pktheader.h

#ifndef _PKT_HEADER_H_
#define _PKT_HEADER_H_

#include <netinet/in.h>

/* Ethernet header */
#define ETHERNET_HDR_SIZE 14
#define ETHER_ADDR_LEN	   6

struct sniff_ethernet 
{
   u_char  ether_dhost[ETHER_ADDR_LEN];    /* destination host address */
   u_char  ether_shost[ETHER_ADDR_LEN];    /* source host address */
   u_short ether_type;                     /* IP? ARP? RARP? etc */
};

/* 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 */
};

#define IP_HL(ip)               (((ip)->ip_vhl) & 0x0f)
#define IP_V(ip)                (((ip)->ip_vhl) >> 4)


/* TCP header */
typedef u_int tcp_seq;

struct sniff_tcp 
{
   u_short th_sport;               /* source port */
   u_short th_dport;               /* destination port */
   tcp_seq th_seq;                 /* sequence number */
   tcp_seq 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 */
};

/* Command line */
#define UNIFORM_DROP      221
#define EXPONENTIAL_DROP  222
#define CAPTURE           223

#endif // _PKT_HEADER_H_