Add jamulusserver/privateChatMessage RPC method for sending messages to single channels (#3731)

* add jamulusserver/privateChatMessage RPC method for sending messages to single channels

* Check for invalid channel ID before sending private chat message and send corresponding response

* Added sanity checks for private chat message string

* update comment

* Apply suggestions from code review

Co-authored-by: Peter L Jones <pljones@users.noreply.github.com>

---------

Co-authored-by: Peter L Jones <pljones@users.noreply.github.com>

Author: dingodoppelt

docs/JSON-RPC.md

@@ -344,7 +344,7 @@ Results:
 
 ### jamulusserver/broadcastChatMessage
 
-Sends a message (as the server) to all connected clients. This can be used to broadcast messages from external sources (e.g. scripts or  monitoring tools).
+Sends a message (as the server) to all connected clients. This can be used to broadcast messages from external sources (e.g. scripts or monitoring tools).
 
 Parameters:
 
@@ -430,6 +430,24 @@ Results:
 | result.registrationStatus | string | The server registration status as string (see ESvrRegStatus and SerializeRegistrationStatus). |
 
 
+### jamulusserver/privateChatMessage
+
+Sends a chat message to a single connected client.
+
+Parameters:
+
+| Name | Type | Description |
+| --- | --- | --- |
+| params.chatMessage | string | The chat message text. |
+| params.id | number | The client's channel id. |
+
+Results:
+
+| Name | Type | Description |
+| --- | --- | --- |
+| result | string | "ok" or "error" if bad arguments. |
+
+
 ### jamulusserver/restartRecording
 
 Restarts the recording into a new directory.

src/server.cpp

@@ -1379,13 +1379,15 @@ void CServer::SendChatTextToAllConChannels ( const int iSendingChanID, const QSt
     emit sentChatMessage ( iSendingChanID, strChatText );
 }
 
-void CServer::SendChatTextToConChannel ( const int iCurChanID, const QString& strChatText )
+bool CServer::SendChatTextToConChannel ( const int iCurChanID, const QString& strChatText )
 {
-    if ( MathUtils::InRange<int> ( iCurChanID, 0, iMaxNumChannels - 1 ) && vecChannels[iCurChanID].IsConnected() )
+    if ( !MathUtils::InRange<int> ( iCurChanID, 0, iMaxNumChannels - 1 ) || !vecChannels[iCurChanID].IsConnected() )
     {
-        // send message
-        vecChannels[iCurChanID].CreateChatTextMes ( strChatText );
+        return false;
     }
+    // send message
+    vecChannels[iCurChanID].CreateChatTextMes ( strChatText );
+    return true;
 }
 
 void CServer::CreateAndSendRecorderStateForAllConChannels()

src/server.h

@@ -192,7 +192,7 @@ class CServer : public QObject, public CServerSlots<MAX_NUM_CHANNELS>
     bool IsDelayPanningEnabled() { return bDelayPan; }
 
     void SendChatTextToAllConChannels ( const int iSendingChanID, const QString& strChatText );
-    void SendChatTextToConChannel ( const int iCurChanID, const QString& strChatText );
+    bool SendChatTextToConChannel ( const int iCurChanID, const QString& strChatText );
 
 protected:
     // access functions for actual channels

src/serverrpc.cpp

@@ -113,6 +113,30 @@ CServerRpc::CServerRpc ( CServer* pServer, CRpcServer* pRpcServer, QObject* pare
         response["result"] = "ok";
     } );
 
+    /// @rpc_method jamulusserver/privateChatMessage
+    /// @brief Sends a chat message to a single connected client.
+    /// @param {string} params.chatMessage - The chat message text.
+    /// @param {number} params.id - The client's channel id.
+    /// @result {string} result - "ok" or "error" if bad arguments.
+    pRpcServer->HandleMethod ( "jamulusserver/privateChatMessage", [=] ( const QJsonObject& params, QJsonObject& response ) {
+        auto          jsonChatMessage = params["chatMessage"];
+        const int     id              = params["id"].toInt ( INVALID_CLIENT_ID );
+        const QString chatMessage     = jsonChatMessage.toString();
+        if ( chatMessage.isEmpty() || chatMessage.size() > MAX_LEN_CHAT_TEXT )
+        {
+            response["error"] =
+                CRpcServer::CreateJsonRpcError ( CRpcServer::iErrInvalidParams, "Invalid params: chatMessage is not a string or malformed" );
+            return;
+        }
+
+        if ( !pServer->SendChatTextToConChannel ( id, chatMessage ) )
+        {
+            response["error"] = "invalid channel ID";
+            return;
+        }
+        response["result"] = "ok";
+    } );
+
     /// @rpc_method jamulusserver/getRecorderStatus
     /// @brief Returns the recorder state.
     /// @param {object} params - No parameters (empty object).