/*
  +----------------------------------------------------------------------+
  | Suhosin Version 1                                                    |
  +----------------------------------------------------------------------+
  | Copyright (c) 2006-2007 The Hardened-PHP Project                     |
  | Copyright (c) 2007-2016 SektionEins GmbH                             |
  +----------------------------------------------------------------------+
  | This source file is subject to version 3.01 of the PHP license,      |
  | that is bundled with this package in the file LICENSE, and is        |
  | available through the world-wide-web at the following url:           |
  | http://www.php.net/license/3_01.txt                                  |
  | If you did not receive a copy of the PHP license and are unable to   |
  | obtain it through the world-wide-web, please send a note to          |
  | license@php.net so we can mail you a copy immediately.               |
  +----------------------------------------------------------------------+
  | Authors: Stefan Esser <sesser@sektioneins.de>                        |
  |          Ben Fuhrmannek <ben.fuhrmannek@sektioneins.de>              |
  +----------------------------------------------------------------------+
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "php.h"
#include "php_suhosin7.h"
#include "ext/standard/base64.h"
// #include "sha256.h"
#include "ext/hash/php_hash.h"
#include "ext/hash/php_hash_sha.h"

// TODO: IPv6 handling

static void suhosin_get_ipv4(char *buf)
{
	char *raddr = suhosin_getenv(ZEND_STRL("REMOTE_ADDR"));
	int i;


	if (raddr == NULL) {
		memset(buf, 0, 4);
		return;
	}
	
	for (i=0; i<4; i++) {
		if (raddr[0] == 0) {
			buf[i] = 0;
		} else {
			buf[i] = strtol(raddr, &raddr, 10);
			if (raddr[0] == '.') {
				raddr++;
			}
		}
	}
}

zend_string *suhosin_encrypt_string(char *str, int len, char *var, int vlen, char *key)
{
	int padded_len, i, slen;
	unsigned char *crypted, *tmp;
	unsigned int check = 0x13579BDF;
	
	if (str == NULL) {
		return NULL;
	}
	
	if (len == 0) {
		return ZSTR_EMPTY_ALLOC();
	}

	suhosin_aes_gkey(4, 8, key);

	padded_len = ((len+15) & ~0xF);
	crypted = emalloc(16+padded_len+1);
	memset(crypted, 0xff, 16+padded_len+1);
	memcpy(crypted+16, str, len+1);

	/* calculate check value */
	for (i = 0; i < vlen; i++) {
		check = (check << 3) | (check >> (32-3));
		check += check << 1;
		check ^= (unsigned char)var[i];
	}
	for (i = 0; i < len; i++) {
		check = (check << 3) | (check >> (32-3));
		check += check << 1;
		check ^= (unsigned char)str[i];
	}
	
	/* store ip value */
	suhosin_get_ipv4((char *)crypted + 4);
	
	/* store check value */
	crypted[8] = check & 0xff;
	crypted[9] = (check >> 8) & 0xff;
	crypted[10] = (check >> 16) & 0xff;
	crypted[11] = (check >> 24) & 0xff;

	/* store original length */
	crypted[12] = len & 0xff;
	crypted[13] = (len >> 8) & 0xff;
	crypted[14] = (len >> 16) & 0xff;
	crypted[15] = (len >> 24) & 0xff;
	
	for (i = 0, tmp = crypted; i < padded_len + 16; i += 16, tmp += 16) {
		if (i > 0) {
			int j;
			for (j=0; j<16; j++) tmp[j] ^= tmp[j-16];
		}
		suhosin_aes_encrypt((char *)tmp);
	}
	
	zend_string *zs = php_base64_encode(crypted, padded_len+16);
	efree(crypted);
	// slen=strlen((char *)tmp);
	for (i = 0; i < ZSTR_LEN(zs); i++) {
		switch (ZSTR_VAL(zs)[i]) {
		case '/': ZSTR_VAL(zs)[i]='-'; break;
		case '=': ZSTR_VAL(zs)[i]='.'; break;
		case '+': ZSTR_VAL(zs)[i]='_'; break;
		}
	}
	return zs;
// return NULL;
}

zend_string *suhosin_decrypt_string(char *str, int padded_len, char *var, int vlen, char *key, int check_ra)
{
	SDEBUG("decrypting string |%s|", str);
	int i;
	unsigned int check = 0x13579BDF;
	
	if (str == NULL) {
		return NULL;
	}
	
	if (padded_len == 0) {
		return ZSTR_EMPTY_ALLOC();
	}
	suhosin_aes_gkey(4, 8, key);

	for (i = 0; i < padded_len; i++) {
		switch (str[i]) {
			case '-': str[i]='/'; break;
			case '.': str[i]='='; break;
			case '_': str[i]='+'; break;
		}
	}
	
	zend_string *decrypted_zs = php_base64_decode((unsigned char *)str, padded_len);
	if (decrypted_zs == NULL) {
		return NULL;
	}

	unsigned char *decrypted = (unsigned char*)ZSTR_VAL(decrypted_zs);
	int len = ZSTR_LEN(decrypted_zs);
	SDEBUG("len=%d", len);
	if (len < 2*16 || (len % 16) != 0) {
		goto error_out;
	}
	
	unsigned char *tmp;
	for (i = len - 16, tmp = decrypted + i; i >= 0; i -= 16, tmp -= 16) {
		suhosin_aes_decrypt((char *)tmp);
		if (i > 0) {
			int j;
			for (j=0; j<16; j++) tmp[j] ^= tmp[j-16];
		}
	}
	SDEBUG("tmp=%s", tmp);
	/* retrieve orig_len */
	int o_len = decrypted[15];
	o_len <<= 8;
	o_len |= decrypted[14];
	o_len <<= 8;
	o_len |= decrypted[13];
	o_len <<= 8;
	o_len |= decrypted[12];
	
	if (o_len < 0 || o_len > len-16) {
		goto error_out;
	}

	/* calculate check value */
	for (i = 0; i<vlen; i++) {
		check = (check << 3) | (check >> (32-3));
		check += check << 1;
		check ^= (unsigned char)var[i];
	}
	for (i = 0; i<o_len; i++) {
		check = (check << 3) | (check >> (32-3));
		check += check << 1;
		check ^= decrypted[16+i];
	}
	
	/* check value */
	int invalid = (decrypted[8] != (check & 0xff)) ||
		(decrypted[9] != ((check >> 8) & 0xff)) ||
		(decrypted[10] != ((check >> 16) & 0xff)) ||
		(decrypted[11] != ((check >> 24) & 0xff));
	
	/* check IP */
	if (check_ra) {
		if (check_ra > 4) {
			check_ra = 4;
		}
		char buf[4];
		suhosin_get_ipv4(&buf[0]);
		if (memcmp(buf, decrypted+4, check_ra) != 0) {
			goto error_out;
		}
	}
	
	if (invalid) {
		goto error_out;
	}
	
	memmove(decrypted, decrypted+16, o_len);
	decrypted[o_len] = 0;
	ZSTR_LEN(decrypted_zs) = o_len;
	/* we do not realloc() here because 16 byte less 
	   is simply not worth the overhead */  
	return decrypted_zs;

error_out:
	SDEBUG("error_out");
	if (decrypted_zs) {
		zend_string_release(decrypted_zs);
	}
	return NULL;
}

char *suhosin_generate_key(char *key, zend_bool ua, zend_bool dr, long raddr, char *cryptkey)
{
	char *_ua = NULL;
	char *_dr = NULL;
	char *_ra = NULL;
	PHP_SHA256_CTX ctx;
	
	if (ua) {
		_ua = suhosin_getenv(ZEND_STRL("HTTP_USER_AGENT"));
	}
	
	if (dr) {
		_dr = suhosin_getenv(ZEND_STRL("DOCUMENT_ROOT"));
	}
	
	if (raddr > 0) {
		_ra = suhosin_getenv(ZEND_STRL("REMOTE_ADDR"));
	}
	
	SDEBUG("KEY: %s - UA: %s - DR: %s - RA: %s", key,_ua,_dr,_ra);
	
	PHP_SHA256Init(&ctx);
	if (key == NULL || *key == 0) {
		PHP_SHA256Update(&ctx, (unsigned char*)ZEND_STRL("D3F4UL7"));
	} else {
		PHP_SHA256Update(&ctx, (unsigned char*)key, strlen(key));
	}
	if (_ua) {
		PHP_SHA256Update(&ctx, (unsigned char*)_ua, strlen(_ua));
	}
	if (_dr) {
		PHP_SHA256Update(&ctx, (unsigned char*)_dr, strlen(_dr));
	}
	if (_ra) {
		if (raddr >= 4) {
			PHP_SHA256Update(&ctx, (unsigned char*)_ra, strlen(_ra));
		} else {
			long dots = 0;
			char *tmp = _ra;
			
			while (*tmp) {
				if (*tmp == '.') {
					dots++;
					if (dots == raddr) {
						break;
					}
				}
				tmp++;
			}
			PHP_SHA256Update(&ctx, (unsigned char*)_ra, tmp-_ra);
		}
	}
	PHP_SHA256Final((unsigned char *)cryptkey, &ctx);
	cryptkey[32] = 0; /* uhmm... not really a string */
	
	return cryptkey;
}