verifying if user is member of conversation before joining

server/db/db.js

@@ -990,6 +990,28 @@ async function removeUserFromGroupById(conversation_id, user_id) {
   }
 }
 
+async function isConversationMember(user_id, conversation_id) {
+  const query = `
+    SELECT EXISTS (
+      SELECT 1 
+      FROM Memberships 
+      WHERE user_id = $1 
+      AND conversation_id = $2
+    ) AS is_member;
+  `;
+
+  try {
+    const result = await client.query(query, [user_id, conversation_id]);
+    return result.rows[0].is_member;
+  } catch (e) {
+    console.error(
+      `Failed to verify membership for user_id: ${user_id} in conversation_id: ${conversation_id}`,
+      e,
+    );
+    return false;
+  }
+}
+
 module.exports = {
   client,
   insertUser,
@@ -1010,4 +1032,5 @@ module.exports = {
   deleteMessage,
   getMembers,
   removeUserFromGroupById,
+  isConversationMember,
 };

server/socket/socket.js

@@ -4,6 +4,7 @@ const {
   deleteContact,
   deleteMessage,
   removeUserFromGroupById,
+  isConversationMember,
 } = require("../db/db");
 const { isValidUsername } = require("../utils/filter");
 const { verifyJwtToken } = require("../auth/jwt");
@@ -76,9 +77,24 @@ function initializeSocket(io) {
       console.error("(socket) Failed to get user conversations");
     }
 
-    socket.on("join room", (msg) => {
-      console.log("Join room for: ", username, "room: ", msg);
-      socket.join(msg);
+    socket.on("join room", async (conversation_id, callback) => {
+      const isMember = await isConversationMember(
+        socket.user_id,
+        conversation_id,
+      );
+      if (isMember) {
+        console.log("Join room for: ", username, "room: ", conversation_id);
+        socket.join(conversation_id);
+        return callback({
+          status: "ok",
+          message: "Successfully joined to conversation",
+        });
+      } else {
+        return callback({
+          status: "error",
+          message: "You are not member of this conversation",
+        });
+      }
     });
 
     socket.on("chat message", async (msg, callback) => {