civicrm-multisite-domain-config.php

<?php

/**
 * Define CiviCRM Multisite Domain constants and settings.
 *
 * When a WordPress site is accessed, CiviCRM needs to know a number of settings
 * that enable Multisite Domain functionality. Define that data here.
 *
 * Once the Domain has been created (e.g. via the form on the "Domains" tab of
 * the CiviCRM Admin Utilities network settings page) add the corresponding data
 * array for the Domain to the array below. The four uncommented entries are 
 * required. Do this *before* enabling CiviCRM on the WordPress sub-site.
 *
 * The good thing about separating this functionality out in this way is that we
 * can now read the correspondences between WordPress sites and CiviCRM Domains.
 * The main array is keyed by the `home_url()` of the relevant WordPress site.
 *
 * If you want easy access to the `domain_group_id` and/or the `domain_org_id` for
 * a WordPress site, then these can be filled out and uncommented, though they are 
 * not strictly necessary for multiple CiviCRM Domains to work and can be discovered
 * by other means.
 *
 * @return array $data The CiviCRM Multisite Domain data.
 */
function civicrm_multisite_get_domain_data() {

	// Define CiviCRM Multisite Domain data.
	$data = array(

		// Always put the data for the main site first.
		'http://civicrm.multisite.stable' => array(
			'domain_id' => 1,
			//'domain_group_id' => 5, // Uncomment if required by other plugins.
			//'domain_org_id' => 1, // Uncomment if required by other plugins.
			'extensionsDir' => '/path/to/civicrm.multisite.stable/httpdocs/wp-content/uploads/civicrm/ext/',
			'extensionsURL' => 'http://civicrm.multisite.stable/wp-content/uploads/civicrm/ext/',
			'userFrameworkResourceURL' => 'http://civicrm.multisite.stable/wp-content/plugins/civicrm/civicrm/',
		),

		// Add sub-sites after the main site.
		'http://civicrm.multisite.stable/first' => array(
			'domain_id' => 2,
			//'domain_group_id' => 6, // Uncomment if required by other plugins.
			//'domain_org_id' => 203, // Uncomment if required by other plugins.
			'extensionsDir' => '/path/to/civicrm.multisite.stable/httpdocs/wp-content/uploads/civicrm/ext/',
			'extensionsURL' => 'http://civicrm.multisite.stable/first/wp-content/uploads/civicrm/ext/',
			'userFrameworkResourceURL' => 'http://civicrm.multisite.stable/first/wp-content/plugins/civicrm/civicrm/',
		),

	);

	// --<
	return $data;

}



/**
 * Get the URL for the requested WordPress site.
 *
 * @return str $url The URL for the requested WordPress site.
 */
function civicrm_multisite_get_url_from_server_vars() {

	// We first need to find the URL of the current site.
	if ( function_exists( 'home_url' ) ) {

		// When WordPress is bootstrapped, this is always correct.
		$url = home_url();

	} else {

		/*
		 * The following code deals with WordPress multisite when it is configured
		 * for sub-directories.
		 *
		 * If your multisite uses subdomains and you are not routing all calls to 
		 * CiviCRM via WordPress (e.g. by using WP-REST instead of `extern/*.php` 
		 * or `bin/*.php`) then you'll have to amend this.
		 *
		 * Q: How do we discover sub-directory paths from $_SERVER alone?
		 * A: There isn't a reliable way unless all sites are known.
		 *
		 * The true solution to this guesswork is never to bootstrap CiviCRM except
		 * via WordPress. I'm looking at you `extern/*.php`.
		 *
		 * tl;dr Always route via WordPress.
		 */

		// Protocol is easy:
		$protocol = strstr( 'HTTPS', $_SERVER['SERVER_PROTOCOL'] ) ? 'https://' : 'http://';

		// Get "site path" - the first part of the path.
		$path = '';
		if ( ! empty( $_SERVER['REQUEST_URI'] ) ) {
			$tmp_path = explode( '/', $_SERVER['REQUEST_URI'] );
			$path = isset( $tmp_path[0] ) ? '/' . $tmp_path[0] : '';
		}

		// Put it all together.
		$url = $protocol . $_SERVER['SERVER_NAME'] . $path;

	}

	// --<
	return $url;

}


/**
 * Set CiviCRM Multisite Domain constants and settings.
 *
 * When a WordPress site is accessed, CiviCRM needs to know what Domain is being
 * accessed. This is far from trivial :(
 */
function civicrm_multisite_set_domain_data_for_site() {

	// We need access to some CiviCRM globals.
	global $civicrm_setting, $civicrm_paths;

	// Get the URL for the requested site.
	$url = civicrm_multisite_get_url_from_server_vars();

	// Get CiviCRM data.
	$data = civicrm_multisite_get_domain_data();

	// Use Main Site if we don't have an entry.
	if ( empty( $data[$url] ) ) {
		$settings = array_shift( $data );
	} else {
		$settings = $data[$url];
	}

	// Always set the Base URL.
	define( 'CIVICRM_UF_BASEURL', $url );

	// Set the CiviCRM Domain ID.
	if ( isset( $settings['domain_id'] ) ) {
		define( 'CIVICRM_DOMAIN_ID', $settings['domain_id'] );
	}
	
	// CiviCRM does not need these two constants, but you may wish to set them for reference.
	if ( isset( $settings['domain_group_id'] ) ) {
		define( 'CIVICRM_DOMAIN_GROUP_ID', $settings['domain_group_id'] );
	}
	if ( isset( $settings['domain_org_id'] ) ) {
		define( 'CIVICRM_DOMAIN_ORG_ID', $settings['domain_org_id'] );
	}
	
	// These paths are crucial for CiviCRM.
	if ( isset( $settings['extensionsDir'] ) ) {
		$civicrm_setting['domain']['extensionsDir'] = $settings['extensionsDir'];
	}
	if ( isset( $settings['extensionsURL'] ) ) {
		$civicrm_setting['domain']['extensionsURL'] = $settings['extensionsURL'];
	}
	if ( isset( $settings['userFrameworkResourceURL'] ) ) {
		$civicrm_setting['domain']['userFrameworkResourceURL'] = $settings['userFrameworkResourceURL'];
	}

}

// Trigger Multisite discovery immediately.
civicrm_multisite_set_domain_data_for_site();