Programming snag

[appy20]

Hi all!
I am a novice in using libpcap library and I have been assigned work to capture SIP traffic using libpcap. However the system I am working on is connected to a bridge and inspite of using filters the code seems to capture all other sorts of traffic. I am posting the code here hoping for some help.
#include<pcap.h>
#include<stdlib.h>
#include<string.h>
#define MAXBYTES2CAPTURE 2074

void processPacket(u_char* arg,const struct pcap_pkthdr *pkthdr,const u_char *packet)
{
int i=0,*counter=(int*)arg;
printf("\nPacket count = %d",++(*counter));
printf("\nrecieved packet size = %d",pkthdr->len);
printf("\npayload\n");
for(i=0;i<pkthdr->len;i++)
{ if(isprint(packet[i]))
printf("%c",packet[i]);
else
printf(". ");
if(((i%16==0)&&(i!=0))||i==pkthdr->len-1)
printf("\n");
}
return;
}
int main()
{
int i=0,count=0;
pcap_t *desc=NULL;
char device[] = "my_bridge";
char filter_exp[] = "port 5060"; /* The filter expression */
bpf_u_int32 mask; /* The netmask of our sniffing device */
bpf_u_int32 net; /* The IP of our sniffing device */
char errbuf[PCAP_ERRBUF_SIZE];
struct bpf_program fp;
memset(errbuf,0,PCAP_ERRBUF_SIZE);
if (pcap_lookupnet(device, &net, &mask, errbuf) == -1) {
fprintf(stderr, "Can't get netmask for device %s\n", device);
net = 0;
mask = 0;
}
printf("\nAfter looknet");
printf("\nopening device %s",device);
printf("\nnetmaskv %ud",mask);
printf("\nnet %ud",net);
desc=pcap_open_live(device,MAXBYTES2CAPTURE,1,512, errbuf);
if (pcap_compile(desc, &fp, filter_exp, 1, net) == -1) {
fprintf(stderr, "Couldn't parse filter %s: %s\n", filter_exp, pcap_geterr(desc));
return(2);
}
else
printf("\ncompile OK");
if (pcap_setfilter(desc, &fp) == -1) {
fprintf(stderr, "Couldn't install filter %s: %s\n", filter_exp, pcap_geterr(desc));
return(2);
}
else printf("\nfilter ok");
pcap_loop(desc,-1,processPacket,(u_char*)&count);
return 0;
}

[Rubberman]

When you post code in these forums, PLEASE surround the code in code blocks, as in:

// This is some code.
    // As you can see, indents are now preserved... :-)