X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FMain.hs;h=0a2f7d7473482d624935cccc931600c39494aa4c;hb=ac97e3119df309c4eaaff0c72e5b5879f156616f;hp=b6403614d5d46af193e1f7b2b2adef5ccc8c4bcd;hpb=f6cb0ba712e06e52d080b86e9eba6c3585a7514b;p=dead%2Fhtsn.git diff --git a/src/Main.hs b/src/Main.hs index b640361..0a2f7d7 100644 --- a/src/Main.hs +++ b/src/Main.hs @@ -4,8 +4,9 @@ module Main where +-- System imports. import Control.Concurrent ( threadDelay ) -import Control.Exception.Base ( bracket ) +import Control.Exception ( bracket, throw ) import Control.Monad ( when ) import Data.List ( isPrefixOf ) import Data.Maybe ( isNothing ) @@ -13,6 +14,13 @@ import Data.Monoid ( (<>) ) import Network ( connectTo, PortID (PortNumber) ) +import Network.Services.TSN.Logging ( init_logging ) +import Network.Services.TSN.Report ( + report_debug, + report_info, + report_warning, + report_error ) +import Network.Services.TSN.Terminal ( display_sent ) import System.Console.CmdArgs ( def ) import System.Directory ( doesFileExist ) import System.Exit ( ExitCode(..), exitWith ) @@ -30,6 +38,7 @@ import System.IO ( import System.IO.Error ( catchIOError ) import System.Timeout ( timeout ) +-- Local imports. import CommandLine ( get_args ) import Configuration ( Configuration(..), merge_optional ) import ExitCodes ( @@ -37,63 +46,16 @@ import ExitCodes ( exit_no_password, exit_no_username, exit_pidfile_exists ) -import Logging ( - init_logging, - log_debug, - log_error, - log_info, - log_warning ) +import FeedHosts ( FeedHosts(..) ) import qualified OptionalConfiguration as OC ( OptionalConfiguration(..), from_rc ) -import Terminal ( - display_debug, - display_error, - display_info, - display_sent, - display_warning ) -import TSN.FeedHosts ( FeedHosts(..) ) -import TSN.Xml ( parse_xmlfid ) +import Xml ( parse_xmlfid ) import Unix ( full_daemonize ) --- | Display and log debug information. WARNING! This does not --- automatically append a newline. The output is displayed/logged --- as-is, for, you know, debug purposes. -report_debug :: String -> IO () -report_debug s = do - display_debug s - log_debug s - --- | Display and log an error condition. This will prefix the error --- with "ERROR: " when displaying (but not logging) it so that it --- stands out. --- -report_error :: String -> IO () -report_error s = do - display_error $ "ERROR: " ++ s - log_error s - - --- | Display and log an informational (status) message. -report_info :: String -> IO () -report_info s = do - display_info s - log_info s - - --- | Display and log a warning. This will prefix the warning with --- "WARNING: " when displaying (but not logging) it so that it --- stands out. --- -report_warning :: String -> IO () -report_warning s = do - display_warning $ "WARNING: " ++ s - log_warning s - - --- | Receive a single line of text from a Handle, and send it to the --- debug log. +-- | Receive a single line of text from a 'Handle', and record it for +-- debugging purposes. -- recv_line :: Handle -> IO String recv_line h = do @@ -102,14 +64,16 @@ recv_line h = do return line --- | Takes a Configuration, and an XML document (as a String). The XML --- document is written to the output directory, as specified by the --- Configuration. +-- | Takes a 'Configuration', and an XML document (as a 'String'). The +-- XML document is written to the output directory, as specified by +-- the 'Configuration'. -- -- This can fail, but we don't purposefully throw any exceptions. If -- something goes wrong, we would rather log it and keep going. -- -save_document :: Configuration -> String -> IO () +save_document :: Configuration + -> String -- ^ String representation of an XML document + -> IO () save_document cfg doc = case either_path of Left err -> report_error err @@ -127,9 +91,9 @@ save_document cfg doc = either_path = fmap ((output_directory cfg) ) filename --- | Loop forever, writing the buffer to file whenever a --- tag is seen. This is the low-level "loop forever" function that --- we stay in as long as we are connected to one feed. +-- | Loop forever, writing the @buffer@ to file whenever a +-- \ tag is seen. This is the low-level \"loop forever\" +-- function that we stay in as long as we are connected to one feed. -- -- The documentation at -- states @@ -138,27 +102,74 @@ save_document cfg doc = -- for a given document. We therefore rely on this to simplify -- processing. -- -loop :: Configuration -> Handle -> [String] -> IO () +-- The bang pattern at least on @buffer@ is necessary for +-- performance reasons. +-- +-- We specify a timeout of fifteen minutes on the 'recv_line' +-- function, after which we will return to our caller. This should +-- cause the connection to be dropped, and a new one initiated. The +-- timeout is in response to observed behavior where the feed +-- eventually stops transmitting data entirely without closing the +-- connection. +-- +loop :: Configuration + -> Handle -- ^ Handle to the feed (network connection) + -> [String] -- ^ Current XML document buffer, line-by-line, in reverse + -> IO () loop !cfg !h !buffer = do - line <- recv_line h - let new_buffer = line : buffer - - -- Use isPrefixOf to avoid line-ending issues. Hopefully they won't - -- send invalid junk (on the same line) after closing the root - -- element. - if "" `isPrefixOf` line - then do - -- The buffer is in reverse (newest first) order, though, so we - -- have to reverse it first. We then concatenate all of its lines - -- into one big string. - let document = concat $ reverse new_buffer - save_document cfg document - loop cfg h [] -- Empty the buffer before looping again. - else - -- Append line to the head of the buffer and loop. - loop cfg h new_buffer + line' <- timeout fifteen_minutes $ recv_line h + case line' of + -- If we haven't received anything in fifteen minutes, return back + -- to the calling function. This should only happen in the case of + -- an error, and our caller should be prepared to handle it. + Nothing -> do + report_warning $ "No data received for 15 minutes." + Just line -> do + -- If the recv didn't timeout, proceed normally. + let new_buffer = line : buffer + + -- Use isPrefixOf to avoid line-ending issues. Hopefully they won't + -- send invalid junk (on the same line) after closing the root + -- element. + if "" `isPrefixOf` line + then do + -- The buffer is in reverse (newest first) order, though, so we + -- have to reverse it first. We then concatenate all of its lines + -- into one big string. + let document = concat $ reverse new_buffer + save_document cfg document + loop cfg h [] -- Empty the buffer before looping again. + else + -- Append line to the head of the buffer and loop. + loop cfg h new_buffer + where + fifteen_minutes :: Int + fifteen_minutes = 15 * 60 * 1000000 +-- | Once we're connected to a feed, we need to log in. There's no +-- protocol for this (the docs don't mention one), but we have +-- (apparently) successfully guessed it. +-- +-- The first thing TSN sends once we've connected is the string +-- \"Username: \", containing 10 ASCII characters. We then send a +-- username, followed by a newline. If TSN likes the username, the +-- second they'll send is the string \"Password: \", also containing +-- 10 ASCII characters, to which we reply in kind. +-- +-- Assuming the above will always hold, it is implemented as follows: +-- +-- 1. Receive 10 chars +-- +-- 2. Send username if we got the username prompt +-- +-- 3. Receive 10 chars +-- +-- 4. Send password if we got the password prompt +-- +-- If TSN likes the password as well, they send the string \"The +-- Sports Network\" before finally beginning to stream the feed. +-- log_in :: Configuration -> Handle -> IO () log_in cfg h = do prompt1 <- recv_prompt h @@ -166,25 +177,26 @@ log_in cfg h = do if prompt1 /= username_prompt then report_error "Didn't receive username prompt." else do - send_line h (username cfg) + send_cred h (username cfg) prompt2 <- recv_prompt h if prompt2 /= password_prompt then report_error "Didn't receive password prompt." else do - send_line h (password cfg) + send_cred h (password cfg) _ <- recv_line h -- "The Sports Network" + report_info $ "Logged in as " ++ (username cfg) ++ "." return () where username_prompt = "Username: " password_prompt = "Password: " - send_line :: Handle -> String -> IO () - send_line h' s = do + send_cred :: Handle -> String -> IO () + send_cred h' s = do + -- The carriage return is super important! let line = s ++ "\r\n" hPutStr h' line - -- Don't log the username/password! - display_sent line + display_sent line -- Don't log the username/password! recv_chars :: Int -> Handle -> IO String recv_chars n h' = do @@ -196,17 +208,37 @@ log_in cfg h = do recv_prompt = recv_chars 10 -connect_and_loop :: Configuration -> String -> IO () -connect_and_loop cfg host = do - report_info $ "Connecting to " ++ host ++ "." +-- | Connect to @host@ and attempt to parse the feed. As long as we +-- stay connected and nothing bad happens, the program will remain in +-- this function. If anything goes wrong, then the current invocation +-- of connect_and_parse will return, and get called again later +-- (probably with a different @host@). +-- +-- Steps: +-- +-- 1. Connect to @host@ on the XML feed port. +-- +-- 2. Log in. +-- +-- 3. Go into the eternal read/save loop. +-- +connect_and_parse :: Configuration + -> String -- ^ Hostname to connect to + -> IO () +connect_and_parse cfg host = do bracket acquire_handle release_handle action - return () where five_seconds :: Int - five_seconds = 5000000 + five_seconds = 5 * 1000000 + + acquire_handle = do + report_info $ "Connecting to " ++ host ++ "." + connectTo host (PortNumber 4500) + + release_handle = \h -> do + report_info $ "Closing connection to " ++ host ++ "." + hClose h - acquire_handle = connectTo host (PortNumber 4500) - release_handle = hClose action h = do -- No buffering anywhere. hSetBuffering h NoBuffering @@ -228,20 +260,27 @@ connect_and_loop cfg host = do -- login_worked <- timeout five_seconds $ log_in cfg h case login_worked of - Nothing -> report_info "Login timed out (5s)." + Nothing -> report_info $ "Login timed out (5 seconds). " + ++ "Waiting 5 seconds to reconnect." + + -- If loop returns (due to its timeout), it will pop out right + -- here and the action will terminate causing 'release_handle' + -- to trigger. Just _ -> loop cfg h [] -- | A wrapper around threadDelay which takes seconds instead of -- microseconds as its argument. -- -thread_sleep :: Int -> IO () +thread_sleep :: Int -- ^ Number of seconds for which to sleep. + -> IO () thread_sleep seconds = do let microseconds = seconds * (10 ^ (6 :: Int)) threadDelay microseconds -- | The entry point of the program. +-- main :: IO () main = do rc_cfg <- OC.from_rc @@ -256,7 +295,7 @@ main = do -- logging before the missing parameter checks below so that we can -- log the errors. let cfg = (def :: Configuration) `merge_optional` opt_config - init_logging (log_file cfg) (log_level cfg) (syslog cfg) + init_logging (log_level cfg) (log_file cfg) (syslog cfg) -- Check the optional config for missing required options. This is -- necessary because if the user specifies an empty list of @@ -276,6 +315,8 @@ main = do exitWith (ExitFailure exit_no_username) when (daemonize cfg) $ do + -- Old PID files can be left around after an unclean shutdown. We + -- only care if we're running as a daemon. pidfile_exists <- doesFileExist (pidfile cfg) when pidfile_exists $ do report_error $ "PID file " ++ (pidfile cfg) ++ " already exists. " @@ -294,11 +335,11 @@ main = do -- If we were asked to daemonize, do that; otherwise just run the thing. if (daemonize cfg) - then full_daemonize cfg run_program + then try_daemonize cfg run_program else run_program where - -- | This is the top-level "loop forever" function. If an + -- | This is the top-level \"loop forever\" function. If an -- exception is thrown, it will propagate up to this point, where -- it will be logged and ignored in style. -- @@ -308,6 +349,19 @@ main = do round_robin cfg feed_host_idx = do let hosts = get_feed_hosts $ feed_hosts cfg let host = hosts !! feed_host_idx - catchIOError (connect_and_loop cfg host) (report_error . show) + catchIOError (connect_and_parse cfg host) (report_error . show) thread_sleep 5 -- Wait 5s before attempting to reconnect. round_robin cfg $ (feed_host_idx + 1) `mod` (length hosts) + + + -- | A exception handler around full_daemonize. If full_daemonize + -- doesn't work, we report the error and crash. This is fine; we + -- only need the program to be resilient once it actually starts. + -- + try_daemonize :: Configuration -> IO () -> IO () + try_daemonize cfg program = + catchIOError + (full_daemonize cfg program) + (\e -> do + report_error (show e) + throw e)