X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FMain.hs;h=38dd2e5ad5e8af5c4336c667507a6a87b74c0ccd;hb=bb74b494c23a737b9c0355148d25f090545b856b;hp=829440ec35fa1a364d11a6b9605edf866df0bd94;hpb=d4d924b26e451aec9ad84b6d9d376ba2aeab3422;p=dead%2Fhtsn.git diff --git a/src/Main.hs b/src/Main.hs index 829440e..38dd2e5 100644 --- a/src/Main.hs +++ b/src/Main.hs @@ -4,20 +4,19 @@ module Main where -import Control.Concurrent (threadDelay) -import Control.DeepSeq (deepseq) -import Control.Exception.Base (bracket) -import Control.Monad (forever, when) -import Data.List (isPrefixOf) -import Data.Maybe (isNothing) -import Data.Monoid ((<>)) +import Control.Concurrent ( threadDelay ) +import Control.Exception ( bracket, throw ) +import Control.Monad ( when ) +import Data.List ( isPrefixOf ) +import Data.Maybe ( isNothing ) +import Data.Monoid ( (<>) ) import Network ( connectTo, PortID (PortNumber) ) -import System.Console.CmdArgs (def) -import System.Directory (doesFileExist) -import System.Exit (ExitCode(..), exitWith) -import System.FilePath (()) +import System.Console.CmdArgs ( def ) +import System.Directory ( doesFileExist ) +import System.Exit ( ExitCode(..), exitWith ) +import System.FilePath ( () ) import System.IO ( BufferMode (NoBuffering), Handle, @@ -28,125 +27,221 @@ import System.IO ( hSetBuffering, stderr, stdout ) -import System.IO.Error (catchIOError) +import System.IO.Error ( catchIOError ) +import System.Timeout ( timeout ) -import CommandLine (get_args) -import Configuration (Configuration(..), merge_optional) +import CommandLine ( get_args ) +import Configuration ( Configuration(..), merge_optional ) import ExitCodes ( exit_no_feed_hosts, exit_no_password, - exit_no_username ) -import FeedHosts (FeedHosts(..)) + exit_no_username, + exit_pidfile_exists ) +import FeedHosts ( FeedHosts(..) ) +import Network.Services.TSN.Logging ( init_logging ) import qualified OptionalConfiguration as OC ( OptionalConfiguration(..), from_rc ) -import Terminal (hPutRedLn, putGreenLn) -import TSN.Xml (parse_xmlfid, xml_prologue) - - -report_error :: String -> IO () -report_error = hPutRedLn stderr +import Network.Services.TSN.Report ( + report_debug, + report_info, + report_warning, + report_error ) +import Network.Services.TSN.Terminal ( display_sent ) +import Xml ( parse_xmlfid ) +import Unix ( full_daemonize ) +-- | Receive a single line of text from a Handle, and send it to the +-- debug log. +-- recv_line :: Handle -> IO String recv_line h = do line <- hGetLine h - putStrLn line + report_debug (line ++ "\n") 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. +-- +-- 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 cfg doc = do - case maybe_path of - Nothing -> - report_error "ERROR: document missing XML_File_ID element." - Just path -> do +save_document cfg doc = + case either_path of + Left err -> report_error err + Right path -> do already_exists <- doesFileExist path when already_exists $ do - let msg = "WARNING: file " ++ path ++ " already exists. Overwriting." - report_error msg + let msg = "File " ++ path ++ " already exists, overwriting." + report_warning msg writeFile path doc + report_info $ "Wrote file: " ++ path ++ "." where + -- All the fmaps are because we're working inside a Maybe. xmlfid = fmap show (parse_xmlfid doc) filename = fmap (++ ".xml") xmlfid - maybe_path = fmap ((output_directory cfg) ) filename + either_path = fmap ((output_directory cfg) ) filename --- | Loop forever, writing the buffer to file whenever a new XML --- prologue is seen. + +-- | 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 +-- that \ will always be the root element of the XML +-- documents, and \ will be the final line transmitted +-- for a given document. We therefore rely on this to simplify +-- processing. +-- loop :: Configuration -> Handle -> [String] -> IO () loop !cfg !h !buffer = do line <- recv_line h + let new_buffer = line : buffer - if (xml_prologue `isPrefixOf` line && not (null 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 - -- This is the beginning of a new document, and we have an "old" - -- one to save. 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 buffer + -- 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 [line] -- empty the buffer before looping again + loop cfg h [] -- Empty the buffer before looping again. else - loop cfg h (line : buffer) -- append line to the head of the buffer and loop + -- Append line to the head of the buffer and loop. + loop cfg h new_buffer +-- | 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 if prompt1 /= username_prompt then - report_error "ERROR: didn't receive username prompt." + 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 "ERROR: didn't receive password prompt." + report_error "Didn't receive password prompt." else do - send_line h (password cfg) - banner <- recv_line h -- "The Sports Network" - banner `deepseq` return () + 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 - hPutStr h' (s ++ "\r\n") - putGreenLn s + send_cred :: Handle -> String -> IO () + send_cred h' s = do + -- The carriage return is super important! + let line = s ++ "\r\n" + hPutStr h' line + display_sent line -- Don't log the username/password! recv_chars :: Int -> Handle -> IO String recv_chars n h' = do s <- sequence [ hGetChar h' | _ <- [1..n] ] - putStr s + report_debug s return s recv_prompt :: Handle -> IO String recv_prompt = recv_chars 10 -connect_and_loop :: Configuration -> IO () -connect_and_loop cfg = + +-- | 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 the host on the XML port +-- +-- 2. Log in +-- +-- 3. Go into the eternal read/save loop. +-- +connect_and_parse :: Configuration -> String -> IO () +connect_and_parse cfg host = do + report_info $ "Connecting to " ++ host ++ "." bracket acquire_handle release_handle action + return () where - --acquire_handle = connectTo "feed1.sportsnetwork.com" (PortNumber 4500) - acquire_handle = connectTo "feed2.sportsnetwork.com" (PortNumber 4500) - --acquire_handle = connectTo "127.0.0.1" (PortNumber 13337) + five_seconds :: Int + five_seconds = 5000000 + + acquire_handle = connectTo host (PortNumber 4500) release_handle = hClose action h = do -- No buffering anywhere. hSetBuffering h NoBuffering - log_in cfg h - loop cfg h [] + + -- The feed is often unresponsive after we send out username. It + -- happens in a telnet session, too (albeit less frequently?), + -- so there might be a bug on their end. + -- + -- If we dump the packets with tcpdump, it looks like their + -- software is getting confused: they send us some XML in + -- the middle of the log-in procedure. + -- + -- On the other hand, the documentation at + -- + -- states that you can only make one connection per username to + -- a given host. So maybe they're simply rejecting the username + -- in an unfriendly fashion. In any case, the easiest fix is to + -- disconnect and try again. + -- + login_worked <- timeout five_seconds $ log_in cfg h + case login_worked of + Nothing -> report_info $ "Login timed out (5 seconds). " + ++ "Waiting 5 seconds to reconnect." + Just _ -> loop cfg h [] -- | A wrapper around threadDelay which takes seconds instead of -- microseconds as its argument. +-- thread_sleep :: Int -> 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 @@ -156,25 +251,78 @@ main = do -- prefering the command-line ones. let opt_config = rc_cfg <> cmd_cfg + -- Update a default config with any options that have been set in + -- either the config file or on the command-line. We initialize + -- 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_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 + -- hostnames in e.g. the config file, we want to bail rather than + -- fall back on the default list (which was merged from a default + -- Configuration above). when (null $ get_feed_hosts (OC.feed_hosts opt_config)) $ do - report_error "ERROR: no feed hosts supplied." + report_error "No feed hosts supplied." exitWith (ExitFailure exit_no_feed_hosts) when (isNothing (OC.password opt_config)) $ do - report_error "ERROR: no password supplied." + report_error "No password supplied." exitWith (ExitFailure exit_no_password) when (isNothing (OC.username opt_config)) $ do - report_error "ERROR: no username supplied." + report_error "No username supplied." exitWith (ExitFailure exit_no_username) - -- Finally, update a default config with any options that have been - -- set in either the config file or on the command-line. - let cfg = (def :: Configuration) `merge_optional` opt_config + 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. " + ++ "Refusing to start." + exitWith (ExitFailure exit_pidfile_exists) + -- This may be superstition (and I believe stderr is unbuffered), + -- but it can't hurt. hSetBuffering stderr NoBuffering hSetBuffering stdout NoBuffering - forever $ do - catchIOError (connect_and_loop cfg) (report_error . show) - thread_sleep 10 -- Wait 10s before attempting to reconnect. + -- The rest of the program is kicked off by the following line which + -- begins connecting to our feed hosts, starting with the first one, + -- and proceeds in a round-robin fashion. + let run_program = round_robin cfg 0 + + -- If we were asked to daemonize, do that; otherwise just run the thing. + if (daemonize cfg) + then try_daemonize cfg run_program + else run_program + + where + -- | 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. + -- + -- Afterwards, we recurse (call ourself) again to loop more forevers. + -- + round_robin :: Configuration -> Int -> IO () + round_robin cfg feed_host_idx = do + let hosts = get_feed_hosts $ feed_hosts cfg + let host = hosts !! feed_host_idx + 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)