WordPress at a glance
function is not described

wp_http_supports() WP 3.2.0

Determines if there is an HTTP Transport that can process this request.

No Hooks.

Return

true/false.

Usage

wp_http_supports( $capabilities, $url );
$capabilities(array)
Array of capabilities to test or a wp_remote_request() $args array.
Default: array()
$url(string)
If given, will check if the URL requires SSL and adds that requirement to the capabilities array.
Default: null

Code of wp http supports: wp-includes/http.php VER 5.0.3

<?php
function wp_http_supports( $capabilities = array(), $url = null ) {
	$http = _wp_http_get_object();

	$capabilities = wp_parse_args( $capabilities );

	$count = count( $capabilities );

	// If we have a numeric $capabilities array, spoof a wp_remote_request() associative $args array
	if ( $count && count( array_filter( array_keys( $capabilities ), 'is_numeric' ) ) == $count ) {
		$capabilities = array_combine( array_values( $capabilities ), array_fill( 0, $count, true ) );
	}

	if ( $url && !isset( $capabilities['ssl'] ) ) {
		$scheme = parse_url( $url, PHP_URL_SCHEME );
		if ( 'https' == $scheme || 'ssl' == $scheme ) {
			$capabilities['ssl'] = true;
		}
	}

	return (bool) $http->_get_first_available_transport( $capabilities );
}