Added useful address calculation code to lua contrib scripts

contrib/lua/cjdns/addrcalc.lua

@@ -0,0 +1,75 @@
+-- Cjdns address conversion functions
+-- Translated from Cjdns C code to lua code by Alex <alex@portlandmeshnet.org>
+
+--- @module cjdns.addrcalc
+local addrcalc = {}
+
+local bit32 = require("bit32")
+local sha2 = require("sha2")
+
+function addrcalc.Base32_decode(input)
+	local numForAscii = {
+			99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,
+			99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,
+			99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,
+			0, 1, 2, 3, 4, 5, 6, 7, 8, 9,99,99,99,99,99,99,
+			99,99,10,11,12,99,13,14,15,99,16,17,18,19,20,99,
+			21,22,23,24,25,26,27,28,29,30,31,99,99,99,99,99,
+			99,99,10,11,12,99,13,14,15,99,16,17,18,19,20,99,
+			21,22,23,24,25,26,27,28,29,30,31,99,99,99,99,99,
+		}
+	
+	local output = {}
+	local outputIndex = 0
+	local inputIndex = 0
+	local nextByte = 0
+	local bits = 0
+	
+	while inputIndex < string.len(input) do
+		i = string.byte(input,inputIndex+1)
+		if bit32.band(i,0x80) ~= 0 then
+			error("Bad base32 decode input character " .. i)
+		end
+		
+		b = numForAscii[i+1]
+		inputIndex = inputIndex + 1
+		if b > 31 then
+			error("Bad base32 decode input character " .. i)
+		end
+		
+		nextByte = bit32.bor(nextByte, bit32.lshift(b, bits))
+		bits = bits + 5
+		
+		if bits >= 8 then
+			output[outputIndex+1] = bit32.band(nextByte, 0xff)
+			outputIndex = outputIndex + 1
+			bits = bits - 8
+			nextByte = bit32.rshift(nextByte, 8)
+		end
+	end
+	
+	if bits >= 5 or nextByte ~= 0 then
+		error("Bad base32 decode input, bits is " .. bits .. " and nextByte is " .. nextByte);
+	end
+	
+	return string.char(unpack(output));
+end
+
+
+function addrcalc.pkey2ipv6(k)
+	if string.sub(k,-2) ~= ".k" then
+		error("Invalid key")
+	end
+	
+	kdata = addrcalc.Base32_decode(string.sub(k,1,-3))
+	hash = sha2.sha512(kdata)
+	hash = sha2.sha512hex(hash)
+	addr = string.sub(hash,1,4)
+	for i = 2,8 do
+		addr = addr .. ":" .. string.sub(hash,i*4-3,i*4)
+	end
+	
+	return addr
+end
+
+return addrcalc