Make send_packet() usage consistent. i.e. don't exit

if send_packet(DISCOVER) fails.

Distinguish between writev() and sendmsg() errors in
send_packet() log messages.

Check for short writes no matter how the packet is
output. Return failure in this occurs. Check results
of all send_packet() calls.

If send_packet() fails, don't log that the DHCP message
was sent.

2 files changed, 36 insertions, 17 deletions

diff --git a/sbin/dhclient/bpf.c b/sbin/dhclient/bpf.c
index e1d7ce12ebc..6d57aa868ab 100644
--- a/sbin/dhclient/bpf.c
+++ b/sbin/dhclient/bpf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bpf.c,v 1.65 2017/09/17 21:20:23 krw Exp $	*/
+/*	$OpenBSD: bpf.c,v 1.66 2017/09/19 13:09:15 krw Exp $	*/
 
 /* BPF socket interface code, originally contributed by Archie Cobbs. */
 
@@ -249,7 +249,8 @@ send_packet(struct interface_info *ifi, struct in_addr from, struct in_addr to)
 	struct msghdr		 msg;
 	struct dhcp_packet	*packet = &ifi->sent_packet;
 	ssize_t			 result;
-	int			 iovcnt = 0, len = ifi->sent_packet_length;
+	unsigned int		 iovcnt = 0, i, total;
+	int			 len = ifi->sent_packet_length;
 
 	memset(&dest, 0, sizeof(dest));
 	dest.sin_family = AF_INET;
@@ -296,8 +297,19 @@ send_packet(struct interface_info *ifi, struct in_addr from, struct in_addr to)
 	iov[iovcnt].iov_len = len;
 	iovcnt++;
 
+	total = 0;
+	for (i = 0; i < iovcnt; i++)
+		total += iov[i].iov_len;
+
 	if (to.s_addr == INADDR_BROADCAST) {
 		result = writev(ifi->bfdesc, iov, iovcnt);
+		if (result == -1)
+			log_warn("%s: writev(bfdesc)", log_procname);
+		else if (result < total) {
+			result = -1;
+			log_warnx("%s, writev(bfdesc): %zd of %u bytes",
+			    log_procname, result, total);
+		}
 	} else {
 		memset(&msg, 0, sizeof(msg));
 		msg.msg_name = (struct sockaddr *)&dest;
@@ -305,10 +317,15 @@ send_packet(struct interface_info *ifi, struct in_addr from, struct in_addr to)
 		msg.msg_iov = iov;
 		msg.msg_iovlen = iovcnt;
 		result = sendmsg(ifi->ufdesc, &msg, 0);
+		if (result == -1)
+			log_warn("%s: sendmsg(ufdesc)", log_procname);
+		else if (result < total) {
+			result = -1;
+			log_warnx("%s, sendmsg(ufdesc): %zd of %u bytes",
+			    log_procname, result, total);
+		}
 	}
 
-	if (result == -1)
-		log_warn("%s: send_packet", log_procname);
 	return result;
 }
 
diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index a0fd214e456..d0f37017ba8 100644
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dhclient.c,v 1.503 2017/09/18 00:00:57 krw Exp $	*/
+/*	$OpenBSD: dhclient.c,v 1.504 2017/09/19 13:09:15 krw Exp $	*/
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -1334,15 +1334,13 @@ send_discover(struct interface_info *ifi)
 		packet->secs = htons(UINT16_MAX);
 	ifi->secs = packet->secs;
 
-	log_info("%s: DHCPDISCOVER - interval %lld", log_procname,
-	    (long long)ifi->interval);
 
 	rslt = send_packet(ifi, inaddr_any, inaddr_broadcast);
-	if (rslt == -1 && errno == EAFNOSUPPORT) {
-		log_warnx("%s: dhclient cannot be used", log_procname);
-		quit = INTERNALSIG;
-	} else
-		set_timeout(ifi, ifi->interval, send_discover);
+	if (rslt != -1)
+		log_info("%s: DHCPDISCOVER - interval %lld", log_procname,
+		    (long long)ifi->interval);
+
+	set_timeout(ifi, ifi->interval, send_discover);
 }
 
 /*
@@ -1377,6 +1375,7 @@ send_request(struct interface_info *ifi)
 	struct sockaddr_in	 destination;
 	struct in_addr		 from;
 	struct dhcp_packet	*packet = &ifi->sent_packet;
+	ssize_t			 rslt;
 	time_t			 cur_time;
 	int			 interval;
 
@@ -1466,10 +1465,11 @@ send_request(struct interface_info *ifi)
 			packet->secs = htons(UINT16_MAX);
 	}
 
-	log_info("%s: DHCPREQUEST to %s", log_procname,
-	    inet_ntoa(destination.sin_addr));
 
-	send_packet(ifi, from, destination.sin_addr);
+	rslt = send_packet(ifi, from, destination.sin_addr);
+	if (rslt != -1)
+		log_info("%s: DHCPREQUEST to %s", log_procname,
+		    inet_ntoa(destination.sin_addr));
 
 	set_timeout(ifi, ifi->interval, send_request);
 }
@@ -1477,9 +1477,11 @@ send_request(struct interface_info *ifi)
 void
 send_decline(struct interface_info *ifi)
 {
-	log_info("%s: DHCPDECLINE", log_procname);
+	ssize_t		rslt;
 
-	send_packet(ifi, inaddr_any, inaddr_broadcast);
+	rslt = send_packet(ifi, inaddr_any, inaddr_broadcast);
+	if (rslt != -1)
+		log_info("%s: DHCPDECLINE", log_procname);
 }
 
 void