Provision to take mirror source ip from the packet

vRouter has to make provision to allow source ip of the mirror tunnel
to come from the original packet. Till now, we were using the vhost ip
address, which may not make sense in the vrf to which the mirror vm
belongs.

Change-Id: I3147d57aa16ad808327036db557387fb2ef3782c
Closes-BUG: #1545590

dp-core/vr_nexthop.c

@@ -1229,10 +1229,25 @@ nh_discard(struct vr_packet *pkt, struct vr_nexthop *nh,
     return 0;
 }
 
+static int
+nh_generate_sip(struct vr_nexthop *nh, struct vr_packet *pkt)
+{
+    struct vr_ip *iph;
+
+    iph = (struct vr_ip *)pkt_network_header(pkt);
+    if (pkt->vp_type == VP_TYPE_IP) {
+        return iph->ip_saddr;
+    }
+
+    return 0;
+}
+
 static int
 nh_udp_tunnel(struct vr_packet *pkt, struct vr_nexthop *nh,
               struct vr_forwarding_md *fmd)
 {
+    uint32_t sip = 0;
+
     struct vr_packet *tmp;
     struct vr_ip *ip;
     struct vr_udp *udp;
@@ -1251,11 +1266,32 @@ nh_udp_tunnel(struct vr_packet *pkt, struct vr_nexthop *nh,
             goto send_fail;
     }
 
-    if (nh_udp_tunnel_helper(pkt, nh->nh_udp_tun_sport,
-                             nh->nh_udp_tun_dport, nh->nh_udp_tun_sip,
-                             nh->nh_udp_tun_dip) == false) {
+    if (nh->nh_family == AF_INET) {
+        if (nh->nh_flags & NH_FLAG_TUNNEL_SIP_COPY) {
+            sip = nh_generate_sip(nh, pkt);
+        }
+
+        if (!sip) {
+            sip = nh->nh_udp_tun_sip;
+        }
+
+        if (nh_udp_tunnel_helper(pkt, nh->nh_udp_tun_sport,
+                    nh->nh_udp_tun_dport, sip,
+                    nh->nh_udp_tun_dip) == false) {
+            goto send_fail;
+        }
+
+        if (pkt_len(pkt) > ((1 << sizeof(ip->ip_len) * 8)))
+            goto send_fail;
+
+        ip = (struct vr_ip *)(pkt_data(pkt));
+        udp = (struct vr_udp *)((char *)ip + ip->ip_hl * 4);
+        udp->udp_csum = vr_ip_partial_csum(ip);
+
+    } else {
         goto send_fail;
     }
+
     pkt_set_network_header(pkt, pkt->vp_data);
 
     if (pkt_len(pkt) > ((1 << sizeof(ip->ip_len) * 8)))

include/vr_nexthop.h

@@ -55,6 +55,7 @@ enum nexthop_type {
 #define NH_FLAG_VNID                        0x08000
 #define NH_FLAG_ROUTE_LOOKUP                0x10000
 #define NH_FLAG_UNKNOWN_UC_FLOOD            0x20000
+#define NH_FLAG_TUNNEL_SIP_COPY             0x40000
 
 #define NH_SOURCE_INVALID                   0
 #define NH_SOURCE_VALID                     1

utils/nh.c

@@ -166,6 +166,10 @@ nh_flags(uint32_t flags, uint8_t type, char *ptr)
         case NH_FLAG_UNKNOWN_UC_FLOOD:
             strcat(ptr, "Unicast Flood, ");
             break;
+
+        case NH_FLAG_TUNNEL_SIP_COPY:
+            strcat(ptr, "Copy SIP, ");
+            break;
         }
     }
     return ptr;