/*
 * Copyright (C) 1993 Branko Lankester
 * Copyright (C) 1993 Colin Plumb
 * Copyright (C) 1995 Erik Troan
 * Copyright (C) 2004 John Ellis
 * Copyright (C) 2008 - 2016 The Geeqie Team
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 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 md5_init, call md5_update as
 * needed on buffers full of bytes, and then call md5_Final, which
 * will fill a supplied 16-byte array with the digest.
 */

#include <stdio.h>
#include <string.h>
#include "md5-util.h"


static void md5_transform(guint32 buf[4], const guint32 in[16]);

static gint _ie = 0x44332211;
static union _endian { gint i; gchar b[4]; } *_endian = (union _endian *)&_ie;
#define	IS_BIG_ENDIAN()		(_endian->b[0] == '\x44')
#define	IS_LITTLE_ENDIAN()	(_endian->b[0] == '\x11')


/*
 * Note: this code is harmless on little-endian machines.
 */
static void
_byte_reverse(guchar *buf, guint32 longs)
{
	guint32 t;
	do {
		t = (guint32) ((guint32) buf[3] << 8 | buf[2]) << 16 |
			((guint32) buf[1] << 8 | buf[0]);
		*(guint32 *) buf = t;
		buf += 4;
	} while (--longs);
}

/**
 * md5_init: Initialise an md5 context object
 * @ctx: md5 context
 *
 * Initialise an md5 buffer.
 *
 **/
void
md5_init(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;

	if (IS_BIG_ENDIAN())
		ctx->doByteReverse = 1;
	else
		ctx->doByteReverse = 0;
}



/**
 * md5_update: add a buffer to md5 hash computation
 * @ctx: context object used for md5 computaion
 * @buf: buffer to add
 * @len: buffer length
 *
 * Update context to reflect the concatenation of another buffer full
 * of bytes. Use this to progressively construct an md5 hash.
 **/
void
md5_update(MD5Context *ctx, const guchar *buf, guint32 len)
{
	guint32 t;

	/* Update bitcount */

	t = ctx->bits[0];
	if ((ctx->bits[0] = t + ((guint32) 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) {
		guchar *p = (guchar *) ctx->in + t;

		t = 64 - t;
		if (len < t) {
			memcpy(p, buf, len);
			return;
		}
		memcpy(p, buf, t);
		if (ctx->doByteReverse)
			_byte_reverse(ctx->in, 16);
		md5_transform(ctx->buf, (guint32 *) ctx->in);
		buf += t;
		len -= t;
	}
	/* Process data in 64-byte chunks */

	while (len >= 64) {
		memcpy(ctx->in, buf, 64);
		if (ctx->doByteReverse)
			_byte_reverse(ctx->in, 16);
		md5_transform(ctx->buf, (guint32 *) 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)
 */
/**
 * md5_final: copy the final md5 hash to a bufer
 * @digest: 16 bytes buffer
 * @ctx: context containing the calculated md5
 *
 * copy the final md5 hash to a bufer
 **/
void
md5_final(MD5Context *ctx, guchar digest[16])
{
	guint32 count;
	guchar *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);
		if (ctx->doByteReverse)
			_byte_reverse(ctx->in, 16);
		md5_transform(ctx->buf, (guint32 *) 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);
	}
	if (ctx->doByteReverse)
		_byte_reverse(ctx->in, 14);

	/* Append length in bits and transform */
	((guint32 *) ctx->in)[14] = ctx->bits[0];
	((guint32 *) ctx->in)[15] = ctx->bits[1];

	md5_transform(ctx->buf, (guint32 *) ctx->in);
	if (ctx->doByteReverse)
		_byte_reverse((guchar *) ctx->buf, 4);
	memcpy(digest, ctx->buf, 16);
}




/* 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.  md5_Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void
md5_transform(guint32 buf[4], const guint32 in[16])
{
	register guint32 a, b, c, d;

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

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

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

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

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

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




/**
 * md5_get_digest: get the md5 hash of a buffer
 * @buffer: byte buffer
 * @buffer_size: buffer size (in bytes)
 * @digest: 16 bytes buffer receiving the hash code.
 *
 * Get the md5 hash of a buffer. The result is put in
 * the 16 bytes buffer @digest .
 **/
void
md5_get_digest(const guchar *buffer, gint buffer_size, guchar digest[16])
{
	MD5Context ctx;

	md5_init(&ctx);
	md5_update(&ctx, buffer, buffer_size);
	md5_final(&ctx, digest);

}

/* modified for GQView, starting here */

/**
 * md5_get_digest_from_file: get the md5 hash of a file
 * @filename: file name
 * @digest: 16 bytes buffer receiving the hash code.
 * @return: TRUE on success
 *
 * Get the md5 hash of a file. The result is put in
 * the 16 bytes buffer @digest .
 **/
gboolean md5_get_digest_from_file(const gchar *path, guchar digest[16])
{
	MD5Context ctx;
	guchar tmp_buf[1024];
	gint nb_bytes_read;
	FILE *fp;
	gint success;

	fp = fopen(path, "r");
	if (!fp) return FALSE;

	md5_init(&ctx);

	while ((nb_bytes_read = fread(tmp_buf, sizeof (guchar), sizeof(tmp_buf), fp)) > 0)
		{
		md5_update(&ctx, tmp_buf, nb_bytes_read);
		}

	success = (ferror(fp) == 0);
	fclose(fp);
	if (!success) return FALSE;

	md5_final(&ctx, digest);
	return TRUE;
}

/* these to and from text string converters were borrowed from
 * the libgnomeui library, where they are name thumb_digest_to/from_ascii
 *
 * this version of the from text util does buffer length checking,
 * and assumes a NULL terminated string.
 */

gchar *md5_digest_to_text(guchar digest[16])
{
	static gchar hex_digits[] = "0123456789abcdef";
	gchar *result;
	gint i;

	result = g_malloc(33);
	for (i = 0; i < 16; i++)
		{
		result[2*i] = hex_digits[digest[i] >> 4];
		result[2*i+1] = hex_digits[digest[i] & 0xf];
		}
	result[32] = '\0';

	return result;
}

gboolean md5_digest_from_text(const gchar *text, guchar digest[16])
{
	gint i;

	for (i = 0; i < 16; i++)
		{
		if (text[2*i] == '\0' || text[2*i+1] == '\0') return FALSE;
		digest[i] = g_ascii_xdigit_value(text[2*i]) << 4 |
			    g_ascii_xdigit_value(text[2*i + 1]);
	}

	return TRUE;
}

/* vim: set shiftwidth=8 softtabstop=0 cindent cinoptions={1s: */
