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Systemd/src/libsystemd-network/sd-ipv4acd.c
Lennart Poettering 4afd3348c7 tree-wide: expose "p"-suffix unref calls in public APIs to make gcc cleanup easy 
GLIB has recently started to officially support the gcc cleanup
attribute in its public API, hence let's do the same for our APIs.

With this patch we'll define an xyz_unrefp() call for each public
xyz_unref() call, to make it easy to use inside a
__attribute__((cleanup())) expression. Then, all code is ported over to
make use of this.

The new calls are also documented in the man pages, with examples how to
use them (well, I only added docs where the _unref() call itself already
had docs, and the examples, only cover sd_bus_unrefp() and
sd_event_unrefp()).

This also renames sd_lldp_free() to sd_lldp_unref(), since that's how we
tend to call our destructors these days.

Note that this defines no public macro that wraps gcc's attribute and
makes it easier to use. While I think it's our duty in the library to
make our stuff easy to use, I figure it's not our duty to make gcc's own
features easy to use on its own. Most likely, client code which wants to
make use of this should define its own:

       #define _cleanup_(function) __attribute__((cleanup(function)))

Or similar, to make the gcc feature easier to use.

Making this logic public has the benefit that we can remove three header
files whose only purpose was to define these functions internally.

See #2008.
2015-11-27 19:19:36 +01:00

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/***
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 <arpa/inet.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "sd-ipv4acd.h"
#include "alloc-util.h"
#include "arp-util.h"
#include "fd-util.h"
#include "in-addr-util.h"
#include "list.h"
#include "random-util.h"
#include "refcnt.h"
#include "siphash24.h"
#include "util.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 IPV4ACD_NETWORK 0xA9FE0000L
#define IPV4ACD_NETMASK 0xFFFF0000L
#define log_ipv4acd_full(ll, level, error, fmt, ...) log_internal(level, error, __FILE__, __LINE__, __func__, "ACD: " fmt, ##__VA_ARGS__)
#define log_ipv4acd_debug(ll, ...) log_ipv4acd_full(ll, LOG_DEBUG, 0, ##__VA_ARGS__)
#define log_ipv4acd_info(ll, ...) log_ipv4acd_full(ll, LOG_INFO, 0, ##__VA_ARGS__)
#define log_ipv4acd_notice(ll, ...) log_ipv4acd_full(ll, LOG_NOTICE, 0, ##__VA_ARGS__)
#define log_ipv4acd_warning(ll, ...) log_ipv4acd_full(ll, LOG_WARNING, 0, ##__VA_ARGS__)
#define log_ipv4acd_error(ll, ...) log_ipv4acd_full(ll, LOG_ERR, 0, ##__VA_ARGS__)
#define log_ipv4acd_debug_errno(ll, error, ...) log_ipv4acd_full(ll, LOG_DEBUG, error, ##__VA_ARGS__)
#define log_ipv4acd_info_errno(ll, error, ...) log_ipv4acd_full(ll, LOG_INFO, error, ##__VA_ARGS__)
#define log_ipv4acd_notice_errno(ll, error, ...) log_ipv4acd_full(ll, LOG_NOTICE, error, ##__VA_ARGS__)
#define log_ipv4acd_warning_errno(ll, error, ...) log_ipv4acd_full(ll, LOG_WARNING, error, ##__VA_ARGS__)
#define log_ipv4acd_error_errno(ll, error, ...) log_ipv4acd_full(ll, LOG_ERR, error, ##__VA_ARGS__)
typedef enum IPv4ACDState {
IPV4ACD_STATE_INIT,
IPV4ACD_STATE_WAITING_PROBE,
IPV4ACD_STATE_PROBING,
IPV4ACD_STATE_WAITING_ANNOUNCE,
IPV4ACD_STATE_ANNOUNCING,
IPV4ACD_STATE_RUNNING,
_IPV4ACD_STATE_MAX,
_IPV4ACD_STATE_INVALID = -1
} IPv4ACDState;
struct sd_ipv4acd {
RefCount n_ref;
IPv4ACDState 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;
/* External */
struct ether_addr mac_addr;
sd_event *event;
int event_priority;
sd_ipv4acd_cb_t cb;
void* userdata;
};
sd_ipv4acd *sd_ipv4acd_ref(sd_ipv4acd *ll) {
if (ll)
assert_se(REFCNT_INC(ll->n_ref) >= 2);
return ll;
}
sd_ipv4acd *sd_ipv4acd_unref(sd_ipv4acd *ll) {
if (!ll || REFCNT_DEC(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_ipv4acd_detach_event(ll);
free(ll);
return NULL;
}
int sd_ipv4acd_new(sd_ipv4acd **ret) {
_cleanup_(sd_ipv4acd_unrefp) sd_ipv4acd *ll = NULL;
assert_return(ret, -EINVAL);
ll = new0(sd_ipv4acd, 1);
if (!ll)
return -ENOMEM;
ll->n_ref = REFCNT_INIT;
ll->state = IPV4ACD_STATE_INIT;
ll->index = -1;
ll->fd = -1;
*ret = ll;
ll = NULL;
return 0;
}
static void ipv4acd_set_state(sd_ipv4acd *ll, IPv4ACDState st, bool reset_counter) {
assert(ll);
assert(st < _IPV4ACD_STATE_MAX);
if (st == ll->state && !reset_counter)
ll->iteration++;
else {
ll->state = st;
ll->iteration = 0;
}
}
static void ipv4acd_client_notify(sd_ipv4acd *ll, int event) {
assert(ll);
if (ll->cb)
ll->cb(ll, event, ll->userdata);
}
static void ipv4acd_stop(sd_ipv4acd *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_ipv4acd_debug(ll, "STOPPED");
ipv4acd_set_state (ll, IPV4ACD_STATE_INIT, true);
}
int sd_ipv4acd_stop(sd_ipv4acd *ll) {
assert_return(ll, -EINVAL);
ipv4acd_stop(ll);
ipv4acd_client_notify(ll, SD_IPV4ACD_EVENT_STOP);
return 0;
}
static int ipv4acd_on_timeout(sd_event_source *s, uint64_t usec, void *userdata);
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 ipv4acd_arp_conflict(sd_ipv4acd *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 ipv4acd_on_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
sd_ipv4acd *ll = userdata;
int r = 0;
assert(ll);
switch (ll->state) {
case IPV4ACD_STATE_INIT:
ipv4acd_set_state(ll, IPV4ACD_STATE_WAITING_PROBE, true);
if (ll->conflict >= MAX_CONFLICTS) {
log_ipv4acd_notice(ll, "Max conflicts reached, delaying by %us", RATE_LIMIT_INTERVAL);
r = ipv4acd_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT);
if (r < 0)
goto out;
ll->conflict = 0;
} else {
r = ipv4acd_set_next_wakeup(ll, 0, PROBE_WAIT);
if (r < 0)
goto out;
}
break;
case IPV4ACD_STATE_WAITING_PROBE:
case IPV4ACD_STATE_PROBING:
/* Send a probe */
r = arp_send_probe(ll->fd, ll->index, ll->address, &ll->mac_addr);
if (r < 0) {
log_ipv4acd_error_errno(ll, r, "Failed to send ARP probe: %m");
goto out;
} else {
_cleanup_free_ char *address = NULL;
union in_addr_union addr = { .in.s_addr = ll->address };
r = in_addr_to_string(AF_INET, &addr, &address);
if (r >= 0)
log_ipv4acd_debug(ll, "Probing %s", address);
}
if (ll->iteration < PROBE_NUM - 2) {
ipv4acd_set_state(ll, IPV4ACD_STATE_PROBING, false);
r = ipv4acd_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN));
if (r < 0)
goto out;
} else {
ipv4acd_set_state(ll, IPV4ACD_STATE_WAITING_ANNOUNCE, true);
r = ipv4acd_set_next_wakeup(ll, ANNOUNCE_WAIT, 0);
if (r < 0)
goto out;
}
break;
case IPV4ACD_STATE_ANNOUNCING:
if (ll->iteration >= ANNOUNCE_NUM - 1) {
ipv4acd_set_state(ll, IPV4ACD_STATE_RUNNING, false);
break;
}
case IPV4ACD_STATE_WAITING_ANNOUNCE:
/* Send announcement packet */
r = arp_send_announcement(ll->fd, ll->index, ll->address, &ll->mac_addr);
if (r < 0) {
log_ipv4acd_error_errno(ll, r, "Failed to send ARP announcement: %m");
goto out;
} else
log_ipv4acd_debug(ll, "ANNOUNCE");
ipv4acd_set_state(ll, IPV4ACD_STATE_ANNOUNCING, false);
r = ipv4acd_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0);
if (r < 0)
goto out;
if (ll->iteration == 0) {
ll->conflict = 0;
ipv4acd_client_notify(ll, SD_IPV4ACD_EVENT_BIND);
}
break;
default:
assert_not_reached("Invalid state.");
}
out:
if (r < 0)
sd_ipv4acd_stop(ll);
return 1;
}
static void ipv4acd_on_conflict(sd_ipv4acd *ll) {
_cleanup_free_ char *address = NULL;
union in_addr_union addr = { .in.s_addr = ll->address };
int r;
assert(ll);
ll->conflict++;
r = in_addr_to_string(AF_INET, &addr, &address);
if (r >= 0)
log_ipv4acd_debug(ll, "Conflict on %s (%u)", address, ll->conflict);
ipv4acd_stop(ll);
ipv4acd_client_notify(ll, SD_IPV4ACD_EVENT_CONFLICT);
}
static int ipv4acd_on_packet(sd_event_source *s, int fd,
uint32_t revents, void *userdata) {
sd_ipv4acd *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 IPV4ACD_STATE_ANNOUNCING:
case IPV4ACD_STATE_RUNNING:
if (ipv4acd_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_ipv4acd_error_errno(ll, r, "Failed to send ARP announcement: %m");
goto out;
} else
log_ipv4acd_debug(ll, "DEFEND");
} else
ipv4acd_on_conflict(ll);
}
break;
case IPV4ACD_STATE_WAITING_PROBE:
case IPV4ACD_STATE_PROBING:
case IPV4ACD_STATE_WAITING_ANNOUNCE:
/* BPF ensures this packet indicates a conflict */
ipv4acd_on_conflict(ll);
break;
default:
assert_not_reached("Invalid state.");
}
out:
if (r < 0)
sd_ipv4acd_stop(ll);
return 1;
}
int sd_ipv4acd_set_index(sd_ipv4acd *ll, int interface_index) {
assert_return(ll, -EINVAL);
assert_return(interface_index > 0, -EINVAL);
assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
ll->index = interface_index;
return 0;
}
int sd_ipv4acd_set_mac(sd_ipv4acd *ll, const struct ether_addr *addr) {
assert_return(ll, -EINVAL);
assert_return(addr, -EINVAL);
assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
memcpy(&ll->mac_addr, addr, ETH_ALEN);
return 0;
}
int sd_ipv4acd_detach_event(sd_ipv4acd *ll) {
assert_return(ll, -EINVAL);
ll->event = sd_event_unref(ll->event);
return 0;
}
int sd_ipv4acd_attach_event(sd_ipv4acd *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_ipv4acd_set_callback(sd_ipv4acd *ll, sd_ipv4acd_cb_t cb, void *userdata) {
assert_return(ll, -EINVAL);
ll->cb = cb;
ll->userdata = userdata;
return 0;
}
int sd_ipv4acd_set_address(sd_ipv4acd *ll, const struct in_addr *address){
assert_return(ll, -EINVAL);
assert_return(address, -EINVAL);
assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
ll->address = address->s_addr;
return 0;
}
int sd_ipv4acd_is_running(sd_ipv4acd *ll) {
assert_return(ll, false);
return ll->state != IPV4ACD_STATE_INIT;
}
static bool ether_addr_is_nul(const struct ether_addr *addr) {
const struct ether_addr nul_addr = {};
assert(addr);
return memcmp(addr, &nul_addr, sizeof(struct ether_addr)) == 0;
}
#define HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
int sd_ipv4acd_start(sd_ipv4acd *ll) {
int r;
assert_return(ll, -EINVAL);
assert_return(ll->event, -EINVAL);
assert_return(ll->index > 0, -EINVAL);
assert_return(ll->address != 0, -EINVAL);
assert_return(!ether_addr_is_nul(&ll->mac_addr), -EINVAL);
assert_return(ll->state == IPV4ACD_STATE_INIT, -EBUSY);
ll->defend_window = 0;
r = arp_network_bind_raw_socket(ll->index, ll->address, &ll->mac_addr);
if (r < 0)
goto out;
ll->fd = safe_close(ll->fd);
ll->fd = r;
r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd,
EPOLLIN, ipv4acd_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, "ipv4acd-receive-message");
if (r < 0)
goto out;
r = ipv4acd_set_next_wakeup(ll, 0, 0);
if (r < 0)
goto out;
out:
if (r < 0) {
ipv4acd_stop(ll);
return r;
}
return 0;
}
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