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sd-radv: Implement Router Advertisement timeout handling 

Router Advertisements are sent uniformly distributed between a
minimum and maximum time according to RFC 4861, Section 6.2.4.
Default values from RFC 4861 are for now used as minimum and
maximum Router Advertisement timeouts.

When stopping, a Router Advertisement with a router lifetime set
to zero is sent in order to inform any nodes that the interface
on this host no longer is a router.
This commit is contained in:
Patrik Flykt 2017-05-12 16:48:34 +03:00
parent 7465dd22ad
commit 204fb681f6
2 changed files with 126 additions and 0 deletions
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13
src/libsystemd-network/radv-internal.h
View File

@ -25,6 +25,16 @@
#include "list.h"
#include "sparse-endian.h"
#define SD_RADV_DEFAULT_MIN_TIMEOUT_USEC (200*USEC_PER_SEC)
#define SD_RADV_DEFAULT_MAX_TIMEOUT_USEC (600*USEC_PER_SEC)
assert_cc(SD_RADV_DEFAULT_MIN_TIMEOUT_USEC <= SD_RADV_DEFAULT_MAX_TIMEOUT_USEC)
#define SD_RADV_MAX_INITIAL_RTR_ADVERT_INTERVAL_USEC (16*USEC_PER_SEC)
#define SD_RADV_MAX_INITIAL_RTR_ADVERTISEMENTS 3
#define SD_RADV_MAX_FINAL_RTR_ADVERTISEMENTS 3
#define SD_RADV_MIN_DELAY_BETWEEN_RAS 3
#define SD_RADV_MAX_RA_DELAY_TIME_USEC (500*USEC_PER_MSEC)
enum RAdvState {
SD_RADV_STATE_IDLE = 0,
SD_RADV_STATE_ADVERTISING = 1,
@ -46,6 +56,9 @@ struct sd_radv {
uint32_t mtu;
uint16_t lifetime;
unsigned ra_sent;
sd_event_source *timeout_event_source;
unsigned n_prefixes;
LIST_HEAD(sd_radv_prefix, prefixes);
};

113
src/libsystemd-network/sd-radv.c
View File

@ -32,6 +32,7 @@
#include "socket-util.h"
#include "string-util.h"
#include "util.h"
#include "random-util.h"
_public_ int sd_radv_new(sd_radv **ret) {
_cleanup_(sd_radv_unrefp) sd_radv *ra = NULL;
@ -85,6 +86,14 @@ _public_ sd_event *sd_radv_get_event(sd_radv *ra) {
return ra->event;
}
static void radv_reset(sd_radv *ra) {
ra->timeout_event_source =
sd_event_source_unref(ra->timeout_event_source);
ra->ra_sent = 0;
}
_public_ sd_radv *sd_radv_ref(sd_radv *ra) {
if (!ra)
return NULL;
@ -112,21 +121,106 @@ _public_ sd_radv *sd_radv_unref(sd_radv *ra) {
sd_radv_prefix_unref(p);
}
radv_reset(ra);
sd_radv_detach_event(ra);
return mfree(ra);
}
static int radv_send(sd_radv *ra, const struct in6_addr *dst,
const uint32_t router_lifetime) {
return -ENOSYS;
}
static usec_t radv_compute_timeout(usec_t min, usec_t max) {
assert_return(min <= max, SD_RADV_DEFAULT_MIN_TIMEOUT_USEC);
return min + (random_u32() % (max - min));
}
static int radv_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
int r;
sd_radv *ra = userdata;
usec_t min_timeout = SD_RADV_DEFAULT_MIN_TIMEOUT_USEC;
usec_t max_timeout = SD_RADV_DEFAULT_MAX_TIMEOUT_USEC;
usec_t time_now, timeout;
char time_string[FORMAT_TIMESPAN_MAX];
assert(s);
assert(ra);
assert(ra->event);
ra->timeout_event_source = sd_event_source_unref(ra->timeout_event_source);
r = sd_event_now(ra->event, clock_boottime_or_monotonic(), &time_now);
if (r < 0)
goto fail;
r = radv_send(ra, NULL, ra->lifetime);
if (r < 0)
log_radv_warning_errno(r, "Unable to send Router Advertisement: %m");
/* RFC 4861, Section 6.2.4, sending initial Router Advertisements */
if (ra->ra_sent < SD_RADV_MAX_INITIAL_RTR_ADVERTISEMENTS) {
max_timeout = SD_RADV_MAX_INITIAL_RTR_ADVERT_INTERVAL_USEC;
min_timeout = SD_RADV_MAX_INITIAL_RTR_ADVERT_INTERVAL_USEC / 3;
}
timeout = radv_compute_timeout(min_timeout, max_timeout);
log_radv("Next Router Advertisement in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX,
timeout, USEC_PER_SEC));
r = sd_event_add_time(ra->event, &ra->timeout_event_source,
clock_boottime_or_monotonic(),
time_now + timeout, MSEC_PER_SEC,
radv_timeout, ra);
if (r < 0)
goto fail;
r = sd_event_source_set_priority(ra->timeout_event_source,
ra->event_priority);
if (r < 0)
goto fail;
r = sd_event_source_set_description(ra->timeout_event_source,
"radv-timeout");
if (r < 0)
goto fail;
ra->ra_sent++;
fail:
if (r < 0)
sd_radv_stop(ra);
return 0;
}
_public_ int sd_radv_stop(sd_radv *ra) {
int r;
assert_return(ra, -EINVAL);
log_radv("Stopping IPv6 Router Advertisement daemon");
/* RFC 4861, Section 6.2.5, send at least one Router Advertisement
with zero lifetime */
r = radv_send(ra, NULL, 0);
if (r < 0)
log_radv_warning_errno(r, "Unable to send last Router Advertisement with router lifetime set to zero: %m");
radv_reset(ra);
ra->state = SD_RADV_STATE_IDLE;
return 0;
}
_public_ int sd_radv_start(sd_radv *ra) {
int r = 0;
assert_return(ra, -EINVAL);
assert_return(ra->event, -EINVAL);
assert_return(ra->ifindex > 0, -EINVAL);
@ -134,11 +228,30 @@ _public_ int sd_radv_start(sd_radv *ra) {
if (ra->state != SD_RADV_STATE_IDLE)
return 0;
r = sd_event_add_time(ra->event, &ra->timeout_event_source,
clock_boottime_or_monotonic(), 0, 0,
radv_timeout, ra);
if (r < 0)
goto fail;
r = sd_event_source_set_priority(ra->timeout_event_source,
ra->event_priority);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(ra->timeout_event_source,
"radv-timeout");
ra->state = SD_RADV_STATE_ADVERTISING;
log_radv("Started IPv6 Router Advertisement daemon");
return 0;
fail:
radv_reset(ra);
return r;
}
_public_ int sd_radv_set_ifindex(sd_radv *ra, int ifindex) {