#include <stdlib.h>
#include <string.h>
#include <stdio.h>
typedef unsigned int uint;
typedef unsigned char byte;
extern int enc64(char*,byte*,int);

/*
 *  rfc1321 requires that I include this.  The code is new.  The constants
 *  all come from the rfc (hence the copyright).  We trade a table for the
 *  macros in rfc.  The total size is a lot less.
 *  presotto@plan9.bell-labs.com  (with tweaks by ehg@netlib.bell-labs.com)
 *
 *	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 amounts 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
};

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

Table tab[] =
{
	/* round 1 */
	{ 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 */
	{ 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 */
	{ 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 */
	{ 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},	
};

typedef struct MD5state
{
	uint len;
	uint state[4];
}MD5state;
MD5state *nil;

int debug;
int hex;    /* print in hex?  (instead of default base64) */

void encode(byte*, uint*, uint);
void decode(uint*, byte*, uint);
MD5state* md5(byte*, uint, byte*, MD5state*);
void sum(FILE*, char*);

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

	argv++; argc--;
	if(argc>0 && strcmp(argv[0],"-d")==0){
		debug++;
		argv++; argc--;
	}

	if(argc>0 && strcmp(argv[0],"-x")==0){
		hex++;
		argv++; argc--;
	}

	if(argc == 0)
		sum(stdin,0);
	else for(c = 0; c < argc; c++){
		fd = fopen(argv[c],"r");
		if(fd==NULL){
			fprintf(stderr, "md5sum: can't open %s\n", argv[c]);
			continue;
		}
		sum(fd, argv[c]);
		fclose(fd);
	}
}

void
sum(FILE *fd, char *name)
{
	byte *buf;
	byte digest[16];
	char pr64[25];
	int i, n;
	MD5state *s;

	s = nil;
	n = 0;
	buf = calloc(256,64);
	for(;;){
		i = fread(buf+n, 1, 128*64-n, fd);
		if(i <= 0)
			break;
		n += i;
		if(n & 0x3f)
			continue;
		s = md5(buf, n, 0, s);
		n = 0;
	}
	md5(buf, n, digest, s);
	if(hex){
		for(i=0;i<16;i++) printf("%.2X", digest[i]);
	}else{
		enc64(pr64,digest,sizeof(digest));
		pr64[22] = '\0';  /* chop trailing == */
		printf("%s",pr64);
	}
	if(name)
		printf("\t%s", name);
	printf("\n");
	free(buf);
}

/*
 *  I require len to be a multiple of 64 for all but
 *  the last call
 */
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 = calloc(sizeof(*s),1);
		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 || len == 0){
		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.
 */
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.
 */
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);
}




typedef unsigned long ulong;
typedef unsigned char uchar;

static uchar t64d[256];
static char t64e[64];

static void
init64(void)
{
	int c, i;

	memset(t64d, 255, 256);
	memset(t64e, '=', 64);
	i = 0;
	for(c = 'A'; c <= 'Z'; c++){
		t64e[i] = c;
		t64d[c] = i++;
	}
	for(c = 'a'; c <= 'z'; c++){
		t64e[i] = c;
		t64d[c] = i++;
	}
	for(c = '0'; c <= '9'; c++){
		t64e[i] = c;
		t64d[c] = i++;
	}
	t64e[i] = '+';
	t64d['+'] = i++;
	t64e[i] = '/';
	t64d['/'] = i;
}

int
dec64(uchar *out, char *in, int n)
{
	ulong b24;
	uchar *start = out;
	int i, c;

	if(t64e[0] == 0)
		init64();

	b24 = 0;
	i = 0;
	while(n-- > 0){
		c = t64d[*in++];
		if(c == 255)
			continue;
		switch(i){
		case 0:
			b24 = c<<18;
			break;
		case 1:
			b24 |= c<<12;
			break;
		case 2:
			b24 |= c<<6;
			break;
		case 3:
			b24 |= c;
			*out++ = b24>>16;
			*out++ = b24>>8;
			*out++ = b24;
			i = -1;
			break;
		}
		i++;
	}
	switch(i){
	case 2:
		*out++ = b24>>16;
		break;
	case 3:
		*out++ = b24>>16;
		*out++ = b24>>8;
		break;
	}
	*out = 0;
	return out - start;
}

int
enc64(char *out, uchar *in, int n)
{
	int i;
	ulong b24;
	char *start = out;

	if(t64e[0] == 0)
		init64();
	for(i = n/3; i > 0; i--){
		b24 = (*in++)<<16;
		b24 |= (*in++)<<8;
		b24 |= *in++;
		*out++ = t64e[(b24>>18)];
		*out++ = t64e[(b24>>12)&0x3f];
		*out++ = t64e[(b24>>6)&0x3f];
		*out++ = t64e[(b24)&0x3f];
	}

	switch(n%3){
	case 2:
		b24 = (*in++)<<16;
		b24 |= (*in)<<8;
		*out++ = t64e[(b24>>18)];
		*out++ = t64e[(b24>>12)&0x3f];
		*out++ = t64e[(b24>>6)&0x3f];
		break;
	case 1:
		b24 = (*in)<<16;
		*out++ = t64e[(b24>>18)];
		*out++ = t64e[(b24>>12)&0x3f];
		*out++ = '=';
		break;
	}
	*out++ = '=';
	*out = 0;
	return out - start;
}