Add length tests and fix zero-length domain bug.

[email-validator.git] / src / Main.hs

diff --git a/src/Main.hs b/src/Main.hs
index f38a7db4b3f5c1d60a2067c34d18c2af512e29ec..9b22f5cfa20afe00ac3b82160a743781061ae754 100644 (file)
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -5,7 +5,7 @@ module Main
 where
 
 import Control.Concurrent.ParallelIO.Global (parallel, stopGlobalPool)
-import Control.Monad (when)
+import Control.Monad (unless)
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.UTF8 as BSU
 import Network.DNS (
@@ -26,12 +26,12 @@ import System.IO (
   openFile,
   stdin,
   stdout)
-import Text.Regex.PCRE.Light (compile, match, utf8)
+
 
 import CommandLine (Args(..), apply_args)
+import EmailAddress
 import ExitCodes (exit_input_file_doesnt_exist)
 
-type Address = BSU.ByteString
 
 -- | Resolver parameters. We increase the default timeout from 3 to 5
 --   seconds.
@@ -48,6 +48,8 @@ common_domains = map BSU.fromString [ "aol.com",
                                       "yahoo.com",
                                       "verizon.net" ]
 
+
+-- | Check whether the given domain has a valid MX record.
 validate_mx :: Resolver -> Domain -> IO Bool
 validate_mx resolver domain
   | domain `elem` common_domains = return True
@@ -57,44 +59,6 @@ validate_mx resolver domain
         Nothing -> return False
         _       -> return True
 
--- | Split an address into local/domain parts.
-parts :: Address -> (BSU.ByteString, BSU.ByteString)
-parts address = bytestring_split address '@'
-
--- | Check that the lengths of the local/domain parts are within spec.
-validate_length :: Address -> Bool
-validate_length address =
-  (BSU.length localpart <= 64) && (BSU.length domain <= 255)
-  where
-    (localpart, domain) = parts address
-
--- | Validate an email address against a simple regex. This should
---   catch common addresses but disallows a lot of (legal) weird stuff.
-validate_regex :: Address -> Bool
-validate_regex address =
-  case matches of
-    Nothing -> False
-    _       -> True
-  where
-    regex_str = "(\\w+)([\\w\\-\\.]*)@(([0-9a-zA-Z\\-]+\\.)+)[a-zA-Z]{2,4}"
-    regex_bs  = BSU.fromString regex_str
-    regex = compile regex_bs [utf8]
-    matches = match regex address []
-
--- | Validate the syntax of an email address by checking its length
---   and validating it against a simple regex.
-validate_syntax :: Address -> Bool
-validate_syntax address =
-  (validate_length address) && (validate_regex address)
-
--- | Split a 'ByteString' @s@ at the first occurrence of @character@.
-bytestring_split :: BSU.ByteString -> Char -> (BSU.ByteString, BSU.ByteString)
-bytestring_split s character =
-  (before, after)
-  where
-    break_func = (== character)
-    (before, rest) = BSU.break break_func s
-    after = BS.tail rest
 
 
 -- | Validate an email address by doing some simple syntax checks and
@@ -107,10 +71,11 @@ validate resolver address = do
     let (_,domain) = parts address
     mx_result <- validate_mx resolver domain
     return (address, mx_result)
-  else do
+  else
     return (address, False)
 
 
+-- | Append a ByteString to a file Handle, followed by a newline.
 append_handle_with_newline :: Handle -> BS.ByteString -> IO ()
 append_handle_with_newline h bs = do
   BS.hPutStr h bs
@@ -123,27 +88,39 @@ main :: IO ()
 main = do
   Args{..} <- apply_args
 
+  -- Get the input from either stdin, or the file given on the command
+  -- line.
   input <- case input_file of
              Nothing   -> BS.hGetContents stdin
              Just path -> do
                is_file <- doesFileExist path
-               when (not is_file) $ do
+               unless is_file $
                  exitWith (ExitFailure exit_input_file_doesnt_exist)
                BS.readFile path
 
+  -- Do the same for the output handle and stdout.
   output_handle <- case output_file of
                      Nothing -> return stdout
                      Just path -> openFile path WriteMode
 
+  -- Split the input into lines.
   let addresses = BSU.lines input
+
+  -- And remove the empty ones.
   let nonempty_addresses = filter (not . BS.null) addresses
 
   rs <- makeResolvSeed resolv_conf
   withResolver rs $ \resolver -> do
+    -- Construst a list of [IO (Address, Bool)]
     let actions = map (validate resolver) nonempty_addresses
+    -- And compute them in parallel.
     results <- parallel actions
     stopGlobalPool
+    -- Find the pairs with a True in the second position.
     let good_pairs = filter snd results
+    -- And output the results.
     mapM_ ((append_handle_with_newline output_handle) . fst) good_pairs
-    hFlush output_handle
-    hClose output_handle
+
+  -- Clean up. It's safe to try to close stdout.
+  hFlush output_handle
+  hClose output_handle