bfdd: session specific command type checks

Replace the unclear error message:

```
% Failed to edit configuration.

YANG error(s):
 Schema node not found.
 YANG path: /frr-bfdd:bfdd/bfd/sessions/single-hop[dest-addr='192.168.253.6'][interface=''][vrf='default']/minimum-ttl
```

With:

```
frr(config-bfd-peer)# minimum-ttl 250
% Minimum TTL is only available for multi hop sessions.

! or

frr(config-bfd-peer)# echo
% Echo mode is only available for single hop sessions.
frr(config-bfd-peer)# echo-interval 300
% Echo mode is only available for single hop sessions.
```

Reported-by: Trae Santiago
Signed-off-by: Rafael Zalamena <rzalamena@opensourcerouting.org>

diff --git a/bfdd/bfdd_cli.c b/bfdd/bfdd_cli.c
index ddec83397dd2d87f4780815769c5cddc1d89dff6..b9e7903613f0228f5c455d437193b305901264d1 100644 (file)
--- a/bfdd/bfdd_cli.c
+++ b/bfdd/bfdd_cli.c
@@ -51,6 +51,11 @@
 /*
  * Prototypes.
  */
+static bool
+bfd_cli_is_single_hop(struct vty *vty)
+{
+       return strstr(VTY_CURR_XPATH, "/single-hop") != NULL;
+}
 
 /*
  * Functions.
@@ -293,6 +298,11 @@ DEFPY_YANG(
        "Expect packets with at least this TTL\n"
        "Minimum TTL expected\n")
 {
+       if (bfd_cli_is_single_hop(vty)) {
+               vty_out(vty, "%% Minimum TTL is only available for multi hop sessions.\n");
+               return CMD_WARNING_CONFIG_FAILED;
+       }
+
        if (no)
                nb_cli_enqueue_change(vty, "./minimum-ttl", NB_OP_DESTROY,
                                      NULL);
@@ -408,6 +418,11 @@ DEFPY_YANG(
        NO_STR
        "Configure echo mode\n")
 {
+       if (!bfd_cli_is_single_hop(vty)) {
+               vty_out(vty, "%% Echo mode is only available for single hop sessions.\n");
+               return CMD_WARNING_CONFIG_FAILED;
+       }
+
        nb_cli_enqueue_change(vty, "./echo-mode", NB_OP_MODIFY,
                              no ? "false" : "true");
        return nb_cli_apply_changes(vty, NULL);
@@ -431,6 +446,11 @@ DEFPY_YANG(
 {
        char value[32];
 
+       if (!bfd_cli_is_single_hop(vty)) {
+               vty_out(vty, "%% Echo mode is only available for single hop sessions.\n");
+               return CMD_WARNING_CONFIG_FAILED;
+       }
+
        snprintf(value, sizeof(value), "%ld", interval * 1000);
        nb_cli_enqueue_change(vty, "./desired-echo-transmission-interval",
                              NB_OP_MODIFY, value);