/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright (C) 2014 Intel Corporation. All rights reserved.

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <netinet/ether.h>
#include <linux/if.h>

#include "networkd-link.h"
#include "network-internal.h"

#include "sd-ndisc.h"
#include "sd-dhcp6-client.h"

static int dhcp6_lease_address_acquired(sd_dhcp6_client *client, Link *link);

static int dhcp6_lease_information_acquired(sd_dhcp6_client *client,
                                        Link *link) {
        return 0;
}

static int dhcp6_address_handler(sd_netlink *rtnl, sd_netlink_message *m,
                                 void *userdata) {
        _cleanup_link_unref_ Link *link = userdata;
        int r;

        assert(link);

        r = sd_netlink_message_get_errno(m);
        if (r < 0 && r != -EEXIST) {
                if (link->rtnl_extended_attrs) {
                        log_link_warning(link, "Could not set extended netlink attributes, reverting to fallback mechanism");

                        link->rtnl_extended_attrs = false;
                        dhcp6_lease_address_acquired(link->dhcp6_client, link);

                        return 1;
                }

                log_link_error_errno(link, r, "Could not set DHCPv6 address: %m");

                link_enter_failed(link);

        } else if (r >= 0)
                manager_rtnl_process_address(rtnl, m, link->manager);

        return 1;
}

static int dhcp6_address_change(Link *link, struct in6_addr *ip6_addr,
                                uint8_t prefixlen, uint32_t lifetime_preferred,
                                uint32_t lifetime_valid) {
        int r;
        _cleanup_address_free_ Address *addr = NULL;

        r = address_new(&addr);
        if (r < 0)
                return r;

        addr->family = AF_INET6;
        memcpy(&addr->in_addr.in6, ip6_addr, sizeof(*ip6_addr));

        addr->flags = IFA_F_NOPREFIXROUTE;
        addr->prefixlen = prefixlen;

        addr->cinfo.ifa_prefered = lifetime_preferred;
        addr->cinfo.ifa_valid = lifetime_valid;

        log_link_info(link,
                      "DHCPv6 address "SD_NDISC_ADDRESS_FORMAT_STR"/%d timeout preferred %d valid %d",
                      SD_NDISC_ADDRESS_FORMAT_VAL(addr->in_addr.in6),
                      addr->prefixlen, lifetime_preferred, lifetime_valid);

        r = address_configure(addr, link, dhcp6_address_handler, true);
        if (r < 0)
                log_link_warning_errno(link, r, "Could not assign DHCPv6 address: %m");

        return r;
}

static int dhcp6_lease_address_acquired(sd_dhcp6_client *client, Link *link) {
        int r;
        sd_dhcp6_lease *lease;
        struct in6_addr ip6_addr;
        uint32_t lifetime_preferred, lifetime_valid;
        uint8_t prefixlen;

        r = sd_dhcp6_client_get_lease(client, &lease);
        if (r < 0)
                return r;

        sd_dhcp6_lease_reset_address_iter(lease);

        while (sd_dhcp6_lease_get_address(lease, &ip6_addr,
                                                &lifetime_preferred,
                                                &lifetime_valid) >= 0) {

                r = sd_ndisc_get_prefixlen(link->ndisc_router_discovery,
                                        &ip6_addr, &prefixlen);
                if (r < 0 && r != -EADDRNOTAVAIL) {
                        log_link_warning_errno(link, r, "Could not get prefix information: %m");
                        return r;
                }

                if (r == -EADDRNOTAVAIL)
                        prefixlen = 128;

                r = dhcp6_address_change(link, &ip6_addr, prefixlen,
                                        lifetime_preferred, lifetime_valid);
                if (r < 0)
                        return r;
        }

        return 0;
}

static void dhcp6_handler(sd_dhcp6_client *client, int event, void *userdata) {
        int r;
        Link *link = userdata;

        assert(link);
        assert(link->network);
        assert(link->manager);

        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
                return;

        switch(event) {
        case SD_DHCP6_CLIENT_EVENT_STOP:
        case SD_DHCP6_CLIENT_EVENT_RESEND_EXPIRE:
        case SD_DHCP6_CLIENT_EVENT_RETRANS_MAX:
                log_link_warning(link, "DHCPv6 lease lost");

                link->dhcp6_configured = false;
                break;

        case SD_DHCP6_CLIENT_EVENT_IP_ACQUIRE:
                r = dhcp6_lease_address_acquired(client, link);
                if (r < 0) {
                        link_enter_failed(link);
                        return;
                }

                /* fall through */
        case SD_DHCP6_CLIENT_EVENT_INFORMATION_REQUEST:
                r = dhcp6_lease_information_acquired(client, link);
                if (r < 0) {
                        link_enter_failed(link);
                        return;
                }

                link->dhcp6_configured = true;
                break;

        default:
                if (event < 0)
                        log_link_warning_errno(link, event, "DHCPv6 error: %m");
                else
                        log_link_warning(link, "DHCPv6 unknown event: %d", event);
                return;
        }

        link_check_ready(link);
}

static int dhcp6_configure(Link *link, int event) {
        int r;
        bool information_request;

        assert_return(link, -EINVAL);
        assert_return(IN_SET(event, SD_NDISC_EVENT_ROUTER_ADVERTISMENT_TIMEOUT,
                             SD_NDISC_EVENT_ROUTER_ADVERTISMENT_OTHER,
                             SD_NDISC_EVENT_ROUTER_ADVERTISMENT_MANAGED), -EINVAL);

        link->dhcp6_configured = false;

        if (link->dhcp6_client) {
                r = sd_dhcp6_client_get_information_request(link->dhcp6_client,
                                                        &information_request);
                if (r < 0) {
                        log_link_warning_errno(link, r, "Could not get DHCPv6 Information request setting: %m");
                        goto error;
                }

                if (information_request && event != SD_NDISC_EVENT_ROUTER_ADVERTISMENT_OTHER) {
                        r = sd_dhcp6_client_stop(link->dhcp6_client);
                        if (r < 0) {
                                log_link_warning_errno(link, r, "Could not stop DHCPv6 while setting Managed mode: %m");
                                goto error;
                        }

                        r = sd_dhcp6_client_set_information_request(link->dhcp6_client,
                                                                    false);
                        if (r < 0) {
                                log_link_warning_errno(link, r, "Could not unset DHCPv6 Information request: %m");
                                goto error;
                        }

                }

                r = sd_dhcp6_client_start(link->dhcp6_client);
                if (r < 0 && r != -EALREADY) {
                        log_link_warning_errno(link, r, "Could not restart DHCPv6: %m");
                        goto error;
                }

                if (r == -EALREADY)
                        link->dhcp6_configured = true;

                return r;
        }

        r = sd_dhcp6_client_new(&link->dhcp6_client);
        if (r < 0)
                goto error;

        r = sd_dhcp6_client_attach_event(link->dhcp6_client, NULL, 0);
        if (r < 0)
                goto error;

        r = sd_dhcp6_client_set_mac(link->dhcp6_client,
                                    (const uint8_t *) &link->mac,
                                    sizeof (link->mac), ARPHRD_ETHER);
        if (r < 0)
                goto error;

        r = sd_dhcp6_client_set_index(link->dhcp6_client, link->ifindex);
        if (r < 0)
                goto error;

        r = sd_dhcp6_client_set_callback(link->dhcp6_client, dhcp6_handler,
                                         link);
        if (r < 0)
                goto error;

        if (event == SD_NDISC_EVENT_ROUTER_ADVERTISMENT_OTHER) {
                r = sd_dhcp6_client_set_information_request(link->dhcp6_client,
                                                        true);
                if (r < 0)
                        goto error;
        }

        r = sd_dhcp6_client_start(link->dhcp6_client);
        if (r < 0)
                goto error;

        return r;

 error:
        link->dhcp6_client = sd_dhcp6_client_unref(link->dhcp6_client);
        return r;
}

static int dhcp6_prefix_expired(Link *link) {
        int r;
        sd_dhcp6_lease *lease;
        struct in6_addr *expired_prefix, ip6_addr;
        uint8_t expired_prefixlen;
        uint32_t lifetime_preferred, lifetime_valid;

        r = sd_ndisc_get_expired_prefix(link->ndisc_router_discovery,
                                        &expired_prefix, &expired_prefixlen);
        if (r < 0)
                return r;

        r = sd_dhcp6_client_get_lease(link->dhcp6_client, &lease);
        if (r < 0)
                return r;

        log_link_info(link, "IPv6 prefix "SD_NDISC_ADDRESS_FORMAT_STR"/%d expired",
                      SD_NDISC_ADDRESS_FORMAT_VAL(*expired_prefix),
                      expired_prefixlen);

        sd_dhcp6_lease_reset_address_iter(lease);

        while (sd_dhcp6_lease_get_address(lease, &ip6_addr,
                                                &lifetime_preferred,
                                                &lifetime_valid) >= 0) {

                r = sd_ndisc_prefix_match(expired_prefix, expired_prefixlen,
                                        &ip6_addr);
                if (r < 0)
                        continue;

                log_link_info(link, "IPv6 prefix length updated "SD_NDISC_ADDRESS_FORMAT_STR"/%d", SD_NDISC_ADDRESS_FORMAT_VAL(ip6_addr), 128);

                dhcp6_address_change(link, &ip6_addr, 128, lifetime_preferred, lifetime_valid);
        }

        return 0;
}

static void ndisc_router_handler(sd_ndisc *nd, int event, void *userdata) {
        Link *link = userdata;

        assert(link);
        assert(link->network);
        assert(link->manager);

        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
                return;

        switch(event) {
        case SD_NDISC_EVENT_ROUTER_ADVERTISMENT_NONE:
                return;

        case SD_NDISC_EVENT_ROUTER_ADVERTISMENT_TIMEOUT:
        case SD_NDISC_EVENT_ROUTER_ADVERTISMENT_OTHER:
        case SD_NDISC_EVENT_ROUTER_ADVERTISMENT_MANAGED:
                dhcp6_configure(link, event);

                break;

        case SD_NDISC_EVENT_ROUTER_ADVERTISMENT_PREFIX_EXPIRED:
                if (!link->rtnl_extended_attrs)
                        dhcp6_prefix_expired(link);

                break;

        default:
                if (event < 0)
                        log_link_warning_errno(link, event, "IPv6 Neighborhood Discover error: %m");
                else
                        log_link_warning(link, "IPv6 Neighborhood Discovery unknown event: %d", event);

                break;
        }

}

int ndisc_configure(Link *link) {
        int r;

        assert_return(link, -EINVAL);

        r = sd_ndisc_new(&link->ndisc_router_discovery);
        if (r < 0)
                return r;

        r = sd_ndisc_attach_event(link->ndisc_router_discovery, NULL, 0);
        if (r < 0)
                return r;

        r = sd_ndisc_set_mac(link->ndisc_router_discovery, &link->mac);
        if (r < 0)
                return r;

        r = sd_ndisc_set_index(link->ndisc_router_discovery, link->ifindex);
        if (r < 0)
                return r;

        r = sd_ndisc_set_callback(link->ndisc_router_discovery,
                                  ndisc_router_handler, link);

        return r;
}