// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * EIGRP Sending and Receiving EIGRP SIA-Reply Packets.
 * Copyright (C) 2013-2014
 * Authors:
 *   Donnie Savage
 *   Jan Janovic
 *   Matej Perina
 *   Peter Orsag
 *   Peter Paluch
 */
#include <zebra.h>

#include "frrevent.h"
#include "memory.h"
#include "linklist.h"
#include "prefix.h"
#include "if.h"
#include "table.h"
#include "sockunion.h"
#include "stream.h"
#include "log.h"
#include "sockopt.h"
#include "checksum.h"
#include "md5.h"
#include "vty.h"

#include "eigrpd/eigrp_structs.h"
#include "eigrpd/eigrpd.h"
#include "eigrpd/eigrp_interface.h"
#include "eigrpd/eigrp_neighbor.h"
#include "eigrpd/eigrp_packet.h"
#include "eigrpd/eigrp_zebra.h"
#include "eigrpd/eigrp_vty.h"
#include "eigrpd/eigrp_dump.h"
#include "eigrpd/eigrp_macros.h"
#include "eigrpd/eigrp_topology.h"
#include "eigrpd/eigrp_fsm.h"

/*EIGRP SIA-REPLY read function*/
void eigrp_siareply_receive(struct eigrp *eigrp, struct ip *iph,
			    struct eigrp_header *eigrph, struct stream *s,
			    struct eigrp_interface *ei, int size)
{
	struct eigrp_neighbor *nbr;
	struct TLV_IPv4_Internal_type *tlv;

	uint16_t type;

	/* increment statistics. */
	ei->siaReply_in++;

	/* get neighbor struct */
	nbr = eigrp_nbr_get(ei, eigrph, iph);

	/* neighbor must be valid, eigrp_nbr_get creates if none existed */
	assert(nbr);

	nbr->recv_sequence_number = ntohl(eigrph->sequence);

	while (s->endp > s->getp) {
		type = stream_getw(s);
		if (type == EIGRP_TLV_IPv4_INT) {
			struct prefix dest_addr;

			stream_set_getp(s, s->getp - sizeof(uint16_t));

			tlv = eigrp_read_ipv4_tlv(s);

			dest_addr.family = AFI_IP;
			dest_addr.u.prefix4 = tlv->destination;
			dest_addr.prefixlen = tlv->prefix_length;
			struct eigrp_prefix_descriptor *dest =
				eigrp_topology_table_lookup_ipv4(
					eigrp->topology_table, &dest_addr);

			/* If the destination exists (it should, but one never
			 * know)*/
			if (dest != NULL) {
				struct eigrp_fsm_action_message msg;
				struct eigrp_route_descriptor *entry =
					eigrp_route_descriptor_lookup(
						dest->entries, nbr);
				msg.packet_type = EIGRP_OPC_SIAQUERY;
				msg.eigrp = eigrp;
				msg.data_type = EIGRP_INT;
				msg.adv_router = nbr;
				msg.metrics = tlv->metric;
				msg.entry = entry;
				msg.prefix = dest;
				eigrp_fsm_event(&msg);
			}
			eigrp_IPv4_InternalTLV_free(tlv);
		}
	}
	eigrp_hello_send_ack(nbr);
}

void eigrp_send_siareply(struct eigrp_neighbor *nbr,
			 struct eigrp_prefix_descriptor *pe)
{
	struct eigrp_packet *ep;
	uint16_t length = EIGRP_HEADER_LEN;

	ep = eigrp_packet_new(EIGRP_PACKET_MTU(nbr->ei->ifp->mtu), nbr);

	/* Prepare EIGRP INIT UPDATE header */
	eigrp_packet_header_init(EIGRP_OPC_SIAREPLY, nbr->ei->eigrp, ep->s, 0,
				 nbr->ei->eigrp->sequence_number, 0);

	// encode Authentication TLV, if needed
	if (nbr->ei->params.auth_type == EIGRP_AUTH_TYPE_MD5
	    && nbr->ei->params.auth_keychain != NULL) {
		length += eigrp_add_authTLV_MD5_to_stream(ep->s, nbr->ei);
	}

	length += eigrp_add_internalTLV_to_stream(ep->s, pe);

	if ((nbr->ei->params.auth_type == EIGRP_AUTH_TYPE_MD5)
	    && (nbr->ei->params.auth_keychain != NULL)) {
		eigrp_make_md5_digest(nbr->ei, ep->s, EIGRP_AUTH_UPDATE_FLAG);
	}

	/* EIGRP Checksum */
	eigrp_packet_checksum(nbr->ei, ep->s, length);

	ep->length = length;
	ep->dst.s_addr = nbr->src.s_addr;

	/*This ack number we await from neighbor*/
	ep->sequence_number = nbr->ei->eigrp->sequence_number;

	if (nbr->state == EIGRP_NEIGHBOR_UP) {
		/*Put packet to retransmission queue*/
		eigrp_fifo_push(nbr->retrans_queue, ep);

		if (nbr->retrans_queue->count == 1) {
			eigrp_send_packet_reliably(nbr);
		}
	} else
		eigrp_packet_free(ep);
}
