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Fix code_verifier token randomness #10424

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Fix code_verifier token randomness #10424

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34 changes: 25 additions & 9 deletions src/Classes/PoEAPI.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,23 @@ local scopesOAuth = {

local filename = "poe_api_response.json"

local function randomBytes(count)
local ffi = require("ffi")
if ffi.os == "Windows" then
ffi.cdef[[long __stdcall BCryptGenRandom(void*, unsigned char*, unsigned long, unsigned long);]]
local buffer = ffi.new("unsigned char[?]", count)
if ffi.load("bcrypt").BCryptGenRandom(nil, buffer, count, 2) ~= 0 then
error("Could not generate OAuth verifier")
end
return ffi.string(buffer, count)
end
local file = assert(io.open("/dev/urandom", "rb"), "Could not open OS random source")
local bytes = file:read(count)
file:close()
assert(bytes and #bytes == count, "Could not generate OAuth verifier")
return bytes
end

---@class PoEAPI
local PoEAPIClass = newClass("PoEAPI")

Expand Down Expand Up @@ -70,7 +87,7 @@ end

--- @param secret string
local function base64_encode(secret)
return base64.encode(secret):gsub("+", "-"):gsub("/", "_"):gsub("=$", "")
return base64.encode(secret):gsub("+", "-"):gsub("/", "_"):gsub("=+$", "")
end

--- resets current authorization details
Expand All @@ -91,15 +108,14 @@ end

--- @param callback fun(errCode: string?)
function PoEAPIClass:FetchAuthToken(callback)
math.randomseed(os.time())
local secret = math.random(2 ^ 32 - 1)
local code_verifier = base64_encode(tostring(secret))
local ok, secret = pcall(randomBytes, 48)
if not ok then
callback("Could not generate secure OAuth verifier")
return
end
local code_verifier = base64_encode(secret:sub(1, 32))
local code_challenge = base64_encode(sha.hex_to_bin(sha.sha256(code_verifier)))

-- 16 character hex string
local initialState = string.gsub('xxxxxxxxxxxxxxxx', 'x', function()
return string.format('%x', math.random(0, 0xf))
end)
local initialState = base64_encode(secret:sub(33))

local authUrl = string.format(
"https://www.pathofexile.com/oauth/authorize?client_id=pob&response_type=code&scope=%s&state=%s&code_challenge=%s&code_challenge_method=S256"
Expand Down
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