WinPcap 2

Capture the Packet

#include<pcap.h>
#pragma comment(lib,"ws2_32.lib")
#pragma comment(lib,"wpcap.lib")
#pragma warning(disable:4996)
void packet_view(u_char *, const struct pcap_pkthdr *, const u_char *);
void print_hex(const u_char *, int);
int main(void)
{
    char *dev;                    // device name;
    pcap_t *pd;                    // packet descripter
    bpf_u_int32 net, subnet;    // network, subnetmask
    char errbuf[PCAP_ERRBUF_SIZE];    // error buffer
    
    if (!(dev = pcap_lookupdev(errbuf))){    // find device
        printf("[!] pcap_lookupdev\n");
        return -1;
    }
    if (pcap_lookupnet(dev, &net, &subnet, errbuf) < 0){    // get network, subnetmask
        printf("[!] pcap_lookupnet\n");
        return -1;
    }
    /* pcap_open_live
        device
        maximum capture length
        promiscuous mode
        timeout(ms)
        error buffer
    */
    if (!(pd = pcap_open_live(dev, 65535, 1, 3000, errbuf))) {
        printf("[!] pcap_open_live\n");
        return -1;
    }
    printf("[-] Listening");
    /* pcap_loop
        packet descriptor
        receive packet num(0:Endlessloop)
        received packet processing fuction
        user parameter
    */
    if (pcap_loop(pd, 10, packet_view, NULL) < 0) {
        printf("[!] pcap_loop\n");
        return -1;
    }
    return 0;
}
// received packet processer
/* packet_view
    user parameter
    header
    packet data
*/
void packet_view(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data)
{
    int len = 0;
    printf("[*] Received Packet\n");
    
    print_hex(pkt_data, header->len);
    
}
void print_hex(const u_char *data, int len)
{
    int i, j;
    printf("Addr   ");
    for (i = 0; i < 16; i++)
        printf("%02X ", i);
    for (i = 0; i < 16; i++)
        printf("%X", i);
    printf("\n");
 
    for (i = 0; i * 16 < len; i++) {
        printf("0x%04X ", i * 16);
        for (j = 0; j < 16; j++)
            printf("%02X ", (data + 16 * i)[j]);
        for (j = 0; j < 16; j++) {
            if (((data + 16 * i)[j]>0x1f) && ((data + 16 * i)[j] < 0x7F))
                printf("%c", (data + 16 * i)[j]);
            else
                printf(".");
        }
        printf("\n");
    }
    printf("\n");
}