X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FIPv4Address.hs;h=4399b05f3ecb1728eca31be6eae5e833a23a3b5b;hb=ac5698aeedccb731b4d9494b19efaf62dc70791a;hp=d262a5c0537ea47092d0255ab417b6516d1cdab8;hpb=eee156f562f9c1c1194a67cef12f146304d88ce9;p=hath.git diff --git a/src/IPv4Address.hs b/src/IPv4Address.hs index d262a5c..4399b05 100644 --- a/src/IPv4Address.hs +++ b/src/IPv4Address.hs @@ -5,26 +5,36 @@ module IPv4Address( most_sig_bit_different ) where +import Data.Int ( Int32, Int64 ) +import Data.Word ( Word32 ) -import Test.QuickCheck ( Gen ) -- Not re-exported by tasty import Test.Tasty ( TestTree, testGroup ) import Test.Tasty.HUnit ( (@?=), testCase ) import Test.Tasty.QuickCheck ( - Arbitrary(..), + Arbitrary( arbitrary ), + Gen, + Large, Property, + Small, (==>), testProperty ) -import Maskable (Maskable(..)) -import Maskbits (Maskbits(..)) -import Octet (Octet(..)) +import Maskable ( Maskable( apply_mask) ) +import Maskbits ( + Maskbits( + Zero, One, Two, Three, Four, Five, Six, Seven, Eight, + Nine, Ten, Eleven, Twelve, Thirteen, Fourteen, Fifteen, Sixteen, + Seventeen, Eighteen, Nineteen, Twenty, TwentyOne, TwentyTwo, TwentyThree, + TwentyFour, TwentyFive, TwentySix, TwentySeven, TwentyEight, TwentyNine, + Thirty, ThirtyOne, ThirtyTwo ) ) +import Octet ( Octet( b1, b2, b3, b4, b5, b6, b7, b8) ) data IPv4Address = IPv4Address { octet1 :: Octet, octet2 :: Octet, octet3 :: Octet, octet4 :: Octet } - deriving (Eq) + deriving (Eq, Ord) instance Show IPv4Address where @@ -182,22 +192,30 @@ instance Enum IPv4Address where -- | Convert an 'Int' @x@ to an 'IPv4Address'. Each octet of @x@ is -- right-shifted by the appropriate number of bits, and the fractional -- part is dropped. - toEnum x = + toEnum y = IPv4Address oct1 oct2 oct3 oct4 where + -- Convert the input Int to a Word32 before we proceed. On x86, + -- the Int that we get could be negative (half of all IP + -- addresses correspond to negative numbers), and then the magic + -- below doesn't work. The Word32 type is unsigned, so we do the + -- math on that and then convert everything back to Int later on + -- once we have four much-smaller non-negative numbers. + x = fromIntegral y :: Word32 + -- Chop off the higher octets. x1 = x `mod` 2^32, would be -- redundant. x2 = x `mod` 2^(24 :: Integer) x3 = x `mod` 2^(16 :: Integer) - x4 = x `mod` 2^(8 :: Integer) + x4 = (fromIntegral $ x `mod` 2^(8 :: Integer)) :: Int -- Perform right-shifts. x4 doesn't need a shift. - shifted_x1 = x `quot` 2^(24 :: Integer) - shifted_x2 = x2 `quot` 2^(16 :: Integer) - shifted_x3 = x3 `quot` 2^(8 :: Integer) - oct1 = toEnum shifted_x1 - oct2 = toEnum shifted_x2 - oct3 = toEnum shifted_x3 - oct4 = toEnum x4 + shifted_x1 = (fromIntegral $ x `quot` 2^(24 :: Integer)) :: Int + shifted_x2 = (fromIntegral $ x2 `quot` 2^(16 :: Integer)) :: Int + shifted_x3 = fromIntegral $ x3 `quot` 2^(8 :: Integer) :: Int + oct1 = toEnum shifted_x1 :: Octet + oct2 = toEnum shifted_x2 :: Octet + oct3 = toEnum shifted_x3 :: Octet + oct4 = toEnum x4 :: Octet -- | Convert @addr@ to an 'Int' by converting each octet to an 'Int' -- and shifting the result to the left by 0,8.16, or 24 bits. @@ -335,33 +353,62 @@ ipv4address_tests = test_minBound, test_most_sig_bit_different1, test_most_sig_bit_different2, + test_ord_instance1, + test_ord_instance2, + test_ord_instance3, + test_ord_instance4, test_to_enum ] ipv4address_properties :: TestTree ipv4address_properties = testGroup "IPv4 Address Properties " - [ prop_from_enum_to_enum_inverses ] + [ prop_from_enum_to_enum_inverses_x32, + prop_from_enum_to_enum_inverses_x64 ] -- QuickCheck properties -prop_from_enum_to_enum_inverses :: TestTree -prop_from_enum_to_enum_inverses = - testProperty "fromEnum and toEnum are inverses" prop +-- +-- We have two different tests to show that toEnum and fromEnum are +-- inverses of one another. This part of the code isn't really +-- type-safe, because the stupid Enum class insists that we use a +-- machine 'Int' for our representation. Since IPv4 addresses can +-- correspond to very large 32-bit integers, there's a possibility +-- that our math is wrong in 32- but not 64-bits, and vice-versa. +-- +-- tl;dr we want to ensure that this test passes when the 'Int' type +-- is both 32-bit and 64-bit. + +-- Generate "Small" 64-bit numbers, because almost all 64-bit integers are +-- too large to satisfy our predicate (i.e. also be 32-bit integers). +prop_from_enum_to_enum_inverses_x64 :: TestTree +prop_from_enum_to_enum_inverses_x64 = + testProperty "fromEnum and toEnum are inverses (x64)" prop + where + prop :: (Small Int64) -> Property + prop x = + 0 <= x && x <= 2^(32 :: Integer) - 1 ==> + fromIntegral (fromEnum (toEnum (fromIntegral x) :: IPv4Address)) == x + +-- According to the QuickCheck documentation, we need the "Large" +-- modifier to ensure that the test cases are drawn from the entire +-- range of Int32 values. +prop_from_enum_to_enum_inverses_x32 :: TestTree +prop_from_enum_to_enum_inverses_x32 = + testProperty "fromEnum and toEnum are inverses (x32)" prop where - prop :: Int -> Property + prop :: (Large Int32) -> Bool prop x = - (0 <= x) && (x <= 2^(32 :: Integer) - 1) ==> - fromEnum (toEnum x :: IPv4Address) == x + fromIntegral (fromEnum (toEnum (fromIntegral x) :: IPv4Address)) == x -- HUnit Tests mk_testaddr :: Int -> Int -> Int -> Int -> IPv4Address mk_testaddr a b c d = IPv4Address oct1 oct2 oct3 oct4 where - oct1 = toEnum a - oct2 = toEnum b - oct3 = toEnum c - oct4 = toEnum d + oct1 = toEnum a :: Octet + oct2 = toEnum b :: Octet + oct3 = toEnum c :: Octet + oct4 = toEnum d :: Octet test_minBound :: TestTree @@ -422,4 +469,50 @@ test_to_enum = where desc = "192.168.0.0 in base-10 is 3232235520" expected = mk_testaddr 192 168 0 0 - actual = toEnum 3232235520 + -- We declare the big number as Word32 because otherwise, on x86, + -- we get a warning that it's too big to fit in a 32-bit integer. + -- Ultimately we convert it to a (negative) Int on those systems + -- anyway, but the gymnastics declare our intent to the compiler. + actual = toEnum (fromIntegral (3232235520 :: Word32)) :: IPv4Address + + +test_ord_instance1 :: TestTree +test_ord_instance1 = + testCase desc $ actual @?= expected + where + desc = "127.0.0.0 is less than 127.0.0.1" + addr1 = mk_testaddr 127 0 0 0 + addr2 = mk_testaddr 127 0 0 1 + expected = True + actual = addr1 <= addr2 + + +test_ord_instance2 :: TestTree +test_ord_instance2 = + testCase desc $ actual @?= expected + where + desc = "127.0.0.0 is less than 127.0.1.0" + addr1 = mk_testaddr 127 0 0 0 + addr2 = mk_testaddr 127 0 1 0 + expected = True + actual = addr1 <= addr2 + +test_ord_instance3 :: TestTree +test_ord_instance3 = + testCase desc $ actual @?= expected + where + desc = "127.0.0.0 is less than 127.1.0.0" + addr1 = mk_testaddr 127 0 0 0 + addr2 = mk_testaddr 127 1 0 0 + expected = True + actual = addr1 <= addr2 + +test_ord_instance4 :: TestTree +test_ord_instance4 = + testCase desc $ actual @?= expected + where + desc = "127.0.0.0 is less than 128.0.0.0" + addr1 = mk_testaddr 127 0 0 0 + addr2 = mk_testaddr 128 0 0 0 + expected = True + actual = addr1 <= addr2