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