/*-------------------------------------------------------------------------
 *
 *	md5.c
 *	  Implements the MD5 Message-Digest Algorithm
 *
 * Fallback implementation of MD5, as specified in RFC 1321.  This
 * implementation is a simple one, in that it needs every input byte
 * to be buffered before doing any calculations.
 *
 *	Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 *	Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *	  src/common/md5.c
 *
 *-------------------------------------------------------------------------
 */

/*    $KAME: md5.c,v 1.3 2000/02/22 14:01:17 itojun Exp $     */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#include "md5_int.h"

#define SHIFT(X, s) (((X) << (s)) | ((X) >> (32 - (s))))

#define F(X, Y, Z) (((X) & (Y)) | ((~X) & (Z)))
#define G(X, Y, Z) (((X) & (Z)) | ((Y) & (~Z)))
#define H(X, Y, Z) ((X) ^ (Y) ^ (Z))
#define I(X, Y, Z) ((Y) ^ ((X) | (~Z)))

#define ROUND1(a, b, c, d, k, s, i) \
do { \
	(a) = (a) + F((b), (c), (d)) + X[(k)] + T[(i)]; \
	(a) = SHIFT((a), (s)); \
	(a) = (b) + (a); \
} while (0)

#define ROUND2(a, b, c, d, k, s, i) \
do { \
	(a) = (a) + G((b), (c), (d)) + X[(k)] + T[(i)]; \
	(a) = SHIFT((a), (s)); \
	(a) = (b) + (a); \
} while (0)

#define ROUND3(a, b, c, d, k, s, i) \
do { \
	(a) = (a) + H((b), (c), (d)) + X[(k)] + T[(i)]; \
	(a) = SHIFT((a), (s)); \
	(a) = (b) + (a); \
} while (0)

#define ROUND4(a, b, c, d, k, s, i) \
do { \
	(a) = (a) + I((b), (c), (d)) + X[(k)] + T[(i)]; \
	(a) = SHIFT((a), (s)); \
	(a) = (b) + (a); \
} while (0)

#define Sa	 7
#define Sb	12
#define Sc	17
#define Sd	22

#define Se	 5
#define Sf	 9
#define Sg	14
#define Sh	20

#define Si	 4
#define Sj	11
#define Sk	16
#define Sl	23

#define Sm	 6
#define Sn	10
#define So	15
#define Sp	21

#define MD5_A0	0x67452301
#define MD5_B0	0xefcdab89
#define MD5_C0	0x98badcfe
#define MD5_D0	0x10325476

/* Integer part of 4294967296 times abs(sin(i)), where i is in radians. */
static const uint32 T[65] = {
	0,
	0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
	0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
	0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
	0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,

	0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
	0xd62f105d, 0x2441453, 0xd8a1e681, 0xe7d3fbc8,
	0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
	0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,

	0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
	0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
	0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x4881d05,
	0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,

	0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
	0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
	0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
	0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391,
};

static const uint8 md5_paddat[MD5_BUFLEN] = {
	0x80, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0,
};

#ifdef WORDS_BIGENDIAN
static uint32 X[16];
#endif

static void
md5_calc(const uint8 *b64, pg_md5_ctx *ctx)
{
	uint32		A = ctx->md5_sta;
	uint32		B = ctx->md5_stb;
	uint32		C = ctx->md5_stc;
	uint32		D = ctx->md5_std;

#ifndef WORDS_BIGENDIAN
	const uint32 *X = (const uint32 *) b64;
#else
	/* 4 byte words */
	/* what a brute force but fast! */
	uint8	   *y = (uint8 *) X;

	y[0] = b64[3];
	y[1] = b64[2];
	y[2] = b64[1];
	y[3] = b64[0];
	y[4] = b64[7];
	y[5] = b64[6];
	y[6] = b64[5];
	y[7] = b64[4];
	y[8] = b64[11];
	y[9] = b64[10];
	y[10] = b64[9];
	y[11] = b64[8];
	y[12] = b64[15];
	y[13] = b64[14];
	y[14] = b64[13];
	y[15] = b64[12];
	y[16] = b64[19];
	y[17] = b64[18];
	y[18] = b64[17];
	y[19] = b64[16];
	y[20] = b64[23];
	y[21] = b64[22];
	y[22] = b64[21];
	y[23] = b64[20];
	y[24] = b64[27];
	y[25] = b64[26];
	y[26] = b64[25];
	y[27] = b64[24];
	y[28] = b64[31];
	y[29] = b64[30];
	y[30] = b64[29];
	y[31] = b64[28];
	y[32] = b64[35];
	y[33] = b64[34];
	y[34] = b64[33];
	y[35] = b64[32];
	y[36] = b64[39];
	y[37] = b64[38];
	y[38] = b64[37];
	y[39] = b64[36];
	y[40] = b64[43];
	y[41] = b64[42];
	y[42] = b64[41];
	y[43] = b64[40];
	y[44] = b64[47];
	y[45] = b64[46];
	y[46] = b64[45];
	y[47] = b64[44];
	y[48] = b64[51];
	y[49] = b64[50];
	y[50] = b64[49];
	y[51] = b64[48];
	y[52] = b64[55];
	y[53] = b64[54];
	y[54] = b64[53];
	y[55] = b64[52];
	y[56] = b64[59];
	y[57] = b64[58];
	y[58] = b64[57];
	y[59] = b64[56];
	y[60] = b64[63];
	y[61] = b64[62];
	y[62] = b64[61];
	y[63] = b64[60];
#endif

	ROUND1(A, B, C, D, 0, Sa, 1);
	ROUND1(D, A, B, C, 1, Sb, 2);
	ROUND1(C, D, A, B, 2, Sc, 3);
	ROUND1(B, C, D, A, 3, Sd, 4);
	ROUND1(A, B, C, D, 4, Sa, 5);
	ROUND1(D, A, B, C, 5, Sb, 6);
	ROUND1(C, D, A, B, 6, Sc, 7);
	ROUND1(B, C, D, A, 7, Sd, 8);
	ROUND1(A, B, C, D, 8, Sa, 9);
	ROUND1(D, A, B, C, 9, Sb, 10);
	ROUND1(C, D, A, B, 10, Sc, 11);
	ROUND1(B, C, D, A, 11, Sd, 12);
	ROUND1(A, B, C, D, 12, Sa, 13);
	ROUND1(D, A, B, C, 13, Sb, 14);
	ROUND1(C, D, A, B, 14, Sc, 15);
	ROUND1(B, C, D, A, 15, Sd, 16);

	ROUND2(A, B, C, D, 1, Se, 17);
	ROUND2(D, A, B, C, 6, Sf, 18);
	ROUND2(C, D, A, B, 11, Sg, 19);
	ROUND2(B, C, D, A, 0, Sh, 20);
	ROUND2(A, B, C, D, 5, Se, 21);
	ROUND2(D, A, B, C, 10, Sf, 22);
	ROUND2(C, D, A, B, 15, Sg, 23);
	ROUND2(B, C, D, A, 4, Sh, 24);
	ROUND2(A, B, C, D, 9, Se, 25);
	ROUND2(D, A, B, C, 14, Sf, 26);
	ROUND2(C, D, A, B, 3, Sg, 27);
	ROUND2(B, C, D, A, 8, Sh, 28);
	ROUND2(A, B, C, D, 13, Se, 29);
	ROUND2(D, A, B, C, 2, Sf, 30);
	ROUND2(C, D, A, B, 7, Sg, 31);
	ROUND2(B, C, D, A, 12, Sh, 32);

	ROUND3(A, B, C, D, 5, Si, 33);
	ROUND3(D, A, B, C, 8, Sj, 34);
	ROUND3(C, D, A, B, 11, Sk, 35);
	ROUND3(B, C, D, A, 14, Sl, 36);
	ROUND3(A, B, C, D, 1, Si, 37);
	ROUND3(D, A, B, C, 4, Sj, 38);
	ROUND3(C, D, A, B, 7, Sk, 39);
	ROUND3(B, C, D, A, 10, Sl, 40);
	ROUND3(A, B, C, D, 13, Si, 41);
	ROUND3(D, A, B, C, 0, Sj, 42);
	ROUND3(C, D, A, B, 3, Sk, 43);
	ROUND3(B, C, D, A, 6, Sl, 44);
	ROUND3(A, B, C, D, 9, Si, 45);
	ROUND3(D, A, B, C, 12, Sj, 46);
	ROUND3(C, D, A, B, 15, Sk, 47);
	ROUND3(B, C, D, A, 2, Sl, 48);

	ROUND4(A, B, C, D, 0, Sm, 49);
	ROUND4(D, A, B, C, 7, Sn, 50);
	ROUND4(C, D, A, B, 14, So, 51);
	ROUND4(B, C, D, A, 5, Sp, 52);
	ROUND4(A, B, C, D, 12, Sm, 53);
	ROUND4(D, A, B, C, 3, Sn, 54);
	ROUND4(C, D, A, B, 10, So, 55);
	ROUND4(B, C, D, A, 1, Sp, 56);
	ROUND4(A, B, C, D, 8, Sm, 57);
	ROUND4(D, A, B, C, 15, Sn, 58);
	ROUND4(C, D, A, B, 6, So, 59);
	ROUND4(B, C, D, A, 13, Sp, 60);
	ROUND4(A, B, C, D, 4, Sm, 61);
	ROUND4(D, A, B, C, 11, Sn, 62);
	ROUND4(C, D, A, B, 2, So, 63);
	ROUND4(B, C, D, A, 9, Sp, 64);

	ctx->md5_sta += A;
	ctx->md5_stb += B;
	ctx->md5_stc += C;
	ctx->md5_std += D;
}

static void
md5_pad(pg_md5_ctx *ctx)
{
	unsigned int gap;

	/* Don't count up padding. Keep md5_n. */
	gap = MD5_BUFLEN - ctx->md5_i;
	if (gap > 8)
	{
		memmove(ctx->md5_buf + ctx->md5_i, md5_paddat,
				gap - sizeof(ctx->md5_n));
	}
	else
	{
		/* including gap == 8 */
		memmove(ctx->md5_buf + ctx->md5_i, md5_paddat, gap);
		md5_calc(ctx->md5_buf, ctx);
		memmove(ctx->md5_buf, md5_paddat + gap,
				MD5_BUFLEN - sizeof(ctx->md5_n));
	}

	/* 8 byte word */
#ifndef WORDS_BIGENDIAN
	memmove(&ctx->md5_buf[56], &ctx->md5_n8[0], 8);
#else
	ctx->md5_buf[56] = ctx->md5_n8[7];
	ctx->md5_buf[57] = ctx->md5_n8[6];
	ctx->md5_buf[58] = ctx->md5_n8[5];
	ctx->md5_buf[59] = ctx->md5_n8[4];
	ctx->md5_buf[60] = ctx->md5_n8[3];
	ctx->md5_buf[61] = ctx->md5_n8[2];
	ctx->md5_buf[62] = ctx->md5_n8[1];
	ctx->md5_buf[63] = ctx->md5_n8[0];
#endif

	md5_calc(ctx->md5_buf, ctx);
}

static void
md5_result(uint8 *digest, pg_md5_ctx *ctx)
{
	/* 4 byte words */
#ifndef WORDS_BIGENDIAN
	memmove(digest, &ctx->md5_st8[0], 16);
#else
	digest[0] = ctx->md5_st8[3];
	digest[1] = ctx->md5_st8[2];
	digest[2] = ctx->md5_st8[1];
	digest[3] = ctx->md5_st8[0];
	digest[4] = ctx->md5_st8[7];
	digest[5] = ctx->md5_st8[6];
	digest[6] = ctx->md5_st8[5];
	digest[7] = ctx->md5_st8[4];
	digest[8] = ctx->md5_st8[11];
	digest[9] = ctx->md5_st8[10];
	digest[10] = ctx->md5_st8[9];
	digest[11] = ctx->md5_st8[8];
	digest[12] = ctx->md5_st8[15];
	digest[13] = ctx->md5_st8[14];
	digest[14] = ctx->md5_st8[13];
	digest[15] = ctx->md5_st8[12];
#endif
}


/* External routines for this MD5 implementation */

/*
 * pg_md5_init
 *
 * Initialize a MD5 context.
 */
void
pg_md5_init(pg_md5_ctx *ctx)
{
	ctx->md5_n = 0;
	ctx->md5_i = 0;
	ctx->md5_sta = MD5_A0;
	ctx->md5_stb = MD5_B0;
	ctx->md5_stc = MD5_C0;
	ctx->md5_std = MD5_D0;
	memset(ctx->md5_buf, 0, sizeof(ctx->md5_buf));
}


/*
 * pg_md5_update
 *
 * Update a MD5 context.
 */
void
pg_md5_update(pg_md5_ctx *ctx, const uint8 *data, size_t len)
{
	unsigned int gap,
				i;

	ctx->md5_n += len * 8;		/* byte to bit */
	gap = MD5_BUFLEN - ctx->md5_i;

	if (len >= gap)
	{
		memmove(ctx->md5_buf + ctx->md5_i, data, gap);
		md5_calc(ctx->md5_buf, ctx);

		for (i = gap; i + MD5_BUFLEN <= len; i += MD5_BUFLEN)
			md5_calc(data + i, ctx);

		ctx->md5_i = len - i;
		memmove(ctx->md5_buf, data + i, ctx->md5_i);
	}
	else
	{
		memmove(ctx->md5_buf + ctx->md5_i, data, len);
		ctx->md5_i += len;
	}
}

/*
 * pg_md5_final
 *
 * Finalize a MD5 context.
 */
void
pg_md5_final(pg_md5_ctx *ctx, uint8 *dest)
{
	md5_pad(ctx);
	md5_result(dest, ctx);
}