/*
 * Copyright (C) 2005-2006 Martin Willi
 * Copyright (C) 2005 Jan Hutter
 * Hochschule fuer Technik Rapperswil
 * 
 * Ported from Steve Reid's <steve@edmweb.com> implementation
 * "SHA1 in C" found in strongSwan.
 *
 * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * 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.
 *
 * $Id: sha1_hasher.c 4308 2008-08-28 10:57:24Z martin $
 */

#include <string.h>
#include <arpa/inet.h>

#include "sha1_hasher.h"

/*
 * ugly macro stuff
 */ 
#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

#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 "Endianness not defined!"
#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);


typedef struct private_sha1_hasher_t private_sha1_hasher_t;

/**
 * Private data structure with hasing context.
 */
struct private_sha1_hasher_t {
	/**
	 * Public interface for this hasher.
	 */
	sha1_hasher_t public;
	
	/*
	 * State of the hasher. Shared with sha1_prf.c, do not change it!!!
	 */
	u_int32_t state[5];
    u_int32_t count[2];
    u_int8_t buffer[64];
};

/* 
 * Hash a single 512-bit block. This is the core of the algorithm. *
 */
static void SHA1Transform(u_int32_t state[5], const unsigned char buffer[64])
{
	u_int32_t a, b, c, d, e;
	typedef union {
    	u_int8_t c[64];
    	u_int32_t l[16];
	} CHAR64LONG16;
	CHAR64LONG16 block[1];  /* use array to appear as a pointer */
    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;
    memset(block, '\0', sizeof(block));
}

/**
 * Run your data through this. Also used in sha1_prf.
 */
void SHA1Update(private_sha1_hasher_t* this, u_int8_t *data, u_int32_t len)
{
	u_int32_t i;
	u_int32_t j;

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


/* 
 * Add padding and return the message digest. 
 */
static void SHA1Final(private_sha1_hasher_t *this, u_int8_t *digest)
{
	u_int32_t i;
	u_int8_t finalcount[8];
	u_int8_t c;

    for (i = 0; i < 8; i++) 
    {
        finalcount[i] = (u_int8_t)((this->count[(i >= 4 ? 0 : 1)]
         >> ((3-(i & 3)) * 8) ) & 255);  /* Endian independent */
    }
    c = 0200;
    SHA1Update(this, &c, 1);
    while ((this->count[0] & 504) != 448) 
    {
		c = 0000;
        SHA1Update(this, &c, 1);
    }
    SHA1Update(this, finalcount, 8);  /* Should cause a SHA1Transform() */
    for (i = 0; i < 20; i++) 
    {
        digest[i] = (u_int8_t)((this->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
    }
}

/**
 * Implementation of hasher_t.reset.
 */
static void reset(private_sha1_hasher_t *this)
{
	this->state[0] = 0x67452301;
    this->state[1] = 0xEFCDAB89;
    this->state[2] = 0x98BADCFE;
    this->state[3] = 0x10325476;
    this->state[4] = 0xC3D2E1F0;
    this->count[0] = 0;
    this->count[1] = 0;
}

/**
 * Implementation of hasher_t.get_hash.
 */
static void get_hash(private_sha1_hasher_t *this, chunk_t chunk, u_int8_t *buffer)
{
	SHA1Update(this, chunk.ptr, chunk.len);
	if (buffer != NULL)
	{
		SHA1Final(this, buffer);
		reset(this);
	}
}

/**
 * Implementation of hasher_t.allocate_hash.
 */
static void allocate_hash(private_sha1_hasher_t *this, chunk_t chunk, chunk_t *hash)
{
	SHA1Update(this, chunk.ptr, chunk.len);
	if (hash != NULL)
	{	
		hash->ptr = malloc(HASH_SIZE_SHA1);
		hash->len = HASH_SIZE_SHA1;
		
		SHA1Final(this, hash->ptr);
		reset(this);
	}
}
	
/**
 * Implementation of hasher_t.get_hash_size.
 */
static size_t get_hash_size(private_sha1_hasher_t *this)
{
	return HASH_SIZE_SHA1;
}

/**
 * Implementation of hasher_t.destroy.
 */
static void destroy(private_sha1_hasher_t *this)
{
	free(this);
}

/*
 * Described in header.
 */
sha1_hasher_t *sha1_hasher_create(hash_algorithm_t algo)
{
	private_sha1_hasher_t *this;
	if (algo != HASH_SHA1)
	{
		return NULL;
	}
	this = malloc_thing(private_sha1_hasher_t);
	this->public.hasher_interface.get_hash = (void (*) (hasher_t*, chunk_t, u_int8_t*))get_hash;
	this->public.hasher_interface.allocate_hash = (void (*) (hasher_t*, chunk_t, chunk_t*))allocate_hash;
	this->public.hasher_interface.get_hash_size = (size_t (*) (hasher_t*))get_hash_size;
	this->public.hasher_interface.reset = (void (*) (hasher_t*))reset;
	this->public.hasher_interface.destroy = (void (*) (hasher_t*))destroy;
	
	/* initialize */
	reset(this);
	
	return &(this->public);
}