Struct Router 

pub struct Router {
    pub if_index: u32,
    pub neighbors: HashMap<Ipv4Addr, Neighbor>,
    pub routes: PrefixMap<Ipv4Net, Ipv4Route>,
}

Manages a cached view of the system’s IPv4 routing and neighbor tables.

It holds the routing table in a prefix trie for efficient longest-prefix-match lookups and the neighbor (ARP) table in a hash map.

Fields

if_index: u32

The network interface index this router is bound to.

neighbors: HashMap<Ipv4Addr, Neighbor>

A cache of neighbor (ARP) entries, mapping IP addresses to Neighbor structs.

routes: PrefixMap<Ipv4Net, Ipv4Route>

A prefix trie (PrefixMap) for efficient longest-prefix-match lookups on routes.

Implementations

impl Router

pub fn new(if_index: u32) -> Self

Creates a new Router for a specific network interface.

Arguments

• if_index - The index of the network interface to manage routes for.

pub fn route(&mut self, dest_ip: &Ipv4Addr) -> Option<NextHop>

Finds the next-hop information for a given destination IPv4 address.

How it works

It first performs a longest-prefix-match (LPM) lookup in the cached routes table. If a route is found, it determines the next-hop IP (either the gateway or the destination itself). It then looks up the MAC address for that next-hop IP in the neighbors cache. If no route is found via LPM, it attempts a direct lookup in the neighbor cache for the destination IP. Returns a NextHop struct containing the next-hop IP and MAC address if successful.

pub fn refresh(&mut self) -> Result<(), Error>

Refreshes the router’s cached tables from the kernel.

How it works

It calls get_ipv4_routes and get_neighbors from the netlink module to fetch the latest data from the kernel for the router’s interface. It then rebuilds the internal routes prefix map and neighbors hash map with the new data.

Trait Implementations

impl Debug for Router

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.