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authorLennart Poettering <lennart@poettering.net>2015-08-27 01:59:43 +0200
committerLennart Poettering <lennart@poettering.net>2015-08-27 01:59:43 +0200
commitfbcd420aa407dc3c16efd9fb32cbae6d04d4f65d (patch)
tree1fef6dd487d0aa4f2abe5541a5ba7a77c9d66186 /src/libsystemd-network
parent586ac6f711e2eccceb12421df22fca4f117226c4 (diff)
dhcp: don't underflow in lease time calculations
Don't underflow when calculating lease time.
Diffstat (limited to 'src/libsystemd-network')
-rw-r--r--src/libsystemd-network/sd-dhcp-client.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 008b21c3b8..c12768cf0e 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -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);