Allow masking IPv4/6 and HW addresses

src/ipv6_address.cpp

@@ -132,4 +132,13 @@ bool IPv6Address::is_multicast() const {
     return multicast_range.contains(*this);
 }
 
+IPv6Address operator&(const IPv6Address& lhs, const IPv6Address& rhs) {
+    IPv6Address output = lhs;
+    IPv6Address::iterator addr_iter = output.begin();
+    for (IPv6Address::const_iterator it = rhs.begin(); it != rhs.end(); ++it, ++addr_iter) {
+        *addr_iter = *addr_iter & *it;
+    }
+    return output;
+}
+
 } // Tins