Merge pull request lightningdevkit#3506 from tnull/2025-01-allow-upperase-hrp-main

Allow uppercase bech32 HRP (main)

Author: tnull

lightning/src/offers/parse.rs

@@ -58,7 +58,8 @@ mod sealed {
 
 			let parsed = CheckedHrpstring::new::<NoChecksum>(encoded.as_ref())?;
 			let hrp = parsed.hrp();
-			if hrp.as_str() != Self::BECH32_HRP {
+			// Compare the lowercase'd iter to allow for all-uppercase HRPs
+			if hrp.lowercase_char_iter().ne(Self::BECH32_HRP.chars()) {
 				return Err(Bolt12ParseError::InvalidBech32Hrp);
 			}
 
@@ -233,6 +234,7 @@ impl From<secp256k1::Error> for Bolt12ParseError {
 mod bolt12_tests {
 	use super::Bolt12ParseError;
 	use crate::offers::offer::Offer;
+	use bech32::primitives::decode::{CheckedHrpstringError, UncheckedHrpstringError, CharError};
 
 	#[test]
 	fn encodes_offer_as_bech32_without_checksum() {
@@ -249,6 +251,9 @@ mod bolt12_tests {
 			// A complete string is valid
 			"lno1pqps7sjqpgtyzm3qv4uxzmtsd3jjqer9wd3hy6tsw35k7msjzfpy7nz5yqcnygrfdej82um5wf5k2uckyypwa3eyt44h6txtxquqh7lz5djge4afgfjn7k4rgrkuag0jsd5xvxg",
 
+			// Uppercase is valid
+			"LNO1PQPS7SJQPGTYZM3QV4UXZMTSD3JJQER9WD3HY6TSW35K7MSJZFPY7NZ5YQCNYGRFDEJ82UM5WF5K2UCKYYPWA3EYT44H6TXTXQUQH7LZ5DJGE4AFGFJN7K4RGRKUAG0JSD5XVXG",
+
 			// + can join anywhere
 			"l+no1pqps7sjqpgtyzm3qv4uxzmtsd3jjqer9wd3hy6tsw35k7msjzfpy7nz5yqcnygrfdej82um5wf5k2uckyypwa3eyt44h6txtxquqh7lz5djge4afgfjn7k4rgrkuag0jsd5xvxg",
 
@@ -282,6 +287,16 @@ mod bolt12_tests {
 			}
 		}
 	}
+
+	#[test]
+	fn fails_parsing_bech32_encoded_offers_with_mixed_casing() {
+		// We assert that mixed-case encoding fails to parse.
+		let mixed_case_offer = "LnO1PqPs7sJqPgTyZm3qV4UxZmTsD3JjQeR9Wd3hY6TsW35k7mSjZfPy7nZ5YqCnYgRfDeJ82uM5Wf5k2uCkYyPwA3EyT44h6tXtXqUqH7Lz5dJgE4AfGfJn7k4rGrKuAg0jSd5xVxG";
+		match mixed_case_offer.parse::<Offer>() {
+			Ok(_) => panic!("Valid offer: {}", mixed_case_offer),
+			Err(e) => assert_eq!(e, Bolt12ParseError::Bech32(CheckedHrpstringError::Parse(UncheckedHrpstringError::Char(CharError::MixedCase)))),
+		}
+	}
 }
 
 #[cfg(test)]