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wp-includes/https-detection.php

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+<?php
+/**
+ * HTTPS detection functions.
+ *
+ * @package WordPress
+ * @since 5.7.0
+ */
+
+/**
+ * Checks whether the website is using HTTPS.
+ *
+ * This is based on whether both the home and site URL are using HTTPS.
+ *
+ * @since 5.7.0
+ * @see wp_is_home_url_using_https()
+ * @see wp_is_site_url_using_https()
+ *
+ * @return bool True if using HTTPS, false otherwise.
+ */
+function wp_is_using_https() {
+	if ( ! wp_is_home_url_using_https() ) {
+		return false;
+	}
+
+	return wp_is_site_url_using_https();
+}
+
+/**
+ * Checks whether the current site URL is using HTTPS.
+ *
+ * @since 5.7.0
+ * @see home_url()
+ *
+ * @return bool True if using HTTPS, false otherwise.
+ */
+function wp_is_home_url_using_https() {
+	return 'https' === wp_parse_url( home_url(), PHP_URL_SCHEME );
+}
+
+/**
+ * Checks whether the current site's URL where WordPress is stored is using HTTPS.
+ *
+ * This checks the URL where WordPress application files (e.g. wp-blog-header.php or the wp-admin/ folder)
+ * are accessible.
+ *
+ * @since 5.7.0
+ * @see site_url()
+ *
+ * @return bool True if using HTTPS, false otherwise.
+ */
+function wp_is_site_url_using_https() {
+	/*
+	 * Use direct option access for 'siteurl' and manually run the 'site_url'
+	 * filter because `site_url()` will adjust the scheme based on what the
+	 * current request is using.
+	 */
+	/** This filter is documented in wp-includes/link-template.php */
+	$site_url = apply_filters( 'site_url', get_option( 'siteurl' ), '', null, null );
+
+	return 'https' === wp_parse_url( $site_url, PHP_URL_SCHEME );
+}
+
+/**
+ * Checks whether HTTPS is supported for the server and domain.
+ *
+ * @since 5.7.0
+ *
+ * @return bool True if HTTPS is supported, false otherwise.
+ */
+function wp_is_https_supported() {
+	$https_detection_errors = get_option( 'https_detection_errors' );
+
+	// If option has never been set by the Cron hook before, run it on-the-fly as fallback.
+	if ( false === $https_detection_errors ) {
+		wp_update_https_detection_errors();
+
+		$https_detection_errors = get_option( 'https_detection_errors' );
+	}
+
+	// If there are no detection errors, HTTPS is supported.
+	return empty( $https_detection_errors );
+}
+
+/**
+ * Runs a remote HTTPS request to detect whether HTTPS supported, and stores potential errors.
+ *
+ * This internal function is called by a regular Cron hook to ensure HTTPS support is detected and maintained.
+ *
+ * @since 6.4.0
+ * @access private
+ */
+function wp_get_https_detection_errors() {
+	/**
+	 * Short-circuits the process of detecting errors related to HTTPS support.
+	 *
+	 * Returning a `WP_Error` from the filter will effectively short-circuit the default logic of trying a remote
+	 * request to the site over HTTPS, storing the errors array from the returned `WP_Error` instead.
+	 *
+	 * @since 6.4.0
+	 *
+	 * @param null|WP_Error $pre Error object to short-circuit detection,
+	 *                           or null to continue with the default behavior.
+	 * @return null|WP_Error Error object if HTTPS detection errors are found, null otherwise.
+	 */
+	$support_errors = apply_filters( 'pre_wp_get_https_detection_errors', null );
+	if ( is_wp_error( $support_errors ) ) {
+		return $support_errors->errors;
+	}
+
+	$support_errors = new WP_Error();
+
+	$response = wp_remote_request(
+		home_url( '/', 'https' ),
+		array(
+			'headers'   => array(
+				'Cache-Control' => 'no-cache',
+			),
+			'sslverify' => true,
+		)
+	);
+
+	if ( is_wp_error( $response ) ) {
+		$unverified_response = wp_remote_request(
+			home_url( '/', 'https' ),
+			array(
+				'headers'   => array(
+					'Cache-Control' => 'no-cache',
+				),
+				'sslverify' => false,
+			)
+		);
+
+		if ( is_wp_error( $unverified_response ) ) {
+			$support_errors->add(
+				'https_request_failed',
+				__( 'HTTPS request failed.' )
+			);
+		} else {
+			$support_errors->add(
+				'ssl_verification_failed',
+				__( 'SSL verification failed.' )
+			);
+		}
+
+		$response = $unverified_response;
+	}
+
+	if ( ! is_wp_error( $response ) ) {
+		if ( 200 !== wp_remote_retrieve_response_code( $response ) ) {
+			$support_errors->add( 'bad_response_code', wp_remote_retrieve_response_message( $response ) );
+		} elseif ( false === wp_is_local_html_output( wp_remote_retrieve_body( $response ) ) ) {
+			$support_errors->add( 'bad_response_source', __( 'It looks like the response did not come from this site.' ) );
+		}
+	}
+
+	return $support_errors->errors;
+}
+
+/**
+ * Checks whether a given HTML string is likely an output from this WordPress site.
+ *
+ * This function attempts to check for various common WordPress patterns whether they are included in the HTML string.
+ * Since any of these actions may be disabled through third-party code, this function may also return null to indicate
+ * that it was not possible to determine ownership.
+ *
+ * @since 5.7.0
+ * @access private
+ *
+ * @param string $html Full HTML output string, e.g. from a HTTP response.
+ * @return bool|null True/false for whether HTML was generated by this site, null if unable to determine.
+ */
+function wp_is_local_html_output( $html ) {
+	// 1. Check if HTML includes the site's Really Simple Discovery link.
+	if ( has_action( 'wp_head', 'rsd_link' ) ) {
+		$pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( site_url( 'xmlrpc.php?rsd', 'rpc' ) ) ); // See rsd_link().
+		return str_contains( $html, $pattern );
+	}
+
+	// 2. Check if HTML includes the site's REST API link.
+	if ( has_action( 'wp_head', 'rest_output_link_wp_head' ) ) {
+		// Try both HTTPS and HTTP since the URL depends on context.
+		$pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( get_rest_url() ) ); // See rest_output_link_wp_head().
+		return str_contains( $html, $pattern );
+	}
+
+	// Otherwise the result cannot be determined.
+	return null;
+}