-module Mail
+-- | Email functions and data types.
+
+module Mail (
+ Message(..),
+ print_sendmail_result,
+ rfc822_now,
+ sendmail )
where
-import Control.Concurrent
-import Control.Concurrent.MVar
-import Control.Exception (evaluate)
-import Data.List (intercalate)
-import System.Exit
-import System.Process
-import System.IO
+import Control.Concurrent ( forkIO, newEmptyMVar, putMVar, readMVar )
+import Control.Exception ( evaluate )
+import Control.Monad ( liftM )
+import Data.List ( intercalate )
+import Data.Time ( formatTime, getZonedTime )
+import System.Console.CmdArgs.Default ( Default(..) )
+import System.Exit ( ExitCode(..) )
+import System.Locale ( defaultTimeLocale, rfc822DateFormat )
+import System.Process ( runInteractiveProcess, waitForProcess )
+import System.IO ( hClose, hGetContents, hPutStr )
+
type Header = String
+-- | The default headers attached to each message. The MIME junk is
+-- needed for UTF-8 to work properly. Note that your mail server
+-- should support the 8BITMIME extension.
+--
+default_headers :: [Header]
+default_headers = ["MIME-Version: 1.0",
+ "Content-Type: text/plain; charset=UTF-8",
+ "Content-Transfer-Encoding: 8bit"]
+
+
+-- | A crude model of an RFC822 email message.
+--
data Message = Message { headers :: [Header],
subject :: String,
body :: String,
to :: String }
deriving (Eq)
-instance Show Message where
- show m =
- concat [ if (length (headers m) == 0) then "" else (intercalate "\n" (headers m)) ++ "\n",
- "Subject: " ++ (subject m) ++ "\n",
- "From: " ++ (from m) ++ "\n",
- "To: " ++ (to m) ++ "\n",
- "\n",
- (body m) ]
-
-
-sendmail :: Message -> IO (String, String, ExitCode)
-sendmail message = do
+
+instance Default Message where
+ -- | Construct a message with all of its fields set to their
+ -- default values.
+ --
+ def = Message default_headers def def def def
+
+
+-- | Print a 'Message' in roughly RFC-compliant form. This form is
+-- sufficient for handing the message off to sendmail (or compatible).
+--
+-- Examples:
+--
+-- >>> let hs = default_headers
+-- >>> let s = "Save up to 20% on garbage!"
+-- >>> let b = "Just kidding, now you have a virus!"
+-- >>> let f = "savings5000@impenetrable.example"
+-- >>> let t = "everyone@everywhere.example"
+-- >>> let msg = Message hs s b f t
+-- >>> putStrLn $ to_rfc822 msg
+-- MIME-Version: 1.0
+-- Content-Type: text/plain; charset=UTF-8
+-- Content-Transfer-Encoding: 8bit
+-- Subject: Save up to 20% on garbage!
+-- From: savings5000@impenetrable.example
+-- To: everyone@everywhere.example
+-- <BLANKLINE>
+-- Just kidding, now you have a virus!
+--
+to_rfc822 :: Message -> String
+to_rfc822 m =
+ concat [ formatted_headers,
+ "Subject: " ++ (subject m) ++ "\n",
+ "From: " ++ (from m) ++ "\n",
+ "To: " ++ (to m) ++ "\n",
+ "\n",
+ (body m) ]
+ where
+ formatted_headers =
+ if null (headers m)
+ then ""
+ else (intercalate "\n" (headers m)) ++ "\n"
+
+
+
+-- | Constructs a 'String' in RFC822 date format for the current
+-- date/time.
+--
+rfc822_now :: IO String
+rfc822_now =
+ liftM (formatTime defaultTimeLocale rfc822DateFormat) getZonedTime
+
+
+
+
+-- | Takes a message as an argument, and passes it to the system's
+-- sendmail (or compatible) binary.
+--
+sendmail :: FilePath -> Message -> IO (String, String, ExitCode)
+sendmail sendmail_path message = do
+ -- The arguments we pass to sendmail "on the command line"
let sendmail_args = ["-f",
- (from message)]
+ (from message),
+ (to message)]
+ -- Run the sendmail process, passing it our sendmail_args. We'll get
+ -- back a bunch of handles, std{in,out,err} and one for the process
+ -- itself.
(inh, outh, errh, ph) <-
- runInteractiveProcess "/usr/bin/sendmail" sendmail_args Nothing Nothing
+ runInteractiveProcess sendmail_path sendmail_args Nothing Nothing
+ -- Create mvars for stdout and stderr, then collect their contents.
outm <- newEmptyMVar
outs <- hGetContents outh
errm <- newEmptyMVar
errs <- hGetContents errh
- forkIO $ hPutStr inh (show message) >> hClose inh
- forkIO $ evaluate (length outs) >> putMVar outm ()
- forkIO $ evaluate (length errs) >> putMVar errm ()
+ -- Pass the message to sendmail on stdin
+ _ <- forkIO $ hPutStr inh (to_rfc822 message) >> hClose inh
+
+ -- Fork threads that will read stdout/stderr respectively, and then
+ -- stick a dummy unit value in the mvars we created.
+ _ <- forkIO $ evaluate (length outs) >> putMVar outm ()
+ _ <- forkIO $ evaluate (length errs) >> putMVar errm ()
+ -- Now wait for the dummy variables to show up in the mvars. This
+ -- will occur only after (length outs) and (length errs) have been
+ -- evaluated, which can happen only after we've read them entirely.
readMVar outm
readMVar errm
+ -- Now wait for the process to finish and return its exit code along
+ -- with the output that we collected.
ec <- waitForProcess ph
return (outs, errs, ec)
+-- | The 'sendmail' function returns a three-tuple of its outputs,
+-- errors, and exit codes. This function pretty-prints one of those
+-- three-tuples.
+--
+-- If the exit code indicates success, we don't bother to print
+-- anything (silence is golden!), but otherwise the contents of both
+-- stdout and stderr will be printed.
+--
+-- Examples:
+--
+-- >>> let r = ("some output", "no errors", ExitSuccess)
+-- >>> print_sendmail_result r
+--
+-- >>> let r = ("some output", "lots of errors", ExitFailure 1)
+-- >>> print_sendmail_result r
+-- Output: some output
+-- Errors: lots of errors
+-- Exit Code: 1
+--
print_sendmail_result :: (String, String, ExitCode) -> IO ()
-print_sendmail_result (outs, errs, ec) = do
- case ec of
- ExitSuccess -> return ()
- _ -> putStrLn $ concat ["Output: " ++ outs,
- "\nErrors: " ++ errs,
- "\nExit Code: " ++ (show ec)]
+print_sendmail_result (outs, errs, ec) =
+ case ec of
+ ExitSuccess -> return ()
+ ExitFailure (code) ->
+ putStrLn $ concat ["Output: " ++ outs,
+ "\nErrors: " ++ errs,
+ "\nExit Code: " ++ (show code)]
projects / dead / halcyon.git / blobdiff