Reverted hard requirement for gateway protocol presence (#1875)

common/client-libs/gateway-client/src/client.rs

@@ -408,18 +408,24 @@ impl GatewayClient {
     ) -> Result<(), GatewayClientError> {
         // right now there are no failure cases here, but this might change in the future
         match gateway_protocol {
-            Some(v) if v == PROTOCOL_VERSION => {
-                info!("the gateway is using exactly the same protocol version as we are. We're good to continue!");
+            None => {
+                warn!("the gateway we're connected to has not specified its protocol version. It's probably running version < 1.1.X, but that's still fine for now. It will become a hard error in 1.2.0");
+                // note: in +1.2.0 we will have to return a hard error here
                 Ok(())
             }
-            v => {
+            Some(v) if v != PROTOCOL_VERSION => {
                 let err = GatewayClientError::IncompatibleProtocol {
-                    gateway: v,
+                    gateway: Some(v),
                     current: PROTOCOL_VERSION,
                 };
                 error!("{err}");
                 Err(err)
             }
+
+            Some(_) => {
+                info!("the gateway is using exactly the same protocol version as we are. We're good to continue!");
+                Ok(())
+            }
         }
     }
 

gateway/src/node/client_handling/websocket/connection_handler/fresh.rs

@@ -348,18 +348,24 @@ where
     ) -> Result<(), InitialAuthenticationError> {
         // right now there are no failure cases here, but this might change in the future
         match client_protocol {
-            Some(v) if v == PROTOCOL_VERSION => {
-                info!("the client is using exactly the same protocol version as we are. We're good to continue!");
+            None => {
+                warn!("the client we're connected to has not specified its protocol version. It's probably running version < 1.1.X, but that's still fine for now. It will become a hard error in 1.2.0");
+                // note: in +1.2.0 we will have to return a hard error here
                 Ok(())
             }
-            v => {
+            Some(v) if v != PROTOCOL_VERSION => {
                 let err = InitialAuthenticationError::IncompatibleProtocol {
-                    client: v,
+                    client: Some(v),
                     current: PROTOCOL_VERSION,
                 };
                 error!("{err}");
                 Err(err)
             }
+
+            Some(_) => {
+                info!("the client is using exactly the same protocol version as we are. We're good to continue!");
+                Ok(())
+            }
         }
     }