Merge pull request #3 from LayerZero-Labs/fix/refill-method-overflow

Fix potential overflow in `refill` method

packages/solana/contracts/programs/oft/src/state/peer.rs

@@ -35,7 +35,8 @@ impl RateLimiter {
         let current_time: u64 = Clock::get()?.unix_timestamp.try_into().unwrap();
         if current_time > self.last_refill_time {
             let time_elapsed_in_seconds = current_time - self.last_refill_time;
-            new_tokens += time_elapsed_in_seconds * self.refill_per_second;
+            new_tokens = new_tokens
+                .saturating_add(time_elapsed_in_seconds.saturating_mul(self.refill_per_second));
         }
         self.tokens = std::cmp::min(self.capacity, self.tokens.saturating_add(new_tokens));
 
@@ -49,7 +50,7 @@ impl RateLimiter {
             Some(new_tokens) => {
                 self.tokens = new_tokens;
                 Ok(())
-            },
+            }
             None => Err(error!(OftError::RateLimitExceeded)),
         }
     }