{-# LANGUAGE CPP #-} {- | Module : System.Log.Handler.Syslog Copyright : Copyright (C) 2004-2011 John Goerzen License : BSD3 Maintainer : John Goerzen Stability : provisional Portability: portable Syslog handler for the Haskell Logging Framework Written by John Goerzen, jgoerzen\@complete.org This module implements an interface to the Syslog service commonly found in Unix\/Linux systems. This interface is primarily of interest to developers of servers, as Syslog does not typically display messages in an interactive fashion. This module is written in pure Haskell and is capable of logging to a local or remote machine using the Syslog protocol. You can create a new Syslog 'LogHandler' by calling 'openlog'. More information on the Haskell Logging Framework can be found at "System.Log.Logger". This module can also be used outside of the rest of that framework for those interested in that. -} module System.Log.Handler.Syslog( -- * Handler Initialization openlog, -- * Advanced handler initialization #ifndef mingw32_HOST_OS openlog_local, #endif openlog_remote, openlog_generic, -- * Data Types Facility(..), Option(..) ) where import System.Log import System.Log.Formatter import System.Log.Handler import Data.Bits import Network.Socket import Network.BSD import Data.List #ifndef mingw32_HOST_OS import System.Posix.Process(getProcessID) #endif import System.IO code_of_pri :: Priority -> Int code_of_pri p = case p of EMERGENCY -> 0 ALERT -> 1 CRITICAL -> 2 ERROR -> 3 WARNING -> 4 NOTICE -> 5 INFO -> 6 DEBUG -> 7 {- | Facilities are used by the system to determine where messages are sent. -} data Facility = KERN -- ^ Kernel messages; you should likely never use this in your programs | USER -- ^ General userland messages. Use this if nothing else is appropriate | MAIL -- ^ E-Mail system | DAEMON -- ^ Daemon (server process) messages | AUTH -- ^ Authentication or security messages | SYSLOG -- ^ Internal syslog messages; you should likely never use this in your programs | LPR -- ^ Printer messages | NEWS -- ^ Usenet news | UUCP -- ^ UUCP messages | CRON -- ^ Cron messages | AUTHPRIV -- ^ Private authentication messages | FTP -- ^ FTP messages | LOCAL0 -- ^ LOCAL0 through LOCAL7 are reserved for you to customize as you wish | LOCAL1 | LOCAL2 | LOCAL3 | LOCAL4 | LOCAL5 | LOCAL6 | LOCAL7 deriving (Eq, Show, Read) code_of_fac :: Facility -> Int code_of_fac f = case f of KERN -> 0 USER -> 1 MAIL -> 2 DAEMON -> 3 AUTH -> 4 SYSLOG -> 5 LPR -> 6 NEWS -> 7 UUCP -> 8 CRON -> 9 AUTHPRIV -> 10 FTP -> 11 LOCAL0 -> 16 LOCAL1 -> 17 LOCAL2 -> 18 LOCAL3 -> 19 LOCAL4 -> 20 LOCAL5 -> 21 LOCAL6 -> 22 LOCAL7 -> 23 makeCode :: Facility -> Priority -> Int makeCode fac pri = let faccode = code_of_fac fac pricode = code_of_pri pri in (faccode `shiftL` 3) .|. pricode {- | Options for 'openlog'. -} data Option = PID -- ^ Automatically log process ID (PID) with each message | PERROR -- ^ Send a copy of each message to stderr deriving (Eq,Show,Read) data SyslogHandler = SyslogHandler {options :: [Option], facility :: Facility, identity :: String, logsocket :: Socket, address :: SockAddr, priority :: Priority, formatter :: LogFormatter SyslogHandler } {- | Initialize the Syslog system using the local system's default interface, \/dev\/log. Will return a new 'System.Log.Handler.LogHandler'. On Windows, instead of using \/dev\/log, this will attempt to send UDP messages to something listening on the syslog port (514) on localhost. Use 'openlog_remote' if you need more control. -} openlog :: String -- ^ The name of this program -- will be prepended to every log message -> [Option] -- ^ A list of 'Option's. The list [] is perfectly valid. ['PID'] is probably most common here. -> Facility -- ^ The 'Facility' value to pass to the syslog system for every message logged -> Priority -- ^ Messages logged below this priority will be ignored. To include every message, set this to 'DEBUG'. -> IO SyslogHandler -- ^ Returns the new handler #ifdef mingw32_HOST_OS openlog = openlog_remote AF_INET "localhost" 514 #elif darwin_HOST_OS openlog = openlog_local "/var/run/syslog" #else openlog = openlog_local "/dev/log" #endif {- | Initialize the Syslog system using an arbitrary Unix socket (FIFO). Not supported under Windows. -} #ifndef mingw32_HOST_OS openlog_local :: String -- ^ Path to FIFO -> String -- ^ Program name -> [Option] -- ^ 'Option's -> Facility -- ^ Facility value -> Priority -- ^ Priority limit -> IO SyslogHandler openlog_local fifopath ident options fac pri = do s <- socket AF_UNIX Datagram 0 openlog_generic s (SockAddrUnix fifopath) ident options fac pri #endif {- | Log to a remote server via UDP. -} openlog_remote :: Family -- ^ Usually AF_INET or AF_INET6; see Network.Socket -> HostName -- ^ Remote hostname. Some use @localhost@ -> PortNumber -- ^ 514 is the default for syslog -> String -- ^ Program name -> [Option] -- ^ 'Option's -> Facility -- ^ Facility value -> Priority -- ^ Priority limit -> IO SyslogHandler openlog_remote fam hostname port ident options fac pri = do he <- getHostByName hostname s <- socket fam Datagram 0 let addr = SockAddrInet port (head (hostAddresses he)) openlog_generic s addr ident options fac pri {- | The most powerful initialization mechanism. Takes an open datagram socket. -} openlog_generic :: Socket -- ^ A datagram socket -> SockAddr -- ^ Address for transmissions -> String -- ^ Program name -> [Option] -- ^ 'Option's -> Facility -- ^ Facility value -> Priority -- ^ Priority limit -> IO SyslogHandler openlog_generic sock addr ident opt fac pri = return (SyslogHandler {options = opt, facility = fac, identity = ident, logsocket = sock, address = addr, priority = pri, formatter = syslogFormatter }) syslogFormatter :: LogFormatter SyslogHandler syslogFormatter sh (p,msg) logname = let code = makeCode (facility sh) p getpid :: IO String getpid = #ifndef mingw32_HOST_OS getProcessID >>= return . show #else return "windows" #endif vars = [("code", return $ show code) ,("identity", return $ identity sh) ,("pid", getpid)] withPid = if (elem PID (options sh)) then "[$pid]" else "" format = "<$code>$identity"++withPid++": [$loggername/$prio] $msg" in varFormatter vars format sh (p,msg) logname instance LogHandler SyslogHandler where setLevel sh p = sh{priority = p} getLevel sh = priority sh setFormatter sh f = sh{formatter = f} getFormatter sh = formatter sh emit sh (_, msg) _ = let sendstr :: String -> IO String sendstr [] = return [] sendstr omsg = do sent <- sendTo (logsocket sh) omsg (address sh) sendstr (genericDrop sent omsg) in do if (elem PERROR (options sh)) then hPutStrLn stderr msg else return () sendstr (msg ++ "\0") return () close sh = sClose (logsocket sh)