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sd-radv: if lifetime < SD_RADV_DEFAULT_MAX_TIMEOUT_USEC, adjust timeout (#13491) 

The RFC states that lifetime (AdvDefaultLifetime) must be at least
MaxRtrAdvInterval (which more or less corresponds to SD_RADV_DEFAULT_MAX_TIMEOUT_USEC
in systemd).

To fulfill this limit, virtually lower MaxRtrAdvInterval and MinRtrAdvInterval
accordingly.

Also check that min is not lower than 3s and max is not lower than 4s.
This commit is contained in:
Georg Müller 2019-09-20 10:23:45 +02:00 committed by Frantisek Sumsal
parent 299d578f7f
commit ef90b6a4fb
1 changed files with 11 additions and 0 deletions
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11
src/libsystemd-network/sd-radv.c
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@ -273,6 +273,10 @@ static int radv_recv(sd_event_source *s, int fd, uint32_t revents, void *userdat
static usec_t radv_compute_timeout(usec_t min, usec_t max) {
assert_return(min <= max, SD_RADV_DEFAULT_MIN_TIMEOUT_USEC);
/* RFC 4861: min must be no less than 3s, max must be no less than 4s */
min = MAX(min, 3*USEC_PER_SEC);
max = MAX(max, 4*USEC_PER_SEC);
return min + (random_u32() % (max - min));
}
@ -302,6 +306,13 @@ static int radv_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
min_timeout = SD_RADV_MAX_INITIAL_RTR_ADVERT_INTERVAL_USEC / 3;
}
/* RFC 4861, Section 6.2.1, lifetime must be at least MaxRtrAdvInterval,
so lower the interval here */
if (ra->lifetime > 0 && (ra->lifetime * USEC_PER_SEC) < max_timeout) {
max_timeout = ra->lifetime * USEC_PER_SEC;
min_timeout = max_timeout / 3;
}
timeout = radv_compute_timeout(min_timeout, max_timeout);
log_radv("Next Router Advertisement in %s",