/*
 *  SPL - The SPL Programming Language
 *  Copyright (C) 2004, 2005  Clifford Wolf <clifford@clifford.at>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  This is based on the Public Domain SHA-1 implementation by Steve Reid.
 *
 *  sha1.c: An implementation of the SHA-1 algorithm.
 *
 */

#define _GNU_SOURCE

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

// MacOS X has __BYTE_ORDER defined but no endian.h.
// Win32 (MINGW) and BSD systems also show the behavior.
#if !defined USEMACOSXAPI && !defined USEWIN32API && !defined USEBSDAPI && !defined USEIRIXAPI
#  include <endian.h>
#endif

#include "spl.h"

typedef struct {
	unsigned long state[5];
	unsigned long count[2];
	unsigned char buffer[64];
} SHA1_CTX;

static void SHA1Transform(unsigned long state[5], unsigned char buffer[64]);
static void SHA1Init(SHA1_CTX* context);
static void SHA1Update(SHA1_CTX* context, unsigned char* data, unsigned int len);
static void SHA1Final(unsigned char digest[20], SHA1_CTX* context);

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

/* blk0() and blk() perform the initial expand. */
/* I got the idea of expanding during the round function from SSLeay */
#if __BYTE_ORDER == __LITTLE_ENDIAN
#define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) \
    |(rol(block->l[i],8)&0x00FF00FF))
#elif __BYTE_ORDER == __BIG_ENDIAN
#define blk0(i) block->l[i]
#else
#  error __BYTE_ORDER is not defined (should be __LITTLE_ENDIAN or __BIG_ENDIAN)
#endif
#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))

/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);


/* Hash a single 512-bit block. This is the core of the algorithm.
 */
static void SHA1Transform(unsigned long state[5], unsigned char buffer[64])
{
	unsigned long a, b, c, d, e;
	typedef union {
		unsigned char c[64];
		unsigned long l[16];
	} CHAR64LONG16;
	CHAR64LONG16* block;

	static unsigned char workspace[64];
	block = (CHAR64LONG16*)workspace;
	memcpy(block, buffer, 64);

	/* Copy context->state[] to working vars */
	a = state[0];
	b = state[1];
	c = state[2];
	d = state[3];
	e = state[4];

	/* 4 rounds of 20 operations each. Loop unrolled. */
	R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
	R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
	R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
	R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
	R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
	R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
	R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
	R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
	R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
	R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
	R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
	R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
	R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
	R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
	R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
	R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
	R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
	R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
	R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
	R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);

	/* Add the working vars back into context.state[] */
	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
	state[4] += e;

	/* Wipe variables */
	a = b = c = d = e = 0;
}


/* SHA1Init - Initialize new context
 */
static void SHA1Init(SHA1_CTX* context)
{
	/* SHA1 initialization constants */
	context->state[0] = 0x67452301;
	context->state[1] = 0xEFCDAB89;
	context->state[2] = 0x98BADCFE;
	context->state[3] = 0x10325476;
	context->state[4] = 0xC3D2E1F0;
	context->count[0] = context->count[1] = 0;
}


/* Run your data through this.
 */
static void SHA1Update(SHA1_CTX* context, unsigned char* data, unsigned int len)
{
	unsigned int i, j;

	j = (context->count[0] >> 3) & 63;
	if ((context->count[0] += len << 3) < (len << 3)) context->count[1]++;
	context->count[1] += (len >> 29);
	if ((j + len) > 63) {
		memcpy(&context->buffer[j], data, (i = 64-j));
		SHA1Transform(context->state, context->buffer);
		for ( ; i + 63 < len; i += 64) {
			SHA1Transform(context->state, &data[i]);
		}
		j = 0;
	}
	else i = 0;
	memcpy(&context->buffer[j], &data[i], len - i);
}


/* Add padding and return the message digest.
 */
static void SHA1Final(unsigned char digest[20], SHA1_CTX* context)
{
	unsigned long i, j;
	unsigned char finalcount[8];

	for (i = 0; i < 8; i++) {
		finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
				>> ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
	}
	SHA1Update(context, (unsigned char *)"\200", 1);
	while ((context->count[0] & 504) != 448) {
		SHA1Update(context, (unsigned char *)"\0", 1);
	}
	SHA1Update(context, finalcount, 8);  /* Should cause a SHA1Transform() */
	for (i = 0; i < 20; i++) {
		digest[i] = (unsigned char)
				((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
	}

	/* Wipe variables */
	i = j = 0;
	memset(context->buffer, 0, 64);
	memset(context->state, 0, 20);
	memset(context->count, 0, 8);
	memset(&finalcount, 0, 8);

	/* make SHA1Transform overwrite it's own static vars */
	SHA1Transform(context->state, context->buffer);
}

void spl_sha1(unsigned char *buffer, unsigned int buffer_len, unsigned char *digest)
{
	SHA1_CTX context;
	SHA1Init(&context);
	SHA1Update(&context, buffer, buffer_len);
	SHA1Final(digest, &context);
}

#ifdef SPL_TEST_SHA1_MAIN
// gcc -DSPL_TEST_SHA1_MAIN=1 -std=c99 -Wall -o sha1_test sha1.c && ./sha1_test

static void sha1_test(unsigned char *buffer, unsigned int buffer_len)
{
	unsigned char digest[20];
	spl_sha1(buffer, buffer_len, digest);

	for (int i=0; i<20; i++)
		printf("%s%s%02X", i == 0 ? " " : "", i%4 == 0 ? " " : "", digest[i]);
	printf("\n");
}

int main()
{
	unsigned char test_data1[] = "abc";
	unsigned char test_data2[] = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";
	unsigned char test_data3[1000001];

	for (int i=0; i<1000000; i++) test_data3[i] = 'a';
	test_data3[1000000] = 0;

	printf("\nSHA-1 Test Vectors from FIPS PUB 180-1:\n");

	printf("\n\"abc\"\n");
	printf("  A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D\n");
	sha1_test(test_data1, sizeof(test_data1)-1);

	printf("\n\"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq\"\n");
	printf("  84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1\n");
	sha1_test(test_data2, sizeof(test_data2)-1);

	printf("\nA million repetitions of \"a\"\n");
	printf("  34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F\n");
	sha1_test(test_data3, sizeof(test_data3)-1);

	printf("\n");
	return 0;
}

#endif