[1.45] Rednet.send modifies any bytes > 127

local l = ""
for n,side in pairs(rs.getSides()) do
	if peripheral.getType(side) == "modem" then
		rednet.open(side)
		open = true
		break
	end
end

for i = 127 - 15, 127 + 16 * 4 do
	l = l .. string.char(i)
end
local args = {...}
rednet.send(tonumber(args[1]), l)
function memdmp(data)
	write("01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16\n")
  
	for i = 1, #data do
		write(string.format("%.2x ", string.byte(data:sub(i,i))))
	  
		if i % 16 == 0 then
			print()
		end
	  
		if i % 256 == 0 then
			print("Press any key to continue")
			os.pullEvent()
			write("01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16\n")
		end
	end  
	print()
end
memdmp(l)

for n,side in pairs(rs.getSides()) do
	if peripheral.getType(side) == "modem" then
		rednet.open(side)
		open = true
		break
	end
end
local event, p1, p2 = os.pullEvent()
function memdmp(data)
	write("01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16\n")
  
	for i = 1, #data do
		write(string.format("%.2x ", string.byte(data:sub(i,i))))
			  
		if i % 16 == 0 then
			print()
		end
	  
		if i % 256 == 0 then
			print("Press any key to continue")
			os.pullEvent()
			write("01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16\n")
		end
	end  
	print()
end
memdmp(p2)

t = {num1, num2, num3 ... }
rednet.send(id, textutils.serialize(t))


id, ts = rednet.receive()
t = textutils.unserialize(ts)

ElvishJerricco, on 24 October 2012 - 07:18 AM said:

Actually not a bug with CC. Not a bug at all in fact. ASCII only goes up to 127. So converting a number to an ASCII symbol then back will lose anything over 127 because the number will be encoded into the ASCII character represented by 0 because it's unknown, which will be decoded to 0. Try sending the data in a table.

Cloudy, on 24 October 2012 - 09:45 AM said:

I'll look into it - but we don't do anything to the string which is passed java side. We merely pass it as an argument to the other modems receive function. So it looks like something is being lost in conversion from Lua to Java - which may be beyond our control.

Sebra, on 24 October 2012 - 04:01 PM said:

ElvishJerricco, on 24 October 2012 - 07:18 AM said:

Actually not a bug with CC. Not a bug at all in fact. ASCII only goes up to 127. So converting a number to an ASCII symbol then back will lose anything over 127 because the number will be encoded into the ASCII character represented by 0 because it's unknown, which will be decoded to 0. Try sending the data in a table.

Bug it or not this is bad. String message can be not a 7bit ASCII only. It can be not even 8bit letters. It is just a string value which should be delivered unchanged.
Sending chars as a table is like a byte reading/writing. I think binary io in CC is so bad exactly because of that ASCII recoding.

Cloudy, on 24 October 2012 - 09:45 AM said:

I'll look into it - but we don't do anything to the string which is passed java side. We merely pass it as an argument to the other modems receive function. So it looks like something is being lost in conversion from Lua to Java - which may be beyond our control.

It seems Java count it as text and apply recoding ^_^/>/> Thanks for your efforts!

faubiguy, on 24 October 2012 - 08:17 PM said:

I don't see a reason for rednet.send to send strings in the context of ASCII. A string in lua is a series of bytes, and doesn't necessarily store text, ASCII or otherwise. A string can be used to store a sequence of arbitrary bytes. However, as mentioned above, this is likely unintended result of conversion to java and back, and can't be easily fixed.

Cloudy, on 24 October 2012 - 09:45 AM said:

I'll look into it - but we don't do anything to the string which is passed java side. We merely pass it as an argument to the other modems receive function. So it looks like something is being lost in conversion from Lua to Java - which may be beyond our control.

ElvishJerricco, on 25 October 2012 - 04:33 AM said:

faubiguy, on 24 October 2012 - 08:17 PM said:

I don't see a reason for rednet.send to send strings in the context of ASCII. A string in lua is a series of bytes, and doesn't necessarily store text, ASCII or otherwise. A string can be used to store a sequence of arbitrary bytes. However, as mentioned above, this is likely unintended result of conversion to java and back, and can't be easily fixed.

It's because he's using string.char() and string.byte(). Those functions' purpose are to convert a number to its ASCII character and back. Like i said, strings in lua are objects, so it's not the string's fault. It's the method used to go from number to string. The purpose is to use the ASCII standard which really should behave the way it is here. It is not a bug, it is not bad behavior, it is not Java's fault. It is exactly what it was designed to be.

--[[
  BINARY READ / WRITE
]]--
local function readAsString(fileParth) -- big thanks to Immibis
if fs.exists(fileParth) then
  if not fs.isDir(fileParth) then
   local output = ""
   local file = fs.open(fileParth,"rb")
   local dec = file:read()
   while dec do
    sChar = string.char(dec)
    output = output..sChar
    dec = file:read()
   end
   return output
  else
   error("ERROR folder not file")
  end
else
  error("ERROR File not found")
end
end
local function writeString2Binary(fileParth,sDATA) -- big thanks to MysticT
file = fs.open(fileParth,"wb")
if file then
  for i = 1,#sDATA do
   file.write(string.byte(sDATA,i))
  end
  file:close()
  return true
end
end
local sFile = readAsString("rom/user/sound/rihanna-where_have_you_been_version_2.mid")
print(sFile)
writeString2Binary("testA",sFile)

BigSHinyToys, on 25 October 2012 - 04:45 AM said:

ElvishJerricco, on 25 October 2012 - 04:33 AM said:

faubiguy, on 24 October 2012 - 08:17 PM said:

I don't see a reason for rednet.send to send strings in the context of ASCII. A string in lua is a series of bytes, and doesn't necessarily store text, ASCII or otherwise. A string can be used to store a sequence of arbitrary bytes. However, as mentioned above, this is likely unintended result of conversion to java and back, and can't be easily fixed.

It's because he's using string.char() and string.byte(). Those functions' purpose are to convert a number to its ASCII character and back. Like i said, strings in lua are objects, so it's not the string's fault. It's the method used to go from number to string. The purpose is to use the ASCII standard which really should behave the way it is here. It is not a bug, it is not bad behavior, it is not Java's fault. It is exactly what it was designed to be.

you are incorrect those functions work perfectly fine with binary example with the bellow code it is possible to load a file example a MIDI into a string and save it again causing no detrimental effects to the file it can be played after and it is not a ascii file.

Spoiler

--[[
  BINARY READ / WRITE
]]--
local function readAsString(fileParth) -- big thanks to Immibis
if fs.exists(fileParth) then
  if not fs.isDir(fileParth) then
   local output = ""
   local file = fs.open(fileParth,"rb")
   local dec = file:read()
   while dec do
	sChar = string.char(dec)
	output = output..sChar
	dec = file:read()
   end
   return output
  else
   error("ERROR folder not file")
  end
else
  error("ERROR File not found")
end
end
local function writeString2Binary(fileParth,sDATA) -- big thanks to MysticT
file = fs.open(fileParth,"wb")
if file then
  for i = 1,#sDATA do
   file.write(string.byte(sDATA,i))
  end
  file:close()
  return true
end
end
local sFile = readAsString("rom/user/sound/rihanna-where_have_you_been_version_2.mid")
print(sFile)
writeString2Binary("testA",sFile)

BigSHinyToys, on 25 October 2012 - 05:13 AM said:

there s 256 values ranging from 0 to 255 so 256 will always fail as it is above that. also MIDI files are not text in nature
this is what one looks like when opened by Notepad ++

Spoiler

dan200, on 25 October 2012 - 03:21 PM said:

Is this rednet over bundled cable or rednet over modems?

dan200, on 25 October 2012 - 03:23 PM said:

Rednet isn't for sending "bytes", it's for sending strings of text. if you're trying to use strings to encode binary data using string.char/string.byte, you're making a lot of assumptions about character sets that may not hold true. If you really -must- send data in binary (i can't think why you would, sending the lua data you want using textutils.serialise, or just strings of numbers, is much simpler), write a base64 encoder.

ElvishJerricco, on 25 October 2012 - 04:33 AM said:

faubiguy, on 24 October 2012 - 08:17 PM said:

I don't see a reason for rednet.send to send strings in the context of ASCII. A string in lua is a series of bytes, and doesn't necessarily store text, ASCII or otherwise. A string can be used to store a sequence of arbitrary bytes. However, as mentioned above, this is likely unintended result of conversion to java and back, and can't be easily fixed.

It's because he's using string.char() and string.byte(). Those functions' purpose are to convert a number to its ASCII character and back. Like i said, strings in lua are objects, so it's not the string's fault. It's the method used to go from number to string. The purpose is to use the ASCII standard which really should behave the way it is here. It is not a bug, it is not bad behavior, it is not Java's fault. It is exactly what it was designed to be.

Cloudy, on 25 October 2012 - 07:22 PM said:

A simple solution is base64 :P/>/>

Packet size is not important in a system where packet size is unlimited.