/**
 * 包構造模塊
 */
#include "stdafx.h"
#include <stdio.h>
#include "crypt.h"
#include "md5.h"
#include <stdlib.h>
#include <string.h>
#include "options.h"


/**
 *	在數據流當前位置(p)開始增加一個 (type,len,data) 三元組
 *
 *	返回指向下一個位置的指針
 */
static inline unsigned char *add_item(unsigned char *p,unsigned char type,void *buf,int len)
{
	*p++ = type;
	*p++ = 2 + len;
	memcpy(p,buf,len);
	p+=len;

	return p;
}


/**
 *	構造一個 ping 協議報文
 *
 *	@param size packet 緩沖區長度
 *	@return 返回構造出的報文長度
 *	@note 未檢查是否構造越過 packet 邊界
 */
int packet_ping(unsigned char *packet,int size)
{
	unsigned char *p;

	p = packet;
	*p++ = 3;
	p += 16 + 1;


	p = add_item(p,7,g_options.my_mac,sizeof(g_options.my_mac));

	p = add_item(p,8,g_options.session,g_options.sesslen);

	p = add_item(p,9,(void*)g_options.my_ip,strlen(g_options.my_ip));


	size = p - packet;
	p = packet + 1;
	*p++ = size;
	memset(p,0,16);
	MD5(p,packet,size);
	encrypt(packet,size);
	
	return size;
}


/**
 *	構造一個 login 協議報文
 *
 *	@param size packet 緩沖區長度
 *	@return 返回構造出的報文長度
 *	@note 未檢查是否構造越過 packet 邊界
 */
int packet_login(unsigned char *packet,int size)
{
	unsigned char c = 1;
	unsigned char *p;

	p = packet;
	*p++ = 1;
	p += 16 + 1;

	p = add_item(p,1,(void*)g_options.username,strlen(g_options.username));

	p = add_item(p,2,(void*)g_options.password,strlen(g_options.password));

	p = add_item(p,7,(void*)g_options.my_mac,sizeof(g_options.my_mac));

	p = add_item(p,9,(void*)g_options.my_ip,strlen(g_options.my_ip));

	p = add_item(p,0x0A,(void*)g_options.services,strlen(g_options.services));

	p = add_item(p,0x1F,(void*)g_options.version,strlen(g_options.version));

	p = add_item(p,0x20,(void*)&c,1);
	
	size = p - packet;
	p = packet + 1;
	*p++ = size;
	memset(p,0,16);
	MD5(p,packet,size);
	encrypt(packet,size);
	
	return size;	
}