When DNS lookup of an UDP loghost failed, syslogd(8) did close the

UDP sockets for sending messages.  Keep the sockets open if the
config allows to send UDP.  Then they can be used to send if DNS
is working during the next SIGHUP.
bug reported and fix tested by sven falempin; OK millert@

1 files changed, 24 insertions, 19 deletions

diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index be63e9403c8..bbdce6b7c2e 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: syslogd.c,v 1.262 2019/07/05 13:23:27 bluhm Exp $	*/
+/*	$OpenBSD: syslogd.c,v 1.263 2020/05/25 10:38:32 bluhm Exp $	*/
 
 /*
  * Copyright (c) 2014-2017 Alexander Bluhm <bluhm@genua.de>
@@ -853,20 +853,6 @@ main(int argc, char *argv[])
 			event_add(ev_udp, NULL);
 		if (fd_udp6 != -1)
 			event_add(ev_udp6, NULL);
-	} else {
-		/*
-		 * If generic UDP file descriptors are used neither
-		 * for receiving nor for sending, close them.  Then
-		 * there is no useless *.514 in netstat.
-		 */
-		if (fd_udp != -1 && !send_udp) {
-			close(fd_udp);
-			fd_udp = -1;
-		}
-		if (fd_udp6 != -1 && !send_udp6) {
-			close(fd_udp6);
-			fd_udp6 = -1;
-		}
 	}
 	for (i = 0; i < nbind; i++)
 		if (fd_bind[i] != -1)
@@ -2416,6 +2402,7 @@ init(void)
 	s = 0;
 	strlcpy(progblock, "*", sizeof(progblock));
 	strlcpy(hostblock, "*", sizeof(hostblock));
+	send_udp = send_udp6 = 0;
 	while (getline(&cline, &s, cf) != -1) {
 		/*
 		 * check for end-of-section, comments, strip off trailing
@@ -2508,6 +2495,22 @@ init(void)
 	Initialized = 1;
 	dropped_warn(&init_dropped, "during initialization");
 
+	if (SecureMode) {
+		/*
+		 * If generic UDP file descriptors are used neither
+		 * for receiving nor for sending, close them.  Then
+		 * there is no useless *.514 in netstat.
+		 */
+		if (fd_udp != -1 && !send_udp) {
+			close(fd_udp);
+			fd_udp = -1;
+		}
+		if (fd_udp6 != -1 && !send_udp6) {
+			close(fd_udp6);
+			fd_udp6 = -1;
+		}
+	}
+
 	if (Debug) {
 		SIMPLEQ_FOREACH(f, &Files, f_next) {
 			for (i = 0; i <= LOG_NFACILITIES; i++)
@@ -2704,20 +2707,24 @@ cfline(char *line, char *progblock, char *hostblock)
 		}
 		if (proto == NULL)
 			proto = "udp";
-		ipproto = proto;
 		if (strcmp(proto, "udp") == 0) {
 			if (fd_udp == -1)
 				proto = "udp6";
 			if (fd_udp6 == -1)
 				proto = "udp4";
-			ipproto = proto;
+		}
+		ipproto = proto;
+		if (strcmp(proto, "udp") == 0) {
+			send_udp = send_udp6 = 1;
 		} else if (strcmp(proto, "udp4") == 0) {
+			send_udp = 1;
 			if (fd_udp == -1) {
 				log_warnx("no udp4 \"%s\"",
 				    f->f_un.f_forw.f_loghost);
 				break;
 			}
 		} else if (strcmp(proto, "udp6") == 0) {
+			send_udp6 = 1;
 			if (fd_udp6 == -1) {
 				log_warnx("no udp6 \"%s\"",
 				    f->f_un.f_forw.f_loghost);
@@ -2761,11 +2768,9 @@ cfline(char *line, char *progblock, char *hostblock)
 		if (strncmp(proto, "udp", 3) == 0) {
 			switch (f->f_un.f_forw.f_addr.ss_family) {
 			case AF_INET:
-				send_udp = 1;
 				f->f_file = fd_udp;
 				break;
 			case AF_INET6:
-				send_udp6 = 1;
 				f->f_file = fd_udp6;
 				break;
 			}