Gives syslogd(8) the ability to refresh its idea of the hostname of

the system on which it is running. The hostname is reloaded when
'HUPped' and a log message generated to note a change (before anyone
points it out, this is not an added security feature).

PR:		bin/24444
Reviewed by:	freebsd-audit
Approved by:	ru
MFC after:	2 weeks

1 files changed, 27 insertions, 7 deletions

diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index 3866d73..d300c84 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -318,7 +318,7 @@ main(argc, argv)
 	struct sockaddr_un sunx, fromunix;
 	struct sockaddr_storage frominet;
 	FILE *fp;
-	char *p, *hname, line[MAXLINE + 1];
+	char *hname, line[MAXLINE + 1];
 	struct timeval tv, *tvp;
 	struct sigaction sact;
 	sigset_t mask;
@@ -398,12 +398,6 @@ main(argc, argv)
 
 	consfile.f_type = F_CONSOLE;
 	(void)strcpy(consfile.f_un.f_fname, ctty + sizeof _PATH_DEV - 1);
-	(void)gethostname(LocalHostName, sizeof(LocalHostName));
-	if ((p = strchr(LocalHostName, '.')) != NULL) {
-		*p++ = '\0';
-		LocalDomain = p;
-	} else
-		LocalDomain = "";
 	(void)strcpy(bootfile, getbootfile());
 	(void)signal(SIGTERM, die);
 	(void)signal(SIGINT, Debug ? die : SIG_IGN);
@@ -1346,10 +1340,26 @@ init(signo)
 	char cline[LINE_MAX];
  	char prog[NAME_MAX+1];
 	char host[MAXHOSTNAMELEN];
+	char oldLocalHostName[MAXHOSTNAMELEN];
+	char hostMsg[2*MAXHOSTNAMELEN+40];
 
 	dprintf("init\n");
 
 	/*
+	 * Load hostname (may have changed).
+	 */
+	if (signo != 0)
+		(void)strlcpy(oldLocalHostName, LocalHostName,
+		    sizeof(oldLocalHostName));
+	if (gethostname(LocalHostName, sizeof(LocalHostName)))
+		err(EX_OSERR, "gethostname() failed");
+	if ((p = strchr(LocalHostName, '.')) != NULL) {
+		*p++ = '\0';
+		LocalDomain = p;
+	} else
+		LocalDomain = "";
+
+	/*
 	 *  Close all open log files.
 	 */
 	Initialized = 0;
@@ -1498,6 +1508,16 @@ init(signo)
 
 	logmsg(LOG_SYSLOG|LOG_INFO, "syslogd: restart", LocalHostName, ADDDATE);
 	dprintf("syslogd: restarted\n");
+	/*
+	 * Log a change in hostname, but only on a restart.
+	 */
+	if (signo != 0 && strcmp(oldLocalHostName, LocalHostName) != 0) {
+		(void)snprintf(hostMsg, sizeof(hostMsg),
+		    "syslogd: hostname changed, \"%s\" to \"%s\"",
+		    oldLocalHostName, LocalHostName);
+		logmsg(LOG_SYSLOG|LOG_INFO, hostMsg, LocalHostName, ADDDATE);
+		dprintf("%s\n", hostMsg);
+	}
 }
 
 /*