// SPDX-License-Identifier: BSD-3-Clause
/*
 * Copyright (C) 2004 6WIND
 *                          <Vincent.Jardin@6WIND.com>
 * All rights reserved.
 *
 * This MD5 code is Big endian and Little Endian compatible.
 */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 */

#include <zebra.h>
#include "md5.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)                                            \
	{                                                                      \
		(a) = (a) + F((b), (c), (d)) + X[(k)] + T[(i)];                \
		(a) = SHIFT((a), (s));                                         \
		(a) = (b) + (a);                                               \
	}

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

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

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

#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 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_t 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,
};

static void md5_calc(const uint8_t *, md5_ctxt *);

void md5_init(md5_ctxt *ctxt)
{
	ctxt->md5_n = 0;
	ctxt->md5_i = 0;
	ctxt->md5_sta = MD5_A0;
	ctxt->md5_stb = MD5_B0;
	ctxt->md5_stc = MD5_C0;
	ctxt->md5_std = MD5_D0;
	memset(ctxt->md5_buf, 0, sizeof(ctxt->md5_buf));
}

void md5_loop(md5_ctxt *ctxt, const void *vinput, uint len)
{
	uint gap, i;
	const uint8_t *input = vinput;

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

	if (len >= gap) {
		memcpy(ctxt->md5_buf + ctxt->md5_i, input, gap);
		md5_calc(ctxt->md5_buf, ctxt);

		for (i = gap; i + MD5_BUFLEN <= len; i += MD5_BUFLEN) {
			md5_calc((input + i), ctxt);
		}

		ctxt->md5_i = len - i;
		memcpy(ctxt->md5_buf, (input + i), ctxt->md5_i);
	} else {
		memcpy(ctxt->md5_buf + ctxt->md5_i, input, len);
		ctxt->md5_i += len;
	}
}

void md5_pad(md5_ctxt *ctxt)
{
	uint gap;

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

	/* 8 byte word */
	if (BYTE_ORDER == LITTLE_ENDIAN)
		memcpy(&ctxt->md5_buf[56], &ctxt->md5_n8[0], 8);
	else {
		ctxt->md5_buf[56] = ctxt->md5_n8[7];
		ctxt->md5_buf[57] = ctxt->md5_n8[6];
		ctxt->md5_buf[58] = ctxt->md5_n8[5];
		ctxt->md5_buf[59] = ctxt->md5_n8[4];
		ctxt->md5_buf[60] = ctxt->md5_n8[3];
		ctxt->md5_buf[61] = ctxt->md5_n8[2];
		ctxt->md5_buf[62] = ctxt->md5_n8[1];
		ctxt->md5_buf[63] = ctxt->md5_n8[0];
	}
	md5_calc(ctxt->md5_buf, ctxt);
}

void md5_result(uint8_t *digest, md5_ctxt *ctxt)
{
	/* 4 byte words */
	if (BYTE_ORDER == LITTLE_ENDIAN)
		memcpy(digest, &ctxt->md5_st8[0], 16);
	else if (BYTE_ORDER == BIG_ENDIAN) {
		digest[0] = ctxt->md5_st8[3];
		digest[1] = ctxt->md5_st8[2];
		digest[2] = ctxt->md5_st8[1];
		digest[3] = ctxt->md5_st8[0];
		digest[4] = ctxt->md5_st8[7];
		digest[5] = ctxt->md5_st8[6];
		digest[6] = ctxt->md5_st8[5];
		digest[7] = ctxt->md5_st8[4];
		digest[8] = ctxt->md5_st8[11];
		digest[9] = ctxt->md5_st8[10];
		digest[10] = ctxt->md5_st8[9];
		digest[11] = ctxt->md5_st8[8];
		digest[12] = ctxt->md5_st8[15];
		digest[13] = ctxt->md5_st8[14];
		digest[14] = ctxt->md5_st8[13];
		digest[15] = ctxt->md5_st8[12];
	}
}

static void md5_calc(const uint8_t *b64, md5_ctxt *ctxt)
{
	uint32_t A = ctxt->md5_sta;
	uint32_t B = ctxt->md5_stb;
	uint32_t C = ctxt->md5_stc;
	uint32_t D = ctxt->md5_std;
#if (BYTE_ORDER == LITTLE_ENDIAN)
	const uint32_t *X = (const uint32_t *)b64;
#elif (BYTE_ORDER == BIG_ENDIAN)
	uint32_t X[16];

	if (BYTE_ORDER == BIG_ENDIAN) {
		/* 4 byte words */
		/* what a brute force but fast! */
		uint8_t *y = (uint8_t *)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);

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

/* From RFC 2104 */
void hmac_md5(unsigned char *text, int text_len, unsigned char *key,
	      int key_len, uint8_t *digest)
{
	MD5_CTX context;
	unsigned char k_ipad[65]; /* inner padding -
				  * key XORd with ipad
				  */
	unsigned char k_opad[65]; /* outer padding -
				  * key XORd with opad
				  */
	unsigned char tk[16];
	int i;
	/* if key is longer than 64 bytes reset it to key=MD5(key) */
	if (key_len > 64) {

		MD5_CTX tctx;

		MD5Init(&tctx);
		MD5Update(&tctx, key, key_len);
		MD5Final(tk, &tctx);

		key = tk;
		key_len = 16;
	}

	/*
	 * the HMAC_MD5 transform looks like:
	 *
	 * MD5(K XOR opad, MD5(K XOR ipad, text))
	 *
	 * where K is an n byte key
	 * ipad is the byte 0x36 repeated 64 times
	 * opad is the byte 0x5c repeated 64 times
	 * and text is the data being protected
	 */

	/* start out by storing key in pads */
	bzero(k_ipad, sizeof(k_ipad));
	bzero(k_opad, sizeof(k_opad));
	bcopy(key, k_ipad, key_len);
	bcopy(key, k_opad, key_len);

	/* XOR key with ipad and opad values */
	for (i = 0; i < 64; i++) {
		k_ipad[i] ^= 0x36;
		k_opad[i] ^= 0x5c;
	}
	/*
	 * perform inner MD5
	 */
	MD5Init(&context);		       /* init context for 1st
						* pass */
	MD5Update(&context, k_ipad, 64);       /* start with inner pad */
	MD5Update(&context, text, text_len);   /* then text of datagram */
	MD5Final(digest, &context); /* finish up 1st pass */
	/*
	 * perform outer MD5
	 */
	MD5Init(&context);		       /* init context for 2nd
						* pass */
	MD5Update(&context, k_opad, 64);       /* start with outer pad */
	MD5Update(&context, digest, 16);       /* then results of 1st
						* hash */
	MD5Final(digest, &context); /* finish up 2nd pass */
	explicit_bzero(&context, sizeof(context));
}