diff --git a/xmlrpc.php b/xmlrpc.php
index cb997a9b33..d4f78d6e4f 100644
--- a/xmlrpc.php
+++ b/xmlrpc.php
@@ -238,6 +238,8 @@ class wp_xmlrpc_server extends IXR_Server {
 	 * @param string $user_login User's username.
 	 * @param string $user_pass User's password.
 	 * @return bool Whether authentication passed.
+	 * @deprecated use wp_xmlrpc_server::login
+	 * @see wp_xmlrpc_server::login
 	 */
 	function login_pass_ok($user_login, $user_pass) {
 		if ( !get_option( 'enable_xmlrpc' ) ) {
@@ -252,6 +254,32 @@ class wp_xmlrpc_server extends IXR_Server {
 		return true;
 	}
 
+	/**
+	 * Log user in.
+	 *
+	 * @since 2.8
+	 *
+	 * @param string $username User's username.
+	 * @param string $password User's password.
+	 * @return mixed WP_User object if authentication passed, false otherwise
+	 */
+	function login($username, $password) {
+		if ( !get_option( 'enable_xmlrpc' ) ) {
+			$this->error = new IXR_Error( 405, sprintf( __( 'XML-RPC services are disabled on this blog.  An admin user can enable them at %s'),  admin_url('options-writing.php') ) );
+			return false;
+		}
+
+		$user = wp_authenticate($username, $password);
+
+		if (is_wp_error($user)) {
+			$this->error = new IXR_Error(403, __('Bad login/pass combination.'));
+			return false;
+		}
+
+		set_current_user( $user->ID );
+		return $user;
+	}
+
 	/**
 	 * Sanitize string or array of strings for database.
 	 *
@@ -417,13 +445,12 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username = $args[0];
 		$password = $args[1];
 
-		if( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
 		do_action( 'xmlrpc_call', 'wp.getUsersBlogs' );
 
-		$user = set_current_user( 0, $username );
-
 		$blogs = (array) get_blogs_of_user( $user->ID );
 		$struct = array( );
 
@@ -466,11 +493,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username	= $args[2];
 		$password	= $args[3];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_page', $page_id ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit this page.' ) );
 
@@ -564,11 +590,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$num_pages	= (int) $args[3];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_pages' ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit pages.' ) );
 
@@ -616,15 +641,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$page		= $args[3];
 		$publish	= $args[4];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'wp.newPage');
 
-		// Set the user context and check if they are allowed
-		// to add new pages.
-		$user = set_current_user(0, $username);
+		// Make sure the user is allowed to add new pages.
 		if(!current_user_can("publish_pages")) {
 			return(new IXR_Error(401, __("Sorry, you can not add new pages.")));
 		}
@@ -652,8 +675,8 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$page_id	= (int) $args[3];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'wp.deletePage');
@@ -668,8 +691,7 @@ class wp_xmlrpc_server extends IXR_Server {
 			return(new IXR_Error(404, __("Sorry, no such page.")));
 		}
 
-		// Set the user context and make sure they can delete pages.
-		set_current_user(0, $username);
+		// Make sure the user can delete pages.
 		if(!current_user_can("delete_page", $page_id)) {
 			return(new IXR_Error(401, __("Sorry, you do not have the right to delete this page.")));
 		}
@@ -700,8 +722,8 @@ class wp_xmlrpc_server extends IXR_Server {
 		$content	= $args[4];
 		$publish	= $args[5];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'wp.editPage');
@@ -715,8 +737,7 @@ class wp_xmlrpc_server extends IXR_Server {
 			return(new IXR_Error(404, __("Sorry, no such page.")));
 		}
 
-		// Set the user context and make sure they are allowed to edit pages.
-		set_current_user(0, $username);
+		// Make sure the user is allowed to edit pages.
 		if(!current_user_can("edit_page", $page_id)) {
 			return(new IXR_Error(401, __("Sorry, you do not have the right to edit this page.")));
 		}
@@ -754,11 +775,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username				= $args[1];
 		$password				= $args[2];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_pages' ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit pages.' ) );
 
@@ -808,11 +828,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username	= $args[1];
 		$password	= $args[2];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
-		set_current_user(0, $username);
 		if(!current_user_can("edit_posts")) {
 			return(new IXR_Error(401, __("Sorry, you can not edit posts on this blog.")));
 		}
@@ -846,11 +865,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username		= $args[1];
 		$password		= $args[2];
 
-		if( !$this->login_pass_ok( $username, $password ) ) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_posts' ) ) {
 			return new IXR_Error( 401, __( 'Sorry, you must be able to edit posts on this blog in order to view tags.' ) );
 		}
@@ -891,15 +909,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password				= $args[2];
 		$category				= $args[3];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'wp.newCategory');
 
-		// Set the user context and make sure they are
-		// allowed to add a category.
-		set_current_user(0, $username);
+		// Make sure the user is allowed to add a category.
 		if(!current_user_can("manage_categories")) {
 			return(new IXR_Error(401, __("Sorry, you do not have the right to add a category.")));
 		}
@@ -951,13 +967,12 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password		= $args[2];
 		$category_id	= (int) $args[3];
 
-		if( !$this->login_pass_ok( $username, $password ) ) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'wp.deleteCategory');
 
-		set_current_user(0, $username);
 		if( !current_user_can("manage_categories") ) {
 			return new IXR_Error( 401, __( "Sorry, you do not have the right to delete a category." ) );
 		}
@@ -982,11 +997,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$category				= $args[3];
 		$max_results			= (int) $args[4];
 
-		if(!$this->login_pass_ok($username, $password)) {
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
 		}
 
-		set_current_user(0, $username);
 		if( !current_user_can( 'edit_posts' ) )
 			return new IXR_Error( 401, __( 'Sorry, you must be able to edit posts to this blog in order to view categories.' ) );
 
@@ -1020,10 +1034,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$comment_id	= (int) $args[3];
 
-		if ( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
-		set_current_user( 0, $username );
 		if ( !current_user_can( 'moderate_comments' ) )
 			return new IXR_Error( 403, __( 'You are not allowed to moderate comments on this blog.' ) );
 
@@ -1083,10 +1097,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$struct		= $args[3];
 
-		if ( !$this->login_pass_ok($username, $password) )
-			return($this->error);
+		if ( !$user = $this->login($username, $password) ) {
+			return $this->error;
+		}
 
-		set_current_user( 0, $username );
 		if ( !current_user_can( 'moderate_comments' ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit comments.' ) );
 
@@ -1143,10 +1157,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$comment_ID	= (int) $args[3];
 
-		if ( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
-		set_current_user( 0, $username );
 		if ( !current_user_can( 'moderate_comments' ) )
 			return new IXR_Error( 403, __( 'You are not allowed to moderate comments on this blog.' ) );
 
@@ -1175,10 +1189,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$comment_ID	= (int) $args[3];
 		$content_struct = $args[4];
 
-		if ( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
-		set_current_user( 0, $username );
 		if ( !current_user_can( 'moderate_comments' ) )
 			return new IXR_Error( 403, __( 'You are not allowed to moderate comments on this blog.' ) );
 
@@ -1249,7 +1263,9 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$allow_anon = apply_filters('xmlrpc_allow_anonymous_comments', false);
 
-		if ( !$this->login_pass_ok( $username, $password ) ) {
+		$user = $this->login($username, $password);
+
+		if ( !$user ) {
 			$logged_in = false;
 			if ( $allow_anon && get_option('comment_registration') )
 				return new IXR_Error( 403, __( 'You must be registered to comment' ) );
@@ -1257,7 +1273,6 @@ class wp_xmlrpc_server extends IXR_Server {
 				return $this->error;
 		} else {
 			$logged_in = true;
-			set_current_user( 0, $username );
 		}
 
 		if ( is_numeric($post) )
@@ -1274,7 +1289,6 @@ class wp_xmlrpc_server extends IXR_Server {
 		$comment['comment_post_ID'] = $post_id;
 
 		if ( $logged_in ) {
-			$user = wp_get_current_user();
 			$comment['comment_author'] = $wpdb->escape( $user->display_name );
 			$comment['comment_author_email'] = $wpdb->escape( $user->user_email );
 			$comment['comment_author_url'] = $wpdb->escape( $user->user_url );
@@ -1326,10 +1340,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username	= $args[1];
 		$password	= $args[2];
 
-		if ( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
-		set_current_user( 0, $username );
 		if ( !current_user_can( 'moderate_comments' ) )
 			return new IXR_Error( 403, __( 'You are not allowed access to details about this blog.' ) );
 
@@ -1354,11 +1368,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$post_id	= (int) $args[3];
 
-		if( !$this->login_pass_ok( $username, $password ) ) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_posts' ) ) {
 			return new IXR_Error( 403, __( 'You are not allowed access to details about comments.' ) );
 		}
@@ -1389,11 +1402,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username	= $args[1];
 		$password	= $args[2];
 
-		if( !$this->login_pass_ok( $username, $password ) ) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_posts' ) ) {
 			return new IXR_Error( 403, __( 'You are not allowed access to details about this blog.' ) );
 		}
@@ -1418,11 +1430,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username	= $args[1];
 		$password	= $args[2];
 
-		if( !$this->login_pass_ok( $username, $password ) ) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_posts' ) ) {
 			return new IXR_Error( 403, __( 'You are not allowed access to details about this blog.' ) );
 		}
@@ -1447,11 +1458,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$username	= $args[1];
 		$password	= $args[2];
 
-		if( !$this->login_pass_ok( $username, $password ) ) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $username );
 		if( !current_user_can( 'edit_pages' ) ) {
 			return new IXR_Error( 403, __( 'You are not allowed access to details about this blog.' ) );
 		}
@@ -1478,10 +1488,9 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$options	= (array) $args[3];
 
-		if( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
-
-		$user = set_current_user( 0, $username );
+		}
 
 		// If no specific options where asked for, return all of them
 		if (count( $options ) == 0 ) {
@@ -1533,10 +1542,10 @@ class wp_xmlrpc_server extends IXR_Server {
 		$password	= $args[2];
 		$options	= (array) $args[3];
 
-		if( !$this->login_pass_ok( $username, $password ) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
-		$user = set_current_user( 0, $username );
 		if( !current_user_can( 'manage_options' ) )
 			return new IXR_Error( 403, __( 'You are not allowed to update options.' ) );
 
@@ -1576,16 +1585,15 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$this->escape($args);
 
-		$user_login = $args[1];
-		$user_pass  = $args[2];
+		$username = $args[1];
+		$password  = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'blogger.getUsersBlogs');
 
-		set_current_user(0, $user_login);
 		$is_admin = current_user_can('manage_options');
 
 		$struct = array(
@@ -1613,27 +1621,24 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$this->escape($args);
 
-		$user_login = $args[1];
-		$user_pass  = $args[2];
+		$username = $args[1];
+		$password  = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
 		if( !current_user_can( 'edit_posts' ) )
 			return new IXR_Error( 401, __( 'Sorry, you do not have access to user data on this blog.' ) );
 
 		do_action('xmlrpc_call', 'blogger.getUserInfo');
 
-		$user_data = get_userdatabylogin($user_login);
-
 		$struct = array(
-			'nickname'  => $user_data->nickname,
-			'userid'    => $user_data->ID,
-			'url'       => $user_data->user_url,
-			'lastname'  => $user_data->last_name,
-			'firstname' => $user_data->first_name
+			'nickname'  => $user->nickname,
+			'userid'    => $user->ID,
+			'url'       => $user->user_url,
+			'lastname'  => $user->last_name,
+			'firstname' => $user->first_name
 		);
 
 		return $struct;
@@ -1652,14 +1657,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID    = (int) $args[1];
-		$user_login = $args[2];
-		$user_pass  = $args[3];
+		$username = $args[2];
+		$password  = $args[3];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
 		if( !current_user_can( 'edit_post', $post_ID ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit this post.' ) );
 
@@ -1696,11 +1700,11 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID    = (int) $args[1]; /* though we don't use it yet */
-		$user_login = $args[2];
-		$user_pass  = $args[3];
+		$username = $args[2];
+		$password  = $args[3];
 		$num_posts  = $args[4];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
@@ -1708,8 +1712,6 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$posts_list = wp_get_recent_posts($num_posts);
 
-		set_current_user( 0, $user_login );
-
 		if (!$posts_list) {
 			$this->error = new IXR_Error(500, __('Either there are no posts, or something went wrong.'));
 			return $this->error;
@@ -1756,17 +1758,16 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID    = (int) $args[1];
-		$user_login = $args[2];
-		$user_pass  = $args[3];
+		$username = $args[2];
+		$password  = $args[3];
 		$template   = $args[4]; /* could be 'main' or 'archiveIndex', but we don't use it */
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'blogger.getTemplate');
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('edit_themes') ) {
 			return new IXR_Error(401, __('Sorry, this user can not edit the template.'));
 		}
@@ -1798,18 +1799,17 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID    = (int) $args[1];
-		$user_login = $args[2];
-		$user_pass  = $args[3];
+		$username = $args[2];
+		$password  = $args[3];
 		$content    = $args[4];
 		$template   = $args[5]; /* could be 'main' or 'archiveIndex', but we don't use it */
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'blogger.setTemplate');
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('edit_themes') ) {
 			return new IXR_Error(401, __('Sorry, this user can not edit the template.'));
 		}
@@ -1841,19 +1841,18 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID    = (int) $args[1]; /* though we don't use it yet */
-		$user_login = $args[2];
-		$user_pass  = $args[3];
+		$username = $args[2];
+		$password  = $args[3];
 		$content    = $args[4];
 		$publish    = $args[5];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'blogger.newPost');
 
 		$cap = ($publish) ? 'publish_posts' : 'edit_posts';
-		$user = set_current_user(0, $user_login);
 		if ( !current_user_can($cap) )
 			return new IXR_Error(401, __('Sorry, you are not allowed to post on this blog.'));
 
@@ -1897,12 +1896,12 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[1];
-		$user_login  = $args[2];
-		$user_pass   = $args[3];
+		$username  = $args[2];
+		$password   = $args[3];
 		$content     = $args[4];
 		$publish     = $args[5];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
@@ -1916,7 +1915,6 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		$this->escape($actual_post);
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('edit_post', $post_ID) )
 			return new IXR_Error(401, __('Sorry, you do not have the right to edit this post.'));
 
@@ -1953,11 +1951,11 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[1];
-		$user_login  = $args[2];
-		$user_pass   = $args[3];
+		$username  = $args[2];
+		$password   = $args[3];
 		$publish     = $args[4];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
@@ -1969,7 +1967,6 @@ class wp_xmlrpc_server extends IXR_Server {
 			return new IXR_Error(404, __('Sorry, no such post.'));
 		}
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('edit_post', $post_ID) )
 			return new IXR_Error(401, __('Sorry, you do not have the right to delete this post.'));
 
@@ -1998,15 +1995,14 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID     = (int) $args[0]; // we will support this in the near future
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 		$content_struct = $args[3];
 		$publish     = $args[4];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
-		$user = set_current_user(0, $user_login);
 
 		do_action('xmlrpc_call', 'metaWeblog.newPost');
 
@@ -2296,15 +2292,14 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 		$content_struct = $args[3];
 		$publish     = $args[4];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
-		$user = set_current_user(0, $user_login);
 
 		do_action('xmlrpc_call', 'metaWeblog.editPost');
 
@@ -2561,14 +2556,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
 		if( !current_user_can( 'edit_post', $post_ID ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit this post.' ) );
 
@@ -2673,11 +2667,11 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 		$num_posts   = (int) $args[3];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
@@ -2689,8 +2683,6 @@ class wp_xmlrpc_server extends IXR_Server {
 			return array( );
 		}
 
-		set_current_user( 0, $user_login );
-
 		foreach ($posts_list as $entry) {
 			if( !current_user_can( 'edit_post', $entry['ID'] ) )
 				continue;
@@ -2777,14 +2769,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
 		if( !current_user_can( 'edit_posts' ) )
 			return new IXR_Error( 401, __( 'Sorry, you must be able to edit posts on this blog in order to view categories.' ) );
 
@@ -2825,8 +2816,8 @@ class wp_xmlrpc_server extends IXR_Server {
 		global $wpdb;
 
 		$blog_ID     = (int) $args[0];
-		$user_login  = $wpdb->escape($args[1]);
-		$user_pass   = $wpdb->escape($args[2]);
+		$username  = $wpdb->escape($args[1]);
+		$password   = $wpdb->escape($args[2]);
 		$data        = $args[3];
 
 		$name = sanitize_file_name( $data['name'] );
@@ -2835,12 +2826,12 @@ class wp_xmlrpc_server extends IXR_Server {
 
 		logIO('O', '(MW) Received '.strlen($bits).' bytes');
 
-		if ( !$this->login_pass_ok($user_login, $user_pass) )
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
+		}
 
 		do_action('xmlrpc_call', 'metaWeblog.newMediaObject');
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('upload_files') ) {
 			logIO('O', '(MW) User does not have upload_files capability');
 			$this->error = new IXR_Error(401, __('You are not allowed to upload files to this site.'));
@@ -2910,11 +2901,11 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 		$num_posts   = (int) $args[3];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
@@ -2927,8 +2918,6 @@ class wp_xmlrpc_server extends IXR_Server {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
-
 		foreach ($posts_list as $entry) {
 			if( !current_user_can( 'edit_post', $entry['ID'] ) )
 				continue;
@@ -2967,14 +2956,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$blog_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
 		if( !current_user_can( 'edit_posts' ) )
 			return new IXR_Error( 401, __( 'Sorry, you must be able to edit posts on this blog in order to view categories.' ) );
 
@@ -3007,14 +2995,13 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
-		set_current_user( 0, $user_login );
 		if( !current_user_can( 'edit_post', $post_ID ) )
 			return new IXR_Error( 401, __( 'Sorry, you can not edit this post.' ) );
 
@@ -3049,17 +3036,16 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 		$categories  = $args[3];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'mt.setPostCategories');
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('edit_post', $post_ID) )
 			return new IXR_Error(401, __('Sorry, you can not edit this post.'));
 
@@ -3161,16 +3147,15 @@ class wp_xmlrpc_server extends IXR_Server {
 		$this->escape($args);
 
 		$post_ID     = (int) $args[0];
-		$user_login  = $args[1];
-		$user_pass   = $args[2];
+		$username  = $args[1];
+		$password   = $args[2];
 
-		if (!$this->login_pass_ok($user_login, $user_pass)) {
+		if ( !$user = $this->login($username, $password) ) {
 			return $this->error;
 		}
 
 		do_action('xmlrpc_call', 'mt.publishPost');
 
-		set_current_user(0, $user_login);
 		if ( !current_user_can('edit_post', $post_ID) )
 			return new IXR_Error(401, __('Sorry, you can not edit this post.'));