filter.c

/**
 * This file is part of the Zephir.
 *
 * (c) Phalcon Team <team@zephir-lang.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code. If you did not receive
 * a copy of the license it is available through the world-wide-web at the
 * following url: https://docs.zephir-lang.com/en/latest/license
 */

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

#include <ctype.h>

#include "php.h"
#include "php_ext.h"
#include "php_main.h"
#include <ext/standard/php_smart_string.h>
#include <ext/standard/php_math.h>
#include <ext/standard/html.h>

#include "kernel/main.h"
#include "kernel/memory.h"

#include <Zend/zend_exceptions.h>
#include <Zend/zend_interfaces.h>
#include <zend_smart_str.h>

/**
 * Filter alphanum string
 */
void zephir_filter_alphanum(zval *return_value, zval *param)
{
	unsigned int i;
	unsigned char ch;
	smart_str filtered_str = {0};
	zval copy;
	int use_copy = 0;

	if (Z_TYPE_P(param) != IS_STRING) {
		use_copy = zend_make_printable_zval(param, &copy);
		if (use_copy) {
			param = &copy;
		}
	}

	for (i = 0; i < Z_STRLEN_P(param); i++) {
		ch = Z_STRVAL_P(param)[i];
		if (ch == '\0') {
			break;
		}
		if (isalnum(ch)) {
			smart_str_appendc(&filtered_str, ch);
		}
	}

	if (use_copy) {
		zval_dtor(param);
	}

	smart_str_0(&filtered_str);

	if (filtered_str.s) {
		RETURN_STR(filtered_str.s);
	} else {
		RETURN_EMPTY_STRING();
	}
}

/**
 * Check if a string is encoded with ASCII or ISO-8859-1
 */
void zephir_is_basic_charset(zval *return_value, const zval *param)
{
	unsigned int i;
	unsigned int ch;
	int iso88591 = 0;

	for (i = 0; i < Z_STRLEN_P(param); i++) {
		ch = Z_STRVAL_P(param)[i];
		if (ch != '\0') {
			if (ch == 172 || (ch >= 128 && ch <= 159)) {
				continue;
			}
			if (ch >= 160 && ch <= 255) {
				iso88591 = 1;
				continue;
			}
		}
		RETURN_FALSE;
	}

	if (!iso88591) {
		RETURN_STRING("ASCII");
	}

	RETURN_STRING("ISO-8859-1");
}

static long zephir_unpack(char *data, int size, int issigned, int *map)
{
	long result;
	char *cresult = (char *) &result;
	int i;

	result = issigned ? -1 : 0;

	for (i = 0; i < size; i++) {
		cresult[map[i]] = *data++;
	}

	return result;
}

/**
 * Converts an unsigned long to a char*
 */
static inline char *zephir_longtohex(unsigned long value)
{
	static char digits[] = "0123456789abcdef";
	char buf[(sizeof(unsigned long) << 3) + 1];
	char *ptr, *end;

	end = ptr = buf + sizeof(buf) - 1;
	*ptr = '\0';
	do {
		*--ptr = digits[value & 0x0F];
		value >>= 4;
	} while (ptr > buf && value);

	return estrndup(ptr, end - ptr);
}

/**
 * Perform escaping of non-alphanumeric characters to different formats
 */
void zephir_escape_multi(zval *return_value, zval *param, const char *escape_char, unsigned int escape_length, char escape_extra, int use_whitelist)
{
	unsigned int i;
	zval copy;
	smart_str escaped_str = {0};
	char machine_little_endian, *hex;
	int big_endian_long_map[4];
	int use_copy = 0, machine_endian_check = 1;
	int issigned = 0;
	long value;

	if (Z_TYPE_P(param) != IS_STRING) {
		use_copy = zend_make_printable_zval(param, &copy);
		if (use_copy) {
			param = &copy;
		}
	}

	if (Z_STRLEN_P(param) <= 0) {
		RETURN_FALSE;
	}

	/**
	 * This is how the big_ending_long_map is calculated as in 'pack'
	 */
	machine_little_endian = ((char *) &machine_endian_check)[0];
	if (machine_little_endian) {
		big_endian_long_map[0] = 3;
		big_endian_long_map[1] = 2;
		big_endian_long_map[2] = 1;
		big_endian_long_map[3] = 0;
	} else {
		int size = sizeof(Z_LVAL_P(param));
		big_endian_long_map[0] = size - 4;
		big_endian_long_map[1] = size - 3;
		big_endian_long_map[2] = size - 2;
		big_endian_long_map[3] = size - 1;
	}

	/**
	 * The input must be a valid UTF-32 string
	 */
	if ((Z_STRLEN_P(param) % 4) != 0) {
		RETURN_FALSE;
	}

	for (i = 0; i < Z_STRLEN_P(param); i += 4) {

		issigned = Z_STRVAL_P(param)[i] & 0x80;

		value = 0;
		if (sizeof(long) > 4 && issigned) {
			value = ~INT_MAX;
		}

		value |= zephir_unpack(&Z_STRVAL_P(param)[i], 4, issigned, big_endian_long_map);
		if (sizeof(long) > 4) {
			value = (unsigned int) value;
		}

		/**
		 * CSS 2.1 section 4.1.3: "It is undefined in CSS 2.1 what happens if a
		 * style sheet does contain a character with Unicode codepoint zero."
		 */
		if (value == '\0') {
			RETURN_FALSE;
		}

		/**
		 * Alphanumeric characters are not escaped
		 */
		if (value < 123 && isalnum(value)) {
			smart_str_appendc(&escaped_str, (unsigned char) value);
			continue;
		}

		/**
		 * Chararters in the whitelist are left as they are
		 */
		if (use_whitelist) {
			switch (value) {
				case ' ':
				case '/':
				case '*':
				case '+':
				case '-':
				case '\t':
				case '\n':
				case '^':
				case '$':
				case '!':
				case '?':
				case '\\':
				case '#':
				case '}':
				case '{':
				case ')':
				case '(':
				case ']':
				case '[':
				case '.':
				case ',':
				case ':':
				case ';':
				case '_':
				case '|':
					smart_str_appendc(&escaped_str, (unsigned char) value);
					continue;
			}
		}

		/**
		 * Convert character to hexadecimal
		 */
		hex = zephir_longtohex(value);

		/**
		 * Append the escaped character
		 */
		smart_str_appendl(&escaped_str, escape_char, escape_length);
		smart_str_appendl(&escaped_str, hex, strlen(hex));
		if (escape_extra != '\0') {
			smart_str_appendc(&escaped_str, escape_extra);
		}

		efree(hex);
	}

	if (use_copy) {
		zval_dtor(param);
	}

	smart_str_0(&escaped_str);

	if (escaped_str.s) {
		RETURN_STR(escaped_str.s);
	} else {
		RETURN_EMPTY_STRING();
	}
}

/**
 * Escapes non-alphanumeric characters to \HH+space
 */
void zephir_escape_css(zval *return_value, zval *param)
{
	zephir_escape_multi(return_value, param, "\\", sizeof("\\")-1, ' ', 0);
}

/**
 * Escapes non-alphanumeric characters to \xHH+
 */
void zephir_escape_js(zval *return_value, zval *param)
{
	zephir_escape_multi(return_value, param, "\\x", sizeof("\\x")-1, '\0', 1);
}