static int curl_glue_timer_callback(CURLM *curl, long timeout_ms, void *userdata) {
        CurlGlue *g = userdata;
        usec_t usec;

        assert(curl);
        assert(g);

        if (timeout_ms < 0) {
                if (g->timer) {
                        if (sd_event_source_set_enabled(g->timer, SD_EVENT_OFF) < 0)
                                return -1;
                }

                return 0;
        }

        usec = now(clock_boottime_or_monotonic()) + (usec_t) timeout_ms * USEC_PER_MSEC + USEC_PER_MSEC - 1;

        if (g->timer) {
                if (sd_event_source_set_time(g->timer, usec) < 0)
                        return -1;

                if (sd_event_source_set_enabled(g->timer, SD_EVENT_ONESHOT) < 0)
                        return -1;
        } else {
                if (sd_event_add_time(g->event, &g->timer, clock_boottime_or_monotonic(), usec, 0, curl_glue_on_timer, g) < 0)
                        return -1;

                (void) sd_event_source_set_description(g->timer, "curl-timer");
        }

        return 0;
}

static int pppoe_arm_timeout(sd_pppoe *ppp) {
        _cleanup_event_source_unref_ sd_event_source *timeout = NULL;
        usec_t next_timeout;
        int r;

        assert(ppp);

        r = sd_event_now(ppp->event, clock_boottime_or_monotonic(), &next_timeout);
        if (r == -ENODATA)
                next_timeout = now(clock_boottime_or_monotonic());
        else if (r < 0)
                return r;

        next_timeout += 500 * USEC_PER_MSEC;

        r = sd_event_add_time(ppp->event, &timeout, clock_boottime_or_monotonic(), next_timeout,
                              10 * USEC_PER_MSEC, pppoe_timeout, ppp);
        if (r < 0)
                return r;

        r = sd_event_source_set_priority(timeout, ppp->event_priority);
        if (r < 0)
                return r;

        sd_event_source_unref(ppp->timeout);
        ppp->timeout = timeout;
        timeout = NULL;

        return 0;
}

static int ipv4acd_set_next_wakeup(sd_ipv4acd *acd, usec_t usec, usec_t random_usec) {
        _cleanup_(sd_event_source_unrefp) sd_event_source *timer = NULL;
        usec_t next_timeout, time_now;
        int r;

        assert(acd);

        next_timeout = usec;

        if (random_usec > 0)
                next_timeout += (usec_t) random_u64() % random_usec;

        assert_se(sd_event_now(acd->event, clock_boottime_or_monotonic(), &time_now) >= 0);

        r = sd_event_add_time(acd->event, &timer, clock_boottime_or_monotonic(), time_now + next_timeout, 0, ipv4acd_on_timeout, acd);
        if (r < 0)
                return r;

        r = sd_event_source_set_priority(timer, acd->event_priority);
        if (r < 0)
                return r;

        (void) sd_event_source_set_description(timer, "ipv4acd-timer");

        sd_event_source_unref(acd->timer_event_source);
        acd->timer_event_source = timer;
        timer = NULL;

        return 0;
}

static int on_lldp_timer(sd_event_source *s, usec_t t, void *userdata) {
        Link *link = userdata;
        usec_t current, delay, next;
        int r;

        assert(s);
        assert(userdata);

        log_link_debug(link, "Sending LLDP packet...");

        r = link_send_lldp(link);
        if (r < 0)
                log_link_debug_errno(link, r, "Failed to send LLDP packet, ignoring: %m");

        if (link->lldp_tx_fast > 0)
                link->lldp_tx_fast--;

        assert_se(sd_event_now(sd_event_source_get_event(s), clock_boottime_or_monotonic(), &current) >= 0);

        delay = link->lldp_tx_fast > 0 ? LLDP_FAST_TX_USEC : LLDP_TX_INTERVAL_USEC;
        next = usec_add(usec_add(current, delay), (usec_t) random_u64() % LLDP_JITTER_USEC);

        r = sd_event_source_set_time(s, next);
        if (r < 0)
                return log_link_error_errno(link, r, "Failed to restart LLDP timer: %m");

        r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
        if (r < 0)
                return log_link_error_errno(link, r, "Failed to enable LLDP timer: %m");

        return 0;
}

static int lldp_make_space(sd_lldp *lldp, size_t extra) {
        usec_t t = USEC_INFINITY;
        bool changed = false;

        assert(lldp);

        /* Remove all entries that are past their TTL, and more until at least the specified number of extra entries
         * are free. */

        for (;;) {
                _cleanup_(sd_lldp_neighbor_unrefp) sd_lldp_neighbor *n = NULL;

                n = prioq_peek(lldp->neighbor_by_expiry);
                if (!n)
                        break;

                sd_lldp_neighbor_ref(n);

                if (hashmap_size(lldp->neighbor_by_id) > LESS_BY(lldp->neighbors_max, extra))
                        goto remove_one;

                if (t == USEC_INFINITY)
                        t = now(clock_boottime_or_monotonic());

                if (n->until > t)
                        break;

        remove_one:
                lldp_neighbor_unlink(n);
                lldp_callback(lldp, SD_LLDP_EVENT_REMOVED, n);
                changed = true;
        }

        return changed;
}

int link_lldp_emit_start(Link *link) {
        usec_t next;
        int r;

        assert(link);

        if (!link->network || link->network->lldp_emit == LLDP_EMIT_NO) {
                link_lldp_emit_stop(link);
                return 0;
        }

        /* Starts the LLDP transmission in "fast" mode. If it is already started, turns "fast" mode back on again. */

        link->lldp_tx_fast = LLDP_TX_FAST_INIT;

        next = usec_add(usec_add(now(clock_boottime_or_monotonic()), LLDP_FAST_TX_USEC),
                     (usec_t) random_u64() % LLDP_JITTER_USEC);

        if (link->lldp_emit_event_source) {
                usec_t old;

                /* Lower the timeout, maybe */
                r = sd_event_source_get_time(link->lldp_emit_event_source, &old);
                if (r < 0)
                        return r;

                if (old <= next)
                        return 0;

                return sd_event_source_set_time(link->lldp_emit_event_source, next);
        } else {
                r = sd_event_add_time(
                                link->manager->event,
                                &link->lldp_emit_event_source,
                                clock_boottime_or_monotonic(),
                                next,
                                0,
                                on_lldp_timer,
                                link);
                if (r < 0)
                        return r;

                (void) sd_event_source_set_description(link->lldp_emit_event_source, "lldp-tx");
        }

        return 0;
}

static int test_client_solicit(sd_event *e) {
        sd_dhcp6_client *client;
        usec_t time_now = now(clock_boottime_or_monotonic());
        struct in6_addr address = { { { 0xfe, 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01 } } };
        int val;

        if (verbose)
                printf("* %s\n", __FUNCTION__);

        assert_se(sd_dhcp6_client_new(&client) >= 0);
        assert_se(client);

        assert_se(sd_dhcp6_client_attach_event(client, e, 0) >= 0);

        assert_se(sd_dhcp6_client_set_ifindex(client, test_index) == 0);
        assert_se(sd_dhcp6_client_set_mac(client, (const uint8_t *) &mac_addr,
                                          sizeof (mac_addr),
                                          ARPHRD_ETHER) >= 0);
        assert_se(sd_dhcp6_client_set_fqdn(client, "host.lab.intra") == 1);

        assert_se(sd_dhcp6_client_get_information_request(client, &val) >= 0);
        assert_se(val == 0);
        assert_se(sd_dhcp6_client_set_information_request(client, 42) >= 0);
        assert_se(sd_dhcp6_client_get_information_request(client, &val) >= 0);
        assert_se(val);

        assert_se(sd_dhcp6_client_set_callback(client,
                                               test_client_information_cb, e) >= 0);

        assert_se(sd_event_add_time(e, &hangcheck, clock_boottime_or_monotonic(),
                                    time_now + 2 * USEC_PER_SEC, 0,
                                    test_hangcheck, NULL) >= 0);

        assert_se(sd_dhcp6_client_set_local_address(client, &address) >= 0);

        assert_se(sd_dhcp6_client_start(client) >= 0);

        sd_event_loop(e);

        hangcheck = sd_event_source_unref(hangcheck);

        assert_se(!sd_dhcp6_client_unref(client));

        test_dhcp_fd[1] = safe_close(test_dhcp_fd[1]);

        return 0;
}

static void ndisc_router_process_default(Link *link, sd_ndisc_router *rt) {
        _cleanup_route_free_ Route *route = NULL;
        struct in6_addr gateway;
        uint16_t lifetime;
        unsigned preference;
        usec_t time_now;
        int r;

        assert(link);
        assert(rt);

        r = sd_ndisc_router_get_lifetime(rt, &lifetime);
        if (r < 0) {
                log_link_warning_errno(link, r, "Failed to get gateway address from RA: %m");
                return;
        }
        if (lifetime == 0) /* not a default router */
                return;

        r = sd_ndisc_router_get_address(rt, &gateway);
        if (r < 0) {
                log_link_warning_errno(link, r, "Failed to get gateway address from RA: %m");
                return;
        }

        r = sd_ndisc_router_get_preference(rt, &preference);
        if (r < 0) {
                log_link_warning_errno(link, r, "Failed to get default router preference from RA: %m");
                return;
        }

        r = sd_ndisc_router_get_timestamp(rt, clock_boottime_or_monotonic(), &time_now);
        if (r < 0) {
                log_link_warning_errno(link, r, "Failed to get RA timestamp: %m");
                return;
        }

        r = route_new(&route);
        if (r < 0) {
                log_link_error_errno(link, r, "Could not allocate route: %m");
                return;
        }

        route->family = AF_INET6;
        route->table = RT_TABLE_MAIN;
        route->protocol = RTPROT_RA;
        route->pref = preference;
        route->gw.in6 = gateway;
        route->lifetime = time_now + lifetime * USEC_PER_SEC;

        r = route_configure(route, link, ndisc_netlink_handler);
        if (r < 0) {
                log_link_warning_errno(link, r, "Could not set default route: %m");
                link_enter_failed(link);
                return;
        }

        link->ndisc_messages++;
}

static void ndisc_router_process_onlink_prefix(Link *link, sd_ndisc_router *rt) {
        _cleanup_route_free_ Route *route = NULL;
        usec_t time_now;
        uint32_t lifetime;
        unsigned prefixlen;
        int r;

        assert(link);
        assert(rt);

        r = sd_ndisc_router_get_timestamp(rt, clock_boottime_or_monotonic(), &time_now);
        if (r < 0) {
                log_link_warning_errno(link, r, "Failed to get RA timestamp: %m");
                return;
        }

        r = sd_ndisc_router_prefix_get_prefixlen(rt, &prefixlen);
        if (r < 0) {
                log_link_error_errno(link, r, "Failed to get prefix length: %m");
                return;
        }

        r = sd_ndisc_router_prefix_get_valid_lifetime(rt, &lifetime);
        if (r < 0) {
                log_link_error_errno(link, r, "Failed to get prefix lifetime: %m");
                return;
        }

        r = route_new(&route);
        if (r < 0) {
                log_link_error_errno(link, r, "Could not allocate route: %m");
                return;
        }

        route->family = AF_INET6;
        route->table = RT_TABLE_MAIN;
        route->protocol = RTPROT_RA;
        route->flags = RTM_F_PREFIX;
        route->dst_prefixlen = prefixlen;
        route->lifetime = time_now + lifetime * USEC_PER_SEC;

        r = sd_ndisc_router_prefix_get_address(rt, &route->dst.in6);
        if (r < 0) {
                log_link_error_errno(link, r, "Failed to get prefix address: %m");
                return;
        }

        r = route_configure(route, link, ndisc_netlink_handler);
        if (r < 0) {
                log_link_warning_errno(link, r, "Could not set prefix route: %m");
                link_enter_failed(link);
                return;
        }

        link->ndisc_messages++;
}

static void test_addr_acq(sd_event *e) {
        usec_t time_now = now(clock_boottime_or_monotonic());
        sd_dhcp_client *client;
        int res, r;

        if (verbose)
                printf("* %s\n", __FUNCTION__);

        r = sd_dhcp_client_new(&client, false);
        assert_se(r >= 0);
        assert_se(client);

        r = sd_dhcp_client_attach_event(client, e, 0);
        assert_se(r >= 0);

        assert_se(sd_dhcp_client_set_ifindex(client, 42) >= 0);
        assert_se(sd_dhcp_client_set_mac(client, mac_addr, ETH_ALEN, ARPHRD_ETHER) >= 0);

        assert_se(sd_dhcp_client_set_callback(client, test_addr_acq_acquired, e) >= 0);

        callback_recv = test_addr_acq_recv_discover;

        assert_se(sd_event_add_time(e, &test_hangcheck,
                                    clock_boottime_or_monotonic(),
                                    time_now + 2 * USEC_PER_SEC, 0,
                                    test_dhcp_hangcheck, NULL) >= 0);

        res = sd_dhcp_client_start(client);
        assert_se(IN_SET(res, 0, -EINPROGRESS));

        assert_se(sd_event_loop(e) >= 0);

        test_hangcheck = sd_event_source_unref(test_hangcheck);

        assert_se(sd_dhcp_client_set_callback(client, NULL, NULL) >= 0);
        assert_se(sd_dhcp_client_stop(client) >= 0);
        sd_dhcp_client_unref(client);

        test_fd[1] = safe_close(test_fd[1]);

        callback_recv = NULL;
        xid = 0;
}

static void ipv4ll_set_next_wakeup(sd_ipv4ll *ll, int sec, int random_sec) {
    usec_t next_timeout = 0;
    usec_t time_now = 0;

    assert(sec >= 0);
    assert(random_sec >= 0);
    assert(ll);

    next_timeout = sec * USEC_PER_SEC;

    if (random_sec)
        next_timeout += random_u32() % (random_sec * USEC_PER_SEC);

    if (sd_event_now(ll->event, clock_boottime_or_monotonic(), &time_now) < 0)
        time_now = now(clock_boottime_or_monotonic());

    ll->next_wakeup = time_now + next_timeout;
    ll->next_wakeup_valid = 1;
}

static void test_rs(void) {
        sd_event *e;
        sd_icmp6_nd *nd;
        usec_t time_now = now(clock_boottime_or_monotonic());

        if (verbose)
                printf("* %s\n", __FUNCTION__);

        send_ra_function = send_ra;

        assert_se(sd_event_new(&e) >= 0);

        assert_se(sd_icmp6_nd_new(&nd) >= 0);
        assert_se(nd);

        assert_se(sd_icmp6_nd_attach_event(nd, e, 0) >= 0);

        assert_se(sd_icmp6_nd_set_index(nd, 42) >= 0);
        assert_se(sd_icmp6_nd_set_mac(nd, &mac_addr) >= 0);
        assert_se(sd_icmp6_nd_set_callback(nd, test_rs_done, e) >= 0);

        assert_se(sd_event_add_time(e, &test_hangcheck, clock_boottime_or_monotonic(),
                                 time_now + 2 *USEC_PER_SEC, 0,
                                 test_rs_hangcheck, NULL) >= 0);

        assert_se(sd_icmp6_nd_stop(nd) >= 0);
        assert_se(sd_icmp6_router_solicitation_start(nd) >= 0);
        assert_se(sd_icmp6_nd_stop(nd) >= 0);

        assert_se(sd_icmp6_router_solicitation_start(nd) >= 0);

        sd_event_loop(e);

        test_hangcheck = sd_event_source_unref(test_hangcheck);

        nd = sd_icmp6_nd_unref(nd);
        assert_se(!nd);

        close(test_fd[1]);

        sd_event_unref(e);
}

static void test_usec_shift_clock(void) {
        usec_t rt, mn, bt;

        log_info("/* %s */", __func__);

        rt = now(CLOCK_REALTIME);
        mn = now(CLOCK_MONOTONIC);
        bt = now(clock_boottime_or_monotonic());

        assert_se(usec_shift_clock(USEC_INFINITY, CLOCK_REALTIME, CLOCK_MONOTONIC) == USEC_INFINITY);

        assert_similar(usec_shift_clock(rt + USEC_PER_HOUR, CLOCK_REALTIME, CLOCK_MONOTONIC), mn + USEC_PER_HOUR);
        assert_similar(usec_shift_clock(rt + 2*USEC_PER_HOUR, CLOCK_REALTIME, clock_boottime_or_monotonic()), bt + 2*USEC_PER_HOUR);
        assert_se(usec_shift_clock(rt + 3*USEC_PER_HOUR, CLOCK_REALTIME, CLOCK_REALTIME_ALARM) == rt + 3*USEC_PER_HOUR);

        assert_similar(usec_shift_clock(mn + 4*USEC_PER_HOUR, CLOCK_MONOTONIC, CLOCK_REALTIME_ALARM), rt + 4*USEC_PER_HOUR);
        assert_similar(usec_shift_clock(mn + 5*USEC_PER_HOUR, CLOCK_MONOTONIC, clock_boottime_or_monotonic()), bt + 5*USEC_PER_HOUR);
        assert_se(usec_shift_clock(mn + 6*USEC_PER_HOUR, CLOCK_MONOTONIC, CLOCK_MONOTONIC) == mn + 6*USEC_PER_HOUR);

        assert_similar(usec_shift_clock(bt + 7*USEC_PER_HOUR, clock_boottime_or_monotonic(), CLOCK_MONOTONIC), mn + 7*USEC_PER_HOUR);
        assert_similar(usec_shift_clock(bt + 8*USEC_PER_HOUR, clock_boottime_or_monotonic(), CLOCK_REALTIME_ALARM), rt + 8*USEC_PER_HOUR);
        assert_se(usec_shift_clock(bt + 9*USEC_PER_HOUR, clock_boottime_or_monotonic(), clock_boottime_or_monotonic()) == bt + 9*USEC_PER_HOUR);

        if (mn > USEC_PER_MINUTE) {
                assert_similar(usec_shift_clock(rt - 30 * USEC_PER_SEC, CLOCK_REALTIME_ALARM, CLOCK_MONOTONIC), mn - 30 * USEC_PER_SEC);
                assert_similar(usec_shift_clock(rt - 50 * USEC_PER_SEC, CLOCK_REALTIME, clock_boottime_or_monotonic()), bt - 50 * USEC_PER_SEC);
        }
}

int sd_icmp6_router_solicitation_start(sd_icmp6_nd *nd) {
        int r;

        assert(nd);
        assert(nd->event);

        if (nd->state != ICMP6_NEIGHBOR_DISCOVERY_IDLE)
                return -EINVAL;

        if (nd->index < 1)
                return -EINVAL;

        r = dhcp_network_icmp6_bind_router_solicitation(nd->index);
        if (r < 0)
                return r;

        nd->fd = r;

        r = sd_event_add_io(nd->event, &nd->recv, nd->fd, EPOLLIN,
                            icmp6_router_advertisment_recv, nd);
        if (r < 0)
                goto error;

        r = sd_event_source_set_priority(nd->recv, nd->event_priority);
        if (r < 0)
                goto error;

        r = sd_event_source_set_description(nd->recv, "icmp6-receive-message");
        if (r < 0)
                goto error;

        r = sd_event_add_time(nd->event, &nd->timeout, clock_boottime_or_monotonic(),
                              0, 0, icmp6_router_solicitation_timeout, nd);
        if (r < 0)
                goto error;

        r = sd_event_source_set_priority(nd->timeout, nd->event_priority);
        if (r < 0)
                goto error;

        r = sd_event_source_set_description(nd->timeout, "icmp6-timeout");
error:
        if (r < 0)
                icmp6_nd_init(nd);
        else
                log_icmp6_nd(client, "Start Router Solicitation");

        return r;
}

dual_timestamp* dual_timestamp_from_boottime_or_monotonic(dual_timestamp *ts, usec_t u) {
        int64_t delta;

        if (u == USEC_INFINITY) {
                ts->realtime = ts->monotonic = USEC_INFINITY;
                return ts;
        }

        dual_timestamp_get(ts);
        delta = (int64_t) now(clock_boottime_or_monotonic()) - (int64_t) u;
        ts->realtime = usec_sub(ts->realtime, delta);
        ts->monotonic = usec_sub(ts->monotonic, delta);

        return ts;
}

static void dns_server_verified(DnsServer *s, DnsServerFeatureLevel level) {
        assert(s);

        if (s->verified_feature_level > level)
                return;

        if (s->verified_feature_level != level) {
                log_debug("Verified we get a response at feature level %s from DNS server %s.",
                          dns_server_feature_level_to_string(level),
                          dns_server_string(s));
                s->verified_feature_level = level;
        }

        assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &s->verified_usec) >= 0);
}

static int ipv4acd_set_next_wakeup(sd_ipv4acd *ll, int sec, int random_sec) {
        _cleanup_(sd_event_source_unrefp) sd_event_source *timer = NULL;
        usec_t next_timeout;
        usec_t time_now;
        int r;

        assert(sec >= 0);
        assert(random_sec >= 0);
        assert(ll);

        next_timeout = sec * USEC_PER_SEC;

        if (random_sec)
                next_timeout += random_u32() % (random_sec * USEC_PER_SEC);

        assert_se(sd_event_now(ll->event, clock_boottime_or_monotonic(), &time_now) >= 0);

        r = sd_event_add_time(ll->event, &timer, clock_boottime_or_monotonic(),
                              time_now + next_timeout, 0, ipv4acd_on_timeout, ll);
        if (r < 0)
                return r;

        r = sd_event_source_set_priority(timer, ll->event_priority);
        if (r < 0)
                return r;

        r = sd_event_source_set_description(timer, "ipv4acd-timer");
        if (r < 0)
                return r;

        ll->timer = sd_event_source_unref(ll->timer);
        ll->timer = timer;
        timer = NULL;

        return 0;
}

static bool dns_server_grace_period_expired(DnsServer *s) {
        usec_t ts;

        assert(s);
        assert(s->manager);

        if (s->verified_usec == 0)
                return false;

        assert_se(sd_event_now(s->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);

        if (s->verified_usec + s->features_grace_period_usec > ts)
                return false;

        s->features_grace_period_usec = MIN(s->features_grace_period_usec * 2, DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC);

        return true;
}

static int lldp_start_timer(sd_lldp *lldp, sd_lldp_neighbor *neighbor) {
        sd_lldp_neighbor *n;
        int r;

        assert(lldp);

        if (neighbor)
                lldp_neighbor_start_ttl(neighbor);

        n = prioq_peek(lldp->neighbor_by_expiry);
        if (!n) {

                if (lldp->timer_event_source)
                        return sd_event_source_set_enabled(lldp->timer_event_source, SD_EVENT_OFF);

                return 0;
        }

        if (lldp->timer_event_source) {
                r = sd_event_source_set_time(lldp->timer_event_source, n->until);
                if (r < 0)
                        return r;

                return sd_event_source_set_enabled(lldp->timer_event_source, SD_EVENT_ONESHOT);
        }

        if (!lldp->event)
                return 0;

        r = sd_event_add_time(lldp->event, &lldp->timer_event_source, clock_boottime_or_monotonic(), n->until, 0, on_timer_event, lldp);
        if (r < 0)
                return r;

        r = sd_event_source_set_priority(lldp->timer_event_source, lldp->event_priority);
        if (r < 0)
                return r;

        (void) sd_event_source_set_description(lldp->timer_event_source, "lldp-timer");
        return 0;
}

static clockid_t map_clock_id(clockid_t c) {

        /* Some more exotic archs (s390, ppc, …) lack the "ALARM" flavour of the clocks. Thus, clock_gettime() will
         * fail for them. Since they are essentially the same as their non-ALARM pendants (their only difference is
         * when timers are set on them), let's just map them accordingly. This way, we can get the correct time even on
         * those archs.
         *
         * Also, older kernels don't support CLOCK_BOOTTIME: fall back to CLOCK_MONOTONIC. */

        switch (c) {

        case CLOCK_BOOTTIME:
        case CLOCK_BOOTTIME_ALARM:
                return clock_boottime_or_monotonic ();

        case CLOCK_REALTIME_ALARM:
                return CLOCK_REALTIME;

        default:
                return c;
        }
}