f Add test coverage for less-than 76 bytes OP_PUSHDATA1 scripts

Author: tnull

lightning/src/ln/script.rs

@@ -317,16 +317,29 @@ mod shutdown_script_tests {
 		assert_eq!(shutdown_script.into_inner(), op_return_script);
 		assert!(ShutdownScript::try_from(op_return_script).is_ok());
 
-		let mut pushdata_vec = Builder::new()
-			.push_opcode(opcodes::all::OP_RETURN)
-			.push_opcode(opcodes::all::OP_PUSHDATA1)
-			.into_bytes();
-		pushdata_vec.push(80);
-		pushdata_vec.extend_from_slice(&[1u8; 80]);
-		let pushdata_script = ScriptBuf::from_bytes(pushdata_vec);
-		let pushdata_shutdown_script = ShutdownScript::try_from(pushdata_script).unwrap();
-		assert!(pushdata_shutdown_script.is_compatible(&simple_close_features()));
-		assert!(!pushdata_shutdown_script.is_compatible(&InitFeatures::empty()));
+		let assert_pushdata_script_compat = |len| {
+			let mut pushdata_vec = Builder::new()
+				.push_opcode(opcodes::all::OP_RETURN)
+				.push_opcode(opcodes::all::OP_PUSHDATA1)
+				.into_bytes();
+			pushdata_vec.push(len as u8);
+			pushdata_vec.extend_from_slice(&vec![1u8; len]);
+			let pushdata_script = ScriptBuf::from_bytes(pushdata_vec);
+			let pushdata_shutdown_script = ShutdownScript::try_from(pushdata_script).unwrap();
+			assert!(pushdata_shutdown_script.is_compatible(&simple_close_features()));
+			assert!(!pushdata_shutdown_script.is_compatible(&InitFeatures::empty()));
+		};
+
+		// For `option_simple_close` we assert compatibility with `OP_PUSHDATA1` scripts for the
+		// intended length range of 76 to 80 bytes.
+		assert_pushdata_script_compat(76);
+		assert_pushdata_script_compat(80);
+
+		// While the `option_simple_close` spec prescribes the use of `OP_PUSHBYTES_0` up to 75
+		// bytes, we follow Postel's law and accept if our counterparty would create an
+		// `OP_PUSHDATA1` script for less than 76 bytes of payload.
+		assert_pushdata_script_compat(75);
+		assert_pushdata_script_compat(6);
 	}
 
 	#[test]