1 files changed, 77 insertions, 0 deletions
diff --git a/src/dnsmasq-manager/nm-dnsmasq-utils.c b/src/dnsmasq-manager/nm-dnsmasq-utils.c
new file mode 100644
index 00000000..7036b409
--- /dev/null
+++ b/src/dnsmasq-manager/nm-dnsmasq-utils.c
@@ -0,0 +1,77 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/* NetworkManager -- Network link manager
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Copyright (C) 2013 Red Hat, Inc.
+ */
+
+#include <config.h>
+#include <string.h>
+#include <arpa/inet.h>
+
+#include "nm-dnsmasq-utils.h"
+#include "nm-platform.h"
+#include "nm-utils.h"
+
+gboolean
+nm_dnsmasq_utils_get_range (const NMPlatformIP4Address *addr,
+                            char *out_first,
+                            char *out_last,
+                            char **out_error_desc)
+{
+	guint32 host = addr->address;
+	guint32 prefix = addr->plen;
+	guint32 netmask = nm_utils_ip4_prefix_to_netmask (prefix);
+	guint32 first, last, reserved;
+
+	g_return_val_if_fail (out_first != NULL, FALSE);
+	g_return_val_if_fail (out_last != NULL, FALSE);
+
+	if (prefix > 30) {
+		if (out_error_desc)
+			*out_error_desc = g_strdup_printf ("Address prefix %d is too small for DHCP.", prefix);
+		return FALSE;
+	}
+
+	/* Find the first available address *after* the local machine's IP */
+	first = (host & netmask) + htonl (1);
+
+	/* Shortcut: allow a max of 253 addresses; the - htonl(1) here is to assure
+	 * that we don't set 'last' to the broadcast address of the network. */
+	if (prefix < 24)
+		last = (host | ~nm_utils_ip4_prefix_to_netmask (24)) - htonl (1);
+	else
+		last = (host | ~netmask) - htonl(1);
+
+	/* Figure out which range (either above the host address or below it)
+	 * has more addresses.  Reserve some addresses for static IPs.
+	 */
+	if (ntohl (host) - ntohl (first) > ntohl (last) - ntohl (host)) {
+		/* Range below the host's IP address */
+		reserved = (guint32) ((ntohl (host) - ntohl (first)) / 10);
+		last = host - htonl (MIN (reserved, 8)) - htonl (1);
+	} else {
+		/* Range above host's IP address */
+		reserved = (guint32) ((ntohl (last) - ntohl (host)) / 10);
+		first = host + htonl (MIN (reserved, 8)) + htonl (1);
+	}
+
+	nm_utils_inet4_ntop (first, out_first);
+	nm_utils_inet4_ntop (last, out_last);
+
+	return TRUE;
+}
+