src/functions.php

<?php
namespace GuzzleHttp;

use GuzzleHttp\Handler\CurlHandler;
use GuzzleHttp\Handler\CurlMultiHandler;
use GuzzleHttp\Handler\Proxy;
use GuzzleHttp\Handler\StreamHandler;
use Psr\Http\Message\StreamInterface;

/**
 * Expands a URI template
 *
 * @param string $template  URI template
 * @param array  $variables Template variables
 *
 * @return string
 */
function uri_template($template, array $variables)
{
    if (extension_loaded('uri_template')) {
        // @codeCoverageIgnoreStart
        return \uri_template($template, $variables);
        // @codeCoverageIgnoreEnd
    }

    static $uriTemplate;
    if (!$uriTemplate) {
        $uriTemplate = new UriTemplate();
    }

    return $uriTemplate->expand($template, $variables);
}

/**
 * Debug function used to describe the provided value type and class.
 *
 * @param mixed $input
 *
 * @return string Returns a string containing the type of the variable and
 *                if a class is provided, the class name.
 */
function describe_type($input)
{
    switch (gettype($input)) {
        case 'object':
            return 'object(' . get_class($input) . ')';
        case 'array':
            return 'array(' . count($input) . ')';
        default:
            ob_start();
            var_dump($input);
            // normalize float vs double
            return str_replace('double(', 'float(', rtrim(ob_get_clean()));
    }
}

/**
 * Parses an array of header lines into an associative array of headers.
 *
 * @param array $lines Header lines array of strings in the following
 *                     format: "Name: Value"
 * @return array
 */
function headers_from_lines($lines)
{
    $headers = [];

    foreach ($lines as $line) {
        $parts = explode(':', $line, 2);
        $headers[trim($parts[0])][] = isset($parts[1])
            ? trim($parts[1])
            : null;
    }

    return $headers;
}

/**
 * Returns a debug stream based on the provided variable.
 *
 * @param mixed $value Optional value
 *
 * @return resource
 */
function debug_resource($value = null)
{
    if (is_resource($value)) {
        return $value;
    } elseif (defined('STDOUT')) {
        return STDOUT;
    }

    return fopen('php://output', 'w');
}

/**
 * Chooses and creates a default handler to use based on the environment.
 *
 * The returned handler is not wrapped by any default middlewares.
 *
 * @throws \RuntimeException if no viable Handler is available.
 * @return callable Returns the best handler for the given system.
 */
function choose_handler()
{
    $handler = null;
    if (extension_loaded('curl')) {
        $handler = Proxy::wrapSync(new CurlMultiHandler(), new CurlHandler());
    }

    if (ini_get('allow_url_fopen')) {
        $handler = $handler
            ? Proxy::wrapStreaming($handler, new StreamHandler())
            : new StreamHandler();
    } elseif (!$handler) {
        throw new \RuntimeException('GuzzleHttp requires cURL, the '
            . 'allow_url_fopen ini setting, or a custom HTTP handler.');
    }

    return $handler;
}

/**
 * Get the default User-Agent string to use with Guzzle
 *
 * @return string
 */
function default_user_agent()
{
    static $defaultAgent = '';

    if (!$defaultAgent) {
        $defaultAgent = 'GuzzleHttp/' . Client::VERSION;
        if (extension_loaded('curl')) {
            $defaultAgent .= ' curl/' . \curl_version()['version'];
        }
        $defaultAgent .= ' PHP/' . PHP_VERSION;
    }

    return $defaultAgent;
}

/**
 * Returns the default cacert bundle for the current system.
 *
 * First, the openssl.cafile and curl.cainfo php.ini settings are checked.
 * If those settings are not configured, then the common locations for
 * bundles found on Red Hat, CentOS, Fedora, Ubuntu, Debian, FreeBSD, OS X
 * and Windows are checked. If any of these file locations are found on
 * disk, they will be utilized.
 *
 * Note: the result of this function is cached for subsequent calls.
 *
 * @return string
 * @throws \RuntimeException if no bundle can be found.
 */
function default_ca_bundle()
{
    static $cached = null;
    static $cafiles = [
        // Red Hat, CentOS, Fedora (provided by the ca-certificates package)
        '/etc/pki/tls/certs/ca-bundle.crt',
        // Ubuntu, Debian (provided by the ca-certificates package)
        '/etc/ssl/certs/ca-certificates.crt',
        // FreeBSD (provided by the ca_root_nss package)
        '/usr/local/share/certs/ca-root-nss.crt',
        // OS X provided by homebrew (using the default path)
        '/usr/local/etc/openssl/cert.pem',
        // Windows?
        'C:\\windows\\system32\\curl-ca-bundle.crt',
        'C:\\windows\\curl-ca-bundle.crt',
    ];

    if ($cached) {
        return $cached;
    }

    if ($ca = ini_get('openssl.cafile')) {
        return $cached = $ca;
    }

    if ($ca = ini_get('curl.cainfo')) {
        return $cached = $ca;
    }

    foreach ($cafiles as $filename) {
        if (file_exists($filename)) {
            return $cached = $filename;
        }
    }

    throw new \RuntimeException(<<< EOT
No system CA bundle could be found in any of the the common system locations.
PHP versions earlier than 5.6 are not properly configured to use the system's
CA bundle by default. In order to verify peer certificates, you will need to
supply the path on disk to a certificate bundle to the 'verify' request
option: http://docs.guzzlephp.org/en/latest/clients.html#verify. If you do not
need a specific certificate bundle, then Mozilla provides a commonly used CA
bundle which can be downloaded here (provided by the maintainer of cURL):
https://raw.githubusercontent.com/bagder/ca-bundle/master/ca-bundle.crt. Once
you have a CA bundle available on disk, you can set the 'openssl.cafile' PHP
ini setting to point to the path to the file, allowing you to omit the 'verify'
request option. See http://curl.haxx.se/docs/sslcerts.html for more
information.
EOT
    );
}

/**
 * Creates an associative array of lowercase header names to the actual
 * header casing.
 *
 * @param array $headers
 *
 * @return array
 */
function normalize_header_keys(array $headers)
{
    $result = [];
    foreach (array_keys($headers) as $key) {
        $result[strtolower($key)] = $key;
    }

    return $result;
}