From 482ed4921cdc5edb51144aa948e67c1462c2e6e9 Mon Sep 17 00:00:00 2001
From: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Date: Thu, 3 Apr 2025 16:37:08 +0200
Subject: [PATCH] invoice: reproduce parsing mismatch

This is a reproduction of the issue that I found in the
lightning-invoice crate. The issue is described in details
in [1].

[1] https://github.com/lightningdevkit/rust-lightning/issues/3693
Suggested-by: @erickcestari
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
---
 lightning-invoice/.DS_Store  | Bin 0 -> 6148 bytes
 lightning-invoice/src/de.rs  |  28 ++++++++++++++++++++++++++++
 lightning-invoice/src/lib.rs |   4 ++--
 3 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 lightning-invoice/.DS_Store

diff --git a/lightning-invoice/.DS_Store b/lightning-invoice/.DS_Store
new file mode 100644
index 0000000000000000000000000000000000000000..7120522d1247b54c4b7d572be8a7b43600f0f969
GIT binary patch
literal 6148
zcmeHKy-or_5S|fCF0rAc+|F3?1}iyUKwf|VMhY%R1Pi+>>3kVlTPs^%#oBLn2DyzF
zOJj5<+5KkcXJ_vt><<y~_+dFB8W2%|Cdi_6h?qNFXBI3@mN`b#MO|%@_2{#ZUkkGK
z9&PEK7VEqA`Y*3eo~ka(`MRFNQaruI*J}TA-S#fO@orY_S!YP2bK21@YVK&8)uh#X
z?rql{J|AulkEw1ezp78QyCbstq(6=<!o?YI2AlzB;NLQUGh3v%Q1spza0Z-#PX=Uv
z2xx-Quu)7~2fB342lio30$tt`k`oN0VWS8Sgf$hYsccUS)^yl|#YMwLQPYX-fx%Y!
z_;}$|9rK42P8=1zcLtn+oPnMW2Xg*T@R#X)<mV|qat54%KgIy}%V{~rN7>o><@4mM
v4QMko5s7O=fk4kL0T{?WGE7eO2hkB14I4$7MeHdZ=of)Rh<DDw4>0fnT;@in

literal 0
HcmV?d00001

diff --git a/lightning-invoice/src/de.rs b/lightning-invoice/src/de.rs
index 85a0924ce22..d038296c71c 100644
--- a/lightning-invoice/src/de.rs
+++ b/lightning-invoice/src/de.rs
@@ -1416,4 +1416,32 @@ mod test {
 		assert!(parse_is_code_length_err(&too_long));
 		assert!(!parse_is_code_length_err(&too_long[..too_long.len() - 1]));
 	}
+
+	#[test]
+	fn test_raw_data_base32_roundtrip() {
+		use crate::ser::Base32Iterable;
+		use crate::RawDataPart;
+		use bech32::Fe32;
+
+		// These are the expected Fe32 values that should round-trip correctly
+		// The critical difference is in the handling of tag 5 (Features) with empty payload
+		let expected_values: Vec<u8> = vec![
+			0, 0, 4, 8, 23, 5, 0, 1, 1, 20, 16, 0, 24, 0, 1, 18, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+			0, 0, 0, 0, 24, 0, 1, 18, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0,
+			0, 16, 0, 0, 0, 0, 0, 5, 0, 1, 0, 13, 0, 0,
+		];
+
+		// Convert to Fe32 for processing
+		let values_input: Vec<Fe32> = expected_values
+			.iter()
+			.map(|&v| <Fe32 as TryFrom<u8>>::try_from(v).expect("Value out of range"))
+			.collect();
+
+		// Round-trip through the parser
+		let raw_data = RawDataPart::from_base32(&values_input).unwrap();
+		let actual_output = raw_data.fe_iter().collect::<Vec<_>>();
+
+		// The test fails because the parser doesn't correctly handle empty Features field
+		assert_eq!(values_input, actual_output, "Failed to correctly round-trip BOLT11 data");
+	}
 }
diff --git a/lightning-invoice/src/lib.rs b/lightning-invoice/src/lib.rs
index b814210b390..ddda765e8f6 100644
--- a/lightning-invoice/src/lib.rs
+++ b/lightning-invoice/src/lib.rs
@@ -77,9 +77,9 @@ mod prelude {
 use crate::prelude::*;
 
 /// Re-export serialization traits
-#[cfg(fuzzing)]
+#[cfg(any(fuzzing, test))]
 pub use crate::de::FromBase32;
-#[cfg(not(fuzzing))]
+#[cfg(not(any(fuzzing, test)))]
 use crate::de::FromBase32;
 #[cfg(fuzzing)]
 pub use crate::ser::Base32Iterable;