Hi, I am trying to cross compile a program for openwrt to capture the beacon
frames.
The program(beaconCap.c) is as follows.
*************************************************************************************************
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<pcap.h>
#include<errno.h>
#include<arpa/inet.h>
#include<net/ethernet.h>
#include<linux/wireless.h>
#include<netinet/if_ether.h>
typedef struct mac_header
{
unsigned char fc[2];
unsigned char id[2];
unsigned char add1[6];
unsigned char add2[6];
unsigned char add3[6];
unsigned char sc[2];
}mac_header;
typedef struct frame_control
{
unsigned protocol:2;
unsigned type:2;
unsigned subtype:4;
unsigned to_ds:1;
unsigned from_ds:1;
unsigned more_frag:1;
unsigned retry:1;
unsigned pwr_mgt:1;
unsigned more_data:1;
unsigned wep:1;
unsigned order:1;
}frame_control;
typedef struct beacon_header
{
unsigned char timestamp[8];
unsigned char beacon_interval[2];
unsigned char cap_info[2];
}beacon_header;
void packet_decoder(u_char * useless, const struct pcap_pkthdr *pkthdr,
const u_char * packet)
{
printf("Got Packet");
char ssid[32], *temp;
struct mac_header *p = (struct mac_header *) packet;
struct frame_control *control = (struct frame_control *)p->fc;
temp = (char *)(packet + sizeof(struct mac_header)+sizeof(struct
beacon_header));
memset (ssid, '\0', 32);
// check if frame is beacon frame
if ((control->protocol==0)&&(control->type==0)&&(control->subtype==8))
{
//temp[1] contains the size of the ssid field and temp[2] the beginning
ofthe ssid string .
memcpy (ssid, &temp[2], temp[1]);
printf ("\n\nFound SSID : \n");
printf ("Destination Add : %s\n", ether_ntoa (p->add1));
printf ("Source Add : %s\n", ether_ntoa (p->add2));
printf ("BSSID : %s\n", ether_ntoa (p->add3));
printf ("ssid = %s\n", ssid);
}
}
int main(int argc, char **argv)
{
char *dev = argv[1];
char errbuf[PCAP_ERRBUF_SIZE];
pcap_t *handle;
if(argc<2)
{
printf ("usage : %s capture_device \n", argv[0]);
exit (1);
}
printf ("Initialising capture interface..\n");
//pcap initialisation
handle = pcap_open_live (dev, BUFSIZ, 1, -1, errbuf);
if (handle == NULL)
{
printf ("pcap_open_live : %s\n", errbuf);
exit (1);
}
printf ("\nStarting Capture ...........\n");
// tell pcap to pass on captures frames to our packet_decoder fn
pcap_loop(handle, -1, packet_decoder, NULL);
return (0);
}
*************************************************************************************
I have cross compiled libpcap 1.1 with openwrt mips tool chain in my ubuntu
10.04 64bit.
libpcap in installed in /usr/local/lib
scorpio@scorpio-desktop:/usr/local/lib$ ls libpcap.
libpcap.a libpcap.so libpcap.so.1 libpcap.so.1.1.1
pcap.h in located in /usr/local/include
scorpio@scorpio-desktop:/usr/local/include$ ls pcap.h
pcap.h
only #include <pcap/pcap.h>
exists in /usr/local/include/pcap.h
However in /usr/local/include/pcap, another pcap.h is here and this is the
real pcap.h.
*******************************************************************************************************
My problem is when I cross compiled beaconCap.c with
mips-openwrt-linux-gcc beaconCap.c -o beaconCap -L /usr/local/lib/ -I
/usr/local/include/
I got following errors:
/tmp/ccA7FOzC.o: In function `main':
beaconCap.c: (.text+0x270): undefined reference to `pcap_open_live'
beaconCap.c: (.text+0x2d8): undefined reference to `pcap_loop'
collect2: ld returned 1 exit status
*******************************************************************************************************
I do not know how to solve it. Actually pcap_open_live and pcap_loop are
declared in /usr/local/include/pcap/pcap.h
Could any help me? I really need you help.
Thank you,
Jin
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