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OC-Minitel/TCPBridge/interminitel.lua

45 lines
1.2 KiB
Lua

local imt = {}
function imt.to16bn(n)
return string.char(math.floor(n/256))..string.char(math.floor(n%256))
end
function imt.from16bn(s)
return (string.byte(s,1,1)*256)+string.byte(s,2,2)
end
function imt.encodePacket(packetID, packetType, destination, sender, port, data)
local rs = string.char(packetID:len()%256)..packetID..string.char(packetType)
rs=rs..string.char(destination:len()%256)..destination
rs=rs..string.char(sender:len()%256)..sender
rs=rs..to16bn(port)
rs=rs..to16bn(data:len())..data
return rs
end
function imt.decodePacket(s)
local pidlen, destlen, senderlen, datalen, packetID, packetType, destination, sender, port, data
pidlen = string.byte(s:sub(1,1))
s=s:sub(2)
packetID = s:sub(1,pidlen)
s=s:sub(pidlen+1)
packetType = string.byte(s:sub(pidlen+1))
s=s:sub(2)
destlen = string.byte(s:sub(1,1))
s=s:sub(2)
destination = s:sub(1,destlen)
s=s:sub(destlen+1)
senderlen=string.byte(s:sub(1,1))
s=s:sub(2)
sender = s:sub(1,senderlen)
s=s:sub(senderlen+1)
port=from16bn(s:sub(1,2))
s=s:sub(3)
datalen=from16bn(s:sub(1,2))
s=s:sub(3)
data=s:sub(1,datalen)
s=s:sub(datalen+1)
return packetID, packetType, destination, sender, port, data, s
end
return imt