mediawiki-extensions-Confir.../Captcha.php
2011-04-23 11:44:47 +00:00

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<?php
class SimpleCaptcha {
function __construct() {
global $wgCaptchaStorageClass;
$this->storage = new $wgCaptchaStorageClass;
}
function getCaptcha() {
$a = mt_rand( 0, 100 );
$b = mt_rand( 0, 10 );
/* Minus sign is used in the question. UTF-8,
since the api uses text/plain, not text/html */
$op = mt_rand( 0, 1 ) ? '+' : '';
$test = "$a $op $b";
$answer = ( $op == '+' ) ? ( $a + $b ) : ( $a - $b );
return array( 'question' => $test, 'answer' => $answer );
}
function addCaptchaAPI( &$resultArr ) {
$captcha = $this->getCaptcha();
$index = $this->storeCaptcha( $captcha );
$resultArr['captcha']['type'] = 'simple';
$resultArr['captcha']['mime'] = 'text/plain';
$resultArr['captcha']['id'] = $index;
$resultArr['captcha']['question'] = $captcha['question'];
}
/**
* 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() {
$captcha = $this->getCaptcha();
$index = $this->storeCaptcha( $captcha );
return "<p><label for=\"wpCaptchaWord\">{$captcha['question']}</label> = " .
Xml::element( 'input', array(
'name' => 'wpCaptchaWord',
'id' => 'wpCaptchaWord',
'tabindex' => 1 ) ) . // tab in before the edit textarea
"</p>\n" .
Xml::element( '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' ) : $text;
}
/**
* Inject whazawhoo
* @fixme if multiple thingies insert a header, could break
* @param HTMLForm
* @return bool true to keep running callbacks
*/
function injectEmailUser( &$form ) {
global $wgCaptchaTriggers, $wgOut, $wgUser;
if ( $wgCaptchaTriggers['sendemail'] ) {
if ( $wgUser->isAllowed( 'skipcaptcha' ) ) {
wfDebug( "ConfirmEdit: user group allows skipping captcha on email sending\n" );
return true;
}
$form->addFooterText(
"<div class='captcha'>" .
$wgOut->parse( $this->getMessage( 'sendemail' ) ) .
$this->getForm() .
"</div>\n" );
}
return true;
}
/**
* 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, $wgUser;
if ( $wgCaptchaTriggers['createaccount'] ) {
if ( $wgUser->isAllowed( 'skipcaptcha' ) ) {
wfDebug( "ConfirmEdit: user group allows skipping captcha on account creation\n" );
return true;
}
$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, $wgCaptchaBadLoginAttempts;
return intval( $wgMemc->get( $this->badLoginKey() ) ) >= $wgCaptchaBadLoginAttempts;
}
/**
* Check if the IP is allowed to skip captchas
*/
function isIPWhitelisted() {
global $wgCaptchaWhitelistIP;
if ( $wgCaptchaWhitelistIP ) {
$ip = wfGetIp();
foreach ( $wgCaptchaWhitelistIP as $range ) {
if ( IP::isInRange( $ip, $range ) ) {
return true;
}
}
}
return false;
}
/**
* 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 string $answer
* @param array $info
* @return bool
*/
function keyMatch( $answer, $info ) {
return $answer == $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
* @param string $section
* @return bool true if the captcha should run
*/
function shouldCheck( &$editPage, $newtext, $section, $merged = false ) {
$this->trigger = '';
$title = $editPage->mArticle->getTitle();
global $wgUser;
if ( $wgUser->isAllowed( 'skipcaptcha' ) ) {
wfDebug( "ConfirmEdit: user group allows skipping captcha\n" );
return false;
}
if ( $this->isIPWhitelisted() )
return false;
global $wgEmailAuthentication, $ceAllowConfirmedEmail;
if ( $wgEmailAuthentication && $ceAllowConfirmedEmail &&
$wgUser->isEmailConfirmed() ) {
wfDebug( "ConfirmEdit: user has confirmed mail, skipping captcha\n" );
return false;
}
if ( $this->captchaTriggers( $editPage, 'edit' ) ) {
// Check on all edits
global $wgUser;
$this->trigger = sprintf( "edit trigger by '%s' at [[%s]]",
$wgUser->getName(),
$title->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;
$this->trigger = sprintf( "Create trigger by '%s' at [[%s]]",
$wgUser->getName(),
$title->getPrefixedText() );
$this->action = 'create';
wfDebug( "ConfirmEdit: checking on page creation...\n" );
return true;
}
if ( $this->captchaTriggers( $editPage, 'addurl' ) ) {
// Only check edits that add URLs
if ( $merged ) {
// Get links from the database
$oldLinks = $this->getLinksFromTracker( $title );
// Share a parse operation with Article::doEdit()
$editInfo = $editPage->mArticle->prepareTextForEdit( $newtext );
$newLinks = array_keys( $editInfo->output->getExternalLinks() );
} else {
// Get link changes in the slowest way known to man
$oldtext = $this->loadText( $editPage, $section );
$oldLinks = $this->findLinks( $editPage, $oldtext );
$newLinks = $this->findLinks( $editPage, $newtext );
}
$unknownLinks = array_filter( $newLinks, array( &$this, 'filterLink' ) );
$addedLinks = array_diff( $unknownLinks, $oldLinks );
$numLinks = count( $addedLinks );
if ( $numLinks > 0 ) {
global $wgUser;
$this->trigger = sprintf( "%dx url trigger by '%s' at [[%s]]: %s",
$numLinks,
$wgUser->getName(),
$title->getPrefixedText(),
implode( ", ", $addedLinks ) );
$this->action = 'addurl';
return true;
}
}
global $wgCaptchaRegexes;
if ( $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;
$this->trigger = sprintf( "%dx %s at [[%s]]: %s",
$numHits,
$regex,
$wgUser->getName(),
$title->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 = '/^https?:\/\/+[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;
}
}
/**
* Load external links from the externallinks table
*/
function getLinksFromTracker( $title ) {
$dbr = wfGetDB( DB_SLAVE );
$id = $title->getArticleId(); // should be zero queries
$res = $dbr->select( 'externallinks', array( 'el_to' ),
array( 'el_from' => $id ), __METHOD__ );
$links = array();
foreach ( $res as $row ) {
$links[] = $row->el_to;
}
return $links;
}
/**
* Backend function for confirmEdit() and confirmEditAPI()
* @return bool false if the CAPTCHA is rejected, true otherwise
*/
private function doConfirmEdit( $editPage, $newtext, $section, $merged = false ) {
if ( $this->shouldCheck( $editPage, $newtext, $section, $merged ) ) {
if ( $this->passCaptcha() ) {
return true;
} else {
return false;
}
} else {
wfDebug( "ConfirmEdit: no need to show captcha.\n" );
return true;
}
}
/**
* The main callback run on edit attempts.
* @param EditPage $editPage
* @param string $newtext
* @param string $section
* @param bool $merged
* @return bool true to continue saving, false to abort and show a captcha form
*/
function confirmEdit( $editPage, $newtext, $section, $merged = false ) {
if ( defined( 'MW_API' ) ) {
# API mode
# The CAPTCHA was already checked and approved
return true;
}
if ( !$this->doConfirmEdit( $editPage, $newtext, $section, $merged ) ) {
$editPage->showEditForm( array( &$this, 'editCallback' ) );
return false;
}
return true;
}
/**
* A more efficient edit filter callback based on the text after section merging
* @param EditPage $editPage
* @param string $newtext
*/
function confirmEditMerged( $editPage, $newtext ) {
return $this->confirmEdit( $editPage, $newtext, false, true );
}
function confirmEditAPI( $editPage, $newtext, &$resultArr ) {
if ( !$this->doConfirmEdit( $editPage, $newtext, false, false ) ) {
$this->addCaptchaAPI( $resultArr );
return false;
}
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, $wgUser;
if ( $wgCaptchaTriggers['createaccount'] ) {
if ( $wgUser->isAllowed( 'skipcaptcha' ) ) {
wfDebug( "ConfirmEdit: user group allows skipping captcha on account creation\n" );
return true;
}
if ( $this->isIPWhitelisted() )
return true;
$this->trigger = "new account '" . $u->getName() . "'";
if ( !$this->passCaptcha() ) {
$message = wfMsg( 'captcha-createaccount-fail' );
return false;
}
}
return true;
}
/**
* 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() ) {
if ( $this->isIPWhitelisted() )
return true;
$this->trigger = "post-badlogin login '" . $u->getName() . "'";
if ( !$this->passCaptcha() ) {
// Emulate a bad-password return to confuse the shit out of attackers
$retval = LoginForm::WRONG_PASS;
return false;
}
}
return true;
}
/**
* Check the captcha on Special:EmailUser
* @param $from MailAddress
* @param $to MailAddress
* @param $subject String
* @param $text String
* @param $error String reference
* @return Bool true to continue saving, false to abort and show a captcha form
*/
function confirmEmailUser( $from, $to, $subject, $text, &$error ) {
global $wgCaptchaTriggers, $wgUser;
if ( $wgCaptchaTriggers['sendemail'] ) {
if ( $wgUser->isAllowed( 'skipcaptcha' ) ) {
wfDebug( "ConfirmEdit: user group allows skipping captcha on email sending\n" );
return true;
}
if ( $this->isIPWhitelisted() )
return true;
if ( defined( 'MW_API' ) ) {
# API mode
# Asking for captchas in the API is really silly
$error = wfMsg( 'captcha-disabledinapi' );
return false;
}
$this->trigger = "{$wgUser->getName()} sending email";
if ( !$this->passCaptcha() ) {
$error = wfMsg( 'captcha-sendemail-fail' );
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->getVal( 'wpCaptchaWord' ), $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;
$index = $wgRequest->getVal( 'wpCaptchaId' );
return $this->storage->retrieve( $index );
}
/**
* 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 ) ) {
return "";
} else {
$text = $rev->getText();
if ( $section != '' ) {
global $wgParser;
return $wgParser->getSection( $text, $section );
} else {
return $text;
}
}
}
/**
* Extract a list of all recognized HTTP links in the text.
* @param string $text
* @return array of strings
*/
function findLinks( &$editpage, $text ) {
global $wgParser, $wgUser;
$options = new ParserOptions();
$text = $wgParser->preSaveTransform( $text, $editpage->mTitle, $wgUser, $options );
$out = $wgParser->parse( $text, $editpage->mTitle, $options );
return array_keys( $out->getExternalLinks() );
}
/**
* Show a page explaining what this wacky thing is.
*/
function showHelp() {
global $wgOut;
$wgOut->setPageTitle( wfMsg( 'captchahelp-title' ) );
$wgOut->addWikiText( wfMsg( 'captchahelp-text' ) );
if ( $this->storage->cookiesNeeded() ) {
$wgOut->addWikiText( wfMsg( 'captchahelp-cookies-needed' ) );
}
}
}