pcap_test.c

/* pcap_test.c */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <arpa/inet.h>
#include "net_header.h"

#define COUNT1(x) x/16
#define COUNT2(x) x%16
/*
   Print Packet's hex value
*/
void print_packet(const u_char *packet, const DWORD total_size) {
    unsigned int i=0;
    unsigned int j=0;

    for(i=0; i<COUNT1(total_size); i++) {
	printf("[%03x] ", i*16);
	for(j=0; j<16; j++)
	    printf("%02x ", (*((char*)packet+((i*16)+j))&0xff));
	printf("\n");
    }
    if(COUNT2(total_size) > 0) {
	printf("[%03x] ", i*16);
	for(j=0; j<COUNT2(total_size); j++)
	    printf("%02x ", (*((char*)packet+((i*16)+j))&0xff));
	printf("\n\n");
    }
}

#define Offset(x, y) (x*16 + y) 
/*
   Print Packet's data except ETHERNET HEADER, IP HEADER, TCP HEADER
*/
void print_data(const char *data, const DWORD data_len) {
    unsigned int i=0;
    unsigned int j=0;

    fflush(stdout);
    puts("==========================================");
    printf("|               Data[0x%x]               |\n", data_len); 
    puts("==========================================");
    for(i=0; i<COUNT1(data_len); i++) {
	printf("[%04x] ", i*16);
	for(j=0; j<16; j++)
	    printf("%c", isprint(*(data+Offset(i,j)))?(char)*(data+Offset(i,j)):'.');
	printf("\n");
    }
    if(COUNT2(data_len) > 0) {
	printf("[%04x] ", i*16);
	for(j=0; j<COUNT2(data_len); j++)
	    printf("%c", isprint(*(data+Offset(i,j)))?(char)*(data+Offset(i,j)):'.');
	printf("\n");
    }
}

#define l_endian16(x) ntohs(x & 0xffff)
#define l_endian32(x) ntohl(x & 0xffffffff)
/*
   store ETHERNET, IP, TCP HEADER from packet
*/
DWORD get_headers(pether_h peh, pip_h pih, ptcp_h pth, const u_char *packet) {
    char* temp[1024] = {0, };
    DWORD data_len = 0;

    /* Get a Ethernet Header */
    memcpy(peh, packet, ETHERNET_SIZE);

    /* Get a IP Header */
    if(peh->Type == TYPE_IP) {
	memcpy(temp, packet+ETHERNET_SIZE, IP_MIN_SIZE);
	memcpy(pih, temp, ip_h_len(temp));
	pih->Total_len = l_endian16(((pip_h)temp)->Total_len);
	pih->Identification = l_endian16(((pip_h)temp)->Identification);
	pih->Flag_Frag = l_endian16(((pip_h)temp)->Flag_Frag);
	memset(temp, 0, sizeof(temp));

	/* Get a TCP Header */
	if(pih->Protocol == TCP_PROTOCOL) {
	    memcpy(temp, packet+ETHERNET_SIZE+ip_h_len(pih), TCP_MIN_SIZE);
	    memcpy(pth, temp, tcp_h_len(temp));
	    
	    pth->Source = l_endian16(((ptcp_h)temp)->Source);
	    pth->Dest = l_endian16(((ptcp_h)temp)->Dest);
	    pth->Seq_num = l_endian32(((ptcp_h)temp)->Seq_num);
	    pth->Ack_num = l_endian32(((ptcp_h)temp)->Ack_num);
	    pth->Len_Rsv_Code = l_endian16(((ptcp_h)temp)->Len_Rsv_Code);

	    /* ip header's total length
	       - ip header's header length
	       - tcp header's header length
	     */
	    data_len = data_len(pih, pth);
	    /* No data */
	    if(data_len == 0)     return 0;
	    else {
		return ETHERNET_SIZE+ip_h_len(pih)+tcp_h_len(temp);
	    }
	}
	else return ETHERNET_SIZE+ip_h_len(pih);
    }
    else return ETHERNET_SIZE;
}

/*
   Print a ETHERNET HEADER
*/
void print_ether(const pether_h peh) {
    fflush(stdout);
    puts("==========================================");
    puts("|           Ethernet Header              |"); 
    puts("==========================================");
    printf("MAC Destination Address : ");
    for(unsigned int i=0; i<6; i++) {
	printf("%02x", peh->Dest[i]&0xff);
	if(i==5) break;
	printf(":");
    }
    printf("\n");
    
    printf("MAC Source Address      : ");
    for(unsigned int i=0; i<6; i++) {
	printf("%02x", peh->Source[i]&0xff);
	if(i==5) break;
	printf(":");
    }
    printf("\n");
}

/*
   Print a IP HEADER
*/
void print_ip(const pip_h pih) {
    char temp[INET_ADDRSTRLEN] = {0, };

    fflush(stdout);
    puts("==========================================");
    puts("|		  IP Header                |"); 
    puts("==========================================");
    printf("IP Source Address      : ");
    inet_ntop(AF_INET, &(pih->Source), temp, INET_ADDRSTRLEN);
    puts(temp);
    printf("IP Destination Address : ");
    inet_ntop(AF_INET, &(pih->Dest), temp, INET_ADDRSTRLEN);
    puts(temp);
}

/*
   Print a TCP HEADER
*/
void print_tcp(const ptcp_h pth) {
    fflush(stdout);
    puts("==========================================");
    puts("|		 TCP Header                |"); 
    puts("==========================================");
    printf("Source port     : %u\n", pth->Source);
    printf("Destnation port : %u\n", pth->Dest);
}