#include <alef.h>
#include <bio.h>

/*
 *  rfc1321 requires that I include this.  The code is new.  The constants
 *  all some from the rfc (hence the copyright).  We trade a table for the
 *  macros in rfc.  The total size is a lot less. -- presotto
 *
 *	Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
 *	rights reserved.
 *
 *	License to copy and use this software is granted provided that it
 *	is identified as the "RSA Data Security, Inc. MD5 Message-Digest
 *	Algorithm" in all material mentioning or referencing this software
 *	or this function.
 *
 *	License is also granted to make and use derivative works provided
 *	that such works are identified as "derived from the RSA Data
 *	Security, Inc. MD5 Message-Digest Algorithm" in all material
 *	mentioning or referencing the derived work.
 *
 *	RSA Data Security, Inc. makes no representations concerning either
 *	the merchantability of this software or the suitability of this
 *	software forany particular purpose. It is provided "as is"
 *	without express or implied warranty of any kind.
 *	These notices must be retained in any copies of any part of this
 *	documentation and/or software.
 */

/*
 *	Rotate ammounts used in the algorithm
 */
enum
{
	S11=	7,
	S12=	12,
	S13=	17,
	S14=	22,

	S21=	5,
	S22=	9,
	S23=	14,
	S24=	20,

	S31=	4,
	S32=	11,
	S33=	16,
	S34=	23,

	S41=	6,
	S42=	10,
	S43=	15,
	S44=	21,
};

aggr Table
{
	uint	sin;	/* integer part of 4294967296 times abs(sin(i)) */
	byte	x;	/* index into data block */
	byte	rot;	/* amount to rotate left by */
};

intern Table tab[] =
{
	/* round 1 */
[0]	{ 0xd76aa478, 0, S11},	
	{ 0xe8c7b756, 1, S12},	
	{ 0x242070db, 2, S13},	
	{ 0xc1bdceee, 3, S14},	
	{ 0xf57c0faf, 4, S11},	
	{ 0x4787c62a, 5, S12},	
	{ 0xa8304613, 6, S13},	
	{ 0xfd469501, 7, S14},	
	{ 0x698098d8, 8, S11},	
	{ 0x8b44f7af, 9, S12},	
	{ 0xffff5bb1, 10, S13},	
	{ 0x895cd7be, 11, S14},	
	{ 0x6b901122, 12, S11},	
	{ 0xfd987193, 13, S12},	
	{ 0xa679438e, 14, S13},	
	{ 0x49b40821, 15, S14},

	/* round 2 */
[16]	{ 0xf61e2562, 1, S21},	
	{ 0xc040b340, 6, S22},	
	{ 0x265e5a51, 11, S23},	
	{ 0xe9b6c7aa, 0, S24},	
	{ 0xd62f105d, 5, S21},	
	{  0x2441453, 10, S22},	
	{ 0xd8a1e681, 15, S23},	
	{ 0xe7d3fbc8, 4, S24},	
	{ 0x21e1cde6, 9, S21},	
	{ 0xc33707d6, 14, S22},	
	{ 0xf4d50d87, 3, S23},	
	{ 0x455a14ed, 8, S24},	
	{ 0xa9e3e905, 13, S21},	
	{ 0xfcefa3f8, 2, S22},	
	{ 0x676f02d9, 7, S23},	
	{ 0x8d2a4c8a, 12, S24},

	/* round 3 */
[32]	{ 0xfffa3942, 5, S31},	
	{ 0x8771f681, 8, S32},	
	{ 0x6d9d6122, 11, S33},	
	{ 0xfde5380c, 14, S34},	
	{ 0xa4beea44, 1, S31},	
	{ 0x4bdecfa9, 4, S32},	
	{ 0xf6bb4b60, 7, S33},	
	{ 0xbebfbc70, 10, S34},	
	{ 0x289b7ec6, 13, S31},	
	{ 0xeaa127fa, 0, S32},	
	{ 0xd4ef3085, 3, S33},	
	{  0x4881d05, 6, S34},	
	{ 0xd9d4d039, 9, S31},	
	{ 0xe6db99e5, 12, S32},	
	{ 0x1fa27cf8, 15, S33},	
	{ 0xc4ac5665, 2, S34},	

	/* round 4 */
[48]	{ 0xf4292244, 0, S41},	
	{ 0x432aff97, 7, S42},	
	{ 0xab9423a7, 14, S43},	
	{ 0xfc93a039, 5, S44},	
	{ 0x655b59c3, 12, S41},	
	{ 0x8f0ccc92, 3, S42},	
	{ 0xffeff47d, 10, S43},	
	{ 0x85845dd1, 1, S44},	
	{ 0x6fa87e4f, 8, S41},	
	{ 0xfe2ce6e0, 15, S42},	
	{ 0xa3014314, 6, S43},	
	{ 0x4e0811a1, 13, S44},	
	{ 0xf7537e82, 4, S41},	
	{ 0xbd3af235, 11, S42},	
	{ 0x2ad7d2bb, 2, S43},	
	{ 0xeb86d391, 9, S44},	
};

aggr MD5state
{
	uint len;
	uint state[4];
};

Arg *arg;
int debug;
Biobuf *b;

intern void encode(byte*, uint*, uint);
intern void decode(uint*, byte*, uint);
intern MD5state* md5(byte*, uint, byte*, MD5state*);
intern void sum(int, byte*);

void
main(int argc, byte **argv)
{
	int c, fd;

	b = Bopen("/fd/1", OWRITE);

	arg = arginit(argc, argv);
	while(c = argopt(arg))
		switch(c){
		case 'd':
			debug++;
		}

	if(arg->ac == 0)
		sum(0, nil);
	else for(c = 0; c < arg->ac; c++){
		fd = open(arg->av[c], OREAD);
		if(fd < 0){
			fprint(2, "md5sum: can't open %s: %r\n", arg->av[c]);
			continue;
		}
		sum(fd, arg->av[c]);
		close(fd);
	}
}

intern void
sum(int fd, byte *name)
{
	byte *buf;
	byte digest[16];
	int i, n;
	MD5state *s;

	b->flush();
	s = nil;
	n = 0;
	buf = malloc(256*64);
	for(;;){
		i = read(fd, buf+n, 128*64-n);
		if(i <= 0)
			break;
		n += i;
		if(n & 0x3f)
			continue;
		s = md5(buf, n, nil, s);
		n = 0;
	}
	md5(buf, n, digest, s);
	b->print("%.2x", digest[0::16]);
	if(name != nil)
		b->print("\t%s", name);
	b->print("\n");
	free(buf);
}

/*
 *  I require len to be a multiple of 64 for all but
 *  the last call
 */
intern MD5state*
md5(byte *p, uint len, byte *digest, MD5state *s)
{
	uint a, b, c, d, tmp;
	uint i, done;
	Table *t;
	byte *end;
	uint x[16];

	if(s == nil){
		s = malloc(sizeof(*s));
		if(s == nil)
			return nil;

		/* seed the state, these constants would look nicer big-endian */
		s->state[0] = 0x67452301;
		s->state[1] = 0xefcdab89;
		s->state[2] = 0x98badcfe;
		s->state[3] = 0x10325476;
	}
	s->len += len;

	i = len & 0x3f;
	if(i){
		done = 1;

		/* pad the input, assume there's room */
		if(i < 56)
			i = 56 - i;
		else
			i = 120 - i;
		if(i > 0){
			memset(p + len, 0, i);
			p[len] = 0x80;
		}
		len += i;

		/* append the count */
		x[0] = s->len<<3;
		x[1] = s->len>>29;
		encode(p+len, x, 8);
	} else
		done = 0;

	for(end = p+len; p < end; p += 64){
		a = s->state[0];
		b = s->state[1];
		c = s->state[2];
		d = s->state[3];

		decode(x, p, 64);
	
		for(i = 0; i < 64; i++){
			t = tab + i;
			switch(i>>4){
			case 0:
				a += (b & c) | (~b & d);
				break;
			case 1:
				a += (b & d) | (c & ~d);
				break;
			case 2:
				a += b ^ c ^ d;
				break;
			case 3:
				a += c ^ (b | ~d);
				break;
			}
			a += x[t->x] + t->sin;
			a = (a << t->rot) | (a >> (32 - t->rot));
			a += b;
	
			/* rotate variables */
			tmp = d;
			d = c;
			c = b;
			b = a;
			a = tmp;
		}

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

	/* return result */
	if(done){
		encode(digest, s->state, 16);
		free(s);
		return nil;
	}
	return s;
}

/*
 *	encodes input (uint) into output (byte). Assumes len is
 *	a multiple of 4.
 */
intern void
encode(byte *output, uint *input, uint len)
{
	uint x;
	byte *e;

	for(e = output + len; output < e;) {
		x = *input++;
		*output++ = x;
		*output++ = x >> 8;
		*output++ = x >> 16;
		*output++ = x >> 24;
	}
}

/*
 *	decodes input (byte) into output (uint). Assumes len is
 *	a multiple of 4.
 */
intern void
decode(uint *output, byte *input, uint len)
{
	byte *e;

	for(e = input+len; input < e; input += 4)
		*output++ = input[0] | (input[1] << 8) |
			(input[2] << 16) | (input[3] << 24);
}