Some to/from inet address + cidr utilities.

inet.clj

(ns utils)

;;-----------------------------------------------------------------------------
;; Utils

(defn- expt
  [x pow]
  (apply * (repeat pow x)))

(defn- shft
  [num to]
  (bit-shift-right (bit-and num (bit-shift-left 0xff to)) to))

;;-----------------------------------------------------------------------------
;; Interface

(defn ip->num
  [[a b c d]]
  (+ (* a (expt 256 3))
     (* b (expt 256 2))
     (* c 256)
     d))

(defn num->ip
  [num]
  [(shft num 24)
   (shft num 16)
   (shft num 8)
   (bit-and num 0xFF)])

(defn cidr->ips
  [a b c d len]
  (let [nw (ip->num [a b c d])
        mask (bit-shift-left -1 (- 32 len))
        low (bit-and nw mask)
        high (+ low (bit-not mask))]
    [low high]))

(defn in-cidr-range?
  [[a b c d len] [w x y z]]
  (let [[low high] (cidr->ips a b c d len)
        val (ip->num [w x y z])]
    (and (>= val low)
         (<= val high))))

(defn gen-ip
  ([]
     (gen-ip []))
  ([quads]
     (loop [q quads]
       (if (= (count q) 4)
         q
         (recur (conj q (rand-int 256)))))))