fix for 0.0.0.0/0 network (#199)

src/ipv4.rs

@@ -166,7 +166,9 @@ impl Ipv4Network {
     /// ```
     pub fn mask(&self) -> Ipv4Addr {
         debug_assert!(self.prefix <= 32);
-
+        if self.prefix == 0 {
+            return Ipv4Addr::new(0, 0, 0, 0);
+        }
         let mask = u32::MAX << (IPV4_BITS - self.prefix);
         Ipv4Addr::from(mask)
     }
@@ -244,6 +246,9 @@ impl Ipv4Network {
     /// ```
     pub fn size(self) -> u32 {
         debug_assert!(self.prefix <= 32);
+        if self.prefix == 0 {
+            return u32::MAX;
+        }
         1 << (IPV4_BITS - self.prefix)
     }
 

tests/test_json.rs

@@ -82,4 +82,12 @@ mod tests {
             panic!("{}", s);
         }
     }
+
+
+    #[test]
+    fn test_ipnetwork_size_with_prefix_0() {
+        let network: Ipv4Network = "0.0.0.0/0".parse().unwrap();
+        let size = network.size();
+        assert_eq!(size, u32::MAX);
+    }
 }