src/Cidr.hs

   1 module Cidr
   2 ( Cidr(..),
   3   cidr_from_string,
   4   cidr_tests,
   5   combine_all,
   6   contains,
   7   contains_proper,
   8   max_octet1,
   9   max_octet2,
  10   max_octet3,
  11   max_octet4,
  12   min_octet1,
  13   min_octet2,
  14   min_octet3,
  15   min_octet4,
  16   prop_all_cidrs_contain_themselves,
  17   prop_contains_proper_intransitive
  18 ) where
  19
  20 import Data.List (nubBy)
  21 import Test.HUnit
  22 import Test.QuickCheck
  23
  24 import qualified Bit as B
  25 import IPv4Address
  26 import ListUtils
  27 import Maskable
  28 import Maskbits
  29 import Octet
  30
  31
  32 data Cidr = None | Cidr { ipv4address :: IPv4Address,
  33                           maskbits :: Maskbits }
  34
  35
  36
  37 instance Show Cidr where
  38     show Cidr.None = "None"
  39     show cidr = (show (ipv4address cidr)) ++ "/" ++ (show (maskbits cidr))
  40
  41
  42 instance Arbitrary Cidr where
  43     arbitrary = do
  44       ipv4 <- arbitrary :: Gen IPv4Address
  45       mask <- arbitrary :: Gen Maskbits
  46       return (Cidr ipv4 mask)
  47
  48     coarbitrary _ = variant 0
  49
  50 instance Eq Cidr where
  51   cidr1 == cidr2 = (cidr1 `equivalent` cidr2)
  52
  53
  54 -- Two CIDR ranges are equivalent if they have the same network bits
  55 -- and the masks are the same.
  56 equivalent :: Cidr -> Cidr -> Bool
  57 equivalent Cidr.None Cidr.None = True
  58 equivalent Cidr.None _ = False
  59 equivalent _ Cidr.None = False
  60 equivalent (Cidr addr1 mbits1) (Cidr addr2 mbits2) =
  61     (mbits1 == mbits2) && ((apply_mask addr1 mbits1 B.Zero) == (apply_mask addr2 mbits2 B.Zero))
  62
  63 -- Returns the mask portion of a CIDR address. That is, everything
  64 -- after the trailing slash.
  65 maskbits_from_cidr_string :: String -> Maskbits
  66 maskbits_from_cidr_string s
  67     | length partlist == 2 = maskbits_from_string (partlist !! 1)
  68     | otherwise = Maskbits.None
  69       where
  70         partlist = (splitWith (`elem` "/") s)
  71
  72
  73 -- Takes an IP address String in CIDR notation, and returns a list of
  74 -- its octets (as Ints).
  75 octets_from_cidr_string :: String -> [Octet]
  76 octets_from_cidr_string s =
  77     map octet_from_string (take 4 (splitWith (`elem` "./") s))
  78
  79
  80 cidr_from_string :: String -> Cidr
  81 cidr_from_string s
  82     | addr  == IPv4Address.None = Cidr.None
  83     | mbits == Maskbits.None    = Cidr.None
  84     | otherwise = Cidr addr mbits
  85                where
  86                  addr = ipv4address_from_octets (oct1) (oct2) (oct3) (oct4)
  87                  oct1 = (octs !! 0)
  88                  oct2 = (octs !! 1)
  89                  oct3 = (octs !! 2)
  90                  oct4 = (octs !! 3)
  91                  octs  = octets_from_cidr_string s
  92                  mbits = maskbits_from_cidr_string s
  93
  94
  95
  96 min_host :: Cidr -> IPv4Address
  97 min_host Cidr.None                 = IPv4Address.None
  98 min_host (Cidr IPv4Address.None _) = IPv4Address.None
  99 min_host (Cidr _ Maskbits.None)    = IPv4Address.None
 100 min_host (Cidr addr mask) = apply_mask addr mask B.Zero
 101
 102
 103 max_host :: Cidr -> IPv4Address
 104 max_host Cidr.None                 = IPv4Address.None
 105 max_host (Cidr IPv4Address.None _) = IPv4Address.None
 106 max_host (Cidr _ Maskbits.None)    = IPv4Address.None
 107 max_host (Cidr addr mask) = apply_mask addr mask B.One
 108
 109
 110 min_octet1 :: Cidr -> Octet
 111 min_octet1 cidr = octet1 (min_host cidr)
 112
 113 min_octet2 :: Cidr -> Octet
 114 min_octet2 cidr = octet2 (min_host cidr)
 115
 116 min_octet3 :: Cidr -> Octet
 117 min_octet3 cidr = octet3 (min_host cidr)
 118
 119 min_octet4 :: Cidr -> Octet
 120 min_octet4 cidr = octet4 (min_host cidr)
 121
 122 max_octet1 :: Cidr -> Octet
 123 max_octet1 cidr = octet1 (max_host cidr)
 124
 125 max_octet2 :: Cidr -> Octet
 126 max_octet2 cidr = octet2 (max_host cidr)
 127
 128 max_octet3 :: Cidr -> Octet
 129 max_octet3 cidr = octet3 (max_host cidr)
 130
 131 max_octet4 :: Cidr -> Octet
 132 max_octet4 cidr = octet4 (max_host cidr)
 133
 134
 135
 136 -- Return true if the first argument (a CIDR range) contains the
 137 -- second (another CIDR range). There are a lot of ways we can be fed
 138 -- junk here. For lack of a better alternative, just return False when
 139 -- we are given nonsense.
 140 contains :: Cidr -> Cidr -> Bool
 141 contains Cidr.None _ = False
 142 contains _ Cidr.None = False
 143 contains (Cidr _ Maskbits.None) _    = False
 144 contains (Cidr IPv4Address.None _) _ = False
 145 contains _ (Cidr _ Maskbits.None)    = False
 146 contains _ (Cidr IPv4Address.None _) = False
 147
 148 -- If the number of bits in the network part of the first address is
 149 -- larger than the number of bits in the second, there is no way that
 150 -- the first range can contain the second. For, if the number of
 151 -- network bits is larger, then the number of host bits must be
 152 -- smaller, and if cidr1 has fewer hosts than cidr2, cidr1 most
 153 -- certainly does not contain cidr2.
 154 --
 155 -- On the other hand, if the first argument (cidr1) has fewer (or the
 156 -- same number of) network bits as the second, it can contain the
 157 -- second. In this case, we need to check that every host in cidr2 is
 158 -- contained in cidr1. If a host in cidr2 is contained in cidr1, then
 159 -- at least mbits1 of an address in cidr2 will match cidr1. For
 160 -- example,
 161 --
 162 -- cidr1 = 192.168.1.0/23, cidr2 = 192.168.1.100/24
 163 --
 164 -- Here, cidr2 contains all of 192.168.1.0 through
 165 -- 192.168.1.255. However, cidr1 contains BOTH 192.168.0.0 through
 166 -- 192.168.0.255 and 192.168.1.0 through 192.168.1.255. In essence,
 167 -- what we want to check is that cidr2 "begins with" something that
 168 -- cidr1 CAN begin with. Since cidr1 can begin with 192.168.1, and
 169 -- cidr2 DOES, cidr1 contains cidr2..
 170 --
 171 -- The way that we check this is to apply cidr1's mask to cidr2's
 172 -- address and see if the result is the same as cidr1's mask applied
 173 -- to cidr1's address.
 174 --
 175 contains (Cidr addr1 mbits1) (Cidr addr2 mbits2)
 176     | mbits1 > mbits2 = False
 177     | otherwise = addr1masked == addr2masked
 178     where
 179       addr1masked = apply_mask addr1 mbits1 B.Zero
 180       addr2masked = apply_mask addr2 mbits1 B.Zero
 181
 182
 183 contains_proper :: Cidr -> Cidr -> Bool
 184 contains_proper cidr1 cidr2 =
 185     (cidr1 `contains` cidr2) && (not (cidr2 `contains` cidr1))
 186
 187
 188 -- A CIDR range is redundant (with respect to the given list) if
 189 -- another CIDR range in that list properly contains it.
 190 redundant :: [Cidr] -> Cidr -> Bool
 191 redundant cidrlist cidr = any ((flip contains_proper) cidr) cidrlist
 192
 193
 194 -- First, we look at all possible pairs of cidrs, and combine the
 195 -- adjacent ones in to a new list. Then, we concatenate that list with
 196 -- the original one, and filter out all of the redundancies. If two
 197 -- adjacent Cidrs are combined into a larger one, they will be removed
 198 -- in the second step since the larger Cidr must contain the smaller
 199 -- two.
 200 --
 201 -- Once this is done, we see whether or not the result is different
 202 -- than the argument that was passed in. If nothing changed, we're
 203 -- done and return the list that was passed to us. However, if
 204 -- something changed, we recurse and try to combine the list again.
 205 combine_all :: [Cidr] -> [Cidr]
 206 combine_all cidrs
 207   | cidrs == (combine_contained unique_cidrs) = cidrs
 208   | otherwise = combine_all (combine_contained unique_cidrs)
 209     where
 210       unique_cidrs = nubBy equivalent valid_cidr_combinations
 211       valid_cidr_combinations = filter (/= Cidr.None) cidr_combinations
 212       cidr_combinations =
 213           cidrs ++ [ (combine_adjacent x y) | x <- cidrs, y <- cidrs ]
 214
 215
 216 -- Take a list of CIDR ranges and filter out all of the ones that are
 217 -- contained entirelt within some other range in the list.
 218 combine_contained :: [Cidr] -> [Cidr]
 219 combine_contained cidrs =
 220     filter (not . (redundant cidrs)) cidrs
 221
 222
 223 -- If the two Cidrs are not adjacent, return Cidr.None. Otherwise,
 224 -- decrement the maskbits of cidr1 and return that; it will contain
 225 -- both cidr1 and cidr2.
 226 combine_adjacent :: Cidr -> Cidr -> Cidr
 227 combine_adjacent cidr1 cidr2
 228   | not (adjacent cidr1 cidr2) = Cidr.None
 229   | (maskbits cidr1 == Zero) = Cidr.None
 230   | otherwise = cidr1 { maskbits = decrement (maskbits cidr1) }
 231
 232
 233
 234 -- Determine whether or not two CIDR ranges are adjacent. If two
 235 -- ranges lie consecutively within the IP space, they can be
 236 -- combined. For example, 10.1.0.0/24 and 10.0.1.0/24 are adjacent,
 237 -- and can be combined in to 10.1.0.0/23.
 238 adjacent :: Cidr -> Cidr -> Bool
 239 adjacent Cidr.None _ = False
 240 adjacent _ Cidr.None = False
 241 adjacent cidr1 cidr2
 242   | mbits1 /= mbits2 = False
 243   | mbits1 == Maskbits.Zero = False -- They're equal.
 244   | otherwise = (mbits1 == (most_sig_bit_different addr1 addr2))
 245   where
 246     addr1 = ipv4address cidr1
 247     addr2 = ipv4address cidr2
 248     mbits1 = maskbits cidr1
 249     mbits2 = maskbits cidr2
 250
 251
 252
 253
 254
 255 -- HUnit Tests
 256
 257 test_min_host1 :: Test
 258 test_min_host1 =
 259     TestCase $ assertEqual "The minimum host in 10.0.0.0/24 is 10.0.0.0" expected actual
 260     where
 261       actual = show $ min_host (cidr_from_string "10.0.0.0/24")
 262       expected = "10.0.0.0"
 263
 264
 265 test_max_host1 :: Test
 266 test_max_host1 =
 267     TestCase $ assertEqual "The maximum host in 10.0.0.0/24 is 10.0.0.255" expected actual
 268     where
 269       actual = show $ max_host (cidr_from_string "10.0.0.0/24")
 270       expected = "10.0.0.255"
 271
 272
 273 test_equality1 :: Test
 274 test_equality1 =
 275     TestCase $ assertEqual "10.1.1.0/23 equals itself" True (cidr1 == cidr1)
 276     where
 277       cidr1 = cidr_from_string "10.1.1.0/23"
 278
 279
 280 test_contains1 :: Test
 281 test_contains1 =
 282     TestCase $ assertEqual "10.1.1.0/23 contains 10.1.1.0/24" True (cidr1 `contains` cidr2)
 283     where
 284       cidr1 = cidr_from_string "10.1.1.0/23"
 285       cidr2 = cidr_from_string "10.1.1.0/24"
 286
 287
 288 test_contains2 :: Test
 289 test_contains2 =
 290     TestCase $ assertEqual "10.1.1.0/23 contains itself" True (cidr1 `contains` cidr1)
 291     where
 292       cidr1 = cidr_from_string "10.1.1.0/23"
 293
 294
 295 test_contains_proper1 :: Test
 296 test_contains_proper1 =
 297     TestCase $ assertEqual "10.1.1.0/23 contains 10.1.1.0/24 properly" True (cidr1 `contains_proper` cidr2)
 298     where
 299       cidr1 = cidr_from_string "10.1.1.0/23"
 300       cidr2 = cidr_from_string "10.1.1.0/24"
 301
 302
 303 test_contains_proper2 :: Test
 304 test_contains_proper2 =
 305     TestCase $ assertEqual "10.1.1.0/23 does not contain itself properly" False (cidr1 `contains_proper` cidr1)
 306     where
 307       cidr1 = cidr_from_string "10.1.1.0/23"
 308
 309
 310 test_adjacent1 :: Test
 311 test_adjacent1 =
 312     TestCase $ assertEqual "10.1.0.0/24 is adjacent to 10.1.1.0/24" True (cidr1 `adjacent` cidr2)
 313     where
 314       cidr1 = cidr_from_string "10.1.0.0/24"
 315       cidr2 = cidr_from_string "10.1.1.0/24"
 316
 317
 318 test_adjacent2 :: Test
 319 test_adjacent2 =
 320     TestCase $ assertEqual "10.1.0.0/23 is not adjacent to 10.1.0.0/24" False (cidr1 `adjacent` cidr2)
 321     where
 322       cidr1 = cidr_from_string "10.1.0.0/23"
 323       cidr2 = cidr_from_string "10.1.0.0/24"
 324
 325
 326 test_adjacent3 :: Test
 327 test_adjacent3 =
 328     TestCase $ assertEqual "10.1.0.0/24 is not adjacent to 10.2.5.0/24" False (cidr1 `adjacent` cidr2)
 329     where
 330       cidr1 = cidr_from_string "10.1.0.0/24"
 331       cidr2 = cidr_from_string "10.2.5.0/24"
 332
 333
 334 test_adjacent4 :: Test
 335 test_adjacent4 =
 336     TestCase $ assertEqual "10.1.1.0/24 is not adjacent to 10.1.2.0/24" False (cidr1 `adjacent` cidr2)
 337     where
 338       cidr1 = cidr_from_string "10.1.1.0/24"
 339       cidr2 = cidr_from_string "10.1.2.0/24"
 340
 341
 342 test_combine_contained1 :: Test
 343 test_combine_contained1 =
 344     TestCase $ assertEqual "10.0.0.0/8, 10.1.0.0/16, and 10.1.1.0/24 combine to 10.0.0.0/8" expected_cidrs (combine_contained test_cidrs)
 345     where
 346       cidr1 = cidr_from_string "10.0.0.0/8"
 347       cidr2 = cidr_from_string "10.1.0.0/16"
 348       cidr3 = cidr_from_string "10.1.1.0/24"
 349       expected_cidrs = [cidr1]
 350       test_cidrs = [cidr1, cidr2, cidr3]
 351
 352
 353 test_combine_contained2 :: Test
 354 test_combine_contained2 =
 355     TestCase $ assertEqual "192.168.3.0/23 does not contain 192.168.1.0/24" [cidr1, cidr2] (combine_contained [cidr1, cidr2])
 356     where
 357       cidr1 = cidr_from_string "192.168.3.0/23"
 358       cidr2 = cidr_from_string "192.168.1.0/24"
 359
 360
 361 test_combine_all1 :: Test
 362 test_combine_all1 =
 363     TestCase $ assertEqual "10.0.0.0/24 is adjacent to 10.0.1.0/24 and 10.0.3.0/23 contains 10.0.2.0/24" expected_cidrs (combine_all test_cidrs)
 364     where
 365       cidr1 = cidr_from_string "10.0.0.0/24"
 366       cidr2 = cidr_from_string "10.0.1.0/24"
 367       cidr3 = cidr_from_string "10.0.2.0/24"
 368       cidr4 = cidr_from_string "10.0.3.0/23"
 369       cidr5 = cidr_from_string "10.0.0.0/23"
 370       expected_cidrs = [cidr_from_string "10.0.0.0/22"]
 371       test_cidrs = [cidr1, cidr2, cidr3, cidr4, cidr5]
 372
 373
 374 test_combine_all2 :: Test
 375 test_combine_all2 =
 376     TestCase $ assertEqual "127.0.0.1/32 combines with itself recursively" expected_cidrs (combine_all test_cidrs)
 377     where
 378       cidr1 = cidr_from_string "127.0.0.1/32"
 379       expected_cidrs = [cidr1]
 380       test_cidrs = [cidr1, cidr1, cidr1, cidr1, cidr1]
 381
 382
 383 test_combine_all3 :: Test
 384 test_combine_all3 =
 385     TestCase $ assertEqual "10.0.0.16, 10.0.0.17, 10.0.0.18, and 10.0.0.19 get combined into 10.0.0.16/30" expected_cidrs (combine_all test_cidrs)
 386     where
 387       cidr1 = cidr_from_string "10.0.0.16/32"
 388       cidr2 = cidr_from_string "10.0.0.17/32"
 389       cidr3 = cidr_from_string "10.0.0.18/32"
 390       cidr4 = cidr_from_string "10.0.0.19/32"
 391       expected_cidrs = [cidr_from_string "10.0.0.16/30"]
 392       test_cidrs = [cidr1, cidr2, cidr3, cidr4]
 393
 394
 395 cidr_tests :: [Test]
 396 cidr_tests = [ test_min_host1,
 397                test_max_host1,
 398                test_equality1,
 399                test_contains1,
 400                test_contains2,
 401                test_contains_proper1,
 402                test_contains_proper2,
 403                test_adjacent1,
 404                test_adjacent2,
 405                test_adjacent3,
 406                test_adjacent4,
 407                test_combine_contained1,
 408                test_combine_contained2,
 409                test_combine_all1,
 410                test_combine_all2,
 411                test_combine_all3
 412              ]
 413
 414
 415 -- QuickCheck Tests
 416 prop_all_cidrs_contain_themselves :: Cidr -> Bool
 417 prop_all_cidrs_contain_themselves cidr1 = cidr1 `contains` cidr1
 418
 419
 420 -- If cidr1 properly contains cidr2, then by definition cidr2
 421 -- does not properly contain cidr1.
 422 prop_contains_proper_intransitive :: Cidr -> Cidr -> Property
 423 prop_contains_proper_intransitive cidr1 cidr2 =
 424     (cidr1 `contains_proper` cidr2) ==>
 425       (not (cidr2 `contains_proper` cidr1))