/*
  * 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 MD5Init, call MD5Update as
  * needed on buffers full of bytes, and then call MD5Final, which
  * will fill a supplied 16-byte array with the digest.
  *
  */
 
 #if HAVE_CONFIG_H
 #include "clamav-config.h"

 #endif
 

 #include <string.h>		/* for memcpy() */
 #include <sys/types.h>		/* for stupid systems */
 #include <netinet/in.h>		/* for ntohl() */

 
 #include "md5.h"
 

 #if WORDS_BIGENDIAN

 void

 byteSwap(uint32_t *buf, unsigned words)

 {

 	md5byte *p = (md5byte *)buf;

 	do {
 		*buf++ = (uint32_t)((unsigned)p[3] << 8 | p[2]) << 16 |
 			((unsigned)p[1] << 8 | p[0]);
 		p += 4;
 	} while (--words);

 }

 #else
 #define byteSwap(buf,words)
 #endif

 /*
  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
  * initialization constants.
  */
 void
 MD5Init(struct MD5Context *ctx)

 {

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

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

 }
 

 /*
  * Update context to reflect the concatenation of another buffer full
  * of bytes.
  */
 void
 MD5Update(struct MD5Context *ctx, md5byte const *buf, unsigned len)

 {

 	uint32_t t;

 	/* Update byte count */

 	t = ctx->bytes[0];
 	if ((ctx->bytes[0] = t + len) < t)
 		ctx->bytes[1]++;	/* Carry from low to high */

 	t = 64 - (t & 0x3f);	/* Space available in ctx->in (at least 1) */
 	if (t > len) {
 		memcpy((md5byte *)ctx->in + 64 - t, buf, len);
 		return;
 	}
 	/* First chunk is an odd size */
 	memcpy((md5byte *)ctx->in + 64 - t, buf, t);
 	byteSwap(ctx->in, 16);
 	MD5Transform(ctx->buf, ctx->in);
 	buf += t;
 	len -= t;
 
 	/* Process data in 64-byte chunks */
 	while (len >= 64) {
 		memcpy(ctx->in, buf, 64);
 		byteSwap(ctx->in, 16);
 		MD5Transform(ctx->buf, 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)
  */

 void

 MD5Final(md5byte *digest, struct MD5Context *ctx)

 {

 	int count = ctx->bytes[0] & 0x3f;	/* Number of bytes in ctx->in */
 	md5byte *p = (md5byte *)ctx->in + count;

 	/* Set the first char of padding to 0x80.  There is always room. */
 	*p++ = 0x80;

 	/* Bytes of padding needed to make 56 bytes (-8..55) */
 	count = 56 - 1 - count;

 	if (count < 0) {	/* Padding forces an extra block */
 		memset(p, 0, count + 8);
 		byteSwap(ctx->in, 16);
 		MD5Transform(ctx->buf, ctx->in);
 		p = (md5byte *)ctx->in;
 		count = 56;

 	}

 	memset(p, 0, count);
 	byteSwap(ctx->in, 14);

 	/* Append length in bits and transform */
 	ctx->in[14] = ctx->bytes[0] << 3;
 	ctx->in[15] = ctx->bytes[1] << 3 | ctx->bytes[0] >> 29;
 	MD5Transform(ctx->buf, ctx->in);

 	byteSwap(ctx->buf, 4);
 	memcpy(digest, ctx->buf, 16);
 	memset(ctx, 0, sizeof(ctx));	/* In case it's sensitive */

 }
 

 /* 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,in,s) \
 	 (w += f(x,y,z) + in, w = (w<<s | w>>(32-s)) + x)

 /*
  * The core of the MD5 algorithm, this alters an existing MD5 hash to
  * reflect the addition of 16 longwords of new data.  MD5Update blocks
  * the data and converts bytes into longwords for this routine.
  */

 void

 MD5Transform(uint32_t buf[4], uint32_t const in[16])

 {

 	uint32_t 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;

 }