winpcap sendpacket

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <WinSock2.h>
#include <Windows.h>

#define HAVE_REMOTE
#include <pcap.h>
#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "wpcap.lib")
void main(int argc, char **argv)
{
    pcap_t *fp;
    char errbuf[PCAP_ERRBUF_SIZE];
    char datagram[4096];
    unsigned long sz = make_datagram(datagram);
    if(argc != 2)
    {
        pcap_if_t * devs = nullptr;
        pcap_findalldevs(&devs, nullptr);
        printf("usage: %s interface\nAvaliable interfaces:\n", argv[0]);
        pcap_if_t * cur_dev = devs;
        while(cur_dev)
        {
            printf("%s (%s)\n", cur_dev->name, cur_dev->description);
            cur_dev = cur_dev->next;
        }
        pcap_freealldevs(devs);
        return;
    }
    if((fp = pcap_open(argv[1], 100, PCAP_OPENFLAG_PROMISCUOUS, 1000, NULL, errbuf)) == NULL)
    {
        fprintf(stderr, "\nUnable to open the adapter. %s is not supported by WinPcap\n", argv[1]);
        return;
    }
    if(pcap_sendpacket(fp, (u_char *)datagram, sz) != 0)
    {
        fprintf(stderr, "\nError sending the packet: %s\n", pcap_geterr(fp));
        return;
    }
    else
    {
        printf("Packet Send \n");
    }
    pcap_close(fp);
}