fix: correct matches_requested_range for suffix ranges

With suffix clamping, a non-zero suffix is always satisfiable
regardless of file size. The only unsatisfiable suffix is `Suffix(0)`.

Previously `Suffix(0)` against `Unsatisfiable` incorrectly returned
`false` because `0 > size` is never true.

Author: mi-caren

src/headers/content_range.rs

@@ -44,10 +44,9 @@ impl HttpContentRange {
                 HttpRange::Range(OrderedRange { end: n, .. }),
                 HttpContentRange::Unsatisfiable(Unsatisfiable { size }),
             ) => n >= *size,
-            (
-                HttpRange::Suffix(suffix),
-                HttpContentRange::Unsatisfiable(Unsatisfiable { size }),
-            ) => suffix > *size,
+            (HttpRange::Suffix(suffix), HttpContentRange::Unsatisfiable(Unsatisfiable { .. })) => {
+                suffix == 0
+            }
         }
     }
 }

src/headers/tests.rs

@@ -146,12 +146,20 @@ mod content_range {
         }
 
         #[test]
-        fn unsuccessful_range_suffix_range_content_bound() {
-            let range = HttpRange::Suffix(50);
+        fn unsuccessful_range_suffix_zero_content_unsatisfiable() {
+            let range = HttpRange::Suffix(0);
             let content_range = HttpContentRange::Unsatisfiable(Unsatisfiable::new(20));
 
             assert!(content_range.matches_requested_range(range));
         }
+
+        #[test]
+        fn suffix_exceeding_size_is_not_unsatisfiable() {
+            let range = HttpRange::Suffix(50);
+            let content_range = HttpContentRange::Unsatisfiable(Unsatisfiable::new(20));
+
+            assert!(!content_range.matches_requested_range(range));
+        }
     }
 }
 

src/lib.rs

@@ -55,7 +55,9 @@ pub fn file_range(
 
     let range = match http_range {
         HttpRange::StartingPoint(start) if start < size => start..=size - 1,
-        HttpRange::Range(range) if range.start() < size => range.start()..=range.end().min(size - 1),
+        HttpRange::Range(range) if range.start() < size => {
+            range.start()..=range.end().min(size - 1)
+        }
         HttpRange::Suffix(suffix) if suffix > 0 => size.saturating_sub(suffix)..=size - 1,
         _ => {
             let content_range = HttpContentRange::Unsatisfiable(Unsatisfiable::new(size));