f - Restrict timestamps to 35 bits

Author: jkczyz

lightning-invoice/src/lib.rs

@@ -85,12 +85,15 @@ mod sync;
 
 pub use de::{ParseError, ParseOrSemanticError};
 
+/// The number of bits used to represent timestamps as defined in BOLT 11.
+const TIMESTAMP_BITS: usize = 35;
+
 /// The maximum timestamp that can be represented as a [`Duration`] since the UNIX epoch while
 /// allowing for adding an expiry without overflowing.
-const MAX_TIMESTAMP: u64 = core::i64::MAX as u64;
+const MAX_TIMESTAMP: u64 = core::u64::MAX >> (64 - TIMESTAMP_BITS);
 
 /// The maximum expiry allowed, represented as a [`Duration`] since the invoice timestamp.
-const MAX_EXPIRY_TIME: u64 = (core::i64::MAX) as u64 + 1;
+const MAX_EXPIRY_TIME: u64 = core::u64::MAX - MAX_TIMESTAMP;
 
 /// Assert that the maximum expiry represented as a [`Duration`] since the UNIX epoch does not
 /// exceed [`u64::MAX`].