/*
 * Copyright (C) Tildeslash Ltd. All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License version 3.
 *
 * 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 Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 *
 * You must obey the GNU Affero General Public License in all respects
 * for all of the code used other than OpenSSL.  
 */
/*
 * Based on 100% Public Domain SHA-1 in C By Steve Reid <sreid@sea-to-sky.net>
 */

#include "config.h"

#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif

#ifdef HAVE_STRING_H
#include <string.h>
#endif

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "sha1.h"

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

/* blk0() and blk() perform the initial expand. */
#ifdef WORDS_BIGENDIAN
#define blk0(i) block->l[i]
#else
#define blk0(i) (block->l[i] = (rol(block->l[i],24)&0xFF00FF00) | (rol(block->l[i],8)&0x00FF00FF))
#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 sha1_transform(unsigned int state[5], const unsigned char buffer[64]) {
        unsigned int a, b, c, d, e;
        typedef union {
                unsigned char c[64];
                unsigned int l[16];
        } CHAR64LONG16;
        CHAR64LONG16* block;

        block = (CHAR64LONG16*)buffer;

        /* 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;
}


/* Initialize new context */
void sha1_init(sha1_context_t *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. */
void sha1_append(sha1_context_t *context, const unsigned char * data, const size_t len) {
        size_t 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));
                sha1_transform(context->state, context->buffer);
                for ( ; i + 63 < len; i += 64)
                        sha1_transform(context->state, data + i);
                j = 0;
        } else {
                i = 0;
        }
        memcpy(&context->buffer[j], &data[i], len - i);
}


/* Add padding and return the message digest. */
void sha1_finish(sha1_context_t *context, unsigned char digest[SHA1_DIGEST_SIZE]) {
        unsigned int i;
        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 */
        sha1_append(context, (unsigned char *)"\200", 1);
        while ((context->count[0] & 504) != 448)
                sha1_append(context, (unsigned char *)"\0", 1);
        sha1_append(context, finalcount, 8);  /* Should cause a sha1_transform() */
        for (i = 0; i < SHA1_DIGEST_SIZE; i++)
                digest[i] = (unsigned char)((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);

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