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Systemd/src/libsystemd-network/sd-ipv4ll.c

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/***
This file is part of systemd.
Copyright (C) 2014 Axis Communications AB. 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 <stdlib.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <arpa/inet.h>
#include "util.h"
#include "siphash24.h"
#include "list.h"
#include "refcnt.h"
#include "random-util.h"
#include "ipv4ll-internal.h"
#include "sd-ipv4ll.h"
/* Constants from the RFC */
#define PROBE_WAIT 1
#define PROBE_NUM 3
#define PROBE_MIN 1
#define PROBE_MAX 2
#define ANNOUNCE_WAIT 2
#define ANNOUNCE_NUM 2
#define ANNOUNCE_INTERVAL 2
#define MAX_CONFLICTS 10
#define RATE_LIMIT_INTERVAL 60
#define DEFEND_INTERVAL 10
#define IPV4LL_NETWORK 0xA9FE0000L
#define IPV4LL_NETMASK 0xFFFF0000L
typedef enum IPv4LLTrigger{
IPV4LL_TRIGGER_NULL,
IPV4LL_TRIGGER_PACKET,
IPV4LL_TRIGGER_TIMEOUT,
_IPV4LL_TRIGGER_MAX,
_IPV4LL_TRIGGER_INVALID = -1
} IPv4LLTrigger;
typedef enum IPv4LLState {
IPV4LL_STATE_INIT,
IPV4LL_STATE_WAITING_PROBE,
IPV4LL_STATE_PROBING,
IPV4LL_STATE_WAITING_ANNOUNCE,
IPV4LL_STATE_ANNOUNCING,
IPV4LL_STATE_RUNNING,
IPV4LL_STATE_STOPPED,
_IPV4LL_STATE_MAX,
_IPV4LL_STATE_INVALID = -1
} IPv4LLState;
struct sd_ipv4ll {
RefCount n_ref;
IPv4LLState state;
int index;
int fd;
union sockaddr_union link;
int iteration;
int conflict;
sd_event_source *receive_message;
sd_event_source *timer;
usec_t next_wakeup;
usec_t defend_window;
int next_wakeup_valid;
be32_t address;
struct random_data *random_data;
char *random_data_state;
/* External */
be32_t claimed_address;
struct ether_addr mac_addr;
sd_event *event;
int event_priority;
sd_ipv4ll_cb_t cb;
void* userdata;
};
static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data);
static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, int reset_counter) {
assert(ll);
assert(st < _IPV4LL_STATE_MAX);
if (st == ll->state && !reset_counter) {
ll->iteration++;
} else {
ll->state = st;
ll->iteration = 0;
}
}
static sd_ipv4ll *ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
assert(ll);
if (ll->cb) {
ll = sd_ipv4ll_ref(ll);
ll->cb(ll, event, ll->userdata);
ll = sd_ipv4ll_unref(ll);
}
return ll;
}
static sd_ipv4ll *ipv4ll_stop(sd_ipv4ll *ll, int event) {
assert(ll);
ll->receive_message = sd_event_source_unref(ll->receive_message);
ll->fd = safe_close(ll->fd);
ll->timer = sd_event_source_unref(ll->timer);
log_ipv4ll(ll, "STOPPED");
ll = ipv4ll_client_notify(ll, event);
if (ll) {
ll->claimed_address = 0;
ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
}
return ll;
}
static int ipv4ll_pick_address(sd_ipv4ll *ll, be32_t *address) {
be32_t addr;
int r;
int32_t random;
assert(ll);
assert(address);
assert(ll->random_data);
do {
r = random_r(ll->random_data, &random);
if (r < 0)
return r;
addr = htonl((random & 0x0000FFFF) | IPV4LL_NETWORK);
} while (addr == ll->address ||
(ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK ||
(ntohl(addr) & 0x0000FF00) == 0x0000 ||
(ntohl(addr) & 0x0000FF00) == 0xFF00);
*address = addr;
return 0;
}
static int ipv4ll_timer(sd_event_source *s, uint64_t usec, void *userdata) {
sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
assert(ll);
ll->next_wakeup_valid = 0;
ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_TIMEOUT, NULL);
return 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);
assert_se(sd_event_now(ll->event, clock_boottime_or_monotonic(), &time_now) >= 0);
ll->next_wakeup = time_now + next_timeout;
ll->next_wakeup_valid = 1;
}
static bool ipv4ll_arp_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
assert(ll);
assert(arp);
if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0 &&
memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN) != 0)
return true;
return false;
}
static bool ipv4ll_arp_probe_conflict (sd_ipv4ll *ll, struct ether_arp *arp) {
assert(ll);
assert(arp);
if (ipv4ll_arp_conflict(ll, arp))
return true;
if (memcmp(arp->arp_tpa, &ll->address, sizeof(ll->address)) == 0 &&
memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN))
return true;
return false;
}
static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) {
struct ether_arp out_packet;
int out_packet_ready = 0;
int r = 0;
assert(ll);
assert(trigger < _IPV4LL_TRIGGER_MAX);
if (ll->state == IPV4LL_STATE_INIT) {
log_ipv4ll(ll, "PROBE");
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
} else if ((ll->state == IPV4LL_STATE_WAITING_PROBE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
(ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < PROBE_NUM-2)) {
/* Send a probe */
arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, 0);
ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
} else if (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration >= PROBE_NUM-2) {
/* Send the last probe */
arp_packet_probe(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, 1);
ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
} else if ((ll->state == IPV4LL_STATE_WAITING_ANNOUNCE && trigger == IPV4LL_TRIGGER_TIMEOUT) ||
(ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < ANNOUNCE_NUM-1)) {
/* Send announcement packet */
arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, 0);
ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
if (ll->iteration == 0) {
log_ipv4ll(ll, "ANNOUNCE");
ll->claimed_address = ll->address;
ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
if (!ll || ll->state == IPV4LL_STATE_STOPPED)
goto out;
ll->conflict = 0;
}
} else if ((ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT &&
ll->iteration >= ANNOUNCE_NUM-1)) {
ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, 0);
ll->next_wakeup_valid = 0;
} else if (trigger == IPV4LL_TRIGGER_PACKET) {
int conflicted = 0;
usec_t time_now;
struct ether_arp* in_packet = (struct ether_arp*)trigger_data;
assert(in_packet);
if (IN_SET(ll->state, IPV4LL_STATE_ANNOUNCING, IPV4LL_STATE_RUNNING)) {
if (ipv4ll_arp_conflict(ll, in_packet)) {
r = sd_event_now(ll->event, clock_boottime_or_monotonic(), &time_now);
if (r < 0)
goto out;
/* Defend address */
if (time_now > ll->defend_window) {
ll->defend_window = time_now + DEFEND_INTERVAL * USEC_PER_SEC;
arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr);
out_packet_ready = 1;
} else
conflicted = 1;
}
} else if (IN_SET(ll->state, IPV4LL_STATE_WAITING_PROBE,
IPV4LL_STATE_PROBING,
IPV4LL_STATE_WAITING_ANNOUNCE)) {
conflicted = ipv4ll_arp_probe_conflict(ll, in_packet);
}
if (conflicted) {
log_ipv4ll(ll, "CONFLICT");
ll = ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
if (!ll || ll->state == IPV4LL_STATE_STOPPED)
goto out;
ll->claimed_address = 0;
/* Pick a new address */
r = ipv4ll_pick_address(ll, &ll->address);
if (r < 0)
goto out;
ll->conflict++;
ll->defend_window = 0;
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1);
if (ll->conflict >= MAX_CONFLICTS) {
log_ipv4ll(ll, "MAX_CONFLICTS");
ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
} else
ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
}
}
if (out_packet_ready) {
r = arp_network_send_raw_socket(ll->fd, &ll->link, &out_packet);
if (r < 0) {
log_ipv4ll(ll, "failed to send arp packet out");
goto out;
}
}
if (ll->next_wakeup_valid) {
ll->timer = sd_event_source_unref(ll->timer);
r = sd_event_add_time(ll->event, &ll->timer, clock_boottime_or_monotonic(),
ll->next_wakeup, 0, ipv4ll_timer, ll);
if (r < 0)
goto out;
r = sd_event_source_set_priority(ll->timer, ll->event_priority);
if (r < 0)
goto out;
r = sd_event_source_set_description(ll->timer, "ipv4ll-timer");
if (r < 0)
goto out;
}
out:
if (r < 0 && ll)
ipv4ll_stop(ll, r);
}
static int ipv4ll_receive_message(sd_event_source *s, int fd,
uint32_t revents, void *userdata) {
int r;
struct ether_arp arp;
sd_ipv4ll *ll = (sd_ipv4ll*)userdata;
assert(ll);
r = read(fd, &arp, sizeof(struct ether_arp));
if (r < (int) sizeof(struct ether_arp))
return 0;
r = arp_packet_verify_headers(&arp);
if (r < 0)
return 0;
ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_PACKET, &arp);
return 0;
}
int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) {
assert_return(ll, -EINVAL);
assert_return(interface_index > 0, -EINVAL);
assert_return(IN_SET(ll->state, IPV4LL_STATE_INIT,
IPV4LL_STATE_STOPPED), -EBUSY);
ll->index = interface_index;
return 0;
}
int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
bool need_restart = false;
assert_return(ll, -EINVAL);
assert_return(addr, -EINVAL);
if (memcmp(&ll->mac_addr, addr, ETH_ALEN) == 0)
return 0;
if (!IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED)) {
log_ipv4ll(ll, "Changing MAC address on running IPv4LL "
"client, restarting");
ll = ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
need_restart = true;
}
if (!ll)
return 0;
memcpy(&ll->mac_addr, addr, ETH_ALEN);
if (need_restart)
sd_ipv4ll_start(ll);
return 0;
}
int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
assert_return(ll, -EINVAL);
ll->event = sd_event_unref(ll->event);
return 0;
}
int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int priority) {
int r;
assert_return(ll, -EINVAL);
assert_return(!ll->event, -EBUSY);
if (event)
ll->event = sd_event_ref(event);
else {
r = sd_event_default(&ll->event);
if (r < 0) {
ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
return r;
}
}
ll->event_priority = priority;
return 0;
}
int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_cb_t cb, void *userdata) {
assert_return(ll, -EINVAL);
ll->cb = cb;
ll->userdata = userdata;
return 0;
}
int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address){
assert_return(ll, -EINVAL);
assert_return(address, -EINVAL);
if (ll->claimed_address == 0) {
return -ENOENT;
}
address->s_addr = ll->claimed_address;
return 0;
}
int sd_ipv4ll_set_address_seed (sd_ipv4ll *ll, uint8_t seed[8]) {
unsigned int entropy;
int r;
assert_return(ll, -EINVAL);
assert_return(seed, -EINVAL);
entropy = *seed;
free(ll->random_data);
free(ll->random_data_state);
ll->random_data = new0(struct random_data, 1);
ll->random_data_state = new0(char, 128);
if (!ll->random_data || !ll->random_data_state) {
r = -ENOMEM;
goto error;
}
r = initstate_r((unsigned int)entropy, ll->random_data_state, 128, ll->random_data);
if (r < 0)
goto error;
error:
if (r < 0){
free(ll->random_data);
free(ll->random_data_state);
ll->random_data = NULL;
ll->random_data_state = NULL;
}
return r;
}
bool sd_ipv4ll_is_running(sd_ipv4ll *ll) {
assert_return(ll, -EINVAL);
return !IN_SET(ll->state, IPV4LL_STATE_INIT, IPV4LL_STATE_STOPPED);
}
#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
int sd_ipv4ll_start (sd_ipv4ll *ll) {
int r;
assert_return(ll, -EINVAL);
assert_return(ll->event, -EINVAL);
assert_return(ll->index > 0, -EINVAL);
assert_return(IN_SET(ll->state, IPV4LL_STATE_INIT,
IPV4LL_STATE_STOPPED), -EBUSY);
ll->state = IPV4LL_STATE_INIT;
r = arp_network_bind_raw_socket(ll->index, &ll->link);
if (r < 0)
goto out;
ll->fd = r;
ll->conflict = 0;
ll->defend_window = 0;
ll->claimed_address = 0;
if (!ll->random_data) {
uint8_t seed[8];
/* Fallback to mac */
siphash24(seed, &ll->mac_addr.ether_addr_octet,
ETH_ALEN, HASH_KEY.bytes);
r = sd_ipv4ll_set_address_seed(ll, seed);
if (r < 0)
goto out;
}
if (ll->address == 0) {
r = ipv4ll_pick_address(ll, &ll->address);
if (r < 0)
goto out;
}
ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1);
r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
EPOLLIN, ipv4ll_receive_message, ll);
if (r < 0)
goto out;
r = sd_event_source_set_priority(ll->receive_message, ll->event_priority);
if (r < 0)
goto out;
r = sd_event_source_set_description(ll->receive_message, "ipv4ll-receive-message");
if (r < 0)
goto out;
r = sd_event_add_time(ll->event,
&ll->timer,
clock_boottime_or_monotonic(),
now(clock_boottime_or_monotonic()), 0,
ipv4ll_timer, ll);
if (r < 0)
goto out;
r = sd_event_source_set_priority(ll->timer, ll->event_priority);
if (r < 0)
goto out;
r = sd_event_source_set_description(ll->timer, "ipv4ll-timer");
out:
if (r < 0)
ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
return 0;
}
int sd_ipv4ll_stop(sd_ipv4ll *ll) {
ipv4ll_stop(ll, IPV4LL_EVENT_STOP);
if (ll)
ipv4ll_set_state(ll, IPV4LL_STATE_STOPPED, 1);
return 0;
}
sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
if (ll)
assert_se(REFCNT_INC(ll->n_ref) >= 2);
return ll;
}
sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
if (ll && REFCNT_DEC(ll->n_ref) == 0) {
ll->receive_message =
sd_event_source_unref(ll->receive_message);
ll->fd = safe_close(ll->fd);
ll->timer = sd_event_source_unref(ll->timer);
sd_ipv4ll_detach_event(ll);
free(ll->random_data);
free(ll->random_data_state);
free(ll);
return NULL;
}
return ll;
}
DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_unref);
#define _cleanup_ipv4ll_free_ _cleanup_(sd_ipv4ll_unrefp)
int sd_ipv4ll_new(sd_ipv4ll **ret) {
_cleanup_ipv4ll_free_ sd_ipv4ll *ll = NULL;
assert_return(ret, -EINVAL);
ll = new0(sd_ipv4ll, 1);
if (!ll)
return -ENOMEM;
ll->n_ref = REFCNT_INIT;
ll->state = IPV4LL_STATE_INIT;
ll->index = -1;
ll->fd = -1;
*ret = ll;
ll = NULL;
return 0;
}
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