CCFTP Client

-- CCFTP Client
local recv_port = 891
local send_port = 890
local modem = peripheral.find("modem")
-- Characters
local b = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

-- Encoding
function b64encode(data)
    return ((data:gsub('.', function(x)
        local r,b='',x:byte()
        for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
        return r;
    end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
        if (#x < 6) then return '' end
        local c=0
        for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
        return b:sub(c+1,c+1)
    end)..({ '', '==', '=' })[#data%3+1])
end

-- Decoding
function b64decode(data)
    data = string.gsub(data, '[^'..b..'=]', '')
    return (data:gsub('.', function(x)
        if (x == '=') then return '' end
        local r,f='',(b:find(x)-1)
        for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
        return r;
    end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
        if (#x ~= 8) then return '' end
        local c=0
        for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
        return string.char(c)
    end))
end
modem.open(recv_port)

while true do
term.setCursorPos(1,1)
term.clear()
term.write("filename: ")
local fname = read()
if fname == "file1" then
modem.transmit(send_port,send_port,"file1")
 local event, modemSide, senderChannel, replyChannel, message, senderDistance = os.pullEvent("modem_message")
 local h = fs.open("file.dwnload", "w")
 h.write(b64decode(message))
 h.close()
end end