wtf.clj

(ns mbox.harpo.mbx-signature
  (:use
   [clojure
    [walk      :only (keywordize-keys stringify-keys)]]
   
   [clojure.contrib
    [java-utils :only (as-str)]
    [str-utils  :only (chomp str-join)]
    [except     :only (throw-arg)]])
  
  (:import
   [java.security SignatureException]
   [javax.crypto Mac]
   [javax.crypto.spec SecretKeySpec]
   [org.apache.commons.codec.binary Base64]
   [java.util Date]
   [java.text SimpleDateFormat FieldPosition]
   [java.net URLEncoder]
   ))

(def *hmac-algo* "HmacSHA256")
(def *base64-url-safe* false)
(def *encoding* "UTF8")

(defonce *rfc3339-date-fmt* (SimpleDateFormat. "yyyy-MM-dd'T'HH:mm:ss'Z'"))

(defn- throw-arg-if-not [test & args]
  (when-not test
    (apply throw-arg args)))


(defn format-rfc-3339 [date]
  (str (.format *rfc3339-date-fmt* date (StringBuffer.) (FieldPosition. 0))))

(defn urlescape [s]
  (URLEncoder/encode (as-str s) *encoding*))

(defstruct mbx-signature :key :secret :verb :host :path :query-params :time :body)

(defn- date? [o]
  (= (class o) Date))

(defn canonicalize-params [time key params]
  
  (throw-arg-if-not (or (date? time) (string? time))
                    (str "time argument to canonicalize-params must be either "
                         "a java.util.Date or a formatted string, not %s") time)
  
  (let [time-str (if (date? time)
                   (format-rfc-3339 time)
                   time)
        
        pmap     (merge (stringify-keys params)
                        {"ts" time-str "key" key})]

    (str-join "&" (map #(str-join "=" %1 %2) (sort pmap)))))


(defn sign [{:keys [key secret verb host path query-params time body]
             :or {time (Date.) query-params {}} }]
  (let [time-str (format-rfc-3339 time)]))

(defn calculate [data secret]
  (let [skey (SecretKeySpec. (.getBytes secret) *hmac-algo*)
        mac  (doto (Mac/getInstance *hmac-algo*)
               (.init skey))
        b64  (Base64. *base64-url-safe*)]
    
    (->> (.doFinal mac (.getBytes data))
         (.encodeToString b64)
         (chomp))))