# AdmissionWebhooks

## Overview

AdmissionWebhooks are HTTP callbacks that query the control server to control publishing and playback admission requests.

![](<../https://raw.githubusercontent.com/AirenSoft/OvenMediaEngine/v0.18.0/docs/.gitbook/assets/image (33).png>)

Users can use the AdmissionWebhook for a variety of purposes, including customer authentication, tracking published streams, hide app/stream names, logging and more.

## Configuration

AdmissionWebhooks can be set up on VirtualHost, as shown below.

```markup
<VirtualHost>
	<AdmissionWebhooks>
		<ControlServerUrl>https://192.168.0.161:9595/v1/admission</ControlServerUrl>
		<SecretKey>1234</SecretKey>
		<Timeout>3000</Timeout>
		<Enables>
			<Providers>rtmp,webrtc,srt</Providers>
			<Publishers>webrtc,llhls,thumbnail,srt</Publishers>
		</Enables>
	</AdmissionWebhooks>
</VirtualHost>
```

| Key              | Description                                                                                                                                      |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------ |
| ControlServerUrl | The HTTP Server to receive the query. HTTP and HTTPS are available.                                                                              |
| SecretKey        | <p>The secret key used when encrypting with HMAC-SHA1</p><p>For more information, see <a href="admission-webhooks.md#security">Security</a>.</p> |
| Timeout          | Time to wait for a response after request (in milliseconds)                                                                                      |
| Enables          | Enable Providers and Publishers to use AdmissionWebhooks                                                                                         |

## Request

### Format

AdmissionWebhooks send HTTP/1.1 request message to the configured user's control server when an encoder requests publishing or a player requests playback. The request message format is as follows.

```http
POST /configured/target/url/ HTTP/1.1
Content-Length: 325
Content-Type: application/json
Accept: application/json
X-OME-Signature: f871jd991jj1929jsjd91pqa0amm1
{
  "client": 
  {
    "address": "211.233.58.86",
    "port": 29291,
    "real_ip": "192.0.2.43",
    "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36"
  },
  "request":
  {
    "direction": "incoming | outgoing",
    "protocol": "webrtc | rtmp | srt | llhls | thumbnail",
    "status": "opening | closing",
    "url": "scheme://host[:port]/app/stream/file?query=value&query2=value2",
    "new_url": "scheme://host[:port]/app/new_stream/file?query=value&query2=value2",
    "time": "2021-05-12T13:45:00.000Z"
  }
}
```

The message is sent in POST method and the payload is in application/json format. X-OME-Signature is a base64 url safe encoded value obtained by encrypting the payload with HMAC-SHA1 so that the ControlServer can validate this message. See the [Security ](admission-webhooks.md#security)section for more information on X-OME-Signature.

Here is a detailed explanation of each element of Json payload:

<table><thead><tr><th width="138">Element</th><th width="162">Sub-Element</th><th>Description</th></tr></thead><tbody><tr><td>client</td><td></td><td>Information of the client who requested the connection.</td></tr><tr><td></td><td>address</td><td>IP address of the client connected to the server</td></tr><tr><td></td><td>port</td><td>Port number of the client connected to the server</td></tr><tr><td></td><td>real_ip</td><td>IP address of the client forwarded by the proxy server</td></tr><tr><td></td><td>user_agent<br>(optional)</td><td>Client's User_Agent</td></tr><tr><td>request</td><td></td><td>Information about the client's request</td></tr><tr><td></td><td>direction</td><td><p>incoming : A client requests to publish a stream</p><p>outgoing : A client requests to play a stream</p></td></tr><tr><td></td><td>protocol</td><td>webrtc, srt, rtmp, llhls, thumbnail</td></tr><tr><td></td><td>status</td><td><p>opening : A client requests to open a stream</p><p>closing : A client closed the stream</p></td></tr><tr><td></td><td>url</td><td>url requested by the client</td></tr><tr><td></td><td>new_url<br>(optional)</td><td>url redirected from user's control server (status "closing" only)</td></tr><tr><td></td><td>time</td><td>time requested by the client (ISO8601 format)</td></tr></tbody></table>

{% hint style="info" %}
OME searches for and sets the values ​​in real\_ip in the following order:

1. The value of the X-REAL-IP header&#x20;
2. The value of the first item of X-FORWARDED-FOR&#x20;
3. The IP of the client that is actually connected
{% endhint %}

### Security

The control server may need to validate incoming http requests for security reasons. To do this, the AdmissionWebhooks module puts the `X-OME-Signature` value in the HTTP request header. `X-OME-Signature` is a base64 url safe encoded value obtained by encrypting the payload of an HTTP request with the HMAC-SHA1 algorithm using the secret key set in `<AdmissionWebhooks><SecretKey>` of the configuration.

### Conditions that triggers the request

As shown below, the trigger condition of request is different for each protocol.

| Protocol | Condition                                                                                                                |
| -------- | ------------------------------------------------------------------------------------------------------------------------ |
| WebRTC   | When a client requests Offer SDP                                                                                         |
| RTMP     | When a client sends a publish message                                                                                    |
| SRT      | When a client send a [streamid](https://airensoft.gitbook.io/ovenmediaengine/live-source/srt-beta#encoders-and-streamid) |
| LLHLS    | When a client requests a playlist (llhls.m3u8)                                                                           |

## Response for closing status

The engine in the closing state does not need any parameter in response. To the query just answer with empty json object.

```http
HTTP/1.1 200 OK
Content-Length: 5
Content-Type: application/json
Connection: Closed
{
}
```

## Response for opening status

### Format

ControlServer must respond with the following Json format. In particular, the `"allowed"` element is required.

```http
HTTP/1.1 200 OK
Content-Length: 102
Content-Type: application/json
Connection: Closed
{
  "allowed": true,
  "new_url": "scheme://host[:port]/app/stream/file?query=value&query2=value2",
  "lifetime": milliseconds,
  "reason": "authorized"
}
```

| Element                | Description                                                                                                                                                                                                                               |
| ---------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| allowed **(required)** | <p>true or false</p><p>Allows or rejects the client's request.</p>                                                                                                                                                                        |
| new\_url (optional)    | Redirects the client to a new url. However, the `scheme`, `port`, and `file` cannot be different from the request. Only host, app, and stream can be changed. The host can only be changed to another virtual host on the same server.    |
| lifetime (optional)    | <p>The amount of time (in milliseconds) that a client can maintain a connection (Publishing or Playback)</p><ul><li>0 means infinity</li></ul><p>HTTP based streaming (HLS) does not keep a connection, so this value does not apply.</p> |
| reason (optional)      | If allowed is false, it will be output to the log.                                                                                                                                                                                        |

### User authentication and control

`new_url` redirects the original request to another app/stream. This can be used to hide the actual app/stream name from the user or to authenticate the user by inserting additional information instead of the app/stream name.

For example, you can issue a WebRTC streaming URL by inserting the user ID as follows: `ws://domain.com:3333/user_id` It will be more effective if you issue a URl with the encrypted value that contains the user ID, url expiration time, and other information.

After the Control Server checks whether the user is authorized to play using `user_id`, and responds with `ws://domain.com:3333/app/sport-3` to `new_url`, the user can play app/sport-3.

If the user has only one hour of playback rights, the Control Server responds by putting 3600000 in the `lifetime`.
