Source

File: wp-admin/includes/plugin-install.php

function plugins_api( $action, $args = array() ) {
	// Include an unmodified $wp_version.
	require ABSPATH . WPINC . '/version.php';

	if ( is_array( $args ) ) {
		$args = (object) $args;
	}

	if ( 'query_plugins' === $action ) {
		if ( ! isset( $args->per_page ) ) {
			$args->per_page = 24;
		}
	}

	if ( ! isset( $args->locale ) ) {
		$args->locale = get_user_locale();
	}

	if ( ! isset( $args->wp_version ) ) {
		$args->wp_version = substr( $wp_version, 0, 3 ); // x.y
	}

	/**
	 * Filters the WordPress.org Plugin Installation API arguments.
	 *
	 * Important: An object MUST be returned to this filter.
	 *
	 * @since 2.7.0
	 *
	 * @param object $args   Plugin API arguments.
	 * @param string $action The type of information being requested from the Plugin Installation API.
	 */
	$args = apply_filters( 'plugins_api_args', $args, $action );

	/**
	 * Filters the response for the current WordPress.org Plugin Installation API request.
	 *
	 * Passing a non-false value will effectively short-circuit the WordPress.org API request.
	 *
	 * If `$action` is 'query_plugins' or 'plugin_information', an object MUST be passed.
	 * If `$action` is 'hot_tags' or 'hot_categories', an array should be passed.
	 *
	 * @since 2.7.0
	 *
	 * @param false|object|array $result The result object or array. Default false.
	 * @param string             $action The type of information being requested from the Plugin Installation API.
	 * @param object             $args   Plugin API arguments.
	 */
	$res = apply_filters( 'plugins_api', false, $action, $args );

	if ( false === $res ) {

		$url = 'http://api.wordpress.org/plugins/info/1.2/';
		$url = add_query_arg(
			array(
				'action'  => $action,
				'request' => $args,
			),
			$url
		);

		$http_url = $url;
		$ssl      = wp_http_supports( array( 'ssl' ) );
		if ( $ssl ) {
			$url = set_url_scheme( $url, 'https' );
		}

		$http_args = array(
			'timeout'    => 15,
			'user-agent' => 'WordPress/' . $wp_version . '; ' . home_url( '/' ),
		);
		$request   = wp_remote_get( $url, $http_args );

		if ( $ssl && is_wp_error( $request ) ) {
			if ( ! wp_is_json_request() ) {
				trigger_error(
					sprintf(
						/* translators: %s: Support forums URL. */
						__( 'An unexpected error occurred. Something may be wrong with WordPress.org or this server&#8217;s configuration. If you continue to have problems, please try the <a href="%s">support forums</a>.' ),
						__( 'https://wordpress.org/support/forums/' )
					) . ' ' . __( '(WordPress could not establish a secure connection to WordPress.org. Please contact your server administrator.)' ),
					headers_sent() || WP_DEBUG ? E_USER_WARNING : E_USER_NOTICE
				);
			}

			$request = wp_remote_get( $http_url, $http_args );
		}

		if ( is_wp_error( $request ) ) {
			$res = new WP_Error(
				'plugins_api_failed',
				sprintf(
					/* translators: %s: Support forums URL. */
					__( 'An unexpected error occurred. Something may be wrong with WordPress.org or this server&#8217;s configuration. If you continue to have problems, please try the <a href="%s">support forums</a>.' ),
					__( 'https://wordpress.org/support/forums/' )
				),
				$request->get_error_message()
			);
		} else {
			$res = json_decode( wp_remote_retrieve_body( $request ), true );
			if ( is_array( $res ) ) {
				// Object casting is required in order to match the info/1.0 format.
				$res = (object) $res;
			} elseif ( null === $res ) {
				$res = new WP_Error(
					'plugins_api_failed',
					sprintf(
						/* translators: %s: Support forums URL. */
						__( 'An unexpected error occurred. Something may be wrong with WordPress.org or this server&#8217;s configuration. If you continue to have problems, please try the <a href="%s">support forums</a>.' ),
						__( 'https://wordpress.org/support/forums/' )
					),
					wp_remote_retrieve_body( $request )
				);
			}

			if ( isset( $res->error ) ) {
				$res = new WP_Error( 'plugins_api_failed', $res->error );
			}
		}
	} elseif ( ! is_wp_error( $res ) ) {
		$res->external = true;
	}

	/**
	 * Filters the Plugin Installation API response results.
	 *
	 * @since 2.7.0
	 *
	 * @param object|WP_Error $res    Response object or WP_Error.
	 * @param string          $action The type of information being requested from the Plugin Installation API.
	 * @param object          $args   Plugin API arguments.
	 */
	return apply_filters( 'plugins_api_result', $res, $action, $args );
}