Support BOLT 12 signing in c_bindings

[rust-lightning] / lightning / src / offers / invoice.rs

diff --git a/lightning/src/offers/invoice.rs b/lightning/src/offers/invoice.rs
index f665bd3b26e81dda6c2181e15dc2f46758f84a9f..50406738f36ff9d3e8d8bd783fd7196bf78d335d 100644 (file)
--- a/lightning/src/offers/invoice.rs
+++ b/lightning/src/offers/invoice.rs
@@ -23,6 +23,7 @@
 //! use bitcoin::hashes::Hash;
 //! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
 //! use core::convert::{Infallible, TryFrom};
+//! use lightning::offers::invoice::UnsignedBolt12Invoice;
 //! use lightning::offers::invoice_request::InvoiceRequest;
 //! use lightning::offers::refund::Refund;
 //! use lightning::util::ser::Writeable;
@@ -57,9 +58,9 @@
 //!     .allow_mpp()
 //!     .fallback_v0_p2wpkh(&wpubkey_hash)
 //!     .build()?
-//!     .sign::<_, Infallible>(
-//!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-//!     )
+//!     .sign(|message: &UnsignedBolt12Invoice| -> Result<_, Infallible> {
+//!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+//!     })
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
 //!     .unwrap();
@@ -90,9 +91,9 @@
 //!     .allow_mpp()
 //!     .fallback_v0_p2wpkh(&wpubkey_hash)
 //!     .build()?
-//!     .sign::<_, Infallible>(
-//!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-//!     )
+//!     .sign(|message: &UnsignedBolt12Invoice| -> Result<_, Infallible> {
+//!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+//!     })
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
 //!     .unwrap();
@@ -119,7 +120,7 @@ use crate::ln::features::{BlindedHopFeatures, Bolt12InvoiceFeatures, InvoiceRequ
 use crate::ln::inbound_payment::ExpandedKey;
 use crate::ln::msgs::DecodeError;
 use crate::offers::invoice_request::{INVOICE_REQUEST_PAYER_ID_TYPE, INVOICE_REQUEST_TYPES, IV_BYTES as INVOICE_REQUEST_IV_BYTES, InvoiceRequest, InvoiceRequestContents, InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef};
-use crate::offers::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, TlvStream, WithoutSignatures, self};
+use crate::offers::merkle::{SignError, SignFn, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, TlvStream, WithoutSignatures, self};
 use crate::offers::offer::{Amount, OFFER_TYPES, OfferTlvStream, OfferTlvStreamRef, Quantity};
 use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError, ParsedMessage};
 use crate::offers::payer::{PAYER_METADATA_TYPE, PayerTlvStream, PayerTlvStreamRef};
@@ -324,9 +325,9 @@ macro_rules! invoice_derived_signing_pubkey_builder_methods { ($self: ident, $se
                let mut unsigned_invoice = UnsignedBolt12Invoice::new(invreq_bytes, invoice.clone());
 
                let invoice = unsigned_invoice
-                       .sign::<_, Infallible>(
-                               |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-                       )
+                       .sign(|message: &UnsignedBolt12Invoice| -> Result<_, Infallible> {
+                               Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+                       })
                        .unwrap();
                Ok(invoice)
        }
@@ -507,6 +508,37 @@ pub struct UnsignedBolt12Invoice {
        tagged_hash: TaggedHash,
 }
 
+/// A function for signing an [`UnsignedBolt12Invoice`].
+pub trait SignBolt12InvoiceFn {
+       /// Error type returned by the function.
+       type Error;
+
+       /// Signs a [`TaggedHash`] computed over the merkle root of `message`'s TLV stream.
+       fn sign_invoice(&self, message: &UnsignedBolt12Invoice) -> Result<Signature, Self::Error>;
+}
+
+impl<F, E> SignBolt12InvoiceFn for F
+where
+       F: Fn(&UnsignedBolt12Invoice) -> Result<Signature, E>,
+{
+       type Error = E;
+
+       fn sign_invoice(&self, message: &UnsignedBolt12Invoice) -> Result<Signature, E> {
+               self(message)
+       }
+}
+
+impl<F, E> SignFn<UnsignedBolt12Invoice> for F
+where
+       F: SignBolt12InvoiceFn<Error = E>,
+{
+       type Error = E;
+
+       fn sign(&self, message: &UnsignedBolt12Invoice) -> Result<Signature, Self::Error> {
+               self.sign_invoice(message)
+       }
+}
+
 impl UnsignedBolt12Invoice {
        fn new(invreq_bytes: &[u8], contents: InvoiceContents) -> Self {
                // Use the invoice_request bytes instead of the invoice_request TLV stream as the latter may
@@ -534,12 +566,9 @@ macro_rules! unsigned_invoice_sign_method { ($self: ident, $self_type: ty $(, $s
        /// Signs the [`TaggedHash`] of the invoice using the given function.
        ///
        /// Note: The hash computation may have included unknown, odd TLV records.
-       ///
-       /// This is not exported to bindings users as functions aren't currently mapped.
-       pub fn sign<F, E>($($self_mut)* $self: $self_type, sign: F) -> Result<Bolt12Invoice, SignError<E>>
-       where
-               F: FnOnce(&Self) -> Result<Signature, E>
-       {
+       pub fn sign<F: SignBolt12InvoiceFn>(
+               $($self_mut)* $self: $self_type, sign: F
+       ) -> Result<Bolt12Invoice, SignError<F::Error>> {
                let pubkey = $self.contents.fields().signing_pubkey;
                let signature = merkle::sign_message(sign, &$self, pubkey)?;
 
@@ -2013,7 +2042,7 @@ mod tests {
                        .sign(payer_sign).unwrap()
                        .respond_with_no_std(payment_paths(), payment_hash(), now()).unwrap()
                        .build().unwrap()
-                       .sign(|_| Err(()))
+                       .sign(fail_sign)
                {
                        Ok(_) => panic!("expected error"),
                        Err(e) => assert_eq!(e, SignError::Signing(())),