#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 "arp-util.h"

#include "sd-ipv4ll.h"

#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__)

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 {

unsigned n_ref;

IPv4LLState state;

int index;

int fd;

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)

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)

return true;

return false;

}

static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) {

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 */

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;

}

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 */

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;

}

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 */

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, 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;

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

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->fd = safe_close(ll->fd);

r = arp_network_bind_raw_socket(ll->index, ll->address, &ll->mac_addr);

if (r < 0)

goto out;

ll->fd = r;

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 (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;

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, false);

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;

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, 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)

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 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);

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_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 = 1;

ll->state = IPV4LL_STATE_INIT;

ll->index = -1;

ll->fd = -1;

*ret = ll;

ll = NULL;

return 0;

}