+cidr_from_string :: String -> Cidr
+cidr_from_string s
+ | addr == IPv4Address.None = Cidr.None
+ | mbits == Maskbits.None = Cidr.None
+ | otherwise = Cidr addr mbits
+ where
+ addr = ipv4address_from_octets (oct1) (oct2) (oct3) (oct4)
+ oct1 = (octs !! 0)
+ oct2 = (octs !! 1)
+ oct3 = (octs !! 2)
+ oct4 = (octs !! 3)
+ octs = octets_from_cidr_string s
+ mbits = maskbits_from_cidr_string s
+
+
+
+min_host :: Cidr -> IPv4Address
+min_host Cidr.None = IPv4Address.None
+min_host (Cidr IPv4Address.None _) = IPv4Address.None
+min_host (Cidr _ Maskbits.None) = IPv4Address.None
+min_host (Cidr addr mask) = apply_mask addr mask B.Zero
+
+
+max_host :: Cidr -> IPv4Address
+max_host Cidr.None = IPv4Address.None
+max_host (Cidr IPv4Address.None _) = IPv4Address.None
+max_host (Cidr _ Maskbits.None) = IPv4Address.None
+max_host (Cidr addr mask) = apply_mask addr mask B.One
+
+
+min_octet1 :: Cidr -> Octet
+min_octet1 cidr = octet1 (min_host cidr)
+
+min_octet2 :: Cidr -> Octet
+min_octet2 cidr = octet2 (min_host cidr)
+
+min_octet3 :: Cidr -> Octet
+min_octet3 cidr = octet3 (min_host cidr)
+
+min_octet4 :: Cidr -> Octet
+min_octet4 cidr = octet4 (min_host cidr)
+
+max_octet1 :: Cidr -> Octet
+max_octet1 cidr = octet1 (max_host cidr)
+
+max_octet2 :: Cidr -> Octet
+max_octet2 cidr = octet2 (max_host cidr)
+
+max_octet3 :: Cidr -> Octet
+max_octet3 cidr = octet3 (max_host cidr)
+
+max_octet4 :: Cidr -> Octet
+max_octet4 cidr = octet4 (max_host cidr)
+
+
+
+-- Return true if the first argument (a CIDR range) contains the
+-- second (another CIDR range). There are a lot of ways we can be fed
+-- junk here. For lack of a better alternative, just return False when
+-- we are given nonsense.
+contains :: Cidr -> Cidr -> Bool
+contains Cidr.None _ = False
+contains _ Cidr.None = False
+contains (Cidr _ Maskbits.None) _ = False
+contains (Cidr IPv4Address.None _) _ = False
+contains _ (Cidr _ Maskbits.None) = False
+contains _ (Cidr IPv4Address.None _) = False
+
+-- If the number of bits in the network part of the first address is
+-- larger than the number of bits in the second, there is no way that
+-- the first range can contain the second. For, if the number of
+-- network bits is larger, then the number of host bits must be
+-- smaller, and if cidr1 has fewer hosts than cidr2, cidr1 most
+-- certainly does not contain cidr2.
+--
+-- On the other hand, if the first argument (cidr1) has fewer (or the
+-- same number of) network bits as the second, it can contain the
+-- second. In this case, we need to check that every host in cidr2 is
+-- contained in cidr1. If a host in cidr2 is contained in cidr1, then
+-- at least mbits1 of an address in cidr2 will match cidr1. For
+-- example,
+--
+-- cidr1 = 192.168.1.0/23, cidr2 = 192.168.1.100/24
+--
+-- Here, cidr2 contains all of 192.168.1.0 through
+-- 192.168.1.255. However, cidr1 contains BOTH 192.168.0.0 through
+-- 192.168.0.255 and 192.168.1.0 through 192.168.1.255. In essence,
+-- what we want to check is that cidr2 "begins with" something that
+-- cidr1 CAN begin with. Since cidr1 can begin with 192.168.1, and
+-- cidr2 DOES, cidr1 contains cidr2..
+--
+-- The way that we check this is to apply cidr1's mask to cidr2's
+-- address and see if the result is the same as cidr1's mask applied
+-- to cidr1's address.
+--
+contains (Cidr addr1 mbits1) (Cidr addr2 mbits2)
+ | mbits1 > mbits2 = False
+ | otherwise = addr1masked == addr2masked
+ where
+ addr1masked = apply_mask addr1 mbits1 B.Zero
+ addr2masked = apply_mask addr2 mbits1 B.Zero
+
+
+contains_proper :: Cidr -> Cidr -> Bool
+contains_proper cidr1 cidr2 =
+ (cidr1 `contains` cidr2) && (not (cidr2 `contains` cidr1))
+
+
+-- A CIDR range is redundant (with respect to the given list) if
+-- another CIDR range in that list properly contains it.
+redundant :: [Cidr] -> Cidr -> Bool
+redundant cidrlist cidr = any ((flip contains_proper) cidr) cidrlist
+
+
+-- First, we look at all possible pairs of cidrs, and combine the
+-- adjacent ones in to a new list. Then, we concatenate that list with
+-- the original one, and filter out all of the redundancies. If two
+-- adjacent Cidrs are combined into a larger one, they will be removed
+-- in the second step since the larger Cidr must contain the smaller
+-- two.
+--
+-- Once this is done, we see whether or not the result is different
+-- than the argument that was passed in. If nothing changed, we're
+-- done and return the list that was passed to us. However, if
+-- something changed, we recurse and try to combine the list again.
+combine_all :: [Cidr] -> [Cidr]
+combine_all cidrs
+ | cidrs == (combine_contained unique_cidrs) = cidrs
+ | otherwise = combine_all (combine_contained unique_cidrs)
+ where
+ unique_cidrs = nubBy equivalent valid_cidr_combinations
+ valid_cidr_combinations = filter (/= Cidr.None) cidr_combinations
+ cidr_combinations =
+ cidrs ++ [ (combine_adjacent x y) | x <- cidrs, y <- cidrs ]