45 lines
1.4 KiB
Lua
45 lines
1.4 KiB
Lua
-- I, 20kdc, release this into the public domain.
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-- No warranty is provided, implied or otherwise.
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-- 'Copper' networking implementation - encode/decode
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-- Notably, it's fine that culib relies on the hops byte being the first byte,
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-- because culib is supposed to know the protocol anyway,
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-- and thus can rely on things like that.
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-- YOU, on the other hand, cannot -
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-- relib doesn't know or care about protocol internals, for example,
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-- short of some "convenient" nudging of relib header size and maximum Copper data packet size.
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local function encodeName(name)
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if name:len() > 256 then error("Bad name (l>256)") end
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if name == "" then error("No name") end
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return string.char(name:len() - 1) .. name
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end
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local function decodeName(message)
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if message:len() < 2 then return end
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local nlen = message:byte(1) + 1
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local fnam = message:sub(2, nlen + 1)
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if fnam:len() < nlen then return end
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return fnam, message:sub(nlen + 2)
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end
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local function decodeNoHops(data)
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local src, data = decodeName(data)
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if not src then return end
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local dst, data = decodeName(data)
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if not dst then return end
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return src, dst, data
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end
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return {
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encode = function (hops, src, dst, data)
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return string.char(hops) .. encodeName(src) .. encodeName(dst) .. data
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end,
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decode = function (d)
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if d:len() < 3 then return end
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local src, dst, data = decodeNoHops(d:sub(2))
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if not data then return end
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return d:byte(1), src, dst, data
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end,
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decodeNoHops = decodeNoHops
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}
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