/*
 * Copyright (c) 2006 Georgia Tech Research Corporation
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: George F. Riley<riley@ece.gatech.edu>
 *         Gustavo Carneiro <gjc@inescporto.pt>
 */

#ifndef IPV4_STATIC_ROUTING_H
#define IPV4_STATIC_ROUTING_H

#include "ipv4-header.h"
#include "ipv4-routing-protocol.h"
#include "ipv4.h"

#include "ns3/ipv4-address.h"
#include "ns3/ptr.h"
#include "ns3/socket.h"

#include <list>
#include <stdint.h>
#include <utility>

namespace ns3
{

class Packet;
class NetDevice;
class Ipv4Interface;
class Ipv4Address;
class Ipv4Header;
class Ipv4RoutingTableEntry;
class Ipv4MulticastRoutingTableEntry;
class Node;

/**
 * @ingroup ipv4Routing
 *
 * @brief Static routing protocol for IP version 4 stacks.
 *
 * This class provides a basic set of methods for inserting static
 * unicast and multicast routes into the Ipv4 routing system.
 * This particular protocol is designed to be inserted into an
 * Ipv4ListRouting protocol but can be used also as a standalone
 * protocol.
 *
 * The Ipv4StaticRouting class inherits from the abstract base class
 * Ipv4RoutingProtocol that defines the interface methods that a routing
 * protocol must support.
 *
 * @see Ipv4RoutingProtocol
 * @see Ipv4ListRouting
 * @see Ipv4ListRouting::AddRoutingProtocol
 */
class Ipv4StaticRouting : public Ipv4RoutingProtocol
{
  public:
    /**
     * @brief The interface Id associated with this class.
     * @return type identifier
     */
    static TypeId GetTypeId();

    Ipv4StaticRouting();
    ~Ipv4StaticRouting() override;

    Ptr<Ipv4Route> RouteOutput(Ptr<Packet> p,
                               const Ipv4Header& header,
                               Ptr<NetDevice> oif,
                               Socket::SocketErrno& sockerr) override;

    bool RouteInput(Ptr<const Packet> p,
                    const Ipv4Header& header,
                    Ptr<const NetDevice> idev,
                    const UnicastForwardCallback& ucb,
                    const MulticastForwardCallback& mcb,
                    const LocalDeliverCallback& lcb,
                    const ErrorCallback& ecb) override;

    void NotifyInterfaceUp(uint32_t interface) override;
    void NotifyInterfaceDown(uint32_t interface) override;
    void NotifyAddAddress(uint32_t interface, Ipv4InterfaceAddress address) override;
    void NotifyRemoveAddress(uint32_t interface, Ipv4InterfaceAddress address) override;
    void SetIpv4(Ptr<Ipv4> ipv4) override;
    void PrintRoutingTable(Ptr<OutputStreamWrapper> stream,
                           Time::Unit unit = Time::S) const override;

    /**
     * @brief Add a network route to the static routing table.
     *
     * @param network The Ipv4Address network for this route.
     * @param networkMask The Ipv4Mask to extract the network.
     * @param nextHop The next hop in the route to the destination network.
     * @param interface The network interface index used to send packets to the
     * destination.
     * @param metric Metric of route in case of multiple routes to same destination
     *
     * @see Ipv4Address
     */
    void AddNetworkRouteTo(Ipv4Address network,
                           Ipv4Mask networkMask,
                           Ipv4Address nextHop,
                           uint32_t interface,
                           uint32_t metric = 0);

    /**
     * @brief Add a network route to the static routing table.
     *
     * @param network The Ipv4Address network for this route.
     * @param networkMask The Ipv4Mask to extract the network.
     * @param interface The network interface index used to send packets to the
     * destination.
     * @param metric Metric of route in case of multiple routes to same destination
     *
     * @see Ipv4Address
     */
    void AddNetworkRouteTo(Ipv4Address network,
                           Ipv4Mask networkMask,
                           uint32_t interface,
                           uint32_t metric = 0);

    /**
     * @brief Add a host route to the static routing table.
     *
     * @param dest The Ipv4Address destination for this route.
     * @param nextHop The Ipv4Address of the next hop in the route.
     * @param interface The network interface index used to send packets to the
     * destination.
     * @param metric Metric of route in case of multiple routes to same destination
     *
     * @see Ipv4Address
     */
    void AddHostRouteTo(Ipv4Address dest,
                        Ipv4Address nextHop,
                        uint32_t interface,
                        uint32_t metric = 0);
    /**
     * @brief Add a host route to the static routing table.
     *
     * @param dest The Ipv4Address destination for this route.
     * @param interface The network interface index used to send packets to the
     * destination.
     * @param metric Metric of route in case of multiple routes to same destination
     *
     * @see Ipv4Address
     */
    void AddHostRouteTo(Ipv4Address dest, uint32_t interface, uint32_t metric = 0);
    /**
     * @brief Add a default route to the static routing table.
     *
     * This method tells the routing system what to do in the case where a specific
     * route to a destination is not found.  The system forwards packets to the
     * specified node in the hope that it knows better how to route the packet.
     *
     * If the default route is set, it is returned as the selected route from
     * LookupStatic irrespective of destination address if no specific route is
     * found.
     *
     * @param nextHop The Ipv4Address to send packets to in the hope that they
     * will be forwarded correctly.
     * @param interface The network interface index used to send packets.
     * @param metric Metric of route in case of multiple routes to same destination
     *
     * @see Ipv4Address
     * @see Ipv4StaticRouting::Lookup
     */
    void SetDefaultRoute(Ipv4Address nextHop, uint32_t interface, uint32_t metric = 0);

    /**
     * @brief Get the number of individual unicast routes that have been added
     * to the routing table.
     *
     * @warning The default route counts as one of the routes.
     * @return number of entries
     */
    uint32_t GetNRoutes() const;

    /**
     * @brief Get the default route with lowest metric from the static routing table.
     *
     * @return If the default route is set, a pointer to that Ipv4RoutingTableEntry is
     * returned, otherwise an empty routing table entry is returned.
     *  If multiple default routes exist, the one with lowest metric is returned.
     *
     * @see Ipv4RoutingTableEntry
     */
    Ipv4RoutingTableEntry GetDefaultRoute();

    /**
     * @brief Get a route from the static unicast routing table.
     *
     * Externally, the unicast static routing table appears simply as a table with
     * n entries.
     *
     * @param i The index (into the routing table) of the route to retrieve.
     * @return If route is set, a pointer to that Ipv4RoutingTableEntry is returned, otherwise
     * a zero pointer is returned.
     *
     * @see Ipv4RoutingTableEntry
     * @see Ipv4StaticRouting::RemoveRoute
     */
    Ipv4RoutingTableEntry GetRoute(uint32_t i) const;

    /**
     * @brief Get a metric for route from the static unicast routing table.
     *
     * @param index The index (into the routing table) of the route to retrieve.
     * @return If route is set, the metric is returned. If not, an infinity metric (0xffffffff) is
     * returned
     *
     */
    uint32_t GetMetric(uint32_t index) const;

    /**
     * @brief Remove a route from the static unicast routing table.
     *
     * Externally, the unicast static routing table appears simply as a table with
     * n entries.
     *
     * @param i The index (into the routing table) of the route to remove.
     *
     * @see Ipv4RoutingTableEntry
     * @see Ipv4StaticRouting::GetRoute
     * @see Ipv4StaticRouting::AddRoute
     */
    void RemoveRoute(uint32_t i);

    /**
     * @brief Add a multicast route to the static routing table.
     *
     * A multicast route must specify an origin IP address, a multicast group and
     * an input network interface index as conditions and provide a vector of
     * output network interface indices over which packets matching the conditions
     * are sent.
     *
     * Typically there are two main types of multicast routes:  routes used during
     * forwarding, and routes used in the originator node.
     * For forwarding, all of the conditions must be explicitly provided.
     * For originator nodes, the route is equivalent to a unicast route, and
     * must be added through `AddHostRouteTo`.
     *
     * @param origin The Ipv4Address of the origin of packets for this route.  May
     * be Ipv4Address:GetAny for open groups.
     * @param group The Ipv4Address of the multicast group or this route.
     * @param inputInterface The input network interface index over which to
     * expect packets destined for this route.
     * @param outputInterfaces A vector of network interface indexes used to specify
     * how to send packets to the destination(s).
     *
     * @see Ipv4Address
     */
    void AddMulticastRoute(Ipv4Address origin,
                           Ipv4Address group,
                           uint32_t inputInterface,
                           std::vector<uint32_t> outputInterfaces);

    /**
     * @brief Add a default multicast route to the static routing table.
     *
     * This is the multicast equivalent of the unicast version SetDefaultRoute.
     * We tell the routing system what to do in the case where a specific route
     * to a destination multicast group is not found.  The system forwards
     * packets out the specified interface in the hope that "something out there"
     * knows better how to route the packet.  This method is only used in
     * initially sending packets off of a host.  The default multicast route is
     * not consulted during forwarding -- exact routes must be specified using
     * AddMulticastRoute for that case.
     *
     * Since we're basically sending packets to some entity we think may know
     * better what to do, we don't pay attention to "subtleties" like origin
     * address, nor do we worry about forwarding out multiple  interfaces.  If the
     * default multicast route is set, it is returned as the selected route from
     * LookupStatic irrespective of origin or multicast group if another specific
     * route is not found.
     *
     * @param outputInterface The network interface index used to specify where
     * to send packets in the case of unknown routes.
     *
     * @see Ipv4Address
     */
    void SetDefaultMulticastRoute(uint32_t outputInterface);

    /**
     * @brief Get the number of individual multicast routes that have been added
     * to the routing table.
     *
     * @warning The default multicast route counts as one of the routes.
     * @return number of entries
     */
    uint32_t GetNMulticastRoutes() const;

    /**
     * @brief Get a route from the static multicast routing table.
     *
     * Externally, the multicast static routing table appears simply as a table
     * with n entries.
     *
     * @param i The index (into the routing table) of the multicast route to
     * retrieve.
     * @return If route \e i is set, a pointer to that Ipv4MulticastRoutingTableEntry is
     * returned, otherwise a zero pointer is returned.
     *
     * @see Ipv4MulticastRoutingTableEntry
     * @see Ipv4StaticRouting::RemoveRoute
     */
    Ipv4MulticastRoutingTableEntry GetMulticastRoute(uint32_t i) const;

    /**
     * @brief Remove a route from the static multicast routing table.
     *
     * Externally, the multicast static routing table appears simply as a table
     * with n entries.
     * This method causes the multicast routing table to be searched for the first
     * route that matches the parameters and removes it.
     *
     * Wildcards may be provided to this function, but the wildcards are used to
     * exactly match wildcards in the routes (see AddMulticastRoute).  That is,
     * calling RemoveMulticastRoute with the origin set to "0.0.0.0" will not
     * remove routes with any address in the origin, but will only remove routes
     * with "0.0.0.0" set as the the origin.
     *
     * @param origin The IP address specified as the origin of packets for the
     * route.
     * @param group The IP address specified as the multicast group address of
     * the route.
     * @param inputInterface The network interface index specified as the expected
     * input interface for the route.
     * @returns true if a route was found and removed, false otherwise.
     *
     * @see Ipv4MulticastRoutingTableEntry
     * @see Ipv4StaticRouting::AddMulticastRoute
     */
    bool RemoveMulticastRoute(Ipv4Address origin, Ipv4Address group, uint32_t inputInterface);

    /**
     * @brief Remove a route from the static multicast routing table.
     *
     * Externally, the multicast static routing table appears simply as a table
     * with n entries.
     *
     * @param index The index (into the multicast routing table) of the route to
     * remove.
     *
     * @see Ipv4RoutingTableEntry
     * @see Ipv4StaticRouting::GetRoute
     * @see Ipv4StaticRouting::AddRoute
     */
    void RemoveMulticastRoute(uint32_t index);

  protected:
    void DoDispose() override;

  private:
    /// Container for the network routes
    typedef std::list<std::pair<Ipv4RoutingTableEntry*, uint32_t>> NetworkRoutes;

    /// Const Iterator for container for the network routes
    typedef std::list<std::pair<Ipv4RoutingTableEntry*, uint32_t>>::const_iterator NetworkRoutesCI;

    /// Iterator for container for the network routes
    typedef std::list<std::pair<Ipv4RoutingTableEntry*, uint32_t>>::iterator NetworkRoutesI;

    /// Container for the multicast routes
    typedef std::list<Ipv4MulticastRoutingTableEntry*> MulticastRoutes;

    /// Const Iterator for container for the multicast routes
    typedef std::list<Ipv4MulticastRoutingTableEntry*>::const_iterator MulticastRoutesCI;

    /// Iterator for container for the multicast routes
    typedef std::list<Ipv4MulticastRoutingTableEntry*>::iterator MulticastRoutesI;

    /**
     * @brief Checks if a route is already present in the forwarding table.
     * @param route route
     * @param metric metric of route
     * @return true if the route/metric is already in the forwarding table
     */
    bool LookupRoute(const Ipv4RoutingTableEntry& route, uint32_t metric);

    /**
     * @brief Lookup in the forwarding table for destination.
     * @param dest destination address
     * @param oif output interface if any (put 0 otherwise)
     * @return Ipv4Route to route the packet to reach dest address
     */
    Ptr<Ipv4Route> LookupStatic(Ipv4Address dest, Ptr<NetDevice> oif = nullptr);

    /**
     * @brief Lookup in the multicast forwarding table for destination.
     * @param origin source address
     * @param group group multicast address
     * @param interface interface index
     * @return Ipv4MulticastRoute to route the packet to reach dest address
     */
    Ptr<Ipv4MulticastRoute> LookupStatic(Ipv4Address origin, Ipv4Address group, uint32_t interface);

    /**
     * @brief the forwarding table for network.
     */
    NetworkRoutes m_networkRoutes;

    /**
     * @brief the forwarding table for multicast.
     */
    MulticastRoutes m_multicastRoutes;

    /**
     * @brief Ipv4 reference.
     */
    Ptr<Ipv4> m_ipv4;
};

} // Namespace ns3

#endif /* IPV4_STATIC_ROUTING_H */
