networkd: clean up vlan handling a bit (#3478)

Let's add a generic parser for VLAN ids, which should become handy as
preparation for PR #3428. Let's also make sure we use uint16_t for the vlan ID
type everywhere, and that validity checks are already applied at the time of
parsing, and not only whne we about to prepare a netdev.

Also, establish a common definition VLANID_INVALID we can use for
non-initialized VLAN id fields.

1 files changed, 35 insertions, 0 deletions

diff --git a/src/shared/vlan-util.h b/src/shared/vlan-util.h
new file mode 100644
index 0000000000..ce6763b3a3
--- /dev/null
+++ b/src/shared/vlan-util.h
@@ -0,0 +1,35 @@
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdbool.h>
+#include <inttypes.h>
+
+#define VLANID_MAX 4094
+#define VLANID_INVALID UINT16_MAX
+
+/* Note that we permit VLAN Id 0 here, as that is apparently OK by the Linux kernel */
+static inline bool vlanid_is_valid(uint16_t id) {
+        return id <= VLANID_MAX;
+}
+
+int parse_vlanid(const char *p, uint16_t *ret);
+
+int config_parse_vlanid(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);