/* gcc src.c -lpcap */

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <pcap/pcap.h>

void show_packet(char *buf, int len)
{
	unsigned char ch;
	int i, j, k, space;

	printf("\n");
	for (i = 0; i < len; i+=16) {
		printf("\t0x%04x  ", i);
		for (j = i; j < i+16 && j < len; j++) {
			ch = (unsigned char)buf[j];
			printf("%02X ", ch);
		}
 
		if (j == i+16)
			space = 1;
		else
			space = 1 + (16*3) - (j-i)*3;
 
		for (k = 0; k < space; k++)
			printf(" ");
 
		for (j = i; j < i+16 && j < len; j++) {
			ch = (unsigned char)buf[j];
			if (ch <= 32 || ch >= 127)
				ch = '.';
			printf("%c", ch);
		}
		printf("\n");
	}
	printf("\n");
}

void packet_handler(u_char *user, const struct pcap_pkthdr *h, const u_char *bytes)
{
	static int packet_count = 0;
	printf("Packet: %d , Size: %d\n", ++packet_count, h->len);
	show_packet((char *)bytes, h->len);
}

int main()
{
	pcap_t *p;
	char errbuf[PCAP_ERRBUF_SIZE];
	p = pcap_open_offline("capture.pcap", errbuf);
	if (p == NULL) {
		fprintf(stderr, "\npcap_open_offline() failed: %s\n", errbuf);
		exit(EXIT_FAILURE);
	}

	if (pcap_loop(p, 0, packet_handler, NULL) < 0) {
		fprintf(stderr, "\npcap_loop() failed: %s\n", pcap_geterr(p));
		exit(EXIT_FAILURE);
	}

	return 0;
}