#include <stdio.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <time.h>
#include <windows.h>
#include <string.h>
#include <stdlib.h>
#pragma comment(lib,"ws2_32.lib")

#define IPVER   4           //IP协议预定
#define MAX_BUFF_LEN 65500  //发送缓冲区最大值

typedef struct ip_hdr    //定义IP首部
{
UCHAR h_verlen;            //4位首部长度,4位IP版本号
UCHAR tos;                //8位服务类型TOS
USHORT total_len;        //16位总长度（字节）
USHORT ident;            //16位标识
USHORT frag_and_flags;    //3位标志位
UCHAR ttl;                //8位生存时间 TTL
UCHAR proto;            //8位协议 (TCP, UDP 或其他)
USHORT checksum;        //16位IP首部校验和
ULONG sourceIP;            //32位源IP地址
ULONG destIP;            //32位目的IP地址
}IP_HEADER;

typedef struct tsd_hdr //定义TCP伪首部
{
ULONG saddr;    //源地址
ULONG daddr;    //目的地址
UCHAR mbz;        //没用
UCHAR ptcl;        //协议类型
USHORT tcpl;    //TCP长度
}PSD_HEADER;

typedef struct tcp_hdr //定义TCP首部
{
USHORT th_sport;            //16位源端口
USHORT th_dport;            //16位目的端口
ULONG th_seq;                //32位序列号
ULONG th_ack;                //32位确认号
UCHAR th_lenres;            //4位首部长度/6位保留字
UCHAR th_flag;                //6位标志位
USHORT th_win;                //16位窗口大小
USHORT th_sum;                //16位校验和
USHORT th_urp;                //16位紧急数据偏移量
}TCP_HEADER;

//CheckSum:计算校验和的子函数
USHORT checksum(USHORT *buffer, int size)
{
    unsigned long cksum=0;
    while(size >1)
    {
        cksum+=*buffer++;
        size -=sizeof(USHORT);
    }
    if(size)
    {
        cksum += *(UCHAR*)buffer;
    }

    cksum = (cksum >> 16) + (cksum & 0xffff);
    cksum += (cksum >>16);
    return (USHORT)(~cksum);
}

int main(int argc, char* argv[])
{
    WSADATA WSAData;
    SOCKET sock;
   
    IP_HEADER ipHeader;
    TCP_HEADER tcpHeader;
    PSD_HEADER psdHeader;

    char Sendto_Buff[MAX_BUFF_LEN];  //发送缓冲区
    unsigned short check_Buff[MAX_BUFF_LEN]; //检验和缓冲区
    const char tcp_send_data[]={"This is my homework of networt,I am happy!"};

    BOOL flag;
    int rect,nTimeOver;

    if (argc!= 5)
    {
        printf("Useage: SendTcp soruce_ip source_port dest_ip dest_port \n");
        return false;
    }

    if (WSAStartup(MAKEWORD(2,2), &WSAData)!=0)
    {
        printf("WSAStartup Error!\n");
        return false;
    }

    if ((sock=WSASocket(AF_INET,SOCK_RAW,IPPROTO_IP,NULL,0,WSA_FLAG_OVERLAPPED))==INVALID_SOCKET)
    {
        printf("Socket Setup Error!\n");
        return false;
    }
    flag=true;
    if (setsockopt(sock,IPPROTO_IP, IP_HDRINCL,(char *)&flag,sizeof(flag))==SOCKET_ERROR)
    {
        printf("setsockopt IP_HDRINCL error!\n");
        return false;
    }
    nTimeOver=1000;
    if (setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, (char*)&nTimeOver, sizeof(nTimeOver))==SOCKET_ERROR)
    {
        printf("setsockopt SO_SNDTIMEO error!\n");
        return false;
    }

    //填充IP首部
    ipHeader.h_verlen=(IPVER<<4 | sizeof(ipHeader)/sizeof(unsigned long));
    ipHeader.tos=(UCHAR)0;
    ipHeader.total_len=htons((unsigned short)sizeof(ipHeader)+sizeof(tcpHeader)+sizeof(tcp_send_data));
    ipHeader.ident=0;       //16位标识
    ipHeader.frag_and_flags=0; //3位标志位
    ipHeader.ttl=128; //8位生存时间
    ipHeader.proto=IPPROTO_TCP; //协议类型
    ipHeader.checksum=0; //检验和暂时为0
    ipHeader.sourceIP=inet_addr(argv[1]);  //32位源IP地址
    ipHeader.destIP=inet_addr(argv[3]);    //32位目的IP地址

    //计算IP头部检验和
    memset(check_Buff,0,MAX_BUFF_LEN);
    memcpy(check_Buff,&ipHeader,sizeof(IP_HEADER));
    ipHeader.checksum=checksum(check_Buff,sizeof(IP_HEADER));

    //构造TCP伪首部
    psdHeader.saddr=ipHeader.sourceIP;
    psdHeader.daddr=ipHeader.destIP;
    psdHeader.mbz=0;
    psdHeader.ptcl=ipHeader.proto;
    psdHeader.tcpl=htons(sizeof(TCP_HEADER)+sizeof(tcp_send_data));

    //填充TCP首部
    tcpHeader.th_dport=htons(atoi(argv[4])); //16位目的端口号
    tcpHeader.th_sport=htons(atoi(argv[2])); //16位源端口号
    tcpHeader.th_seq=0;                         //SYN序列号
    tcpHeader.th_ack=0;                         //ACK序列号置为0
    //TCP长度和保留位
    tcpHeader.th_lenres=(sizeof(tcpHeader)/sizeof(unsigned long)<<4|0);
    tcpHeader.th_flag=2; //修改这里来实现不同的标志位探测，2是SYN，1是FIN，16是ACK探测 等等
    tcpHeader.th_win=htons((unsigned short)16384);     //窗口大小
    tcpHeader.th_urp=0;                                   //偏移大小   
    tcpHeader.th_sum=0;                                   //检验和暂时填为0
   
    //计算TCP校验和
    memset(check_Buff,0,MAX_BUFF_LEN);
    memcpy(check_Buff,&psdHeader,sizeof(psdHeader));
    memcpy(check_Buff+sizeof(psdHeader),&tcpHeader,sizeof(tcpHeader));
    memcpy(check_Buff+sizeof(PSD_HEADER)+sizeof(TCP_HEADER),tcp_send_data,sizeof(tcp_send_data));
    tcpHeader.th_sum=checksum(check_Buff,sizeof(PSD_HEADER)+sizeof(TCP_HEADER)+sizeof(tcp_send_data));

    //填充发送缓冲区
    memset(Sendto_Buff,0,MAX_BUFF_LEN);
    memcpy(Sendto_Buff,&ipHeader,sizeof(IP_HEADER));
    memcpy(Sendto_Buff+sizeof(IP_HEADER),&tcpHeader,sizeof(TCP_HEADER));
    memcpy(Sendto_Buff+sizeof(IP_HEADER)+sizeof(TCP_HEADER),tcp_send_data,sizeof(tcp_send_data));
    int datasize=sizeof(IP_HEADER)+sizeof(TCP_HEADER)+sizeof(tcp_send_data);
    //发送数据报的目的地址
    SOCKADDR_IN dest;   
    memset(&dest,0,sizeof(dest));
    dest.sin_family=AF_INET;
    dest.sin_addr.s_addr=inet_addr(argv[3]);
   // datasize=150;
    rect=sendto(sock,Sendto_Buff,datasize, 0,(struct sockaddr*)&dest, sizeof(dest));
    if (rect==SOCKET_ERROR)
    {  
        printf("send error!:%d\n",WSAGetLastError());
        return false;
    }
    else
    printf("send ok!\n");
    closesocket(sock);
    WSACleanup();

    return 0;
}