#include "stdio.h"
#include "alt_types.h"


void IP_TCP(void)       //tcp協議處理程序
{

   TCP_Symbol_Receive=Receive_Buffer[Start_TCP+13]&0x3f;  //接收到的TCP標志
   //printf("\nTCP_Symbole_Receive = 0x%4x\n",TCP_Symbol_Receive);

   /*
   0x01   FIN   發端完成發送任務
   0x02   SYN   同步序號用來發起一個連接
   0x04   RST   重建連接
   0x08   PSH   接收方應該盡快將這個報文段交給應用層
   0x10   ACK   確認序號有效
   0x20   URG   緊急指針(urgent pointer)有效*/

   TCP_Port_O=Receive_Buffer[Start_TCP+0]*256+Receive_Buffer[Start_TCP+1];  //外部端口號
   TCP_Port  =Receive_Buffer[Start_TCP+2]*256+Receive_Buffer[Start_TCP+3];  //本地端口號

   TCP_ISN_O =Change_UCHAR_UINT(Receive_Buffer,Start_TCP+4);   //外部ISN
   //printf("TCP_ISN_O =%u\n",TCP_ISN_O);

   TCP_ISN_OA=Change_UCHAR_UINT(Receive_Buffer,Start_TCP+8);   //外部確認ISN


   Receive_PACK_HTTP_Len=Receive_Buffer[Start_IP+2]*0x100+Receive_Buffer[Start_IP+3]-(Receive_Buffer[Start_TCP+12]/0x10)*4-20;

   switch(TCP_State)
   {
      case 0:  //初始狀態，等待被動連接
         if((TCP_Symbol_Receive&0x02)==0x02)  //Symbol = SYN
         {
            TCP_ISN_A=TCP_ISN_O+1;
            TCP_Symbol_Send=0x12;   //SYN，ACK
            Send_TCP_PACK();    //Send SYN,ACK 發送被動連接的第2次握手信號
            TCP_ISN++;
            TCP_State=1;
         }
         break;
      case 1:  //等待被動連接的第3次握手
         if((TCP_Symbol_Receive&0x10)==0x10)  //Symbol = ACK
            //if(TCP_ISN_OA==ISN);  //被動連接第3次握手信號有效
            TCP_State=2;
         break;
      case 2:  //正常傳輸狀態，或等待被動斷開
         if((TCP_Symbol_Receive&0x01)==0x01)  //Symbol = FIN
         {
            TCP_ISN_A=TCP_ISN_O+1;
            TCP_Symbol_Send=0x10;  //ASK
            Send_TCP_PACK();  //發送被動斷開的第2次握手信號

            TCP_Symbol_Send=0x11;  //?  似乎可以改成0x01
            Send_TCP_PACK();  //發送被動斷開的第3次握手信號
            TCP_ISN++;

            TCP_State=3;
         }
         else
            //printf("調用應用處理程序\n");
            if(TCP_Port==80)  //? 按照要求需要判斷http包是否是GET請求信號，不僅僅是判斷端口
            {
               APP_HTTP();    //調用HTTP處理程序
               //Send_HTTP_Response();  //發送HTTP的請求響應包
               //TCP_State=6;
            }
         break;
      case 3:   //在被動斷開情況下，等待第4次握手
         if((TCP_Symbol_Receive&0x10)==0x10)  //Symbol = ACK
            //if(TCP_ISN_OA==TCP_ISN);  //判斷被動斷開情況下，第4次握手是否有效
            TCP_State=0;
         break;
      case 4:  //在主動斷開情況下，等待第2次握手
         if((TCP_Symbol_Receive&0x10)==0x10)  //Symbol = ACK
            //if(TCP_ISN_OA==TCP_ISN);  //判斷主動斷開情況下，第2次握手信號是否有效
            TCP_State=5;
         break;
      case 5:  //在主動斷開情況下，等待第3次握手
         if((TCP_Symbol_Receive&0x01)==0x01)  //Symbol = FIN
         {
            TCP_ISN_A=TCP_ISN_O+1;
            TCP_Symbol_Send=0x10;  //ACK
            Send_TCP_PACK();  //在主動斷開情況下，發送第4次握手信號
            TCP_State=0;
         }
         break;
      case 6:  //等待HTTP響應的ACK
         if((TCP_Symbol_Receive&0x10)==0x10)  //Symbol = ACK
         {
            //if(TCP_ISN_OA==TCP_ISN);  //判斷http連接中，發送的http頭是否被收到
            Send_HTTP_Content();  //發送HTTP內容數據包
            TCP_State=7;
         }
         break;
      case 7:  //等待HTTP內容的ACK
         if((TCP_Symbol_Receive&0x10)==0x10)  //Symbol = ACK
         {
            //if(TCP_ISN_OA==TCP_ISN);  //判斷http連接中，發送的http內容是否被收到
            TCP_Symbol_Send=0x01;  //FIN
            TCP_ISN_A=TCP_ISN_O;
            Send_TCP_PACK();  //發送FIN數據包
            TCP_ISN++;
            TCP_State=4;
         }
         break;


   }
   //printf("TCP狀態  =  %d\n",TCP_State);
}

void Send_TCP_PACK(void)  //發送TCP連接用的標志數據包
{
   UINT Len=Start_TCP,Bogus_Len=0;
   UINT i,Head_Len,Data_SUM;
   UCHAR TCP_Bogus_Head[12];
   for(i=0;i<2;i++)
      Send_Buffer[Len++]=Receive_Buffer[Len+2];  //16位源端口號
   for(i=0;i<2;i++)
      Send_Buffer[Len++]=Receive_Buffer[Len-2];  //16位目的端口號

   Change_UINT_UCHAR(Send_Buffer,Len,TCP_ISN);  //32位序號
   Len+=4;

   Change_UINT_UCHAR(Send_Buffer,Len,TCP_ISN_A); //32位確認序號
   Len+=4;



   Send_Buffer[Len++]=Receive_Buffer[Len];  //4位首部長度和前4位保留
   //Send_Buffer[Len++]=0x70;
   //printf("首部長度<<4后的結果  =  %x",Receive_Buffer[Len]);
   Send_Buffer[Len++]=TCP_Symbol_Send;  //后2位保留，6個標志位

   for(i=0;i<2;i++)
      Send_Buffer[Len++]=Receive_Buffer[Len];  //16位窗口大小

   for(i=0;i<2;i++)
      Send_Buffer[Len++]=0;  //16位校驗和，先設置為0

   for(i=0;i<2;i++)
      Send_Buffer[Len++]=0;  //16位緊急指針

   Head_Len=(Receive_Buffer[Start_TCP+12]/0x10)*4;
   if(Head_Len>20)
      for(i=0;i<Head_Len-20;i++)
         Send_Buffer[Len++]=Receive_Buffer[Len];  //選項數據

   //設置TCP的偽首部
   for(i=0;i<4;i++)
      TCP_Bogus_Head[Bogus_Len++]=IP_Addr[i];
   for(i=0;i<4;i++)
      TCP_Bogus_Head[Bogus_Len++]=IP_O_Addr[i];
   TCP_Bogus_Head[Bogus_Len++]=0;
   TCP_Bogus_Head[Bogus_Len++]=6;
   TCP_Bogus_Head[Bogus_Len++]=Head_Len/0x100;
   TCP_Bogus_Head[Bogus_Len++]=Head_Len&0xff;

   Data_SUM=CHECK_SUM(TCP_Bogus_Head,0,12)&0xffff;       //偽首部的校驗和

   Data_SUM+=CHECK_SUM(Send_Buffer,Start_TCP,Head_Len)&0xffff; //TCP首部校驗和

   Data_SUM=(Data_SUM/0x10000)+(Data_SUM&0xffff);
   Data_SUM+=Data_SUM/0x10000;


   Send_Buffer[Start_TCP+16]=Data_SUM/0x100;
   Send_Buffer[Start_TCP+17]=Data_SUM&0xff;

   IP_PACK_Len=Head_Len+20;
   HEAD_IP();   //IP首部

   HEAD_Ethernet();   //以太網首部

   NET_Send_Packet(Send_Buffer,Len);  //發送數據包
}

void Change_UINT_UCHAR(UCHAR *Buffer,UINT Start,UINT Data)   //將一個32位的數據轉換成4個8位的數組
{
   Buffer[Start+0]=(Data/0x1000000)&0xff; //32位確認序號
   Buffer[Start+1]=(Data/0x10000)&0xff;
   Buffer[Start+2]=(Data/0x100)&0xff;
   Buffer[Start+3]=Data&0xff;
}

UINT Change_UCHAR_UINT(UCHAR *Buffer,UINT Start)   //數據轉換，將4個8位數組轉換成一個32位無符號整數
{
   UINT Data;
   Data =Buffer[Start+3];
   Data+=Buffer[Start+2]*0x100;
   Data+=Buffer[Start+1]*0x10000;
   Data+=Buffer[Start+0]*0x1000000;
   return Data;
}