4 import Data.Maybe (fromJust)
12 -- | An Octet consists of eight bits. For our purposes, the most
13 -- significant bit will come "first." That is, b1 is in the 2^7
14 -- place while b8 is in the 2^0 place.
27 instance Show Octet where
28 show oct = show (octet_to_int oct)
31 instance Arbitrary Octet where
33 a1 <- arbitrary :: Gen Bit
34 a2 <- arbitrary :: Gen Bit
35 a3 <- arbitrary :: Gen Bit
36 a4 <- arbitrary :: Gen Bit
37 a5 <- arbitrary :: Gen Bit
38 a6 <- arbitrary :: Gen Bit
39 a7 <- arbitrary :: Gen Bit
40 a8 <- arbitrary :: Gen Bit
41 return (Octet a1 a2 a3 a4 a5 a6 a7 a8)
44 instance Maskable Octet where
45 apply_mask oct Eight _ = oct
47 apply_mask oct Seven bit =
50 apply_mask oct Six bit =
51 oct { b8 = bit, b7 = bit }
53 apply_mask oct Five bit =
54 oct { b8 = bit, b7 = bit, b6 = bit }
56 apply_mask oct Four bit =
57 oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit }
59 apply_mask oct Three bit =
60 oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit, b4 = bit }
62 apply_mask oct Two bit =
63 oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit, b4 = bit, b3 = bit }
65 apply_mask oct Maskbits.One bit =
66 oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit,
67 b4 = bit, b3 = bit, b2 = bit }
69 apply_mask oct Maskbits.Zero bit =
70 oct { b8 = bit, b7 = bit, b6 = bit, b5 = bit,
71 b4 = bit, b3 = bit, b2 = bit, b1 = bit }
73 -- The Maskbits must be in [Eight..ThirtyTwo].
74 apply_mask oct _ _ = oct
77 -- | Convert each bit to its integer value, and multiply by the
78 -- appropriate power of two. Sum them up, and we should get an integer
80 octet_to_int :: Octet -> Int
82 128 * (bit_to_int (b1 x)) +
83 64 * (bit_to_int (b2 x)) +
84 32 * (bit_to_int (b3 x)) +
85 16 * (bit_to_int (b4 x)) +
86 8 * (bit_to_int (b5 x)) +
87 4 * (bit_to_int (b6 x)) +
88 2 * (bit_to_int (b7 x)) +
89 1 * (bit_to_int (b8 x))
93 octet_from_int :: Int -> Maybe Octet
95 | (x < 0) || (x > 255) = Nothing
96 | otherwise = Just (Octet a1 a2 a3 a4 a5 a6 a7 a8)
98 a1 = if (x >= 128) then B.One else B.Zero
99 a2 = if ((x `mod` 128) >= 64) then B.One else B.Zero
100 a3 = if ((x `mod` 64) >= 32) then B.One else B.Zero
101 a4 = if ((x `mod` 32) >= 16) then B.One else B.Zero
102 a5 = if ((x `mod` 16) >= 8) then B.One else B.Zero
103 a6 = if ((x `mod` 8) >= 4) then B.One else B.Zero
104 a7 = if ((x `mod` 4) >= 2) then B.One else B.Zero
105 a8 = if ((x `mod` 2) == 1) then B.One else B.Zero
108 octet_from_string :: String -> Maybe Octet
109 octet_from_string s =
110 case (reads s :: [(Int, String)]) of
112 x:_ -> octet_from_int (fst x)
115 -- | The octet with the least possible value.
118 Octet B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero
121 -- | The octet with the greatest possible value.
124 Octet B.One B.One B.One B.One B.One B.One B.One B.One
129 test_octet_from_int1 :: Test
130 test_octet_from_int1 =
131 TestCase $ assertEqual "octet_from_int 128 should parse as 10000000" oct1 oct2
133 oct1 = Octet B.One B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero B.Zero
134 oct2 = fromJust $ octet_from_int 128
136 test_octet_mask1 :: Test
140 "The network bits of 255/4 should equal 240"
142 (apply_mask oct1 Four B.Zero)
144 oct1 = fromJust $ octet_from_int 255
145 oct2 = fromJust $ octet_from_int 240
148 test_octet_mask2 :: Test
152 "The network bits of 255/1 should equal 128"
154 (apply_mask oct1 Maskbits.One B.Zero)
156 oct1 = fromJust $ octet_from_int 255
157 oct2 = fromJust $ octet_from_int 128
160 octet_tests :: [Test]
162 [ test_octet_from_int1,