A Simple Clojure IRC Client

The other night I was toying with the following script, I was going to thrash it but figured it may help someone or me later on so I am dumping it here. It doesn't do anything other then to sit idle in a channel, 

(ns irc
  (:import (java.net Socket)
           (java.io PrintWriter InputStreamReader BufferedReader)))

(def freenode {:name "irc.freenode.net" :port 6667})
(def user {:name "Nurullah Akkaya" :nick "nakkaya"})

(declare conn-handler)

(defn connect [server]
  (let [socket (Socket. (:name server) (:port server))
        in (BufferedReader. (InputStreamReader. (.getInputStream socket)))
        out (PrintWriter. (.getOutputStream socket))
        conn (ref {:in in :out out})]
    (doto (Thread. #(conn-handler conn)) (.start))
    conn))

(defn write [conn msg]
  (doto (:out @conn)
    (.println (str msg "\r"))
    (.flush)))

(defn conn-handler [conn]
  (while (nil? (:exit @conn))
    (let [msg (.readLine (:in @conn))]
      (println msg)
      (cond 
       (re-find #"^ERROR :Closing Link:" msg) 
       (dosync (alter conn merge {:exit true}))
       (re-find #"^PING" msg)
       (write conn (str "PONG "  (re-find #":.*" msg)))))))

(defn login [conn user]
  (write conn (str "NICK " (:nick user)))
  (write conn (str "USER " (:nick user) " 0 * :" (:name user))))

(def irc (connect freenode))
(login irc user)
(write irc "JOIN #clojure")
(write irc "QUIT")

Lots of this code should be self-explanatory, calling connect will open a socket to the server, it will return a ref containing a reader and a writer associated with the socket, it will also spawn a new thread that will handle incoming messages from the server.

conn-handler will keep reading and printing from the socket until exit key in the conn ref is set which happens when we receive a "Closing Link" message from the server, every once in a while server will ping us with "PING :randomstring" we need to reply "PONG :randomstring" else we get disconnected. Thats all there is to it, as I said it doesn't do anything but with a few regexes you can turn it in to client or a bot.

Tags: clojure network