Merge pull request #1368 from pbhole/fix_dns_matching

examples: fix dns_matching
iovisor · Oct 1, 2017 · 2a6a5c5 · 2a6a5c5
2 parents c5ca2a6 + 1e21149
commit 2a6a5c5
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Showing 2 changed files with 10 additions and 12 deletions.
diff --git a/examples/networking/dns_matching/dns_matching.c b/examples/networking/dns_matching/dns_matching.c
@@ -43,7 +43,7 @@ struct dns_char_t
 } BPF_PACKET_HEADER;
 
 struct Key {
- unsigned char p[32];
+ unsigned char p[255];
 };
 
 struct Leaf {
@@ -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.
@@ -84,17 +80,19 @@ int dns_matching(struct __sk_buff *skb)
 
  u16 i = 0;
  struct dns_char_t *c;
- // This unroll worked not in latest BCC version.
- for(u8 j = 0; i<255;i++){
- if (cursor == sentinel) goto end; c = cursor_advance(cursor, 1); key.p[i++] = c->c;
+ #pragma unroll
+ for(i = 0; i<255;i++){
+ 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;
  }
  }

diff --git a/examples/networking/dns_matching/dns_matching.py b/examples/networking/dns_matching/dns_matching.py
@@ -11,8 +11,8 @@
 
 
 def encode_dns(name):
- size = 32
- if len(name) > 253:
+ size = 255
+ if len(name) > 255:
  raise Exception("DNS Name too long.")
  b = bytearray(size)
  i = 0;