libnfcontrack weirdness

[Alex Bligh <alex@xxxxxxxxxxx>]

I may be doing something stupid here, but I can't seem to get information
on an existing connection through libnfconntrack.

Code extract below. When passed a 4-tuple describing an existing connection,
it prints "Found connection", when passed other stuff, it does not. So
that much is working.

However, no ATTR_ stuff relating to the connection is printed out
except for ATTR_ORIG_PORT_* which are synonyms of what has been
set with nfct_set_attr.

I am having difficulty finding documentation for this, but surely
there must be a way to get the information out from the connection
itself.

--
Alex Bligh



/* Get the prenat source port associated with a connection */
u_int16_t getprenatport(struct in_addr * local_addr, struct in_addr * 
remote_addr, int local_port, int remote_port)
{
   struct nfct_handle *h;
   struct nf_conntrack *ct;
   u_int16_t port =0;

   if (NULL == (ct = nfct_new()))
	return 0;

   nfct_set_attr_u8(ct, ATTR_L3PROTO, AF_INET);
   nfct_set_attr_u32(ct, ATTR_IPV4_SRC, *((u_int32_t *)remote_addr));
   nfct_set_attr_u32(ct, ATTR_IPV4_DST, *((u_int32_t *)local_addr));

   nfct_set_attr_u8(ct, ATTR_L4PROTO, IPPROTO_TCP);
   nfct_set_attr_u16(ct, ATTR_PORT_SRC, htons(remote_port));
   nfct_set_attr_u16(ct, ATTR_PORT_DST, htons(local_port));


   h = nfct_open(CONNTRACK, 0);
   if (!h) {
     return 0;
   }

   if (nfct_query(h, NFCT_Q_GET, ct)<0)
     {
       nfct_close(h);
       return 0;
     }

   dolog ("Found connection "
          "ATTR_ORIG_COUNTER_PACKETS=%d "
          "ATTR_REPL_COUNTER_PACKETS=%d "
          "ATTR_REPL_PORT_SRC=%d "
          "ATTR_REPL_PORT_DST=%d "
          "ATTR_ORIG_PORT_SRC=%d "
          "ATTR_ORIG_PORT_DST=%d "
          "ATTR_MASTER_PORT_SRC=%d "
          "ATTR_MASTER_PORT_DST=%d",
          ntohs(nfct_get_attr_u32(ct, ATTR_ORIG_COUNTER_PACKETS)),
          ntohs(nfct_get_attr_u32(ct, ATTR_REPL_COUNTER_PACKETS)),
          ntohs(nfct_get_attr_u16(ct, ATTR_REPL_PORT_SRC)),
          ntohs(nfct_get_attr_u16(ct, ATTR_REPL_PORT_DST)),
          ntohs(nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC)),
          ntohs(nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST)),
          ntohs(nfct_get_attr_u16(ct, ATTR_MASTER_PORT_SRC)),
          ntohs(nfct_get_attr_u16(ct, ATTR_MASTER_PORT_DST))
          );

   port =  ntohs(nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST));
   nfct_close(h);
   return 0;

}

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