/*
 * MD5 hashing code copied from Lepton's crack <http://usuarios.lycos.es/reinob/>
 *
 * Adapted to be API-compatible with the previous (GPL-incompatible) code.
 */

/*
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.  This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */

#include <sys/types.h>
#include <string.h>		/* for memcpy() */
#include <stdio.h>
#include "md5.h"

static void md5_transform(uint32_t buf[4], uint32_t const in[16]);

/*
 * Wrapper function for all-in-one MD5
 *
 * Bernardo Reino, aka Lepton.
 * 20021120
 */

/* Turns out MD5 was designed for little-endian machines. If we're running
   on a big-endian machines, we have to swap some bytes. Since detecting
   endianness at compile time reliably seems pretty hard, let's do it at
   run-time. It's not like we're going to checksum megabytes of data... */
static uint32_t cvt32(uint32_t val)
{
	static int little_endian = -1;
	
	if (little_endian == -1)
	{
		little_endian = 1;
		little_endian = *((char*) &little_endian);
	}
	
	if (little_endian)
		return val;
	else
		return (val >> 24) |
		       ((val >> 8) & 0xff00) |
		       ((val << 8) & 0xff0000) |
		       (val << 24);
}

void md5_init(struct MD5Context *ctx)
{
	ctx->buf[0] = 0x67452301;
	ctx->buf[1] = 0xefcdab89;
	ctx->buf[2] = 0x98badcfe;
	ctx->buf[3] = 0x10325476;

	ctx->bits[0] = 0;
	ctx->bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void md5_append(struct MD5Context *ctx, const md5_byte_t *buf,
		unsigned int len)
{
	uint32_t t;

	/* Update bitcount */

	t = ctx->bits[0];
	if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
		ctx->bits[1]++;	/* Carry from low to high */
	ctx->bits[1] += len >> 29;

	t = (t >> 3) & 0x3f;	/* Bytes already in shsInfo->data */

	/* Handle any leading odd-sized chunks */

	if (t) {
		unsigned char *p = (unsigned char *) ctx->in + t;

		t = 64 - t;
		if (len < t) {
			memcpy(p, buf, len);
			return;
		}
		memcpy(p, buf, t);
		md5_transform(ctx->buf, (uint32_t *) ctx->in);
		buf += t;
		len -= t;
	}
	/* Process data in 64-byte chunks */

	while (len >= 64) {
		memcpy(ctx->in, buf, 64);
		md5_transform(ctx->buf, (uint32_t *) ctx->in);
		buf += 64;
		len -= 64;
	}

	/* Handle any remaining bytes of data. */

	memcpy(ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void md5_finish(struct MD5Context *ctx, md5_byte_t digest[16])
{
	unsigned count;
	unsigned char *p;

	/* Compute number of bytes mod 64 */
	count = (ctx->bits[0] >> 3) & 0x3F;

	/* Set the first char of padding to 0x80.  This is safe since there is
	   always at least one byte free */
	p = ctx->in + count;
	*p++ = 0x80;

	/* Bytes of padding needed to make 64 bytes */
	count = 64 - 1 - count;

	/* Pad out to 56 mod 64 */
	if (count < 8) {
		/* Two lots of padding:  Pad the first block to 64 bytes */
		memset(p, 0, count);
		md5_transform(ctx->buf, (uint32_t *) ctx->in);

		/* Now fill the next block with 56 bytes */
		memset(ctx->in, 0, 56);
	} else {
		/* Pad block to 56 bytes */
		memset(p, 0, count - 8);
	}

	/* Append length in bits and transform */
	((uint32_t *) ctx->in)[14] = cvt32(ctx->bits[0]);
	((uint32_t *) ctx->in)[15] = cvt32(ctx->bits[1]);

	md5_transform(ctx->buf, (uint32_t *) ctx->in);
	ctx->buf[0] = cvt32(ctx->buf[0]);
	ctx->buf[1] = cvt32(ctx->buf[1]);
	ctx->buf[2] = cvt32(ctx->buf[2]);
	ctx->buf[3] = cvt32(ctx->buf[3]);
	memcpy(digest, ctx->buf, 16);
	memset(ctx, 0, sizeof(ctx));	/* In case it's sensitive */
}

void md5_finish_ascii(struct MD5Context *context, char *ascii)
{
	md5_byte_t bin[16];
	int i;
	
	md5_finish(context, bin);
	for (i = 0; i < 16; i ++)
		sprintf(ascii + i * 2, "%02x", bin[i]);
}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void md5_transform(uint32_t buf[4], uint32_t const in[16])
{
	register uint32_t a, b, c, d;

	a = buf[0];
	b = buf[1];
	c = buf[2];
	d = buf[3];

	MD5STEP(F1, a, b, c, d, cvt32(in[0]) + 0xd76aa478, 7);
	MD5STEP(F1, d, a, b, c, cvt32(in[1]) + 0xe8c7b756, 12);
	MD5STEP(F1, c, d, a, b, cvt32(in[2]) + 0x242070db, 17);
	MD5STEP(F1, b, c, d, a, cvt32(in[3]) + 0xc1bdceee, 22);
	MD5STEP(F1, a, b, c, d, cvt32(in[4]) + 0xf57c0faf, 7);
	MD5STEP(F1, d, a, b, c, cvt32(in[5]) + 0x4787c62a, 12);
	MD5STEP(F1, c, d, a, b, cvt32(in[6]) + 0xa8304613, 17);
	MD5STEP(F1, b, c, d, a, cvt32(in[7]) + 0xfd469501, 22);
	MD5STEP(F1, a, b, c, d, cvt32(in[8]) + 0x698098d8, 7);
	MD5STEP(F1, d, a, b, c, cvt32(in[9]) + 0x8b44f7af, 12);
	MD5STEP(F1, c, d, a, b, cvt32(in[10]) + 0xffff5bb1, 17);
	MD5STEP(F1, b, c, d, a, cvt32(in[11]) + 0x895cd7be, 22);
	MD5STEP(F1, a, b, c, d, cvt32(in[12]) + 0x6b901122, 7);
	MD5STEP(F1, d, a, b, c, cvt32(in[13]) + 0xfd987193, 12);
	MD5STEP(F1, c, d, a, b, cvt32(in[14]) + 0xa679438e, 17);
	MD5STEP(F1, b, c, d, a, cvt32(in[15]) + 0x49b40821, 22);

	MD5STEP(F2, a, b, c, d, cvt32(in[1]) + 0xf61e2562, 5);
	MD5STEP(F2, d, a, b, c, cvt32(in[6]) + 0xc040b340, 9);
	MD5STEP(F2, c, d, a, b, cvt32(in[11]) + 0x265e5a51, 14);
	MD5STEP(F2, b, c, d, a, cvt32(in[0]) + 0xe9b6c7aa, 20);
	MD5STEP(F2, a, b, c, d, cvt32(in[5]) + 0xd62f105d, 5);
	MD5STEP(F2, d, a, b, c, cvt32(in[10]) + 0x02441453, 9);
	MD5STEP(F2, c, d, a, b, cvt32(in[15]) + 0xd8a1e681, 14);
	MD5STEP(F2, b, c, d, a, cvt32(in[4]) + 0xe7d3fbc8, 20);
	MD5STEP(F2, a, b, c, d, cvt32(in[9]) + 0x21e1cde6, 5);
	MD5STEP(F2, d, a, b, c, cvt32(in[14]) + 0xc33707d6, 9);
	MD5STEP(F2, c, d, a, b, cvt32(in[3]) + 0xf4d50d87, 14);
	MD5STEP(F2, b, c, d, a, cvt32(in[8]) + 0x455a14ed, 20);
	MD5STEP(F2, a, b, c, d, cvt32(in[13]) + 0xa9e3e905, 5);
	MD5STEP(F2, d, a, b, c, cvt32(in[2]) + 0xfcefa3f8, 9);
	MD5STEP(F2, c, d, a, b, cvt32(in[7]) + 0x676f02d9, 14);
	MD5STEP(F2, b, c, d, a, cvt32(in[12]) + 0x8d2a4c8a, 20);

	MD5STEP(F3, a, b, c, d, cvt32(in[5]) + 0xfffa3942, 4);
	MD5STEP(F3, d, a, b, c, cvt32(in[8]) + 0x8771f681, 11);
	MD5STEP(F3, c, d, a, b, cvt32(in[11]) + 0x6d9d6122, 16);
	MD5STEP(F3, b, c, d, a, cvt32(in[14]) + 0xfde5380c, 23);
	MD5STEP(F3, a, b, c, d, cvt32(in[1]) + 0xa4beea44, 4);
	MD5STEP(F3, d, a, b, c, cvt32(in[4]) + 0x4bdecfa9, 11);
	MD5STEP(F3, c, d, a, b, cvt32(in[7]) + 0xf6bb4b60, 16);
	MD5STEP(F3, b, c, d, a, cvt32(in[10]) + 0xbebfbc70, 23);
	MD5STEP(F3, a, b, c, d, cvt32(in[13]) + 0x289b7ec6, 4);
	MD5STEP(F3, d, a, b, c, cvt32(in[0]) + 0xeaa127fa, 11);
	MD5STEP(F3, c, d, a, b, cvt32(in[3]) + 0xd4ef3085, 16);
	MD5STEP(F3, b, c, d, a, cvt32(in[6]) + 0x04881d05, 23);
	MD5STEP(F3, a, b, c, d, cvt32(in[9]) + 0xd9d4d039, 4);
	MD5STEP(F3, d, a, b, c, cvt32(in[12]) + 0xe6db99e5, 11);
	MD5STEP(F3, c, d, a, b, cvt32(in[15]) + 0x1fa27cf8, 16);
	MD5STEP(F3, b, c, d, a, cvt32(in[2]) + 0xc4ac5665, 23);

	MD5STEP(F4, a, b, c, d, cvt32(in[0]) + 0xf4292244, 6);
	MD5STEP(F4, d, a, b, c, cvt32(in[7]) + 0x432aff97, 10);
	MD5STEP(F4, c, d, a, b, cvt32(in[14]) + 0xab9423a7, 15);
	MD5STEP(F4, b, c, d, a, cvt32(in[5]) + 0xfc93a039, 21);
	MD5STEP(F4, a, b, c, d, cvt32(in[12]) + 0x655b59c3, 6);
	MD5STEP(F4, d, a, b, c, cvt32(in[3]) + 0x8f0ccc92, 10);
	MD5STEP(F4, c, d, a, b, cvt32(in[10]) + 0xffeff47d, 15);
	MD5STEP(F4, b, c, d, a, cvt32(in[1]) + 0x85845dd1, 21);
	MD5STEP(F4, a, b, c, d, cvt32(in[8]) + 0x6fa87e4f, 6);
	MD5STEP(F4, d, a, b, c, cvt32(in[15]) + 0xfe2ce6e0, 10);
	MD5STEP(F4, c, d, a, b, cvt32(in[6]) + 0xa3014314, 15);
	MD5STEP(F4, b, c, d, a, cvt32(in[13]) + 0x4e0811a1, 21);
	MD5STEP(F4, a, b, c, d, cvt32(in[4]) + 0xf7537e82, 6);
	MD5STEP(F4, d, a, b, c, cvt32(in[11]) + 0xbd3af235, 10);
	MD5STEP(F4, c, d, a, b, cvt32(in[2]) + 0x2ad7d2bb, 15);
	MD5STEP(F4, b, c, d, a, cvt32(in[9]) + 0xeb86d391, 21);

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