Replace site_url in posts syndicated by WP Broadcast

broadcast-replace-site_url.php

<?

/**
 * Hook into Broadcast
 * Modify links in the broadcasted post content
 * "Replace Site URL" checkbox appears in child post meta box to show if this was applied
 */
add_action( 'threewp_broadcast_prepare_meta_box', 'my_custom_prepare_meta_box' );
function my_custom_prepare_meta_box( $action ) {
	$meta_box_data = $action->meta_box_data;	// Convenience.
	$form = $meta_box_data->form;				// Convenience
	$form->prefix( 'broadcast' );				// Create all inputs with this prefix.

	if ( is_super_admin() OR $this->user_has_roles( $this->get_site_option( 'role_link' ) ) ) {
		// "Replace Site URL" should be checked by default
		$checked = 'add' == get_current_screen()->action ? true : 'on' == get_post_meta( $meta_box_data->post_id, '_my_custom_broadcast_replace_site_url', true );
		$site_url_input = $form->checkbox( 'replace_site_url' )
			->checked( $checked )
			// Input label for meta box
			->label( __( 'Replace Site URL', 'my_custom' ) )
			// Input title for meta box
			->title( __( 'Replace the domain name in links to match the child site URL.', 'my_custom' ) );
		$meta_box_data->convert_form_input_later( 'replace_site_url' );
	}
}

add_action( 'threewp_broadcast_broadcasting_modify_post', 'my_custom_broadcasting_modify_post', 20 );
function my_custom_broadcasting_modify_post( $action ) {
	$bcd = $action->broadcasting_data;
	$form = $bcd->meta_box_data->form;
	$replace_site_url = $form->checkbox( 'replace_site_url' )->get_post_value(); // 'on' or NULL

	if ( $replace_site_url ) {
		$parent_site_url = get_site_url( $bcd->parent_blog_id );
		$child_site_url = get_site_url( $bcd->current_child_blog_id );
		$modified_content = $bcd->modified_post->post_content;
		$modified_content = str_replace( $parent_site_url, $child_site_url, $modified_content );
		$bcd->modified_post->post_content = $modified_content;
	}

	// Update our custom Broadcast option meta field value…
	$_my_custom_broadcast_replace_site_url = $replace_site_url ? 'on' : 'off';
	$bcd->custom_fields->original[ '_my_custom_broadcast_replace_site_url' ] = $_my_custom_broadcast_replace_site_url;
	// …and on parent site
	switch_to_blog( $bcd->parent_blog_id );
	update_post_meta(
		$bcd->broadcast_data->post_id,
		'_my_custom_broadcast_replace_site_url',
		$_my_custom_broadcast_replace_site_url
	);
	restore_current_blog();
}

This is exactly the solution we needed for a customer of ours.

Many thanks and greetings from pxMEDIA.