Based on https://github.com/waku-org/pm/issues/93 this new version of lightpush protobuf protocol definition is proposed.

standards/core/lightpush.md

@@ -0,0 +1,88 @@
+---
+slug: 19
+title: 19/WAKU2-LIGHTPUSH
+name: Waku v2 Light Push
+status: draft
+editor: Zoltan Nagy <zoltan@status.im> 
+contributors: 
+  - Hanno Cornelius <hanno@status.im>
+  - Daniel Kaiser <danielkaiser@status.im>
+  - Oskar Thorén <oskarth@titanproxy.com>
+---
+
+previous version: `/vac/waku/lightpush/2.0.0-beta1` [19/WAKU2-LIGHTPUSH](https://rfc.vac.dev/waku/standards/core/19/lightpush)
+
+---
+**Protocol identifier**: `/vac/waku/lightpush/2.0.0-beta2`
+
+## Motivation and Goals
+
+Light nodes with short connection windows and limited bandwidth wish to publish messages into the Waku network.
+Additionally, there is sometimes a need for confirmation that a message has been received "by the network"
+(here, at least one node).
+
+`19/WAKU2-LIGHTPUSH` is a request/response protocol for this.
+
+## Payloads
+
+```protobuf
+syntax = "proto3";
+
+message LightPushRequest {
+    enum RequestType { // Future extension point
+        RELAY = 0;
+    }
+    
+    string request_id = 1;
+    RequestType kind = 10;  // default is RELAY, placeholder for future extensions
+    string pubsub_topic = 20;
+    WakuMessage message = 21;
+}
+
+message LightPushResponse {
+    enum Status {
+        SUCCESS = 0;
+        BAD_REQUEST = 400;
+        NO_PEERS_TO_RELAY = 404;
+        PAYLOAD_TOO_LARGE = 413;
+        UNSUPPORTED_TOPIC = 415;
+        TOO_MANY_REQUESTS = 429;
+        INTERNAL_SERVER_ERROR = 500;
+        SERVICE_UNAVAILABLE = 503;    
+    }
+
+    string request_id = 1;
+    Status status_code = 10;
+    optional string status_desc = 11;
+    uint32 relay_peer_count = 12;
+}
+```
+
+### Message Relaying
+
+Nodes that respond to `LightPushRequest` MUST either
+relay the encapsulated message via [11/WAKU2-RELAY](https://rfc.vac.dev/waku/standards/core/11/relay) protocol on the specified `pubsub_topic`,
+or forward the `LightPushRequest` via 19/LIGHTPUSH on a [WAKU2-DANDELION](https://github.com/waku-org/specs/blob/waku-RFC/standards/application/dandelion.md) stem.
+If they are unable to do so for some reason, they SHOULD return an error code in `LightPushResponse`.
+
+## Security Considerations
+
+Since this can introduce an amplification factor, it is RECOMMENDED for the node relaying to the rest of the network to take extra precautions.
+This can be done by rate limiting via [17/WAKU2-RLN-RELAY](https://rfc.vac.dev/waku/standards/core/17/rln-relay).
+
+Note that the above is currently not fully implemented.
+
+## Future work
+
+- Add support attaching RLN proof for the message requested to be relayed.
+- Add support for other request types.
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
+
+## References
+
+* [11/WAKU2-RELAY](https://rfc.vac.dev/waku/standards/core/11/relay)
+* [WAKU2-DANDELION](https://github.com/waku-org/specs/blob/waku-RFC/standards/application/dandelion.md)
+* [17/WAKU2-RLN-RELAY](https://rfc.vac.dev/waku/standards/core/17/rln-relay)