/*
 *  md5.c
 *
 *  Implements  the  MD5 Message-Digest Algorithm 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.  I  do  not  expect  this  file  to be used for
 *  general  purpose  MD5'ing  of large amounts of data, only for
 *  generating hashed passwords from limited input.
 *
 *  Sverre H. Huseby <sverrehu@online.no>
 */


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "postgres.h"
#include "libpq/crypt.h"

/*
 *	PRIVATE FUNCTIONS
 */

typedef unsigned char unsigned8;
typedef unsigned int  unsigned32;
typedef unsigned long unsigned64;

#ifdef FRONTEND
#undef palloc
#define palloc malloc
#undef pfree
#define pfree free
#endif

/*
 *	The returned array is allocated using malloc.  the caller should free it
 * 	when it is no longer needed.
 */
static unsigned8 *
createPaddedCopyWithLength(unsigned8 *b, unsigned32 *l)
{
	unsigned8  *ret;
	unsigned32 q;
	unsigned32 len, newLen448;
	unsigned64 len64;

	len = ((b == NULL) ? 0 : *l);
	newLen448 = len + 64 - (len % 64) - 8;
	if (newLen448 <= len)
		newLen448 += 64;

	*l = newLen448 + 8;
	if ((ret = (unsigned8 *) malloc(sizeof(unsigned8) * *l)) == NULL)
		return NULL;

	if (b != NULL)
		memcpy(ret, b, sizeof(unsigned8) * len);

	/* pad */
	ret[len] = 0x80;
	for (q = len + 1; q < newLen448; q++)
		ret[q] = 0x00;

	/* append length as a 64 bit bitcount */
	len64 = len;
	len64 <<= 3;
	q = newLen448;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q++] = (len64 & 0xFF);
	len64 >>= 8;
	ret[q] = (len64 & 0xFF);

	return ret;
}

#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 ROT_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

static void
doTheRounds(unsigned32 X[16], unsigned32 state[4])
{
	unsigned32 a, b, c, d;

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

	/* round 1 */
	a = b + ROT_LEFT((a + F(b, c, d) + X[ 0] + 0xd76aa478),  7);  /*  1 */
	d = a + ROT_LEFT((d + F(a, b, c) + X[ 1] + 0xe8c7b756), 12);  /*  2 */
	c = d + ROT_LEFT((c + F(d, a, b) + X[ 2] + 0x242070db), 17);  /*  3 */
	b = c + ROT_LEFT((b + F(c, d, a) + X[ 3] + 0xc1bdceee), 22);  /*  4 */
	a = b + ROT_LEFT((a + F(b, c, d) + X[ 4] + 0xf57c0faf),  7);  /*  5 */
	d = a + ROT_LEFT((d + F(a, b, c) + X[ 5] + 0x4787c62a), 12);  /*  6 */
	c = d + ROT_LEFT((c + F(d, a, b) + X[ 6] + 0xa8304613), 17);  /*  7 */
	b = c + ROT_LEFT((b + F(c, d, a) + X[ 7] + 0xfd469501), 22);  /*  8 */
	a = b + ROT_LEFT((a + F(b, c, d) + X[ 8] + 0x698098d8),  7);  /*  9 */
	d = a + ROT_LEFT((d + F(a, b, c) + X[ 9] + 0x8b44f7af), 12);  /* 10 */
	c = d + ROT_LEFT((c + F(d, a, b) + X[10] + 0xffff5bb1), 17);  /* 11 */
	b = c + ROT_LEFT((b + F(c, d, a) + X[11] + 0x895cd7be), 22);  /* 12 */
	a = b + ROT_LEFT((a + F(b, c, d) + X[12] + 0x6b901122),  7);  /* 13 */
	d = a + ROT_LEFT((d + F(a, b, c) + X[13] + 0xfd987193), 12);  /* 14 */
	c = d + ROT_LEFT((c + F(d, a, b) + X[14] + 0xa679438e), 17);  /* 15 */
	b = c + ROT_LEFT((b + F(c, d, a) + X[15] + 0x49b40821), 22);  /* 16 */

	/* round 2 */
	a = b + ROT_LEFT((a + G(b, c, d) + X[ 1] + 0xf61e2562),  5);  /* 17 */
	d = a + ROT_LEFT((d + G(a, b, c) + X[ 6] + 0xc040b340),  9);  /* 18 */
	c = d + ROT_LEFT((c + G(d, a, b) + X[11] + 0x265e5a51), 14);  /* 19 */
	b = c + ROT_LEFT((b + G(c, d, a) + X[ 0] + 0xe9b6c7aa), 20);  /* 20 */
	a = b + ROT_LEFT((a + G(b, c, d) + X[ 5] + 0xd62f105d),  5);  /* 21 */
	d = a + ROT_LEFT((d + G(a, b, c) + X[10] + 0x02441453),  9);  /* 22 */
	c = d + ROT_LEFT((c + G(d, a, b) + X[15] + 0xd8a1e681), 14);  /* 23 */
	b = c + ROT_LEFT((b + G(c, d, a) + X[ 4] + 0xe7d3fbc8), 20);  /* 24 */
	a = b + ROT_LEFT((a + G(b, c, d) + X[ 9] + 0x21e1cde6),  5);  /* 25 */
	d = a + ROT_LEFT((d + G(a, b, c) + X[14] + 0xc33707d6),  9);  /* 26 */
	c = d + ROT_LEFT((c + G(d, a, b) + X[ 3] + 0xf4d50d87), 14);  /* 27 */
	b = c + ROT_LEFT((b + G(c, d, a) + X[ 8] + 0x455a14ed), 20);  /* 28 */
	a = b + ROT_LEFT((a + G(b, c, d) + X[13] + 0xa9e3e905),  5);  /* 29 */
	d = a + ROT_LEFT((d + G(a, b, c) + X[ 2] + 0xfcefa3f8),  9);  /* 30 */
	c = d + ROT_LEFT((c + G(d, a, b) + X[ 7] + 0x676f02d9), 14);  /* 31 */
	b = c + ROT_LEFT((b + G(c, d, a) + X[12] + 0x8d2a4c8a), 20);  /* 32 */

	/* round 3 */
	a = b + ROT_LEFT((a + H(b, c, d) + X[ 5] + 0xfffa3942),  4);  /* 33 */
	d = a + ROT_LEFT((d + H(a, b, c) + X[ 8] + 0x8771f681), 11);  /* 34 */
	c = d + ROT_LEFT((c + H(d, a, b) + X[11] + 0x6d9d6122), 16);  /* 35 */
	b = c + ROT_LEFT((b + H(c, d, a) + X[14] + 0xfde5380c), 23);  /* 36 */
	a = b + ROT_LEFT((a + H(b, c, d) + X[ 1] + 0xa4beea44),  4);  /* 37 */
	d = a + ROT_LEFT((d + H(a, b, c) + X[ 4] + 0x4bdecfa9), 11);  /* 38 */
	c = d + ROT_LEFT((c + H(d, a, b) + X[ 7] + 0xf6bb4b60), 16);  /* 39 */
	b = c + ROT_LEFT((b + H(c, d, a) + X[10] + 0xbebfbc70), 23);  /* 40 */
	a = b + ROT_LEFT((a + H(b, c, d) + X[13] + 0x289b7ec6),  4);  /* 41 */
	d = a + ROT_LEFT((d + H(a, b, c) + X[ 0] + 0xeaa127fa), 11);  /* 42 */
	c = d + ROT_LEFT((c + H(d, a, b) + X[ 3] + 0xd4ef3085), 16);  /* 43 */
	b = c + ROT_LEFT((b + H(c, d, a) + X[ 6] + 0x04881d05), 23);  /* 44 */
	a = b + ROT_LEFT((a + H(b, c, d) + X[ 9] + 0xd9d4d039),  4);  /* 45 */
	d = a + ROT_LEFT((d + H(a, b, c) + X[12] + 0xe6db99e5), 11);  /* 46 */
	c = d + ROT_LEFT((c + H(d, a, b) + X[15] + 0x1fa27cf8), 16);  /* 47 */
	b = c + ROT_LEFT((b + H(c, d, a) + X[ 2] + 0xc4ac5665), 23);  /* 48 */

	/* round 4 */
	a = b + ROT_LEFT((a + I(b, c, d) + X[ 0] + 0xf4292244),  6);  /* 49 */
	d = a + ROT_LEFT((d + I(a, b, c) + X[ 7] + 0x432aff97), 10);  /* 50 */
	c = d + ROT_LEFT((c + I(d, a, b) + X[14] + 0xab9423a7), 15);  /* 51 */
	b = c + ROT_LEFT((b + I(c, d, a) + X[ 5] + 0xfc93a039), 21);  /* 52 */
	a = b + ROT_LEFT((a + I(b, c, d) + X[12] + 0x655b59c3),  6);  /* 53 */
	d = a + ROT_LEFT((d + I(a, b, c) + X[ 3] + 0x8f0ccc92), 10);  /* 54 */
	c = d + ROT_LEFT((c + I(d, a, b) + X[10] + 0xffeff47d), 15);  /* 55 */
	b = c + ROT_LEFT((b + I(c, d, a) + X[ 1] + 0x85845dd1), 21);  /* 56 */
	a = b + ROT_LEFT((a + I(b, c, d) + X[ 8] + 0x6fa87e4f),  6);  /* 57 */
	d = a + ROT_LEFT((d + I(a, b, c) + X[15] + 0xfe2ce6e0), 10);  /* 58 */
	c = d + ROT_LEFT((c + I(d, a, b) + X[ 6] + 0xa3014314), 15);  /* 59 */
	b = c + ROT_LEFT((b + I(c, d, a) + X[13] + 0x4e0811a1), 21);  /* 60 */
	a = b + ROT_LEFT((a + I(b, c, d) + X[ 4] + 0xf7537e82),  6);  /* 61 */
	d = a + ROT_LEFT((d + I(a, b, c) + X[11] + 0xbd3af235), 10);  /* 62 */
	c = d + ROT_LEFT((c + I(d, a, b) + X[ 2] + 0x2ad7d2bb), 15);  /* 63 */
	b = c + ROT_LEFT((b + I(c, d, a) + X[ 9] + 0xeb86d391), 21);  /* 64 */

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

static int
calculateDigestFromBuffer(unsigned8 *b, unsigned32 len, unsigned8 sum[16])
{
	register unsigned32 i, j, k, newI;
	unsigned32 l;
	unsigned8 *input;
	register unsigned32 *wbp;
	unsigned32 workBuff[16], state[4];

	l = len;

	state[0] = 0x67452301;
	state[1] = 0xEFCDAB89;
	state[2] = 0x98BADCFE;
	state[3] = 0x10325476;

	if ((input = createPaddedCopyWithLength(b, &l)) == NULL)
		return 0;

	for (i = 0;;) {
		if ((newI = i + 16 * 4) > l)
			break;
		k = i + 3;
		for (j = 0; j < 16; j++) {
			wbp = (workBuff + j);
			*wbp = input[k--];
			*wbp <<= 8;
			*wbp |= input[k--];
			*wbp <<= 8;
			*wbp |= input[k--];
			*wbp <<= 8;
			*wbp |= input[k];
			k += 7;
		}
		doTheRounds(workBuff, state);
		i = newI;
	}
	free(input);

	j = 0;
	for (i = 0; i < 4; i++) {
		k = state[i];
		sum[j++] = (k & 0xFF);
		k >>= 8;
		sum[j++] = (k & 0xFF);
		k >>= 8;
		sum[j++] = (k & 0xFF);
		k >>= 8;
		sum[j++] = (k & 0xFF);
	}
	return 1;
}

static void
bytesToHex(unsigned8 b[16], char *s)
{
	static char *hex = "0123456789abcdef";
	int         q, w;

	for (q = 0, w = 0; q < 16; q++) {
		s[w++] = hex[(b[q] >> 4) & 0x0F];
		s[w++] = hex[b[q] & 0x0F];
	}
	s[w] = '\0';
}

/*
 *  PUBLIC FUNCTIONS
 */

/*
 *  md5_hash
 *
 *  Calculates the MD5 sum of the bytes in a buffer.
 *
 *  SYNOPSIS      #include "crypt.h"
 *                int md5_hash(const void *buff, size_t len, char *hexsum)
 *
 *  INPUT         buff    the buffer containing the bytes that you want
 *                        the MD5 sum of.
 *                len     number of bytes in the buffer.
 *
 *  OUTPUT        hexsum  the MD5 sum as a '\0'-terminated string of
 *                        hexadecimal digits.  an MD5 sum is 16 bytes long.
 *                        each byte is represented by two heaxadecimal
 *                        characters.  you thus need to provide an array
 *                        of 33 characters, including the trailing '\0'.
 *
 *  RETURNS       0 on failure (out of memory for internal buffers) or
 *                non-zero on success.
 *
 *  STANDARDS     MD5 is described in RFC 1321.
 *
 *  AUTHOR        Sverre H. Huseby <sverrehu@online.no>
 *
 */
bool
md5_hash(const void *buff, size_t len, char *hexsum)
{
	unsigned8 sum[16];

	if (!calculateDigestFromBuffer((unsigned8 *) buff, len, sum))
		return false;

	bytesToHex(sum, hexsum);
	return true;
}



/*
 * puts  md5(username+passwd)  in buf provided buflen is at least 36 bytes
 * returns 1 on success, 0 on any kind of failure and sets errno accordingly
 */
bool EncryptMD5(const char *passwd, const char *salt, size_t salt_len,
				char *buf)
{
	char crypt_buf[128];

	if (salt_len + strlen(passwd) > 127)
		return false;

	strcpy(buf, "md5");
	memset(crypt_buf, 0, 128);
	memcpy(crypt_buf, salt, salt_len);
	memcpy(crypt_buf+salt_len, passwd, strlen(passwd));

	return md5_hash(crypt_buf, salt_len + strlen(passwd), buf + 3);
}
