+module Cidr
+( Cidr,
+ from_string,
+ min_first_octet,
+ max_first_octet,
+ min_second_octet,
+ max_second_octet,
+ min_third_octet,
+ max_third_octet,
+ min_fourth_octet,
+ max_fourth_octet
+) where
+
+import Data.Char (digitToInt, intToDigit)
+import Numeric (readInt, showIntAtBase)
+import ListUtils
+
+type Maskbits = Int
+type Octet = Int
+type OctetList = (Octet, Octet, Octet, Octet)
+type BaseTwoOctetList = (String, String, String, String)
+
+data Cidr = Cidr { octet1 :: Octet,
+ octet2 :: Octet,
+ octet3 :: Octet,
+ octet4 :: Octet,
+ maskbits :: Maskbits }
+ deriving (Show)
+
+first :: (a,b,c,d) -> a
+first (w,_,_,_) = w
+
+second :: (a,b,c,d) -> b
+second (_,x,_,_) = x
+
+third :: (a,b,c,d) -> c
+third (_,_,y,_) = y
+
+fourth :: (a,b,c,d) -> d
+fourth (_,_,_,z) = z
+
+min_first_octet :: Cidr -> Octet
+min_first_octet cidr = first (min_octets cidr)
+
+min_second_octet :: Cidr -> Octet
+min_second_octet cidr = second (min_octets cidr)
+
+min_third_octet :: Cidr -> Octet
+min_third_octet cidr = third (min_octets cidr)
+
+min_fourth_octet :: Cidr -> Octet
+min_fourth_octet cidr = fourth (min_octets cidr)
+
+max_first_octet :: Cidr -> Octet
+max_first_octet cidr = first (max_octets cidr)
+
+max_second_octet :: Cidr -> Octet
+max_second_octet cidr = second (max_octets cidr)
+
+max_third_octet :: Cidr -> Octet
+max_third_octet cidr = third (max_octets cidr)
+
+max_fourth_octet :: Cidr -> Octet
+max_fourth_octet cidr = fourth (max_octets cidr)
+
+
+-- Returns the mask portion of a CIDR address. That is, everything
+-- after the trailing slash.
+maskbits_from_string :: String -> Maskbits
+maskbits_from_string s = read ((splitWith (`elem` "/") s) !! 1)
+
+
+-- Takes an IP address String in CIDR notation, and returns a list of
+-- its octets (converted to Int).
+octets_from_string :: String -> [Octet]
+octets_from_string s = map read (take 4 (splitWith (`elem` "./") s))
+
+
+from_string :: String -> Cidr
+from_string s = Cidr (octs !! 0) (octs !! 1) (octs !! 2) (octs !! 3) mbits
+ where
+ octs = octets_from_string s
+ mbits = maskbits_from_string s
+
+
+-- The base_two_to_base_ten function requires a way to determine
+-- whether or not the character it's currently parsing is valid. This
+-- should do it.
+is_binary_digit :: Char -> Bool
+is_binary_digit c =
+ if c `elem` ['0','1'] then
+ True
+ else
+ False
+
+
+-- Takes an Int, and returns its base-two representation as a String.
+base_two :: Int -> String
+base_two n = showIntAtBase 2 intToDigit n ""
+
+
+-- Takes a set of octets, and converts them to base-two
+-- individually. The results are then zero-padded on the left to 8
+-- characters, and concatenated together.
+octets_base_two :: Cidr -> String
+octets_base_two cidr =
+ s1 ++ s2 ++ s3 ++ s4
+ where
+ s1 = ((pad_left_to 8 '0') . base_two) (octet1 cidr)
+ s2 = ((pad_left_to 8 '0') . base_two) (octet2 cidr)
+ s3 = ((pad_left_to 8 '0') . base_two) (octet3 cidr)
+ s4 = ((pad_left_to 8 '0') . base_two) (octet4 cidr)
+
+
+base_two_octetlist_to_octetlist :: BaseTwoOctetList -> OctetList
+base_two_octetlist_to_octetlist b2ol =
+ (oct1, oct2, oct3, oct4)
+ where
+ oct1 = base_two_to_base_ten (first b2ol)
+ oct2 = base_two_to_base_ten (second b2ol)
+ oct3 = base_two_to_base_ten (third b2ol)
+ oct4 = base_two_to_base_ten (fourth b2ol)
+
+
+-- Convert a base-two String to an Int.
+base_two_to_base_ten :: String -> Int
+base_two_to_base_ten s =
+ if (length parsed) == 0 then
+ 0
+ else
+ fst (parsed !! 0)
+ where
+ parsed = readInt 2 is_binary_digit digitToInt s
+
+
+-- Returns the minimum address (as a base-two string) satisfying the
+-- given CIDR string.
+min_base_two_address :: Cidr -> String
+min_base_two_address cidr =
+ pad_right_to 32 '0' netpart
+ where
+ netpart = take (maskbits cidr) (octets_base_two cidr)
+
+
+-- Returns the maximum address (as a base-two string) satisfying the
+-- given CIDR string.
+max_base_two_address :: Cidr -> String
+max_base_two_address cidr =
+ pad_right_to 32 '1' netpart
+ where
+ netpart = take (maskbits cidr) (octets_base_two cidr)
+
+
+-- The octet components of min_base_two_address, as a base-two String.
+min_base_two_octets :: Cidr -> BaseTwoOctetList
+min_base_two_octets cidr =
+ (oct1, oct2, oct3, oct4)
+ where
+ addr = min_base_two_address cidr
+ oct1 = fst (splitAt 8 addr)
+ oct2 = fst (splitAt 8 (snd (splitAt 8 addr)))
+ oct3 = fst (splitAt 8 (snd (splitAt 16 addr)))
+ oct4 = snd (splitAt 24 addr)
+
+
+-- The octet components of max_base_two_address, as a base-two String.
+max_base_two_octets :: Cidr -> BaseTwoOctetList
+max_base_two_octets cidr =
+ (oct1, oct2, oct3, oct4)
+ where
+ addr = max_base_two_address cidr
+ oct1 = fst (splitAt 8 addr)
+ oct2 = fst (splitAt 8 (snd (splitAt 8 addr)))
+ oct3 = fst (splitAt 8 (snd (splitAt 16 addr)))
+ oct4 = snd (splitAt 24 addr)
+
+
+-- The octet components of min_base_two_address, as Ints.
+min_octets :: Cidr -> OctetList
+min_octets cidr = base_two_octetlist_to_octetlist (min_base_two_octets cidr)
+
+
+-- The octet components of max_base_two_address, as Ints.
+max_octets :: Cidr -> OctetList
+max_octets cidr = base_two_octetlist_to_octetlist (max_base_two_octets cidr)