add 206 partial content in Aleph

206

; ---- the following fns copied from ring.util.response because they were
; useful but private ----

(defn canonical-path [^File file]
  (str (.getCanonicalPath file)
       (if (.isDirectory file) File/separatorChar)))

(defn safe-path? [^String root ^String path]
  (.startsWith (canonical-path (File. root path))
               (canonical-path (File. root))))

(defn directory-transversal?
  "Check if a path contains '..'."
  [^String path]
  (-> (str/split path #"/|\\")
      (set)
      (contains? "..")))

(defn find-file-named [^File dir ^String filename]
  (let [path (File. dir filename)]
    (if (.isFile path)
      path)))

(defn find-file-starting-with [^File dir ^String prefix]
  (first
   (filter
    #(.startsWith (.toLowerCase (.getName ^File %)) prefix)
    (.listFiles dir))))

(defn find-index-file
  "Search the directory for an index file."
  [^File dir]
  (or (find-file-named dir "index.html")
      (find-file-named dir "index.htm")
      (find-file-starting-with dir "index.")))

(defn safely-find-file [^String path opts]
  (if-let [^String root (:root opts)]
    (if (or (safe-path? root path)
            (and (:allow-symlinks? opts) (not (directory-transversal? path))))
      (File. root path))
    (File. path)))

(defn find-file [^String path opts]
  (if-let [^File file (safely-find-file path opts)]
    (cond
      (.isDirectory file)
        (and (:index-files? opts true) (find-index-file file))
      (.exists file)
        file)))

(defn content-length [resp len]
  (if len
    (rr/header resp "Content-Length" len)
    resp))


; ---- handle 206 partial content requests


(defn partial-file-data [^File file from lenth]
  (info "  partial file:" from lenth)
  (let [
        f (RandomAccessFile. file "r")
        c (.getChannel f)
        b (.map c FileChannel$MapMode/READ_ONLY from lenth)
        ]
    (try
      (bs/to-byte-array b)
      (finally (.close c)))))

; "bytes=500-999"
(defn parse-range [s]
  (debug "parse range " s)
  (let [[_ & s] (string/split s #"=|-")]
    (map (fn [s] (Long/parseLong s)) s)))

(defn partial-file-response
  [root {{uuid :uuid pfrom :from pto :to} :params :as req}]
  (debug (str "partial file request " root req))
  (let [filepath (str root uuid) opts nil]
    (if-let [file (find-file filepath opts)]
     (let [
           total-length (.length file)
           range-str (get-in req [:headers "Range"])
           [from to]
             (if range-str
               (parse-range range-str)
               (if (and pfrom pto)
                 (map (fn [s] (Long/parseLong s)) [pfrom pto])
                 [0 total-length]))
           to (min (or to total-length) total-length)
           from (max 0 (or from 0))
           lenth (- to from)
           ]
       (debug "206 range" from to lenth )
       (if (> to from)
         (let [data (partial-file-data file from lenth)]
           {:status 206
            :headers
                    {
                     "Content-Length" lenth
                     "Content-Range"  (str "bytes " from "-" to "/" total-length)
                     }
            :body   data})
         {:status 400 :body "invalid range"})))))