lib: Support auto completion of configured keychain.

Problem Statement:
=================
When modules use keychain there is no option for auto completion
of configured keychains.

RCA:
====
Not implemented.

Fix:
====
Changes to support auto completion of configured keychain names.

Risk:
=====
Low risk

Tests Executed:
===============
Have tested auto completion of configured keychain names with newly
implemented auth CLI.

frr(config-if)# ipv6 ospf6 authentication keychain
  KEYCHAIN_NAME  Keychain name
     abcd pqr 12345

Signed-off-by: Abhinay Ramesh <rabhinay@vmware.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/keychain.c b/lib/keychain.c
index 02f83ef0a..1d678b949 100644
--- a/lib/keychain.c
+++ b/lib/keychain.c
@@ -1051,10 +1051,28 @@ static int keychain_config_write(struct vty *vty)
 	return 0;
 }
 
+static void keychain_active_config(vector comps, struct cmd_token *token)
+{
+	struct keychain *keychain;
+	struct listnode *node;
+
+	for (ALL_LIST_ELEMENTS_RO(keychain_list, node, keychain))
+		vector_set(comps, XSTRDUP(MTYPE_COMPLETION, keychain->name));
+}
+
+static const struct cmd_variable_handler keychain_var_handlers[] = {
+	{.varname = "key_chain", .completions = keychain_active_config},
+	{.tokenname = "KEYCHAIN_NAME", .completions = keychain_active_config},
+	{.tokenname = "KCHAIN_NAME", .completions = keychain_active_config},
+	{.completions = NULL}
+};
+
 void keychain_init(void)
 {
 	keychain_list = list_new();
 
+	/* Register handler for keychain auto config support */
+	cmd_variable_handler_register(keychain_var_handlers);
 	install_node(&keychain_node);
 	install_node(&keychain_key_node);