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Merge pull request #17908 from ddstreet/dhcpv4_rfc2131_intervals

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Fix dhcpv4 renew/rebind intervals to match rfc2131
This commit is contained in:
Yu Watanabe 2020-12-16 05:05:06 +09:00 committed by GitHub
commit 3a23834d6b
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2 changed files with 80 additions and 88 deletions
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164
src/libsystemd-network/sd-dhcp-client.c
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@ -29,6 +29,7 @@
#include "sort-util.h"
#include "string-util.h"
#include "strv.h"
#include "time-util.h"
#include "utf8.h"
#include "web-util.h"
@ -98,6 +99,9 @@ struct sd_dhcp_client {
uint32_t fallback_lease_lifetime;
uint32_t xid;
usec_t start_time;
usec_t t1_time;
usec_t t2_time;
usec_t expire_time;
uint64_t attempt;
uint64_t max_attempts;
OrderedHashmap *extra_options;
@ -727,6 +731,37 @@ static void client_stop(sd_dhcp_client *client, int error) {
client_initialize(client);
}
/* RFC2131 section 4.1:
* retransmission delays should include -1 to +1 sec of random 'fuzz'. */
#define RFC2131_RANDOM_FUZZ \
((int64_t)(random_u64() % (2 * USEC_PER_SEC)) - (int64_t)USEC_PER_SEC)
/* RFC2131 section 4.1:
* for retransmission delays, timeout should start at 4s then double
* each attempt with max of 64s, with -1 to +1 sec of random 'fuzz' added.
* This assumes the first call will be using attempt 1. */
static usec_t client_compute_request_timeout(usec_t now, uint64_t attempt) {
usec_t timeout = (UINT64_C(1) << MIN(attempt + 1, UINT64_C(6))) * USEC_PER_SEC;
return usec_sub_signed(usec_add(now, timeout), RFC2131_RANDOM_FUZZ);
}
/* RFC2131 section 4.4.5:
* T1 defaults to (0.5 * duration_of_lease).
* T2 defaults to (0.875 * duration_of_lease). */
#define T1_DEFAULT(lifetime) ((lifetime) / 2)
#define T2_DEFAULT(lifetime) (((lifetime) * 7) / 8)
/* RFC2131 section 4.4.5:
* the client SHOULD wait one-half of the remaining time until T2 (in RENEWING state)
* and one-half of the remaining lease time (in REBINDING state), down to a minimum
* of 60 seconds.
* Note that while the default T1/T2 initial times do have random 'fuzz' applied,
* the RFC sec 4.4.5 does not mention adding any fuzz to retries. */
static usec_t client_compute_reacquisition_timeout(usec_t now, usec_t expire) {
return MAX(usec_sub_unsigned(expire, now) / 2, 60 * USEC_PER_SEC);
}
static int cmp_uint8(const uint8_t *a, const uint8_t *b) {
return CMP(*a, *b);
}
@ -1192,7 +1227,6 @@ static int client_timeout_resend(
DHCP_CLIENT_DONT_DESTROY(client);
usec_t next_timeout;
uint64_t time_now;
uint32_t time_left;
int r;
assert(s);
@ -1206,19 +1240,11 @@ static int client_timeout_resend(
switch (client->state) {
case DHCP_STATE_RENEWING:
time_left = (client->lease->t2 - client->lease->t1) / 2;
if (time_left < 60)
time_left = 60;
next_timeout = time_now + time_left * USEC_PER_SEC;
next_timeout = client_compute_reacquisition_timeout(time_now, client->t2_time);
break;
case DHCP_STATE_REBINDING:
time_left = (client->lease->lifetime - client->lease->t2) / 2;
if (time_left < 60)
time_left = 60;
next_timeout = time_now + time_left * USEC_PER_SEC;
next_timeout = client_compute_reacquisition_timeout(time_now, client->expire_time);
break;
case DHCP_STATE_REBOOTING:
@ -1243,7 +1269,7 @@ static int client_timeout_resend(
goto error;
client->attempt++;
next_timeout = time_now + ((UINT64_C(1) << MIN(client->attempt, (uint64_t) 6)) - 1) * USEC_PER_SEC;
next_timeout = client_compute_request_timeout(time_now, client->attempt);
break;
case DHCP_STATE_STOPPED:
@ -1251,8 +1277,6 @@ static int client_timeout_resend(
goto error;
}
next_timeout += (random_u32() & 0x1fffff);
r = event_reset_time(client->event, &client->timeout_resend,
clock_boottime_or_monotonic(),
next_timeout, 10 * USEC_PER_MSEC,
@ -1618,25 +1642,8 @@ static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack, size_t le
return r;
}
static uint64_t client_compute_timeout(sd_dhcp_client *client, uint32_t lifetime, double factor) {
assert(client);
assert(client->request_sent);
assert(lifetime > 0);
if (lifetime > 3)
lifetime -= 3;
else
lifetime = 0;
return client->request_sent + (lifetime * USEC_PER_SEC * factor) +
+ (random_u32() & 0x1fffff);
}
static int client_set_lease_timeouts(sd_dhcp_client *client) {
usec_t time_now;
uint64_t lifetime_timeout;
uint64_t t2_timeout;
uint64_t t1_timeout;
char time_string[FORMAT_TIMESPAN_MAX];
int r;
@ -1659,93 +1666,76 @@ static int client_set_lease_timeouts(sd_dhcp_client *client) {
return r;
assert(client->request_sent <= time_now);
/* convert the various timeouts from relative (secs) to absolute (usecs) */
lifetime_timeout = client_compute_timeout(client, client->lease->lifetime, 1);
if (client->lease->t1 > 0 && client->lease->t2 > 0) {
/* both T1 and T2 are given */
if (client->lease->t1 < client->lease->t2 &&
client->lease->t2 < client->lease->lifetime) {
/* they are both valid */
t2_timeout = client_compute_timeout(client, client->lease->t2, 1);
t1_timeout = client_compute_timeout(client, client->lease->t1, 1);
} else {
/* discard both */
t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
client->lease->t2 = (client->lease->lifetime * 7) / 8;
t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
client->lease->t1 = client->lease->lifetime / 2;
}
} else if (client->lease->t2 > 0 && client->lease->t2 < client->lease->lifetime) {
/* only T2 is given, and it is valid */
t2_timeout = client_compute_timeout(client, client->lease->t2, 1);
t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
client->lease->t1 = client->lease->lifetime / 2;
if (t2_timeout <= t1_timeout) {
/* the computed T1 would be invalid, so discard T2 */
t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
client->lease->t2 = (client->lease->lifetime * 7) / 8;
}
} else if (client->lease->t1 > 0 && client->lease->t1 < client->lease->lifetime) {
/* only T1 is given, and it is valid */
t1_timeout = client_compute_timeout(client, client->lease->t1, 1);
t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
client->lease->t2 = (client->lease->lifetime * 7) / 8;
if (t2_timeout <= t1_timeout) {
/* the computed T2 would be invalid, so discard T1 */
t2_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
client->lease->t2 = client->lease->lifetime / 2;
}
} else {
/* fall back to the default timeouts */
t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
client->lease->t1 = client->lease->lifetime / 2;
t2_timeout = client_compute_timeout(client, client->lease->lifetime, 7.0 / 8.0);
client->lease->t2 = (client->lease->lifetime * 7) / 8;
}
/* verify that 0 < t2 < lifetime */
if (client->lease->t2 == 0 || client->lease->t2 >= client->lease->lifetime)
client->lease->t2 = T2_DEFAULT(client->lease->lifetime);
/* verify that 0 < t1 < lifetime */
if (client->lease->t1 == 0 || client->lease->t1 >= client->lease->t2)
client->lease->t1 = T1_DEFAULT(client->lease->lifetime);
/* now, if t1 >= t2, t1 *must* be T1_DEFAULT, since the previous check
* could not evalate to false if t1 >= t2; so setting t2 to T2_DEFAULT
* guarantees t1 < t2. */
if (client->lease->t1 >= client->lease->t2)
client->lease->t2 = T2_DEFAULT(client->lease->lifetime);
client->expire_time = client->request_sent + client->lease->lifetime * USEC_PER_SEC;
client->t1_time = client->request_sent + client->lease->t1 * USEC_PER_SEC;
client->t2_time = client->request_sent + client->lease->t2 * USEC_PER_SEC;
/* RFC2131 section 4.4.5:
* Times T1 and T2 SHOULD be chosen with some random "fuzz".
* Since the RFC doesn't specify here the exact 'fuzz' to use,
* we use the range from section 4.1: -1 to +1 sec. */
client->t1_time = usec_sub_signed(client->t1_time, RFC2131_RANDOM_FUZZ);
client->t2_time = usec_sub_signed(client->t2_time, RFC2131_RANDOM_FUZZ);
/* after fuzzing, ensure t2 is still >= t1 */
client->t2_time = MAX(client->t1_time, client->t2_time);
/* arm lifetime timeout */
r = event_reset_time(client->event, &client->timeout_expire,
clock_boottime_or_monotonic(),
lifetime_timeout, 10 * USEC_PER_MSEC,
client->expire_time, 10 * USEC_PER_MSEC,
client_timeout_expire, client,
client->event_priority, "dhcp4-lifetime", true);
if (r < 0)
return r;
log_dhcp_client(client, "lease expires in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX, lifetime_timeout - time_now, USEC_PER_SEC));
/* don't arm earlier timeouts if this has already expired */
if (lifetime_timeout <= time_now)
if (client->expire_time <= time_now)
return 0;
log_dhcp_client(client, "lease expires in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX, client->expire_time - time_now, USEC_PER_SEC));
/* arm T2 timeout */
r = event_reset_time(client->event, &client->timeout_t2,
clock_boottime_or_monotonic(),
t2_timeout, 10 * USEC_PER_MSEC,
client->t2_time, 10 * USEC_PER_MSEC,
client_timeout_t2, client,
client->event_priority, "dhcp4-t2-timeout", true);
if (r < 0)
return r;
log_dhcp_client(client, "T2 expires in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX, t2_timeout - time_now, USEC_PER_SEC));
/* don't arm earlier timeout if this has already expired */
if (t2_timeout <= time_now)
if (client->t2_time <= time_now)
return 0;
log_dhcp_client(client, "T2 expires in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX, client->t2_time - time_now, USEC_PER_SEC));
/* arm T1 timeout */
r = event_reset_time(client->event, &client->timeout_t1,
clock_boottime_or_monotonic(),
t1_timeout, 10 * USEC_PER_MSEC,
client->t1_time, 10 * USEC_PER_MSEC,
client_timeout_t1, client,
client->event_priority, "dhcp4-t1-timer", true);
if (r < 0)
return r;
log_dhcp_client(client, "T1 expires in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX, t1_timeout - time_now, USEC_PER_SEC));
if (client->t1_time > time_now)
log_dhcp_client(client, "T1 expires in %s",
format_timespan(time_string, FORMAT_TIMESPAN_MAX, client->t1_time - time_now, USEC_PER_SEC));
return 0;
}

4
test/test-network/systemd-networkd-tests.py
View File

@ -4104,7 +4104,9 @@ class NetworkdDHCPClientTests(unittest.TestCase, Utilities):
copy_unit_to_networkd_unit_path('25-veth.netdev', 'dhcp-server-veth-peer.network',
'dhcp-client-with-ipv4ll.network')
start_networkd()
self.wait_online(['veth99:degraded', 'veth-peer:routable'])
# we need to increase timeout above default, as this will need to wait for
# systemd-networkd to get the dhcpv4 transient failure event
self.wait_online(['veth99:degraded', 'veth-peer:routable'], timeout='60s')
output = check_output('ip address show dev veth99')
print(output)