/*      $OpenBSD: reply.c,v 1.5 2016/09/02 16:46:29 renato Exp $ */

/*
 * Copyright (c) 2015 Renato Westphal <renato@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>

#include <stdlib.h>

#include "eigrpd.h"
#include "eigrpe.h"
#include "log.h"

/* reply packet handling */

void
send_reply(struct nbr *nbr, struct rinfo_head *rinfo_list, int siareply)
{
        struct eigrp            *eigrp = nbr->ei->eigrp;
        struct ibuf             *buf;
        uint16_t                 opcode;
        struct rinfo_entry      *re;
        int                      size;
        int                      route_len;

        if (rinfo_list == NULL || TAILQ_EMPTY(rinfo_list))
                return;

        do {
                if ((buf = ibuf_dynamic(PKG_DEF_SIZE,
                    IP_MAXPACKET - sizeof(struct ip))) == NULL)
                        fatal("send_reply");

                if (!siareply)
                         opcode = EIGRP_OPC_REPLY;
                else
                         opcode = EIGRP_OPC_SIAREPLY;

                /* EIGRP header */
                if (gen_eigrp_hdr(buf, opcode, 0, eigrp->seq_num, eigrp->as))
                        goto fail;

                switch (eigrp->af) {
                case AF_INET:
                        size = sizeof(struct ip);
                        break;
                case AF_INET6:
                        size = sizeof(struct ip6_hdr);
                        break;
                default:
                        fatalx("send_reply: unknown af");
                }
                size += sizeof(struct eigrp_hdr);

                while ((re = TAILQ_FIRST(rinfo_list)) != NULL) {
                        route_len = len_route_tlv(&re->rinfo);
                        /* don't exceed the MTU to avoid IP fragmentation */
                        if (size + route_len > nbr->ei->iface->mtu) {
                                rtp_send_ucast(nbr, buf);
                                break;
                        }
                        size += route_len;

                        if (gen_route_tlv(buf, &re->rinfo))
                                goto fail;
                        TAILQ_REMOVE(rinfo_list, re, entry);
                        free(re);
                }
        } while (!TAILQ_EMPTY(rinfo_list));

        /* reply packets are always unicast */
        rtp_send_ucast(nbr, buf);
        return;
fail:
        log_warnx("%s: failed to send message", __func__);
        if (rinfo_list)
                message_list_clr(rinfo_list);
        ibuf_free(buf);
        return;
}

void
recv_reply(struct nbr *nbr, struct rinfo_head *rinfo_list, int siareply)
{
        int                      type;
        struct rinfo_entry      *re;

        /*
         * draft-savage-eigrp-02 - Section 4.3:
         * "When a REPLY packet is received, there is no reason to process
         * the packet before an acknowledgment is sent. Therefore, an Ack
         * packet is sent immediately and then the packet is processed."
         */
        rtp_send_ack(nbr);

        if (!siareply)
                type = IMSG_RECV_REPLY;
        else
                type = IMSG_RECV_SIAREPLY;

        TAILQ_FOREACH(re, rinfo_list, entry)
                eigrpe_imsg_compose_rde(type, nbr->peerid, 0, &re->rinfo,
                    sizeof(re->rinfo));
}