isisd: fix 'show isis route prefix-sid backup' command

It is not possible to dump both backup and prefix-sid
information. Fix this by authorising it.

> rt1# show isis route prefix-sid backup
> Area 1:
> IS-IS paths to level-1 routers that speak IP
> Vertex               Type         Metric Next-Hop             Interface Parent
> rt1
> 10.12.0.0/24         IP internal  0                                     rt1(4)
> 10.13.0.0/24         IP internal  0                                     rt1(4)
> 1.1.1.1/32           IP internal  0                                     rt1(4)
> rt2                  TE-IS        10     rt2                  eth-rt2   rt1(4)
> rt3                  TE-IS        10     rt3                  eth-rt3   rt1(4)
> 10.12.0.0/24         IP TE        20     rt2                  eth-rt2   rt2(4)
> 10.23.0.0/24         IP TE        20     rt2                  eth-rt2   rt2(4)
>                                          rt3                  eth-rt3   rt3(4)
> 2.2.2.2/32           IP TE        20     rt2                  eth-rt2   rt2(4)
> 10.13.0.0/24         IP TE        20     rt3                  eth-rt3   rt3(4)
> 3.3.3.3/32           IP TE        20     rt3                  eth-rt3   rt3(4)
>
> IS-IS L1 IPv4 routing table:
>
> IS-IS paths to level-1 routers that speak IPv6
> Vertex               Type         Metric Next-Hop             Interface Parent
> rt1
> 2001:db8:1000::1/128 IP6 internal 0                                     rt1(4)
> rt2                  TE-IS        10     rt2                  eth-rt2   rt1(4)
> rt3                  TE-IS        10     rt3                  eth-rt3   rt1(4)
> 2001:db8:1000::2/128 IP6 internal 20     rt2                  eth-rt2   rt2(4)
> 2001:db8:1000::3/128 IP6 internal 20     rt3                  eth-rt3   rt3(4)
>
> IS-IS L1 IPv6 routing table:
>

Fixes: d47d608 ("isisd: refactor handling of SR Prefix-SIDs")

Signed-off-by: Philippe Guibert <[email protected]>

Author: pguibert6WIND

doc/user/isisd.rst

@@ -325,7 +325,7 @@ Showing ISIS information
    Show topology IS-IS paths to Intermediate Systems, globally, in area
    (level-1) or domain (level-2).
 
-.. clicmd:: show isis [vrf <NAME|all>] route [level-1|level-2] [prefix-sid|backup] [algorithm [(128-255)]]
+.. clicmd:: show isis [vrf <NAME|all>] route [level-1|level-2] <prefix-sid|backup> [algorithm [(128-255)]]
 
    Show the ISIS routing table, as determined by the most recent SPF
    calculation.

isisd/isis_spf.c

@@ -3074,7 +3074,7 @@ DEFUN(show_isis_route, show_isis_route_cmd,
 #ifndef FABRICD
       " [<level-1|level-2>]"
 #endif /* ifndef FABRICD */
-      " [<prefix-sid|backup>]"
+      " [prefix-sid] [backup]"
 #ifndef FABRICD
       " [algorithm [(128-255)]]"
 #endif /* ifndef FABRICD */