sbx

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Run untrusted code as a VM in a child process

sbx allows you to run untrusted code in a more secure manner than simply using eval() or function(). To accomplish this, a child process is forked and untrusted code is run in vm with its own context. Inside the vm the untrusted code is wrapped in a try/catch inside an anonymous function in order to capture exceptions and output. Upon completion the context is returned to the user via callback or promise

Notes:

• Code is run inside an anonymous function and should be written as such
• Reserved variables _result, _exception, and _stdout are added to the context and should not be set by untrusted code
• 'use strict' statements are removed from untrusted code as they cause exceptions for passed context variables

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• WIKI
• Change Log
• v1.x.x Documentation

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Documentation

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API

sbx.vm( code, [options], [callback] )

• code {String} - string of untrusted Javascript to run.
• [options] {Object} - Options hash
  • [context] {Object} - Hash of key/value pairs that will be passed to the vm and are available to the untrusted code. previously variables
  • [lockdown=true] {Boolean} - If false, require statements will be allowed in order to use external modules
  • [timeout] {Number} - Time in milliseconds before the VM times out
  • [transform] {Function} - A function with the signature transform (code, options) that should return a string of transformed code. This can be used to transform ES6 code using babel see example
  • [parseImports=false] {Boolean} - Parse ES6+ import statements. Should be used with an ES6 source transform function and lockdown=false
• [callback] {Function} - Error first callback with signature callback(error, context)

Returns

Promise That resolves to an SBXContext

Types

SBXContext

• _result {any} - The return result of the executed code
• _exception {Object} - A hash containing the error message, stack trace, and scope of where the exception was caught (the child_process or the vm)
• _stdout {Array} - An array of stringified values from any calls made by sbx.log() inside the vm
• [context variables] {any} - Updated context variables

Capturing stdout

All arguments to console methods log, error, info, trace, and warn are automatically added as items in the _stdout context variable

You may also use the sbx.log method which is an alias for console.log

Example

var sbx = require('sbx')
 
var code = 'x++; console.log(\'I like the number\', x);'
 
var options = {
  context: { x: 7 },
  timeout: 100
}
 
var callback = function(error, context) {
  if (error) return console.error(error)
  console.log('The value of x = ', context.x)
}
 
sbx.vm(code, options, callback)
 
// > I like the number 8
// > The value of x = 8

Example with external module and promise result

var sbx = require('sbx')
 
var code      = 'var _ = require("lodash"); x = _.uniq(x); return x;'
 
var options = {
  context: { x: [1,1,2,2,3,4,5,6,6] },
  lockdown: false
}
 
sbx.vm(code, options).then(function (context) {
  console.log('The value of x = ', context.x, false)
  console.log(context._result)
}).catch(function (error) {
  console.error(error)
})
 
// > The value of x = [1, 2, 3, 4, 5, 6]
// > [1, 2, 3, 4, 5, 6]

Example with es2015 transform via babel + logging

var babel = require('babel-core')
var sbx = require('sbx')
 
var code = 'let fn = (msg) => msg\nsbx.log(message)\nreturn fn(message)'
 
var options = {
  context: { message: 'test' },
  transform: function (code, opts) {
    return babel.transform(code, {
      presets: ['es2015', 'stage-2'],
      plugins: ['transform-runtime']
    }).code
  }
}
 
sbx.vm(code, options).then(function(context) {
  console.log('Result = ', context._result)
  console.log(context._stdout)
})
 
// > Result = test
// > ['test']