/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright (c) 2016-2017, Chris Fraire <cfraire@me.com>.
 *
 * INIT_REBOOT state of the DHCP client state machine.
 */

#include <sys/types.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/dhcp.h>
#include <netinet/udp.h>
#include <netinet/ip_var.h>
#include <netinet/udp_var.h>
#include <dhcpmsg.h>
#include <string.h>

#include "agent.h"
#include "packet.h"
#include "states.h"
#include "util.h"
#include "interface.h"
#include "defaults.h"

static stop_func_t      stop_init_reboot;

/*
 * dhcp_init_reboot_v4(): attempts to reuse a cached configuration for a state
 *                        machine.
 *
 *   input: dhcp_smach_t *: the state machine to examine for reuse
 *  output: void
 */

static void
dhcp_init_reboot_v4(dhcp_smach_t *dsmp)
{
        dhcp_pkt_t              *dpkt;

        /*
         * assemble DHCPREQUEST message.  The max dhcp message size
         * option is set to the interface max, minus the size of the udp and
         * ip headers.
         */

        dpkt = init_pkt(dsmp, REQUEST);
        (void) add_pkt_opt32(dpkt, CD_REQUESTED_IP_ADDR,
            dsmp->dsm_ack->pkt->yiaddr.s_addr);

        (void) add_pkt_opt32(dpkt, CD_LEASE_TIME, htonl(DHCP_PERM));
        (void) add_pkt_opt16(dpkt, CD_MAX_DHCP_SIZE,
            htons(dsmp->dsm_lif->lif_pif->pif_mtu - sizeof (struct udpiphdr)));

        if (class_id_len != 0)
                (void) add_pkt_opt(dpkt, CD_CLASS_ID, class_id, class_id_len);
        (void) add_pkt_prl(dpkt, dsmp);

        if (!dhcp_add_fqdn_opt(dpkt, dsmp))
                (void) dhcp_add_hostname_opt(dpkt, dsmp);

        (void) add_pkt_opt(dpkt, CD_END, NULL, 0);

        (void) send_pkt(dsmp, dpkt, htonl(INADDR_BROADCAST), stop_init_reboot);
}


/*
 * dhcp_init_reboot_v6(): attempts to reuse a cached configuration for a state
 *                        machine.  Create a Confirm message and multicast it
 *                        out.
 *
 *   input: dhcp_smach_t *: the state machine to examine for reuse
 *  output: void
 */

static void
dhcp_init_reboot_v6(dhcp_smach_t *dsmp)
{
        dhcp_pkt_t *dpkt;
        dhcpv6_option_t *d6o, *d6so, *popt;
        uint_t olen, solen;
        dhcpv6_ia_na_t d6in;
        dhcpv6_iaaddr_t d6ia;
        char *obase;

        /*
         * Assemble a Confirm message based on the current ack.
         */

        dpkt = init_pkt(dsmp, DHCPV6_MSG_CONFIRM);

        /*
         * Loop over and copy IA_NAs and IAADDRs we have in our last ack.  This
         * is what we'll be requesting.
         */
        d6o = NULL;
        while ((d6o = dhcpv6_pkt_option(dsmp->dsm_ack, d6o, DHCPV6_OPT_IA_NA,
            &olen)) != NULL) {

                /*
                 * Copy in IA_NA option from the ack.  Note that we use zero
                 * for all timers in accordance with RFC 3315.  (It would make
                 * some sense to say what we think the current timers are as
                 * a hint to the server, but the RFC doesn't agree.)
                 */
                if (olen < sizeof (dhcpv6_ia_na_t))
                        continue;
                (void) memcpy(&d6in, d6o, sizeof (d6in));
                d6in.d6in_t1 = 0;
                d6in.d6in_t2 = 0;
                popt = add_pkt_opt(dpkt, DHCPV6_OPT_IA_NA,
                    (char *)&d6in + sizeof (*d6o),
                    sizeof (d6in) - sizeof (*d6o));
                if (popt == NULL)
                        goto failure;

                /*
                 * Now loop over the IAADDR suboptions and add those.
                 */
                obase = (char *)d6o + sizeof (dhcpv6_ia_na_t);
                olen -= sizeof (dhcpv6_ia_na_t);
                d6so = NULL;
                while ((d6so = dhcpv6_find_option(obase, olen, d6so,
                    DHCPV6_OPT_IAADDR, &solen)) != NULL) {
                        if (solen < sizeof (dhcpv6_iaaddr_t))
                                continue;
                        (void) memcpy(&d6ia, d6so, sizeof (d6ia));
                        d6ia.d6ia_preflife = 0;
                        d6ia.d6ia_vallife = 0;
                        if (add_pkt_subopt(dpkt, popt, DHCPV6_OPT_IAADDR,
                            (char *)&d6ia + sizeof (*d6so),
                            sizeof (d6ia) - sizeof (*d6so)) == NULL)
                                goto failure;
                }
        }

        /* Add required Option Request option */
        (void) add_pkt_prl(dpkt, dsmp);

        (void) send_pkt_v6(dsmp, dpkt, ipv6_all_dhcp_relay_and_servers,
            stop_init_reboot, DHCPV6_CNF_TIMEOUT, DHCPV6_CNF_MAX_RT);

        return;

failure:
        if (!set_start_timer(dsmp))
                dhcp_selecting(dsmp);
}

/*
 * dhcp_init_reboot(): attempts to reuse a cached configuration for a state
 *                     machine.
 *
 *   input: dhcp_smach_t *: the state machine to examine for reuse
 *  output: void
 */

void
dhcp_init_reboot(dhcp_smach_t *dsmp)
{
        dhcpmsg(MSG_VERBOSE,  "%s has cached configuration - entering "
            "INIT_REBOOT", dsmp->dsm_name);

        if (!set_smach_state(dsmp, INIT_REBOOT)) {
                dhcpmsg(MSG_ERROR, "dhcp_init_reboot: cannot register to "
                    "collect ACK/NAK packets, reverting to INIT on %s",
                    dsmp->dsm_name);

                dsmp->dsm_dflags |= DHCP_IF_FAILED;
                (void) set_smach_state(dsmp, INIT);
                ipc_action_finish(dsmp, DHCP_IPC_E_MEMORY);
                return;
        }

        if (dsmp->dsm_isv6)
                dhcp_init_reboot_v6(dsmp);
        else
                dhcp_init_reboot_v4(dsmp);
}

/*
 * stop_init_reboot(): decides when to stop retransmitting REQUESTs
 *
 *   input: dhcp_smach_t *: the state machine sending the REQUESTs
 *          unsigned int: the number of REQUESTs sent so far
 *  output: boolean_t: B_TRUE if retransmissions should stop
 */

static boolean_t
stop_init_reboot(dhcp_smach_t *dsmp, unsigned int n_requests)
{
        if (dsmp->dsm_isv6) {
                uint_t nowabs, maxabs;

                nowabs = NSEC2MSEC(gethrtime());
                maxabs = NSEC2MSEC(dsmp->dsm_neg_hrtime) + DHCPV6_CNF_MAX_RD;
                if (nowabs < maxabs) {
                        /* Cap the timer based on the maximum */
                        if (nowabs + dsmp->dsm_send_timeout > maxabs)
                                dsmp->dsm_send_timeout = maxabs - nowabs;
                        return (B_FALSE);
                }
        } else {
                if (n_requests < DHCP_MAX_REQUESTS)
                        return (B_FALSE);
        }

        if (df_get_bool(dsmp->dsm_name, dsmp->dsm_isv6,
            DF_VERIFIED_LEASE_ONLY)) {
                dhcpmsg(MSG_INFO,
                    "unable to verify existing lease on %s; restarting",
                    dsmp->dsm_name);
                dhcp_selecting(dsmp);
                return (B_TRUE);
        }

        if (dsmp->dsm_isv6) {
                dhcpmsg(MSG_INFO, "no Reply to Confirm, using remainder of "
                    "existing lease on %s", dsmp->dsm_name);
        } else {
                dhcpmsg(MSG_INFO, "no ACK/NAK to INIT_REBOOT REQUEST, "
                    "using remainder of existing lease on %s", dsmp->dsm_name);
        }

        /*
         * We already stuck our old ack in dsmp->dsm_ack and relativized the
         * packet times, so we can just pretend that the server sent it to us
         * and move to bound.  If that fails, fall back to selecting.
         */

        if (dhcp_bound(dsmp, NULL)) {
                if (dsmp->dsm_isv6) {
                        if (!save_server_id(dsmp, dsmp->dsm_ack))
                                goto failure;
                        server_unicast_option(dsmp, dsmp->dsm_ack);
                }
        } else {
failure:
                dhcpmsg(MSG_INFO, "unable to use saved lease on %s; restarting",
                    dsmp->dsm_name);
                dhcp_selecting(dsmp);
        }

        return (B_TRUE);
}