Add curl-fu for logging in and retrieving pages.

diff --git a/src/LWN/HTTP.hs b/src/LWN/HTTP.hs
new file mode 100644 (file)
index 0000000..8b4c14d
--- /dev/null
+++ b/src/LWN/HTTP.hs
@@ -0,0 +1,120 @@
+module LWN.HTTP
+where
+
+import Network.Curl (
+  CurlCode(..),
+  CurlOption(..),
+  CurlResponse,
+  URLString,
+  do_curl_,
+  initialize,
+  respBody,
+  respCurlCode,
+  withCurlDo               
+  )
+import System.IO (hPutStrLn, stderr)
+
+login_url :: URLString
+login_url = "https://lwn.net/login"
+
+username_field :: String
+username_field = "Username"
+
+password_field :: String
+password_field = "Password"
+
+submit_field :: String
+submit_field = "submit"
+
+
+default_curl_opts :: [CurlOption]
+default_curl_opts =
+  [ -- The Global cache is not thread-friendly.
+    CurlDNSUseGlobalCache False,
+    
+    -- And we don't want to use a DNS cache anyway.
+    CurlDNSCacheTimeout 0,
+
+    -- Give it a little time...
+    CurlTimeout 45,
+
+    -- And let us know when things go wrong.
+    CurlVerbose True ]
+
+
+
+get_page :: Maybe FilePath -> URLString -> IO (Maybe String)
+get_page cookie_jar url =
+  withCurlDo $ do
+    -- Create a curl instance.
+    curl <- initialize
+
+    -- Perform the request, and get back a CurlResponse object.
+    -- The cast is needed to specify how we would like our headers
+    -- and body returned (Strings).
+    resp <- do_curl_ curl login_url curl_opts :: IO CurlResponse
+
+    -- Pull out the response code as a CurlCode.
+    let code = respCurlCode resp
+
+    case code of
+      CurlOK -> return $ Just (respBody resp)
+      error_code -> do
+        hPutStrLn stderr ("HTTP Error: " ++ (show error_code))
+        -- If an error occurred, we want to dump as much information as
+        -- possible. If this becomes a problem, we can use respGetInfo to
+        -- query the response object for more information
+        return Nothing
+  where
+    get_opts =
+      case cookie_jar of
+        Nothing -> []
+        Just cookies -> [ CurlCookieJar cookies ]
+
+    curl_opts = default_curl_opts ++ get_opts
+
+
+log_in :: FilePath -> String -> String -> IO Bool
+log_in cookie_jar username password =
+  withCurlDo $ do
+    -- Create a curl instance.
+    curl <- initialize
+
+    -- Perform the request, and get back a CurlResponse object.
+    -- The cast is needed to specify how we would like our headers
+    -- and body returned (Strings).
+    resp <- do_curl_ curl login_url curl_opts :: IO CurlResponse
+
+    -- Pull out the response code as a CurlCode.
+    let code = respCurlCode resp
+
+    case code of
+      CurlOK -> return True
+      error_code -> do
+        hPutStrLn stderr ("HTTP Error: " ++ (show error_code))
+        -- If an error occurred, we want to dump as much information as
+        -- possible. If this becomes a problem, we can use respGetInfo to
+        -- query the response object for more information
+        return False
+  where
+    post_submit :: String
+    post_submit = submit_field ++ "=Log+In"
+
+    post_username :: String
+    post_username = username_field ++ "=" ++ username
+
+    post_password :: String
+    post_password = password_field ++ "=" ++ password
+
+    post_data :: [String]
+    post_data = [post_username, post_password]
+
+    post_opts :: [CurlOption]
+    post_opts =
+      [ CurlCookieSession True,
+        CurlCookieJar cookie_jar,
+        CurlPost True,
+        CurlPostFields post_data ]
+        
+    curl_opts :: [CurlOption]
+    curl_opts = default_curl_opts ++ post_opts