feat(rumqttd): unsubscribe method in local link (#894)

rumqttd/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - Assign random identifier to clients connecting with empty client id.
+- `Unsubscribe` with `local::LinkTx`.
 
 ### Changed
 - Public re-export `Strategy` for shared subscriptions

rumqttd/src/link/local.rs

@@ -1,5 +1,6 @@
 use crate::protocol::{
     Filter, LastWill, LastWillProperties, Packet, Publish, QoS, RetainForwardRule, Subscribe,
+    Unsubscribe,
 };
 use crate::router::Ack;
 use crate::router::{
@@ -281,6 +282,28 @@ impl LinkTx {
         Ok(len)
     }
 
+    /// Sends a MQTT Unsubscribe to the eventloop
+    pub fn unsubscribe<S: Into<String>>(&mut self, filter: S) -> Result<usize, LinkError> {
+        let unsubscribe = Unsubscribe {
+            pkid: 0,
+            filters: vec![filter.into()],
+        };
+
+        let len = self.push(Packet::Unsubscribe(unsubscribe, None))?;
+        Ok(len)
+    }
+
+    /// Sends a MQTT Unsubscribe to the eventloop
+    pub fn try_unsubscribe<S: Into<String>>(&mut self, filter: S) -> Result<usize, LinkError> {
+        let unsubscribe = Unsubscribe {
+            pkid: 0,
+            filters: vec![filter.into()],
+        };
+
+        let len = self.try_push(Packet::Unsubscribe(unsubscribe, None))?;
+        Ok(len)
+    }
+
     /// Request to get device shadow
     pub fn shadow<S: Into<String>>(&mut self, filter: S) -> Result<(), LinkError> {
         let message = Event::Shadow(ShadowRequest {