网络协议结构体定义(eth,ip,tcp,udp,icmp...)

// i386 is little_endian.
#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN   (1)   //BYTE ORDER
#else
#error Redefine LITTLE_ORDER
#endif

//Mac头部，总长度14字节
typedef struct _eth_hdr
{
unsigned char dstmac[6]; //目标mac地址
unsigned char srcmac[6]; //源mac地址
unsigned short eth_type; //以太网类型
}eth_hdr;

//IP头部，总长度20字节
typedef struct _ip_hdr
{
#if LITTLE_ENDIAN
unsigned char ihl:4;     //首部长度
unsigned char version:4, //版本
#else
unsigned char version:4, //版本
unsigned char ihl:4;     //首部长度
#endif
unsigned char tos;       //服务类型
unsigned short tot_len;  //总长度
unsigned short id;       //标志
unsigned short frag_off; //分片偏移
unsigned char ttl;       //生存时间
unsigned char protocol;  //协议
unsigned short chk_sum;  //检验和
struct in_addr srcaddr;  //源IP地址
struct in_addr dstaddr;  //目的IP地址
}ip_hdr;

//TCP头部，总长度20字节
typedef struct _tcp_hdr
{
unsigned short src_port;    //源端口号
unsigned short dst_port;    //目的端口号
unsigned int seq_no;        //序列号
unsigned int ack_no;        //确认号
#if LITTLE_ENDIAN
unsigned char reserved_1:4; //保留6位中的4位首部长度
unsigned char thl:4;        //tcp头部长度
unsigned char flag:6;       //6位标志
unsigned char reseverd_2:2; //保留6位中的2位
#else
unsigned char thl:4;        //tcp头部长度
unsigned char reserved_1:4; //保留6位中的4位首部长度
unsigned char reseverd_2:2; //保留6位中的2位
unsigned char flag:6;       //6位标志
#endif
unsigned short wnd_size;    //16位窗口大小
unsigned short chk_sum;     //16位TCP检验和
unsigned short urgt_p;      //16为紧急指针
}tcp_hdr;

//UDP头部，总长度8字节
typedef struct _udp_hdr
{
unsigned short src_port; //远端口号
unsigned short dst_port; //目的端口号
unsigned short uhl;      //udp头部长度
unsigned short chk_sum;  //16位udp检验和
}udp_hdr;

//ICMP头部，总长度4字节
typedef struct _icmp_hdr
{
unsigned char icmp_type;   //类型
unsigned char code;        //代码
unsigned short chk_sum;    //16位检验和
}icmp_hdr;

/*********************************************/
//计算机网络各种协议的结构
#define ETHER_ADDR_LEN 6 //NIC物理地址占6字节
#define MAXDATA 10240
/*
网络实验程序
数据包中的TCP包头,IP包头,UDP包头,ARP包,Ethernet包等.
以及各种表.路由寻址表,地址解析协议表DNS表等
*/
#define ETHERTYPE_IP 0x0800   //IP Protocal
#define ETHERTYPE_ARP 0x0806   //Address Resolution Protocal
#define ETHERTYPE_REVARP 0x0835   //Reverse Address Resolution Protocal 逆地址解析协议
/*********************************************/
//ethernet
typedef struct ether_header
{
u_char ether_dhost[ETHER_ADDR_LEN];
u_char ether_shost[ETHER_ADDR_LEN];
u_short ether_type;
}ETH_HEADER;
/*********************************************/
//ether_header eth;
/*********************************************/
//arp
typedef struct arphdr
{
u_short ar_hrd;
u_short ar_pro;
u_char ar_hln;
u_char ar_pln;
u_short ar_op;
}ARP_HEADER;
/*********************************************/
/*********************************************/
//IP报头
typedef struct ip
{
u_int ip_v:4; //version(版本)
u_int ip_hl:4; //header length(报头长度)
u_char ip_tos;
u_short ip_len;
u_short ip_id;
u_short ip_off;
u_char ip_ttl;
u_char ip_p;
u_short ip_sum;
struct in_addr ip_src;
struct in_addr ip_dst;
}IP_HEADER;
/*********************************************/
/*********************************************/
//TCP报头结构体
typedef struct tcphdr
{
u_short th_sport;
u_short th_dport;
u_int th_seq;
u_int th_ack;
u_int th_off:4;
u_int th_x2:4;
u_char th_flags;
u_short th_win;
u_short th_sum;
u_short th_urp;
}TCP_HEADER;
#define TH_FIN 0x01
#define TH_SYN 0x02
#define TH_RST 0x04
#define TH_PUSH 0x08
#define TH_ACK 0x10
#define TH_URG 0x20

/*********************************************/
/*********************************************/
//UDP报头结构体*/
typedef struct udphdr
{
u_short uh_sport;
u_short uh_dport;
u_short uh_ulen;
u_short uh_sum;
}UDP_HEADER;

/*********************************************/
//=============================================
/*********************************************/
/*ARP与ETHERNET生成的报头*/
typedef struct ether_arp
{
struct arphdr ea_hdr;
u_char arp_sha[ETHER_ADDR_LEN];
u_char arp_spa[4];
u_char arp_tha[ETHER_ADDR_LEN];
u_char arp_tpa[4];
}ETH_ARP;
#define arp_hrd ea_hdr.ar_hrd
#define arp_pro ea_hdr.ar_pro
#define arp_hln ea_hdr.ar_hln
#define arp_pln ea_hdr.ar_pln
#define arp_op ea_hdr.ar_op
#define ARPHRD 1

/*********************************************/
/*********************************************/
//tcp与ip生成的报头
typedef struct packet_tcp
{
struct ip ip;
struct tcphdr tcp;
u_char data[MAXDATA];
}TCP_IP;

/*********************************************/
/*********************************************/
//udp与ip生成的报头
typedef struct packet_udp
{
struct ip ip;
struct udphdr udp;
}UDP_IP;
/*********************************************/
/*********************************************/

//ICMP的各种形式
//icmpx,x==icmp_type;
//icmp报文(能到达目的地,响应-请求包)
struct icmp8
{
u_char icmp_type; //type of message(报文类型)
u_char icmp_code; //type sub code(报文类型子码)
u_short icmp_cksum;
u_short icmp_id;
u_short icmp_seq;
char icmp_data[1];
};

//icmp报文(能返回目的地,响应-应答包)
struct icmp0
{
u_char icmp_type; //type of message(报文类型)
u_char icmp_code; //type sub code(报文类型子码)
u_short icmp_cksum;
u_short icmp_id;
u_short icmp_seq;
char icmp_data[1];
};

//icmp报文(不能到达目的地)
struct icmp3
{
u_char icmp_type; //type of message(报文类型)
u_char icmp_code; //type sub code(报文类型子码),例如:0网络原因不能到达,1主机原因不能到达...
u_short icmp_cksum;
u_short icmp_pmvoid;
u_short icmp_nextmtu;
char icmp_data[1];
};
//icmp报文(重发结构体)
struct icmp5
{
u_char icmp_type; //type of message(报文类型)
u_char icmp_code; //type sub code(报文类型子码)
u_short icmp_cksum;
struct in_addr icmp_gwaddr;
char icmp_data[1];
};
struct icmp11
{
u_char icmp_type; //type of message(报文类型)
u_char icmp_code; //type sub code(报文类型子码)
u_short icmp_cksum;
u_int icmp_void;
char icmp_data[1];
};