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Tools_SafeEval.js
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Tools_SafeEval.js
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//! BEGIN_MODULE()
//! REPLACE_BY("// Copyright 2015-2018 Claude Petit, licensed under Apache License version 2.0\n", true)
// doodad-js - Object-oriented programming framework
// File: Tools_SafeEval.js - SafeEval tools
// Project home: https://github.com/doodadjs/
// Author: Claude Petit, Quebec city
// Contact: doodadjs [at] gmail.com
// Note: I'm still in alpha-beta stage, so expect to find some bugs or incomplete parts !
// License: Apache V2
//
// Copyright 2015-2018 Claude Petit
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! END_REPLACE()
//! IF_SET("mjs")
//! ELSE()
"use strict";
//! END_IF()
exports.add = function add(modules) {
modules = (modules || {});
modules['Doodad.Tools.SafeEval'] = {
version: /*! REPLACE_BY(TO_SOURCE(VERSION(MANIFEST("name")))) */ null /*! END_REPLACE()*/,
create: function create(root, /*optional*/_options, _shared) {
//===================================
// Get namespaces
//===================================
const doodad = root.Doodad,
types = doodad.Types,
tools = doodad.Tools,
locale = tools.Locale,
unicode = tools.Unicode,
safeEval = tools.SafeEval;
//===================================
// Internal
//===================================
const __Internal__ = {
deniedTokens: ['eval', 'arguments', 'this'],
constants: ['true', 'false', 'null', 'undefined', 'NaN', 'Infinity'],
allDigitsRegEx: /^([0-9]+[.]?[0-9]*([e][-+]?[0-9]+)?|0[xX]([0-9a-fA-F])+|0[bB]([01])+|0[oO]([0-7])+)$/,
};
//===================================
// Native functions
//===================================
//tools.complete(_shared.Natives, {
//});
__Internal__.validateExpression = function(expression, locals, globals, options) {
// TODO: Escape sequences
// TODO: String templates
const preventAssignment = types.get(options, 'preventAssignment', true),
allowFunctions = types.get(options, 'allowFunctions', false), // EXPERIMENTAL
allowNew = types.get(options, 'allowNew', false), // EXPERIMENTAL
allowRegExp = types.get(options, 'allowRegExp', false); // EXPERIMENTAL
if (root.DD_ASSERT) {
root.DD_ASSERT(types.isString(expression), "Invalid expression.");
root.DD_ASSERT(types.isNothing(locals) || types.isJsObject(locals), "Invalid locals.");
root.DD_ASSERT(types.isNothing(globals) || types.isArray(globals), "Invalid globals.");
};
let prevChr = '',
isString = false,
isEscape = false,
stringChar = null,
isAssignment = false,
isComment = false,
isCommentBlock = false,
isRegExp = false,
isRegExpFlags = false,
tokenName = '',
isGlobal = true,
isDot = false,
isFunction = false,
deniedTokens = [],
functionArgs = [],
brakets = 0,
waitArgs = false,
parentheses = 0,
isShift = false,
noPrevChr = false;
const maxSafeInteger = types.getSafeIntegerBounds().max;
const validateToken = function validateToken() {
if (tokenName) {
if (isGlobal) {
if (tools.indexOf(__Internal__.deniedTokens, tokenName) >= 0) {
throw new types.AccessDenied("Access to '~0~' is denied.", [tokenName]);
} else if (__Internal__.allDigitsRegEx.test(tokenName)) {
// Valid
} else if (allowNew && (tokenName === 'new')) {
// Valid
} else if (tools.indexOf(__Internal__.constants, tokenName) >= 0) {
// Valid
} else if (types.has(locals, tokenName)) {
// Valid
} else if (tools.indexOf(globals, tokenName) >= 0) {
// Valid
} else if (tools.indexOf(functionArgs, tokenName) >= 0) {
// Valid
} else if (isFunction && (brakets === 1) && (tokenName === 'return')) {
// Valid
} else if (tokenName === 'function') {
if (!allowFunctions) {
throw new types.AccessDenied("Functions are denied.");
};
if (isFunction) {
// For simplicity
throw new types.AccessDenied("Function in function is denied.");
};
isFunction = true;
waitArgs = true;
} else {
deniedTokens.push(tokenName);
};
};
tokenName = '';
};
};
const checkDenied = function checkDenied() {
if (deniedTokens.length) {
throw new types.AccessDenied("Access to '~0~' is denied.", [deniedTokens[0]]);
};
};
const curLocale = locale.getCurrent();
let chr = unicode.nextChar(expression);
while (chr) {
if (isString) {
if (isEscape) {
// Escaped char
isEscape = false;
} else if (chr.chr === '\\') {
// String escape
isEscape = true;
} else if (chr.chr === stringChar) {
// String closure
isString = false;
noPrevChr = true;
};
} else if (isRegExp) {
// RegExp
if (isEscape) {
// Escaped char
isEscape = false;
} else if (chr.chr === '\\') {
// Char escape
isEscape = true;
} else if (chr.chr === '/') {
// RegExp closure
isRegExp = false;
isRegExpFlags = true;
noPrevChr = true;
};
} else if (isCommentBlock) {
// Comment block
if ((prevChr === '*') && (chr.chr === '/')) {
// End comment block
isCommentBlock = false;
noPrevChr = true;
};
} else if (isAssignment && (chr.chr === '>')) {
// Arrow function
if (!allowFunctions) {
throw new types.AccessDenied("Functions are denied.");
};
if (isFunction) {
// For simplicity
throw new types.AccessDenied("Function in function is denied.");
};
isAssignment = false;
isFunction = true;
functionArgs = deniedTokens;
deniedTokens = [];
brakets = 0;
} else if ((isAssignment && (chr.chr !== '=')) || (isShift && (chr.chr === '='))) {
// Assignment
if (preventAssignment) {
throw new types.AccessDenied("Assignment is not allowed.");
};
checkDenied();
} else if (isComment && (chr.chr !== '\n') && (chr.chr !== '\r')) {
// Statement comment
} else if ((prevChr === '/') && (chr.chr === '/')) {
// Begin statement comment
validateToken();
isComment = true;
} else if ((prevChr === '/') && (chr.chr === '*')) {
// Begin comment block
validateToken();
isCommentBlock = true;
} else if (isGlobal && !tokenName && (prevChr === '/')) {
// Begin RegExp
if (!allowRegExp) {
// For simplicity
throw new types.AccessDenied("Regular expressions are not allowed.");
};
isRegExp = true;
if (chr.chr === '\\') {
isEscape = true;
};
} else if (unicode.isSpace(chr.chr, curLocale)) {
// Space
validateToken();
isDot = false;
isGlobal = true;
isRegExpFlags = false;
} else if ((chr.chr === ';') || (chr.chr === '\n') || (chr.chr === '\r')) { // End of statement
if (isComment && (chr.chr === ';')) {
// ';' is part of the comment
} else {
isComment = false;
isRegExpFlags = false;
validateToken();
checkDenied();
if (!isDot || (chr.chr === ';')) {
isGlobal = true;
};
functionArgs = [];
};
} else if ((chr.chr === '$') || (chr.chr === '_') || unicode.isAlnum(chr.chr, curLocale)) {
if (!isRegExpFlags) {
// Token
tokenName += chr.chr;
};
} else if (chr.chr === '\\') {
// For simplicity
throw new types.AccessDenied("Escape sequences not allowed.");
} else if (chr.codePoint > 0x7F) {
// For simplicity
throw new types.AccessDenied("Invalid character.");
} else if (chr.chr === ':') {
tokenName = '';
isRegExpFlags = false;
} else {
validateToken();
isDot = false;
isGlobal = true;
isRegExpFlags = false;
isAssignment = false;
isShift = false;
if ((chr.chr === '"') || (chr.chr === "'")) {
// Begin String
checkDenied();
isString = true;
stringChar = chr.chr;
} else if (chr.chr === '`') {
// For simplicity.
checkDenied();
throw new types.AccessDenied("Template strings are denied.");
} else if ((chr.chr === '+') || (chr.chr === '-')) {
checkDenied();
if (prevChr === chr.chr) {
// Increment
if (preventAssignment) {
throw new types.AccessDenied("Increment operators are not allowed.");
};
};
} else if (((chr.chr === '<') || (chr.chr === '>')) && (prevChr === chr.chr)) {
// Potential shift assignment
isShift = true;
} else if ((chr.chr === '=') && ((prevChr !== '>') && (prevChr !== '<') && (prevChr !== '=') && (prevChr !== '!'))) {
// Potential assignment
isAssignment = true;
} else if (chr.chr === '.') {
checkDenied();
isDot = true;
isGlobal = false;
} else if (isFunction && (chr.chr === '{')) {
if (brakets >= maxSafeInteger) {
// Should not happen
throw new types.Error("Integer overflow.");
};
brakets++;
} else if (isFunction && (chr.chr === '}')) {
brakets--;
if (brakets <= 0) {
isFunction = false;
brakets = 0;
functionArgs = [];
};
} else if (chr.chr === '(') {
if (isFunction) {
if (waitArgs) {
if (parentheses >= maxSafeInteger) {
// Should not happen
throw new types.Error("Integer overflow.");
};
parentheses++;
} else {
checkDenied();
};
};
} else if (chr.chr === ')') {
if (isFunction) {
if (waitArgs) {
waitArgs = false;
parentheses = 0; // can't have more than one parenthese
functionArgs = deniedTokens;
deniedTokens = [];
} else {
checkDenied();
};
};
} else {
checkDenied();
};
};
if (noPrevChr) {
noPrevChr = false;
prevChr = '';
} else {
prevChr = chr.chr;
};
chr = chr.nextChar();
};
validateToken();
checkDenied();
};
__Internal__.createEvalFn = function createEvalFn(locals, globals) {
root.DD_ASSERT && root.DD_ASSERT(types.isNothing(locals) || types.isObject(locals), "Invalid locals object.");
if (types.isNothing(globals)) {
globals = [];
} else {
root.DD_ASSERT && root.DD_ASSERT(types.isArray(globals), "Invalid global names array.");
};
globals = tools.reduce(globals, function(locals, name) {
if (name in global) {
locals[name] = global[name];
};
return locals;
}, {});
locals = tools.nullObject(globals, locals);
if (types.isEmpty(locals)) {
return tools.eval;
} else {
return tools.createEval(types.keys(locals)).apply(null, types.values(locals));
};
};
safeEval.ADD('eval', root.DD_DOC(
//! REPLACE_IF(IS_UNSET('debug'), "null")
{
author: "Claude Petit",
revision: 8,
params: {
expression: {
type: 'string',
optional: false,
description: "An expression",
},
locals: {
type: 'object',
optional: true,
description: "Local variables.",
},
globals: {
type: 'arrayof(string)',
optional: true,
description: "List of allowed global variables.",
},
options: {
type: 'object',
optional: true,
description: "Options.",
/* TODO: Document them somewhere
preventAssignment: {
type: 'boolean',
optional: true,
description: "If 'true', will prevent assignment operators. Otherwise, it will allow them. Default is 'true'.",
},
allowFunctions: {
type: 'boolean',
optional: true,
description: "IMPORTANT: Experimental, please leave it to 'false' (the default), or report bugs... If 'true', will allow function declarations. Otherwise, it will prevent them. Default is 'false'.",
},
allowNew: {
type: 'boolean',
optional: true,
description: "IMPORTANT: Experimental, please leave it to 'false' (the default), or report bugs... If 'true', will allow the 'new' operator. Otherwise, it will prevent it. Default is 'false'.",
},
allowRegExp: {
type: 'boolean',
optional: true,
description: "IMPORTANT: Experimental, please leave it to 'false' (the default), or report bugs... If 'true', will allow regular expressions. Otherwise, it will prevent them. Default is 'false'.",
},
*/
},
},
returns: 'any',
description: "Evaluates a Javascript expression with some restrictions.",
}
//! END_REPLACE()
, function safeEval(expression, /*optional*/locals, /*optional*/globals, /*optional*/options) {
// NOTE: Caller functions should use "safeEvalCached" for performance issues (only when expressions are controlled and limited)
// Restrict access to locals (locals={...}) and globals (globals=[...]).
// Prevents access to my local variables and arguments.
// Optionally prevents assignments and increments
__Internal__.validateExpression(expression, locals, globals, options);
const evalFn = __Internal__.createEvalFn(locals, globals);
return evalFn(expression);
}));
__Internal__.symbolCachedSafeEvalFn = types.getSymbol('__SAFE_EVAL_FN__');
__Internal__.symbolCachedSafeEvalOptions = types.getSymbol('__SAFE_EVAL_OPTIONS__');
safeEval.ADD('evalCached', root.DD_DOC(
//! REPLACE_IF(IS_UNSET('debug'), "null")
{
author: "Claude Petit",
revision: 4,
params: {
evalCacheObject: {
type: 'object',
optional: false,
description: "An object to use as cache",
},
expression: {
type: 'string',
optional: false,
description: "An expression",
},
options: {
type: 'object',
optional: true,
description: "Options.",
},
},
returns: 'any',
description: "Evaluates a Javascript expression with some restrictions, with cache.",
}
//! END_REPLACE()
, function safeEvalCached(evalCacheObject, expression, /*optional*/options) {
// WARNING: If expressions are not controlled and limited, don't use this function because of memory overhead
// WARNING: Will always uses the same options for the same cache object
if (root.DD_ASSERT) {
root.DD_ASSERT(types.isJsObject(evalCacheObject), "Invalid cache object.");
root.DD_ASSERT(types.isString(expression), "Invalid expression.");
};
let locals = null,
globals = null;
let evalFn = evalCacheObject[__Internal__.symbolCachedSafeEvalFn];
if (evalFn) {
options = evalCacheObject[__Internal__.symbolCachedSafeEvalOptions];
locals = types.get(options, 'locals');
globals = types.get(options, 'globals');
} else {
locals = types.freezeObject(types.clone(types.get(options, 'locals')));
globals = types.freezeObject(types.clone(types.get(options, 'globals')));
options = types.freezeObject(tools.extend({}, options, {locals: locals, globals: globals}));
evalFn = __Internal__.createEvalFn(locals, globals);
types.setAttribute(evalCacheObject, __Internal__.symbolCachedSafeEvalFn, evalFn, {});
types.setAttribute(evalCacheObject, __Internal__.symbolCachedSafeEvalOptions, options, {});
};
expression = tools.trim(expression);
if ((expression !== __Internal__.symbolCachedSafeEvalFn) && (expression !== __Internal__.symbolCachedSafeEvalOptions)) {
if ((expression === '__proto__') || (expression === 'constructor')) {
__Internal__.validateExpression(expression, locals, globals, options);
return evalFn(expression);
} else if (types.has(evalCacheObject, expression)) {
return evalCacheObject[expression];
} else {
__Internal__.validateExpression(expression, locals, globals, options);
const result = evalFn(expression);
evalCacheObject[expression] = result;
return result;
};
} else {
__Internal__.validateExpression(expression, locals, globals, options);
};
return undefined;
}));
//===================================
// Init
//===================================
//return function init(/*optional*/options) {
//};
},
};
return modules;
};
//! END_MODULE()