/*
 * Copyright (c) 2008-2024 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License version 3.0 only,
 * as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * version 3.0 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3.0 along with this program. If not, see
 * <https://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <string.h>

#import "OFSHA1Hash.h"
#import "OFSecureData.h"

#import "OFHashAlreadyCalculatedException.h"
#import "OFHashNotCalculatedException.h"
#import "OFOutOfRangeException.h"

static const size_t digestSize = 20;
static const size_t blockSize = 64;

OF_DIRECT_MEMBERS
@interface OFSHA1Hash ()
- (void)of_resetState;
@end

#define F(a, b, c, d) ((d) ^ ((b) & ((c) ^ (d))))
#define G(a, b, c, d) ((b) ^ (c) ^ (d))
#define H(a, b, c, d) (((b) & (c)) | ((d) & ((b) | (c))))
#define I(a, b, c, d) ((b) ^ (c) ^ (d))

static OF_INLINE void
byteSwapVectorIfLE(uint32_t *vector, uint_fast8_t length)
{
#ifndef OF_BIG_ENDIAN
	for (uint_fast8_t i = 0; i < length; i++)
		vector[i] = OFByteSwap32(vector[i]);
#endif
}

static void
processBlock(uint32_t *state, uint32_t *buffer)
{
	uint32_t new[5];
	uint_fast8_t i;

	new[0] = state[0];
	new[1] = state[1];
	new[2] = state[2];
	new[3] = state[3];
	new[4] = state[4];

	byteSwapVectorIfLE(buffer, 16);

	for (i = 16; i < 80; i++) {
		uint32_t tmp = buffer[i - 3] ^ buffer[i - 8] ^
		    buffer[i - 14] ^ buffer[i - 16];
		buffer[i] = OFRotateLeft(tmp, 1);
	}

#define LOOP_BODY(f, k)							\
	{								\
		uint32_t tmp = OFRotateLeft(new[0], 5) +		\
		    f(new[0], new[1], new[2], new[3]) +			\
		    new[4] + k + buffer[i];				\
		new[4] = new[3];					\
		new[3] = new[2];					\
		new[2] = OFRotateLeft(new[1], 30);			\
		new[1] = new[0];					\
		new[0] = tmp;						\
	}

	for (i = 0; i < 20; i++)
		LOOP_BODY(F, 0x5A827999)
	for (; i < 40; i++)
		LOOP_BODY(G, 0x6ED9EBA1)
	for (; i < 60; i++)
		LOOP_BODY(H, 0x8F1BBCDC)
	for (; i < 80; i++)
		LOOP_BODY(I, 0xCA62C1D6)

#undef LOOP_BODY

	state[0] += new[0];
	state[1] += new[1];
	state[2] += new[2];
	state[3] += new[3];
	state[4] += new[4];
}

@implementation OFSHA1Hash
@synthesize calculated = _calculated;
@synthesize allowsSwappableMemory = _allowsSwappableMemory;

+ (size_t)digestSize
{
	return digestSize;
}

+ (size_t)blockSize
{
	return blockSize;
}

+ (instancetype)hashWithAllowsSwappableMemory: (bool)allowsSwappableMemory
{
	return [[[self alloc] initWithAllowsSwappableMemory:
	    allowsSwappableMemory] autorelease];
}

- (instancetype)initWithAllowsSwappableMemory: (bool)allowsSwappableMemory
{
	self = [super init];

	@try {
		_iVarsData = [[OFSecureData alloc]
			    initWithCount: sizeof(*_iVars)
		    allowsSwappableMemory: allowsSwappableMemory];
		_iVars = _iVarsData.mutableItems;
		_allowsSwappableMemory = allowsSwappableMemory;

		[self of_resetState];
	} @catch (id e) {
		[self release];
		@throw e;
	}

	return self;
}

- (instancetype)init
{
	OF_INVALID_INIT_METHOD
}

- (instancetype)of_init
{
	return [super init];
}

- (void)dealloc
{
	[_iVarsData release];

	[super dealloc];
}

- (size_t)digestSize
{
	return digestSize;
}

- (size_t)blockSize
{
	return blockSize;
}

- (id)copy
{
	OFSHA1Hash *copy = [[OFSHA1Hash alloc] of_init];

	copy->_iVarsData = [_iVarsData copy];
	copy->_iVars = copy->_iVarsData.mutableItems;
	copy->_allowsSwappableMemory = _allowsSwappableMemory;
	copy->_calculated = _calculated;

	return copy;
}

- (void)of_resetState
{
	_iVars->state[0] = 0x67452301;
	_iVars->state[1] = 0xEFCDAB89;
	_iVars->state[2] = 0x98BADCFE;
	_iVars->state[3] = 0x10325476;
	_iVars->state[4] = 0xC3D2E1F0;
}

- (void)updateWithBuffer: (const void *)buffer_ length: (size_t)length
{
	const unsigned char *buffer = buffer_;

	if (_calculated)
		@throw [OFHashAlreadyCalculatedException
		    exceptionWithObject: self];

	if (length > SIZE_MAX / 8)
		@throw [OFOutOfRangeException exception];

	_iVars->bits += (length * 8);

	while (length > 0) {
		size_t min = 64 - _iVars->bufferLength;

		if (min > length)
			min = length;

		memcpy(_iVars->buffer.bytes + _iVars->bufferLength,
		    buffer, min);
		_iVars->bufferLength += min;

		buffer += min;
		length -= min;

		if (_iVars->bufferLength == 64) {
			processBlock(_iVars->state, _iVars->buffer.words);
			_iVars->bufferLength = 0;
		}
	}
}

- (const unsigned char *)digest
{
	if (!_calculated)
		@throw [OFHashNotCalculatedException exceptionWithObject: self];

	return (const unsigned char *)_iVars->state;
}

- (void)calculate
{
	if (_calculated)
		@throw [OFHashAlreadyCalculatedException
		    exceptionWithObject: self];

	_iVars->buffer.bytes[_iVars->bufferLength] = 0x80;
	OFZeroMemory(_iVars->buffer.bytes + _iVars->bufferLength + 1,
	    64 - _iVars->bufferLength - 1);

	if (_iVars->bufferLength >= 56) {
		processBlock(_iVars->state, _iVars->buffer.words);
		OFZeroMemory(_iVars->buffer.bytes, 64);
	}

	_iVars->buffer.words[14] =
	    OFToBigEndian32((uint32_t)(_iVars->bits >> 32));
	_iVars->buffer.words[15] =
	    OFToBigEndian32((uint32_t)(_iVars->bits & 0xFFFFFFFF));

	processBlock(_iVars->state, _iVars->buffer.words);
	OFZeroMemory(&_iVars->buffer, sizeof(_iVars->buffer));
	byteSwapVectorIfLE(_iVars->state, 5);
	_calculated = true;
}

- (void)reset
{
	[self of_resetState];
	_iVars->bits = 0;
	OFZeroMemory(&_iVars->buffer, sizeof(_iVars->buffer));
	_iVars->bufferLength = 0;
	_calculated = false;
}
@end