Filter out sockets for loopback and unknown interfaces (#260)

* RTT: filter out sockets for loopback and unknown interfaces

Signed-off-by: Mohamed Mahmoud <mmahmoud@redhat.com>

* filter loopback and unknown interfaces with pkt drop feature

Signed-off-by: Mohamed Mahmoud <mmahmoud@redhat.com>

---------

Signed-off-by: Mohamed Mahmoud <mmahmoud@redhat.com>

bpf/pkt_drops.h

@@ -17,7 +17,10 @@ static inline int trace_pkt_drop(void *ctx, u8 state,
     u16 family = 0,flags = 0;
 
     id.if_index = skb->skb_iif;
-
+    // filter out TCP sockets with unknown or loopback interface
+    if (id.if_index == 0 || id.if_index == 1) {
+        return 0;
+    }
     // read L2 info
     set_key_with_l2_info(skb, &id, &family);
 

bpf/rtt_tracker.h

@@ -102,6 +102,10 @@ static inline int calculate_flow_rtt_tcp(struct sock *sk, struct sk_buff *skb) {
     __builtin_memset(&id, 0, sizeof(id));
 
     id.if_index = BPF_CORE_READ(skb, skb_iif);
+    // filter out TCP sockets with unknown or loopback interface
+    if (id.if_index == 0 || id.if_index == 1) {
+        return 0;
+    }
     len = BPF_CORE_READ(skb, len);
 
     // read L2 info