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 Data.Maybe (catMaybes, fromJust)
  22 import Test.HUnit
  23 import Test.QuickCheck
  24
  25 import qualified Bit as B
  26 import IPv4Address
  27 import ListUtils
  28 import Maskable
  29 import Maskbits
  30 import Octet
  31
  32
  33 data Cidr = Cidr { ipv4address :: IPv4Address,
  34                    maskbits :: Maskbits }
  35
  36
  37
  38 instance Show Cidr where
  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
  49 instance Eq Cidr where
  50   cidr1 == cidr2 = (cidr1 `equivalent` cidr2)
  51
  52
  53 -- Two CIDR ranges are equivalent if they have the same network bits
  54 -- and the masks are the same.
  55 equivalent :: Cidr -> Cidr -> Bool
  56 equivalent (Cidr addr1 mbits1) (Cidr addr2 mbits2) =
  57     (mbits1 == mbits2) && ((apply_mask addr1 mbits1 B.Zero) == (apply_mask addr2 mbits2 B.Zero))
  58
  59 -- Returns the mask portion of a CIDR address. That is, everything
  60 -- after the trailing slash.
  61 maskbits_from_cidr_string :: String -> Maybe Maskbits
  62 maskbits_from_cidr_string s
  63   | length partlist == 2 = maskbits_from_string (partlist !! 1)
  64   | otherwise = Nothing
  65     where
  66       partlist = (splitWith (`elem` "/") s)
  67
  68
  69 -- | Takes an IP address String in CIDR notation, and returns a list
  70 --   of its octets (as Ints).
  71 octets_from_cidr_string :: String -> [Octet]
  72 octets_from_cidr_string s =
  73   catMaybes $ map octet_from_string (take 4 (splitWith (`elem` "./") s))
  74
  75
  76 -- | Return Nothing if we can't parse both maskbits and octets from
  77 --   the string.
  78 cidr_from_string :: String -> Maybe Cidr
  79 cidr_from_string s =
  80   case (octets_from_cidr_string s) of
  81     [oct1, oct2, oct3, oct4] ->
  82       case (maskbits_from_cidr_string s) of
  83         Just mbits ->
  84           Just $ Cidr (IPv4Address oct1 oct2 oct3 oct4) mbits
  85         _ -> Nothing
  86     _ -> Nothing
  87
  88
  89
  90 min_host :: Cidr -> IPv4Address
  91 min_host (Cidr addr mask) = apply_mask addr mask B.Zero
  92
  93
  94 max_host :: Cidr -> IPv4Address
  95 max_host (Cidr addr mask) = apply_mask addr mask B.One
  96
  97
  98 min_octet1 :: Cidr -> Octet
  99 min_octet1 cidr = octet1 (min_host cidr)
 100
 101 min_octet2 :: Cidr -> Octet
 102 min_octet2 cidr = octet2 (min_host cidr)
 103
 104 min_octet3 :: Cidr -> Octet
 105 min_octet3 cidr = octet3 (min_host cidr)
 106
 107 min_octet4 :: Cidr -> Octet
 108 min_octet4 cidr = octet4 (min_host cidr)
 109
 110 max_octet1 :: Cidr -> Octet
 111 max_octet1 cidr = octet1 (max_host cidr)
 112
 113 max_octet2 :: Cidr -> Octet
 114 max_octet2 cidr = octet2 (max_host cidr)
 115
 116 max_octet3 :: Cidr -> Octet
 117 max_octet3 cidr = octet3 (max_host cidr)
 118
 119 max_octet4 :: Cidr -> Octet
 120 max_octet4 cidr = octet4 (max_host cidr)
 121
 122
 123
 124 -- | Return true if the first argument (a CIDR range) contains the
 125 --   second (another CIDR range). There are a lot of ways we can be
 126 --   fed junk here. For lack of a better alternative, just return
 127 --   False when we are given nonsense.
 128 --
 129 --   If the number of bits in the network part of the first address is
 130 --   larger than the number of bits in the second, there is no way
 131 --   that the first range can contain the second. For, if the number
 132 --   of network bits is larger, then the number of host bits must be
 133 --   smaller, and if cidr1 has fewer hosts than cidr2, cidr1 most
 134 --   certainly does not contain cidr2.
 135 --
 136 --   On the other hand, if the first argument (cidr1) has fewer (or
 137 --   the same number of) network bits as the second, it can contain
 138 --   the second. In this case, we need to check that every host in
 139 --   cidr2 is contained in cidr1. If a host in cidr2 is contained in
 140 --   cidr1, then at least mbits1 of an address in cidr2 will match
 141 --   cidr1. For example,
 142 --
 143 --   cidr1 = 192.168.1.0/23, cidr2 = 192.168.1.100/24
 144 --
 145 --   Here, cidr2 contains all of 192.168.1.0 through
 146 --   192.168.1.255. However, cidr1 contains BOTH 192.168.0.0 through
 147 --   192.168.0.255 and 192.168.1.0 through 192.168.1.255. In essence,
 148 --   what we want to check is that cidr2 "begins with" something that
 149 --   cidr1 CAN begin with. Since cidr1 can begin with 192.168.1, and
 150 --   cidr2 DOES, cidr1 contains cidr2..
 151 --
 152 --   The way that we check this is to apply cidr1's mask to cidr2's
 153 --   address and see if the result is the same as cidr1's mask applied
 154 --   to cidr1's address.
 155 --
 156 contains :: Cidr -> Cidr -> Bool
 157 contains (Cidr addr1 mbits1) (Cidr addr2 mbits2)
 158   | mbits1 > mbits2 = False
 159   | otherwise = addr1masked == addr2masked
 160   where
 161     addr1masked = apply_mask addr1 mbits1 B.Zero
 162     addr2masked = apply_mask addr2 mbits1 B.Zero
 163
 164
 165 contains_proper :: Cidr -> Cidr -> Bool
 166 contains_proper cidr1 cidr2 =
 167     (cidr1 `contains` cidr2) && (not (cidr2 `contains` cidr1))
 168
 169
 170 -- | A CIDR range is redundant (with respect to the given list) if
 171 --   another CIDR range in that list properly contains it.
 172 redundant :: [Cidr] -> Cidr -> Bool
 173 redundant cidrlist cidr = any ((flip contains_proper) cidr) cidrlist
 174
 175
 176 -- | First, we look at all possible pairs of cidrs, and combine the
 177 --   adjacent ones in to a new list. Then, we concatenate that list
 178 --   with the original one, and filter out all of the redundancies. If
 179 --   two adjacent Cidrs are combined into a larger one, they will be
 180 --   removed in the second step since the larger Cidr must contain the
 181 --   smaller two.
 182 --
 183 --   Once this is done, we see whether or not the result is different
 184 --   than the argument that was passed in. If nothing changed, we're
 185 --   done and return the list that was passed to us. However, if
 186 --   something changed, we recurse and try to combine the list again.
 187 combine_all :: [Cidr] -> [Cidr]
 188 combine_all cidrs
 189   | cidrs == (combine_contained unique_cidrs) = cidrs
 190   | otherwise = combine_all (combine_contained unique_cidrs)
 191     where
 192       unique_cidrs = nubBy equivalent cidr_combinations
 193       cidr_combinations =
 194         cidrs ++ (catMaybes [ (combine_adjacent x y) | x <- cidrs, y <- cidrs ])
 195
 196
 197 -- | Take a list of CIDR ranges and filter out all of the ones that
 198 --   are contained entirelt within some other range in the list.
 199 combine_contained :: [Cidr] -> [Cidr]
 200 combine_contained cidrs =
 201   filter (not . (redundant cidrs)) cidrs
 202
 203
 204 -- | If the two Cidrs are not adjacent, return Cidr.None. Otherwise,
 205 --   decrement the maskbits of cidr1 and return that; it will contain
 206 --   both cidr1 and cidr2.
 207 combine_adjacent :: Cidr -> Cidr -> Maybe Cidr
 208 combine_adjacent cidr1 cidr2
 209   | not (adjacent cidr1 cidr2) = Nothing
 210   | (maskbits cidr1 == Zero) = Nothing
 211   | otherwise = Just $ cidr1 { maskbits = decrement (maskbits cidr1) }
 212
 213
 214
 215 -- | Determine whether or not two CIDR ranges are adjacent. If two
 216 --   ranges lie consecutively within the IP space, they can be
 217 --   combined. For example, 10.1.0.0/24 and 10.0.1.0/24 are adjacent,
 218 --   and can be combined in to 10.1.0.0/23.
 219 adjacent :: Cidr -> Cidr -> Bool
 220 adjacent cidr1 cidr2
 221   | mbits1 /= mbits2 = False
 222   | mbits1 == Maskbits.Zero = False -- They're equal.
 223   | otherwise = (mbits1 == (most_sig_bit_different addr1 addr2))
 224   where
 225     addr1 = ipv4address cidr1
 226     addr2 = ipv4address cidr2
 227     mbits1 = maskbits cidr1
 228     mbits2 = maskbits cidr2
 229
 230
 231
 232
 233
 234 -- HUnit Tests
 235
 236 test_min_host1 :: Test
 237 test_min_host1 =
 238   TestCase $ assertEqual "The minimum host in 10.0.0.0/24 is 10.0.0.0"
 239              expected
 240              actual
 241   where
 242     actual = show $ min_host (fromJust $ cidr_from_string "10.0.0.0/24")
 243     expected = "10.0.0.0"
 244
 245
 246 test_max_host1 :: Test
 247 test_max_host1 =
 248   TestCase $ assertEqual "The maximum host in 10.0.0.0/24 is 10.0.0.255"
 249              expected
 250              actual
 251   where
 252     actual = show $ max_host (fromJust $ cidr_from_string "10.0.0.0/24")
 253     expected = "10.0.0.255"
 254
 255
 256 test_equality1 :: Test
 257 test_equality1 =
 258   TestCase $
 259     assertEqual
 260     "10.1.1.0/23 equals itself"
 261     True
 262     (cidr1 == cidr1)
 263   where
 264     cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
 265
 266
 267 test_contains1 :: Test
 268 test_contains1 =
 269   TestCase $
 270     assertEqual
 271     "10.1.1.0/23 contains 10.1.1.0/24"
 272     True
 273     (cidr1 `contains` cidr2)
 274   where
 275     cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
 276     cidr2 = fromJust $ cidr_from_string "10.1.1.0/24"
 277
 278
 279 test_contains2 :: Test
 280 test_contains2 =
 281   TestCase $
 282     assertEqual
 283     "10.1.1.0/23 contains itself"
 284     True
 285     (cidr1 `contains` cidr1)
 286   where
 287     cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
 288
 289
 290 test_contains_proper1 :: Test
 291 test_contains_proper1 =
 292   TestCase $
 293     assertEqual
 294     "10.1.1.0/23 contains 10.1.1.0/24 properly"
 295     True
 296     (cidr1 `contains_proper` cidr2)
 297   where
 298     cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
 299     cidr2 = fromJust $ cidr_from_string "10.1.1.0/24"
 300
 301
 302 test_contains_proper2 :: Test
 303 test_contains_proper2 =
 304   TestCase $
 305     assertEqual
 306     "10.1.1.0/23 does not contain itself properly"
 307     False
 308     (cidr1 `contains_proper` cidr1)
 309   where
 310     cidr1 = fromJust $ cidr_from_string "10.1.1.0/23"
 311
 312
 313 test_adjacent1 :: Test
 314 test_adjacent1 =
 315   TestCase $
 316     assertEqual
 317     "10.1.0.0/24 is adjacent to 10.1.1.0/24"
 318     True
 319     (cidr1 `adjacent` cidr2)
 320   where
 321     cidr1 = fromJust $ cidr_from_string "10.1.0.0/24"
 322     cidr2 = fromJust $ cidr_from_string "10.1.1.0/24"
 323
 324
 325 test_adjacent2 :: Test
 326 test_adjacent2 =
 327   TestCase $
 328     assertEqual
 329     "10.1.0.0/23 is not adjacent to 10.1.0.0/24"
 330     False
 331     (cidr1 `adjacent` cidr2)
 332   where
 333     cidr1 = fromJust $ cidr_from_string "10.1.0.0/23"
 334     cidr2 = fromJust $ cidr_from_string "10.1.0.0/24"
 335
 336
 337 test_adjacent3 :: Test
 338 test_adjacent3 =
 339   TestCase $
 340     assertEqual
 341     "10.1.0.0/24 is not adjacent to 10.2.5.0/24"
 342     False
 343     (cidr1 `adjacent` cidr2)
 344   where
 345     cidr1 = fromJust $ cidr_from_string "10.1.0.0/24"
 346     cidr2 = fromJust $ cidr_from_string "10.2.5.0/24"
 347
 348
 349 test_adjacent4 :: Test
 350 test_adjacent4 =
 351   TestCase $
 352     assertEqual
 353     "10.1.1.0/24 is not adjacent to 10.1.2.0/24"
 354     False
 355     (cidr1 `adjacent` cidr2)
 356   where
 357     cidr1 = fromJust $ cidr_from_string "10.1.1.0/24"
 358     cidr2 = fromJust $ cidr_from_string "10.1.2.0/24"
 359
 360
 361 test_combine_contained1 :: Test
 362 test_combine_contained1 =
 363   TestCase $
 364     assertEqual
 365     "10.0.0.0/8, 10.1.0.0/16, and 10.1.1.0/24 combine to 10.0.0.0/8"
 366     expected_cidrs
 367     (combine_contained test_cidrs)
 368   where
 369     cidr1 = fromJust $ cidr_from_string "10.0.0.0/8"
 370     cidr2 = fromJust $ cidr_from_string "10.1.0.0/16"
 371     cidr3 = fromJust $ cidr_from_string "10.1.1.0/24"
 372     expected_cidrs = [cidr1]
 373     test_cidrs = [cidr1, cidr2, cidr3]
 374
 375
 376 test_combine_contained2 :: Test
 377 test_combine_contained2 =
 378   TestCase $
 379     assertEqual
 380     "192.168.3.0/23 does not contain 192.168.1.0/24"
 381     [cidr1, cidr2]
 382     (combine_contained [cidr1, cidr2])
 383   where
 384     cidr1 = fromJust $ cidr_from_string "192.168.3.0/23"
 385     cidr2 = fromJust $ cidr_from_string "192.168.1.0/24"
 386
 387
 388 test_combine_all1 :: Test
 389 test_combine_all1 =
 390   TestCase $
 391     assertEqual
 392     "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"
 393     expected_cidrs
 394     (combine_all test_cidrs)
 395   where
 396     cidr1 = fromJust $ cidr_from_string "10.0.0.0/24"
 397     cidr2 = fromJust $ cidr_from_string "10.0.1.0/24"
 398     cidr3 = fromJust $ cidr_from_string "10.0.2.0/24"
 399     cidr4 = fromJust $ cidr_from_string "10.0.3.0/23"
 400     cidr5 = fromJust $ cidr_from_string "10.0.0.0/23"
 401     expected_cidrs = [fromJust $ cidr_from_string "10.0.0.0/22"]
 402     test_cidrs = [cidr1, cidr2, cidr3, cidr4, cidr5]
 403
 404
 405 test_combine_all2 :: Test
 406 test_combine_all2 =
 407     TestCase $
 408       assertEqual
 409       "127.0.0.1/32 combines with itself recursively"
 410       expected_cidrs
 411       (combine_all test_cidrs)
 412     where
 413       cidr1 = fromJust $ cidr_from_string "127.0.0.1/32"
 414       expected_cidrs = [cidr1]
 415       test_cidrs = [cidr1, cidr1, cidr1, cidr1, cidr1]
 416
 417
 418 test_combine_all3 :: Test
 419 test_combine_all3 =
 420   TestCase $
 421     assertEqual
 422     "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"
 423     expected_cidrs
 424     (combine_all test_cidrs)
 425   where
 426     cidr1 = fromJust $ cidr_from_string "10.0.0.16/32"
 427     cidr2 = fromJust $ cidr_from_string "10.0.0.17/32"
 428     cidr3 = fromJust $ cidr_from_string "10.0.0.18/32"
 429     cidr4 = fromJust $ cidr_from_string "10.0.0.19/32"
 430     expected_cidrs = [fromJust $ cidr_from_string "10.0.0.16/30"]
 431     test_cidrs = [cidr1, cidr2, cidr3, cidr4]
 432
 433
 434 cidr_tests :: [Test]
 435 cidr_tests = [ test_min_host1,
 436                test_max_host1,
 437                test_equality1,
 438                test_contains1,
 439                test_contains2,
 440                test_contains_proper1,
 441                test_contains_proper2,
 442                test_adjacent1,
 443                test_adjacent2,
 444                test_adjacent3,
 445                test_adjacent4,
 446                test_combine_contained1,
 447                test_combine_contained2,
 448                test_combine_all1,
 449                test_combine_all2,
 450                test_combine_all3
 451              ]
 452
 453
 454 -- QuickCheck Tests
 455 prop_all_cidrs_contain_themselves :: Cidr -> Bool
 456 prop_all_cidrs_contain_themselves cidr1 = cidr1 `contains` cidr1
 457
 458
 459 -- If cidr1 properly contains cidr2, then by definition cidr2
 460 -- does not properly contain cidr1.
 461 prop_contains_proper_intransitive :: Cidr -> Cidr -> Property
 462 prop_contains_proper_intransitive cidr1 cidr2 =
 463     (cidr1 `contains_proper` cidr2) ==>
 464       (not (cidr2 `contains_proper` cidr1))