Switch dispatch loop to ppoll() and protocol timeouts to struct timespec.

Reduces spurious packet transmissions in situations with short timings.

Suggestions millert@, further suggestions & ok cheloha@

diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index b964413..023af04 100644 (file)
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dhcpd.h,v 1.290 2020/12/10 18:35:32 krw Exp $ */
+/*     $OpenBSD: dhcpd.h,v 1.291 2021/02/01 01:42:20 krw Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -135,7 +135,7 @@ struct interface_info {
        struct dhcp_packet       sent_packet;
        int                      sent_packet_length;
        uint32_t                 xid;
-       time_t                   timeout;
+       struct timespec          timeout;
        time_t                   expiry, rebind;
        void                    (*timeout_func)(struct interface_info *);
        uint16_t                 secs;

diff --git a/sbin/dhclient/dispatch.c b/sbin/dhclient/dispatch.c
index 93c0249..a32c5e4 100644 (file)
--- a/sbin/dhclient/dispatch.c
+++ b/sbin/dhclient/dispatch.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dispatch.c,v 1.166 2019/11/19 14:35:08 krw Exp $      */
+/*     $OpenBSD: dispatch.c,v 1.167 2021/02/01 01:42:21 krw Exp $      */
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -84,9 +84,10 @@ void
 dispatch(struct interface_info *ifi, int routefd)
 {
        struct pollfd            fds[3];
+       struct timespec          timeout;
+       struct timespec         *ts;
        void                    (*func)(struct interface_info *);
-       time_t                   cur_time, howlong;
-       int                      nfds, to_msec;
+       int                      nfds;
 
        while (quit == 0 || quit == RESTART) {
                if (quit == RESTART) {
@@ -99,26 +100,18 @@ dispatch(struct interface_info *ifi, int routefd)
                        ifi->state = S_PREBOOT;
                        state_preboot(ifi);
                }
-               if (ifi->timeout_func != NULL) {
-                       time(&cur_time);
-                       if (ifi->timeout <= cur_time) {
+               if (timespecisset(&ifi->timeout)) {
+                       clock_gettime(CLOCK_REALTIME, &timeout);
+                       if (timespeccmp(&timeout, &ifi->timeout, >=)) {
                                func = ifi->timeout_func;
                                cancel_timeout(ifi);
                                (*(func))(ifi);
                                continue;
                        }
-                       /*
-                        * Figure timeout in milliseconds, and check for
-                        * potential overflow, so we can cram into an
-                        * int for poll, while not polling with a
-                        * negative timeout and blocking indefinitely.
-                        */
-                       howlong = ifi->timeout - cur_time;
-                       if (howlong > INT_MAX / 1000)
-                               howlong = INT_MAX / 1000;
-                       to_msec = howlong * 1000;
+                       timespecsub(&ifi->timeout, &timeout, &timeout);
+                       ts = &timeout;
                } else
-                       to_msec = -1;
+                       ts = NULL;
 
                /*
                 * Set up the descriptors to be polled.
@@ -135,7 +128,7 @@ dispatch(struct interface_info *ifi, int routefd)
                if (unpriv_ibuf->w.queued)
                        fds[2].events |= POLLOUT;
 
-               nfds = poll(fds, 3, to_msec);
+               nfds = ppoll(fds, 3, ts, NULL);
                if (nfds == -1) {
                        if (errno == EINTR)
                                continue;
@@ -307,15 +300,18 @@ void
 set_timeout(struct interface_info *ifi, time_t secs,
     void (*where)(struct interface_info *))
 {
-       time(&ifi->timeout);
-       if (secs > 0)
-               ifi->timeout += secs;
+       struct timespec         cur_time;
+
+       clock_gettime(CLOCK_REALTIME, &cur_time);
+       timespecclear(&ifi->timeout);
+       ifi->timeout.tv_sec = secs;
+       timespecadd(&ifi->timeout, &cur_time, &ifi->timeout);
        ifi->timeout_func = where;
 }
 
 void
 cancel_timeout(struct interface_info *ifi)
 {
-       ifi->timeout = 0;
+       timespecclear(&ifi->timeout);
        ifi->timeout_func = NULL;
 }