Lua 实现 client-server 聊天

服务端程序

local socket = require("socket")
local server = socket.try(socket.bind("*", 1234))
local ip, port = server:getsockname()
while 1 do
    local client = server:accept()
    client:settimeout(10)
    local line, err = client:receive()
    print (line)
    print("请输入信息：")
    if not err then client:send(io.read().."\n")  end
    client:close()
end

客户端程序

local host, port = "*", 1234
local socket = require("socket")
local tcp = assert(socket.tcp())
tcp:connect(host, port);
tcp:send("已建立连接\n");
while 1 do
    local s, status, partial = tcp:receive()
    print(s or partial)
    print("请输入信息：")
    tcp:send(io.read().."\n");
    if status == "closed" then break end
end
tcp:close()

服务端程序可以向客户端发送消息，但是客户端无法向服务端发送消息。有办法解决吗？