Builder for creating invoice requests
[rust-lightning] / lightning / src / offers / offer.rs
index 1403fbd223ec19ab8888f0e2fdaae8432dcd0cb8..d890ab3f642cfb14fffe70f843b3086f8688fdcb 100644 (file)
@@ -76,6 +76,7 @@ use core::time::Duration;
 use crate::io;
 use crate::ln::features::OfferFeatures;
 use crate::ln::msgs::MAX_VALUE_MSAT;
+use crate::offers::invoice_request::InvoiceRequestBuilder;
 use crate::offers::parse::{Bech32Encode, ParseError, ParsedMessage, SemanticError};
 use crate::onion_message::BlindedPath;
 use crate::util::ser::{HighZeroBytesDroppedBigSize, WithoutLength, Writeable, Writer};
@@ -149,15 +150,6 @@ impl OfferBuilder {
                self
        }
 
-       /// Sets the [`Offer::features`].
-       ///
-       /// Successive calls to this method will override the previous setting.
-       #[cfg(test)]
-       pub fn features(mut self, features: OfferFeatures) -> Self {
-               self.offer.features = features;
-               self
-       }
-
        /// Sets the [`Offer::absolute_expiry`] as seconds since the Unix epoch. Any expiry that has
        /// already passed is valid and can be checked for using [`Offer::is_expired`].
        ///
@@ -222,6 +214,14 @@ impl OfferBuilder {
        }
 }
 
+#[cfg(test)]
+impl OfferBuilder {
+       fn features_unchecked(mut self, features: OfferFeatures) -> Self {
+               self.offer.features = features;
+               self
+       }
+}
+
 /// An `Offer` is a potentially long-lived proposal for payment of a good or service.
 ///
 /// An offer is a precursor to an [`InvoiceRequest`]. A merchant publishes an offer from which a
@@ -238,8 +238,8 @@ impl OfferBuilder {
 pub struct Offer {
        // The serialized offer. Needed when creating an `InvoiceRequest` if the offer contains unknown
        // fields.
-       bytes: Vec<u8>,
-       contents: OfferContents,
+       pub(super) bytes: Vec<u8>,
+       pub(super) contents: OfferContents,
 }
 
 /// The contents of an [`Offer`], which may be shared with an [`InvoiceRequest`] or an `Invoice`.
@@ -270,6 +270,10 @@ impl Offer {
                self.contents.chains()
        }
 
+       pub(super) fn implied_chain(&self) -> ChainHash {
+               self.contents.implied_chain()
+       }
+
        /// Returns whether the given chain is supported by the offer.
        pub fn supports_chain(&self, chain: ChainHash) -> bool {
                self.contents.supports_chain(chain)
@@ -351,6 +355,29 @@ impl Offer {
                self.contents.signing_pubkey.unwrap()
        }
 
+       /// Creates an [`InvoiceRequest`] for the offer with the given `metadata` and `payer_id`, which
+       /// will be reflected in the `Invoice` response.
+       ///
+       /// The `metadata` is useful for including information about the derivation of `payer_id` such
+       /// that invoice response handling can be stateless. Also serves as payer-provided entropy while
+       /// hashing in the signature calculation.
+       ///
+       /// This should not leak any information such as by using a simple BIP-32 derivation path.
+       /// Otherwise, payments may be correlated.
+       ///
+       /// Errors if the offer contains unknown required features.
+       ///
+       /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+       pub fn request_invoice(
+               &self, metadata: Vec<u8>, payer_id: PublicKey
+       ) -> Result<InvoiceRequestBuilder, SemanticError> {
+               if self.features().requires_unknown_bits() {
+                       return Err(SemanticError::UnknownRequiredFeatures);
+               }
+
+               Ok(InvoiceRequestBuilder::new(self, metadata, payer_id))
+       }
+
        #[cfg(test)]
        fn as_tlv_stream(&self) -> OfferTlvStreamRef {
                self.contents.as_tlv_stream()
@@ -380,23 +407,48 @@ impl OfferContents {
                self.amount.as_ref()
        }
 
-       pub fn amount_msats(&self) -> u64 {
-               match self.amount() {
+       pub(super) fn check_amount_msats_for_quantity(
+               &self, amount_msats: Option<u64>, quantity: Option<u64>
+       ) -> Result<(), SemanticError> {
+               let offer_amount_msats = match self.amount {
                        None => 0,
-                       Some(&Amount::Bitcoin { amount_msats }) => amount_msats,
-                       Some(&Amount::Currency { .. }) => unreachable!(),
+                       Some(Amount::Bitcoin { amount_msats }) => amount_msats,
+                       Some(Amount::Currency { .. }) => return Err(SemanticError::UnsupportedCurrency),
+               };
+
+               if !self.expects_quantity() || quantity.is_some() {
+                       let expected_amount_msats = offer_amount_msats * quantity.unwrap_or(1);
+                       let amount_msats = amount_msats.unwrap_or(expected_amount_msats);
+
+                       if amount_msats < expected_amount_msats {
+                               return Err(SemanticError::InsufficientAmount);
+                       }
+
+                       if amount_msats > MAX_VALUE_MSAT {
+                               return Err(SemanticError::InvalidAmount);
+                       }
                }
-       }
 
-       pub fn expected_invoice_amount_msats(&self, quantity: u64) -> u64 {
-               self.amount_msats() * quantity
+               Ok(())
        }
 
        pub fn supported_quantity(&self) -> Quantity {
                self.supported_quantity
        }
 
-       pub fn is_valid_quantity(&self, quantity: u64) -> bool {
+       pub(super) fn check_quantity(&self, quantity: Option<u64>) -> Result<(), SemanticError> {
+               let expects_quantity = self.expects_quantity();
+               match quantity {
+                       None if expects_quantity => Err(SemanticError::MissingQuantity),
+                       Some(_) if !expects_quantity => Err(SemanticError::UnexpectedQuantity),
+                       Some(quantity) if !self.is_valid_quantity(quantity) => {
+                               Err(SemanticError::InvalidQuantity)
+                       },
+                       _ => Ok(()),
+               }
+       }
+
+       fn is_valid_quantity(&self, quantity: u64) -> bool {
                match self.supported_quantity {
                        Quantity::Bounded(n) => {
                                let n = n.get();
@@ -407,14 +459,14 @@ impl OfferContents {
                }
        }
 
-       pub fn expects_quantity(&self) -> bool {
+       fn expects_quantity(&self) -> bool {
                match self.supported_quantity {
                        Quantity::Bounded(n) => n.get() != 1,
                        Quantity::Unbounded => true,
                }
        }
 
-       fn as_tlv_stream(&self) -> OfferTlvStreamRef {
+       pub(super) fn as_tlv_stream(&self) -> OfferTlvStreamRef {
                let (currency, amount) = match &self.amount {
                        None => (None, None),
                        Some(Amount::Bitcoin { amount_msats }) => (None, Some(*amount_msats)),
@@ -760,15 +812,15 @@ mod tests {
        #[test]
        fn builds_offer_with_features() {
                let offer = OfferBuilder::new("foo".into(), pubkey(42))
-                       .features(OfferFeatures::unknown())
+                       .features_unchecked(OfferFeatures::unknown())
                        .build()
                        .unwrap();
                assert_eq!(offer.features(), &OfferFeatures::unknown());
                assert_eq!(offer.as_tlv_stream().features, Some(&OfferFeatures::unknown()));
 
                let offer = OfferBuilder::new("foo".into(), pubkey(42))
-                       .features(OfferFeatures::unknown())
-                       .features(OfferFeatures::empty())
+                       .features_unchecked(OfferFeatures::unknown())
+                       .features_unchecked(OfferFeatures::empty())
                        .build()
                        .unwrap();
                assert_eq!(offer.features(), &OfferFeatures::empty());
@@ -890,6 +942,18 @@ mod tests {
                assert_eq!(tlv_stream.quantity_max, None);
        }
 
+       #[test]
+       fn fails_requesting_invoice_with_unknown_required_features() {
+               match OfferBuilder::new("foo".into(), pubkey(42))
+                       .features_unchecked(OfferFeatures::unknown())
+                       .build().unwrap()
+                       .request_invoice(vec![1; 32], pubkey(43))
+               {
+                       Ok(_) => panic!("expected error"),
+                       Err(e) => assert_eq!(e, SemanticError::UnknownRequiredFeatures),
+               }
+       }
+
        #[test]
        fn parses_offer_with_chains() {
                let offer = OfferBuilder::new("foo".into(), pubkey(42))