This patch adds a method to manage the resource limit which was
introduced by the fix for ISC-Bugs #41845. This patch was developed
in-house. ISC did not express any interest in incorporating this patch
into their code since they consider the limit to be a mitigating
solution.

diff -r 1680283c6725 includes/omapip/omapip.h
--- a/includes/omapip/omapip.h	Tue Jan 16 13:35:26 2018 -0800
+++ b/includes/omapip/omapip.h	Tue Jan 16 18:01:14 2018 -0800
@@ -467,6 +467,9 @@
 
 extern omapi_object_type_t *omapi_object_types;
 
+#if defined (sun)
+void omapi_set_max_fd_value (void);
+#endif
 void omapi_type_relinquish (void);
 isc_result_t omapi_init (void);
 isc_result_t omapi_object_type_register (omapi_object_type_t **,
diff -r 1680283c6725 omapip/listener.c
--- a/omapip/listener.c	Tue Jan 16 13:35:26 2018 -0800
+++ b/omapip/listener.c	Tue Jan 16 18:01:14 2018 -0800
@@ -40,6 +40,10 @@
 trace_type_t *trace_listener_accept;
 #endif
 
+#if defined (sun)
+static int conn_limit = MAX_FD_VALUE; /* max number of open sockets allowed */
+#endif
+
 OMAPI_OBJECT_ALLOC (omapi_listener,
 		    omapi_listener_object_t, omapi_type_listener)
 
@@ -209,6 +213,35 @@
 	return l -> socket;
 }
 
+#if defined (sun)
+/* If OMAPI_CONN_LIMIT environment variable is set, obtain value. */
+const char *fname = "omapi_set_max_fd_value";
+void omapi_set_max_fd_value (void)
+{
+	const char *env;
+	char *end = NULL;
+	int envval = conn_limit;
+
+	env = getenv("OMAPI_CONN_LIMIT");
+	if (env != NULL) {
+		errno = 0;
+		envval = (int)strtol(env, &end, 10);
+		if (errno != 0 || env == end || *end != '\0' || envval < 0) {
+			(void) log_error("%s: \"%s\" is not a valid connection "
+					"limit value\n", fname, env);
+			errno = 0;
+		} else {
+			conn_limit = envval;
+		}
+	}
+	(void) log_debug("%s: conn_limit = %d%s\n", fname, conn_limit,
+			(conn_limit == MAX_FD_VALUE) ? " (default)" :
+			(conn_limit == 0) ? " (unlimited)" : "");
+
+	return;
+}
+#endif
+
 /* Reader callback for a listener object.   Accept an incoming connection. */
 isc_result_t omapi_accept (omapi_object_t *h)
 {
@@ -233,7 +266,13 @@
 		return ISC_R_UNEXPECTED;
 	}
 
+#if !defined (sun)
 	if ((MAX_FD_VALUE != 0) && (socket > MAX_FD_VALUE)) {
+#else
+	if ((conn_limit != 0) && (socket > conn_limit)) {
+		(void) log_debug("omapi_accept: No more available "
+		    "sockets - closing latest.\n");
+#endif
 		close(socket);
 		return (ISC_R_NORESOURCES);
 	}
diff -r 1680283c6725 server/dhcpd.c
--- a/server/dhcpd.c	Tue Jan 16 13:35:26 2018 -0800
+++ b/server/dhcpd.c	Tue Jan 16 18:01:14 2018 -0800
@@ -452,6 +452,10 @@
 		path_dhcpd_conf = s;
 	}
 
+#if defined (sun)
+	omapi_set_max_fd_value ();
+#endif
+
 #ifdef DHCPv6
         if (local_family == AF_INET6) {
                 /* DHCPv6: override DHCPv4 lease and pid filenames */