Add udp example and more api

examples/udp.lua

@@ -0,0 +1,82 @@
+meta = {
+    name = "UDP echo example",
+    description = "Opens UDP server on a random port and echoes sent messages, closes the server on 'gg'",
+    author = "Dregu",
+    unsafe = true
+}
+
+options = {
+    host = "127.0.0.1",
+    port = 0
+}
+
+function init()
+    deinit()
+
+    server = {
+        -- Save messages to queue instead of printing directly, cause that doesn't work from the server thread
+        queue = {},
+
+        -- Open server on an ephemeral random port, push messages to queue and echo back to sender
+        socket = udp_listen(options.host, options.port, function(msg)
+            msg = msg:gsub("%s*$", "")
+            table.insert(server.queue, msg)
+            if msg == "gg" then
+                return "bye!\n"
+            else
+                return "echo: " .. msg .. "\n"
+            end
+        end)
+    }
+
+    -- If port was opened successfully, start checking the message queue
+    if server.socket:open() then
+        print(F "Listening on {server.socket.port}, please send some UDP datagrams or 'gg' to close")
+        server.inter = set_global_interval(function()
+            for _, msg in pairs(server.queue) do
+                print(F "Received: {msg}")
+                if msg == "gg" then
+                    server.socket:close()
+                    clear_callback()
+                    print("Server is now closed, have a nice day")
+                end
+            end
+            server.queue = {}
+        end, 1)
+    else
+        print(F "Failed to open server: {server.socket:error()}")
+    end
+end
+
+function deinit()
+    if server then
+        server.socket:close()
+        if server.inter then clear_callback(server.inter) end
+        server = nil
+    end
+end
+
+set_callback(init, ON.LOAD)
+set_callback(init, ON.SCRIPT_ENABLE)
+set_callback(deinit, ON.SCRIPT_DISABLE)
+
+register_option_callback("x", nil, function(ctx)
+    options.host = ctx:win_input_text("Host", options.host)
+    options.port = ctx:win_input_int("Port", options.port)
+    if options.port < 0 then options.port = 0 end
+    if options.port > 65535 then options.port = 65535 end
+    if ctx:win_button("Start server") then init() end
+    ctx:win_inline()
+    if ctx:win_button("Stop server") then deinit() end
+    if server then
+        ctx:win_text(server.socket:error())
+    end
+    if server and server.socket:open() then
+        ctx:win_text(F "Listening on {server.socket.host}:{server.socket.port}\nTry sending something with udp_send:")
+        if ctx:win_button("Send 'Hello World!'") then udp_send(server.socket.host, server.socket.port, "Hello World!") end
+        ctx:win_inline()
+        if ctx:win_button("Send 'gg'") then udp_send(server.socket.host, server.socket.port, "gg") end
+    else
+        ctx:win_text("Stopped")
+    end
+end)

src/game_api/script/usertypes/socket_lua.cpp

@@ -13,10 +13,10 @@ namespace NSocket
 void register_usertypes(sol::state& lua)
 {
     lua.new_usertype<UdpServer>(
-        "UdpServer", sol::no_constructor, "close", &UdpServer::close, "open", &UdpServer::open, "error", &UdpServer::error);
+        "UdpServer", sol::no_constructor, "close", &UdpServer::close, "open", &UdpServer::open, "error", &UdpServer::error, "host", sol::readonly(&UdpServer::host), "port", sol::readonly(&UdpServer::port));
 
-    /// Start an UDP server on specified address and run callback when data arrives. Return a string from the callback to reply. Requires unsafe mode.
-    /// The server will be closed lazily by garbage collection once the handle is released, or immediately by calling close().
+    /// Start an UDP server on specified address and run callback when data arrives. Set port to 0 to use a random ephemeral port. Return a string from the callback to reply.
+    /// The server will be closed lazily by garbage collection once the handle is released, or immediately by calling close(). Requires unsafe mode.
     lua["udp_listen"] = [](std::string host, in_port_t port, sol::function cb)
     {
         return std::unique_ptr<UdpServer>{new UdpServer(std::move(host), std::move(port), make_safe_cb<UdpServer::SocketCb>(std::move(cb)))};

src/game_api/socket.cpp

@@ -78,6 +78,8 @@ UdpServer::UdpServer(std::string host_, in_port_t port_, std::function<SocketCb>
 {
     if (sock.bind(sockpp::inet_address(host, port)))
     {
+        const auto addr = (sockpp::inet_address)sock.address();
+        port = addr.port();
         is_opened = true;
         sock.set_non_blocking();
         kill_thr.test_and_set();

src/game_api/socket.hpp

@@ -19,7 +19,7 @@ class UdpServer
     /// Closes the server.
     void close();
 
-    /// Returns true if the port was opened successfully and hasn't been closed yet.
+    /// Returns true if the port was opened successfully and the server hasn't been closed yet.
     bool open();
 
     /// Returns a string explaining the last error, at least if open() returned false.