mrelay

/************************************************************************
 *                                  *
 *  mrelay - Copyright 2011 Matteo Croce <rootkit85@yahoo.it>   *
 *                                  *
 ***********************************************************************/

//#include <stdio.h>
#include <stdlib.h>
//#include <string.h>

#include <pcap.h>

#define DEV1    "wlan0"
#define DEV2    "eth0"

void got_packet(u_char *, const struct pcap_pkthdr *, const u_char *);

int main(int argc, char *argv[])
{
    pcap_t *handle;
    char errbuf[PCAP_ERRBUF_SIZE] = {0};
    struct bpf_program fp;

    handle = pcap_open_live(DEV1, BUFSIZ, 0, 0, errbuf);
    if(!handle) {
        printf("!handle");
        return 1;
    }

    pcap_compile(handle, &fp, "host 239.255.255.250 && udp port 1900", 1, 0);
//  pcap_compile(handle, &fp, "(host 239.255.255.250 && udp port 1900) || (host 224.0.0.251 && udp port 5353)", 1, 0);
    pcap_setfilter(handle, &fp);

    pcap_loop(handle, -1, got_packet, NULL);

    pcap_close(handle);

    return 0;
}

void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet)
{
    printf("Got packet\n");

    char errbuf[PCAP_ERRBUF_SIZE];
    pcap_t* inject_int_desc = pcap_open_live(DEV2, BUFSIZ, 0, 0, errbuf);

    if(!inject_int_desc) {
        printf("Error: %s\n", errbuf);
        exit(1);
    }

    pcap_inject(inject_int_desc, packet, header->len);

    pcap_close(inject_int_desc);
}