dhclient(8): fork_privchld, take_charge, propose_release: poll(2) -> ppoll(2)

Switch from poll(2) to ppoll(2) in a few more functions.

Because we're working with ppoll(2) and clock_gettime(2) it is easier
to encode the various timeouts as static const timespecs instead of
preprocessor macros.  This way we aren't packing timespecs in the
middle of the code, which distracts from the (more important) logic of
what the code is doing.

Part of a larger campaign improve "time stuff" in dhclient(8).

Prompted by and discussed with krw@.  Based on a diff by krw@.

ok krw@

1 files changed, 33 insertions, 30 deletions

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index 23fa185ec8c..8790a7f4be1 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.690 2020/12/10 18:35:31 krw Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.691 2021/02/02 15:46:16 cheloha Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -2367,11 +2367,11 @@ fork_privchld(struct interface_info *ifi, int fd, int fd2)
 		pfd[0].fd = priv_ibuf->fd;
 		pfd[0].events = POLLIN;
 
-		nfds = poll(pfd, 1, INFTIM);
+		nfds = ppoll(pfd, 1, NULL, NULL);
 		if (nfds == -1) {
 			if (errno == EINTR)
 				continue;
-			log_warn("%s: poll(priv_ibuf)", log_procname);
+			log_warn("%s: ppoll(priv_ibuf)", log_procname);
 			break;
 		}
 		if ((pfd[0].revents & (POLLERR | POLLHUP | POLLNVAL)) != 0)
@@ -2531,18 +2531,17 @@ cleanup:
 int
 take_charge(struct interface_info *ifi, int routefd, char *leasespath)
 {
+	const struct timespec	 max_timeout = { 9, 0 };
+	const struct timespec	 resend_intvl = { 3, 0 };
+	const struct timespec	 leasefile_intvl = { 0, 3000000 };
+	struct timespec		 now, resend, stop, timeout;
 	struct pollfd		 fds[1];
 	struct rt_msghdr	 rtm;
-	time_t			 cur_time, sent_time, start_time;
 	int			 fd, nfds;
 
-#define	MAXSECONDS		9
-#define	SENTSECONDS		3
-#define	POLLMILLISECONDS	3
-
-	if (time(&start_time) == -1)
-		fatal("time");
-	sent_time = start_time;
+	clock_gettime(CLOCK_REALTIME, &now);
+	resend = now;
+	timespecadd(&now, &max_timeout, &stop);
 
 	/*
 	 * Send RTM_PROPOSAL with RTF_PROTO3 set.
@@ -2561,32 +2560,35 @@ take_charge(struct interface_info *ifi, int routefd, char *leasespath)
 	rtm.rtm_addrs = 0;
 	rtm.rtm_flags = RTF_UP | RTF_PROTO3;
 
-	rtm.rtm_seq = ifi->xid = arc4random();
-	if (write(routefd, &rtm, sizeof(rtm)) == -1)
-		fatal("write(routefd)");
-
 	for (fd = -1; fd == -1 && quit != TERMINATE;) {
-		if (time(&cur_time) == -1)
-			fatal("time");
-		if (cur_time - start_time >= MAXSECONDS)
+		clock_gettime(CLOCK_REALTIME, &now);
+		if (timespeccmp(&now, &stop, >=))
 			fatalx("failed to take charge");
 
 		if ((ifi->flags & IFI_IN_CHARGE) == 0) {
-			if ((cur_time - sent_time) >= SENTSECONDS) {
-				sent_time = cur_time;
+			if (timespeccmp(&now, &resend, >=)) {
+				timespecadd(&resend, &resend_intvl, &resend);
 				rtm.rtm_seq = ifi->xid = arc4random();
 				if (write(routefd, &rtm, sizeof(rtm)) == -1)
 					fatal("write(routefd)");
 			}
+			timespecsub(&resend, &now, &timeout);
+		} else {
+			/*
+			 * Keep trying to open leasefile in 3ms intervals
+			 * while continuing to process any RTM_* messages
+			 * that come in.
+			 */
+			 timeout = leasefile_intvl;
 		}
 
 		fds[0].fd = routefd;
 		fds[0].events = POLLIN;
-		nfds = poll(fds, 1, POLLMILLISECONDS);
+		nfds = ppoll(fds, 1, &timeout, NULL);
 		if (nfds == -1) {
 			if (errno == EINTR)
 				continue;
-			fatal("poll(routefd)");
+			fatal("ppoll(routefd)");
 		}
 
 		if ((fds[0].revents & (POLLERR | POLLHUP | POLLNVAL)) != 0)
@@ -2801,13 +2803,14 @@ release_lease(struct interface_info *ifi)
 void
 propose_release(struct interface_info *ifi)
 {
+	const struct timespec	 max_timeout = { 3, 0 };
+	struct timespec		 now, stop, timeout;
 	struct pollfd		 fds[1];
 	struct rt_msghdr	 rtm;
-	time_t			 start_time, cur_time;
 	int			 nfds, routefd, rtfilter;
 
-	if (time(&start_time) == -1)
-		fatal("time");
+	clock_gettime(CLOCK_REALTIME, &now);
+	timespecadd(&now, &max_timeout, &stop);
 
 	if ((routefd = socket(AF_ROUTE, SOCK_RAW, AF_INET)) == -1)
 		fatal("socket(AF_ROUTE, SOCK_RAW)");
@@ -2838,17 +2841,17 @@ propose_release(struct interface_info *ifi)
 	log_debug("%s: sent RTM_PROPOSAL to release lease", log_procname);
 
 	while (quit == 0) {
-		if (time(&cur_time) == -1)
-			fatal("time");
-		if ((cur_time - start_time) > 3)
+		clock_gettime(CLOCK_REALTIME, &now);
+		if (timespeccmp(&now, &stop, >=))
 			break;
+		timespecsub(&stop, &now, &timeout);
 		fds[0].fd = routefd;
 		fds[0].events = POLLIN;
-		nfds = poll(fds, 1, 3);
+		nfds = ppoll(fds, 1, &timeout, NULL);
 		if (nfds == -1) {
 			if (errno == EINTR)
 				continue;
-			fatal("poll(routefd)");
+			fatal("ppoll(routefd)");
 		}
 		if ((fds[0].revents & (POLLERR | POLLHUP | POLLNVAL)) != 0)
 			fatalx("routefd: ERR|HUP|NVAL");