-- server.lua
-- Simple HTTP server in Lua using LuaSocket
-- Install dependency: luarocks install luasocket
local socket = require("socket")
-- ─── Configuration ────────────────────────────────────────────────────────────
local HOST = "127.0.0.1"
local PORT = 8080
-- ─── In-memory data store ─────────────────────────────────────────────────────
local messages = {} -- stores messages sent from the client
-- ─── Helper: parse the request body from raw HTTP request ─────────────────────
local function parse_body(raw)
-- Body follows the blank line after headers
local body = raw:match("\r\n\r\n(.*)")
return body or ""
end
-- ─── Helper: URL-decode a string ──────────────────────────────────────────────
local function url_decode(str)
str = str:gsub("+", " ")
str = str:gsub("%%(%x%x)", function(h)
return string.char(tonumber(h, 16))
end)
return str
end
-- ─── Helper: parse application/x-www-form-urlencoded body ────────────────────
local function parse_form(body)
local params = {}
for key, value in body:gmatch("([^&=]+)=([^&=]*)") do
params[url_decode(key)] = url_decode(value)
end
return params
end
-- ─── Helper: encode a Lua table as a simple JSON object ───────────────────────
local function to_json(tbl)
local parts = {}
for k, v in pairs(tbl) do
local val
if type(v) == "string" then
val = string.format('"%s"', v:gsub('"', '\\"'))
elseif type(v) == "number" then
val = tostring(v)
elseif type(v) == "boolean" then
val = tostring(v)
else
val = '"[unsupported]"'
end
table.insert(parts, string.format('"%s": %s', k, val))
end
return "{ " .. table.concat(parts, ", ") .. " }"
end
-- ─── Helper: encode a list of messages as a JSON array ────────────────────────
local function messages_to_json()
local items = {}
for _, msg in ipairs(messages) do
table.insert(items, to_json(msg))
end
return "[" .. table.concat(items, ", ") .. "]"
end
-- ─── HTTP response builders ────────────────────────────────────────────────────
local function http_response(status, content_type, body)
return string.format(
"HTTP/1.1 %s\r\nContent-Type: %s\r\nContent-Length: %d\r\nAccess-Control-Allow-Origin: *\r\nConnection: close\r\n\r\n%s",
status, content_type, #body, body
)
end
local function ok_json(body)
return http_response("200 OK", "application/json", body)
end
local function ok_html(body)
return http_response("200 OK", "text/html", body)
end
local function not_found()
return http_response("404 Not Found", "text/plain", "404 Not Found")
end
-- ─── HTML page served to the browser ─────────────────────────────────────────
local HTML = [[
Lua Server Demo
]]
-- ─── Route handler ────────────────────────────────────────────────────────────
local start_time = os.time()
local request_count = 0
local function handle(raw_request)
request_count = request_count + 1
-- Parse method and path from the request line
local method, path = raw_request:match("^(%u+) (/[^ ]*) HTTP")
method = method or "GET"
path = path or "/"
-- GET / → serve the HTML page
if method == "GET" and path == "/" then
return ok_html(HTML)
-- GET /messages → return all stored messages as JSON
elseif method == "GET" and path == "/messages" then
return ok_json(messages_to_json())
-- GET /info → return server metadata as JSON
elseif method == "GET" and path == "/info" then
local info = {
host = HOST,
port = tostring(PORT),
uptime = tostring(os.time() - start_time),
requests = tostring(request_count),
lua_version = _VERSION,
}
return ok_json(to_json(info))
-- POST /send → accept a message from the client
elseif method == "POST" and path == "/send" then
local body = parse_body(raw_request)
local params = parse_form(body)
local name = params["name"] or "Anonymous"
local text = params["message"] or ""
if text == "" then
return ok_json('{ "ok": false, "error": "empty message" }')
end
-- Store the message
table.insert(messages, {
name = name,
text = text,
time = os.date("%H:%M:%S"),
})
print(string.format("[POST /send] %s: %s", name, text))
return ok_json('{ "ok": true }')
else
return not_found()
end
end
-- ─── Main server loop ─────────────────────────────────────────────────────────
local server = assert(socket.bind(HOST, PORT))
server:settimeout(0) -- non-blocking accept
print(string.format("Lua HTTP server running at http://%s:%d/", HOST, PORT))
print("Press Ctrl-C to stop.\n")
while true do
local client = server:accept()
if client then
client:settimeout(5)
-- Read the full request (stop at blank line for GET, read body for POST)
local raw = {}
local content_length = 0
-- Read headers
while true do
local line, err = client:receive("*l")
if not line or line == "" then break end
table.insert(raw, line)
-- Capture Content-Length so we can read the body
local cl = line:match("^[Cc]ontent%-[Ll]ength:%s*(%d+)")
if cl then content_length = tonumber(cl) end
end
local header_str = table.concat(raw, "\r\n") .. "\r\n\r\n"
-- Read body if present
local body_str = ""
if content_length > 0 then
body_str = client:receive(content_length) or ""
end
local full_request = header_str .. body_str
local response = handle(full_request)
client:send(response)
client:close()
end
socket.sleep(0.01) -- prevent busy-loop
end