babashka/examples/notes.clj
2021-03-09 10:58:27 +01:00

152 lines
5.5 KiB
Clojure
Executable file

#!/usr/bin/env bb
;; Note that babashka comes with org.httpkit.server now, so you don't need to
;; build an http server from scratch anymore like we do here. We should update
;; this script to the built-in webserver. Whoever reads this is welcome to
;; submit a PR.
(import (java.net ServerSocket))
(require '[clojure.java.io :as io]
'[clojure.string :as str])
(def debug? true)
(def user "admin")
(def password "admin")
(def base64 (-> (.getEncoder java.util.Base64)
(.encodeToString (.getBytes (str user ":" password)))))
(def notes-file (io/file (System/getProperty "user.home") ".notes" "notes.txt"))
(def file-lock (Object.))
(defn write-note! [note]
(locking file-lock
(io/make-parents notes-file)
(spit notes-file (str note "\n") :append true)))
;; hiccup-like
(defn html [v]
(cond (vector? v)
(let [tag (first v)
attrs (second v)
attrs (when (map? attrs) attrs)
elts (if attrs (nnext v) (next v))
tag-name (name tag)]
(format "<%s%s>%s</%s>\n" tag-name (html attrs) (html elts) tag-name))
(map? v)
(str/join ""
(map (fn [[k v]]
(format " %s=\"%s\"" (name k) v)) v))
(seq? v)
(str/join " " (map html v))
:else (str v)))
(defn write-response [out session-id status headers content]
(let [cookie-header (str "Set-Cookie: notes-id=" session-id)
headers (str/join "\r\n" (conj headers cookie-header))
response (str "HTTP/1.1 " status "\r\n"
(str headers "\r\n")
"Content-Length: " (if content (count content)
0)
"\r\n\r\n"
(when content
(str content)))]
(when debug? (println response))
(binding [*out* out]
(print response)
(flush))))
;; the home page
(defn home-response [out session-id]
(let [body (str
"<!DOCTYPE html>\n"
(html
[:html
[:head
[:title "Notes"]]
[:body
[:h1 "Notes"]
[:pre (when (.exists notes-file)
(slurp notes-file))]
[:form {:action "/" :method "post"}
[:input {:type "text" :name "note"}]
[:input {:type "submit" :value "Submit"}]]]]))]
(write-response out session-id "200 OK" nil body)))
(defn basic-auth-response [out session-id]
(write-response out session-id
"401 Unauthorized"
["WWW-Authenticate: Basic realm=\"notes\""]
nil))
(def known-sessions
(atom #{}))
(defn new-session! []
(let [uuid (str (java.util.UUID/randomUUID))]
(swap! known-sessions conj uuid)
uuid))
(defn get-session-id [headers]
(if-let [cookie-header (first (filter #(str/starts-with? % "Cookie: ") headers))]
(let [parts (str/split cookie-header #"; ")]
(if-let [notes-id (first (filter #(str/starts-with? % "notes-id") parts))]
(str/replace notes-id "notes-id=" "")
(new-session!)))
(new-session!)))
(defn basic-auth-header [headers]
(some #(str/starts-with? % "Basic-Auth: ") headers))
(def authenticated-sessions
(atom #{}))
(defn authenticate! [session-id headers]
(or (contains? @authenticated-sessions session-id)
(when (some #(= % (str "Authorization: Basic " base64)) headers)
(swap! authenticated-sessions conj session-id)
true)))
;; run the server
(with-open [server-socket (let [s (new ServerSocket 8080)]
(println "Server started on port 8080.")
s)]
(loop []
(let [client-socket (.accept server-socket)]
(future
(with-open [conn client-socket]
(try
(let [out (io/writer (.getOutputStream conn))
is (.getInputStream conn)
in (io/reader is)
[_req & headers :as response]
(loop [headers []]
(let [line (.readLine in)]
(if (str/blank? line)
headers
(recur (conj headers line)))))
session-id (get-session-id headers)
form-data (let [sb (StringBuilder.)]
(loop []
(when (.ready in)
(.append sb (char (.read in)))
(recur)))
(-> (str sb)
(java.net.URLDecoder/decode)))
_ (when debug? (println (str/join "\n" response)))
_ (when-not (str/blank? form-data)
(when debug? (println form-data))
(let [note (str/replace form-data "note=" "")]
(write-note! note)))
_ (when debug? (println))]
(cond
;; if we didn't see this session before, we want the user to re-authenticate
(not (contains? @known-sessions session-id))
(let [uuid (new-session!)]
(basic-auth-response out uuid))
(not (authenticate! session-id headers))
(basic-auth-response out session-id)
:else (home-response out session-id)))
(catch Throwable t
(binding [*err* *out*]
(println t)))))))
(recur)))