Add InvoiceError message

If an InvoiceRequest or an Invoice delivered via an onion message cannot
be handled, the recipient should reply with an InvoiceError if a reply
path was given. Define the message and conversion from SemanticError.

Author: jkczyz

lightning/src/offers/invoice_error.rs

@@ -0,0 +1,233 @@
+// 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.
+
+//! Data structures and encoding for `invoice_error` messages.
+
+use crate::io;
+use crate::ln::msgs::DecodeError;
+use crate::offers::parse::SemanticError;
+use crate::util::ser::{HighZeroBytesDroppedBigSize, Readable, WithoutLength, Writeable, Writer};
+use crate::util::string::UntrustedString;
+
+use crate::prelude::*;
+
+/// An error in response to an [`InvoiceRequest`] or an [`Invoice`].
+///
+/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+/// [`Invoice`]: crate::offers::invoice::Invoice
+#[derive(Clone, Debug)]
+#[cfg_attr(test, derive(PartialEq))]
+pub struct InvoiceError {
+	/// The field in the [`InvoiceRequest`] or the [`Invoice`] that contained an error.
+	///
+	/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+	/// [`Invoice`]: crate::offers::invoice::Invoice
+	pub erroneous_field: Option<ErroneousField>,
+
+	/// An explanation of the error.
+	pub message: UntrustedString,
+}
+
+/// The field in the [`InvoiceRequest`] or the [`Invoice`] that contained an error.
+///
+/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
+/// [`Invoice`]: crate::offers::invoice::Invoice
+#[derive(Clone, Debug)]
+#[cfg_attr(test, derive(PartialEq))]
+pub struct ErroneousField {
+	/// The type number of the TLV field containing the error.
+	pub tlv_fieldnum: u64,
+
+	/// A value to use for the TLV field to avoid the error.
+	pub suggested_value: Option<Vec<u8>>,
+}
+
+impl core::fmt::Display for InvoiceError {
+	fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
+		self.message.fmt(f)
+	}
+}
+
+impl Writeable for InvoiceError {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		let tlv_fieldnum = self.erroneous_field.as_ref().map(|f| f.tlv_fieldnum);
+		let suggested_value =
+			self.erroneous_field.as_ref().and_then(|f| f.suggested_value.as_ref());
+		write_tlv_fields!(writer, {
+			(1, tlv_fieldnum, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+			(3, suggested_value, (option, encoding: (Vec<u8>, WithoutLength))),
+			(5, WithoutLength(&self.message), required),
+		});
+		Ok(())
+	}
+}
+
+impl Readable for InvoiceError {
+	fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		_init_and_read_tlv_fields!(reader, {
+			(1, erroneous_field, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+			(3, suggested_value, (option, encoding: (Vec<u8>, WithoutLength))),
+			(5, error, (option, encoding: (UntrustedString, WithoutLength))),
+		});
+
+		let erroneous_field = match (erroneous_field, suggested_value) {
+			(None, None) => None,
+			(None, Some(_)) => return Err(DecodeError::InvalidValue),
+			(Some(tlv_fieldnum), suggested_value) => {
+				Some(ErroneousField { tlv_fieldnum, suggested_value })
+			},
+		};
+
+		let message = match error {
+			None => return Err(DecodeError::InvalidValue),
+			Some(error) => error,
+		};
+
+		Ok(InvoiceError { erroneous_field, message })
+	}
+}
+
+impl From<SemanticError> for InvoiceError {
+	fn from(error: SemanticError) -> Self {
+		InvoiceError {
+			erroneous_field: None,
+			message: UntrustedString(format!("{:?}", error)),
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::{ErroneousField, InvoiceError};
+
+	use crate::ln::msgs::DecodeError;
+	use crate::util::ser::{HighZeroBytesDroppedBigSize, Readable, VecWriter, WithoutLength, Writeable};
+	use crate::util::string::UntrustedString;
+
+	#[test]
+	fn parses_invoice_error_without_erroneous_field() {
+		let mut writer = VecWriter(Vec::new());
+		let invoice_error = InvoiceError {
+			erroneous_field: None,
+			message: UntrustedString("Invalid value".to_string()),
+		};
+		invoice_error.write(&mut writer).unwrap();
+
+		let buffer = writer.0;
+		match InvoiceError::read(&mut &buffer[..]) {
+			Ok(invoice_error) => {
+				assert_eq!(invoice_error.message, UntrustedString("Invalid value".to_string()));
+				assert_eq!(invoice_error.erroneous_field, None);
+			}
+			Err(e) => panic!("Unexpected error: {:?}", e),
+		}
+	}
+
+	#[test]
+	fn parses_invoice_error_with_erroneous_field() {
+		let mut writer = VecWriter(Vec::new());
+		let invoice_error = InvoiceError {
+			erroneous_field: Some(ErroneousField {
+				tlv_fieldnum: 42,
+				suggested_value: Some(vec![42; 32]),
+			}),
+			message: UntrustedString("Invalid value".to_string()),
+		};
+		invoice_error.write(&mut writer).unwrap();
+
+		let buffer = writer.0;
+		match InvoiceError::read(&mut &buffer[..]) {
+			Ok(invoice_error) => {
+				assert_eq!(invoice_error.message, UntrustedString("Invalid value".to_string()));
+				assert_eq!(
+					invoice_error.erroneous_field,
+					Some(ErroneousField { tlv_fieldnum: 42, suggested_value: Some(vec![42; 32]) }),
+				);
+			}
+			Err(e) => panic!("Unexpected error: {:?}", e),
+		}
+	}
+
+	#[test]
+	fn parses_invoice_error_without_suggested_value() {
+		let mut writer = VecWriter(Vec::new());
+		let invoice_error = InvoiceError {
+			erroneous_field: Some(ErroneousField {
+				tlv_fieldnum: 42,
+				suggested_value: None,
+			}),
+			message: UntrustedString("Invalid value".to_string()),
+		};
+		invoice_error.write(&mut writer).unwrap();
+
+		let buffer = writer.0;
+		match InvoiceError::read(&mut &buffer[..]) {
+			Ok(invoice_error) => {
+				assert_eq!(invoice_error.message, UntrustedString("Invalid value".to_string()));
+				assert_eq!(
+					invoice_error.erroneous_field,
+					Some(ErroneousField { tlv_fieldnum: 42, suggested_value: None }),
+				);
+			}
+			Err(e) => panic!("Unexpected error: {:?}", e),
+		}
+	}
+
+	#[test]
+	fn fails_parsing_invoice_error_without_message() {
+		let tlv_fieldnum: Option<u64> = None;
+		let suggested_value: Option<&Vec<u8>> = None;
+		let error: Option<&String> = None;
+
+		let mut writer = VecWriter(Vec::new());
+		let mut write_tlv = || -> Result<(), DecodeError> {
+			write_tlv_fields!(&mut writer, {
+				(1, tlv_fieldnum, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+				(3, suggested_value, (option, encoding: (Vec<u8>, WithoutLength))),
+				(5, error, (option, encoding: (String, WithoutLength))),
+			});
+			Ok(())
+		};
+		write_tlv().unwrap();
+
+		let buffer = writer.0;
+		match InvoiceError::read(&mut &buffer[..]) {
+			Ok(_) => panic!("Expected error"),
+			Err(e) => {
+				assert_eq!(e, DecodeError::InvalidValue);
+			},
+		}
+	}
+
+	#[test]
+	fn fails_parsing_invoice_error_without_field() {
+		let tlv_fieldnum: Option<u64> = None;
+		let suggested_value = vec![42; 32];
+		let error = "Invalid value".to_string();
+
+		let mut writer = VecWriter(Vec::new());
+		let mut write_tlv = || -> Result<(), DecodeError> {
+			write_tlv_fields!(&mut writer, {
+				(1, tlv_fieldnum, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+				(3, Some(&suggested_value), (option, encoding: (Vec<u8>, WithoutLength))),
+				(5, Some(&error), (option, encoding: (String, WithoutLength))),
+			});
+			Ok(())
+		};
+		write_tlv().unwrap();
+
+		let buffer = writer.0;
+		match InvoiceError::read(&mut &buffer[..]) {
+			Ok(_) => panic!("Expected error"),
+			Err(e) => {
+				assert_eq!(e, DecodeError::InvalidValue);
+			},
+		}
+	}
+}

lightning/src/offers/mod.rs

@@ -13,6 +13,7 @@
 //! Offers are a flexible protocol for Lightning payments.
 
 pub mod invoice;
+pub mod invoice_error;
 pub mod invoice_request;
 mod merkle;
 pub mod offer;

lightning/src/util/ser_macros.rs

@@ -178,6 +178,9 @@ macro_rules! _get_varint_length_prefixed_tlv_length {
 	($len: expr, $type: expr, $field: expr, (option: $trait: ident $(, $read_arg: expr)?)) => {
 		$crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, option);
 	};
+	($len: expr, $type: expr, $field: expr, (option, encoding: ($fieldty: ty, $encoding: ident))) => {
+		$crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field.map(|f| $encoding(f)), option);
+	};
 	($len: expr, $type: expr, $field: expr, upgradable_required) => {
 		$crate::_get_varint_length_prefixed_tlv_length!($len, $type, $field, required);
 	};