rtnetlink: Migrate neighbor functions

Change-Id: I697f3d70f327f5d1d5e104dc7e4a2af528bf2b6e
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/types.hpp b/src/types.hpp
index 8755068..bdb431d 100644
--- a/src/types.hpp
+++ b/src/types.hpp
@@ -86,6 +86,17 @@
     uint32_t flags;
 };
 
+/** @class NeighborInfo
+ *  @brief Information about a neighbor from the kernel
+ */
+struct NeighborInfo
+{
+    unsigned ifidx;
+    InAddrAny addr;
+    std::optional<ether_addr> mac;
+    uint16_t state;
+};
+
 struct string_hash : public std::hash<std::string_view>
 {
     using is_transparent = void;