#include "StdAfx.h"
#include "ZBase64.h"
static const CHAR* DATA_BIN2ASCII = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

INT BASE64_Encode(const BYTE* inputBuffer, INT inputCount, TCHAR* outputBuffer)
{
	INT i;
	BYTE b0, b1, b2;

	if ((inputBuffer == NULL) || (inputCount < 0))
	{
		return -1;	// 参数错误
	}

	if (outputBuffer != NULL)
	{
		for (i = inputCount; i > 0; i -= 3)
		{
			if (i >= 3)
			{	// 将3字节数据转换成4个ASCII字符
				b0 = *inputBuffer++;
				b1 = *inputBuffer++;
				b2 = *inputBuffer++;

				*outputBuffer++ = DATA_BIN2ASCII[b0 >> 2];
				*outputBuffer++ = DATA_BIN2ASCII[((b0 << 4) | (b1 >> 4)) & 0x3F];
				*outputBuffer++ = DATA_BIN2ASCII[((b1 << 2) | (b2 >> 6)) & 0x3F];
				*outputBuffer++ = DATA_BIN2ASCII[b2 & 0x3F];
			}
			else
			{
				b0 = *inputBuffer++;
				if (i == 2)b1 = *inputBuffer++; else b1 = 0;

				*outputBuffer++ = DATA_BIN2ASCII[b0 >> 2];
				*outputBuffer++ = DATA_BIN2ASCII[((b0 << 4) | (b1 >> 4)) & 0x3F];
				*outputBuffer++ = (i == 1) ? TEXT('=') : DATA_BIN2ASCII[(b1 << 2) & 0x3F];
				*outputBuffer++ = TEXT('=');
			}
		} // End for i

		*outputBuffer++ = TEXT('/0');	// 添加字符串结束标记
	}

	return ((inputCount + 2) / 3) * 4;	// 返回有效字符个数
}

#define B64_EOLN			0xF0	// 换行/n
#define B64_CR				0xF1	// 回车/r
#define B64_EOF				0xF2	// 连字符-
#define B64_WS				0xE0	// 跳格或者空格（/t、space）
#define B64_ERROR       	0xFF	// 错误字符
#define B64_NOT_BASE64(a)	(((a)|0x13) == 0xF3)

static const BYTE DATA_ASCII2BIN[128] = {
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xE0, 0xF0, 0xFF, 0xFF, 0xF1, 0xFF, 0xFF,
	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xE0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x3E, 0xFF, 0xF2, 0xFF, 0x3F,
	0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0xFF, 0xFF, 0xFF, 0x00, 0xFF, 0xFF,
	0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
	0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
	0xFF, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
	0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};

INT BASE64_Decode(const TCHAR* inputBuffer, INT inputCount, BYTE* outputBuffer)
{
	INT i, j;
	BYTE b[4];
	TCHAR ch;

	if ((inputBuffer == NULL) || (inputCount < 0))
	{
		return -1;	// 参数错误
	}

	// 去除头部空白字符
	while (inputCount > 0)
	{
		ch = *inputBuffer;
		if ((ch < 0) || (ch >= 0x80))
		{
			return -2;	// 数据错误，不在ASCII字符编码范围内
		}
		else
		{
			if (DATA_ASCII2BIN[ch] == B64_WS)
			{
				inputBuffer++;
				inputCount--;
			}
			else
			{
				break;
			}
		}
	}

	// 去除尾部的空白字符、回车换行字符、连字符
	while (inputCount >= 4)
	{
		ch = inputBuffer[inputCount - 1];
		if ((ch < 0) || (ch >= 0x80))
		{
			return -2;	// 数据错误，不在ASCII字符编码范围内
		}
		else
		{
			if (B64_NOT_BASE64(DATA_ASCII2BIN[ch]))
			{
				inputCount--;
			}
			else
			{
				break;
			}
		}
	}

	// 字符串长度必须为4的倍数
	if ((inputCount % 4) != 0)
	{
		return -2;	// 数据错误
	}

	if (outputBuffer != NULL)
	{
		for (i = 0; i < inputCount; i += 4)
		{
			for (j = 0; j < 4; j++)
			{
				ch = *inputBuffer++;
				if ((ch < 0) || (ch >= 0x80))
				{
					return -2;	// 数据错误，不在ASCII字符编码范围内
				}
				else
				{
					if (ch == '=')	// 发现BASE64编码中的填充字符
					{
						break;
					}
					else
					{
						b[j] = DATA_ASCII2BIN[ch];
						if (b[j] & 0x80)
						{
							return -2;	// 数据错误，无效的Base64编码字符
						}
					}
				}
			} // End for j

			if (j == 4)
			{
				*outputBuffer++ = (b[0] << 2) | (b[1] >> 4);
				*outputBuffer++ = (b[1] << 4) | (b[2] >> 2);
				*outputBuffer++ = (b[2] << 6) | b[3];
			}
			else if (j == 3)
			{	// 有1个填充字节
				*outputBuffer++ = (b[0] << 2) | (b[1] >> 4);
				*outputBuffer++ = (b[1] << 4) | (b[2] >> 2);

				return (i >> 2) * 3 + 2;
			}
			else if (j == 2)
			{	// 有2个填充字节
				*outputBuffer++ = (b[0] << 2) | (b[1] >> 4);

				return (i >> 2) * 3 + 1;
			}
			else
			{
				return -2;	// 数据错误，无效的Base64编码字符
			}
		}	// End for i
	}

	return (inputCount >> 2) * 3;
}