sd-ipv4ll.c revision 6af9144f5ff65cb9f6ae9999e7e0a9edc4841b2b
/***
This file is part of systemd.
Copyright (C) 2014 Axis Communications AB. All rights reserved.
Copyright (C) 2015 Tom Gundersen
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 "random-util.h"
#include "event-util.h"
#include "arp-util.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
#define log_ipv4ll(ll, fmt, ...) log_internal(LOG_DEBUG, 0, __FILE__, __LINE__, __func__, "IPv4LL: " fmt, ##__VA_ARGS__)
#define IPV4LL_DONT_DESTROY(ll) \
_cleanup_ipv4ll_unref_ _unused_ sd_ipv4ll *_dont_destroy_##ll = sd_ipv4ll_ref(ll)
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_MAX,
_IPV4LL_STATE_INVALID = -1
} IPv4LLState;
struct sd_ipv4ll {
unsigned n_ref;
IPv4LLState state;
int index;
int fd;
int iteration;
int conflict;
sd_event_source *receive_message;
sd_event_source *timer;
usec_t defend_window;
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;
};
sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
if (!ll)
return NULL;
assert(ll->n_ref >= 1);
ll->n_ref++;
return ll;
}
sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
if (!ll)
return NULL;
assert(ll->n_ref >= 1);
ll->n_ref--;
if (ll->n_ref > 0)
return NULL;
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;
}
DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_unref);
#define _cleanup_ipv4ll_unref_ _cleanup_(sd_ipv4ll_unrefp)
int sd_ipv4ll_new(sd_ipv4ll **ret) {
_cleanup_ipv4ll_unref_ sd_ipv4ll *ll = NULL;
assert_return(ret, -EINVAL);
ll = new0(sd_ipv4ll, 1);
if (!ll)
return -ENOMEM;
ll->n_ref = 1;
ll->state = IPV4LL_STATE_INIT;
ll->index = -1;
ll->fd = -1;
*ret = ll;
ll = NULL;
return 0;
}
static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, bool 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 void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
assert(ll);
if (ll->cb)
ll->cb(ll, event, ll->userdata);
}
static void ipv4ll_stop(sd_ipv4ll *ll) {
IPV4LL_DONT_DESTROY(ll);
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->claimed_address = 0;
ipv4ll_set_state (ll, IPV4LL_STATE_INIT, true);
}
int sd_ipv4ll_stop(sd_ipv4ll *ll) {
IPV4LL_DONT_DESTROY(ll);
assert_return(ll, -EINVAL);
ipv4ll_stop(ll);
ipv4ll_client_notify(ll, IPV4LL_EVENT_STOP);
return 0;
}
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_on_timeout(sd_event_source *s, uint64_t usec, void *userdata);
static int ipv4ll_set_next_wakeup(sd_ipv4ll *ll, int sec, int random_sec) {
_cleanup_event_source_unref_ 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, ipv4ll_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, "ipv4ll-timer");
if (r < 0)
return r;
ll->timer = sd_event_source_unref(ll->timer);
ll->timer = timer;
timer = NULL;
return 0;
}
static bool ipv4ll_arp_conflict(sd_ipv4ll *ll, struct ether_arp *arp) {
assert(ll);
assert(arp);
/* see the BPF */
if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0)
return true;
/* the TPA matched instead of the SPA, this is not a conflict */
return false;
}
static int ipv4ll_on_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
sd_ipv4ll *ll = userdata;
int r = 0;
assert(ll);
switch (ll->state) {
case IPV4LL_STATE_INIT:
log_ipv4ll(ll, "PROBE");
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, true);
if (ll->conflict >= MAX_CONFLICTS) {
log_ipv4ll(ll, "MAX_CONFLICTS");
r = ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
if (r < 0)
return r;
} else {
r = ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT);
if (r < 0)
return r;
}
break;
case IPV4LL_STATE_WAITING_PROBE:
case IPV4LL_STATE_PROBING:
/* Send a probe */
r = arp_send_probe(ll->fd, ll->index, ll->address, &ll->mac_addr);
if (r < 0) {
log_ipv4ll(ll, "Failed to send ARP probe.");
goto out;
}
if (ll->iteration < PROBE_NUM - 2) {
ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, false);
r = ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
if (r < 0)
goto out;
} else {
ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, true);
r = ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
if (r < 0)
goto out;
}
break;
case IPV4LL_STATE_ANNOUNCING:
if (ll->iteration >= ANNOUNCE_NUM - 1) {
ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, false);
break;
}
case IPV4LL_STATE_WAITING_ANNOUNCE:
/* Send announcement packet */
r = arp_send_announcement(ll->fd, ll->index, ll->address, &ll->mac_addr);
if (r < 0) {
log_ipv4ll(ll, "Failed to send ARP announcement.");
goto out;
}
ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, false);
r = ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
if (r < 0)
goto out;
if (ll->iteration == 0) {
log_ipv4ll(ll, "ANNOUNCE");
ll->claimed_address = ll->address;
ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND);
ll->conflict = 0;
}
break;
default:
assert_not_reached("Invalid state.");
}
out:
if (r < 0 && ll)
sd_ipv4ll_stop(ll);
return 1;
}
static int ipv4ll_on_conflict(sd_ipv4ll *ll) {
IPV4LL_DONT_DESTROY(ll);
int r;
assert(ll);
log_ipv4ll(ll, "CONFLICT");
ll->conflict++;
ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT);
sd_ipv4ll_stop(ll);
/* Pick a new address */
r = ipv4ll_pick_address(ll, &ll->address);
if (r < 0)
return r;
r = sd_ipv4ll_start(ll);
if (r < 0)
return r;
return 0;
}
static int ipv4ll_on_packet(sd_event_source *s, int fd,
uint32_t revents, void *userdata) {
sd_ipv4ll *ll = userdata;
struct ether_arp packet;
int r;
assert(ll);
assert(fd >= 0);
r = read(fd, &packet, sizeof(struct ether_arp));
if (r < (int) sizeof(struct ether_arp))
goto out;
switch (ll->state) {
case IPV4LL_STATE_ANNOUNCING:
case IPV4LL_STATE_RUNNING:
if (ipv4ll_arp_conflict(ll, &packet)) {
usec_t ts;
assert_se(sd_event_now(ll->event, clock_boottime_or_monotonic(), &ts) >= 0);
/* Defend address */
if (ts > ll->defend_window) {
ll->defend_window = ts + DEFEND_INTERVAL * USEC_PER_SEC;
r = arp_send_announcement(ll->fd, ll->index, ll->address, &ll->mac_addr);
if (r < 0) {
log_ipv4ll(ll, "Failed to send ARP announcement.");
goto out;
}
} else {
r = ipv4ll_on_conflict(ll);
if (r < 0)
goto out;
}
}
break;
case IPV4LL_STATE_WAITING_PROBE:
case IPV4LL_STATE_PROBING:
case IPV4LL_STATE_WAITING_ANNOUNCE:
/* BPF ensures this packet indicates a conflict */
r = ipv4ll_on_conflict(ll);
if (r < 0)
goto out;
break;
default:
assert_not_reached("Invalid state.");
}
out:
if (r < 0 && ll)
sd_ipv4ll_stop(ll);
return 1;
}
int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) {
assert_return(ll, -EINVAL);
assert_return(interface_index > 0, -EINVAL);
assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY);
ll->index = interface_index;
return 0;
}
int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
assert_return(ll, -EINVAL);
assert_return(addr, -EINVAL);
assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY);
if (memcmp(&ll->mac_addr, addr, ETH_ALEN) == 0)
return 0;
memcpy(&ll->mac_addr, addr, ETH_ALEN);
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)
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, false);
return ll->state != IPV4LL_STATE_INIT;
}
#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(ll->state == IPV4LL_STATE_INIT, -EBUSY);
ll->state = IPV4LL_STATE_INIT;
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;
}
r = arp_network_bind_raw_socket(ll->index, ll->address, &ll->mac_addr);
if (r < 0)
goto out;
safe_close(ll->fd);
ll->fd = r;
ipv4ll_set_state(ll, IPV4LL_STATE_INIT, true);
r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
EPOLLIN, ipv4ll_on_packet, 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 = ipv4ll_set_next_wakeup(ll, 0, 0);
if (r < 0)
goto out;
out:
if (r < 0)
ipv4ll_stop(ll);
return 0;
}