bp-core-catchuri.php

<?php

/**
 * BuddyPress URI catcher
 *
 * Functions for parsing the URI and determining which BuddyPress template file
 * to use on-screen.
 *
 * @package BuddyPress
 * @subpackage Core
 */

// Exit if accessed directly
if ( !defined( 'ABSPATH' ) ) exit;

/**
 * Analyzes the URI structure and breaks it down into parts for use in code.
 * BuddyPress can use complete custom friendly URI's without the user having to
 * add new re-write rules. Custom components are able to use their own custom
 * URI structures with very little work.
 *
 * @package BuddyPress Core
 * @since BuddyPress (1.0)
 *
 * The URI's are broken down as follows:
 *   - http:// domain.com / members / andy / [current_component] / [current_action] / [action_variables] / [action_variables] / ...
 *   - OUTSIDE ROOT: http:// domain.com / sites / buddypress / members / andy / [current_component] / [current_action] / [action_variables] / [action_variables] / ...
 *
 *  Example:
 *    - http://domain.com/members/andy/profile/edit/group/5/
 *    - $bp->current_component: string 'xprofile'
 *    - $bp->current_action: string 'edit'
 *    - $bp->action_variables: array ['group', 5]
 *
 */
function bp_core_set_uri_globals() {
    global $bp, $current_blog, $wp_rewrite;

    // Don't catch URIs on non-root blogs unless multiblog mode is on
    if ( !bp_is_root_blog() && !bp_is_multiblog_mode() )
        return false;

    // Define local variables
    $root_profile = $match   = false;
    $key_slugs    = $matches = $uri_chunks = array();

    // Fetch all the WP page names for each component
    if ( empty( $bp->pages ) )
        $bp->pages = bp_core_get_directory_pages();

    // Ajax or not?
    if ( defined( 'DOING_AJAX' ) && DOING_AJAX || strpos( $_SERVER['REQUEST_URI'], 'wp-load.php' ) )
        $path = bp_core_referrer();
    else
        $path = esc_url( $_SERVER['REQUEST_URI'] );

    // Filter the path
    $path = apply_filters( 'bp_uri', $path );

    // Take GET variables off the URL to avoid problems
    $path = strtok( $path, '?' );

    // Fetch current URI and explode each part separated by '/' into an array
    $bp_uri = explode( '/', $path );

    // Loop and remove empties
    foreach ( (array) $bp_uri as $key => $uri_chunk ) {
        if ( empty( $bp_uri[$key] ) ) {
            unset( $bp_uri[$key] );
        }
    }

    // If running off blog other than root, any subdirectory names must be
    // removed from $bp_uri. This includes two cases:
    //
    //    1. when WP is installed in a subdirectory,
    //    2. when BP is running on secondary blog of a subdirectory
    //       multisite installation. Phew!
    if ( is_multisite() && !is_subdomain_install() && ( bp_is_multiblog_mode() || 1 != bp_get_root_blog_id() ) ) {

        // Blow chunks
        $chunks = explode( '/', $current_blog->path );

        // If chunks exist...
        if ( !empty( $chunks ) ) {

            // ...loop through them...
            foreach( $chunks as $key => $chunk ) {
                $bkey = array_search( $chunk, $bp_uri );

                // ...and unset offending keys
                if ( false !== $bkey ) {
                    unset( $bp_uri[$bkey] );
                }

                $bp_uri = array_values( $bp_uri );
            }
        }
    }

    // Get site path items
    $paths = explode( '/', bp_core_get_site_path() );

    // Take empties off the end of path
    if ( empty( $paths[count( $paths ) - 1] ) )
        array_pop( $paths );

    // Take empties off the start of path
    if ( empty( $paths[0] ) )
        array_shift( $paths );

    // Reset indexes
    $bp_uri = array_values( $bp_uri );
    $paths  = array_values( $paths );

    // Unset URI indices if they intersect with the paths
    foreach ( (array) $bp_uri as $key => $uri_chunk ) {
        if ( isset( $paths[$key] ) && $uri_chunk == $paths[$key] ) {
            unset( $bp_uri[$key] );
        }
    }

    // Reset the keys by merging with an empty array
    $bp_uri = array_merge( array(), $bp_uri );

    // If a component is set to the front page, force its name into $bp_uri
    // so that $current_component is populated (unless a specific WP post is being requested
    // via a URL parameter, usually signifying Preview mode)
    if ( 'page' == get_option( 'show_on_front' ) && get_option( 'page_on_front' ) && empty( $bp_uri ) && empty( $_GET['p'] ) && empty( $_GET['page_id'] ) ) {
        $post = get_post( get_option( 'page_on_front' ) );
        if ( !empty( $post ) ) {
            $bp_uri[0] = $post->post_name;
        }
    }

    // Keep the unfiltered URI safe
    $bp->unfiltered_uri = $bp_uri;

    // Get slugs of pages into array
    foreach ( (array) $bp->pages as $page_key => $bp_page )
        $key_slugs[$page_key] = trailingslashit( '/' . $bp_page->slug );

    // Bail if keyslugs are empty, as BP is not setup correct
    if ( empty( $key_slugs ) )
        return;

    // Loop through page slugs and look for exact match to path
    foreach ( $key_slugs as $key => $slug ) {
        if ( $slug == $path ) {
            $match      = $bp->pages->{$key};
            $match->key = $key;
            $matches[]  = 1;
            break;
        }
    }

    // No exact match, so look for partials
    if ( empty( $match ) ) {

        // Loop through each page in the $bp->pages global
        foreach ( (array) $bp->pages as $page_key => $bp_page ) {

            // Look for a match (check members first)
            if ( in_array( $bp_page->name, (array) $bp_uri ) ) {

                // Match found, now match the slug to make sure.
                $uri_chunks = explode( '/', $bp_page->slug );

                // Loop through uri_chunks
                foreach ( (array) $uri_chunks as $key => $uri_chunk ) {

                    // Make sure chunk is in the correct position
                    if ( !empty( $bp_uri[$key] ) && ( $bp_uri[$key] == $uri_chunk ) ) {
                        $matches[] = 1;

                    // No match
                    } else {
                        $matches[] = 0;
                    }
                }

                // Have a match
                if ( !in_array( 0, (array) $matches ) ) {
                    $match      = $bp_page;
                    $match->key = $page_key;
                    break;
                };

                // Unset matches
                unset( $matches );
            }

            // Unset uri chunks
            unset( $uri_chunks );
        }
    }

    // URLs with BP_ENABLE_ROOT_PROFILES enabled won't be caught above
    if ( empty( $matches ) && bp_core_enable_root_profiles() ) {

        // Switch field based on compat
        $field = bp_is_username_compatibility_mode() ? 'login' : 'slug';

        // Make sure there's a user corresponding to $bp_uri[0]
        if ( !empty( $bp->pages->members ) && !empty( $bp_uri[0] ) && $root_profile = get_user_by( $field, $bp_uri[0] ) ) {

            // Force BP to recognize that this is a members page
            $matches[]  = 1;
            $match      = $bp->pages->members;
            $match->key = 'members';

            // Without the 'members' URL chunk, WordPress won't know which page to load
            // This filter intercepts the WP query and tells it to load the members page
            add_filter( 'request', create_function( '$query_args', '$query_args["pagename"] = "' . $match->name . '"; return $query_args;' ) );
        }
    }

    // Search doesn't have an associated page, so we check for it separately
    if ( !empty( $bp_uri[0] ) && ( bp_get_search_slug() == $bp_uri[0] ) ) {
        $matches[]   = 1;
        $match       = new stdClass;
        $match->key  = 'search';
        $match->slug = bp_get_search_slug();
    }

    // This is not a BuddyPress page, so just return.
    if ( empty( $matches ) )
        return false;

    $wp_rewrite->use_verbose_page_rules = false;

    // Find the offset. With $root_profile set, we fudge the offset down so later parsing works
    $slug       = !empty ( $match ) ? explode( '/', $match->slug ) : '';
    $uri_offset = empty( $root_profile ) ? 0 : -1;

    // Rejig the offset
    if ( !empty( $slug ) && ( 1 < count( $slug ) ) ) {
        array_pop( $slug );
        $uri_offset = count( $slug );
    }

    // Global the unfiltered offset to use in bp_core_load_template().
    // To avoid PHP warnings in bp_core_load_template(), it must always be >= 0
    $bp->unfiltered_uri_offset = $uri_offset >= 0 ? $uri_offset : 0;

    // We have an exact match
    if ( isset( $match->key ) ) {

        // Set current component to matched key
        $bp->current_component = $match->key;

        // If members component, do more work to find the actual component
        if ( 'members' == $match->key ) {

            // Viewing a specific user
            if ( !empty( $bp_uri[$uri_offset + 1] ) ) {

                // Switch the displayed_user based on compatbility mode
                if ( bp_is_username_compatibility_mode() ) {
                    $bp->displayed_user->id = (int) bp_core_get_userid( urldecode( $bp_uri[$uri_offset + 1] ) );
                } else {
                    $bp->displayed_user->id = (int) bp_core_get_userid_from_nicename( urldecode( $bp_uri[$uri_offset + 1] ) );
                }

                if ( !bp_displayed_user_id() ) {

                    // Prevent components from loading their templates
                    $bp->current_component = '';

                    bp_do_404();
                    return;
                }

                // If the displayed user is marked as a spammer, 404 (unless logged-
                // in user is a super admin)
                if ( bp_displayed_user_id() && bp_is_user_spammer( bp_displayed_user_id() ) ) {
                    if ( bp_current_user_can( 'bp_moderate' ) ) {
                        bp_core_add_message( __( 'This user has been marked as a spammer. Only site admins can view this profile.', 'buddypress' ), 'warning' );
                    } else {
                        bp_do_404();
                        return;
                    }
                }

                // Bump the offset
                if ( isset( $bp_uri[$uri_offset + 2] ) ) {
                    $bp_uri                = array_merge( array(), array_slice( $bp_uri, $uri_offset + 2 ) );
                    $bp->current_component = $bp_uri[0];

                // No component, so default will be picked later
                } else {
                    $bp_uri                = array_merge( array(), array_slice( $bp_uri, $uri_offset + 2 ) );
                    $bp->current_component = '';
                }

                // Reset the offset
                $uri_offset = 0;
            }
        }
    }

    // Set the current action
    $bp->current_action = isset( $bp_uri[$uri_offset + 1] ) ? $bp_uri[$uri_offset + 1] : '';

    // Slice the rest of the $bp_uri array and reset offset
    $bp_uri      = array_slice( $bp_uri, $uri_offset + 2 );
    $uri_offset  = 0;

    // Set the entire URI as the action variables, we will unset the current_component and action in a second
    $bp->action_variables = $bp_uri;

    // Reset the keys by merging with an empty array
    $bp->action_variables = array_merge( array(), $bp->action_variables );
}

/**
 * Are root profiles enabled and allowed
 *
 * @since BuddyPress (1.6)
 * @return bool True if yes, false if no
 */
function bp_core_enable_root_profiles() {

    $retval = false;

    if ( defined( 'BP_ENABLE_ROOT_PROFILES' ) && ( true == BP_ENABLE_ROOT_PROFILES ) )
        $retval = true;

    return apply_filters( 'bp_core_enable_root_profiles', $retval );
}

/**
 * bp_core_load_template()
 *
 * Load a specific template file with fallback support.
 *
 * Example:
 *   bp_core_load_template( 'members/index' );
 * Loads:
 *   wp-content/themes/[activated_theme]/members/index.php
 *
 * @package BuddyPress Core
 * @param $username str Username to check.
 * @return false|int The user ID of the matched user, or false.
 */
function bp_core_load_template( $templates ) {
    global $post, $bp, $wp_query, $wpdb;

    // Determine if the root object WP page exists for this request
    // note: get_page_by_path() breaks non-root pages
    if ( !empty( $bp->unfiltered_uri_offset ) ) {
        if ( !$page_exists = $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM {$wpdb->posts} WHERE post_name = %s", $bp->unfiltered_uri[$bp->unfiltered_uri_offset] ) ) ) {
            return false;
        }
    }

    // Set the root object as the current wp_query-ied item
    $object_id = 0;
    foreach ( (array) $bp->pages as $page ) {
        if ( $page->name == $bp->unfiltered_uri[$bp->unfiltered_uri_offset] ) {
            $object_id = $page->id;
        }
    }

    // Make the queried/post object an actual valid page
    if ( !empty( $object_id ) ) {
        $wp_query->queried_object    = &get_post( $object_id );
        $wp_query->queried_object_id = $object_id;
        $post                        = $wp_query->queried_object;
    }

    // Define local variables
    $located_template   = false;
    $filtered_templates = array();

    // Fetch each template and add the php suffix
    foreach ( (array) $templates as $template )
        $filtered_templates[] = $template . '.php';

    // Filter the template locations so that plugins can alter where they are located
    $located_template = apply_filters( 'bp_located_template', locate_template( (array) $filtered_templates, false ), $filtered_templates );
    if ( !empty( $located_template ) ) {

        // Template was located, lets set this as a valid page and not a 404.
        status_header( 200 );
        $wp_query->is_page = $wp_query->is_singular = true;
        $wp_query->is_404  = false;

        do_action( 'bp_core_pre_load_template', $located_template );

        load_template( apply_filters( 'bp_load_template', $located_template ) );

        do_action( 'bp_core_post_load_template', $located_template );
    }

    // Kill any other output after this.
    die;
}

/**
 * bp_core_catch_profile_uri()
 *
 * If the extended profiles component is not installed we still need
 * to catch the /profile URI's and display whatever we have installed.
 *
 */
function bp_core_catch_profile_uri() {
    if ( !bp_is_active( 'xprofile' ) ) {
        bp_core_load_template( apply_filters( 'bp_core_template_display_profile', 'members/single/home' ) );
    }
}

/**
 * Catches invalid access to BuddyPress pages and redirects them accordingly.
 *
 * @package BuddyPress Core
 * @since BuddyPress (1.5)
 */
function bp_core_catch_no_access() {
    global $bp, $wp_query;

    // If coming from bp_core_redirect() and $bp_no_status_set is true,
    // we are redirecting to an accessible page so skip this check.
    if ( !empty( $bp->no_status_set ) )
        return false;

    if ( !isset( $wp_query->queried_object ) && !bp_is_blog_page() ) {
        bp_do_404();
    }
}
add_action( 'bp_template_redirect', 'bp_core_catch_no_access', 1 );

/**
 * Redirects a user to login for BP pages that require access control and adds an error message (if
 * one is provided).
 * If authenticated, redirects user back to requested content by default.
 *
 * @package BuddyPress Core
 * @since BuddyPress (1.5)
 */
function bp_core_no_access( $args = '' ) {

    // Build the redirect URL
    $redirect_url  = is_ssl() ? 'https://' : 'http://';
    $redirect_url .= $_SERVER['HTTP_HOST'];
    $redirect_url .= $_SERVER['REQUEST_URI'];

    $defaults = array(
        'mode'     => '1',                  // 1 = $root, 2 = wp-login.php
        'redirect' => $redirect_url,        // the URL you get redirected to when a user successfully logs in
        'root'     => bp_get_root_domain(), // the landing page you get redirected to when a user doesn't have access
        'message'  => __( 'You must log in to access the page you requested.', 'buddypress' )
    );

    $r = wp_parse_args( $args, $defaults );
    $r = apply_filters( 'bp_core_no_access', $r );
    extract( $r, EXTR_SKIP );

    /**
     * @ignore Ignore these filters and use 'bp_core_no_access' above
     */
    $mode       = apply_filters( 'bp_no_access_mode',     $mode,     $root,     $redirect, $message );
    $redirect   = apply_filters( 'bp_no_access_redirect', $redirect, $root,     $message,  $mode    );
    $root       = apply_filters( 'bp_no_access_root',     $root,     $redirect, $message,  $mode    );
    $message    = apply_filters( 'bp_no_access_message',  $message,  $root,     $redirect, $mode    );
    $root       = trailingslashit( $root );

    switch ( $mode ) {

        // Option to redirect to wp-login.php
        // Error message is displayed with bp_core_no_access_wp_login_error()
        case 2 :
            if ( !empty( $redirect ) ) {
                bp_core_redirect( add_query_arg( array( 'action' => 'bpnoaccess' ), wp_login_url( $redirect ) ) );
            } else {
                bp_core_redirect( $root );
            }

            break;

        // Redirect to root with "redirect_to" parameter
        // Error message is displayed with bp_core_add_message()
        case 1 :
        default :

            $url = $root;
            if ( !empty( $redirect ) )
                $url = add_query_arg( 'redirect_to', urlencode( $redirect ), $root );

            if ( !empty( $message ) ) {
                bp_core_add_message( $message, 'error' );
            }

            bp_core_redirect( $url );

            break;
    }
}

/**
 * Adds an error message to wp-login.php.
 * Hooks into the "bpnoaccess" action defined in bp_core_no_access().
 *
 * @package BuddyPress Core
 * @global $error
 * @since BuddyPress (1.5)
 */
function bp_core_no_access_wp_login_error() {
    global $error;

    $error = apply_filters( 'bp_wp_login_error', __( 'You must log in to access the page you requested.', 'buddypress' ), $_REQUEST['redirect_to'] );

    // shake shake shake!
    add_action( 'login_head', 'wp_shake_js', 12 );
}
add_action( 'login_form_bpnoaccess', 'bp_core_no_access_wp_login_error' );

/**
 * Canonicalizes BuddyPress URLs
 *
 * This function ensures that requests for BuddyPress content are always redirected to their
 * canonical versions. Canonical versions are always trailingslashed, and are typically the most
 * general possible versions of the URL - eg, example.com/groups/mygroup/ instead of
 * example.com/groups/mygroup/home/
 *
 * @since 1.6
 * @see BP_Members_Component::setup_globals() where $bp->canonical_stack['base_url'] and
 *   ['component'] may be set
 * @see bp_core_new_nav_item() where $bp->canonical_stack['action'] may be set
 * @uses bp_get_canonical_url()
 * @uses bp_get_requested_url()
 */
function bp_redirect_canonical() {
    global $bp;

    if ( !bp_is_blog_page() && apply_filters( 'bp_do_redirect_canonical', true ) ) {
        // If this is a POST request, don't do a canonical redirect.
        // This is for backward compatibility with plugins that submit form requests to
        // non-canonical URLs. Plugin authors should do their best to use canonical URLs in
        // their form actions.
        if ( !empty( $_POST ) ) {
            return;
        }

        // build the URL in the address bar
        $requested_url  = bp_get_requested_url();

        // Stash query args
        $url_stack      = explode( '?', $requested_url );
        $req_url_clean  = $url_stack[0];
        $query_args     = isset( $url_stack[1] ) ? $url_stack[1] : '';

        $canonical_url  = bp_get_canonical_url();

        // Only redirect if we've assembled a URL different from the request
        if ( $canonical_url !== $req_url_clean ) {

            // Template messages have been deleted from the cookie by this point, so
            // they must be readded before redirecting
            if ( isset( $bp->template_message ) ) {
                $message      = stripslashes( $bp->template_message );
                $message_type = isset( $bp->template_message_type ) ? $bp->template_message_type : 'success';

                bp_core_add_message( $message, $message_type );
            }

            if ( !empty( $query_args ) ) {
                $canonical_url .= '?' . $query_args;
            }

            bp_core_redirect( $canonical_url, 301 );
        }
    }
}

/**
 * Output rel=canonical header tag for BuddyPress content
 *
 * @since 1.6
 */
function bp_rel_canonical() {
    $canonical_url = bp_get_canonical_url();

    // Output rel=canonical tag
    echo "<link rel='canonical' href='" . esc_attr( $canonical_url ) . "' />\n";
}

/**
 * Returns the canonical URL of the current page
 *
 * @since BuddyPress (1.6)
 * @uses apply_filters() Filter bp_get_canonical_url to modify return value
 * @param array $args
 * @return string
 */
function bp_get_canonical_url( $args = array() ) {
    global $bp;

    // For non-BP content, return the requested url, and let WP do the work
    if ( bp_is_blog_page() ) {
        return bp_get_requested_url();
    }

    $defaults = array(
        'include_query_args' => false // Include URL arguments, eg ?foo=bar&foo2=bar2
    );
    $r = wp_parse_args( $args, $defaults );
    extract( $r );

    if ( empty( $bp->canonical_stack['canonical_url'] ) ) {
        // Build the URL in the address bar
        $requested_url  = bp_get_requested_url();

        // Stash query args
        $url_stack      = explode( '?', $requested_url );

        // Build the canonical URL out of the redirect stack
        if ( isset( $bp->canonical_stack['base_url'] ) )
            $url_stack[0] = $bp->canonical_stack['base_url'];

        if ( isset( $bp->canonical_stack['component'] ) )
            $url_stack[0] = trailingslashit( $url_stack[0] . $bp->canonical_stack['component'] );

        if ( isset( $bp->canonical_stack['action'] ) )
            $url_stack[0] = trailingslashit( $url_stack[0] . $bp->canonical_stack['action'] );

        if ( !empty( $bp->canonical_stack['action_variables'] ) ) {
            foreach( (array) $bp->canonical_stack['action_variables'] as $av ) {
                $url_stack[0] = trailingslashit( $url_stack[0] . $av );
            }
        }

        // Add trailing slash
        $url_stack[0] = trailingslashit( $url_stack[0] );

        // Stash in the $bp global
        $bp->canonical_stack['canonical_url'] = implode( '?', $url_stack );
    }

    $canonical_url = $bp->canonical_stack['canonical_url'];

    if ( !$include_query_args ) {
        $canonical_url = array_pop( array_reverse( explode( '?', $canonical_url ) ) );
    }

    return apply_filters( 'bp_get_canonical_url', $canonical_url, $args );
}

/**
 * Returns the URL as requested on the current page load by the user agent
 *
 * @since BuddyPress (1.6)
 * @return string
 */
function bp_get_requested_url() {
    global $bp;

    if ( empty( $bp->canonical_stack['requested_url'] ) ) {
        $bp->canonical_stack['requested_url']  = is_ssl() ? 'https://' : 'http://';
        $bp->canonical_stack['requested_url'] .= $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    }

    return $bp->canonical_stack['requested_url'];
}

/**
 * Remove WordPress's really awesome canonical redirect if we are trying to load
 * BuddyPress specific content. Avoids issues with WordPress thinking that a
 * BuddyPress URL might actually be a blog post or page.
 *
 * This function should be considered temporary, and may be removed without
 * notice in future versions of BuddyPress.
 *
 * @since BuddyPress (1.6)
 * @uses bp_is_blog_page()
 */
function _bp_maybe_remove_redirect_canonical() {
    if ( ! bp_is_blog_page() )
        remove_action( 'template_redirect', 'redirect_canonical' );
}
add_action( 'bp_init', '_bp_maybe_remove_redirect_canonical' );

/**
 * Rehook maybe_redirect_404() to run later than the default
 *
 * WordPress's maybe_redirect_404() allows admins on a multisite installation
 * to define 'NOBLOGREDIRECT', a URL to which 404 requests will be redirected.
 * maybe_redirect_404() is hooked to template_redirect at priority 10, which
 * creates a race condition with bp_template_redirect(), our piggyback hook.
 * Due to a legacy bug in BuddyPress, internal BP content (such as members and
 * groups) is marked 404 in $wp_query until bp_core_load_template(), when BP
 * manually overrides the automatic 404. However, the race condition with
 * maybe_redirect_404() means that this manual un-404-ing doesn't happen in
 * time, with the results that maybe_redirect_404() thinks that the page is
 * a legitimate 404, and redirects incorrectly to NOBLOGREDIRECT.
 *
 * By switching maybe_redirect_404() to catch at a higher priority, we avoid
 * the race condition. If bp_core_load_template() runs, it dies before reaching
 * maybe_redirect_404(). If bp_core_load_template() does not run, it means that
 * the 404 is legitimate, and maybe_redirect_404() can proceed as expected.
 *
 * This function will be removed in a later version of BuddyPress. Plugins
 * (and plugin authors!) should ignore it.
 *
 * @since 1.6.1
 *
 * @link http://buddypress.trac.wordpress.org/ticket/4329
 * @link http://buddypress.trac.wordpress.org/ticket/4415
 */
function _bp_rehook_maybe_redirect_404() {
    if ( defined( 'NOBLOGREDIRECT' ) ) {
        remove_action( 'template_redirect', 'maybe_redirect_404' );
        add_action( 'template_redirect', 'maybe_redirect_404', 100 );
    }
}
add_action( 'template_redirect', '_bp_rehook_maybe_redirect_404', 1 );

/**
 * Remove WordPress's rel=canonical HTML tag if we are trying to load BuddyPress
 * specific content.
 *
 * This function should be considered temporary, and may be removed without
 * notice in future versions of BuddyPress.
 *
 * @since 1.6
 */
function _bp_maybe_remove_rel_canonical() {
    if ( ! bp_is_blog_page() && ! is_404() ) {
        remove_action( 'wp_head', 'rel_canonical' );
        add_action( 'bp_head', 'bp_rel_canonical' );
    }
}
add_action( 'wp_head', '_bp_maybe_remove_rel_canonical', 8 );
?>