{-# OPTIONS_GHC -fallow-overlapping-instances #-} ----------------------------------------------------------------------------- -- | -- Module : Network.CGI -- Copyright : (c) The University of Glasgow 2001 -- (c) Bjorn Bringert 2004-2006 -- (c) Ian Lynagh 2005 -- (c) Jeremy Shaw 2005 -- License : BSD-style -- -- Maintainer : Anders Kaseorg <andersk@mit.edu> -- Stability : experimental -- Portability : non-portable (uses Control.Monad.State) -- -- Simple Library for writing CGI programs. -- See <http://hoohoo.ncsa.uiuc.edu/cgi/interface.html> for the -- CGI specification. -- -- This version of the library is for systems with version 2.0 or greater -- of the network package. This includes GHC 6.6 and later. For older -- systems, see <http://www.cs.chalmers.se/~bringert/darcs/cgi-compat/doc/> -- -- Based on the original Haskell binding for CGI: -- -- Original Version by Erik Meijer <mailto:erik@cs.ruu.nl>. -- Further hacked on by Sven Panne <mailto:sven.panne@aedion.de>. -- Further hacking by Andy Gill <mailto:andy@galconn.com>. -- A new, hopefully more flexible, interface -- and support for file uploads by Bjorn Bringert <mailto:bjorn@bringert.net>. -- -- Here is a simple example, including error handling (not that there is -- much that can go wrong with Hello World): -- -- > import Network.CGI -- > -- > cgiMain :: CGI CGIResult -- > cgiMain = output "Hello World!" -- > -- > main :: IO () -- > main = runCGI (handleErrors cgiMain) -- -- ----------------------------------------------------------------------------- module Network.CGI ( -- * CGI monad MonadCGI, CGIT, CGIResult, CGI , MonadIO, liftIO , runCGI -- * Error handling , throwCGI, catchCGI, tryCGI, handleExceptionCGI , handleErrors -- * Logging , logCGI -- * Output , output, outputFPS, outputNothing, redirect , setHeader, setStatus -- * Error pages , outputError, outputException , outputNotFound, outputMethodNotAllowed, outputInternalServerError -- * Input , getInput, getInputFPS, readInput , getBody, getBodyFPS , getInputs, getInputsFPS, getInputNames , getMultiInput, getMultiInputFPS , getInputFilename, getInputContentType -- * Environment , getVar, getVarWithDefault, getVars -- * Request information , serverName, serverPort , requestMethod, pathInfo , pathTranslated, scriptName , queryString , remoteHost, remoteAddr , authType, remoteUser , requestContentType, requestContentLength , requestHeader -- * Program and request URI , progURI, queryURI, requestURI -- * Content negotiation , Acceptable, Accept , Charset(..), ContentEncoding(..), Language(..) , requestAccept, requestAcceptCharset, requestAcceptEncoding, requestAcceptLanguage , negotiate -- * Content type , ContentType(..), showContentType, parseContentType -- * Cookies , Cookie(..), newCookie , getCookie, readCookie , setCookie, deleteCookie -- * URL encoding , formEncode, urlEncode, formDecode, urlDecode -- * Compatibility with the old API , module Network.CGI.Compat ) where import Control.Exception.Extensible (Exception(..), SomeException, ErrorCall(..)) import Control.Monad (liftM) import Control.Monad.CatchIO (MonadCatchIO) import Control.Monad.Trans (MonadIO, liftIO) import Data.Char (toUpper) import Data.List (intersperse, sort, group) import Data.Maybe (fromMaybe) import qualified Data.Map as Map import Network.URI (URI(..), URIAuth(..), nullURI, parseRelativeReference, escapeURIString, isUnescapedInURI) import System.IO (stdin, stdout) import qualified Data.ByteString.Lazy.Char8 as BS import Data.ByteString.Lazy.Char8 (ByteString) import Network.CGI.Cookie (Cookie(..), showCookie, newCookie, findCookie) import qualified Network.CGI.Cookie as Cookie (deleteCookie) import Network.CGI.Accept import Network.CGI.Header import Network.CGI.Monad import Network.CGI.Protocol import Network.CGI.Compat import Text.XHtml (renderHtml, header, (<<), thetitle, (+++), body, h1, paragraph, hr, address) -- | Run a CGI action. Typically called by the main function. -- Reads input from stdin and writes to stdout. Gets -- CGI environment variables from the program environment. runCGI :: MonadIO m => CGIT m CGIResult -> m () runCGI f = do env <- getCGIVars hRunCGI env stdin stdout (runCGIT f) -- -- * Output \/ redirect -- -- | Output a 'String'. The output is assumed to be text\/html, encoded using -- ISO-8859-1. To change this, set the Content-type header using -- 'setHeader'. output :: MonadCGI m => String -- ^ The string to output. -> m CGIResult output = return . CGIOutput . BS.pack -- | Output a 'ByteString'. The output is assumed to be text\/html, -- encoded using ISO-8859-1. To change this, set the -- Content-type header using 'setHeader'. outputFPS :: MonadCGI m => ByteString -- ^ The string to output. -> m CGIResult outputFPS = return . CGIOutput -- | Do not output anything (except headers). outputNothing :: MonadCGI m => m CGIResult outputNothing = return CGINothing -- | Redirect to some location. redirect :: MonadCGI m => String -- ^ A URL to redirect to. -> m CGIResult redirect url = do setHeader "Location" url outputNothing -- -- * Error handling -- -- | Catches any exception thrown by the given CGI action, -- returns an error page with a 500 Internal Server Error, -- showing the exception information, and logs the error. -- -- Typical usage: -- -- > cgiMain :: CGI CGIResult -- > cgiMain = ... -- > -- > main :: IO () -- > main = runCGI (handleErrors cgiMain) handleErrors :: (MonadCGI m, MonadCatchIO m) => m CGIResult -> m CGIResult handleErrors = flip catchCGI outputException -- -- * Error output -- -- | Output a 500 Internal Server Error with information from -- an 'Exception'. outputException :: (MonadCGI m,MonadIO m) => SomeException -> m CGIResult outputException e = outputInternalServerError es where es = case fromException e of Just (ErrorCall msg) -> [msg] _ -> [show e] -- | Output an error page to the user, with the given -- HTTP status code in the response. Also logs the error information -- using 'logCGI'. outputError :: (MonadCGI m, MonadIO m) => Int -- ^ HTTP Status code -> String -- ^ Status message -> [String] -- ^ Error information -> m CGIResult outputError c m es = do logCGI $ show (c,m,es) setStatus c m let textType = ContentType "text" "plain" [("charset","ISO-8859-1")] htmlType = ContentType "text" "html" [("charset","ISO-8859-1")] cts <- liftM (negotiate [htmlType,textType]) requestAccept case cts of ct:_ | ct == textType -> do setHeader "Content-type" (showContentType textType) text <- errorText c m es output text _ -> do setHeader "Content-type" (showContentType htmlType) page <- errorPage c m es output $ renderHtml page -- | Create an HTML error page. errorPage :: MonadCGI m => Int -- ^ Status code -> String -- ^ Status message -> [String] -- ^ Error information -> m Html errorPage c m es = do server <- getVar "SERVER_SOFTWARE" host <- getVar "SERVER_NAME" port <- getVar "SERVER_PORT" let tit = show c ++ " " ++ m sig = "Haskell CGI" ++ " on " ++ fromMaybe "" server ++ " at " ++ fromMaybe "" host ++ maybe "" (", port "++) port return $ header << thetitle << tit +++ body << (h1 << tit +++ map (paragraph <<) es +++ hr +++ address << sig) errorText :: MonadCGI m => Int -- ^ Status code -> String -- ^ Status message -> [String] -- ^ Error information -> m String errorText c m es = return $ unlines $ (show c ++ " " ++ m) : es -- -- * Specific HTTP errors -- -- | Use 'outputError' to output and log a 404 Not Found error. outputNotFound :: (MonadIO m, MonadCGI m) => String -- ^ The name of the requested resource. -> m CGIResult outputNotFound r = outputError 404 "Not Found" ["The requested resource was not found: " ++ r] -- | Use 'outputError' to output and log a 405 Method Not Allowed error. outputMethodNotAllowed :: (MonadIO m, MonadCGI m) => [String] -- ^ The allowed methods. -> m CGIResult outputMethodNotAllowed ms = do let allow = concat $ intersperse ", " ms setHeader "Allow" allow outputError 405 "Method Not Allowed" ["Allowed methods : " ++ allow] -- | Use 'outputError' to output and log a 500 Internal Server Error. outputInternalServerError :: (MonadIO m, MonadCGI m) => [String] -- ^ Error information. -> m CGIResult outputInternalServerError es = outputError 500 "Internal Server Error" es -- -- * Environment variables -- -- | Get the value of a CGI environment variable. Example: -- -- > remoteAddr <- getVar "REMOTE_ADDR" getVar :: MonadCGI m => String -- ^ The name of the variable. -> m (Maybe String) getVar name = liftM (Map.lookup name) $ cgiGet cgiVars getVarWithDefault :: MonadCGI m => String -- ^ The name of the variable. -> String -- ^ Default value -> m String getVarWithDefault name def = liftM (fromMaybe def) $ getVar name -- | Get all CGI environment variables and their values. getVars :: MonadCGI m => m [(String,String)] getVars = liftM Map.toList $ cgiGet cgiVars -- -- * Request information -- -- | The server\'s hostname, DNS alias, or IP address as it would -- appear in self-referencing URLs. serverName :: MonadCGI m => m String serverName = getVarWithDefault "SERVER_NAME" "" -- | The port number to which the request was sent. serverPort :: MonadCGI m => m Int serverPort = liftM (fromMaybe 80 . (>>= maybeRead)) (getVar "SERVER_PORT") -- | The method with which the request was made. -- For HTTP, this is \"GET\", \"HEAD\", \"POST\", etc. requestMethod :: MonadCGI m => m String requestMethod = getVarWithDefault "REQUEST_METHOD" "GET" -- | The extra path information, as given by the client. -- This is any part of the request path that follows the -- CGI program path. -- If the string returned by this function is not empty, -- it is guaranteed to start with a @\'\/\'@. -- -- Note that this function returns an unencoded string. -- Make sure to percent-encode any characters -- that are not allowed in URI paths before using the result of -- this function to construct a URI. -- See 'progURI', 'queryURI' and 'requestURI' for a higher-level -- interface. pathInfo :: MonadCGI m => m String pathInfo = liftM slash $ getVarWithDefault "PATH_INFO" "" where slash s = if not (null s) && head s /= '/' then '/':s else s -- | The path returned by 'pathInfo', but with virtual-to-physical -- mapping applied to it. pathTranslated :: MonadCGI m => m String pathTranslated = getVarWithDefault "PATH_TRANSLATED" "" -- | A virtual path to the script being executed, -- used for self-referencing URIs. -- -- Note that this function returns an unencoded string. -- Make sure to percent-encode any characters -- that are not allowed in URI paths before using the result of -- this function to construct a URI. -- See 'progURI', 'queryURI' and 'requestURI' for a higher-level -- interface. scriptName :: MonadCGI m => m String scriptName = getVarWithDefault "SCRIPT_NAME" "" -- | The information which follows the ? in the URL which referenced -- this program. This is the percent-encoded query information. -- For most normal uses, 'getInput' and friends are probably -- more convenient. queryString :: MonadCGI m => m String queryString = getVarWithDefault "QUERY_STRING" "" -- | The hostname making the request. If the server does not have -- this information, Nothing is returned. See also 'remoteAddr'. remoteHost :: MonadCGI m => m (Maybe String) remoteHost = getVar "REMOTE_HOST" -- | The IP address of the remote host making the request. remoteAddr :: MonadCGI m => m String remoteAddr = getVarWithDefault "REMOTE_ADDR" "" -- | If the server supports user authentication, and the script is -- protected, this is the protocol-specific authentication method -- used to validate the user. authType :: MonadCGI m => m (Maybe String) authType = getVar "AUTH_TYPE" -- | If the server supports user authentication, and the script is -- protected, this is the username they have authenticated as. remoteUser :: MonadCGI m => m (Maybe String) remoteUser = getVar "REMOTE_USER" -- | For queries which have attached information, such as -- HTTP POST and PUT, this is the content type of the data. -- You can use 'parseContentType' to get a structured -- representation of the the content-type value. requestContentType :: MonadCGI m => m (Maybe String) requestContentType = getVar "CONTENT_TYPE" -- | For queries which have attached information, such as -- HTTP POST and PUT, this is the length of the content -- given by the client. requestContentLength :: MonadCGI m => m (Maybe Int) requestContentLength = liftM (>>= maybeRead) $ getVar "CONTENT_LENGTH" -- | Gets the value of the request header with the given name. -- The header name is case-insensitive. -- Example: -- -- > requestHeader "User-Agent" requestHeader :: MonadCGI m => String -> m (Maybe String) requestHeader name = getVar var where var = "HTTP_" ++ map toUpper (replace '-' '_' name) -- -- * Content negotiation -- requestHeaderValue :: (MonadCGI m, HeaderValue a) => String -> m (Maybe a) requestHeaderValue h = liftM (>>= parseM parseHeaderValue h) $ requestHeader h requestAccept :: MonadCGI m => m (Maybe (Accept ContentType)) requestAccept = requestHeaderValue "Accept" requestAcceptCharset :: MonadCGI m => m (Maybe (Accept Charset)) requestAcceptCharset = requestHeaderValue "Accept-Charset" requestAcceptEncoding :: MonadCGI m => m (Maybe (Accept ContentEncoding)) requestAcceptEncoding = requestHeaderValue "Accept-Encoding" requestAcceptLanguage :: MonadCGI m => m (Maybe (Accept Language)) requestAcceptLanguage = requestHeaderValue "Accept-Language" -- -- * Program and request URI -- -- | Attempts to reconstruct the absolute URI of this program. -- This does not include -- any extra path information or query parameters. See -- 'queryURI' for that. -- If the server is rewriting request URIs, this URI can -- be different from the one requested by the client. -- See also 'requestURI'. -- -- Characters in the components of the returned URI are escaped -- when needed, as required by "Network.URI". progURI :: MonadCGI m => m URI progURI = do -- Use HTTP_HOST if available, otherwise SERVER_NAME h <- requestHeader "Host" >>= maybe serverName return p <- serverPort name <- scriptName https <- liftM (maybe False (const True)) (getVar "HTTPS") -- SERVER_PORT might not be the port that the client used -- if the server listens on multiple ports, so we give priority -- to the port in HTTP_HOST. -- HTTP_HOST should include the port according to RFC2616 sec 14.23 -- Some servers (e.g. lighttpd) also seem to include the port in -- SERVER_NAME. -- We include the port if it is in HTTP_HOST or SERVER_NAME, or if -- it is a non-standard port. let (host,port) = case break (==':') h of (_,"") -> (h, if (not https && p == 80) || (https && p == 443) then "" else ':':show p) (h',p') -> (h',p') let auth = URIAuth { uriUserInfo = "", uriRegName = host, uriPort = port } return $ nullURI { uriScheme = if https then "https:" else "http:", uriAuthority = Just auth, uriPath = escapePath name } -- | Like 'progURI', but the returned 'URI' also includes -- any extra path information, and any query parameters. -- If the server is rewriting request URIs, this URI can -- be different from the one requested by the client. -- See also 'requestURI'. -- -- Characters in the components of the returned URI are escaped -- when needed, as required by "Network.URI". queryURI :: MonadCGI m => m URI queryURI = do uri <- progURI path <- pathInfo qs <- liftM (\q -> if null q then q else '?':q) $ queryString return $ uri { uriPath = uriPath uri ++ escapePath path, uriQuery = qs } -- | Does percent-encoding as needed for URI path components. escapePath :: String -> String escapePath = escapeURIString isUnescapedInURIPath where isUnescapedInURIPath c = isUnescapedInURI c && c `notElem` "?#" -- | Attempts to reconstruct the absolute URI requested by the client, -- including extra path information and query parameters. -- If no request URI rewriting is done, or if the web server does not -- provide the information needed to reconstruct the request URI, -- this function returns the same value as 'queryURI'. -- -- Characters in the components of the returned URI are escaped -- when needed, as required by "Network.URI". requestURI :: MonadCGI m => m URI requestURI = do uri <- queryURI -- Apache sets REQUEST_URI to the original request URI, -- with percent-encoding intact. mreq <- liftM (>>= parseRelativeReference) $ getVar "REQUEST_URI" return $ case mreq of Nothing -> uri Just req -> uri { uriPath = uriPath req, uriQuery = uriQuery req } -- -- * Inputs -- -- | Get the value of an input variable, for example from a form. -- If the variable has multiple values, the first one is returned. -- Example: -- -- > query <- getInput "query" getInput :: MonadCGI m => String -- ^ The name of the variable. -> m (Maybe String) -- ^ The value of the variable, -- or Nothing, if it was not set. getInput = liftM (fmap BS.unpack) . getInputFPS -- | Like 'getInput', but returns a 'ByteString'. getInputFPS :: MonadCGI m => String -- ^ The name of the variable. -> m (Maybe ByteString) -- ^ The value of the variable, -- or Nothing, if it was not set. getInputFPS = liftM (fmap inputValue) . getInput_ -- | Get all the values of an input variable, for example from a form. -- This can be used to get all the values from form controls -- which allow multiple values to be selected. -- Example: -- -- > vals <- getMultiInput "my_checkboxes" getMultiInput :: MonadCGI m => String -- ^ The name of the variable. -> m [String] -- ^ The values of the variable, -- or the empty list if the variable was not set. getMultiInput = liftM (map BS.unpack) . getMultiInputFPS -- | Same as 'getMultiInput' but using 'ByteString's. getMultiInputFPS :: MonadCGI m => String -- ^ The name of the variable. -> m [ByteString] -- ^ The values of the variable, -- or the empty list if the variable was not set. getMultiInputFPS n = do is <- cgiGet cgiInputs return [inputValue v | (p,v) <- is, p == n] -- | Get the file name of an input. getInputFilename :: MonadCGI m => String -- ^ The name of the variable. -> m (Maybe String) -- ^ The file name corresponding to the -- input, if there is one. getInputFilename = liftM (>>= inputFilename) . getInput_ -- | Get the content-type of an input, if the input exists, e.g. "image\/jpeg". -- For non-file inputs, this function returns "text\/plain". -- You can use 'parseContentType' to get a structured -- representation of the the content-type value. getInputContentType :: MonadCGI m => String -- ^ The name of the variable. -> m (Maybe String) -- ^ The content type, formatted as a string. getInputContentType = liftM (fmap (showContentType . inputContentType)) . getInput_ -- | Same as 'getInput', but tries to read the value to the desired type. readInput :: (Read a, MonadCGI m) => String -- ^ The name of the variable. -> m (Maybe a) -- ^ 'Nothing' if the variable does not exist -- or if the value could not be interpreted -- at the desired type. readInput = liftM (>>= maybeRead) . getInput -- | Get the names and values of all inputs. -- Note: the same name may occur more than once in the output, -- if there are several values for the name. getInputs :: MonadCGI m => m [(String,String)] getInputs = do is <- cgiGet cgiInputs return [ (n, BS.unpack (inputValue i)) | (n,i) <- is ] -- | Get the names and values of all inputs. -- Note: the same name may occur more than once in the output, -- if there are several values for the name. getInputsFPS :: MonadCGI m => m [(String,ByteString)] getInputsFPS = do is <- cgiGet cgiInputs return [ (n, inputValue i) | (n,i) <- is ] -- | Get the names of all input variables. getInputNames :: MonadCGI m => m [String] getInputNames = (sortNub . map fst) `liftM` cgiGet cgiInputs where sortNub = map head . group . sort -- Internal stuff getInput_ :: MonadCGI m => String -> m (Maybe Input) getInput_ n = lookup n `liftM` cgiGet cgiInputs -- | Get the uninterpreted request body as a String getBody :: MonadCGI m => m String getBody = BS.unpack `liftM` cgiGet cgiRequestBody -- | Get the uninterpreted request body as lazy ByteString getBodyFPS :: MonadCGI m => m ByteString getBodyFPS = cgiGet cgiRequestBody -- -- * Cookies -- -- | Get the value of a cookie. getCookie :: MonadCGI m => String -- ^ The name of the cookie. -> m (Maybe String) -- ^ 'Nothing' if the cookie does not exist. getCookie name = liftM (>>= findCookie name) (getVar "HTTP_COOKIE") -- | Same as 'getCookie', but tries to read the value to the desired type. readCookie :: (Read a, MonadCGI m) => String -- ^ The name of the cookie. -> m (Maybe a) -- ^ 'Nothing' if the cookie does not exist -- or if the value could not be interpreted -- at the desired type. readCookie = liftM (>>= maybeRead) . getCookie -- | Set a cookie. setCookie :: MonadCGI m => Cookie -> m () setCookie = setHeader "Set-cookie" . showCookie -- | Delete a cookie from the client deleteCookie :: MonadCGI m => Cookie -> m () deleteCookie = setCookie . Cookie.deleteCookie -- -- * Headers -- -- | Add a response header. -- Example: -- -- > setHeader "Content-type" "text/plain" setHeader :: MonadCGI m => String -- ^ Header name. -> String -- ^ Header value. -> m () setHeader n v = cgiAddHeader (HeaderName n) v -- | Set the HTTP response status. setStatus :: MonadCGI m => Int -- ^ HTTP status code, e.g. @404@ -> String -- ^ HTTP status message, e.g. @"Not Found"@ -> m () setStatus c m = setHeader "Status" (show c ++ " " ++ m)