git: c8c624de57b0 - stable/13 - dhclient: Keep two clocks
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Date: Wed, 23 Apr 2025 04:51:00 UTC
The branch stable/13 has been updated by cperciva:
URL: https://cgit.FreeBSD.org/src/commit/?id=c8c624de57b072d14c1ab23167880a069ef51f11
commit c8c624de57b072d14c1ab23167880a069ef51f11
Author: Colin Percival <cperciva@FreeBSD.org>
AuthorDate: 2025-04-08 22:50:01 +0000
Commit: Colin Percival <cperciva@FreeBSD.org>
CommitDate: 2025-04-23 04:50:55 +0000
dhclient: Keep two clocks
Until July 2024, dhclient kept track of time as seconds-since-epoch as
a time_t. This was a problem because (a) we wanted sub-second timeouts
and (b) timeouts didn't always do the right thing if the system clock
changed.
Switching to using CLOCK_MONOTONIC and struct timespec fixed those
issues but introduced a new problem: CLOCK_MONOTONIC values were being
intepreted as seconds-since-epoch and written to the dhclient.leases
file, causing confusion with DHCP leases expiring in early 1970.
Attempt to compromise between these by keeping track of both times;
any type within dhclient which is a time_t now refers to seconds past
the epoch, while any struct timespec value is a CLOCK_MONOTONIC time.
PR: 283256
Reviewed by: dch
Fixes: f0a38976b01e ("dhclient: Use clock_gettime() instead of time()")
Sponsored by: Amazon
Differential Revision: https://reviews.freebsd.org/D49720
(cherry picked from commit 43d19e6a4c42ade0f276ceca18a09e2e3829fce4)
---
sbin/dhclient/dhclient.c | 50 +++++++++++++++++++++---------------------------
sbin/dhclient/dhcpd.h | 4 ++--
sbin/dhclient/dispatch.c | 14 +++++++++-----
3 files changed, 33 insertions(+), 35 deletions(-)
diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index 141403d8c86b..0ac2a493a94f 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -90,8 +90,8 @@
cap_channel_t *capsyslog;
-time_t cur_time;
-struct timespec time_now;
+time_t cur_time; /* Seconds since epoch. */
+struct timespec time_now; /* CLOCK_MONOTONIC. */
static time_t default_lease_time = 43200; /* 12 hours... */
const char *path_dhclient_conf = _PATH_DHCLIENT_CONF;
@@ -450,7 +450,7 @@ main(int argc, char *argv[])
tzset();
clock_gettime(CLOCK_MONOTONIC, &time_now);
- cur_time = time_now.tv_sec;
+ cur_time = time(NULL);
inaddr_broadcast.s_addr = INADDR_BROADCAST;
inaddr_any.s_addr = INADDR_ANY;
@@ -1030,13 +1030,13 @@ dhcpoffer(struct packet *packet)
struct client_lease *lease, *lp;
int i;
struct timespec arp_timeout_needed;
- struct timespec stop_selecting = { .tv_sec = 0, .tv_nsec = 0 };
- time_now.tv_sec = cur_time;
- time_now.tv_nsec = 0;
-
+ time_t stop_selecting;
+ struct timespec stop_time;
const char *name = packet->options[DHO_DHCP_MESSAGE_TYPE].len ?
"DHCPOFFER" : "BOOTREPLY";
+ clock_gettime(CLOCK_MONOTONIC, &time_now);
+
/* If we're not receptive to an offer right now, or if the offer
has an unrecognizable transaction id, then just drop it. */
if (ip->client->state != S_SELECTING ||
@@ -1096,7 +1096,7 @@ dhcpoffer(struct packet *packet)
arp_timeout_needed = arp_timeout;
/* Figure out when we're supposed to stop selecting. */
- stop_selecting.tv_sec =
+ stop_selecting =
ip->client->first_sending + ip->client->config->select_interval;
/* If this is the lease we asked for, put it at the head of the
@@ -1117,7 +1117,7 @@ dhcpoffer(struct packet *packet)
timespecadd(&time_now, &arp_timeout_needed, &interm_struct);
if (ip->client->offered_leases &&
- timespeccmp(&interm_struct, &stop_selecting, >))
+ interm_struct.tv_sec >= stop_selecting)
arp_timeout_needed = zero_timespec;
/* Put the lease at the end of the list. */
@@ -1132,27 +1132,21 @@ dhcpoffer(struct packet *packet)
}
}
- /* If we're supposed to stop selecting before we've had time
- to wait for the ARPREPLY, add some delay to wait for
- the ARPREPLY. */
- struct timespec time_left;
- timespecsub(&stop_selecting, &time_now, &time_left);
-
+ /*
+ * Wait until stop_selecting seconds past the epoch, or until
+ * arp_timeout_needed past now, whichever is longer. Note that
+ * the first case only occurs if select-timeout is set to nonzero
+ * in dhclient.conf.
+ */
+ struct timespec time_left =
+ {.tv_sec = stop_selecting - cur_time, .tv_nsec = 0};
if (timespeccmp(&time_left, &arp_timeout_needed, <)) {
- timespecadd(&time_now, &arp_timeout_needed, &stop_selecting);
- }
-
- /* If the selecting interval has expired, go immediately to
- state_selecting(). Otherwise, time out into
- state_selecting at the select interval. */
-
-
- if (timespeccmp(&stop_selecting, &zero_timespec, <=))
- state_selecting(ip);
- else {
- add_timeout_timespec(stop_selecting, state_selecting, ip);
- cancel_timeout(send_discover, ip);
+ timespecadd(&time_now, &arp_timeout_needed, &stop_time);
+ } else {
+ timespecadd(&time_now, &time_left, &stop_time);
}
+ add_timeout_timespec(stop_time, state_selecting, ip);
+ cancel_timeout(send_discover, ip);
}
/* Allocate a client_lease structure and initialize it from the parameters
diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index abe652c06fec..13c748c3f83f 100644
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -361,8 +361,8 @@ char *piaddr(struct iaddr);
extern cap_channel_t *capsyslog;
extern const char *path_dhclient_conf;
extern char *path_dhclient_db;
-extern struct timespec time_now;
-extern time_t cur_time;
+extern struct timespec time_now; /* CLOCK_MONOTONIC */
+extern time_t cur_time; /* Seconds since epoch */
extern int log_priority;
extern int log_perror;
diff --git a/sbin/dhclient/dispatch.c b/sbin/dhclient/dispatch.c
index 78d94804468b..bfa96b391bf8 100644
--- a/sbin/dhclient/dispatch.c
+++ b/sbin/dhclient/dispatch.c
@@ -171,8 +171,8 @@ dispatch(void)
struct protocol *l;
struct pollfd *fds;
struct timespec howlong;
- time_now.tv_sec = cur_time;
- time_now.tv_nsec = 0;
+
+ clock_gettime(CLOCK_MONOTONIC, &time_now);
for (l = protocols; l; l = l->next)
nfds++;
@@ -236,7 +236,7 @@ another:
if (count == -1) {
if (errno == EAGAIN || errno == EINTR) {
clock_gettime(CLOCK_MONOTONIC, &time_now);
- cur_time = time_now.tv_sec;
+ cur_time = time(NULL);
continue;
} else
error("poll: %m");
@@ -244,7 +244,7 @@ another:
/* Get the current time... */
clock_gettime(CLOCK_MONOTONIC, &time_now);
- cur_time = time_now.tv_sec;
+ cur_time = time(NULL);
i = 0;
for (l = protocols; l; l = l->next) {
@@ -377,7 +377,11 @@ active:
void
add_timeout(time_t when_s, void (*where)(void *), void *what)
{
- struct timespec when = { .tv_sec = when_s, .tv_nsec = 0 };
+ struct timespec when;
+
+ cur_time = time(NULL);
+ clock_gettime(CLOCK_MONOTONIC, &when);
+ when.tv_sec += when_s - cur_time;
add_timeout_timespec(when, where, what);
}