SignedPolicy is a module that limits the user's privileges and time. For example, operators can distribute RTMP URLs that can be accessed for 60 seconds to authorized users, and limit RTMP transmission to 1 hour. The provided URL will be destroyed after 60 seconds, and transmission will automatically stop after 1 hour. Users who are provided with a SignedPolicy URL cannot access resources other than the provided URL. This is because the SignedPolicy URL is authenticated.
SignedPolicy URL consists of the query string of the streaming URL with Policy and Signature as shown below. If SignedPolicy is enabled in the configuration of OvenMediaEngine, access to URLs with no signature or invalid signature is not allowed. Signature uses HMAC-SHA1 to authenticate all URLs except signature.
Policy is in json format and provides the following properties.
| Key | Value | Description |
|---|---|---|
url_expire means the time the URL is valid, so if you connect before the URL expires, you can continue to use it, and sessions that have already been connected will not be deleted even if the time expires. However, stream_expire forcibly terminates the session when the time expires even if it is already playing.
Signature is generated by HMAC-SHA1 encoding all URLs except signature query string. The generated Signature is encoded using Base64URL and included as a query string of the existing URL.
The URL entered into HMAC to generate the Signature must include :port.
When creating a signature, you cannot omit the default port such as http port 80, https port 443, or rtmp port 1935. This is because when OvenMediaEngine creates a signature for checking the signature, it is created by putting the port value.
When using SignedPolicy with SRT providers, only use the streamid portion of the URL, e.g. srt://myserver:9999?streamid=srt://myserver:9999/app/stream?policy=abc123
To enable SignedPolicy, you need to add the following <SignedPolicy> setting in Server.xml under <VirtualHost>.
We provide a script that can easily generate SignedPolicy URL. The script can be found in the path below.
Here's how to use this script:
For example, you can use it like this:
We hope to provide SignedPolicy URL Generator Library in various languages. If you have created the SignedPolicy URL Generator Library in another language, please send a Pull Request to our GITHUB. Thank you for your open source contributions.
In order to include the policy in the URL, it must be encoded with Base64URL.
Policy encoded with Base64URL is added as a query string to the existing streaming URL. (The query string key is set in Server.xml.)
Signature hashes the entire URL including the policy in HMAC (SHA-1) method, encodes it as Base64URL, and includes it in the query string.
Create a hash using the secret key (1kU^b6 in the example) and the URL above using HMAC-SHA1.
If you include it as a signature query string (query string key is set in Server.xml), the following SignedPolicy URL is finally generated.
Generate SignedPolicy URL with the script.
Separate the URL based on "app" as shown in the example below and enter all the parts under the stream in the Stream Key.
AdmissionWebhooks are HTTP callbacks that query the control server to control publishing and playback admission requests.
Users can use the AdmissionWebhook for a variety of purposes, including customer authentication, tracking published streams, hide app/stream names, logging and more.
AdmissionWebhooks can be set up on VirtualHost, as shown below.
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.
Here is a detailed explanation of each element of Json payload:
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.
As shown below, the trigger condition of request is different for each protocol.
The engine in the closing state does not need any parameter in response. To the query just answer with empty json object.
ControlServer must respond with the following Json format. In particular, the "allowed" element is required.
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.
| Key | Description |
|---|---|
| Key | Description |
|---|
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 section for more information on X-OME-Signature.
| Element | Sub-Element | Description |
|---|
| Protocol | Condition |
|---|
| Element | Description |
|---|
url_expire
(Required)
<Number> Milliseconds since unix epoch
The time the URL expires Reject on request after the expiration
url_activate
(Optional)
<Number> Milliseconds since unix epoch
The time the URL activates Reject on request before activation
stream_expire
(Optional)
<Number> Milliseconds since unix epoch
The time the Stream expires Transmission and playback stop when the time expires
allow_ip
(Optional)
<String> IPv4 CIDR
Allowed IP address range, 192.168.0.0/24
PolicyQueryKeyName
The query string key name in the URL pointing to the policy value
SignatureQueryKeyName
The query string key name in the URL pointing to the signature value
SecretKey
The secret key used when encoding with HMAC-SHA1
Enables
List of providers and publishers to enable SignedPolicy. Currently, SignedPolicy supports rtmp among providers, and among publishers, WebRTC, LLHLS, Thumbnail are supported.
client | Information of the client who requested the connection. |
address | Client's IP address |
port | Client's Port number |
user_agent (optional) | Client's User_Agent |
request | Information about the client's request |
direction | incoming : A client requests to publish a stream outgoing : A client requests to play a stream |
protocol | webrtc, srt, rtmp, llhls, thumbnail |
status | opening : A client requests to open a stream closing : A client closed the stream |
url | url requested by the client |
new_url (optional) | url redirected from user's control server (status "closing" only) |
time | time requested by the client (ISO8601 format) |
allowed (required) | true or false Allows or rejects the client's request. |
new_url (optional) | Redirects the client to a new url. However, the |
lifetime (optional) | The amount of time (in milliseconds) that a client can maintain a connection (Publishing or Playback)
HTTP based streaming (HLS, DASH, LLDASH) does not keep a connection, so this value does not apply. |
reason (optional) | If allowed is false, it will be output to the log. |
ControlServerUrl | The HTTP Server to receive the query. HTTP and HTTPS are available. |
SecretKey | The secret key used when encrypting with HMAC-SHA1 |
Timeout | Time to wait for a response after request (in milliseconds) |
Enables | Enable Providers and Publishers to use AdmissionWebhooks |
WebRTC | When a client requests Offer SDP |
RTMP | When a client sends a publish message |
SRT |
LLHLS | When a client requests a playlist (llhls.m3u8) |
For more information, see .
When a client send a
