basic nodemcu stuff in lua/

lua/telnet.lua

@@ -0,0 +1,50 @@
+-- implement:
+-- quit/ctrl-d disconnect
+-- security?????
+-- multiclient?
+-- ssh????
+-- environment??????????
+
+
+-- a simple telnet server
+
+-- restart server if needed
+if telnet_srv ~= nil then
+    telnet_srv:close()
+end
+telnet_srv = net.createServer(net.TCP, 180)
+
+telnet_srv:listen(23, function(socket)
+    local fifo = {}
+    local fifo_drained = true
+
+    local function sender(c)
+        if #fifo > 0 then
+            c:send(table.remove(fifo, 1))
+        else
+            fifo_drained = true
+        end
+    end
+
+    local function s_output(str)
+        table.insert(fifo, str)
+        if socket ~= nil and fifo_drained then
+            fifo_drained = false
+            sender(socket)
+        end
+    end
+
+    node.output(s_output, 1)   -- re-direct output to function s_ouput.
+
+    socket:on("receive", function(c, l)
+        node.input(l)           -- works like pcall(loadstring(l)) but support multiple separate line
+    end)
+    socket:on("disconnection", function(c)
+        node.output(nil)        -- un-regist the redirect output function, output goes to serial
+    end)
+    socket:on("sent", sender)
+
+    print("Welcome to NodeMCU world.")
+end)
+
+print("Telnet server running...")