Hackable HTTP proxy for resiliency testing and simulated network conditions
# toxy [![Build Status](https://api.travis-ci.org/h2non/toxy.svg?branch=master&style=flat)](https://travis-ci.org/h2non/toxy) [![Code Climate](https://codeclimate.com/github/h2non/toxy/badges/gpa.svg)](https://codeclimate.com/github/h2non/toxy) [![NPM](https://img.shields.io/npm/v/toxy.svg)](https://www.npmjs.org/package/toxy) [![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg)](http://standardjs.com)

> **Not actively maintained, may not work with latest node.js runtimes**. If you are interested in maintaining toxy, please open an issue.

**Hackable HTTP proxy** to **simulate** server **failure scenarios**, **systems resiliency testing** and **unexpected network conditions**, built for [node.js](http://nodejs.org).

<img align="right" height="180" src="http://s8.postimg.org/ikc9jxllh/toxic.jpg" />

It was mainly designed for failure resistance testing, when toxy becomes particularly useful in order to cover fault tolerance and resiliency capabilities of a system, especially in [disruption-tolerant networks](https://en.wikipedia.org/wiki/Delay-tolerant_networking) and [service-oriented](http://microservices.io/patterns/index.html) architectures, where toxy may act as MitM proxy among services in order to inject failure.

toxy allows you to plug in [poisons](#poisons), optionally filtered by [rules](#rules), which essentially can intercept and alter the HTTP flow as you need, performing multiple evil actions in the middle of that process, such as limiting the bandwidth, delaying network packets, injecting network jitter latency or replying with a custom error or status code.
It primarily operates at L7, although it can simulate L3 network conditions.

toxy can be fluently used [programmatically](#programmatic-api) or via [HTTP API](#http-api).
It was built on top of [rocky](https://github.com/h2non/rocky), a full-featured middleware-oriented HTTP proxy, and it's also [pluggable](https://github.com/h2non/toxy/blob/master/examples/express.js) in [connect](https://github.com/senchalabs/connect)/[express](http://expressjs.com) as standard middleware.

Requires node.js +4.

## Contents

- [Features](#features)
- [Introduction](#introduction)
  - [Why toxy?](#why-toxy)
  - [Concepts](#concepts)
  - [How it works](#how-it-works)
- [Usage](#usage)
  - [Installation](#installation)
  - [Examples](#examples)
- [Benchmark](#benchmark)
- [Poisons](#poisons)
  - [Poisoning scopes](#poisoning-scopes)
  - [Poisoning phases](#poisoning-phases)
  - [Built-in poisons](#built-in-poisons)
    - [Latency](#latency)
    - [Inject response](#inject-response)
    - [Bandwidth](#bandwidth)
    - [Rate limit](#rate-limit)
    - [Slow read](#slow-read)
    - [Slow open](#slow-open)
    - [Slow close](#slow-close)
    - [Throttle](#throttle)
    - [Abort connection](#abort-connection)
    - [Timeout](#timeout)
  - [How to write poisons](#how-to-write-poisons)
- [Rules](#rules)
  - [Built-in rules](#built-in-rules)
    - [Probability](#probability)
    - [Time threshold](#time-threshold)
    - [Method](#method)
    - [Content Type](#content-type)
    - [Headers](#headers)
    - [Response headers](#response-headers)
    - [Body](#body)
    - [Response body](#response-body)
    - [Response status](#response-status)
  - [Third-party rules](#third-party-rules)
  - [How to write rules](#how-to-write-rules)
- [Programmatic API](#programmatic-api)
- [HTTP API](#http-api)
  - [Usage](#usage)
  - [Authorization](#authorization)
  - [API](#api)
  - [Programmatic API](#programmatic-api-1)
- [License](#license)

## Features

- Full-featured HTTP/S proxy (backed by [rocky](https://github.com/h2non/rocky) and [http-proxy](https://github.com/nodejitsu/node-http-proxy))
- Hackable and elegant programmatic API (inspired on connect/express)
- Admin HTTP API for external management and dynamic configuration
- Featured built-in router with nested configuration
- Hierarchical and composable poisoning with rule based filtering
- Hierarchical middleware layer (both global and route scopes)
- Easily augmentable via middleware (based on connect/express middleware)
- Supports both incoming and outgoing traffic poisoning
- Built-in poisons (bandwidth, error, abort, latency, slow read...)
- Rule-based poisoning (probabilistic, HTTP method, headers, body...)
- Supports third-party poisons and rules
- Built-in balancer and traffic interceptor via middleware
- Inherits API and features from [rocky](https://github.com/h2non/rocky)
- Compatible with connect/express (and most of their middleware)
- Able to run as standalone HTTP proxy

## Introduction

### Why toxy?

There're some other similar solutions like `toxy` in the market, but most of them do not provide a proper programmatic control and usually are not easy to hack, configure or are directly closed to extensibility.

Furthermore, the majority of those solutions only operates at TCP L3 level stack instead of providing high-level abstractions to cover common requirements in the specific domain and nature of the HTTP L7 protocol, like toxy tries to provide

toxy brings a powerful hackable and extensible solution with a convenient abstraction, but without losing a proper low-level interface capabilities to deal with HTTP protocol primitives easily.

toxy was designed based on the rules of composition, simplicity and extensibility.
Via its built-in hierarchical domain specific middleware layer you can easily augment toxy features to your own needs.

### Concepts

`toxy` introduces two directives: poisons and rules.

**Poisons** are the specific logic which infects an incoming or outgoing HTTP transaction (e.g: injecting a latency, replying with an error). One HTTP transaction can be poisoned by one or multiple poisons, and those poisons can be also configured to infect both global or route level traffic.

**Rules** are a kind of match validation filters that inspects an HTTP request/response in order to determine, given a certain rules, if the HTTP transaction should be poisoned or not (e.g: if headers matches, query params, method, body...).
Rules can be reused and applied to both incoming and outgoing traffic flows, including different scopes: global, route or poison level.

### How it works

```
↓  ( Incoming request )  ↓
↓          |||           ↓
↓    +-------------+     ↓
↓    | Toxy Router |     ↓ -> Match the incoming request
↓    +-------------+     ↓
↓          |||           ↓
↓ +--------------------+ ↓
↓ |   Incoming phase   | ↓ -> The proxy receives the request from the client
↓ |~~~~~~~~~~~~~~~~~~~~| ↓
↓ |  ----------------  | ↓
↓ |  |  Exec Rules  |  | ↓ -> Apply configured rules for the incoming request
↓ |  ----------------  | ↓
↓ |        |||         | ↓
↓ |  ----------------  | ↓
↓ |  | Exec Poisons |  | ↓ -> If all rules passed, then poison the HTTP flow
↓ |  ----------------  | ↓
↓ +~~~~~~~~~~~~~~~~~~~~+ ↓
↓        /      \        ↓
↓        \      /        ↓
↓ +--------------------+ ↓
↓ |  HTTP dispatcher   | ↓ -> Forward the HTTP traffic to the target server, either poisoned or not
↓ +--------------------+ ↓
↓        /      \        ↓
↓        \      /        ↓
↓ +--------------------+ ↓
↓ |   Outgoing phase   | ↓ -> Receives response from target server
↓ |~~~~~~~~~~~~~~~~~~~~| ↓
↓ |  ----------------  | ↓
↓ |  |  Exec Rules  |  | ↓ -> Apply configured rules for the outgoing request
↓ |  ----------------  | ↓
↓ |        |||         | ↓
↓ |  ----------------  | ↓
↓ |  | Exec Poisons |  | ↓ -> If all rules passed, then poison the HTTP flow before send it to the client
↓ |  ----------------  | ↓
↓ +~~~~~~~~~~~~~~~~~~~~+ ↓
↓          |||           ↓
↓ ( Send to the client ) ↓ -> Finally, send the request to the client, either poisoned or not
```

## Usage

### Installation

```
npm install toxy
```

### Examples

See [examples](https://github.com/h2non/toxy/tree/master/examples) directory for more use cases.

```js
var toxy = require('toxy')
var poisons = toxy.poisons
var rules = toxy.rules

// Create a new toxy proxy
var proxy = toxy()

// Default server to forward incoming traffic
proxy
  .forward('http://httpbin.org')

// Register global poisons and rules
proxy
  .poison(poisons.latency({ jitter: 500 }))
  .rule(rules.probability(25))

// Register multiple routes
proxy
  .get('/download/*')
  .forward('http://files.myserver.net')
  .poison(poisons.bandwidth({ bps: 1024 }))
  .withRule(rules.headers({'Authorization': /^Bearer (.*)$/i }))

// Infect outgoing traffic only (after the server replied properly)
proxy
  .get('/image/*')
  .outgoingPoison(poisons.bandwidth({ bps: 512 }))
  .withRule(rules.method('GET'))
  .withRule(rules.timeThreshold({ duration: 1000, threshold: 1000 * 10 }))
  .withRule(rules.responseStatus({ range: [ 200, 400 ] }))

proxy
  .all('/api/*')
  .poison(poisons.rateLimit({ limit: 10, threshold: 1000 }))
  .withRule(rules.method(['POST', 'PUT', 'DELETE']))
  // And use a different more permissive poison for GET requests
  .poison(poisons.rateLimit({ limit: 50, threshold: 1000 }))
  .withRule(rules.method('GET'))

// Handle the rest of the traffic
proxy
  .all('/*')
  .poison(poisons.slowClose({ delay: 1000 }))
  .poison(poisons.slowRead({ bps: 128 }))
  .withRule(rules.probability(50))

proxy.listen(3000)
console.log('Server listening on port:', 3000)
console.log('Test it:', 'http://localhost:3000/image/jpeg')
```

## Benchmark

See [toxy/benchmark](https://github.com/h2non/toxy/tree/master/benchmark) for details.

## Poisons

Poisons host specific logic which intercepts and mutates, wraps, modify and/or cancel an HTTP transaction in the proxy server.
Poisons can be applied to incoming or outgoing, or even both traffic flows (see [poison phases](#poisoning-phases)).

Poisons can be composed and reused for different HTTP scenarios.
They are executed in FIFO order and asynchronously.

### Poisoning scopes

`toxy` has a hierarchical design based on two different scopes: `global` and `route`.

**Global** scope points to all the incoming HTTP traffic received by the proxy server, regardless of the HTTP method or path.

**Route** scope points to any incoming traffic which matches with a specific HTTP verb and URI path.

Poisons can be plugged to both scopes, meaning you can operate with better accuracy and restrict the scope of the poisoning,
for instance, you might wanna apply a bandwidth limit poisoning only to
a certain routes, such as `/download` or `/images`.

See [routes.js](https://github.com/h2non/toxy/blob/master/examples/routes.js) for a featured example.

### Poisoning phases

Poisons can be plugged to incoming or outgoing traffic flows, or even both.

**Incoming** poisoning is applied when the traffic has been received by proxy
but it has not been forwarded to the target server yet.

**Outgoing** poisoning refers to the traffic that has been forwarded to the target server and
when proxy receives the response from it, but that response has not been sent to the client yet.

This means, essentially, that you can plug in your poisons to infect the HTTP traffic
before or after the request is forwarded to the target HTTP server or sent to the client.

This allows you apply a better and more accurated poisoning based on the request or server response.
For instance, given the nature of some poisons, like `inject error`,
you may want to enable it according to the target server response (e.g: some header is present or not).

See [poison-phases.js](https://github.com/h2non/toxy/blob/master/examples/poison-phases.js) for a featured example.

### Built-in poisons

#### Latency

<table>
<tr>
<td><b>Name</b></td><td>latency</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Infects the HTTP flow injecting a latency jitter in the response

**Arguments**:

- **options** `object`
  - **jitter** `number` - Jitter value in milliseconds
  - **max** `number` - Random jitter maximum value
  - **min** `number` - Random jitter minimum value

```js
toxy.poison(toxy.poisons.latency({ jitter: 1000 }))
// Or alternatively using a random value
toxy.poison(toxy.poisons.latency({ max: 1000, min: 100 }))
```

#### Inject response

<table>
<tr>
<td><b>Name</b></td><td>inject</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>false (only as incoming poison)</td>
</tr>
</table>

Injects a custom response, intercepting the request before sending it to the target server.
Useful to inject errors originated in the server.

**Arguments**:

- **options** `object`
  - **code** `number` - Response HTTP status code. Default `500`
  - **headers** `object` - Optional headers to send
  - **body** `mixed` - Optional body data to send. It can be a `buffer` or `string`
  - **encoding** `string` - Body encoding. Default to `utf8`

```js
toxy.poison(toxy.poisons.inject({
  code: 503,
  body: '{"error": "toxy injected error"}',
  headers: {'Content-Type': 'application/json'}
}))
```

#### Bandwidth

<table>
<tr>
<td><b>Name</b></td><td>bandwidth</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Limits the amount of bytes sent over the network in outgoing HTTP traffic for a specific time frame.

This poison is basically an alias to [throttle](#throttle).

**Arguments**:

- **options** `object`
  - **bytes** `number` - Amount of chunk of bytes to send. Default `1024`
  - **threshold** `number` - Packets time frame in milliseconds. Default `1000`

```js
toxy.poison(toxy.poisons.bandwidth({ bytes: 512 }))
```

#### Rate limit

<table>
<tr>
<td><b>Name</b></td><td>rateLimit</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Limits the amount of requests received by the proxy in a specific threshold time frame. Designed to test API limits. Exposes typical `X-RateLimit-*` headers.

Note that this is very simple rate limit implementation, indeed limits are stored in-memory, therefore are completely volatile.
There're a bunch of featured and consistent rate limiter implementations in [npm](https://www.npmjs.com/search?q=rate+limit) that you can plug in as poison. You might be also interested in [token bucket algorithm](http://en.wikipedia.org/wiki/Token_bucket).

**Arguments**:

- **options** `object`
  - **limit** `number` - Total amount of requests. Default to `10`
  - **threshold** `number` - Limit time frame in milliseconds. Default to `1000`
  - **message** `string` - Optional error message when limit is reached.
  - **code** `number` - HTTP status code when limit is reached. Default to `429`.

```js
toxy.poison(toxy.poisons.rateLimit({ limit: 5, threshold: 10 * 1000 }))
```

#### Slow read

<table>
<tr>
<td><b>Name</b></td><td>slowRead</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Reads incoming payload data packets slowly. Only valid for non-GET request.

**Arguments**:

- **options** `object`
  - **chunk** `number` - Packet chunk size in bytes. Default to `1024`
  - **threshold** `number` - Limit threshold time frame in milliseconds. Default to `1000`

```js
toxy.poison(toxy.poisons.slowRead({ chunk: 2048, threshold: 1000 }))
```

#### Slow open
Name: `slowOpen`

<table>
<tr>
<td><b>Name</b></td><td>slowOpen</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Delays the HTTP connection ready state.

**Arguments**:

- **options** `object`
  - **delay** `number` - Delay connection in milliseconds. Default to `1000`

```js
toxy.poison(toxy.poisons.slowOpen({ delay: 2000 }))
```

#### Slow close

<table>
<tr>
<td><b>Name</b></td><td>slowClose</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Delays the HTTP connection close signal (EOF).

**Arguments**:

- **options** `object`
  - **delay** `number` - Delay time in milliseconds. Default to `1000`

```js
toxy.poison(toxy.poisons.slowClose({ delay: 2000 }))
```

#### Throttle

<table>
<tr>
<td><b>Name</b></td><td>throttle</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Restricts the amount of packets sent over the network in a specific threshold time frame.

**Arguments**:

- **options** `object`
  - **chunk** `number` - Packet chunk size in bytes. Default to `1024`
  - **delay** `object` - Data chunk delay time frame in milliseconds. Default to `100`

```js
toxy.poison(toxy.poisons.throttle({ chunk: 2048, threshold: 1000 }))
```

#### Abort connection

<table>
<tr>
<td><b>Name</b></td><td>abort</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>false (only as incoming poison)</td>
</tr>
</table>

Aborts the TCP connection. From the low-level perspective, this will destroy the socket on the server, operating only at TCP level without sending any specific HTTP application level data.

**Arguments**:

- **options** `object`
  - **delay** `number` - Aborts TCP connection after waiting the given milliseconds. Default to `0`
  - **next** `boolean` - If `true`, the connection will be aborted if the target server takes more than the `delay` param time to reply. Default to `false`
  - **error** `Error` - Custom internal node.js error to use when destroying the socket. Default to `null`

```js
// Basic connection abort
toxy.poison(toxy.poisons.abort())
// Abort after a delay
toxy.poison(toxy.poisons.abort(1000))
// In this case, the socket will be closed if
// the target server takes more than
// 2 seconds to respond
toxy.poison(toxy.poisons.abort({ delay: 2000, next: true }))
```

#### Timeout

<table>
<tr>
<td><b>Name</b></td><td>timeout</td>
</tr>
<tr>
<td><b>Poisoning Phase</b></td><td>incoming / outgoing</td>
</tr>
<tr>
<td><b>Reaches the server</b></td><td>true</td>
</tr>
</table>

Defines a response timeout. Useful when forward to potentially slow servers.

**Arguments**:

- **milliseconds** `number` - Timeout limit in milliseconds

```js
toxy.poison(toxy.poisons.timeout(5000))
```

### How to write poisons

Poisons are implemented as standard middleware function with the same interface as connect/express middleware.

Some poisons are not trivial to implement so you've to be familiar with node.js [http](https://nodejs.org/api/http.html) module and its API.

Here's a simple example of a server latency poison:

```js
var toxy = require('toxy')

function customLatencyPoison (delay) {
  // We name the function since toxy uses it as identifier to get/disable/remove it in the future
  return function customLatency (req, res, next) {
    var timeout = setTimeout(process, delay)
    req.once('close', onClose)

    function onClose () {
      clearTimeout(timeout)
      next('client connection closed')
    }

    function process () {
      req.removeListener('close', onClose)
      next()
    }
  }
}

var proxy = toxy()

// Register and enable the poison
proxy
  .get('/foo')
  .poison(customLatencyPoison(2000))
```

You can optionally extend the build-in poisons with your own poisons:

```js
toxy.addPoison(customLatency)

// Then you can use it as a built-in poison
proxy
  .get('/foo')
  .poison(toxy.poisons.customLatency)
```

For featured real example, take a look to the [built-in poisons](https://github.com/h2non/toxy/tree/master/lib/poisons) implementation.

## Rules

Rules are simple validation filters which inspects an incoming or outgoing HTTP traffic in order to determine, given a certain rules (e.g: matches the method, headers, query params, body...), if the current HTTP transaction should be poisoned or not, based on the resolution value of the rule.

Rules are useful to compose, decouple and reuse logic among different scenarios of poisoning.
Rules can be applied to global, route or even poison scope, and it also applies to both [phases of poisoning](#poisoning-phases).

Rules are executed in FIFO order. Their evaluation logic is equivalent to `Array#every()` in JavaScript: all the rules must pass in order to proceed with the poisoning.

### Built-in rules

#### Probability

<table>
<tr>
<td><b>Name</b></td><td>probability</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>incoming / outgoing</td>
</tr>
</table>

Enables the rule by a random probabilistic. Useful for random poisoning.

**Arguments**:

- **percentage** `number` - Percentage of filtering. Default `50`

```js
var rule = toxy.rules.probability(85)
toxy.rule(rule)
```

#### Time threshold

<table>
<tr>
<td><b>Name</b></td><td>timeThreshold</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>incoming / outgoing</td>
</tr>
</table>

Simple rule to enable poisons based on a specific time threshold and duration.
For instance, you can enable a certain poisons during a specific amount of time (e.g: 1 second) within a time threshold (e.g: 1 minute).

**Arguments**:

- **options** `object`
  - **duration** `number` - Enable time interval in milliseconds. Default to `1000`
  - **threshold** `number` - Time threshold in milliseconds to wait before re-enable the poisoning. Default to `10000`

```js
// Enable the poisoning only 100 milliseconds per each 10 seconds
proxy.rule(toxy.rules.timeThreshold(100))
// Enable poisoning during 1 second every minute
proxy.rule(toxy.rules.timeThreshold({ duration: 1000, period: 1000 * 60 }))
```

#### Method

<table>
<tr>
<td><b>Name</b></td><td>method</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>incoming / outgoing</td>
</tr>
</table>

Filters by HTTP method.

**Arguments**:

- **method** `string|array` - Method or methods to filter.

```js
var method = toxy.rules.method(['GET', 'POST'])
toxy.rule(method)
```

#### Content Type

Filters by content type header. It should be present

**Arguments**:

- **value** `string|regexp` - Header value to match.

```js
var rule = toxy.rules.contentType('application/json')
toxy.rule(rule)
```

#### Headers

<table>
<tr>
<td><b>Name</b></td><td>headers</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>incoming / outgoing</td>
</tr>
</table>

Filter by request headers.

**Arguments**:

- **headers** `object` - Headers to match by key-value pair. `value` can be a string, regexp, `boolean` or `function(headerValue, headerName) => boolean`

```js
var matchHeaders = {
  'content-type': /^application/\json/i,
  'server': true, // meaning it should be present,
  'accept': function (value, key) {
    return value.indexOf('text') !== -1
  }
}

var rule = toxy.rules.headers(matchHeaders)
toxy.rule(rule)
```

#### Response headers

<table>
<tr>
<td><b>Name</b></td><td>responseHeaders</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>outgoing</td>
</tr>
</table>

Filter by response headers from target server. Same as `headers` rule, but evaluating the outgoing request.

**Arguments**:

- **headers** `object` - Headers to match by key-value pair. `value` can be a `string`, `regexp`, `boolean` or `function(headerValue, headerName) => boolean`

```js
var matchHeaders = {
  'content-type': /^application/\json/i,
  'server': true, // meaning it should be present,
  'accept': function (value, key) {
    return value.indexOf('text') !== -1
  }
}

var rule = toxy.rules.responseHeaders(matchHeaders)
toxy.rule(rule)
```

#### Body

<table>
<tr>
<td><b>Name</b></td><td>body</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>incoming / outgoing</td>
</tr>
</table>

Match incoming body payload by a given `string`, `regexp` or custom filter `function`.

This rule is pretty simple, so for complex body matching (e.g: validating against a JSON schema)
you should probably write your own rule.

**Arguments**:

- **match** `string|regexp|function` - Body content to match
- **limit** `string` - Optional. Body limit in human size. E.g: `5mb`
- **encoding** `string` - Body encoding. Default to `utf8`
- **length** `number` - Body length. Default taken from `Content-Length` header

```js
var rule = toxy.rules.body('"hello":"world"')
toxy.rule(rule)

// Or using a filter function returning a boolean
var rule = toxy.rules.body(function contains(body) {
  return body.indexOf('hello') !== -1
})
toxy.rule(rule)
```

#### Response body

<table>
<tr>
<td><b>Name</b></td><td>responseBody</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>outgoing</td>
</tr>
</table>

Match outgoing body payload by a given `string`, `regexp` or custom filter `function`.

**Arguments**:

- **match** `string|regexp|function` - Body content to match
- **encoding** `string` - Body encoding. Default to `utf8`
- **length** `number` - Body length. Default taken from `Content-Length` header

```js
var rule = toxy.rules.responseBody('"hello":"world"')
toxy.rule(rule)

// Or using a filter function returning a boolean
var rule = toxy.rules.responseBody(function contains(body) {
  return body.indexOf('hello') !== -1
})
toxy.rule(rule)
```

#### Response status

<table>
<tr>
<td><b>Name</b></td><td>responseStatus</td>
</tr>
<tr>
<td><b>Poison Phase</b></td><td>outgoing</td>
</tr>
</table>

Evaluates the response status from the target server.
Only applicable to outgoing poisons.

**Arguments**:

- **range** `array` - Pair of status code range to match. Default `[200, 300]`.
- **lower** `number` - Compare status as `lower than` operation. Default to `null`.
- **higher** `number` - Compare status as `higher than` operation. Default to `null`.
- **value** `number` - Status code to match using a strict equality comparison. Default `null`.
- **include** `array` - Unordered list of status codes to match. Useful to specify custom status. Default `null`

```js
// Strict evaluation of the status code
toxy.rule(toxy.rules.responseBody(200))
// Using a range of valid status
toxy.rule(toxy.rules.responseBody([200, 204]))
// Using relational comparison
toxy.rule(toxy.rules.responseBody({ higher: 199, lower: 400 }))
// Custom unordered status code to match
toxy.rule(toxy.rules.responseBody({ include: [200, 204, 400, 404] }))
```

### Third-party rules

List of available third-party rules provided by the community. PR are welcome.

- [IP](https://github.com/h2non/toxy-ip) - Enable/disable poisons based on the client IP address (supports CIDR, subnets, ranges...).

### How to write rules

Rules are simple middleware functions that resolve asynchronously with a `boolean` value to determine if a given HTTP transaction should be ignored when poisoning.

Your rule must resolve with a `boolean` param calling the `next(err,
shouldIgnore)` function in the middleware, passing a `true` value if the rule has not matches and should not apply the poisoning, and therefore continuing with the next middleware stack.

Here's an example of a simple rule matching the HTTP method to determine if:
```js
var toxy = require('toxy')

function customMethodRule(matchMethod) {
  /**
   * We name the function since it's used by toxy to identify the rule to get/disable/remove it in the future
   */
  return function customMethodRule(req, res, next) {
    var shouldIgnore = req.method !== matchMethod
    next(null, shouldIgnore)
  }
}

var proxy = toxy()

// Register and enable the rule
proxy
  .get('/foo')
  .rule(customMethodRule('GET'))
  .poison(/* ... */)
```

You can optionally extend the build-in rules with your own rules:

```js
toxy.addRule(customMethodRule)

// Then you can use it as a built-in poison
proxy
  .get('/foo')
  .rules(toxy.rules.customMethodRule)
```

For featured real examples, take a look to the built-in rules [implementation](https://github.com/h2non/toxy/tree/master/lib/rules)

## Programmatic API

`toxy` API is completely built on top the [rocky API](https://github.com/h2non/rocky#programmatic-api). In other words, you can use any of the methods, features and middleware layer natively provided by `rocky`.

### toxy([ options ])

Create a new `toxy` proxy.

For supported `options`, please see rocky [documentation](https://github.com/h2non/rocky#configuration)

```js
var toxy = require('toxy')

toxy({ forward: 'http://server.net', timeout: 30000 })

toxy
  .get('/foo')
  .poison(toxy.poisons.latency(1000))
  .withRule(toxy.rules.contentType('json'))
  .forward('http://foo.server')

toxy
  .post('/bar')
  .poison(toxy.poisons.bandwidth({ bps: 1024 }))
  .withRule(toxy.rules.probability(50))
  .forward('http://bar.server')

toxy
  .post('/boo')
  .outgoingPoison(toxy.poisons.bandwidth({ bps: 1024 }))
  .withRule(toxy.rules.method('GET'))
  .forward('http://boo.server')

toxy.all('/*')

toxy.listen(3000)
```

#### toxy#get(path, [ middleware... ])
Return: `ToxyRoute`

Register a new route for `GET` method.

#### toxy#post(path, [ middleware... ])
Return: `ToxyRoute`

Register a new route for `POST` method.

#### toxy#put(path, [ middleware... ])
Return: `ToxyRoute`

Register a new route for `PUT` method.

#### toxy#patch(path, [ middleware... ])
Return: `ToxyRoute`

#### toxy#delete(path, [ middleware... ])
Return: `ToxyRoute`

Register a new route for `DELETE` method.

#### toxy#head(path, [ middleware... ])
Return: `ToxyRoute`

Register a new route for `HEAD` method.

#### toxy#all(path, [ middleware... ])
Return: `ToxyRoute`

Register a new route for any method.

#### toxy#poisons `=>` Object

Exposes a map with the built-in poisons. Prototype alias to `toxy.poisons`

#### toxy#rules `=>` Object

Exposes a map with the built-in poisons. Prototype alias to `toxy.rules`

#### toxy#forward(url)

Define a URL to forward the incoming traffic received by the proxy.

#### toxy#balance(urls)

Forward to multiple servers balancing among them.

For more information, see the [rocky docs](https://github.com/h2non/rocky#programmatic-api)

#### toxy#replay(url)

Define a new replay server.
You can call this method multiple times to define multiple replay servers.

For more information, see the [rocky docs](https://github.com/h2non/rocky#programmatic-api)

#### toxy#use(middleware)

Plug in a custom middleware.

For more information, see the [rocky docs](https://github.com/h2non/rocky#middleware-layer).

#### toxy#useResponse(middleware)

Plug in a response outgoing traffic middleware.

For more information, see the [rocky docs](https://github.com/h2non/rocky#middleware-layer).

#### toxy#useReplay(middleware)

Plug in a replay traffic middleware.

For more information, see the [rocky docs](https://github.com/h2non/rocky#middleware-layer)

#### toxy#requestBody(middleware)

Intercept incoming request body. Useful to modify it on the fly.

For more information, see the [rocky docs](https://github.com/h2non/rocky#programmatic-api)

#### toxy#responseBody(middleware)

Intercept outgoing response body. Useful to modify it on the fly.

For more information, see the [rocky docs](https://github.com/h2non/rocky#programmatic-api)

#### toxy#middleware()

Return a standard middleware to use with connect/express.

#### toxy#host(host)

Overwrite the `Host` header with a custom value. Similar to `forwardHost` option.

#### toxy#redirect(url)

Redirect traffic to the given URL.

#### toxy#findRoute(routeIdOrPath, [ method ])

Find a route by ID or path and method.

#### toxy#listen(port)

Starts the built-in HTTP server, listening on a specific TCP port.

#### toxy#close([ callback ])

Closes the HTTP server.

#### toxy#poison(poison)
Alias: `usePoison`, `useIncomingPoison`

Register a new poison to infect [incoming](#poisoning-phases) traffic.

#### toxy#outgoingPoison(poison)
Alias: `useOutgoingPoison`, `responsePoison`

Register a new poison to infect [outgoing](#poisoning-phases) traffic.

#### toxy#rule(rule)
Alias: `useRule`

Register a new rule.

#### toxy#withRule(rule)
Aliases: `ifRule`, `whenRule`, `poisonRule`, `poisonFilter`

Apply a new rule for the latest registered poison.

#### toxy#enable(poison)

Enable a poison by name identifier

#### toxy#disable(poison)

Disable a poison by name identifier

#### toxy#remove(poison)
Return: `boolean`

Remove an incoming traffic poison by name identifier or object reference.

#### toxy#removeOutgoing(poison)
Return: `boolean`

Remove an outgoing traffic poison by name identifier or object reference.

#### toxy#isEnabled(poison)
Return: `boolean`

Checks if a poison is enabled by name identifier.

#### toxy#disableAll()
Alias: `disablePoisons`

Disable all the registered poisons.

#### toxy#getPoison(name)
Return: `Directive|null`

Searches and retrieves a registered poison in the stack by name identifier.

#### toxy#getIncomingPoison(name)
Return: `Directive|null`

Searches and retrieves a registered `incoming` poison in the stack by name identifier.

#### toxy#getOutgoingPoison(name)
Return: `Directive|null`

Searches and retrieves a registered `outgoing` poison in the stack by name identifier.

#### toxy#getPoisons()
Return: `array<Directive>`

Return an array of registered poisons.

#### toxy#getIncomingPoisons()
Return: `array<Directive>`

Return an array of registered `incoming` poisons.

#### toxy#getOutgoingPoisons()
Return: `array<Directive>`

Return an array of registered `outgoing` poisons.

#### toxy#flush()
Alias: `flushPoisons`

Remove all the registered poisons for both incoming and outgoing traffic flows.

#### toxy#enableRule(rule)

Enable a rule by name identifier.

#### toxy#disableRule(rule)

Disable a rule by name identifier.

#### toxy#removeRule(rule)
Return: `boolean`

Remove a rule by name identifier.

#### toxy#disableRules()

Disable all the registered rules.

#### toxy#isRuleEnabled(rule)
Return: `boolean`

Checks if the given rule is enabled by name identifier.

#### toxy#getRule(rule)
Return: `Directive|null`

Searches and retrieves a registered rule in the stack by name identifier.

#### toxy#getRules()
Return: `array<Directive>`

Returns and array with the registered rules wrapped as `Directive`.

#### toxy#flushRules()

Remove all the rules.

### toxy.addPoison(name, fn)

Extend built-in poisons.

### toxy.addRule(name, fn)

Extend built-in rules.

### toxy.poisons `=>` Object

Exposes a map with the built-in poisons.

### toxy.rules `=>` Object

Exposes a map with the built-in rules.

### toxy.VERSION `=>` String

Current toxy semantic version.

### ToxyRoute

`ToxyRoute` exposes the same interface as `Toxy` global interface, it just adds some route level [additional methods](https://github.com/h2non/rocky#routepath).

Further actions you perform against the `ToxyRoute` API will only be applicable at route-level (nested). In other words: you already know the API.

This example will probably clarify possible doubts:
```js
var toxy = require('toxy')
var proxy = toxy()

// Now using the global API
proxy
  .forward('http://server.net')
  .poison(toxy.poisons.bandwidth({ bps: 1024 }))
  .rule(toxy.rules.method('GET'))

// Now create a route
var route = proxy
  .get('/foo')
  .toPath('/bar') // Route-level API method
  .host('server.net') // Route-level API method
  .forward('http://new.server.net')

// Now using the ToxyRoute interface
route
  .poison(toxy.poisons.bandwidth({ bps: 512 }))
  .rule(toxy.rules.contentType('json'))
```

### Directive(middlewareFn)

A convenient wrapper internally used for poisons and rules.

Normally you don't need to know this interface, but for hacking purposes or more low-level actions might be useful.

#### Directive#enable()
Return: `boolean`

#### Directive#disable()
Return: `boolean`

#### Directive#isEnabled()
Return: `boolean`

#### Directive#rule(rule)
Alias: `filter`

#### Directive#handler()
Return: `function(req, res, next)`

## HTTP API

The `toxy` HTTP API follows the [JSON API](http://jsonapi.org) conventions, including resource based hypermedia linking.

### Usage

For a featured use case, see the [admin server](examples/admin.js) example.

```js
const toxy = require('toxy')

// Create the toxy admin server
var admin = toxy.admin({ cors: true })
admin.listen(9000)

// Create the toxy proxy
var proxy = toxy()
proxy.listen(3000)

// Add the toxy instance to be managed by the admin server
admin.manage(proxy)

// Then configure the proxy
proxy
  .forward('http://my.target.net')

proxy
  .get('/slow')
  .poison(toxy.poisons.bandwidth({ bps: 1024 }))

// Handle the rest of the traffic
proxy
  .all('/*')
  .poison(toxy.poisons.bandwidth({ bps: 1024 * 5 }))

console.log('toxy proxy listening on port:', 3000)
console.log('toxy admin server listening on port:', 9000)
```

For more details about the admin programmatic API, see [below](#programmatic-api-1).

### Authorization

The HTTP API can be protected to unauthorized clients.
Authorized clients must define the API key token via `API-Key` or `Authorization` HTTP headers.

To enable it, you should simple pass the following options to `toxy` admin server:

```js
const toxy = require('toxy')

const opts = { apiKey: 's3cr3t' }
var admin = toxy.admin(opts)

admin.listen(9000)
console.log('protected toxy admin server listening on port:', 9000)
```

### API

**Hierarchy**:

- **Servers** - Managed `toxy` instances
  - **Rules** - Globally applied rules
  - **Poisons** - Globally applied poisons
    - **Rules** - Poison-specific rules
  - **Routes** - List of configured routes
    - **Route** - Object for each specific route
      - **Rules** - Route-level registered rules
      - **Poisons** - Route-level registered poisons
        - **Rules** - Route-level poison-specific rules

#### GET /

### Servers

#### GET /servers

#### GET /servers/:id

### Rules

#### GET /servers/:id/rules

#### POST /servers/:id/rules
Accepts: `application/json`

Example payload:
```js
{
  "name": "method",
  "options": "GET"
}
```

#### DELETE /servers/:id/rules

#### GET /servers/:id/rules/:id

#### DELETE /servers/:id/rules/:id

### Poisons

#### GET /servers/:id/poison

#### POST /servers/:id/poisons
Accepts: `application/json`

Example payload:
```js
{
  "name": "latency",
  "phase": "outgoing",
  "options": { "jitter": 1000 }
}
```

#### DELETE /servers/:id/poisons

#### GET /servers/:id/poisons/:id

#### DELETE /servers/:id/poisons/:id

#### GET /servers/:id/poisons/:id/rules

#### POST /servers/:id/poisons/:id/rules
Accepts: `application/json`

Example payload:
```js
{
  "name": "method",
  "options": "GET"
}
```

#### DELETE /servers/:id/poisons/:id/rules

#### GET /servers/:id/poisons/:id/rules/:id

#### DELETE /servers/:id/poisons/:id/rules/:id

### Routes

#### GET /servers/:id/routes

#### POST /servers/:id/routes
Accepts: `application/json`

Example payload:
```js
{
  "path": "/foo", // Required
  "method": "GET", // use ALL for all the methods
  "forward": "http://my.server", // Optional custom forward server URL
}
```

#### DELETE /servers/:id/routes

#### GET /servers/:id/routes/:id

#### DELETE /servers/:id/routes/:id

### Route rules

#### GET /servers/:id/routes/:id/rules

#### POST /servers/:id/routes/:id/rules
Accepts: `application/json`

Example payload:
```js
{
  "name": "method",
  "options": "GET"
}
```

#### DELETE /servers/:id/routes/:id/rules

#### GET /servers/:id/routes/:id/rules/:id

#### DELETE /servers/:id/routes/:id/rules/:id

### Route poisons

#### GET /servers/:id/routes/:id/poisons

#### POST /servers/:id/routes/:id/poisons
Accepts: `application/json`

Example payload:
```js
{
  "name": "latency",
  "phase": "outgoing",
  "options": { "jitter": 1000 }
}
```

#### DELETE /servers/:id/routes/:id/poisons

#### GET /servers/:id/routes/:id/poisons/:id

#### DELETE /servers/:id/routes/:id/poisons/:id

#### GET /servers/:id/routes/:id/poisons/:id/rules

#### POST /servers/:id/routes/:id/poisons/:id/rules

Accepts: `application/json`

Example payload:
```js
{
  "name": "method",
  "options": "GET"
}
```

#### DELETE /servers/:id/routes/:id/poisons/:id/rules

#### GET /servers/:id/routes/:id/poisons/:id/rules/:id

#### DELETE /servers/:id/routes/:id/poisons/:id/rules/:id

### Programmatic API

The built-in HTTP admin server also provides a simple interface open to extensibility and hacking purposes.
For instance, you can plug in additional middleware to the admin server, or register new routes.

#### toxy.admin([ opts ])
Returns: `Admin`

**Supported options**:

- **apiKey** `string` - Optional API key to protect the server
- **port** `number` - Optional. TCP port to listen
- **cors** `boolean` - Enable CORS for web browser access
- **middleware** `array<function>` - Plug in additional middleware
- **ssl** `object` - Node.js HTTPS server [TLS options](https://nodejs.org/api/tls.html#tls_tls_createserver_options_secureconnectionlistener).

##### Admin#listen([ port, host ])

Start listening on the network.

##### Admin#manage(toxy)

Manage a `toxy` server instance.

##### Admin#find(toxy)

Find a toxy instance. Accepts toxy server ID or toxy instance.

##### Admin#remove(toxy)

Stop managing a toxy instance.

##### Admin#use(...middleware)

Register a middleware.

##### Admin#param(...middleware)

Register a param middleware.

##### Admin#get(path, [ ...middleware ])

Register a GET route.

##### Admin#post(path, [ ...middleware ])

Register a POST route.

##### Admin#put(path, [ ...middleware ])

Register a PUT route.

##### Admin#delete(path, [ ...middleware ])

Register a DELETE route.

##### Admin#patch(path, [ ...middleware ])

Register a PATCH route.

##### Admin#all(path, [ ...middleware ])

Register a route accepting any HTTP method.

##### Admin#middleware(req, res, next)

Middleware to plug in with connect/express.

##### Admin#close(cb)

Stop the server.

## License

MIT - Tomas Aparicio

[![views](https://sourcegraph.com/api/repos/github.com/h2non/toxy/.counters/views.svg)](https://sourcegraph.com/github.com/h2non/toxy)
