fix confusion between rtlabel and rtable / rdomain

[Claudio Jeker]

rt_ifa_add() and rt_ifa_del() have a major confusion when it comes to
rtlabelid (as in labels on a route) vs rtableid (as in routing table id).
Because of this 'ifconfig <if> rtlabel XYZ' fails to add route labels to
the routing table.
The following diff fixes this issue.

To test:
ifconfig tap1001 rtlabel TEST
ifconfig tap1001 192.0.2.6/24
route -n get 192.0.2.1

-- 
:wq Claudio

Index: route.c
===================================================================
RCS file: /cvs/src/sys/net/route.c,v
retrieving revision 1.387
diff -u -p -r1.387 route.c
--- route.c     24 Jun 2019 22:26:25 -0000      1.387
+++ route.c     14 Aug 2019 17:57:07 -0000
@@ -1101,6 +1101,8 @@ rt_ifa_add(struct ifaddr *ifa, int flags
        uint8_t                  prio = ifp->if_priority + RTP_STATIC;
        int                      error;
 
+       KASSERT(rdomain == rtable_l2(rdomain));
+
        memset(&info, 0, sizeof(info));
        info.rti_ifa = ifa;
        info.rti_flags = flags;
@@ -1109,12 +1111,7 @@ rt_ifa_add(struct ifaddr *ifa, int flags
                info.rti_info[RTAX_GATEWAY] = sdltosa(ifp->if_sadl);
        else
                info.rti_info[RTAX_GATEWAY] = ifa->ifa_addr;
-
-       KASSERT(rdomain == rtable_l2(rdomain));
-       if (rdomain == rtable_l2(ifp->if_rtlabelid)) {
-               info.rti_info[RTAX_LABEL] =
-                   rtlabel_id2sa(ifp->if_rtlabelid, &sa_rl);
-       }
+       info.rti_info[RTAX_LABEL] = rtlabel_id2sa(ifp->if_rtlabelid, &sa_rl);
 
 #ifdef MPLS
        if ((flags & RTF_MPLS) == RTF_MPLS)
@@ -1158,6 +1155,8 @@ rt_ifa_del(struct ifaddr *ifa, int flags
        uint8_t                  prio = ifp->if_priority + RTP_STATIC;
        int                      error;
 
+       KASSERT(rdomain == rtable_l2(rdomain));
+
        if ((flags & RTF_HOST) == 0 && ifa->ifa_netmask) {
                m = m_get(M_DONTWAIT, MT_SONAME);
                if (m == NULL)
@@ -1173,11 +1172,7 @@ rt_ifa_del(struct ifaddr *ifa, int flags
        info.rti_info[RTAX_DST] = dst;
        if ((flags & RTF_LLINFO) == 0)
                info.rti_info[RTAX_GATEWAY] = ifa->ifa_addr;
-
-       if (rdomain == rtable_l2(ifp->if_rtlabelid)) {
-               info.rti_info[RTAX_LABEL] =
-                   rtlabel_id2sa(ifp->if_rtlabelid, &sa_rl);
-       }
+       info.rti_info[RTAX_LABEL] = rtlabel_id2sa(ifp->if_rtlabelid, &sa_rl);
 
        if ((flags & RTF_HOST) == 0)
                info.rti_info[RTAX_NETMASK] = ifa->ifa_netmask;