Using the correct FMD and setting pkt_type correctly for mirrored pac…

…kets

If port mirroring is enabled, cloned packet is subjected to mirroring
using the original packet's forwarding metadata. If mirroring code
changes the metadata content, original packet will be forwarded as per
the changed fmd and results in wrong forwarding.

In the current case, mirroring is to a VM in different VN (hence new VRF)
and mirroring code is modifying the fmd's dvrf to new VRF.
The original ARP packet's L2 and L3 looksups are happening on the
modified VRF resulting in ARP getting dropped.

Also the type of packet is identified using vr_pkt_type() after packet
is mirrored. This is resulting in wrong pkt_type being used for mirrored
packet hence the source IP packet the mirrored packet is not correctly
computed.

As a fix, new FMD is used for mirrored packet and packet type is
identified before mirroring itself.

Change-Id: I00cc36161aac47be799c00083d8b82ecc030ba15
closes-bug: #1549727

dp-core/vr_datapath.c

@@ -553,16 +553,17 @@ vr_virtual_input(unsigned short vrf, struct vr_interface *vif,
     fmd.fmd_vlan = vlan_id;
     fmd.fmd_dvrf = vrf;
 
+    if (vr_pkt_type(pkt, 0, &fmd) < 0) {
+        vif_drop_pkt(vif, pkt, 1);
+        return 0;
+    }
+
     if (vif->vif_flags & VIF_FLAG_MIRROR_RX) {
         mfmd = fmd;
         mfmd.fmd_dvrf = vif->vif_vrf;
-        vr_mirror(vif->vif_router, vif->vif_mirror_id, pkt, &fmd);
+        vr_mirror(vif->vif_router, vif->vif_mirror_id, pkt, &mfmd);
     }
 
-    if (vr_pkt_type(pkt, 0, &fmd) < 0) {
-        vif_drop_pkt(vif, pkt, 1);
-        return 0;
-    }
 
     /*
      * we really do not allow any broadcast packets from interfaces

dp-core/vr_mirror.c

@@ -374,11 +374,11 @@ vr_mirror(struct vrouter *router, uint8_t mirror_id,
     unsigned char default_mme[2] = {0xff, 0x0};
     void *mirror_md;
     unsigned char *buf;
-    struct vr_nexthop *nh;
+    struct vr_nexthop *nh, *pkt_nh;
     struct vr_pcap *pcap;
     struct vr_mirror_entry *mirror;
     struct vr_mirror_meta_entry *mme;
-    struct vr_nexthop *pkt_nh;
+    struct vr_forwarding_md new_fmd;
 
     /* If the packet is already mirrored, dont mirror again */
     if (pkt->vp_flags & VP_FLAG_FROM_DP)
@@ -388,6 +388,11 @@ vr_mirror(struct vrouter *router, uint8_t mirror_id,
     if (!mirror)
         return 0;
 
+    if (fmd) {
+        memcpy(&new_fmd, fmd, sizeof(*fmd));
+        fmd = &new_fmd;
+    }
+
     if (fmd->fmd_flow_index >= 0) {
         mme = (struct vr_mirror_meta_entry *)vr_itable_get(router->vr_mirror_md,
                                                            fmd->fmd_flow_index);