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dhcp: Add patch to avoid IP address changes during runtime 

Whenever there's a big time jump due to an outaded RTC being updated via NTP,
detect the jump and update the DHCP lease's expiry times accordingly.

https://jira.digi.com/browse/DEL-5233

Signed-off-by: Gabriel Valcazar <gabriel.valcazar@digi.com>
This commit is contained in:
Gabriel Valcazar 2018-03-05 10:40:50 +01:00
parent e3d086c472
commit 73b3c2e255
2 changed files with 76 additions and 1 deletions
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72
meta-digi-dey/recipes-connectivity/dhcp/dhcp/0002-dhclient-Check-if-the-rebind-time-has-expired-when-r.patch Normal file
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@ -0,0 +1,72 @@
From: Gabriel Valcazar <gabriel.valcazar@digi.com>
Date: Mon, 5 Mar 2018 10:00:23 +0100
Subject: [PATCH] dhclient: Check if the rebind time has expired when renewing
the lease
If the system time suffers a big jump, the client will start the renewal
process but it will end prematurely due to the expiry of the lease time. By
adding this check, a time jump can be detected and the active lease can be
updated with the correct expiry dates.
https://jira.digi.com/browse/DEL-5233
Signed-off-by: Gabriel Valcazar <gabriel.valcazar@digi.com>
---
client/dhclient.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/client/dhclient.c b/client/dhclient.c
index dcf3f1a..9074373 100644
--- a/client/dhclient.c
+++ b/client/dhclient.c
@@ -101,6 +101,8 @@ char *mockup_relay = NULL;
char *progname = NULL;
+TIME time_of_binding;
+
void run_stateless(int exit_mode, u_int16_t port);
static isc_result_t write_duid(struct data_string *duid);
@@ -1440,6 +1442,9 @@ void bind_lease (client)
client->active = client->new;
client->new = NULL;
+ /* Save the time at which the binding occurred. */
+ time_of_binding = cur_time;
+
/* Set up a timeout to start the renewal process. */
tv.tv_sec = client->active->renewal;
tv.tv_usec = ((client->active->renewal - cur_tv.tv_sec) > 1) ?
@@ -1472,6 +1477,30 @@ void state_bound (cpp)
ASSERT_STATE(state, S_BOUND);
+ /*
+ * The T2 lease time for the active lease should never be expired when
+ * reaching this state. If so, it means there has been a time jump in
+ * the system's clock. In this case, update the lease with the correct
+ * times and create a new state_bound timeout.
+ */
+ if (cur_time > client->active->rebind) {
+ struct timeval tv;
+
+ TIME time_jump = cur_time - time_of_binding;
+ client->active->renewal += time_jump;
+ client->active->rebind += time_jump;
+ client->active->expiry += time_jump;
+
+ rewrite_client_leases();
+
+ /* Set up a timeout to start the renewal process. */
+ tv.tv_sec = client->active->renewal;
+ tv.tv_usec = ((client->active->renewal - cur_tv.tv_sec) > 1) ?
+ random() % 1000000 : cur_tv.tv_usec;
+ add_timeout(&tv, state_bound, client, 0, 0);
+ return;
+ }
+
/* T1 has expired. */
make_request (client, client -> active);
client -> xid = client -> packet.xid;

5
meta-digi-dey/recipes-connectivity/dhcp/dhcp_4.3.6.bbappend
View File

@ -2,4 +2,7 @@
FILESEXTRAPATHS_prepend := "${THISDIR}/${BPN}:"
SRC_URI += " file://0001-keep-resolv.conf-rights.patch"
SRC_URI += " \
file://0001-keep-resolv.conf-rights.patch \
file://0002-dhclient-Check-if-the-rebind-time-has-expired-when-r.patch \
"