Howdy y'all,
I've noticed an interesting issue with udhcpd and auto_time.
Some paths within the while loop don't go through continue_with_autotime.
Thus, if it takes a bit too long to reset timeout_end, the monotonic
timer may be far enough along that the subtraction which sets tv.tv_sec
will overflow, like so:
Jan 21 19:38:13 10.0.0.1 udhcpd[75]: Waking from select()
Jan 21 19:38:13 10.0.0.1 udhcpd[75]: tv_sec = 10
Jan 21 19:38:21 10.0.0.1 udhcpd[75]: Waking from select()
Jan 21 19:38:23 10.0.0.1 udhcpd[75]: Sending OFFER of 10.0.0.2
Jan 21 19:38:23 10.0.0.1 udhcpd[75]: tv_sec = -1
Jan 21 19:38:23 10.0.0.1 udhcpd[75]: Waking from select()
Jan 21 19:38:23 10.0.0.1 udhcpd[75]: Sending ACK to 10.0.0.2
Jan 21 19:38:23 10.0.0.1 udhcpd[75]: tv_sec = -1
Jan 21 19:38:43 10.0.0.2 udhcpc[47]: Sending renew...
Jan 21 19:38:43 10.0.0.2 udhcpc[47]: Lease of 10.0.0.2 obtained, lease time 30
Jan 21 19:38:43 10.0.0.1 udhcpd[75]: Waking from select()
Jan 21 19:38:43 10.0.0.1 udhcpd[75]: Sending ACK to 10.0.0.2
Jan 21 19:38:43 10.0.0.1 udhcpd[75]: tv_sec = -21
Jan 21 19:39:03 10.0.0.2 udhcpc[47]: Sending renew...
Jan 21 19:39:03 10.0.0.1 udhcpd[75]: Waking from select()
Jan 21 19:39:03 10.0.0.1 udhcpd[75]: Sending ACK to 10.0.0.2
Jan 21 19:39:03 10.0.0.2 udhcpc[47]: Lease of 10.0.0.2 obtained, lease time 30
Jan 21 19:39:03 10.0.0.1 udhcpd[75]: tv_sec = -41
This patch adds a quick and easy check for it, resetting tv_sec to 0,
which should fall through to write_leases() and continue_with_autotime,
resetting timeout_end again.
Tim
---
networking/udhcp/dhcpd.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 4b3ed24..d56763f 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -415,6 +415,9 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv)
if (server_config.auto_time) {
tv.tv_sec = timeout_end - monotonic_sec();
tv.tv_usec = 0;
+
+ if ((unsigned)tv.tv_sec > server_config.auto_time)
+ tv.tv_sec = 0;
}
retval = 0;
if (!server_config.auto_time || tv.tv_sec > 0) {
--
2.0.4
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