6.2. DNS Push Notification SUBSCRIBE

6.2. DNS Push Notification SUBSCRIBE

After connecting, and requesting a longer idle timeout and/or keepalive interval if necessary, a DNS Push Notification client then indicates its desire to receive DNS Push Notifications for a given domain name by sending a SUBSCRIBE request to the server. A SUBSCRIBE request is encoded in a DSO message [RFC8490]. This specification defines a DSO Primary TLV for DNS Push Notification SUBSCRIBE Requests (DSO Type Code 0x0040).

DSO messages with the SUBSCRIBE TLV as the Primary TLV are permitted in TLS early data, provided that the precautions described in Section 7.3 are followed.

The entity that initiates a SUBSCRIBE request is by definition the client. A server MUST NOT send a SUBSCRIBE request over an existing session from a client. If a server does send a SUBSCRIBE request over a DSO session initiated by a client, this is a fatal error and the client MUST forcibly abort the connection immediately.

Each SUBSCRIBE request generates exactly one SUBSCRIBE response from the server. The entity that initiates a SUBSCRIBE response is by definition the server. A client MUST NOT send a SUBSCRIBE response. If a client does send a SUBSCRIBE response, this is a fatal error and the server MUST forcibly abort the connection immediately.