#include <Winsock2.h>
#include <stdio.h>

struct rc4_state
{
	int x, y, m[256];
};

void rc4_setup( struct rc4_state *s, unsigned char *key,  int length );
void rc4_crypt( struct rc4_state *s, unsigned char *data, int length );

void main()
{
	struct rc4_state s;
    unsigned char key[]={0x01,0x02,0x03,0x04,0x05,0x06};//種子密鑰

	WORD wVersionRequested;
	WSADATA wsaData;
	int err;
	wVersionRequested = MAKEWORD( 1, 1 );//版本號1.1
//1.加載套接字庫	
	err = WSAStartup( wVersionRequested, &wsaData );
	if ( err != 0 ) {
		return;	}//endof if
	//判斷是否我們請求的winsocket版本，如果不是
	//則調用WSACleanup終止winsocket的使用并返回
	if ( LOBYTE( wsaData.wVersion ) != 1 ||
        HIBYTE( wsaData.wVersion ) != 1 ) {
		WSACleanup( );
		return; 	}///endof if
//2.創建套接字
	SOCKET sockClient = socket (AF_INET, SOCK_STREAM, 0);
//3.連接服務器端，無須綁定
	SOCKADDR_IN addrSrv;
	addrSrv.sin_addr.S_un.S_addr = inet_addr("222.28.142.146");
		//設定服務器端IP地址，"127.0.0.1"是本地回路地址
		//不管本地主機上有沒有網卡，都可以用這個IP測試網絡
	addrSrv.sin_family = AF_INET;
	addrSrv.sin_port = htons(6000); //端口號要與服務器端保持一致
	connect(sockClient,(SOCKADDR *)&addrSrv,sizeof(SOCKADDR));
//4.接收服務器端發送的數據,并且向服務器端發送數據
	char recvBuf[100];
	recv(sockClient,recvBuf,100,0);
	
	rc4_setup( &s, key, sizeof(key) );//生成加密子密鑰序列
	rc4_crypt( &s,(unsigned char *)recvBuf,sizeof(recvBuf));//用加密子密鑰序列解密數據

	printf("%s \n", recvBuf);

	char sendBuf[100];
	sprintf(sendBuf,"I'm teshore");

	rc4_setup( &s, key, sizeof(key) );//生成加密子密鑰序列
	rc4_crypt( &s,(unsigned char *)sendBuf,sizeof(sendBuf));//用加密子密鑰序列解密數據

	send(sockClient,sendBuf,strlen(sendBuf)+1,0);


//5.關閉套接字，釋放資源,并且終止對套接字庫的使用
	closesocket(sockClient);
	WSACleanup();
}//endof main()

//函數功能：由給定的種子密鑰生成子密鑰
void rc4_setup( struct rc4_state *s, unsigned char *key,  int length )
{
	int i, j, k, *m, a;

	s->x = 0;
	s->y = 0;
	m = s->m;

	for( i = 0; i < 256; i++ )
	{
		m[i] = i;
	}

	j = k = 0;

	for( i = 0; i < 256; i++ )
	{
		a = m[i];
		j = (unsigned char) ( j + a + key[k] );
		m[i] = m[j]; m[j] = a;
		if( ++k >= length ) k = 0;
	}
}
//函數功能：由生成的子密鑰加解密數據
void rc4_crypt( struct rc4_state *s, unsigned char *data, int length )
{ 
	int i, x, y, *m, a, b;

	x = s->x;
	y = s->y;
	m = s->m;

	for( i = 0; i < length; i++ )
	{
		x = (unsigned char) ( x + 1 ); a = m[x];
		y = (unsigned char) ( y + a );
		m[x] = b = m[y];
		m[y] = a;
		data[i] ^= m[(unsigned char) ( a + b )];
	}

	s->x = x;
	s->y = y;
}