parse.c

#include "parse.h"

int parseIP(u_char *pkt_data)
{
    ip_header *ih;
    u_int ip_len;
    ih = (ip_header *)pkt_data;

    ip_len = (ih->ver_ihl & 0xf) << 2;

    printf("[IP]%d.%d.%d.%d -> %d.%d.%d.%d\n",
           ih->saddr.byte1,
           ih->saddr.byte2,
           ih->saddr.byte3,
           ih->saddr.byte4,
           ih->daddr.byte1,
           ih->daddr.byte2,
           ih->daddr.byte3,
           ih->daddr.byte4);

    playByte(*(pkt_data + 0)); // 1st : version and len
    playByte(*(pkt_data + 1));    // 2nd : service
    playByte(*(pkt_data + 6));    // 7th : flag and offset
    playByte(*(pkt_data + 7));
    playByte(*(pkt_data + 8)); // ttl
    playByte(*(pkt_data + 9)); // protocol
    return ip_len;
}

void parseARP(u_char *data)
{

    playByte(*(data + 0)); // hardware type
    playByte(*(data + 1));
    playByte(*(data + 2)); // proto type
    playByte(*(data + 3));

    playByte(*(data + 6)); // op code
    playByte(*(data + 7));

    printf("ARP OPERATION : 0x%x\n", ntohs(((arp_header *)data)->ar_op));
}

void parseUDP(u_char *data)
{
    udp_header *hdr;
    hdr = (udp_header *)data;

    // length
    playByte(*(data + 4));
    playByte(*(data + 5));

    printf("[UDP]Port %d ---> %d\n", ntohs(hdr->sport), ntohs(hdr->dport));
}

int parseTCP(u_char *data)
{
    tcp_header *hdr;
    int hdrlen;
    hdr = (tcp_header *)data;

    playByte(*(data + 12)); // offset
    playByte(*(data + 13)); // flag
    playByte(*(data + 14)); // window size
    playByte(*(data + 15));
    playByte(*(data + 17)); // urgent pointer

    printf("[TCP]Port %d ---> %d\n", ntohs(hdr->source), ntohs(hdr->dest));
    hdrlen = (hdr->doff) << 2;
    return hdrlen;
}

void parseICMP(u_char *data)
{
    icmp_header *hdr;
    hdr = (icmp_header *)data;

    playByte(*(data + 0)); // type and code

    printf("[ICMP]TYPE -- 0x%x || CODE -- 0x%x\n", ntohs(hdr->type), ntohs(hdr->code));
}