,31 +538,48 @@ impl UnsignedInvoiceRequest {
 	pub fn tagged_hash(&self) -> &TaggedHash {
 		&self.tagged_hash
 	}
+}
 
+macro_rules! unsigned_invoice_request_sign_method { (
+	$self: ident, $self_type: ty $(, $self_mut: tt)?
+) => {
 	/// Signs the [`TaggedHash`] of the invoice request using the given function.
 	///
 	/// Note: The hash computation may have included unknown, odd TLV records.
-	///
-	/// This is not exported to bindings users as functions are not yet mapped.
-	pub fn sign<F, E>(mut self, sign: F) -> Result<InvoiceRequest, SignError<E>>
-	where
-		F: FnOnce(&Self) -> Result<Signature, E>
-	{
-		let pubkey = self.contents.payer_id;
-		let signature = merkle::sign_message(sign, &self, pubkey)?;
+	pub fn sign<F: SignInvoiceRequestFn>(
+		$($self_mut)* $self: $self_type, sign: F
+	) -> Result<InvoiceRequest, SignError> {
+		let pubkey = $self.contents.payer_id;
+		let signature = merkle::sign_message(sign, &$self, pubkey)?;
 
 		// Append the signature TLV record to the bytes.
 		let signature_tlv_stream = SignatureTlvStreamRef {
 			signature: Some(&signature),
 		};
-		signature_tlv_stream.write(&mut self.bytes).unwrap();
+		signature_tlv_stream.write(&mut $self.bytes).unwrap();
 
 		Ok(InvoiceRequest {
-			bytes: self.bytes,
-			contents: self.contents,
+			#[cfg(not(c_bindings))]
+			bytes: $self.bytes,
+			#[cfg(c_bindings)]
+			bytes: $self.bytes.clone(),
+			#[cfg(not(c_bindings))]
+			contents: $self.contents,
+			#[cfg(c_bindings)]
+			contents: $self.contents.clone(),
 			signature,
 		})
 	}
+} }
+
+#[cfg(not(c_bindings))]
+impl UnsignedInvoiceRequest {
+	unsigned_invoice_request_sign_method!(self, Self, mut);
+}
+
+#[cfg(c_bindings)]
+impl UnsignedInvoiceRequest {
+	unsigned_invoice_request_sign_method!(self, &mut Self);
 }
 
 impl AsRef<TaggedHash> for UnsignedInvoiceRequest {
@@ -441,6 +607,9 @@ pub struct InvoiceRequest {
 /// ways to respond depending on whether the signing keys were derived.
 #[derive(Clone, Debug)]
 pub struct VerifiedInvoiceRequest {
+	/// The identifier of the [`Offer`] for which the [`InvoiceRequest`] was made.
+	pub offer_id: OfferId,
+
 	/// The verified request.
 	inner: InvoiceRequest,
 
@@ -526,35 +695,25 @@ impl UnsignedInvoiceRequest {
 	invoice_request_accessors!(self, self.contents);
 }
 
-impl InvoiceRequest {
-	offer_accessors!(self, self.contents.inner.offer);
-	invoice_request_accessors!(self, self.contents);
-
-	/// Signature of the invoice request using [`payer_id`].
-	///
-	/// [`payer_id`]: Self::payer_id
-	pub fn signature(&self) -> Signature {
-		self.signature
-	}
-
+macro_rules! invoice_request_respond_with_explicit_signing_pubkey_methods { (
+	$self: ident, $contents: expr, $builder: ty
+) => {
 	/// Creates an [`InvoiceBuilder`] for the request with the given required fields and using the
 	/// [`Duration`] since [`std::time::SystemTime::UNIX_EPOCH`] as the creation time.
 	///
 	/// See [`InvoiceRequest::respond_with_no_std`] for further details where the aforementioned
 	/// creation time is used for the `created_at` parameter.
 	///
-	/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-	///
 	/// [`Duration`]: core::time::Duration
 	#[cfg(feature = "std")]
 	pub fn respond_with(
-		&self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
-	) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
+		&$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
+	) -> Result<$builder, Bolt12SemanticError> {
 		let created_at = std::time::SystemTime::now()
 			.duration_since(std::time::SystemTime::UNIX_EPOCH)
 			.expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
 
-		self.respond_with_no_std(payment_paths, payment_hash, created_at)
+		$contents.respond_with_no_std(payment_paths, payment_hash, created_at)
 	}
 
 	/// Creates an [`InvoiceBuilder`] for the request with the given required fields.
@@ -578,38 +737,94 @@ impl InvoiceRequest {
 	/// 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(
-		&self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
+		&$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
 		created_at: core::time::Duration
-	) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
-		if self.invoice_request_features().requires_unknown_bits() {
+	) -> Result<$builder, Bolt12SemanticError> {
+		if $contents.invoice_request_features().requires_unknown_bits() {
+			return Err(Bolt12SemanticError::UnknownRequiredFeatures);
+		}
+
+		let signing_pubkey = match $contents.contents.inner.offer.signing_pubkey() {
+			Some(signing_pubkey) => signing_pubkey,
+			None => return Err(Bolt12SemanticError::MissingSigningPubkey),
+		};
+
+		<$builder>::for_offer(&$contents, payment_paths, created_at, payment_hash, signing_pubkey)
+	}
+
+	#[cfg(test)]
+	#[allow(dead_code)]
+	pub(super) fn respond_with_no_std_using_signing_pubkey(
+		&$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
+		created_at: core::time::Duration, signing_pubkey: PublicKey
+	) -> Result<$builder, Bolt12SemanticError> {
+		debug_assert!($contents.contents.inner.offer.signing_pubkey().is_none());
+
+		if $contents.invoice_request_features().requires_unknown_bits() {
 			return Err(Bolt12SemanticError::UnknownRequiredFeatures);
 		}
 
-		InvoiceBuilder::for_offer(self, payment_paths, created_at, payment_hash)
+		<$builder>::for_offer(&$contents, payment_paths, created_at, payment_hash, signing_pubkey)
 	}
+} }
 
+macro_rules! invoice_request_verify_method { ($self: ident, $self_type: ty) => {
 	/// Verifies that the request was for an offer created using the given key. Returns the verified
 	/// request which contains the derived keys needed to sign a [`Bolt12Invoice`] for the request
 	/// if they could be extracted from the metadata.
 	///
 	/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
-	pub fn verify<T: secp256k1::Signing>(
-		self, 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)?;
+		let (offer_id, keys) = $self.contents.inner.offer.verify(&$self.bytes, key, secp_ctx)?;
 		Ok(VerifiedInvoiceRequest {
-			inner: self,
+			offer_id,
+			#[cfg(not(c_bindings))]
+			inner: $self,
+			#[cfg(c_bindings)]
+			inner: $self.clone(),
 			keys,
 		})
 	}
 
-	#[cfg(test)]
-	fn as_tlv_stream(&self) -> FullInvoiceRequestTlvStreamRef {
+} }
+
+#[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
+	pub fn signature(&self) -> Signature {
+		self.signature
+	}
+
+	pub(crate) fn as_tlv_stream(&self) -> FullInvoiceRequestTlvStreamRef {
 		let (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream) =
 			self.contents.as_tlv_stream();
 		let signature_tlv_stream = SignatureTlvStreamRef {
@@ -619,55 +834,25 @@ impl InvoiceRequest {
 	}
 }
 
-impl VerifiedInvoiceRequest {
-	offer_accessors!(self, self.inner.contents.inner.offer);
-	invoice_request_accessors!(self, self.inner.contents);
-
-	/// Creates an [`InvoiceBuilder`] for the request with the given required fields and using the
-	/// [`Duration`] since [`std::time::SystemTime::UNIX_EPOCH`] as the creation time.
-	///
-	/// 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.
-	///
-	/// [`Duration`]: core::time::Duration
-	#[cfg(feature = "std")]
-	pub fn respond_with(
-		&self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
-	) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
-		self.inner.respond_with(payment_paths, payment_hash)
-	}
-
-	/// Creates an [`InvoiceBuilder`] for the request with the given required fields.
-	///
-	/// 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.
-	pub fn respond_with_no_std(
-		&self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
-		created_at: core::time::Duration
-	) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
-		self.inner.respond_with_no_std(payment_paths, payment_hash, created_at)
-	}
-
+macro_rules! invoice_request_respond_with_derived_signing_pubkey_methods { (
+	$self: ident, $contents: expr, $builder: ty
+) => {
 	/// Creates an [`InvoiceBuilder`] for the request using the given required fields and that uses
 	/// derived signing keys from the originating [`Offer`] to sign the [`Bolt12Invoice`]. Must use
 	/// the same [`ExpandedKey`] as the one used to create the offer.
 	///
 	/// See [`InvoiceRequest::respond_with`] for further details.
 	///
-	/// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-	///
 	/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
 	#[cfg(feature = "std")]
 	pub fn respond_using_derived_keys(
-		&self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
-	) -> Result<InvoiceBuilder<DerivedSigningPubkey>, Bolt12SemanticError> {
+		&$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
+	) -> Result<$builder, Bolt12SemanticError> {
 		let created_at = std::time::SystemTime::now()
 			.duration_since(std::time::SystemTime::UNIX_EPOCH)
 			.expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
 
-		self.respond_using_derived_keys_no_std(payment_paths, payment_hash, created_at)
+		$self.respond_using_derived_keys_no_std(payment_paths, payment_hash, created_at)
 	}
 
 	/// Creates an [`InvoiceBuilder`] for the request using the given required fields and that uses
@@ -676,26 +861,60 @@ impl VerifiedInvoiceRequest {
 	///
 	/// 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,
+		&$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
 		created_at: core::time::Duration
-	) -> Result<InvoiceBuilder<DerivedSigningPubkey>, Bolt12SemanticError> {
-		if self.inner.invoice_request_features().requires_unknown_bits() {
+	) -> Result<$builder, Bolt12SemanticError> {
+		if $self.inner.invoice_request_features().requires_unknown_bits() {
 			return Err(Bolt12SemanticError::UnknownRequiredFeatures);
 		}
 
-		let keys = match self.keys {
+		let keys = match $self.keys {
 			None => return Err(Bolt12SemanticError::InvalidMetadata),
 			Some(keys) => keys,
 		};
 
-		InvoiceBuilder::for_offer_using_keys(
-			&self.inner, payment_paths, created_at, payment_hash, keys
+		match $contents.contents.inner.offer.signing_pubkey() {
+			Some(signing_pubkey) => debug_assert_eq!(signing_pubkey, keys.public_key()),
+			None => return Err(Bolt12SemanticError::MissingSigningPubkey),
+		}
+
+		<$builder>::for_offer_using_keys(
+			&$self.inner, payment_paths, created_at, payment_hash, keys
 		)
 	}
+} }
+
+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);
+
+	pub(crate) fn fields(&self) -> InvoiceRequestFields {
+		let InvoiceRequestContents {
+			payer_id,
+			inner: InvoiceRequestContentsWithoutPayerId {
+				payer: _, offer: _, chain: _, amount_msats, features, quantity, payer_note
+			},
+		} = &self.inner.contents;
+
+		InvoiceRequestFields {
+			payer_id: *payer_id,
+			amount_msats: *amount_msats,
+			features: features.clone(),
+			quantity: *quantity,
+			payer_note_truncated: payer_note.clone()
+				.map(|mut s| { s.truncate(PAYER_NOTE_LIMIT); UntrustedString(s) }),
+		}
+	}
 }
 
 impl InvoiceRequestContents {
@@ -767,6 +986,7 @@ impl InvoiceRequestContentsWithoutPayerId {
 			quantity: self.quantity,
 			payer_id: None,
 			payer_note: self.payer_note.as_ref(),
+			paths: None,
 		};
 
 		(payer, offer, invoice_request)
@@ -799,6 +1019,8 @@ pub(super) const INVOICE_REQUEST_TYPES: core::ops::Range<u64> = 80..160;
 /// [`Refund::payer_id`]: crate::offers::refund::Refund::payer_id
 pub(super) const INVOICE_REQUEST_PAYER_ID_TYPE: u64 = 88;
 
+// This TLV stream is used for both InvoiceRequest and Refund, but not all TLV records are valid for
+// InvoiceRequest as noted below.
 tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, INVOICE_REQUEST_TYPES, {
 	(80, chain: ChainHash),
 	(82, amount: (u64, HighZeroBytesDroppedBigSize)),
@@ -806,12 +1028,13 @@ tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, INVOICE_REQUEST
 	(86, quantity: (u64, HighZeroBytesDroppedBigSize)),
 	(INVOICE_REQUEST_PAYER_ID_TYPE, payer_id: PublicKey),
 	(89, payer_note: (String, WithoutLength)),
+	// Only used for Refund since the onion message of an InvoiceRequest has a reply path.
+	(90, paths: (Vec<BlindedPath>, WithoutLength)),
 });
 
 type FullInvoiceRequestTlvStream =
 	(PayerTlvStream, OfferTlvStream, InvoiceRequestTlvStream, SignatureTlvStream);
 
-#[cfg(test)]
 type FullInvoiceRequestTlvStreamRef<'a> = (
 	PayerTlvStreamRef<'a>,
 	OfferTlvStreamRef<'a>,
@@ -851,7 +1074,7 @@ impl TryFrom<Vec<u8>> for UnsignedInvoiceRequest {
 			(payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
 		)?;
 
-		let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);
+		let tagged_hash = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &bytes);
 
 		Ok(UnsignedInvoiceRequest { bytes, contents, tagged_hash })
 	}
@@ -875,8 +1098,8 @@ impl TryFrom<Vec<u8>> for InvoiceRequest {
 			None => return Err(Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSignature)),
 			Some(signature) => signature,
 		};
-		let message = TaggedHash::new(SIGNATURE_TAG, &bytes);
-		merkle::verify_signature(&signature, message, contents.payer_id)?;
+		let message = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &bytes);
+		merkle::verify_signature(&signature, &message, contents.payer_id)?;
 
 		Ok(InvoiceRequest { bytes, contents, signature })
 	}
@@ -889,7 +1112,9 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 		let (
 			PayerTlvStream { metadata },
 			offer_tlv_stream,
-			InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
+			InvoiceRequestTlvStream {
+				chain, amount, features, quantity, payer_id, payer_note, paths,
+			},
 		) = tlv_stream;
 
 		let payer = match metadata {
@@ -916,6 +1141,10 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 			Some(payer_id) => payer_id,
 		};
 
+		if paths.is_some() {
+			return Err(Bolt12SemanticError::UnexpectedPaths);
+		}
+
 		Ok(InvoiceRequestContents {
 			inner: InvoiceRequestContentsWithoutPayerId {
 				payer, offer, chain, amount_msats: amount, features, quantity, payer_note,
@@ -925,14 +1154,72 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
 	}
 }
 
+/// Fields sent in an [`InvoiceRequest`] message to include in [`PaymentContext::Bolt12Offer`].
+///
+/// [`PaymentContext::Bolt12Offer`]: crate::blinded_path::payment::PaymentContext::Bolt12Offer
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct InvoiceRequestFields {
+	/// A possibly transient pubkey used to sign the invoice request.
+	pub payer_id: PublicKey,
+
+	/// The amount to pay in msats (i.e., the minimum lightning-payable unit for [`chain`]), which
+	/// must be greater than or equal to [`Offer::amount`], converted if necessary.
+	///
+	/// [`chain`]: InvoiceRequest::chain
+	pub amount_msats: Option<u64>,
+
+	/// Features pertaining to requesting an invoice.
+	pub features: InvoiceRequestFeatures,
+
+	/// The quantity of the offer's item conforming to [`Offer::is_valid_quantity`].
+	pub quantity: Option<u64>,
+
+	/// A payer-provided note which will be seen by the recipient and reflected back in the invoice
+	/// response. Truncated to [`PAYER_NOTE_LIMIT`] characters.
+	pub payer_note_truncated: Option<UntrustedString>,
+}
+
+/// The maximum number of characters included in [`InvoiceRequestFields::payer_note_truncated`].
+pub const PAYER_NOTE_LIMIT: usize = 512;
+
+impl Writeable for InvoiceRequestFields {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		write_tlv_fields!(writer, {
+			(0, self.payer_id, required),
+			(2, self.amount_msats.map(|v| HighZeroBytesDroppedBigSize(v)), option),
+			(4, WithoutLength(&self.features), required),
+			(6, self.quantity.map(|v| HighZeroBytesDroppedBigSize(v)), option),
+			(8, self.payer_note_truncated.as_ref().map(|s| WithoutLength(&s.0)), option),
+		});
+		Ok(())
+	}
+}
+
+impl Readable for InvoiceRequestFields {
+	fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		_init_and_read_len_prefixed_tlv_fields!(reader, {
+			(0, payer_id, required),
+			(2, amount_msats, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+			(4, features, (option, encoding: (InvoiceRequestFeatures, WithoutLength))),
+			(6, quantity, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+			(8, payer_note_truncated, (option, encoding: (String, WithoutLength))),
+		});
+		let features = features.unwrap_or(InvoiceRequestFeatures::empty());
+
+		Ok(InvoiceRequestFields {
+			payer_id: payer_id.0.unwrap(), amount_msats, features, quantity,
+			payer_note_truncated: payer_note_truncated.map(|s| UntrustedString(s)),
+		})
+	}
+}
+
 #[cfg(test)]
 mod tests {
-	use super::{InvoiceRequest, InvoiceRequestTlvStreamRef, SIGNATURE_TAG, UnsignedInvoiceRequest};
+	use super::{InvoiceRequest, InvoiceRequestFields, InvoiceRequestTlvStreamRef, PAYER_NOTE_LIMIT, SIGNATURE_TAG, UnsignedInvoiceRequest};
 
 	use bitcoin::blockdata::constants::ChainHash;
 	use bitcoin::network::constants::Network;
 	use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey, self};
-	use core::convert::{Infallible, TryFrom};
 	use core::num::NonZeroU64;
 	#[cfg(feature = "std")]
 	use core::time::Duration;
@@ -943,20 +1230,30 @@ mod tests {
 	use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
 	use crate::offers::invoice::{Bolt12Invoice, SIGNATURE_TAG as INVOICE_SIGNATURE_TAG};
 	use crate::offers::merkle::{SignError, SignatureTlvStreamRef, TaggedHash, self};
-	use crate::offers::offer::{Amount, OfferBuilder, OfferTlvStreamRef, Quantity};
+	use crate::offers::offer::{Amount, OfferTlvStreamRef, Quantity};
+	#[cfg(not(c_bindings))]
+	use {
+		crate::offers::offer::OfferBuilder,
+	};
+	#[cfg(c_bindings)]
+	use {
+		crate::offers::offer::OfferWithExplicitMetadataBuilder as OfferBuilder,
+	};
 	use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError};
 	use crate::offers::payer::PayerTlvStreamRef;
 	use crate::offers::test_utils::*;
-	use crate::util::ser::{BigSize, Writeable};
-	use crate::util::string::PrintableString;
+	use crate::util::ser::{BigSize, Readable, Writeable};
+	use crate::util::string::{PrintableString, UntrustedString};
 
 	#[test]
 	fn builds_invoice_request_with_defaults() {
-		let unsigned_invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let unsigned_invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 			.build().unwrap();
+		#[cfg(c_bindings)]
+		let mut unsigned_invoice_request = unsigned_invoice_request;
 
 		let mut buffer = Vec::new();
 		unsigned_invoice_request.write(&mut buffer).unwrap();
@@ -966,13 +1263,13 @@ mod tests {
 		assert_eq!(unsigned_invoice_request.chains(), vec![ChainHash::using_genesis_block(Network::Bitcoin)]);
 		assert_eq!(unsigned_invoice_request.metadata(), None);
 		assert_eq!(unsigned_invoice_request.amount(), Some(&Amount::Bitcoin { amount_msats: 1000 }));
-		assert_eq!(unsigned_invoice_request.description(), PrintableString("foo"));
+		assert_eq!(unsigned_invoice_request.description(), Some(PrintableString("")));
 		assert_eq!(unsigned_invoice_request.offer_features(), &OfferFeatures::empty());
 		assert_eq!(unsigned_invoice_request.absolute_expiry(), None);
 		assert_eq!(unsigned_invoice_request.paths(), &[]);
 		assert_eq!(unsigned_invoice_request.issuer(), None);
 		assert_eq!(unsigned_invoice_request.supported_quantity(), Quantity::One);
-		assert_eq!(unsigned_invoice_request.signing_pubkey(), recipient_pubkey());
+		assert_eq!(unsigned_invoice_request.signing_pubkey(), Some(recipient_pubkey()));
 		assert_eq!(unsigned_invoice_request.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
 		assert_eq!(unsigned_invoice_request.amount_msats(), None);
 		assert_eq!(unsigned_invoice_request.invoice_request_features(), &InvoiceRequestFeatures::empty());
@@ -998,13 +1295,13 @@ mod tests {
 		assert_eq!(invoice_request.chains(), vec![ChainHash::using_genesis_block(Network::Bitcoin)]);
 		assert_eq!(invoice_request.metadata(), None);
 		assert_eq!(invoice_request.amount(), Some(&Amount::Bitcoin { amount_msats: 1000 }));
-		assert_eq!(invoice_request.description(), PrintableString("foo"));
+		assert_eq!(invoice_request.description(), Some(PrintableString("")));
 		assert_eq!(invoice_request.offer_features(), &OfferFeatures::empty());
 		assert_eq!(invoice_request.absolute_expiry(), None);
 		assert_eq!(invoice_request.paths(), &[]);
 		assert_eq!(invoice_request.issuer(), None);
 		assert_eq!(invoice_request.supported_quantity(), Quantity::One);
-		assert_eq!(invoice_request.signing_pubkey(), recipient_pubkey());
+		assert_eq!(invoice_request.signing_pubkey(), Some(recipient_pubkey()));
 		assert_eq!(invoice_request.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
 		assert_eq!(invoice_request.amount_msats(), None);
 		assert_eq!(invoice_request.invoice_request_features(), &InvoiceRequestFeatures::empty());
@@ -1012,8 +1309,8 @@ mod tests {
 		assert_eq!(invoice_request.payer_id(), payer_pubkey());
 		assert_eq!(invoice_request.payer_note(), None);
 
-		let message = TaggedHash::new(SIGNATURE_TAG, &invoice_request.bytes);
-		assert!(merkle::verify_signature(&invoice_request.signature, message, payer_pubkey()).is_ok());
+		let message = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &invoice_request.bytes);
+		assert!(merkle::verify_signature(&invoice_request.signature, &message, payer_pubkey()).is_ok());
 
 		assert_eq!(
 			invoice_request.as_tlv_stream(),
@@ -1024,7 +1321,7 @@ mod tests {
 					metadata: None,
 					currency: None,
 					amount: Some(1000),
-					description: Some(&String::from("foo")),
+					description: Some(&String::from("")),
 					features: None,
 					absolute_expiry: None,
 					paths: None,
@@ -1039,6 +1336,7 @@ mod tests {
 					quantity: None,
 					payer_id: Some(&payer_pubkey()),
 					payer_note: None,
+					paths: None,
 				},
 				SignatureTlvStreamRef { signature: Some(&invoice_request.signature()) },
 			),
@@ -1055,7 +1353,7 @@ mod tests {
 		let future_expiry = Duration::from_secs(u64::max_value());
 		let past_expiry = Duration::from_secs(0);
 
-		if let Err(e) = OfferBuilder::new("foo".into(), recipient_pubkey())
+		if let Err(e) = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.absolute_expiry(future_expiry)
 			.build().unwrap()
@@ -1065,7 +1363,7 @@ mod tests {
 			panic!("error building invoice_request: {:?}", e);
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.absolute_expiry(past_expiry)
 			.build().unwrap()
@@ -1085,7 +1383,7 @@ mod tests {
 		let secp_ctx = Secp256k1::new();
 		let payment_id = PaymentId([1; 32]);
 
-		let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let offer = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap();
 		let invoice_request = offer
@@ -1117,7 +1415,7 @@ mod tests {
 		let mut bytes = Vec::new();
 		tlv_stream.write(&mut bytes).unwrap();
 
-		let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+		let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
 		let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
 		signature_tlv_stream.signature = Some(&signature);
 
@@ -1140,7 +1438,7 @@ mod tests {
 		let mut bytes = Vec::new();
 		tlv_stream.write(&mut bytes).unwrap();
 
-		let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+		let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
 		let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
 		signature_tlv_stream.signature = Some(&signature);
 
@@ -1158,7 +1456,7 @@ mod tests {
 		let secp_ctx = Secp256k1::new();
 		let payment_id = PaymentId([1; 32]);
 
-		let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let offer = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap();
 		let invoice_request = offer
@@ -1189,7 +1487,7 @@ mod tests {
 		let mut bytes = Vec::new();
 		tlv_stream.write(&mut bytes).unwrap();
 
-		let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+		let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
 		let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
 		signature_tlv_stream.signature = Some(&signature);
 
@@ -1212,7 +1510,7 @@ mod tests {
 		let mut bytes = Vec::new();
 		tlv_stream.write(&mut bytes).unwrap();
 
-		let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+		let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
 		let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
 		signature_tlv_stream.signature = Some(&signature);
 
@@ -1228,7 +1526,7 @@ mod tests {
 		let mainnet = ChainHash::using_genesis_block(Network::Bitcoin);
 		let testnet = ChainHash::using_genesis_block(Network::Testnet);
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1239,7 +1537,7 @@ mod tests {
 		assert_eq!(invoice_request.chain(), mainnet);
 		assert_eq!(tlv_stream.chain, None);
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.chain(Network::Testnet)
 			.build().unwrap()
@@ -1251,7 +1549,7 @@ mod tests {
 		assert_eq!(invoice_request.chain(), testnet);
 		assert_eq!(tlv_stream.chain, Some(&testnet));
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.chain(Network::Bitcoin)
 			.chain(Network::Testnet)
@@ -1264,7 +1562,7 @@ mod tests {
 		assert_eq!(invoice_request.chain(), mainnet);
 		assert_eq!(tlv_stream.chain, None);
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.chain(Network::Bitcoin)
 			.chain(Network::Testnet)
@@ -1278,7 +1576,7 @@ mod tests {
 		assert_eq!(invoice_request.chain(), testnet);
 		assert_eq!(tlv_stream.chain, Some(&testnet));
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.chain(Network::Testnet)
 			.build().unwrap()
@@ -1289,7 +1587,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::UnsupportedChain),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.chain(Network::Testnet)
 			.build().unwrap()
@@ -1303,7 +1601,7 @@ mod tests {
 
 	#[test]
 	fn builds_invoice_request_with_amount() {
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1314,7 +1612,7 @@ mod tests {
 		assert_eq!(invoice_request.amount_msats(), Some(1000));
 		assert_eq!(tlv_stream.amount, Some(1000));
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1326,7 +1624,7 @@ mod tests {
 		assert_eq!(invoice_request.amount_msats(), Some(1000));
 		assert_eq!(tlv_stream.amount, Some(1000));
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1337,7 +1635,7 @@ mod tests {
 		assert_eq!(invoice_request.amount_msats(), Some(1001));
 		assert_eq!(tlv_stream.amount, Some(1001));
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1347,7 +1645,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1359,7 +1657,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1369,7 +1667,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidAmount),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1382,7 +1680,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 			.build()
@@ -1391,7 +1689,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::MissingAmount),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1406,7 +1704,7 @@ mod tests {
 
 	#[test]
 	fn builds_invoice_request_with_features() {
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1417,7 +1715,7 @@ mod tests {
 		assert_eq!(invoice_request.invoice_request_features(), &InvoiceRequestFeatures::unknown());
 		assert_eq!(tlv_stream.features, Some(&InvoiceRequestFeatures::unknown()));
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1435,7 +1733,7 @@ mod tests {
 		let one = NonZeroU64::new(1).unwrap();
 		let ten = NonZeroU64::new(10).unwrap();
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::One)
 			.build().unwrap()
@@ -1446,7 +1744,7 @@ mod tests {
 		assert_eq!(invoice_request.quantity(), None);
 		assert_eq!(tlv_stream.quantity, None);
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::One)
 			.build().unwrap()
@@ -1458,7 +1756,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::UnexpectedQuantity),
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Bounded(ten))
 			.build().unwrap()
@@ -1471,7 +1769,7 @@ mod tests {
 		assert_eq!(invoice_request.amount_msats(), Some(10_000));
 		assert_eq!(tlv_stream.amount, Some(10_000));
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Bounded(ten))
 			.build().unwrap()
@@ -1483,7 +1781,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidQuantity),
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1496,7 +1794,7 @@ mod tests {
 		assert_eq!(invoice_request.amount_msats(), Some(2_000));
 		assert_eq!(tlv_stream.amount, Some(2_000));
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1507,7 +1805,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12SemanticError::MissingQuantity),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Bounded(one))
 			.build().unwrap()
@@ -1521,7 +1819,7 @@ mod tests {
 
 	#[test]
 	fn builds_invoice_request_with_payer_note() {
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1532,7 +1830,7 @@ mod tests {
 		assert_eq!(invoice_request.payer_note(), Some(PrintableString("bar")));
 		assert_eq!(tlv_stream.payer_note, Some(&String::from("bar")));
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1547,18 +1845,18 @@ mod tests {
 
 	#[test]
 	fn fails_signing_invoice_request() {
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 			.build().unwrap()
-			.sign(|_| Err(()))
+			.sign(fail_sign)
 		{
 			Ok(_) => panic!("expected error"),
-			Err(e) => assert_eq!(e, SignError::Signing(())),
+			Err(e) => assert_eq!(e, SignError::Signing),
 		}
 
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1572,7 +1870,7 @@ mod tests {
 
 	#[test]
 	fn fails_responding_with_unknown_required_features() {
-		match OfferBuilder::new("foo".into(), recipient_pubkey())
+		match OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![42; 32], payer_pubkey()).unwrap()
@@ -1588,7 +1886,7 @@ mod tests {
 
 	#[test]
 	fn parses_invoice_request_with_metadata() {
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1605,7 +1903,7 @@ mod tests {
 
 	#[test]
 	fn parses_invoice_request_with_chain() {
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1620,7 +1918,7 @@ mod tests {
 			panic!("error parsing invoice_request: {:?}", e);
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1639,7 +1937,7 @@ mod tests {
 
 	#[test]
 	fn parses_invoice_request_with_amount() {
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1653,7 +1951,7 @@ mod tests {
 			panic!("error parsing invoice_request: {:?}", e);
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 			.amount_msats(1000).unwrap()
@@ -1667,7 +1965,7 @@ mod tests {
 			panic!("error parsing invoice_request: {:?}", e);
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
 			.build_unchecked()
@@ -1681,7 +1979,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingAmount)),
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1697,7 +1995,8 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InsufficientAmount)),
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
+			.description("foo".to_string())
 			.amount(Amount::Currency { iso4217_code: *b"USD", amount: 1000 })
 			.build_unchecked()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1714,7 +2013,7 @@ mod tests {
 			},
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1737,7 +2036,7 @@ mod tests {
 		let one = NonZeroU64::new(1).unwrap();
 		let ten = NonZeroU64::new(10).unwrap();
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::One)
 			.build().unwrap()
@@ -1752,7 +2051,7 @@ mod tests {
 			panic!("error parsing invoice_request: {:?}", e);
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::One)
 			.build().unwrap()
@@ -1772,7 +2071,7 @@ mod tests {
 			},
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Bounded(ten))
 			.build().unwrap()
@@ -1789,7 +2088,7 @@ mod tests {
 			panic!("error parsing invoice_request: {:?}", e);
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Bounded(ten))
 			.build().unwrap()
@@ -1807,7 +2106,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidQuantity)),
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1824,7 +2123,7 @@ mod tests {
 			panic!("error parsing invoice_request: {:?}", e);
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Unbounded)
 			.build().unwrap()
@@ -1840,7 +2139,7 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingQuantity)),
 		}
 
-		let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.supported_quantity(Quantity::Bounded(one))
 			.build().unwrap()
@@ -1859,7 +2158,7 @@ mod tests {
 
 	#[test]
 	fn fails_parsing_invoice_request_without_metadata() {
-		let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let offer = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap();
 		let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1880,7 +2179,7 @@ mod tests {
 
 	#[test]
 	fn fails_parsing_invoice_request_without_payer_id() {
-		let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let offer = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap();
 		let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1899,7 +2198,7 @@ mod tests {
 
 	#[test]
 	fn fails_parsing_invoice_request_without_node_id() {
-		let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let offer = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap();
 		let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1921,7 +2220,7 @@ mod tests {
 	#[test]
 	fn fails_parsing_invoice_request_without_signature() {
 		let mut buffer = Vec::new();
-		OfferBuilder::new("foo".into(), recipient_pubkey())
+		OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1937,7 +2236,7 @@ mod tests {
 
 	#[test]
 	fn fails_parsing_invoice_request_with_invalid_signature() {
-		let mut invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+		let mut invoice_request = OfferBuilder::new(recipient_pubkey())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1961,13 +2260,13 @@ mod tests {
 	fn fails_parsing_invoice_request_with_extra_tlv_records() {
 		let secp_ctx = Secp256k1::new();
 		let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
-		let invoice_request = OfferBuilder::new("foo".into(), keys.public_key())
+		let invoice_request = OfferBuilder::new(keys.public_key())
 			.amount_msats(1000)
 			.build().unwrap()
 			.request_invoice(vec![1; 32], keys.public_key()).unwrap()
 			.build().unwrap()
-			.sign::<_, Infallible>(
-				|message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+			.sign(|message: &UnsignedInvoiceRequest|
+				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
 			)
 			.unwrap();
 
@@ -1982,4 +2281,54 @@ mod tests {
 			Err(e) => assert_eq!(e, Bolt12ParseError::Decode(DecodeError::InvalidValue)),
 		}
 	}
+
+	#[test]
+	fn copies_verified_invoice_request_fields() {
+		let node_id = recipient_pubkey();
+		let expanded_key = ExpandedKey::new(&KeyMaterial([42; 32]));
+		let entropy = FixedEntropy {};
+		let secp_ctx = Secp256k1::new();
+
+		#[cfg(c_bindings)]
+		use crate::offers::offer::OfferWithDerivedMetadataBuilder as OfferBuilder;
+		let offer = OfferBuilder
+			::deriving_signing_pubkey(node_id, &expanded_key, &entropy, &secp_ctx)
+			.chain(Network::Testnet)
+			.amount_msats(1000)
+			.supported_quantity(Quantity::Unbounded)
+			.build().unwrap();
+		assert_eq!(offer.signing_pubkey(), Some(node_id));
+
+		let invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+			.chain(Network::Testnet).unwrap()
+			.amount_msats(1001).unwrap()
+			.quantity(1).unwrap()
+			.payer_note("0".repeat(PAYER_NOTE_LIMIT * 2))
+			.build().unwrap()
+			.sign(payer_sign).unwrap();
+		match invoice_request.verify(&expanded_key, &secp_ctx) {
+			Ok(invoice_request) => {
+				let fields = invoice_request.fields();
+				assert_eq!(invoice_request.offer_id, offer.id());
+				assert_eq!(
+					fields,
+					InvoiceRequestFields {
+						payer_id: payer_pubkey(),
+						amount_msats: Some(1001),
+						features: InvoiceRequestFeatures::empty(),
+						quantity: Some(1),
+						payer_note_truncated: Some(UntrustedString("0".repeat(PAYER_NOTE_LIMIT))),
+					}
+				);
+
+				let mut buffer = Vec::new();
+				fields.write(&mut buffer).unwrap();
+
+				let deserialized_fields: InvoiceRequestFields =
+					Readable::read(&mut buffer.as_slice()).unwrap();
+				assert_eq!(deserialized_fields, fields);
+			},
+			Err(_) => panic!("unexpected error"),
+		}
+	}
 }