function mysplit (inputstr, sep)
        if sep == nil then
                sep = "%s"
        end
        local t={}
        for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
                table.insert(t, str)
        end
        return t
end


function table.slice(tbl, first, last, step)
  local sliced = {}

  for i = first or 1, last or #tbl, step or 1 do
    sliced[#sliced+1] = tbl[i]
  end

  return sliced
end


function validate(data,from,to)
headers = {}
begindata = false
i = 1
while true do
  line = mysplit(data,"\n")[i]
  if line == nil then break end
  if begindata == false then
  line = mysplit(line, ":")
if line[1] == nil then
  begindata = true
  else
headers[line[1]] = line[2]
  end
  
  else
  headers["body"] = (headers["body"] or "") .. line .. "\n"
  end
  i = i + 1
end
if not headers["From"] or not headers["From"]:find(from) then return false end
if not to:find("@doesnm.cc") then return false end
return headers
end

function string.starts(String,Start)
   return string.sub(String,1,string.len(Start))==Start
end

from = nil
to = nil
data = false
dataBuf = ""
print("220 doesnm.cc Simple Mail Transfer Service Ready")

while true do
  line = io.read("*line")
  line = mysplit(line)
  if line[1] == "NOOP" and data == false then
    print("250 OK")
  elseif line[1] == "HELO" then
    if #line < 2 then
    print("251 Command requires argument")
    else
    print("250 Hello " .. line[2])
    end
  elseif line[1] == "EHLO" then
    if #line < 2 then
    print("251 Command requires argument")
    else
    print("250-Hello " .. line[2])
    print("250 SIZE 1000000")
    end
  elseif line[1] == "VRFY" and data == false then
    print("252 Cannot VRFY user, but will accept message")
  elseif line[1] == "QUIT" and data == false then
    print("221 Bye!")
    os.exit()
  elseif line[1] == "MAIL" and data == false then
    if #line < 2 then print("501 Incorrent number of arguments")
    else
    if string.starts(line[2],"FROM:") then
      from = table.concat(table.slice(mysplit(table.concat(line," "),":"),2))
      print("250 OK")
    else
      print("501 Incorrect number of arguments")
    end
    end
  elseif line[1] == "RCPT" and data == false then
    if #line < 2 then
      print("501 Incorrent number of arguments")
    else
    if string.starts(line[2],"TO:") then
to = table.concat(table.slice(mysplit(table.concat(line," "),":"),2))
      print("250 OK")
    else
      print("502 Unrecognized command")
    end
    end
  elseif line[1] == "DATA" and from ~= nil and to ~= nil then
    data = true
    print("354 Send message content; End with <CRLF>.<CRLF>")
  elseif line[1] == "." and data == true then
    if not validate(dataBuf,from,to) then print("250 NOTOK")
      data = false else
    out = io.open("/var/mail/root","a")
    out:write("From " .. from .." ".. os.date("%a %b %d %H:%M:%S %Y") .. "\n")
    out:write(dataBuf)
    out:close()
    print("250 OK")
    data = false
    end
  else
    if data == true then
      dataBuf = dataBuf .. table.concat(line, " ") .. "\n"
    else
    print("502 Unrecognized command")
    end
  end
end