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WebSocket subprotocol and origin validation with HTTP Kit
(ns my.server
(:use org.httpkit.server
[clojure.string :only [split trim lower-case]])
(:import [org.httpkit.server AsyncChannel]))
(defn origin-match? [origin-re req]
(if-let [req-origin (get-in req [:headers "origin"])]
(re-matches origin-re req-origin)))
(defn subprotocol? [proto req]
(if-let [protocols (get-in req [:headers "sec-websocket-protocol"])]
(some #{proto}
(map #(lower-case (trim %))
(split protocols #",")))))
(defmacro with-subproto-channel
[request ch-name origin-re subproto & body]
`(let [~ch-name (:async-channel ~request)]
(if (:websocket? ~request)
(if-let [key# (get-in ~request [:headers "sec-websocket-key"])]
(if (origin-match? ~origin-re ~request)
(if (subprotocol? ~subproto ~request)
(do
(.sendHandshake ~(with-meta ch-name {:tag `AsyncChannel})
{"Upgrade" "websocket"
"Connection" "Upgrade"
"Sec-WebSocket-Accept" (accept key#)
"Sec-WebSocket-Protocol" ~subproto})
~@body
{:body ~ch-name})
{:status 400 :body "missing or bad WebSocket-Protocol"})
{:status 400 :body "missing or bad WebSocket-Origin"})
{:status 400 :body "missing or bad WebSocket-Key"})
{:status 400 :body "not websocket protocol"})))
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