examples:dns_matching: fixed loop break condition

The for loop was copying garbase characters after domain name. Fixed this by adding correct terminating condition. Also removed unnecessary code Signed-off-by: Prashant Bhole <[email protected]>
iovisor · Sep 28, 2017 · 1e21149 · 1e21149
1 parent 3c40c02
commit 1e21149
Showing 1 changed file with 5 additions and 7 deletions.
diff --git a/examples/networking/dns_matching/dns_matching.c b/examples/networking/dns_matching/dns_matching.c
@@ -70,10 +70,6 @@ int dns_matching(struct __sk_buff *skb)
  struct udp_t *udp = cursor_advance(cursor, sizeof(*udp));
  if(udp->dport == 53){
 
- // Our Cursor + the length of our udp packet - size of the udp header
- // - the two 16bit values for QTYPE and QCLASS.
- u8 *sentinel = cursor + udp->length - sizeof(*udp) - 4;
-
  struct dns_hdr_t *dns_hdr = cursor_advance(cursor, sizeof(*dns_hdr));
 
  // Do nothing if packet is not a request.
@@ -86,15 +82,17 @@ int dns_matching(struct __sk_buff *skb)
  struct dns_char_t *c;
  #pragma unroll
  for(i = 0; i<255;i++){
- if (cursor == sentinel) goto end; c = cursor_advance(cursor, 1); key.p[i] = c->c;
+ c = cursor_advance(cursor, 1);
+ if (c->c == 0)
+ break;
+ key.p[i] = c->c;
  }
- end:
- {}
 
  struct Leaf * lookup_leaf = cache.lookup(&key);
 
  // If DNS name is contained in our map, drop packet.
  if(lookup_leaf) {
+ bpf_trace_printk("Matched1\n");
  return 0;
  }
  }