src/Main.hs

   1 import Data.List ((\\), intercalate, intersperse)
   2 import System.Exit (ExitCode(..), exitWith)
   3 import System.IO (stderr, hPutStrLn)
   4
   5 import Cidr (Cidr(..),
   6              cidr_from_string,
   7              combine_all)
   8
   9 import CommandLine (help_set,
  10                     help_text,
  11                     input_function,
  12                     Mode(..),
  13                     parse_errors,
  14                     parse_mode)
  15
  16 import IPv4Address
  17 import Octet
  18
  19 -- Some exit codes, used in the ExitFailure constructor.
  20 exit_invalid_cidr :: Int
  21 exit_invalid_cidr = 1
  22
  23 exit_args_parse_failed :: Int
  24 exit_args_parse_failed = 2
  25
  26
  27 -- A regular expression that matches a non-address character.
  28 non_addr_char :: String
  29 non_addr_char = "[^\\.0-9]"
  30
  31
  32 -- Add non_addr_chars on either side of the given String. This
  33 -- prevents (for example) the regex '127.0.0.1' from matching
  34 -- '127.0.0.100'.
  35 addr_barrier :: String -> String
  36 addr_barrier x = non_addr_char ++ x ++ non_addr_char
  37
  38
  39 -- The magic happens here. We take a CIDR String as an argument, and
  40 -- return the equivalent regular expression. We do this as follows:
  41 --
  42 -- 1. Compute the minimum possible value of each octet.
  43 -- 2. Compute the maximum possible value of each octet.
  44 -- 3. Generate a regex matching every value between those min and
  45 --    max values.
  46 -- 4. Join the regexes from step 3 with regexes matching periods.
  47 -- 5. Stick an address boundary on either side of the result.
  48 --cidr_to_regex :: String -> String
  49 cidr_to_regex :: Cidr.Cidr -> String
  50 cidr_to_regex cidr =
  51     addr_barrier (intercalate "\\." [range1, range2, range3, range4])
  52     where
  53       range1 = numeric_range min1 max1
  54       range2 = numeric_range min2 max2
  55       range3 = numeric_range min3 max3
  56       range4 = numeric_range min4 max4
  57       min1   = octet_to_int (min_octet1 (ipv4address cidr) (maskbits cidr))
  58       min2   = octet_to_int (min_octet2 (ipv4address cidr) (maskbits cidr))
  59       min3   = octet_to_int (min_octet3 (ipv4address cidr) (maskbits cidr))
  60       min4   = octet_to_int (min_octet4 (ipv4address cidr) (maskbits cidr))
  61       max1   = octet_to_int (max_octet1 (ipv4address cidr) (maskbits cidr))
  62       max2   = octet_to_int (max_octet2 (ipv4address cidr) (maskbits cidr))
  63       max3   = octet_to_int (max_octet3 (ipv4address cidr) (maskbits cidr))
  64       max4   = octet_to_int (max_octet4 (ipv4address cidr) (maskbits cidr))
  65
  66
  67
  68 -- Take a list of Strings, and return a regular expression matching
  69 -- any of them.
  70 alternate :: [String] -> String
  71 alternate terms = "(" ++ (concat (intersperse "|" terms)) ++ ")"
  72
  73
  74 -- Take two Ints as parameters, and return a regex matching any
  75 -- integer between them (inclusive).
  76 numeric_range :: Int -> Int -> String
  77 numeric_range x y =
  78     alternate (map show [lower..upper])
  79      where
  80        lower = minimum [x,y]
  81        upper = maximum [x,y]
  82
  83
  84 main :: IO ()
  85 main = do
  86   -- First, check for any errors that occurred while parsing
  87   -- the command line options.
  88   errors <- CommandLine.parse_errors
  89   if not (null errors)
  90     then do
  91       hPutStrLn stderr (concat errors)
  92       putStrLn CommandLine.help_text
  93       exitWith (ExitFailure exit_args_parse_failed)
  94     else do -- Nothing
  95
  96   -- Next, check to see if the 'help' option was passed to the
  97   -- program. If it was, display the help, and exit successfully.
  98   help_opt_set <- CommandLine.help_set
  99   if help_opt_set
 100     then do
 101       putStrLn CommandLine.help_text
 102       exitWith ExitSuccess
 103     else do -- Nothing
 104
 105   -- The input function we receive here should know what to read.
 106   inputfunc <- (CommandLine.input_function)
 107   input <- inputfunc
 108
 109   let cidr_strings = lines input
 110   let cidrs = map Cidr.cidr_from_string cidr_strings
 111
 112   if (any (== Cidr.None) cidrs)
 113     then do
 114       putStrLn "Error: not valid CIDR notation."
 115       exitWith (ExitFailure exit_invalid_cidr)
 116     else do -- Nothing
 117
 118   -- Get the mode of operation.
 119   mode <- CommandLine.parse_mode
 120
 121   case mode of
 122     Regex -> do
 123         let regexes = map cidr_to_regex cidrs
 124         putStrLn $ alternate regexes
 125     Reduce -> do
 126         mapM (putStrLn . show) (combine_all cidrs)
 127         return ()
 128     Dupe -> do
 129          mapM (putStrLn . show) dupes
 130          return ()
 131          where
 132            dupes = cidrs \\ (combine_all cidrs)