dns: T5144: Improve dynamic DNS validations and completions

Apply validations and completions to dynamic DNS protocols supported.
This also opens up additional protocols supported by ddclient 3.10.

Additional details:
- Validation and constraint have been added for interface names as well.
- While at it, the help texts got some copyedit and rewording.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/validators/ddclient-protocol b/src/validators/ddclient-protocol
new file mode 100755
index 000000000..6f927927b
--- /dev/null
+++ b/src/validators/ddclient-protocol
@@ -0,0 +1,24 @@
+#!/bin/sh
+#
+# Copyright (C) 2023 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# 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, see <http://www.gnu.org/licenses/>.
+
+ddclient -list-protocols | grep -qw $1
+
+if [ $? -gt 0 ]; then
+    echo "Error: $1 is not a valid protocol, please choose from the supported list of protocols"
+    exit 1
+fi
+
+exit 0