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-----------------------------------------------------------------------------
-- TFTP support for the Lua language
-- LuaSocket toolkit.
-- Author: Diego Nehab
-- RCS ID: $Id$
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
-- Load required files
-----------------------------------------------------------------------------
local socket = require("socket")
local ltn12 = require("ltn12")
local url = require("url")
-----------------------------------------------------------------------------
-- Program constants
-----------------------------------------------------------------------------
local char = string.char
local byte = string.byte
PORT = 69
local OP_RRQ = 1
local OP_WRQ = 2
local OP_DATA = 3
local OP_ACK = 4
local OP_ERROR = 5
local OP_INV = {"RRQ", "WRQ", "DATA", "ACK", "ERROR"}
-----------------------------------------------------------------------------
-- Packet creation functions
-----------------------------------------------------------------------------
local function RRQ(source, mode)
return char(0, OP_RRQ) .. source .. char(0) .. mode .. char(0)
end
local function WRQ(source, mode)
return char(0, OP_RRQ) .. source .. char(0) .. mode .. char(0)
end
local function ACK(block)
local low, high
low = math.mod(block, 256)
high = (block - low)/256
return char(0, OP_ACK, high, low)
end
local function get_OP(dgram)
local op = byte(dgram, 1)*256 + byte(dgram, 2)
return op
end
-----------------------------------------------------------------------------
-- Packet analysis functions
-----------------------------------------------------------------------------
local function split_DATA(dgram)
local block = byte(dgram, 3)*256 + byte(dgram, 4)
local data = string.sub(dgram, 5)
return block, data
end
local function get_ERROR(dgram)
local code = byte(dgram, 3)*256 + byte(dgram, 4)
local msg
_,_, msg = string.find(dgram, "(.*)\000", 5)
return string.format("error code %d: %s", code, msg)
end
-----------------------------------------------------------------------------
-- The real work
-----------------------------------------------------------------------------
local function tget(gett)
local retries, dgram, sent, datahost, dataport, code
local last = 0
local con = socket.try(socket.udp())
-- convert from name to ip if needed
gett.host = socket.try(socket.dns.toip(gett.host))
con:settimeout(1)
-- first packet gives data host/port to be used for data transfers
retries = 0
repeat
sent = socket.try(con:sendto(RRQ(gett.path, "octet"),
gett.host, gett.port))
dgram, datahost, dataport = con:receivefrom()
retries = retries + 1
until dgram or datahost ~= "timeout" or retries > 5
socket.try(dgram, datahost)
-- associate socket with data host/port
socket.try(con:setpeername(datahost, dataport))
-- default sink
local sink = gett.sink or ltn12.sink.null()
-- process all data packets
while 1 do
-- decode packet
code = get_OP(dgram)
socket.try(code ~= OP_ERROR, get_ERROR(dgram))
socket.try(code == OP_DATA, "unhandled opcode " .. code)
-- get data packet parts
local block, data = split_DATA(dgram)
-- if not repeated, write
if block == last+1 then
socket.try(sink(data))
last = block
end
-- last packet brings less than 512 bytes of data
if string.len(data) < 512 then
socket.try(con:send(ACK(block)))
socket.try(con:close())
socket.try(sink(nil))
return 1
end
-- get the next packet
retries = 0
repeat
sent = socket.try(con:send(ACK(last)))
dgram, err = con:receive()
retries = retries + 1
until dgram or err ~= "timeout" or retries > 5
socket.try(dgram, err)
end
end
local default = {
port = PORT,
path ="/",
scheme = "tftp"
}
local function parse(u)
local t = socket.try(url.parse(u, default))
socket.try(t.scheme == "tftp", "invalid scheme '" .. t.scheme .. "'")
socket.try(t.host, "invalid host")
return t
end
local function sget(u)
local gett = parse(u)
local t = {}
gett.sink = ltn12.sink.table(t)
tget(gett)
return table.concat(t)
end
get = socket.protect(function(gett)
if type(gett) == "string" then return sget(gett)
else return tget(gett) end
end)
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