1 files changed, 60 insertions, 0 deletions
diff --git a/service.lua b/service.lua
new file mode 100644
index 0000000..70a3374
--- /dev/null
+++ b/service.lua
@@ -0,0 +1,60 @@
+local http_rq = require 'http.request'
+local json = require 'json'
+local lmdb = require 'lmdb'
+
+local M = {}
+
+local db
+local function get_db()
+	if db then
+		return db
+	end
+	db = assert(lmdb.open("data/cache.mdb", {nosubdir = true, mapsize = 2^20}))
+	return db
+end
+
+function M.lookup(domain)
+	if not domain:match "^[%w_%-%.]+$" then
+		return nil, "invalid service name!"
+	end
+	domain = domain:gsub('%.+', ".")
+
+	local db = get_db()
+
+	local txn = db:txn_begin()
+	if txn then
+		local cache = txn:open()
+		if cache[domain] then
+			local sv = json.decode(cache[domain])
+			if os.time() <= sv.expires then
+				txn:commit()
+				return sv
+			end
+		end
+		txn:commit()
+	end
+
+	local meta_uri = "https://"..domain.."/.well-known/citrons/auth"
+	local rq = http_rq.new_from_uri(meta_uri)
+	local headers, stream = rq:go(8)
+	if not headers then return nil, stream end
+	if headers:get ":status" ~= "200" then
+		return nil, "HTTP error: "..headers:get ":status"
+	end
+	local data, err = stream:get_body_chars(4096, 4)
+	if not data then return nil, err end
+	local ok, result = pcall(json.decode, data)
+	if not ok then return nil, "could not decode JSON" end
+	
+	local txn = db:txn_begin(true)
+	if txn then
+		local cache = txn:open()
+		result.expires = os.time() + (result.ttl or 300)
+		cache[domain] = json.encode(result)
+		pcall(txn.commit, txn)
+	end
+
+	return result
+end
+
+return M