#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>

typedef unsigned int uint32_t; 
typedef unsigned long long uint64_t;
//字节序的小头和大头的问题
#define LITTLE_ENDIAN  0x0123
#define BIG_ENDIAN     0x3210

//目前所有的代码都是为了小头党服务的，不知道有生之年这套代码是否还会为大头党服务一次？
#ifndef BYTES_ORDER
#define BYTES_ORDER    LITTLE_ENDIAN
#endif

#ifndef SWAP_UINT16
#define SWAP_UINT16(x)  ((((x) & 0xff00) >>  8) | (((x) & 0x00ff) <<  8))
#endif
#ifndef SWAP_UINT32
#define SWAP_UINT32(x)  ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
	(((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
#endif
#ifndef SWAP_UINT64
#define SWAP_UINT64(x)  ((((x) & 0xff00000000000000) >> 56) | (((x) & 0x00ff000000000000) >>  40) | \
	(((x) & 0x0000ff0000000000) >> 24) | (((x) & 0x000000ff00000000) >>  8) | \
	(((x) & 0x00000000ff000000) << 8 ) | (((x) & 0x0000000000ff0000) <<  24) | \
	(((x) & 0x000000000000ff00) << 40 ) | (((x) & 0x00000000000000ff) <<  56))
#endif

//将一个（字符串）数组，拷贝到另外一个uint32_t数组，同时每个uint32_t反字节序
void *swap_uint32_memcpy(void *to, const void *from, size_t length)
{
	memcpy(to, from, length);
	size_t remain_len =  (4 - (length & 3)) & 3;

	//数据不是4字节的倍数,补充0
	if (remain_len)
	{
		for (size_t i = 0; i < remain_len; ++i)
		{
			*((char *)(to) + length + i) = 0;
		}
		//调整成4的倍数
		length += remain_len;
	}

	//所有的数据反转
	for (size_t i = 0; i < length / 4; ++i)
	{
		((uint32_t *)to)[i] = SWAP_UINT32(((uint32_t *)to)[i]);
	}

	return to;
}

///MD5的结果数据长度
static const size_t MD5_HASH_SIZE   = 16;
///SHA1的结果数据长度
static const size_t SHA1_HASH_SIZE  = 20;



namespace uselib
{


	/*!
	@brief      求某个内存块的MD5，
	@return     unsigned char* 返回的的结果，
	@param[in]  buf    求MD5的内存BUFFER指针
	@param[in]  size   BUFFER长度
	@param[out] result 结果
	*/
	unsigned char *md5(const unsigned char *buf,
		size_t size,
		unsigned char result[MD5_HASH_SIZE]);


	/*!
	@brief      求内存块BUFFER的SHA1值
	@return     unsigned char* 返回的的结果
	@param[in]  buf    求SHA1的内存BUFFER指针
	@param[in]  size   BUFFER长度
	@param[out] result 结果
	*/
	unsigned char *sha1(const unsigned char *buf,
		size_t size,
		unsigned char result[SHA1_HASH_SIZE]);
};


//================================================================================================
//MD5的算法

//每次处理的BLOCK的大小
static const size_t MD5_BLOCK_SIZE = 64;

//md5算法的上下文，保存一些状态，中间数据，结果
typedef struct md5_ctx
{
	//处理的数据的长度
	uint64_t length_;
	//还没有处理的数据长度
	uint64_t unprocessed_;
	//取得的HASH结果（中间数据）
	uint32_t  hash_[4];
} md5_ctx;


#define ROTL32(dword, n) ((dword) << (n) ^ ((dword) >> (32 - (n))))
#define ROTR32(dword, n) ((dword) >> (n) ^ ((dword) << (32 - (n))))
#define ROTL64(qword, n) ((qword) << (n) ^ ((qword) >> (64 - (n))))
#define ROTR64(qword, n) ((qword) >> (n) ^ ((qword) << (64 - (n))))


/*!
@brief      内部函数，初始化MD5的context，内容
@param      ctx
*/
static void md5_init(md5_ctx *ctx)
{
	ctx->length_ = 0;
	ctx->unprocessed_ = 0;

	/* initialize state */
	ctx->hash_[0] = 0x67452301;
	ctx->hash_[1] = 0xefcdab89;
	ctx->hash_[2] = 0x98badcfe;
	ctx->hash_[3] = 0x10325476;
}

/* First, define four auxiliary functions that each take as input
* three 32-bit words and returns a 32-bit word.*/

/* F(x,y,z) = ((y XOR z) AND x) XOR z - is faster then original version */
#define MD5_F(x, y, z) ((((y) ^ (z)) & (x)) ^ (z))
#define MD5_G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define MD5_H(x, y, z) ((x) ^ (y) ^ (z))
#define MD5_I(x, y, z) ((y) ^ ((x) | (~z)))

/* transformations for rounds 1, 2, 3, and 4. */
#define MD5_ROUND1(a, b, c, d, x, s, ac) { \
	(a) += MD5_F((b), (c), (d)) + (x) + (ac); \
	(a) = ROTL32((a), (s)); \
	(a) += (b); \
}
#define MD5_ROUND2(a, b, c, d, x, s, ac) { \
	(a) += MD5_G((b), (c), (d)) + (x) + (ac); \
	(a) = ROTL32((a), (s)); \
	(a) += (b); \
}
#define MD5_ROUND3(a, b, c, d, x, s, ac) { \
	(a) += MD5_H((b), (c), (d)) + (x) + (ac); \
	(a) = ROTL32((a), (s)); \
	(a) += (b); \
}
#define MD5_ROUND4(a, b, c, d, x, s, ac) { \
	(a) += MD5_I((b), (c), (d)) + (x) + (ac); \
	(a) = ROTL32((a), (s)); \
	(a) += (b); \
}


/*!
@brief      内部函数，将64个字节，16个uint32_t的数组进行摘要（杂凑）处理，处理的数据自己序是小头数据
@param      state 存放处理的hash数据结果
@param      block 要处理的block，64个字节，16个uint32_t的数组
*/
static void md5_process_block(uint32_t state[4], const uint32_t block[MD5_BLOCK_SIZE / 4])
{
	register unsigned a, b, c, d;
	a = state[0];
	b = state[1];
	c = state[2];
	d = state[3];

	const uint32_t *x = NULL;

	//MD5里面计算的数据都是小头数据.大头党的数据要处理
#if BYTES_ORDER == LITTLE_ENDIAN
	x = block;
#else
	uint32_t swap_block[MD5_BLOCK_SIZE / 4];
	swap_uint32_memcpy(swap_block, block, 64);
	x = swap_block;
#endif


	MD5_ROUND1(a, b, c, d, x[ 0],  7, 0xd76aa478);
	MD5_ROUND1(d, a, b, c, x[ 1], 12, 0xe8c7b756);
	MD5_ROUND1(c, d, a, b, x[ 2], 17, 0x242070db);
	MD5_ROUND1(b, c, d, a, x[ 3], 22, 0xc1bdceee);
	MD5_ROUND1(a, b, c, d, x[ 4],  7, 0xf57c0faf);
	MD5_ROUND1(d, a, b, c, x[ 5], 12, 0x4787c62a);
	MD5_ROUND1(c, d, a, b, x[ 6], 17, 0xa8304613);
	MD5_ROUND1(b, c, d, a, x[ 7], 22, 0xfd469501);
	MD5_ROUND1(a, b, c, d, x[ 8],  7, 0x698098d8);
	MD5_ROUND1(d, a, b, c, x[ 9], 12, 0x8b44f7af);
	MD5_ROUND1(c, d, a, b, x[10], 17, 0xffff5bb1);
	MD5_ROUND1(b, c, d, a, x[11], 22, 0x895cd7be);
	MD5_ROUND1(a, b, c, d, x[12],  7, 0x6b901122);
	MD5_ROUND1(d, a, b, c, x[13], 12, 0xfd987193);
	MD5_ROUND1(c, d, a, b, x[14], 17, 0xa679438e);
	MD5_ROUND1(b, c, d, a, x[15], 22, 0x49b40821);

	MD5_ROUND2(a, b, c, d, x[ 1],  5, 0xf61e2562);
	MD5_ROUND2(d, a, b, c, x[ 6],  9, 0xc040b340);
	MD5_ROUND2(c, d, a, b, x[11], 14, 0x265e5a51);
	MD5_ROUND2(b, c, d, a, x[ 0], 20, 0xe9b6c7aa);
	MD5_ROUND2(a, b, c, d, x[ 5],  5, 0xd62f105d);
	MD5_ROUND2(d, a, b, c, x[10],  9,  0x2441453);
	MD5_ROUND2(c, d, a, b, x[15], 14, 0xd8a1e681);
	MD5_ROUND2(b, c, d, a, x[ 4], 20, 0xe7d3fbc8);
	MD5_ROUND2(a, b, c, d, x[ 9],  5, 0x21e1cde6);
	MD5_ROUND2(d, a, b, c, x[14],  9, 0xc33707d6);
	MD5_ROUND2(c, d, a, b, x[ 3], 14, 0xf4d50d87);
	MD5_ROUND2(b, c, d, a, x[ 8], 20, 0x455a14ed);
	MD5_ROUND2(a, b, c, d, x[13],  5, 0xa9e3e905);
	MD5_ROUND2(d, a, b, c, x[ 2],  9, 0xfcefa3f8);
	MD5_ROUND2(c, d, a, b, x[ 7], 14, 0x676f02d9);
	MD5_ROUND2(b, c, d, a, x[12], 20, 0x8d2a4c8a);

	MD5_ROUND3(a, b, c, d, x[ 5],  4, 0xfffa3942);
	MD5_ROUND3(d, a, b, c, x[ 8], 11, 0x8771f681);
	MD5_ROUND3(c, d, a, b, x[11], 16, 0x6d9d6122);
	MD5_ROUND3(b, c, d, a, x[14], 23, 0xfde5380c);
	MD5_ROUND3(a, b, c, d, x[ 1],  4, 0xa4beea44);
	MD5_ROUND3(d, a, b, c, x[ 4], 11, 0x4bdecfa9);
	MD5_ROUND3(c, d, a, b, x[ 7], 16, 0xf6bb4b60);
	MD5_ROUND3(b, c, d, a, x[10], 23, 0xbebfbc70);
	MD5_ROUND3(a, b, c, d, x[13],  4, 0x289b7ec6);
	MD5_ROUND3(d, a, b, c, x[ 0], 11, 0xeaa127fa);
	MD5_ROUND3(c, d, a, b, x[ 3], 16, 0xd4ef3085);
	MD5_ROUND3(b, c, d, a, x[ 6], 23,  0x4881d05);
	MD5_ROUND3(a, b, c, d, x[ 9],  4, 0xd9d4d039);
	MD5_ROUND3(d, a, b, c, x[12], 11, 0xe6db99e5);
	MD5_ROUND3(c, d, a, b, x[15], 16, 0x1fa27cf8);
	MD5_ROUND3(b, c, d, a, x[ 2], 23, 0xc4ac5665);

	MD5_ROUND4(a, b, c, d, x[ 0],  6, 0xf4292244);
	MD5_ROUND4(d, a, b, c, x[ 7], 10, 0x432aff97);
	MD5_ROUND4(c, d, a, b, x[14], 15, 0xab9423a7);
	MD5_ROUND4(b, c, d, a, x[ 5], 21, 0xfc93a039);
	MD5_ROUND4(a, b, c, d, x[12],  6, 0x655b59c3);
	MD5_ROUND4(d, a, b, c, x[ 3], 10, 0x8f0ccc92);
	MD5_ROUND4(c, d, a, b, x[10], 15, 0xffeff47d);
	MD5_ROUND4(b, c, d, a, x[ 1], 21, 0x85845dd1);
	MD5_ROUND4(a, b, c, d, x[ 8],  6, 0x6fa87e4f);
	MD5_ROUND4(d, a, b, c, x[15], 10, 0xfe2ce6e0);
	MD5_ROUND4(c, d, a, b, x[ 6], 15, 0xa3014314);
	MD5_ROUND4(b, c, d, a, x[13], 21, 0x4e0811a1);
	MD5_ROUND4(a, b, c, d, x[ 4],  6, 0xf7537e82);
	MD5_ROUND4(d, a, b, c, x[11], 10, 0xbd3af235);
	MD5_ROUND4(c, d, a, b, x[ 2], 15, 0x2ad7d2bb);
	MD5_ROUND4(b, c, d, a, x[ 9], 21, 0xeb86d391);

	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
}


/*!
@brief      内部函数，处理数据的前面部分(>64字节的部分)，每次组成一个64字节的block就进行杂凑处理
@param[out] ctx  算法的context，用于记录一些处理的上下文和结果
@param[in]  buf  处理的数据，
@param[in]  size 处理的数据长度
*/
static void md5_update(md5_ctx *ctx, const unsigned char *buf, size_t size)
{
	//为什么不是=，因为在某些环境下，可以多次调用zen_md5_update，但这种情况，必须保证前面的调用，每次都没有unprocessed_
	ctx->length_ += size;

	//每个处理的块都是64字节
	while (size >= MD5_BLOCK_SIZE)
	{
		md5_process_block(ctx->hash_, reinterpret_cast<const uint32_t *>(buf));
		buf  += MD5_BLOCK_SIZE;
		size -= MD5_BLOCK_SIZE;
	}

	ctx->unprocessed_ = size;
}


/*!
@brief      内部函数，处理数据的末尾部分，我们要拼出最后1个（或者两个）要处理的BLOCK，加上0x80，加上长度进行处理
@param[in]  ctx    算法的context，用于记录一些处理的上下文和结果
@param[in]  buf    处理的数据
@param[in]  size   处理buffer的长度
@param[out] result 返回的结果，
*/
static void md5_final(md5_ctx *ctx, const unsigned char *buf, size_t size, unsigned char *result)
{
	uint32_t message[MD5_BLOCK_SIZE / 4];

	//保存剩余的数据，我们要拼出最后1个（或者两个）要处理的块，前面的算法保证了，最后一个块肯定小于64个字节
	if (ctx->unprocessed_)
	{
		memcpy(message, buf + size - ctx->unprocessed_, static_cast<size_t>( ctx->unprocessed_));
	}

	//得到0x80要添加在的位置（在uint32_t 数组中），
	uint32_t index = ((uint32_t)ctx->length_ & 63) >> 2;
	uint32_t shift = ((uint32_t)ctx->length_ & 3) * 8;

	//添加0x80进去，并且把余下的空间补充0
	message[index]   &= ~(0xFFFFFFFF << shift);
	message[index++] ^= 0x80 << shift;

	//如果这个block还无法处理，其后面的长度无法容纳长度64bit，那么先处理这个block
	if (index > 14)
	{
		while (index < 16)
		{
			message[index++] = 0;
		}

		md5_process_block(ctx->hash_, message);
		index = 0;
	}

	//补0
	while (index < 14)
	{
		message[index++] = 0;
	}

	//保存长度，注意是bit位的长度,这个问题让我看着郁闷了半天，
	uint64_t data_len = (ctx->length_) << 3;

	//注意MD5算法要求的64bit的长度是小头LITTLE-ENDIAN编码，注意下面的比较是!=
#if BYTES_ORDER != LITTLE_ENDIAN
	data_len = SWAP_UINT64(data_len);
#endif

	message[14] = (uint32_t) (data_len & 0x00000000FFFFFFFF);
	message[15] = (uint32_t) ((data_len & 0xFFFFFFFF00000000ULL) >> 32);

	md5_process_block(ctx->hash_, message);

	//注意结果是小头党的，在大头的世界要进行转换
#if BYTES_ORDER == LITTLE_ENDIAN
	memcpy(result, &ctx->hash_, MD5_HASH_SIZE);
#else
	swap_uint32_memcpy(result, &ctx->hash_, MD5_HASH_SIZE);
#endif

}


//计算一个内存数据的MD5值
unsigned char *uselib::md5(const unsigned char *buf,size_t size,unsigned char result[MD5_HASH_SIZE])
{
	assert(result != NULL);

	md5_ctx ctx;
	md5_init(&ctx);
	md5_update(&ctx, buf, size);
	md5_final(&ctx, buf, size, result);
	return result;
}




//================================================================================================
//SHA1的算法

//每次处理的BLOCK的大小
static const size_t SHA1_BLOCK_SIZE = 64;

//SHA1算法的上下文，保存一些状态，中间数据，结果
typedef struct sha1_ctx
{

	//处理的数据的长度
	uint64_t length_;
	//还没有处理的数据长度
	uint64_t unprocessed_;
	/* 160-bit algorithm internal hashing state */
	uint32_t hash_[5];
} sha1_ctx;

//内部函数，SHA1算法的上下文的初始化
static void sha1_init(sha1_ctx *ctx)
{
	ctx->length_ = 0;
	ctx->unprocessed_ = 0;
	// 初始化算法的几个常量，魔术数
	ctx->hash_[0] = 0x67452301;
	ctx->hash_[1] = 0xefcdab89;
	ctx->hash_[2] = 0x98badcfe;
	ctx->hash_[3] = 0x10325476;
	ctx->hash_[4] = 0xc3d2e1f0;
}


/*!
@brief      内部函数，对一个64bit内存块进行摘要(杂凑)处理，
@param      hash  存放计算hash结果的的数组
@param      block 要计算的处理得内存块
*/
static void sha1_process_block(uint32_t hash[5],const uint32_t block[SHA1_BLOCK_SIZE / 4])
{
	size_t        t;
	uint32_t      wblock[80];
	register uint32_t      a, b, c, d, e, temp;

	//SHA1算法处理的内部数据要求是大头党的，在小头的环境转换
#if BYTES_ORDER == LITTLE_ENDIAN
	swap_uint32_memcpy(wblock, block, SHA1_BLOCK_SIZE);
#else
	::memcpy(wblock, block, SHA1_BLOCK_SIZE);
#endif

	//处理
	for (t = 16; t < 80; t++)
	{
		wblock[t] = ROTL32(wblock[t - 3] ^ wblock[t - 8] ^ wblock[t - 14] ^ wblock[t - 16], 1);
	}

	a = hash[0];
	b = hash[1];
	c = hash[2];
	d = hash[3];
	e = hash[4];

	for (t = 0; t < 20; t++)
	{
		/* the following is faster than ((B & C) | ((~B) & D)) */
		temp =  ROTL32(a, 5) + (((c ^ d) & b) ^ d)
			+ e + wblock[t] + 0x5A827999;
		e = d;
		d = c;
		c = ROTL32(b, 30);
		b = a;
		a = temp;
	}

	for (t = 20; t < 40; t++)
	{
		temp = ROTL32(a, 5) + (b ^ c ^ d) + e + wblock[t] + 0x6ED9EBA1;
		e = d;
		d = c;
		c = ROTL32(b, 30);
		b = a;
		a = temp;
	}

	for (t = 40; t < 60; t++)
	{
		temp = ROTL32(a, 5) + ((b & c) | (b & d) | (c & d))
			+ e + wblock[t] + 0x8F1BBCDC;
		e = d;
		d = c;
		c = ROTL32(b, 30);
		b = a;
		a = temp;
	}

	for (t = 60; t < 80; t++)
	{
		temp = ROTL32(a, 5) + (b ^ c ^ d) + e + wblock[t] + 0xCA62C1D6;
		e = d;
		d = c;
		c = ROTL32(b, 30);
		b = a;
		a = temp;
	}

	hash[0] += a;
	hash[1] += b;
	hash[2] += c;
	hash[3] += d;
	hash[4] += e;
}


/*!
@brief      内部函数，处理数据的前面部分(>64字节的部分)，每次组成一个64字节的block就进行杂凑处理
@param      ctx  算法的上下文，记录中间数据，结果等
@param      msg  要进行计算的数据buffer
@param      size 长度
*/
static void sha1_update(sha1_ctx *ctx,const unsigned char *buf, size_t size)
{
	//为了让zen_sha1_update可以多次进入，长度可以累计
	ctx->length_ += size;

	//每个处理的块都是64字节
	while (size >= SHA1_BLOCK_SIZE)
	{
		sha1_process_block(ctx->hash_, reinterpret_cast<const uint32_t *>(buf));
		buf  += SHA1_BLOCK_SIZE;
		size -= SHA1_BLOCK_SIZE;
	}

	ctx->unprocessed_ = size;
}


/*!
@brief      内部函数，处理数据的最后部分，添加0x80,补0，增加长度信息
@param      ctx    算法的上下文，记录中间数据，结果等
@param      msg    要进行计算的数据buffer
@param      result 返回的结果
*/
static void sha1_final(sha1_ctx *ctx, const unsigned char *msg,size_t size, unsigned char *result)
{

	uint32_t message[SHA1_BLOCK_SIZE / 4];

	//保存剩余的数据，我们要拼出最后1个（或者两个）要处理的块，前面的算法保证了，最后一个块肯定小于64个字节
	if (ctx->unprocessed_)
	{
		memcpy(message, msg + size - ctx->unprocessed_, static_cast<size_t>( ctx->unprocessed_));
	}

	//得到0x80要添加在的位置（在uint32_t 数组中），
	uint32_t index = ((uint32_t)ctx->length_ & 63) >> 2;
	uint32_t shift = ((uint32_t)ctx->length_ & 3) * 8;

	//添加0x80进去，并且把余下的空间补充0
	message[index]   &= ~(0xFFFFFFFF << shift);
	message[index++] ^= 0x80 << shift;

	//如果这个block还无法处理，其后面的长度无法容纳长度64bit，那么先处理这个block
	if (index > 14)
	{
		while (index < 16)
		{
			message[index++] = 0;
		}

		sha1_process_block(ctx->hash_, message);
		index = 0;
	}

	//补0
	while (index < 14)
	{
		message[index++] = 0;
	}

	//保存长度，注意是bit位的长度,这个问题让我看着郁闷了半天，
	uint64_t data_len = (ctx->length_) << 3;

	//注意SHA1算法要求的64bit的长度是大头BIG-ENDIAN，在小头的世界要进行转换
#if BYTES_ORDER == LITTLE_ENDIAN
	data_len = SWAP_UINT64(data_len);
#endif

	message[14] = (uint32_t) (data_len & 0x00000000FFFFFFFF);
	message[15] = (uint32_t) ((data_len & 0xFFFFFFFF00000000ULL) >> 32);

	sha1_process_block(ctx->hash_, message);

	//注意结果是大头党的，在小头的世界要进行转换
#if BYTES_ORDER == LITTLE_ENDIAN
	swap_uint32_memcpy(result, &ctx->hash_, SHA1_HASH_SIZE);
#else
	memcpy(result, &ctx->hash_, SHA1_HASH_SIZE);
#endif
}



//计算一个内存数据的SHA1值
unsigned char *uselib::sha1(const unsigned char *msg,size_t size,unsigned char result[SHA1_HASH_SIZE])
{
	assert(result != NULL);

	sha1_ctx ctx;
	sha1_init(&ctx);
	sha1_update(&ctx, msg, size);
	sha1_final(&ctx, msg, size, result);
	return result;
}