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Affirmer understands and acknowledges that Creative Commons is not a + party to this document and has no duty or obligation with respect to + this CC0 or use of the Work. diff --git a/ChangeLog b/ChangeLog new file mode 100644 --- /dev/null +++ b/ChangeLog @@ -0,0 +1,17 @@ +The changes are recorded by the version control system, Darcs. To see a log +quickly from the terminal, run: + + $ darcs changes --repo http://dev.rel4tion.org/fr33domlover/http-listen + +There is also a web interface at which, among other +things, can display the history log. + +To see the log in a local clone, first get a copy of the repository if you +haven't yet: + + $ darcs get http://dev.rel4tion.org/fr33domlover/http-listen + +Then move into the newly created directory and run darcs: + + $ cd http-listen + $ darcs changes diff --git a/INSTALL b/INSTALL new file mode 100644 --- /dev/null +++ b/INSTALL @@ -0,0 +1,13 @@ +Install from Hackage: + + $ cabal install http-listen + +Install from unpacked release tarball or source repo: + + $ cd http-listen + $ cabal install + +Just play with it without installing: + + $ cabal build + $ cabal repl diff --git a/NEWS b/NEWS new file mode 100644 --- /dev/null +++ b/NEWS @@ -0,0 +1,23 @@ +This file lists the user-visible interesting changes between releases. For a +full list of changes to the source, see the ChangeLog. + + + +http-listen 0.1.0.0 -- 2015-08-06 +================================= + +General, build and documentation changes: + +* (This is the first release, so everything is new) + +New APIs, features and enhancements: + +* (This is the first release, so everything is a new feature) + +Bug fixes: + +* (This is just the first release) + +Dependency changes: + +* (This is the first release) diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,14 @@ +See the .cabal file for more info and link to project website the version +control. + +The official download location is Hackage: + + + +This library is free software, and is committed to software freedom. It is +released to the public domain using the CC0 Public Domain Dedication. For the +boring "legal" details see the file 'COPYING'. + +See the file 'INSTALL' for hints on installation. The file 'ChangeLog' explains +how to see the history log of the changes done in the code. 'NEWS' provides a +friendly overview of the changes for each release. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/http-listen.cabal b/http-listen.cabal new file mode 100644 --- /dev/null +++ b/http-listen.cabal @@ -0,0 +1,52 @@ +name: http-listen +version: 0.1.0.0 +synopsis: Listen to HTTP requests and handle them in arbitrary ways. +description: + In HTTP connections, there is a client side which sends requests (such as GET + and POST), and a server side which receives and parses them. Often, the + server side is a web server which responds to requests by sending some HTML + pages back. But sometimes it's just a listener. + . + For example, a Git server may offer web hooks. It could send a POST request + whenever a commit is made, or a new repository is created. You then set up a + program that listens to these POSTs and reacts by reporting them to the + project's IRC channel or a mailing list. + . + Most HTTP packages assume a typical web server which handles requests by + returning HTTP responses. This package tries to fill a gap by providing an + API for simple listeners which don't necessarily serve web pages, and can do + things like reporting to IRC. + . + Some features are missing and will be added soon: + . + * Connection timeouts + * Logging (currently errors are written to stdout, no other logging done) +homepage: http://rel4tion.org/projects/http-listen/ +bug-reports: http://rel4tion.org/projects/http-listen/tickets/ +license: PublicDomain +license-file: COPYING +author: fr33domlover +maintainer: fr33domlover@riseup.net +copyright: ♡ Copying is an act of love. Please copy, reuse and share. +category: Network, Web +build-type: Simple +extra-source-files: AUTHORS ChangeLog COPYING INSTALL NEWS README.md +cabal-version: >=1.10 + +source-repository head + type: darcs + location: http://dev.rel4tion.org/fr33domlover/http-listen + +library + exposed-modules: Network.HTTP.Listen + -- other-modules: + -- other-extensions: + build-depends: base >=4.7 && <5 + , bytestring + , exceptions >=0.8 + --, fast-logger >=2.4 + , HTTP >=4000.2 + , network + , transformers >=0.4.1 + hs-source-dirs: src + default-language: Haskell2010 diff --git a/src/Network/HTTP/Listen.hs b/src/Network/HTTP/Listen.hs new file mode 100644 --- /dev/null +++ b/src/Network/HTTP/Listen.hs @@ -0,0 +1,542 @@ +{- This file is part of http-listen. + - + - Written in 2015 by fr33domlover . + - + - ♡ Copying is an act of love. Please copy, reuse and share. + - + - The author(s) have dedicated all copyright and related and neighboring + - rights to this software to the public domain worldwide. This software is + - distributed without any warranty. + - + - You should have received a copy of the CC0 Public Domain Dedication along + - with this software. If not, see + - . + -} + +-- | This module offers several ways to create an HTTP listener, hopefully +-- covering common use cases. They are described below, from high level to low +-- level. But before that, here's a quick start example. +-- +-- = Quickstart +-- +-- Create a source file containing the following: +-- +-- > import qualified Data.ByteString.Lazy as B +-- > import Network.HTTP +-- > import Network.HTTP.Listen +-- > +-- > listener :: Listener B.ByteString IO +-- > listener request = print request >> return Nothing +-- > +-- > main :: IO +-- > main = run 8999 listener +-- +-- Install the http-listen package from Hackage: +-- +-- > $ cabal install http-listen +-- +-- Run the program: +-- +-- > $ runhaskell hello.hs +-- +-- Now point your web browser to @http://localhost:8999@. It will fail to load +-- anything, since our listener doesn't send any response, but in the terminal +-- you'll see the HTTP request printed. +-- +-- = Running a Listener +-- +-- A 'Listener' is a function which takes an HTTP request and returns an action +-- in some monad @m@. Since receiving HTTP requests is an IO activity, @m@ must +-- be a 'MonadIO' instance. For example, the 'IO' monad itself, or a monad +-- transformer stack on top of 'IO'. +-- +-- The IO action optionally returns an HTTP response, which is then sent back +-- to the client. Setting up the headers of the response, and in particular the +-- @connection@ header (which affects HTTP connection persistence), are up to +-- the listener. The library decides based on it (and based on the request) +-- whether to close the connection or keep it open. If you don't need to send +-- anything back to the client, just write your listener function to return +-- 'Nothing'. +-- +-- A 'Listener' handles requests with content encoded into a specific type. +-- That type must be an instance of 'HStream' (a class from the HTTP package). +-- The HTTP package provides instances for 'String' and for strict and lazy +-- bytestrings. You can write your own instances, but in most cases you +-- probably won't need to. Perhaps instances for 'Data.Text.Text' and its lazy +-- version could be useful. +-- +-- Here is an example listener, which takes requests containing lazy +-- 'Data.ByteString.Lazy.ByteString' data, and returns an 'IO' action. All it +-- does is print the HTTP request it got into standard output. +-- +-- > import qualified Data.ByteString.Lazy as B +-- > import Network.HTTP +-- > import Network.HTTP.Listen +-- > +-- > listener :: Listener B.ByteString IO +-- > listener request = do +-- > print request +-- > return Nothing +-- +-- Once we've defined the listener, we can run a loop which listens to TCP +-- connections, reads HTTP responses from them and applies our listener +-- function. There are two ready functions which run such a loop, 'run' and +-- 'runWithBlocking'. The difference is that 'run' handles each connection in +-- a separate thread (using 'forkIO'), while 'runWithBlocking' does everything +-- in a single thread. +-- +-- Both functions take 2 parameters. A port number and the listener function. +-- For example, run our listener on port 8999 like this: +-- +-- > run 8999 listener +-- +-- Another difference between blocking and non-blocking runs, is that blocking +-- runs support listeners operating in any instance of 'MonadIO' and +-- 'C.MonadMask', while non-blocking ones are IO only. This may seem like a +-- restriction, but it actually makes sense: When using a single thread, you +-- can use some monad transformer stack with state and logging and other +-- effects. When forking to a new thread on each connection, you don't use or +-- need any extra effects because the logic happens in a separate thread. In +-- that separate thread you can use whatever monad(s) you wish. +-- +-- On the technical side, 'forkIO' takes an IO action of type @IO ()@, so +-- that's what the non-blocking run needs to use. +-- +-- = Handling Clients +-- +-- To get a bit more control, you can write your own (blocking or non-blocking) +-- client handling loop. The primary components are: +-- +-- * 'prepareSocket' opens a server socket listening to connections +-- * 'handleClient' handles a client connection in a new thread +-- * 'handleClientBlocking' is a version that runs in the current thread +-- +-- There are a few more utility functions you may find useful. +-- +-- Let's write a simple loop which accepts connections from clients and handles +-- them in separate worker threads which apply our listener. We'll use the same +-- listener from the previous section. +-- +-- > listener :: Listener B.ByteString IO +-- > listener request = { ... same as above .... } +-- > +-- > main = +-- > bracket +-- > (prepareSocket 8999) +-- > close +-- > (\ sock -> forever $ handleClient sock listener) +-- +-- = Manual Control +-- +-- This is the lowest level layer provided by this module. It wraps the +-- relevant parts of the @network@ and @HTTP@ packages, creating a network API +-- for web listeners. It may be useful if you need more flexibility that the +-- higher level layers can provide. +-- +-- Let's write a simple program using this API, which handles a single +-- connection and exits. For simplicity, we'll assume a single HTTP request is +-- received per connection, so we'll close the connection after getting one +-- request. In reality, connections can be used for sending multiple requests +-- (in HTTP 1.1, connection reuse is the default behavior). +-- +-- As usual, we begin by preparing a server socket: +-- +-- > main :: IO () +-- > main = do +-- > sock <- prepareSocket 8999 +-- > -- ... +-- +-- Then we wait for a connection from a client: +-- +-- > main = do +-- > sock <- prepareSocket 8999 +-- > conn <- acceptConnection sock +-- > -- ... +-- +-- Once we have a connection, we open a stream for receiving data. After +-- opening a stream successfully, we don't need the connection value anymore +-- (the stream value is now holding the newly open socket). +-- +-- Opening a stream and further actions could happen in a separate thread, so +-- that all the main thread does is accept connections. For simplicity, let's +-- just do this in the same thread. +-- +-- > main = do +-- > sock <- prepareSocket 8999 +-- > conn <- acceptConnection sock +-- > stream <- openStream conn +-- > -- ... +-- +-- Now we can read an HTTP request from the client: +-- +-- > main = do +-- > sock <- prepareSocket 8999 +-- > conn <- acceptConnection sock +-- > stream <- openStream conn +-- > result <- receiveRequest stream +-- > -- ... +-- +-- Since we're done with the connection, let's close the stream. We're also +-- done accepting connections, so let's close the server socket too. +-- +-- > main = do +-- > sock <- prepareSocket 8999 +-- > conn <- acceptConnection sock +-- > stream <- openStream conn +-- > result <- receiveRequest stream +-- > closeStream stream +-- > close sock +-- > -- ... +-- +-- Finally, let's display what we got: +-- +-- > main = do +-- > sock <- prepareSocket 8999 +-- > conn <- acceptConnection sock +-- > stream <- openStream conn +-- > result <- receiveRequest stream +-- > closeStream stream +-- > close sock +-- > case result of +-- > Left err -> print err +-- > Right (request :: Request B.ByteString) -> print request +-- +-- This is of course over simplified. We didn't consider connection +-- persistence. We should probably handle exceptions here to make sure the +-- sockets are safely closed even in case of error, e.g. using 'bracket'. We +-- could also use a timeout to avoid accumulating unused connections. But all +-- of that can be done on top of the basics shown above, or using the higher +-- level APIs. +module Network.HTTP.Listen + ( -- * Basics + Connection () + , Stream () + , prepareSocket + , acceptConnection + , openStream + , receiveRequest + , sendResponse + , closeStream + , closeConnection + -- * Utilities + , HttpVersion (..) + , parseHttpVersion + , HasHttpVersion (..) + , httpVersion' + , reqPersist + , respPersist + , persist + , pipelined + -- * Client Handling + , Listener + , listenerNull + , listenerPrint + , listenerPong + , handleRequest + , handleClient + , handleClientBlocking + -- * Running + , run + , runWithBlocking + ) +where + +import Control.Concurrent (forkIO) +import Control.Exception (bracket) +import Control.Monad (forever, void, when) +import qualified Control.Monad.Catch as C +import Control.Monad.IO.Class +import qualified Data.ByteString.Lazy as B +import qualified Data.ByteString.Lazy.Char8 as BC +import Data.Char (digitToInt, isDigit, toLower) +import Data.Maybe (fromMaybe) +import Network.HTTP hiding ( Connection + , openStream + , httpVersion + ) +import Network.Socket hiding (Stream) +import qualified Network.Socket as S (SocketType (Stream)) +import Network.Stream (Result) + +------------------------------------------------------------------------------- +-- Basics +------------------------------------------------------------------------------- + +-- | Handle to a connection from an HTTP client (technically, a TCP client in +-- general). +data Connection = Connection + { connSocket :: Socket + , connAddr :: SockAddr + } + +-- | A stream of data passing over a 'Connection'. +newtype Stream t = Stream { unStream :: HandleStream t } + +-- Represent a boolean as an integer, 0 or 1. +pseudoBool :: Integral a => Bool -> a +pseudoBool False = 0 +pseudoBool True = 1 + +-- | Initialize a server socket and start listening to connections from +-- clients. After calling this, the returned socket can accept connections. +prepareSocket :: Int -> IO Socket +prepareSocket port = do + let hints = defaultHints + { addrSocketType = S.Stream + , addrFlags = [AI_PASSIVE, AI_ADDRCONFIG] + } + addrs <- getAddrInfo (Just hints) Nothing (Just $ show port) + let addr = head addrs + sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr) + setSocketOption sock ReuseAddr (pseudoBool True) + bind sock (addrAddress addr) + listen sock maxListenQueue + return sock + +-- Get the address (for TCP, the IP address) of the client. +getHost :: SockAddr -> String +getHost = show + +-- Get the port of the open connection with the client. +getPort :: SockAddr -> Int +getPort (SockAddrInet port _) = fromIntegral port +getPort (SockAddrInet6 port _ _ _) = fromIntegral port +getPort (SockAddrUnix _) = -1 +getPort (SockAddrCan _) = -1 + +-- | Given an initialized server socket, wait for a connection from a client. +-- It can be called repeatedly, in a loop, by the main server thread to accept +-- all the incoming connections. +acceptConnection :: Socket -> IO Connection +acceptConnection sock = do + (csock, addr) <- accept sock + return $ Connection csock addr + +-- | Open a data stream over a connection. The stream holds the connection +-- state too, so after calling this function you don't need the 'Connection' +-- value anymore. +openStream :: HStream t => Connection -> IO (Stream t) +openStream (Connection csock addr) = do + s <- openSocketStream (getHost addr) (getPort addr) csock + return $ Stream s + +-- | Read an HTTP request from an open stream. +receiveRequest :: HStream t => Stream t -> IO (Result (Request t)) +receiveRequest = receiveHTTP . unStream + +-- | Send an HTTP response back to the client through the open stream. +sendResponse :: HStream t => Stream t -> Response t -> IO () +sendResponse = respondHTTP . unStream + +-- | Close an open stream. This closes the connection with the client. Don't +-- try to send or receive anything from the stream after closing it. +closeStream :: HStream t => Stream t -> IO () +closeStream = Network.HTTP.close . unStream + +-- | Close an open connection. Use this only if you want to close the +-- connection before opening a stream. If you opened a stream over the +-- connection, use 'closeStream' to close it. +closeConnection :: Connection -> IO () +closeConnection = Network.Socket.close . connSocket + +------------------------------------------------------------------------------- +-- Utilities +------------------------------------------------------------------------------- + +-- | An HTTP protocol version. +data HttpVersion = HttpVersion Int Int deriving Eq + +-- | A class for types which have an HTTP version. In other words, an HTTP +-- request or an HTTP response (but other instances are of course possible if +-- you need then for any reason). +class HasHttpVersion a where + httpVersion :: a -> Maybe HttpVersion + +-- | Parse an HTTP version string, e.g. @"HTTP/1.1"@, into an 'HttpVersion' +-- value. If the string isn't a valid version string, return 'Nothing'. +parseHttpVersion :: String -> Maybe HttpVersion +parseHttpVersion ['H', 'T', 'T', 'P', '/', ma, '.', mi] = + if isDigit ma && isDigit mi + then Just $ HttpVersion (digitToInt ma) (digitToInt mi) + else Nothing +parseHttpVersion _ = Nothing + +instance HasHttpVersion (Request t) where + httpVersion r = getRequestVersion r >>= parseHttpVersion + +instance HasHttpVersion (Response t) where + httpVersion r = getResponseVersion r >>= parseHttpVersion + +-- | This is like 'httpVersion', but returns a default version (currently HTTP +-- 1.0) if the no version is explicity specified. +httpVersion' :: HasHttpVersion r => r -> HttpVersion +httpVersion' r = fromMaybe (HttpVersion 1 0) $ httpVersion r + +-- Get value of the Connection header. +getConnHeader :: HasHeaders r => r -> Maybe String +getConnHeader = findHeader HdrConnection + +-- Like 'getConnHeader', but returns the value in lowercase. +getConnHeaderL :: HasHeaders r => r -> Maybe String +getConnHeaderL = fmap (map toLower) . getConnHeader + +-- Whether the object specifies Close in its Connection header. +hasClose :: HasHeaders r => r -> Bool +hasClose = maybe False (== "close") . getConnHeaderL + +-- Whether the object specifies Keep-Alive in its Connection header. +hasKeepAlive :: HasHeaders r => r -> Bool +hasKeepAlive = maybe False (== "keep-alive") . getConnHeaderL + +-- Whether a persistent connection is indicated by the headers and the version. +isPersistent' :: HasHeaders r => r -> HttpVersion -> Bool +isPersistent' r version = + if version == HttpVersion 1 1 + -- In HTTP 1.1 connections are persistent unless declared otherwise + then not $ hasClose r + -- Before HTTP 1.1 need to specify Keep-Alive + else hasKeepAlive r + +-- Whether a persistent connection is indicated. +isPersistent :: (HasHeaders r, HasHttpVersion r) => r -> Bool +isPersistent r = isPersistent' r (httpVersion' r) + +-- | Check whether the request indicates the connection should be persistent. +reqPersist :: Request t -> Bool +reqPersist = isPersistent + +-- | Check whether, assuming the request indicated a persistent connection, the +-- given response too indicates the connection should persist. +respPersist :: Response t -> Bool +respPersist = isPersistent + +-- | Check whether, given the request and its response, the connection should +-- persist (i.e. kept open after the response it sent). +persist :: Request t -> Response t -> Bool +persist q s = reqPersist q && respPersist s + +-- | Check whether the connection should be pipelined, i.e. whether the server +-- should allow the client to receive multiple requests without waiting for the +-- response every time. +pipelined :: Request t -> Bool +pipelined request = + let version = httpVersion' request + in version == HttpVersion 1 1 && isPersistent' request version + +------------------------------------------------------------------------------- +-- Handling Clients +------------------------------------------------------------------------------- + +-- | An HTTP listener application. It gets an HTTP request with a body encoded +-- as type @t@, and returns an 'IO' action to run in reaction to the request. +-- The action can optionally return an HTTP response, which will be sent back +-- to the client. +type Listener t m = Request t -> m (Maybe (Response t)) + +-- | This listener does nothing. Perhaps it can be useful for benchmarking. +-- Anyway, it's here for completeness. +listenerNull :: Listener B.ByteString IO +listenerNull _request = return Nothing + +-- | This listener prints the request details to the console (stdout). +listenerPrint :: Listener B.ByteString IO +listenerPrint request = print request >> return Nothing + +-- | This listener sends the message "It works!", and the request body if any, +-- back to the client. +listenerPong :: Listener B.ByteString IO +listenerPong request = return . Just $ Response + { rspCode = (2, 0, 0) + , rspReason = "OK" + , rspHeaders = + [ Header HdrContentType "text/plain; charset=UTF-8" + , Header HdrConnection "close" + ] + , rspBody = BC.pack "It works!\n\n" `B.append` rqBody request + } + +-- | Read a single request from the stream. If successful, apply the listener +-- function to it and send back a response if it returns one. Finally, return +-- whether the connection should persist ('True') or close ('False'). +handleRequest :: (HStream t, MonadIO m) => Stream t -> Listener t m -> m Bool +handleRequest s listener = do + result <- liftIO $ receiveRequest s + case result of + Left err -> do + liftIO $ putStrLn $ "Error: " ++ show err + return False + Right request -> do + mresp <- listener request + case mresp of + Just response -> do + liftIO $ sendResponse s response + return $ + isPersistent request && isPersistent response + Nothing -> return $ pipelined request + +-- Repeatedly read and handle requests, until it's time to close the +-- connection. +requestLoop :: (HStream t, MonadIO m) => Stream t -> Listener t m -> m () +requestLoop strm listener = loop strm + where + loop s = do + proceed <- handleRequest s listener + when proceed $ loop s + +-- Manage a connection with a client. +handleClient' :: (HStream t, MonadIO m) => Connection -> Listener t m -> m () +handleClient' conn listener = do + s <- liftIO $ openStream conn + requestLoop s listener + liftIO $ closeStream s + +-- | Wait for a connection from a client. When it arrives, fork to a new +-- thread. In that thread, receive HTTP requests and handle them using the +-- listener. Finally, close the connection. +handleClient :: HStream t + => Socket + -> Listener t IO + -> IO () +handleClient sock listener = do + conn <- acceptConnection sock + void $ forkIO $ handleClient' conn listener + +-- | Like 'handleClient', but run everything in the current thread instead of +-- forking to a new one. Note that the listener itself could launch actions in +-- new threads. +handleClientBlocking :: (HStream t, MonadIO m) + => Socket + -> Listener t m + -> m () +handleClientBlocking sock listener = do + conn <- liftIO $ acceptConnection sock + handleClient' conn listener + +------------------------------------------------------------------------------- +-- Running a Listener +------------------------------------------------------------------------------- + +-- | Run an HTTP listener. Open a server socket, listen to connections from +-- clients and handle them using the listener in separate worker threads. +run :: HStream t + => Int + -> Listener t IO + -> IO () +run port listener = + bracket + (prepareSocket port) + Network.Socket.close + (\ sock -> forever $ handleClient sock listener) + +-- | Like 'run', but does everything in the current thread instead of forking +-- to a new one. Note that the listener itself could launch actions in new +-- threads. +runWithBlocking :: (HStream t, MonadIO m, C.MonadMask m) + => Int + -> Listener t m + -> m () +runWithBlocking port listener = + C.bracket + (liftIO $ prepareSocket port) + (liftIO . Network.Socket.close) + (\ sock -> forever $ handleClientBlocking sock listener)