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dhcp: don't underflow in lease time calculations

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Don't underflow when calculating lease time.
This commit is contained in:
Lennart Poettering 2015-08-27 01:59:43 +02:00
parent 586ac6f711
commit fbcd420aa4
1 changed files with 11 additions and 7 deletions
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18
src/libsystemd-network/sd-dhcp-client.c
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@ -1163,13 +1163,17 @@ static int client_handle_ack(sd_dhcp_client *client, DHCPMessage *ack,
return r;
}
static uint64_t client_compute_timeout(sd_dhcp_client *client,
uint32_t lifetime, double factor) {
static uint64_t client_compute_timeout(sd_dhcp_client *client, uint32_t lifetime, double factor) {
assert(client);
assert(client->request_sent);
assert(lifetime);
assert(lifetime > 0);
return client->request_sent + ((lifetime - 3) * USEC_PER_SEC * factor) +
if (lifetime > 3)
lifetime -= 3;
else
lifetime = 0;
return client->request_sent + (lifetime * USEC_PER_SEC * factor) +
+ (random_u32() & 0x1fffff);
}
@ -1201,7 +1205,7 @@ static int client_set_lease_timeouts(sd_dhcp_client *client) {
/* convert the various timeouts from relative (secs) to absolute (usecs) */
lifetime_timeout = client_compute_timeout(client, client->lease->lifetime, 1);
if (client->lease->t1 && client->lease->t2) {
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) {
@ -1215,7 +1219,7 @@ static int client_set_lease_timeouts(sd_dhcp_client *client) {
t1_timeout = client_compute_timeout(client, client->lease->lifetime, 0.5);
client->lease->t1 = client->lease->lifetime / 2;
}
} else if (client->lease->t2 && client->lease->t2 < client->lease->lifetime) {
} 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);
@ -1225,7 +1229,7 @@ static int client_set_lease_timeouts(sd_dhcp_client *client) {
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 && client->lease->t1 < client->lease->lifetime) {
} 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);