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d1b0afe365
Add the core of DHCPv6 client message retransmission and upper bound timer and message count handling according to RFC 3315 Secions 7.1.2 and 14. Omit the DHCPv6 initial delay; for now it is assumed that systemd-networkd will provide decent startup randomization that will desynchronize the clients. When reinitializing the client, clear all timers.
439 lines
13 KiB
C
439 lines
13 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright (C) 2014 Intel Corporation. All rights reserved.
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <errno.h>
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#include <string.h>
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#include "udev.h"
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#include "udev-util.h"
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#include "virt.h"
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#include "siphash24.h"
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#include "util.h"
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#include "refcnt.h"
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#include "network-internal.h"
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#include "sd-dhcp6-client.h"
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#include "dhcp6-protocol.h"
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#include "dhcp6-internal.h"
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#define SYSTEMD_PEN 43793
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#define HASH_KEY SD_ID128_MAKE(80,11,8c,c2,fe,4a,03,ee,3e,d6,0c,6f,36,39,14,09)
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struct sd_dhcp6_client {
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RefCount n_ref;
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enum DHCP6State state;
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sd_event *event;
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int event_priority;
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int index;
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struct ether_addr mac_addr;
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DHCP6IA ia_na;
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usec_t retransmit_time;
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uint8_t retransmit_count;
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sd_event_source *timeout_resend;
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sd_event_source *timeout_resend_expire;
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sd_dhcp6_client_cb_t cb;
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void *userdata;
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struct duid_en {
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uint16_t type; /* DHCP6_DUID_EN */
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uint32_t pen;
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uint8_t id[8];
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} _packed_ duid;
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};
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int sd_dhcp6_client_set_callback(sd_dhcp6_client *client,
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sd_dhcp6_client_cb_t cb, void *userdata)
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{
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assert_return(client, -EINVAL);
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client->cb = cb;
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client->userdata = userdata;
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return 0;
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}
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int sd_dhcp6_client_set_index(sd_dhcp6_client *client, int interface_index)
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{
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assert_return(client, -EINVAL);
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assert_return(interface_index >= -1, -EINVAL);
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client->index = interface_index;
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return 0;
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}
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int sd_dhcp6_client_set_mac(sd_dhcp6_client *client,
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const struct ether_addr *mac_addr)
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{
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assert_return(client, -EINVAL);
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if (mac_addr)
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memcpy(&client->mac_addr, mac_addr, sizeof(client->mac_addr));
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else
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memset(&client->mac_addr, 0x00, sizeof(client->mac_addr));
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return 0;
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}
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static sd_dhcp6_client *client_notify(sd_dhcp6_client *client, int event) {
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if (client->cb) {
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client = sd_dhcp6_client_ref(client);
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client->cb(client, event, client->userdata);
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client = sd_dhcp6_client_unref(client);
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}
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return client;
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}
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static int client_initialize(sd_dhcp6_client *client)
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{
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assert_return(client, -EINVAL);
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client->ia_na.timeout_t1 =
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sd_event_source_unref(client->ia_na.timeout_t1);
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client->ia_na.timeout_t2 =
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sd_event_source_unref(client->ia_na.timeout_t2);
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client->retransmit_time = 0;
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client->retransmit_count = 0;
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client->timeout_resend = sd_event_source_unref(client->timeout_resend);
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client->timeout_resend_expire =
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sd_event_source_unref(client->timeout_resend_expire);
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client->state = DHCP6_STATE_STOPPED;
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return 0;
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}
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static sd_dhcp6_client *client_stop(sd_dhcp6_client *client, int error) {
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assert_return(client, NULL);
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client = client_notify(client, error);
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if (client)
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client_initialize(client);
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return client;
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}
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static int client_timeout_resend_expire(sd_event_source *s, uint64_t usec,
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void *userdata) {
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sd_dhcp6_client *client = userdata;
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assert(s);
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assert(client);
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assert(client->event);
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client_stop(client, DHCP6_EVENT_RESEND_EXPIRE);
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return 0;
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}
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static usec_t client_timeout_compute_random(usec_t val) {
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return val - val / 10 +
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(random_u32() % (2 * USEC_PER_SEC)) * val / 10 / USEC_PER_SEC;
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}
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static int client_timeout_resend(sd_event_source *s, uint64_t usec,
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void *userdata) {
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int r = 0;
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sd_dhcp6_client *client = userdata;
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usec_t time_now, init_retransmit_time, max_retransmit_time;
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usec_t max_retransmit_duration;
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uint8_t max_retransmit_count;
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char time_string[FORMAT_TIMESPAN_MAX];
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assert(s);
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assert(client);
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assert(client->event);
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client->timeout_resend = sd_event_source_unref(client->timeout_resend);
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switch (client->state) {
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case DHCP6_STATE_SOLICITATION:
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init_retransmit_time = DHCP6_SOL_TIMEOUT;
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max_retransmit_time = DHCP6_SOL_MAX_RT;
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max_retransmit_count = 0;
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max_retransmit_duration = 0;
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break;
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case DHCP6_STATE_STOPPED:
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case DHCP6_STATE_RS:
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return 0;
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}
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if (max_retransmit_count &&
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client->retransmit_count >= max_retransmit_count) {
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client_stop(client, DHCP6_EVENT_RETRANS_MAX);
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return 0;
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}
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r = sd_event_now(client->event, CLOCK_MONOTONIC, &time_now);
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if (r < 0)
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goto error;
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if (!client->retransmit_time) {
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client->retransmit_time =
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client_timeout_compute_random(init_retransmit_time);
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} else {
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if (max_retransmit_time &&
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client->retransmit_time > max_retransmit_time / 2)
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client->retransmit_time = client_timeout_compute_random(max_retransmit_time);
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else
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client->retransmit_time += client_timeout_compute_random(client->retransmit_time);
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}
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log_dhcp6_client(client, "Next retransmission in %s",
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format_timespan(time_string, FORMAT_TIMESPAN_MAX,
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client->retransmit_time, 0));
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r = sd_event_add_time(client->event, &client->timeout_resend,
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CLOCK_MONOTONIC,
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time_now + client->retransmit_time,
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10 * USEC_PER_MSEC, client_timeout_resend,
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client);
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if (r < 0)
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goto error;
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r = sd_event_source_set_priority(client->timeout_resend,
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client->event_priority);
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if (r < 0)
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goto error;
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if (max_retransmit_duration && !client->timeout_resend_expire) {
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log_dhcp6_client(client, "Max retransmission duration %"PRIu64" secs",
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max_retransmit_duration / USEC_PER_SEC);
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r = sd_event_add_time(client->event,
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&client->timeout_resend_expire,
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CLOCK_MONOTONIC,
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time_now + max_retransmit_duration,
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USEC_PER_SEC,
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client_timeout_resend_expire, client);
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if (r < 0)
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goto error;
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r = sd_event_source_set_priority(client->timeout_resend_expire,
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client->event_priority);
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if (r < 0)
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goto error;
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}
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error:
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if (r < 0)
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client_stop(client, r);
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return 0;
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}
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static int client_ensure_iaid(sd_dhcp6_client *client) {
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const char *name = NULL;
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uint64_t id;
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assert(client);
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if (client->ia_na.id)
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return 0;
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if (detect_container(NULL) <= 0) {
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/* not in a container, udev will be around */
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_cleanup_udev_unref_ struct udev *udev;
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_cleanup_udev_device_unref_ struct udev_device *device;
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char ifindex_str[2 + DECIMAL_STR_MAX(int)];
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udev = udev_new();
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if (!udev)
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return -ENOMEM;
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sprintf(ifindex_str, "n%d", client->index);
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device = udev_device_new_from_device_id(udev, ifindex_str);
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if (!device)
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return -errno;
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if (udev_device_get_is_initialized(device) <= 0)
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/* not yet ready */
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return -EBUSY;
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name = net_get_name(device);
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}
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if (name)
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siphash24((uint8_t*)&id, name, strlen(name), HASH_KEY.bytes);
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else
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/* fall back to mac address if no predictable name available */
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siphash24((uint8_t*)&id, &client->mac_addr, ETH_ALEN,
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HASH_KEY.bytes);
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/* fold into 32 bits */
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client->ia_na.id = (id & 0xffffffff) ^ (id >> 32);
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return 0;
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}
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static int client_start(sd_dhcp6_client *client)
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{
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int r;
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assert_return(client, -EINVAL);
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assert_return(client->event, -EINVAL);
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assert_return(client->index > 0, -EINVAL);
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r = client_ensure_iaid(client);
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if (r < 0)
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return r;
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client->state = DHCP6_STATE_SOLICITATION;
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r = sd_event_add_time(client->event, &client->timeout_resend,
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CLOCK_MONOTONIC, 0, 0, client_timeout_resend,
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client);
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if (r < 0)
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return r;
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r = sd_event_source_set_priority(client->timeout_resend,
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client->event_priority);
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if (r < 0)
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return r;
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return 0;
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}
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int sd_dhcp6_client_stop(sd_dhcp6_client *client)
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{
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client_stop(client, DHCP6_EVENT_STOP);
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return 0;
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}
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int sd_dhcp6_client_start(sd_dhcp6_client *client)
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{
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int r = 0;
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assert_return(client, -EINVAL);
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assert_return(client->event, -EINVAL);
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assert_return(client->index > 0, -EINVAL);
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r = client_initialize(client);
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if (r < 0)
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return r;
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return client_start(client);
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}
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int sd_dhcp6_client_attach_event(sd_dhcp6_client *client, sd_event *event,
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int priority)
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{
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int r;
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assert_return(client, -EINVAL);
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assert_return(!client->event, -EBUSY);
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if (event)
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client->event = sd_event_ref(event);
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else {
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r = sd_event_default(&client->event);
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if (r < 0)
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return 0;
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}
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client->event_priority = priority;
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return 0;
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}
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int sd_dhcp6_client_detach_event(sd_dhcp6_client *client) {
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assert_return(client, -EINVAL);
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client->event = sd_event_unref(client->event);
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return 0;
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}
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sd_event *sd_dhcp6_client_get_event(sd_dhcp6_client *client) {
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if (!client)
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return NULL;
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return client->event;
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}
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sd_dhcp6_client *sd_dhcp6_client_ref(sd_dhcp6_client *client) {
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if (client)
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assert_se(REFCNT_INC(client->n_ref) >= 2);
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return client;
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}
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sd_dhcp6_client *sd_dhcp6_client_unref(sd_dhcp6_client *client) {
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if (client && REFCNT_DEC(client->n_ref) <= 0) {
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client_initialize(client);
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sd_dhcp6_client_detach_event(client);
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free(client);
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return NULL;
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}
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return client;
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}
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DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp6_client*, sd_dhcp6_client_unref);
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#define _cleanup_dhcp6_client_free_ _cleanup_(sd_dhcp6_client_unrefp)
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int sd_dhcp6_client_new(sd_dhcp6_client **ret)
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{
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_cleanup_dhcp6_client_free_ sd_dhcp6_client *client = NULL;
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sd_id128_t machine_id;
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int r;
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assert_return(ret, -EINVAL);
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client = new0(sd_dhcp6_client, 1);
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if (!client)
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return -ENOMEM;
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client->n_ref = REFCNT_INIT;
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client->ia_na.type = DHCP6_OPTION_IA_NA;
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client->index = -1;
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/* initialize DUID */
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client->duid.type = htobe16(DHCP6_DUID_EN);
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client->duid.pen = htobe32(SYSTEMD_PEN);
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r = sd_id128_get_machine(&machine_id);
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if (r < 0)
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return r;
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/* a bit of snake-oil perhaps, but no need to expose the machine-id
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directly */
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siphash24(client->duid.id, &machine_id, sizeof(machine_id),
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HASH_KEY.bytes);
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*ret = client;
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client = NULL;
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return 0;
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}
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