headers.h

本程序是一个module

struct ip{
	unsigned int      ip_version:4;			/*set "4",for IPv4*/
	unsigned int	  ip_length:4;			/*length of ip_header in 32-bit words*/
	unsigned char	  ip_tos;			/*type of service*/
	unsigned short    ip_total_length;		/*Total length of ip datagram in bytes*/
	unsigned short	  ip_id;			/*identification field*/
	unsigned short	  ip_flags;
	unsigned char	  ip_ttl;			/*time-to-live,sets upper limitfor max number
							  of routers to go through before the packet
							  is discarded*/
	
	unsigned char	  ip_protocol;			/*identifies the correct transport protocol*/
	unsigned short    ip_cksum;			/*calculated for the ip header ONLY*/
	unsigned int	  ip_source;			/*source ip*/
	unsigned int      ip_dest;			/*dest ip*/
	};


struct tcp{
	unsigned short    tcp_source_port;  		/*tcp source port*/
	unsigned short    tcp_dest_port;		/*tcp dest port*/
	unsigned int	  tcp_seqno;			/*tcp sequence number,identifies the
							  byte in the stream of data*/
        unsigned int	  tcp_ackno;			/*contains the next seq num that
        						  the sender expects to recieve*/
        unsigned int	  tcp_res1:4,			/*little-endian*/
        		  tcp_hlen:4,			/*length of tcp header in 32-bit words*/
        		  tcp_fin:1,			/*Finish flag "fin"*/
        		  tcp_syn:1,			/*Synchronize sequence numbers
        		  				  to start a connection*/
        		  tcp_rst:1,			/*Reset flag*/
        		  tcp_psh:1,			/*Push,sends data to the application*/
        		  tcp_ack:1,	    		/*acknowledge*/
        		  tcp_urg:1,			/*urgent pointer*/
        		  tcp_res2:2;
        unsigned short	  tcp_winsize;			/*maxinum number of bytes able
        						  to recieve*/
        unsigned short    tcp_cksum;			/*checksum to cover the tcp
        						  header and data portion of the
        						  packer*/
        unsigned short    tcp_urgent;			/*vaild only if the urgent flag is set ,
        						  used to transmit emergency data*/
};        

#define INTERFACE "eth0"