/*
 *  zzuf - general purpose fuzzer
 *
 *  Copyright © 2002—2015 Sam Hocevar <sam@hocevar.net>
 *
 *  This program is free software. It comes without any warranty, to
 *  the extent permitted by applicable law. You can redistribute it
 *  and/or modify it under the terms of the Do What the Fuck You Want
 *  to Public License, Version 2, as published by the WTFPL Task Force.
 *  See http://www.wtfpl.net/ for more details.
 */

/*
 *  md5.c: MD5 computation. Written and put into the public domain
 *  by Colin Plumb in 1993.
 */

#include "config.h"

#if defined HAVE_STDINT_H
#   include <stdint.h>
#elif defined HAVE_INTTYPES_H
#   include <inttypes.h>
#endif
#if defined HAVE_ENDIAN_H
#   include <endian.h>
#endif
#include <string.h>
#include <stdlib.h>

#include "util/md5.h"

struct zzuf_md5sum
{
    uint32_t buf[4];
    uint32_t bits[2];
    uint32_t in[64];
};

static void swapwords(uint32_t *buf, unsigned words);
static void transform(uint32_t buf[4], uint32_t in[16]);

zzuf_md5sum_t *zzuf_create_md5(void)
{
    zzuf_md5sum_t *ctx = malloc(sizeof(zzuf_md5sum_t));

    ctx->buf[0] = 0x67452301;
    ctx->buf[1] = 0xefcdab89;
    ctx->buf[2] = 0x98badcfe;
    ctx->buf[3] = 0x10325476;

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

    return ctx;
}

void zz_md5_add(zzuf_md5sum_t *ctx, uint8_t *buf, unsigned len)
{
    uint32_t t = ctx->bits[0];
    if ((ctx->bits[0] = t + ((uint32_t)len << 3)) < t)
        ctx->bits[1]++;
    ctx->bits[1] += len >> 29;

    t = (t >> 3) & 0x3f;

    if (t)
    {
        uint8_t *p = (uint8_t *)ctx->in + t;

        t = 64 - t;
        if (len < t)
        {
            memcpy(p, buf, len);
            return;
        }
        memcpy(p, buf, t);
        swapwords(ctx->in, 64 / 4);
        transform(ctx->buf, ctx->in);
        buf += t;
        len -= t;
    }

    while (len >= 64)
    {
        memcpy(ctx->in, buf, 64);
        swapwords(ctx->in, 64 / 4);
        transform(ctx->buf, ctx->in);
        buf += 64;
        len -= 64;
    }

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

void zzuf_destroy_md5(uint8_t *digest, zzuf_md5sum_t *ctx)
{
    unsigned count = (ctx->bits[0] >> 3) & 0x3F;
    uint8_t *p = (uint8_t *)ctx->in + count;
    *p++ = 0x80;

    count = 64 - 1 - count;
    if (count < 8)
    {
        memset(p, 0, count);
        swapwords(ctx->in, 64 / 4);
        transform(ctx->buf, ctx->in);
        memset(ctx->in, 0, 56);
    }
    else
        memset(p, 0, count - 8);

    swapwords(ctx->in, 56 / 4);
    memcpy(ctx->in + 56 / 4, ctx->bits, 8);
    transform(ctx->buf, ctx->in);
    swapwords(ctx->buf, 16 / 4);
    memcpy(digest, ctx->buf, 16);
    free(ctx);
}

static void swapwords(uint32_t *buf, unsigned words)
{
    /* XXX: no need to swap words on little endian machines */
#if defined HAVE_ENDIAN_H
    if (__BYTE_ORDER == __LITTLE_ENDIAN)
        return;
#else
    /* This is compile-time optimised with at least -O1 or -Os */
    uint32_t const tmp = 0x12345678;
    if (*(uint8_t const *)&tmp == 0x78)
        return;
#endif

    while (words > 0)
    {
        uint8_t *b = (uint8_t *)buf;
        *buf++ = (uint32_t)b[3] << 24 | b[2] << 16 | b[1] << 8 | b[0];
        words--;
    }
}

/* #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))

#define MD5STEP(f, w, x, y, z, data, s) \
    (w += f(x, y, z) + data, w = w << s | w >> (32 - s), w += x)

static void transform(uint32_t buf[4], uint32_t in[16])
{
    uint32_t a = buf[0];
    uint32_t b = buf[1];
    uint32_t c = buf[2];
    uint32_t 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;
}