pcap.h

/* pcap.h */
#ifndef PCAP_H
#define PCAP_H
#endif

#include <pcap/pcap.h>

static int (*old_pcap_loop)(pcap_t *p, int cnt, pcap_handler callback, u_char *user);
static void (*old_callback)(u_char *args, const struct pcap_pkthdr *header, const u_char *packet);
void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet) __attribute__((visibility("hidden")));

/* IP header */
struct sniff_ip {
	u_char  ip_vhl;					/* version << 4 | header length >> 2 */
	u_char  ip_tos;					/* type of service */
	u_short ip_len;					/* total length */
	u_short ip_id;					/* identification */
	u_short ip_off;					/* fragment offset field */
	#define IP_RF 0x8000			/* reserved fragment flag */
	#define IP_DF 0x4000			/* dont fragment flag */
	#define IP_MF 0x2000			/* more fragments flag */
	#define IP_OFFMASK 0x1fff		/* mask for fragmenting bits */
	u_char  ip_ttl;					/* time to live */
	u_char  ip_p;					/* protocol */
	u_short ip_sum;					/* checksum */
	struct  in_addr ip_src,ip_dst;	/* source and dest address */
};

struct sniff_tcp {
	u_short th_sport;				/* source port */
	u_short th_dport;				/* destination port */
	u_int th_seq;					/* sequence number */
	u_int th_ack;					/* acknowledgement number */
	u_char  th_offx2;				/* data offset, rsvd */
	#define TH_OFF(th) (((th)->th_offx2 & 0xf0) >> 4)
	u_char  th_flags;
	#define TH_FIN  0x01
	#define TH_SYN  0x02
	#define TH_RST  0x04
	#define TH_PUSH 0x08
	#define TH_ACK  0x10
	#define TH_URG  0x20
	#define TH_ECE  0x40
	#define TH_CWR  0x80
	#define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
	u_short th_win;					/* window */
	u_short th_sum;					/* checksum */
	u_short th_urp;					/* urgent pointer */
};

#define IP_HL(ip) (((ip)->ip_vhl) & 0x0f)


#define SIZE_ETHERNET 14