tiny-gopherd/gopherd.lua

local socket = require "socket"
local fs = require "lfs"

local tArgs = {...}

local pcount = 0
local threads = {}

-- initial configuration
local config = {}
config.path = "/var/www/gopher"
config.hostname = "shadowkat.net"
config.port = 70
config.bindport = 7000
config.dirinfo = true
config.timer = 0.1
config.cgi = true
--config.cgipattern = ".*" -- todo

-- load the config as a lua script
if tArgs[1] then
 local f = io.open(tArgs[1],"rb")
 local fn = load(f:read("*a"))
 f:close()
 if fn then
  for k,v in pairs(fn()) do
   config[k] = v
  end
 end
end

local function cleanPath(p) -- canonicalizes the path in theory
 local t,o = {},""
 for s in p:gmatch("[^/]+") do
  if s == ".." then
   t[#t] = nil
  else
   t[#t+1] = s
  end
 end
 for k,v in pairs(t) do
  o=o.."/"..v
 end
 return o
end

local function logerr(msg)
 -- todo: proper error logging logic
 print("error: "..msg)
end

local function detectft(path) -- tries to detect the file type
 local attr = fs.attributes(path)
 if attr.mode:sub(1,3) == "dir" then
  return "1"
 end
 if path:sub(-4) == ".png" or path:sub(-4) == ".jpg" or path:sub(-5) == ".jpeg" or path:sub(-4) == ".bmp" or path:sub(-4) == "gif" then
  return "I"
 elseif path:sub(-5) == ".html" or path:sub(-4) == ".htm" then
  return "h"
 elseif path:sub(-10) == ".gopherdir" then
  return "1"
 end
 return "0"
end

local function handleConnect(client)
 client:settimeout(0)
 threads[pcount+1] = coroutine.create(function() local w,err = pcall(function()
  local host,port = client:getsockname()
  repeat
   coroutine.yield()
   line=client:receive()
  until line
  print(string.format("%s:%d: %s",host,port,line))
  local path,args = config.path .. cleanPath(line)
  local attr = fs.attributes(path)
  if attr then
   if attr.mode:sub(1,3) == "dir" then
    if lfs.attributes(path.."/.gopherdir.cgi") and config.cgi then
     local f = io.popen(path.."/.gopherdir.cgi")
     coroutine.yield()
     client:send(f:read("*a"))
     f:close()
    elseif lfs.attributes(path.."/.gopherdir") then
     local f = io.open(path.."/.gopherdir")
     client:send(f:read("*a"))
     f:close()
    else
     if config.dirinfo then
      client:send(string.format("i%s\ni%s\n",config.hostname,cleanPath(line)))
     end
     for file in lfs.dir(path) do
      if file:sub(1,1) ~= "." then
       client:send(string.format("%s%s\t%s\t%s\t%d\n",detectft(path.."/"..file),file,string.format("%s/%s",cleanPath(line),file),config.hostname,config.port))
      end
     end
    end
   else
    if path:sub(-4) == ".cgi" and config.cgi then
     local f = io.popen(path)
     coroutine.yield()
     client:send(f:read("*a"))
     f:close()
    else
     local f = io.open(path)
     client:send(f:read("*a"))
     f:close()
    end
   end
  else
   client:send("Not found.")
  end
  client:close()
 end)
 if not w then
  logerr(err)
  client:close()
 end
 end)
 pcount=pcount+1
end

local server = socket.bind("*",config.bindport)
while true do -- totally not a scheduler
 client = server:accept()
 if client then
  server:settimeout(config.timer)
  handleConnect(client)
 end
 local c = 0
 for k,v in pairs(threads) do
  if coroutine.status(v) == "dead" then
   threads[k] = nil
  else
   coroutine.resume(v)
   c = c + 1
  end
 end
 if c == 0 then
  -- if there are no clients connected, make server:accept() block forever
  server:settimeout(inf)
 end
end