Extensions too!
[toast/cookiecaptcha.git] / ConfirmEdit.php
index ffb4abd510bfdaeda50c7cfc396739dd96fe601d..f6cab654887d27b3090be8f81473857806205b90 100644 (file)
@@ -1,17 +1,55 @@
 <?php
 
-# Prelim in-progress code. Proof of concept for framework, not
-# intended as a real production captcha system!
-
-# Loader for simple captcha feature
-# Include this from LocalSettings.php
+/**
+ * Experimental captcha plugin framework.
+ * Not intended as a real production captcha system; derived classes
+ * can extend the base to produce their fancy images in place of the
+ * text-based test output here.
+ *
+ * Copyright (C) 2005-2007 Brion Vibber <brion@wikimedia.org>
+ * http://www.mediawiki.org/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @addtogroup Extensions
+ */
 
 if ( defined( 'MEDIAWIKI' ) ) {
 
 global $wgExtensionFunctions, $wgGroupPermissions;
 
 $wgExtensionFunctions[] = 'ceSetup';
+$wgExtensionCredits['other'][] = array(
+       'name' => 'ConfirmEdit',
+       'author' => 'Brion Vibber',
+       'url' => 'http://www.mediawiki.org/wiki/Extension:ConfirmEdit',
+       'description' => 'Simple captcha implementation',
+);
+
+# Internationalisation file
+require_once( 'ConfirmEdit.i18n.php' );
 
+/**
+ * The 'skipcaptcha' permission key can be given out to
+ * let known-good users perform triggering actions without
+ * having to go through the captcha.
+ *
+ * By default, sysops and registered bot accounts will be
+ * able to skip, while others have to go through it.
+ */
 $wgGroupPermissions['*'            ]['skipcaptcha'] = false;
 $wgGroupPermissions['user'         ]['skipcaptcha'] = false;
 $wgGroupPermissions['autoconfirmed']['skipcaptcha'] = false;
@@ -22,9 +60,74 @@ global $wgCaptcha, $wgCaptchaClass, $wgCaptchaTriggers;
 $wgCaptcha = null;
 $wgCaptchaClass = 'SimpleCaptcha';
 
+/**
+ * Actions which can trigger a captcha
+ *
+ * If the 'edit' trigger is on, *every* edit will trigger the captcha.
+ * This may be useful for protecting against vandalbot attacks.
+ *
+ * If using the default 'addurl' trigger, the captcha will trigger on
+ * edits that include URLs that aren't in the current version of the page.
+ * This should catch automated linkspammers without annoying people when
+ * they make more typical edits.
+ *
+ * The captcha code should not use $wgCaptchaTriggers, but CaptchaTriggers()
+ * which also takes into account per namespace triggering.
+ */
 $wgCaptchaTriggers = array();
-$wgCaptchaTriggers['edit']   = false; // Would check on every edit
-$wgCaptchaTriggers['addurl'] = true;  // Check on edits that add URLs
+$wgCaptchaTriggers['edit']          = false; // Would check on every edit
+$wgCaptchaTriggers['create']           = false; // Check on page creation.
+$wgCaptchaTriggers['addurl']        = true;  // Check on edits that add URLs
+$wgCaptchaTriggers['createaccount'] = true;  // Special:Userlogin&type=signup
+$wgCaptchaTriggers['badlogin']      = true;  // Special:Userlogin after failure
+
+/**
+ * You may wish to apply special rules for captcha triggering on some namespaces.
+ * $wgCaptchaTriggersOnNamespace[<namespace id>][<trigger>] forces an always on / 
+ * always off configuration with that trigger for the given namespace.
+ * Leave unset to use the global options ($wgCaptchaTriggers).
+ *
+ * Shall not be used with 'createaccount' (it is not checked).
+ */
+$wgCaptchaTriggersOnNamespace = array();
+
+#Example:
+#$wgCaptchaTriggersOnNamespace[NS_TALK]['create'] = false; //Allow creation of talk pages without captchas.
+#$wgCaptchaTriggersOnNamespace[NS_PROJECT]['edit'] = true; //Show captcha whenever editing Project pages.
+
+/**
+ * Indicate how to store per-session data required to match up the
+ * internal captcha data with the editor.
+ *
+ * 'CaptchaSessionStore' uses PHP's session storage, which is cookie-based
+ * and may fail for anons with cookies disabled.
+ *
+ * 'CaptchaCacheStore' uses $wgMemc, which avoids the cookie dependency
+ * but may be fragile depending on cache configuration.
+ */
+global $wgCaptchaStorageClass;
+$wgCaptchaStorageClass = 'CaptchaSessionStore';
+
+/**
+ * Number of seconds a captcha session should last in the data cache
+ * before expiring when managing through CaptchaCacheStore class.
+ *
+ * Default is a half hour.
+ */
+global $wgCaptchaSessionExpiration;
+$wgCaptchaSessionExpiration = 30 * 60;
+
+/**
+ * Number of seconds after a bad login that a captcha will be shown to
+ * that client on the login form to slow down password-guessing bots.
+ *
+ * Has no effect if 'badlogin' is disabled in $wgCaptchaTriggers or
+ * if there is not a caching engine enabled.
+ *
+ * Default is five minutes.
+ */
+global $wgCaptchaBadLoginExpiration;
+$wgCaptchaBadLoginExpiration = 5 * 60;
 
 /**
  * Allow users who have confirmed their e-mail addresses to post
@@ -33,20 +136,61 @@ $wgCaptchaTriggers['addurl'] = true;  // Check on edits that add URLs
 global $ceAllowConfirmedEmail;
 $ceAllowConfirmedEmail = false;
 
+/**
+ * Regex to whitelist URLs to known-good sites...
+ * For instance:
+ * $wgCaptchaWhitelist = '#^https?://([a-z0-9-]+\\.)?(wikimedia|wikipedia)\.org/#i';
+ * Local admins can define a whitelist under [[MediaWiki:captcha-addurl-whitelist]]
+ */
+$wgCaptchaWhitelist = false;
+
+/**
+ * Additional regexes to check for. Use full regexes; can match things
+ * other than URLs such as junk edits.
+ *
+ * If the new version matches one and the old version doesn't,
+ * toss up the captcha screen.
+ *
+ * @fixme Add a message for local admins to add items as well.
+ */
+$wgCaptchaRegexes = array();
+
+/** Register special page */
+global $wgSpecialPages;
+$wgSpecialPages['Captcha'] = array( /*class*/ 'SpecialPage', /*name*/'Captcha', /*restriction*/ '',
+       /*listed*/ false, /*function*/ false, /*file*/ false );
+
 /**
  * Set up message strings for captcha utilities.
  */
 function ceSetup() {
-       global $wgMessageCache, $wgHooks, $wgCaptcha, $wgCaptchaClass;
-       $wgMessageCache->addMessage('captcha-short', "Your edit includes new URL links; as a protection
-               against automated spam, you'll need to enter the answer to this
-               simple arithmetic test:" );
-       
-       SpecialPage::addPage( new SpecialPage( 'Captcha', false,
-               /*listed*/ false, /*function*/ false, /*file*/ false ) );
-       
+       # Add messages
+       global $wgMessageCache, $wgConfirmEditMessages;
+       foreach( $wgConfirmEditMessages as $lang => $messages )
+               $wgMessageCache->addMessages( $messages, $lang );
+
+       global $wgHooks, $wgCaptcha, $wgCaptchaClass, $wgSpecialPages;
        $wgCaptcha = new $wgCaptchaClass();
        $wgHooks['EditFilter'][] = array( &$wgCaptcha, 'confirmEdit' );
+
+       $wgHooks['UserCreateForm'][] = array( &$wgCaptcha, 'injectUserCreate' );
+       $wgHooks['AbortNewAccount'][] = array( &$wgCaptcha, 'confirmUserCreate' );
+       
+       $wgHooks['LoginAuthenticateAudit'][] = array( &$wgCaptcha, 'triggerUserLogin' );
+       $wgHooks['UserLoginForm'][] = array( &$wgCaptcha, 'injectUserLogin' );
+       $wgHooks['AbortLogin'][] = array( &$wgCaptcha, 'confirmUserLogin' );
+       
+       global $wgGroupPermissions, $wgCaptchaTriggers;
+       if( !$wgGroupPermissions['*']['read'] && $wgCaptchaTriggers['badlogin'] ) {
+               // We need to ensure that the captcha interface is accessible
+               // so that unauthenticated users can actually get in after a
+               // mistaken password typing.
+               global $wgWhitelistRead;
+               $image = Title::makeTitle( NS_SPECIAL, 'Captcha/image' );
+               $help = Title::makeTitle( NS_SPECIAL, 'Captcha/help' );
+               $wgWhitelistRead[] = $image->getPrefixedText();
+               $wgWhitelistRead[] = $help->getPrefixedText();
+       }
 }
 
 /**
@@ -64,6 +208,177 @@ function wfSpecialCaptcha( $par = null ) {
 }
 
 class SimpleCaptcha {
+       function SimpleCaptcha() {
+               global $wgCaptchaStorageClass;
+               $this->storage = new $wgCaptchaStorageClass;
+       }
+       
+       /**
+        * Insert a captcha prompt into the edit form.
+        * This sample implementation generates a simple arithmetic operation;
+        * it would be easy to defeat by machine.
+        *
+        * Override this!
+        *
+        * @return string HTML
+        */
+       function getForm() {
+               $a = mt_rand(0, 100);
+               $b = mt_rand(0, 10);
+               $op = mt_rand(0, 1) ? '+' : '-';
+
+               $test = "$a $op $b";
+               $answer = ($op == '+') ? ($a + $b) : ($a - $b);
+
+               $index = $this->storeCaptcha( array( 'answer' => $answer ) );
+
+               return "<p><label for=\"wpCaptchaWord\">$test</label> = " .
+                       wfElement( 'input', array(
+                               'name' => 'wpCaptchaWord',
+                               'id'   => 'wpCaptchaWord',
+                               'tabindex' => 1 ) ) . // tab in before the edit textarea
+                       "</p>\n" .
+                       wfElement( 'input', array(
+                               'type'  => 'hidden',
+                               'name'  => 'wpCaptchaId',
+                               'id'    => 'wpCaptchaId',
+                               'value' => $index ) );
+       }
+
+       /**
+        * Insert the captcha prompt into an edit form.
+        * @param OutputPage $out
+        */
+       function editCallback( &$out ) {
+               $out->addWikiText( $this->getMessage( $this->action ) );
+               $out->addHTML( $this->getForm() );
+       }
+
+       /**
+        * Show a message asking the user to enter a captcha on edit
+        * The result will be treated as wiki text
+        *
+        * @param $action Action being performed
+        * @return string
+        */
+       function getMessage( $action ) {
+               $name = 'captcha-' . $action;
+               $text = wfMsg( $name );
+               # Obtain a more tailored message, if possible, otherwise, fall back to
+               # the default for edits
+               return wfEmptyMsg( $name, $text ) ? wfMsg( 'captcha-edit' ) : $text;
+       }
+
+       /**
+        * Inject whazawhoo
+        * @fixme if multiple thingies insert a header, could break
+        * @param SimpleTemplate $template
+        * @return bool true to keep running callbacks
+        */
+       function injectUserCreate( &$template ) {
+               global $wgCaptchaTriggers, $wgOut;
+               if( $wgCaptchaTriggers['createaccount'] ) {
+                       $template->set( 'header',
+                               "<div class='captcha'>" .
+                               $wgOut->parse( $this->getMessage( 'createaccount' ) ) .
+                               $this->getForm() .
+                               "</div>\n" );
+               }
+               return true;
+       }
+
+       /**
+        * Inject a captcha into the user login form after a failed
+        * password attempt as a speedbump for mass attacks.
+        * @fixme if multiple thingies insert a header, could break
+        * @param SimpleTemplate $template
+        * @return bool true to keep running callbacks
+        */
+       function injectUserLogin( &$template ) {
+               if( $this->isBadLoginTriggered() ) {
+                       global $wgOut;
+                       $template->set( 'header',
+                               "<div class='captcha'>" .
+                               $wgOut->parse( $this->getMessage( 'badlogin' ) ) .
+                               $this->getForm() .
+                               "</div>\n" );
+               }
+               return true;
+       }
+       
+       /**
+        * When a bad login attempt is made, increment an expiring counter
+        * in the memcache cloud. Later checks for this may trigger a
+        * captcha display to prevent too many hits from the same place.
+        * @param User $user
+        * @param string $password
+        * @param int $retval authentication return value
+        * @return bool true to keep running callbacks
+        */
+       function triggerUserLogin( $user, $password, $retval ) {
+               global $wgCaptchaTriggers, $wgCaptchaBadLoginExpiration, $wgMemc;
+               if( $retval == LoginForm::WRONG_PASS && $wgCaptchaTriggers['badlogin'] ) {
+                       $key = $this->badLoginKey();
+                       $count = $wgMemc->get( $key );
+                       if( !$count ) {
+                               $wgMemc->add( $key, 0, $wgCaptchaBadLoginExpiration );
+                       }
+                       $count = $wgMemc->incr( $key );
+               }
+               return true;
+       }
+       
+       /**
+        * Check if a bad login has already been registered for this
+        * IP address. If so, require a captcha.
+        * @return bool
+        * @access private
+        */
+       function isBadLoginTriggered() {
+               global $wgMemc;
+               return intval( $wgMemc->get( $this->badLoginKey() ) ) > 0;
+       }
+       
+       /**
+        * Internal cache key for badlogin checks.
+        * @return string
+        * @access private
+        */
+       function badLoginKey() {
+               return wfMemcKey( 'captcha', 'badlogin', 'ip', wfGetIP() );
+       }
+       
+       /**
+        * Check if the submitted form matches the captcha session data provided
+        * by the plugin when the form was generated.
+        *
+        * Override this!
+        *
+        * @param WebRequest $request
+        * @param array $info
+        * @return bool
+        */
+       function keyMatch( $request, $info ) {
+               return $request->getVal( 'wpCaptchaWord' ) == $info['answer'];
+       }
+
+       // ----------------------------------
+
+       /**
+        * @param EditPage $editPage
+        * @param string $action (edit/create/addurl...)
+        * @return bool true if action triggers captcha on editPage's namespace
+        */
+       function captchaTriggers( &$editPage, $action) {
+               global $wgCaptchaTriggers, $wgCaptchaTriggersOnNamespace;       
+               //Special config for this NS?
+               if (isset( $wgCaptchaTriggersOnNamespace[$editPage->mTitle->getNamespace()][$action] ) )
+                       return $wgCaptchaTriggersOnNamespace[$editPage->mTitle->getNamespace()][$action];
+
+               return ( !empty( $wgCaptchaTriggers[$action] ) ); //Default
+       }
+
+
        /**
         * @param EditPage $editPage
         * @param string $newtext
@@ -71,91 +386,301 @@ class SimpleCaptcha {
         * @return bool true if the captcha should run
         */
        function shouldCheck( &$editPage, $newtext, $section ) {
+               $this->trigger = '';
+
                global $wgUser;
                if( $wgUser->isAllowed( 'skipcaptcha' ) ) {
-                       wfDebug( "SimpleCaptcha: user group allows skipping captcha\n" );
+                       wfDebug( "ConfirmEdit: user group allows skipping captcha\n" );
                        return false;
                }
-       
+
                global $wgEmailAuthentication, $ceAllowConfirmedEmail;
                if( $wgEmailAuthentication && $ceAllowConfirmedEmail &&
                        $wgUser->isEmailConfirmed() ) {
-                       wfDebug( "SimpleCaptcha: user has confirmed mail, skipping captcha\n" );
+                       wfDebug( "ConfirmEdit: user has confirmed mail, skipping captcha\n" );
                        return false;
                }
-               
-               global $wgCaptchaTriggers;
-               if( !empty( $wgCaptchaTriggers['edit'] ) ) {
+
+               if( $this->captchaTriggers( $editPage, 'edit' ) ) {
                        // Check on all edits
-                       wfDebug( "SimpleCaptcha: checking all edits...\n" );
+                       global $wgUser, $wgTitle;
+                       $this->trigger = sprintf( "edit trigger by '%s' at [[%s]]",
+                               $wgUser->getName(),
+                               $wgTitle->getPrefixedText() );
+                       $this->action = 'edit';
+                       wfDebug( "ConfirmEdit: checking all edits...\n" );
+                       return true;
+               }
+
+               if( $this->captchaTriggers( $editPage, 'create' )  && !$editPage->mTitle->exists() ) {
+                       //Check if creating a page
+                       global $wgUser, $wgTitle;
+                       $this->trigger = sprintf( "Create trigger by '%s' at [[%s]]",
+                               $wgUser->getName(),
+                               $wgTitle->getPrefixedText() );
+                       $this->action = 'create';
+                       wfDebug( "ConfirmEdit: checking on page creation...\n" );
                        return true;
                }
-               
-               if( !empty( $wgCaptchaTriggers['addurl'] ) ) {
+
+               if( $this->captchaTriggers( $editPage, 'addurl' ) ) {
                        // Only check edits that add URLs
                        $oldtext = $this->loadText( $editPage, $section );
-                       
+
                        $oldLinks = $this->findLinks( $oldtext );
                        $newLinks = $this->findLinks( $newtext );
-                       
-                       $addedLinks = array_diff( $newLinks, $oldLinks );
+                       $unknownLinks = array_filter( $newLinks, array( &$this, 'filterLink' ) );
+
+                       $addedLinks = array_diff( $unknownLinks, $oldLinks );
                        $numLinks = count( $addedLinks );
-                       
+
                        if( $numLinks > 0 ) {
-                               wfDebug( "SimpleCaptcha: found $numLinks new links; triggered...\n" );
+                               global $wgUser, $wgTitle;
+                               $this->trigger = sprintf( "%dx url trigger by '%s' at [[%s]]: %s",
+                                       $numLinks,
+                                       $wgUser->getName(),
+                                       $wgTitle->getPrefixedText(),
+                                       implode( ", ", $addedLinks ) );
+                               $this->action = 'addurl';
                                return true;
                        }
                }
-               
+
+               global $wgCaptchaRegexes;
+               if( !empty( $wgCaptchaRegexes ) ) {
+                       // Custom regex checks
+                       $oldtext = $this->loadText( $editPage, $section );
+
+                       foreach( $wgCaptchaRegexes as $regex ) {
+                               $newMatches = array();
+                               if( preg_match_all( $regex, $newtext, $newMatches ) ) {
+                                       $oldMatches = array();
+                                       preg_match_all( $regex, $oldtext, $oldMatches );
+
+                                       $addedMatches = array_diff( $newMatches[0], $oldMatches[0] );
+
+                                       $numHits = count( $addedMatches );
+                                       if( $numHits > 0 ) {
+                                               global $wgUser, $wgTitle;
+                                               $this->trigger = sprintf( "%dx %s at [[%s]]: %s",
+                                                       $numHits,
+                                                       $regex,
+                                                       $wgUser->getName(),
+                                                       $wgTitle->getPrefixedText(),
+                                                       implode( ", ", $addedMatches ) );
+                                               $this->action = 'edit';
+                                               return true;
+                                       }
+                               }
+                       }
+               }
+
                return false;
        }
-       
+
+       /**
+        * Filter callback function for URL whitelisting
+        * @param string url to check
+        * @return bool true if unknown, false if whitelisted
+        * @access private
+        */
+       function filterLink( $url ) {
+               global $wgCaptchaWhitelist;
+               $source = wfMsgForContent( 'captcha-addurl-whitelist' );
+
+               $whitelist = wfEmptyMsg( 'captcha-addurl-whitelist', $source ) 
+                       ? false
+                       : $this->buildRegexes( explode( "\n", $source ) );
+
+               $cwl = $wgCaptchaWhitelist !== false ? preg_match( $wgCaptchaWhitelist, $url ) : false;
+               $wl  = $whitelist          !== false ? preg_match( $whitelist, $url )          : false;
+
+               return !( $cwl || $wl );
+       }
+
+       /**
+        * Build regex from whitelist
+        * @param string lines from [[MediaWiki:Captcha-addurl-whitelist]]
+        * @return string Regex or bool false if whitelist is empty
+        * @access private
+        */
+       function buildRegexes( $lines ) {
+               # Code duplicated from the SpamBlacklist extension (r19197)
+
+               # Strip comments and whitespace, then remove blanks
+               $lines = array_filter( array_map( 'trim', preg_replace( '/#.*$/', '', $lines ) ) );
+
+               # No lines, don't make a regex which will match everything
+               if ( count( $lines ) == 0 ) {
+                       wfDebug( "No lines\n" );
+                       return false;
+               } else {
+                       # Make regex
+                       # It's faster using the S modifier even though it will usually only be run once
+                       //$regex = 'http://+[a-z0-9_\-.]*(' . implode( '|', $lines ) . ')';
+                       //return '/' . str_replace( '/', '\/', preg_replace('|\\\*/|', '/', $regex) ) . '/Si';
+                       $regexes = '';
+                       $regexStart = '/http:\/\/+[a-z0-9_\-.]*(';
+                       $regexEnd = ')/Si';
+                       $regexMax = 4096;
+                       $build = false;
+                       foreach( $lines as $line ) {
+                               // FIXME: not very robust size check, but should work. :)
+                               if( $build === false ) {
+                                       $build = $line;
+                               } elseif( strlen( $build ) + strlen( $line ) > $regexMax ) {
+                                       $regexes .= $regexStart .
+                                               str_replace( '/', '\/', preg_replace('|\\\*/|', '/', $build) ) .
+                                               $regexEnd;
+                                       $build = $line;
+                               } else {
+                                       $build .= '|' . $line;
+                               }
+                       }
+                       if( $build !== false ) {
+                               $regexes .= $regexStart .
+                                       str_replace( '/', '\/', preg_replace('|\\\*/|', '/', $build) ) .
+                                       $regexEnd;
+                       }
+                       return $regexes;
+               }
+       }
+
+       /**
+        * The main callback run on edit attempts.
+        * @param EditPage $editPage
+        * @param string $newtext
+        * @param string $section
+        * @param bool true to continue saving, false to abort and show a captcha form
+        */
        function confirmEdit( &$editPage, $newtext, $section ) {
                if( $this->shouldCheck( $editPage, $newtext, $section ) ) {
-                       if( $this->keyMatch() ) {
-                               wfDebug( "ConfirmEdit given proper key from form, passing.\n" );
+                       if( $this->passCaptcha() ) {
                                return true;
                        } else {
-                               wfDebug( "ConfirmEdit missing form key, prompting.\n" );
-                               $editPage->showEditForm( array( &$this, 'formCallback' ) );
+                               $editPage->showEditForm( array( &$this, 'editCallback' ) );
                                return false;
                        }
                } else {
-                       wfDebug( "ConfirmEdit: no new links.\n" );
+                       wfDebug( "ConfirmEdit: no need to show captcha.\n" );
                        return true;
                }
        }
+
+       /**
+        * Hook for user creation form submissions.
+        * @param User $u
+        * @param string $message
+        * @return bool true to continue, false to abort user creation
+        */
+       function confirmUserCreate( $u, &$message ) {
+               global $wgCaptchaTriggers;
+               if( $wgCaptchaTriggers['createaccount'] ) {
+                       $this->trigger = "new account '" . $u->getName() . "'";
+                       if( !$this->passCaptcha() ) {
+                               $message = wfMsg( 'captcha-createaccount-fail' );
+                               return false;
+                       }
+               }
+               return true;
+       }
        
-       function keyMatch() {
-               if( !isset( $_SESSION['ceAnswerVar'] ) ) {
-                       wfDebug( "ConfirmEdit no session captcha key set, this is new visitor.\n" );
+       /**
+        * Hook for user login form submissions.
+        * @param User $u
+        * @param string $message
+        * @return bool true to continue, false to abort user creation
+        */
+       function confirmUserLogin( $u, $pass, &$retval ) {
+               if( $this->isBadLoginTriggered() ) {
+                       $this->trigger = "post-badlogin login '" . $u->getName() . "'";
+                       if( !$this->passCaptcha() ) {
+                               $message = wfMsg( 'captcha-badlogin-fail' );
+                               // Emulate a bad-password return to confuse the shit out of attackers
+                               $retval = LoginForm::WRONG_PASS;
+                               return false;
+                       }
+               }
+               return true;
+       }
+
+       /**
+        * Given a required captcha run, test form input for correct
+        * input on the open session.
+        * @return bool if passed, false if failed or new session
+        */
+       function passCaptcha() {
+               $info = $this->retrieveCaptcha();
+               if( $info ) {
+                       global $wgRequest;
+                       if( $this->keyMatch( $wgRequest, $info ) ) {
+                               $this->log( "passed" );
+                               $this->clearCaptcha( $info );
+                               return true;
+                       } else {
+                               $this->clearCaptcha( $info );
+                               $this->log( "bad form input" );
+                               return false;
+                       }
+               } else {
+                       $this->log( "new captcha session" );
                        return false;
                }
+       }
+
+       /**
+        * Log the status and any triggering info for debugging or statistics
+        * @param string $message
+        */
+       function log( $message ) {
+               wfDebugLog( 'captcha', 'ConfirmEdit: ' . $message . '; ' .  $this->trigger );
+       }
+
+       /**
+        * Generate a captcha session ID and save the info in PHP's session storage.
+        * (Requires the user to have cookies enabled to get through the captcha.)
+        *
+        * A random ID is used so legit users can make edits in multiple tabs or
+        * windows without being unnecessarily hobbled by a serial order requirement.
+        * Pass the returned id value into the edit form as wpCaptchaId.
+        *
+        * @param array $info data to store
+        * @return string captcha ID key
+        */
+       function storeCaptcha( $info ) {
+               if( !isset( $info['index'] ) ) {
+                       // Assign random index if we're not udpating
+                       $info['index'] = strval( mt_rand() );
+               }
+               $this->storage->store( $info['index'], $info );
+               return $info['index'];
+       }
+
+       /**
+        * Fetch this session's captcha info.
+        * @return mixed array of info, or false if missing
+        */
+       function retrieveCaptcha() {
                global $wgRequest;
-               return $wgRequest->getVal( $_SESSION['ceAnswerVar'] ) == $_SESSION['ceAnswer'];
+               $index = $wgRequest->getVal( 'wpCaptchaId' );
+               return $this->storage->retrieve( $index );
        }
-       
-       function formCallback( &$out ) {
-               $source = 'ceSource' . mt_rand();
-               $dest = 'ceConfirm' . mt_rand();
-               
-               $a = mt_rand(0, 100);
-               $b = mt_rand(0, 10);
-               $op = mt_rand(0, 1) ? '+' : '-';
-               
-               $test = "$a $op $b";
-               $answer = ($op == '+') ? ($a + $b) : ($a - $b);
-               $_SESSION['ceAnswer'] = $answer;
-               $_SESSION['ceAnswerVar'] = $dest;
-               
-               
-               $out->addWikiText( wfMsg( "captcha-short" ) );  
-               $out->addHTML( <<<END
-                       <p><span id="$source"><label for="$dest">$test</label></span> = <input name="$dest" id="$dest" /></p>
-END
-                       );
+
+       /**
+        * Clear out existing captcha info from the session, to ensure
+        * it can't be reused.
+        */
+       function clearCaptcha( $info ) {
+               $this->storage->clear( $info['index'] );
        }
-       
+
+       /**
+        * Retrieve the current version of the page or section being edited...
+        * @param EditPage $editPage
+        * @param string $section
+        * @return string
+        * @access private
+        */
        function loadText( $editPage, $section ) {
                $rev = Revision::newFromTitle( $editPage->mTitle );
                if( is_null( $rev ) ) {
@@ -169,30 +694,85 @@ END
                        }
                }
        }
-       
+
+       /**
+        * Extract a list of all recognized HTTP links in the text.
+        * @param string $text
+        * @return array of strings
+        */
        function findLinks( $text ) {
-               $regex = '/((?:' . HTTP_PROTOCOLS . ')' . EXT_LINK_URL_CLASS . '+)/';
-               
-               if( preg_match_all( $regex, $text, $matches, PREG_PATTERN_ORDER ) ) {
-                       return $matches[1];
-               } else {
-                       return array();
-               }
+               global $wgParser, $wgTitle, $wgUser;
+
+               $options = new ParserOptions();
+               $text = $wgParser->preSaveTransform( $text, $wgTitle, $wgUser, $options );
+               $out = $wgParser->parse( $text, $wgTitle, $options );
+
+               return array_keys( $out->getExternalLinks() );
        }
-       
+
+       /**
+        * Show a page explaining what this wacky thing is.
+        */
        function showHelp() {
                global $wgOut, $ceAllowConfirmedEmail;
-               $wgOut->setPageTitle( 'Captcha help' );
-               $wgOut->addWikiText( <<<END
-       So what's this wacky captcha thing about?
+               $wgOut->setPageTitle( wfMsg( 'captchahelp-title' ) );
+               $wgOut->addWikiText( wfMsg( 'captchahelp-text' ) );
+               if ( $this->storage->cookiesNeeded() ) {
+                       $wgOut->addWikiText( wfMsg( 'captchahelp-cookies-needed' ) );
+               }
+       }
+
+}
+
+class CaptchaSessionStore {
+       function store( $index, $info ) {
+               $_SESSION['captcha' . $info['index']] = $info;
+       }
        
-       It's your enemy. It's here to kill you. RUN WHILE YOU STILL CAN
-END
-                       );
+       function retrieve( $index ) {
+               if( isset( $_SESSION['captcha' . $index] ) ) {
+                       return $_SESSION['captcha' . $index];
+               } else {
+                       return false;
+               }
+       }
+       
+       function clear( $index ) {
+               unset( $_SESSION['captcha' . $index] );
+       }
+
+       function cookiesNeeded() {
+               return true;
+       }
+}
+
+class CaptchaCacheStore {
+       function store( $index, $info ) {
+               global $wgMemc, $wgCaptchaSessionExpiration;
+               $wgMemc->set( wfMemcKey( 'captcha', $index ), $info,
+                       $wgCaptchaSessionExpiration );
+       }
+
+       function retrieve( $index ) {
+               global $wgMemc;
+               $info = $wgMemc->get( wfMemcKey( 'captcha', $index ) );
+               if( $info ) {
+                       return $info;
+               } else {
+                       return false;
+               }
        }
        
+       function clear( $index ) {
+               global $wgMemc;
+               $wgMemc->delete( wfMemcKey( 'captcha', $index ) );
+       }
+
+       function cookiesNeeded() {
+               return false;
+       }
 }
 
 } # End invocation guard
 
-?>
+