PHP Example¶
example.php¶
<?php
require("OAuth.php");
$cc_key = "CLIENT_KEY_HERE";
$cc_secret = "CLIENT_SECRET_HERE";
$url = "https://api.thenounproject.com/v2/icon";
$args = array();
$args["query"] = "happy";
$args["limit"] = 10;
$consumer = new OAuthConsumer($cc_key, $cc_secret);
$request = OAuthRequest::from_consumer_and_token($consumer, NULL,"GET", $url, $args);
$request->sign_request(new OAuthSignatureMethod_HMAC_SHA1(), $consumer, NULL);
$url = sprintf("%s?%s", $url, OAuthUtil::build_http_query($args));
$ch = curl_init();
$headers = array($request->to_header());
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
$rsp = curl_exec($ch);
print_r($rsp)
?>
OAuth.php¶
<?php
class OAuthException extends Exception
{
// pass
}
class OAuthConsumer
{
public $key;
public $secret;
function __construct($key, $secret, $callback_url = null)
{
$this->key = $key;
$this->secret = $secret;
$this->callback_url = $callback_url;
}
function __toString()
{
return "OAuthConsumer[key=$this->key,secret=$this->secret]";
}
}
class OAuthToken
{
// access tokens and request tokens
public $key;
public $secret;
/**
* key = the token
* secret = the token secret
*/
function __construct($key, $secret)
{
$this->key = $key;
$this->secret = $secret;
}
/**
* generates the basic string serialization of a token that a server
* would respond to request_token and access_token calls with
*/
function to_string()
{
return "oauth_token=" .
OAuthUtil::urlencode_rfc3986($this->key) .
"&oauth_token_secret=" .
OAuthUtil::urlencode_rfc3986($this->secret);
}
function __toString()
{
return $this->to_string();
}
}
/**
* A class for implementing a Signature Method
* See section 9 ("Signing Requests") in the spec
*/
abstract class OAuthSignatureMethod
{
/**
* Needs to return the name of the Signature Method (ie HMAC-SHA1)
* @return string
*/
abstract public function get_name();
/**
* Build up the signature
* NOTE: The output of this function MUST NOT be urlencoded.
* the encoding is handled in OAuthRequest when the final
* request is serialized
* @param OAuthRequest $request
* @param OAuthConsumer $consumer
* @param OAuthToken $token
* @return string
*/
abstract public function build_signature($request, $consumer, $token);
/**
* Verifies that a given signature is correct
* @param OAuthRequest $request
* @param OAuthConsumer $consumer
* @param OAuthToken $token
* @param string $signature
* @return bool
*/
public function check_signature($request, $consumer, $token, $signature)
{
$built = $this->build_signature($request, $consumer, $token);
// Check for zero length, although unlikely here
if (strlen($built) == 0 || strlen($signature) == 0) {
return false;
}
if (strlen($built) != strlen($signature)) {
return false;
}
// Avoid a timing leak with a (hopefully) time insensitive compare
$result = 0;
for ($i = 0; $i < strlen($signature); $i++) {
$result |= ord($built[$i]) ^ ord($signature[$i]);
}
return $result == 0;
}
}
/**
* The HMAC-SHA1 signature method uses the HMAC-SHA1 signature algorithm as defined in [RFC2104]
* where the Signature Base String is the text and the key is the concatenated values (each first
* encoded per Parameter Encoding) of the Consumer Secret and Token Secret, separated by an '&'
* character (ASCII code 38) even if empty.
* - Chapter 9.2 ("HMAC-SHA1")
*/
class OAuthSignatureMethod_HMAC_SHA1 extends OAuthSignatureMethod
{
function get_name()
{
return "HMAC-SHA1";
}
public function build_signature($request, $consumer, $token)
{
$base_string = $request->get_signature_base_string();
$request->base_string = $base_string;
$key_parts = [$consumer->secret, $token ? $token->secret : ""];
$key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
$key = implode("&", $key_parts);
return base64_encode(hash_hmac("sha1", $base_string, $key, true));
}
}
/**
* The PLAINTEXT method does not provide any security protection and SHOULD only be used
* over a secure channel such as HTTPS. It does not use the Signature Base String.
* - Chapter 9.4 ("PLAINTEXT")
*/
class OAuthSignatureMethod_PLAINTEXT extends OAuthSignatureMethod
{
public function get_name()
{
return "PLAINTEXT";
}
/**
* oauth_signature is set to the concatenated encoded values of the Consumer Secret and
* Token Secret, separated by a '&' character (ASCII code 38), even if either secret is
* empty. The result MUST be encoded again.
* - Chapter 9.4.1 ("Generating Signatures")
*
* Please note that the second encoding MUST NOT happen in the SignatureMethod, as
* OAuthRequest handles this!
*/
public function build_signature($request, $consumer, $token)
{
$key_parts = [$consumer->secret, $token ? $token->secret : ""];
$key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
$key = implode("&", $key_parts);
$request->base_string = $key;
return $key;
}
}
/**
* The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature algorithm as defined in
* [RFC3447] section 8.2 (more simply known as PKCS#1), using SHA-1 as the hash function for
* EMSA-PKCS1-v1_5. It is assumed that the Consumer has provided its RSA public key in a
* verified way to the Service Provider, in a manner which is beyond the scope of this
* specification.
* - Chapter 9.3 ("RSA-SHA1")
*/
abstract class OAuthSignatureMethod_RSA_SHA1 extends OAuthSignatureMethod
{
public function get_name()
{
return "RSA-SHA1";
}
// Up to the SP to implement this lookup of keys. Possible ideas are:
// (1) do a lookup in a table of trusted certs keyed off of consumer
// (2) fetch via http using a url provided by the requester
// (3) some sort of specific discovery code based on request
//
// Either way should return a string representation of the certificate
abstract protected function fetch_public_cert(&$request);
// Up to the SP to implement this lookup of keys. Possible ideas are:
// (1) do a lookup in a table of trusted certs keyed off of consumer
//
// Either way should return a string representation of the certificate
abstract protected function fetch_private_cert(&$request);
public function build_signature($request, $consumer, $token)
{
$base_string = $request->get_signature_base_string();
$request->base_string = $base_string;
// Fetch the private key cert based on the request
$cert = $this->fetch_private_cert($request);
// Pull the private key ID from the certificate
$privatekeyid = openssl_get_privatekey($cert);
// Sign using the key
$ok = openssl_sign($base_string, $signature, $privatekeyid);
// Release the key resource
openssl_free_key($privatekeyid);
return base64_encode($signature);
}
public function check_signature($request, $consumer, $token, $signature)
{
$decoded_sig = base64_decode($signature);
$base_string = $request->get_signature_base_string();
// Fetch the public key cert based on the request
$cert = $this->fetch_public_cert($request);
// Pull the public key ID from the certificate
$publickeyid = openssl_get_publickey($cert);
// Check the computed signature against the one passed in the query
$ok = openssl_verify($base_string, $decoded_sig, $publickeyid);
// Release the key resource
openssl_free_key($publickeyid);
return $ok == 1;
}
}
class OAuthRequest
{
protected $parameters;
protected $http_method;
protected $http_url;
// for debug purposes
public $base_string;
public static $version = "1.0";
public static $POST_INPUT = "php://input";
function __construct($http_method, $http_url, $parameters = null)
{
$parameters = $parameters ? $parameters : [];
$parameters = array_merge(
OAuthUtil::parse_parameters(parse_url($http_url, PHP_URL_QUERY)),
$parameters
);
$this->parameters = $parameters;
$this->http_method = $http_method;
$this->http_url = $http_url;
}
/**
* attempt to build up a request from what was passed to the server
*/
public static function from_request(
$http_method = null,
$http_url = null,
$parameters = null
) {
$scheme =
!isset($_SERVER["HTTPS"]) || $_SERVER["HTTPS"] != "on"
? "http"
: "https";
$http_url = $http_url
? $http_url
: $scheme .
"://" .
$_SERVER["SERVER_NAME"] .
":" .
$_SERVER["SERVER_PORT"] .
$_SERVER["REQUEST_URI"];
$http_method = $http_method ? $http_method : $_SERVER["REQUEST_METHOD"];
// We weren't handed any parameters, so let's find the ones relevant to
// this request.
// If you run XML-RPC or similar you should use this to provide your own
// parsed parameter-list
if (!$parameters) {
// Find request headers
$request_headers = OAuthUtil::get_headers();
// Parse the query-string to find GET parameters
$parameters = OAuthUtil::parse_parameters($_SERVER["QUERY_STRING"]);
// It's a POST request of the proper content-type, so parse POST
// parameters and add those overriding any duplicates from GET
if (
$http_method == "POST" &&
isset($request_headers["Content-Type"]) &&
strstr(
$request_headers["Content-Type"],
"application/x-www-form-urlencoded"
)
) {
$post_data = OAuthUtil::parse_parameters(
file_get_contents(self::$POST_INPUT)
);
$parameters = array_merge($parameters, $post_data);
}
// We have a Authorization-header with OAuth data. Parse the header
// and add those overriding any duplicates from GET or POST
if (
isset($request_headers["Authorization"]) &&
substr($request_headers["Authorization"], 0, 6) == "OAuth "
) {
$header_parameters = OAuthUtil::split_header(
$request_headers["Authorization"]
);
$parameters = array_merge($parameters, $header_parameters);
}
}
return new OAuthRequest($http_method, $http_url, $parameters);
}
/**
* pretty much a helper function to set up the request
*/
public static function from_consumer_and_token(
$consumer,
$token,
$http_method,
$http_url,
$parameters = null
) {
$parameters = $parameters ? $parameters : [];
$defaults = [
"oauth_version" => OAuthRequest::$version,
"oauth_nonce" => OAuthRequest::generate_nonce(),
"oauth_timestamp" => OAuthRequest::generate_timestamp(),
"oauth_consumer_key" => $consumer->key,
];
if ($token) {
$defaults["oauth_token"] = $token->key;
}
$parameters = array_merge($defaults, $parameters);
return new OAuthRequest($http_method, $http_url, $parameters);
}
public function set_parameter($name, $value, $allow_duplicates = true)
{
if ($allow_duplicates && isset($this->parameters[$name])) {
// We have already added parameter(s) with this name, so add to the list
if (is_scalar($this->parameters[$name])) {
// This is the first duplicate, so transform scalar (string)
// into an array so we can add the duplicates
$this->parameters[$name] = [$this->parameters[$name]];
}
$this->parameters[$name][] = $value;
} else {
$this->parameters[$name] = $value;
}
}
public function get_parameter($name)
{
return isset($this->parameters[$name])
? $this->parameters[$name]
: null;
}
public function get_parameters()
{
return $this->parameters;
}
public function unset_parameter($name)
{
unset($this->parameters[$name]);
}
/**
* The request parameters, sorted and concatenated into a normalized string.
* @return string
*/
public function get_signable_parameters()
{
// Grab all parameters
$params = $this->parameters;
// Remove oauth_signature if present
// Ref: Spec: 9.1.1 ("The oauth_signature parameter MUST be excluded.")
if (isset($params["oauth_signature"])) {
unset($params["oauth_signature"]);
}
return OAuthUtil::build_http_query($params);
}
/**
* Returns the base string of this request
*
* The base string defined as the method, the url
* and the parameters (normalized), each urlencoded
* and the concated with &.
*/
public function get_signature_base_string()
{
$parts = [
$this->get_normalized_http_method(),
$this->get_normalized_http_url(),
$this->get_signable_parameters(),
];
$parts = OAuthUtil::urlencode_rfc3986($parts);
return implode("&", $parts);
}
/**
* just uppercases the http method
*/
public function get_normalized_http_method()
{
return strtoupper($this->http_method);
}
/**
* parses the url and rebuilds it to be
* scheme://host/path
*/
public function get_normalized_http_url()
{
$parts = parse_url($this->http_url);
$scheme = isset($parts["scheme"]) ? $parts["scheme"] : "http";
$port = isset($parts["port"])
? $parts["port"]
: ($scheme == "https"
? "443"
: "80");
$host = isset($parts["host"]) ? strtolower($parts["host"]) : "";
$path = isset($parts["path"]) ? $parts["path"] : "";
if (
($scheme == "https" && $port != "443") ||
($scheme == "http" && $port != "80")
) {
$host = "$host:$port";
}
return "$scheme://$host$path";
}
/**
* builds a url usable for a GET request
*/
public function to_url()
{
$post_data = $this->to_postdata();
$out = $this->get_normalized_http_url();
if ($post_data) {
$out .= "?" . $post_data;
}
return $out;
}
/**
* builds the data one would send in a POST request
*/
public function to_postdata()
{
return OAuthUtil::build_http_query($this->parameters);
}
/**
* builds the Authorization: header
*/
public function to_header($realm = null)
{
$first = true;
if ($realm) {
$out =
'Authorization: OAuth realm="' .
OAuthUtil::urlencode_rfc3986($realm) .
'"';
$first = false;
} else {
$out = "Authorization: OAuth";
}
$total = [];
foreach ($this->parameters as $k => $v) {
if (substr($k, 0, 5) != "oauth") {
continue;
}
if (is_array($v)) {
throw new OAuthException("Arrays not supported in headers");
}
$out .= $first ? " " : ",";
$out .=
OAuthUtil::urlencode_rfc3986($k) .
'="' .
OAuthUtil::urlencode_rfc3986($v) .
'"';
$first = false;
}
return $out;
}
public function __toString()
{
return $this->to_url();
}
public function sign_request($signature_method, $consumer, $token)
{
$this->set_parameter(
"oauth_signature_method",
$signature_method->get_name(),
false
);
$signature = $this->build_signature(
$signature_method,
$consumer,
$token
);
$this->set_parameter("oauth_signature", $signature, false);
}
public function build_signature($signature_method, $consumer, $token)
{
$signature = $signature_method->build_signature(
$this,
$consumer,
$token
);
return $signature;
}
/**
* util function: current timestamp
*/
private static function generate_timestamp()
{
return time();
}
/**
* util function: current nonce
*/
private static function generate_nonce()
{
$mt = microtime();
$rand = mt_rand();
return md5($mt . $rand); // md5s look nicer than numbers
}
}
class OAuthServer
{
protected $timestamp_threshold = 300; // in seconds, five minutes
protected $version = "1.0"; // hi blaine
protected $signature_methods = [];
protected $data_store;
function __construct($data_store)
{
$this->data_store = $data_store;
}
public function add_signature_method($signature_method)
{
$this->signature_methods[
$signature_method->get_name()
] = $signature_method;
}
// high level functions
/**
* process a request_token request
* returns the request token on success
*/
public function fetch_request_token(&$request)
{
$this->get_version($request);
$consumer = $this->get_consumer($request);
// no token required for the initial token request
$token = null;
$this->check_signature($request, $consumer, $token);
// Rev A change
$callback = $request->get_parameter("oauth_callback");
$new_token = $this->data_store->new_request_token($consumer, $callback);
return $new_token;
}
/**
* process an access_token request
* returns the access token on success
*/
public function fetch_access_token(&$request)
{
$this->get_version($request);
$consumer = $this->get_consumer($request);
// requires authorized request token
$token = $this->get_token($request, $consumer, "request");
$this->check_signature($request, $consumer, $token);
// Rev A change
$verifier = $request->get_parameter("oauth_verifier");
$new_token = $this->data_store->new_access_token(
$token,
$consumer,
$verifier
);
return $new_token;
}
/**
* verify an api call, checks all the parameters
*/
public function verify_request(&$request)
{
$this->get_version($request);
$consumer = $this->get_consumer($request);
$token = $this->get_token($request, $consumer, "access");
$this->check_signature($request, $consumer, $token);
return [$consumer, $token];
}
// Internals from here
/**
* version 1
*/
private function get_version(&$request)
{
$version = $request->get_parameter("oauth_version");
if (!$version) {
// Service Providers MUST assume the protocol version to be 1.0 if this parameter is not present.
// Chapter 7.0 ("Accessing Protected Ressources")
$version = "1.0";
}
if ($version !== $this->version) {
throw new OAuthException("OAuth version '$version' not supported");
}
return $version;
}
/**
* figure out the signature with some defaults
*/
private function get_signature_method($request)
{
$signature_method =
$request instanceof OAuthRequest
? $request->get_parameter("oauth_signature_method")
: null;
if (!$signature_method) {
// According to chapter 7 ("Accessing Protected Ressources") the signature-method
// parameter is required, and we can't just fallback to PLAINTEXT
throw new OAuthException(
"No signature method parameter. This parameter is required"
);
}
if (
!in_array($signature_method, array_keys($this->signature_methods))
) {
throw new OAuthException(
"Signature method '$signature_method' not supported " .
"try one of the following: " .
implode(", ", array_keys($this->signature_methods))
);
}
return $this->signature_methods[$signature_method];
}
/**
* try to find the consumer for the provided request's consumer key
*/
private function get_consumer($request)
{
$consumer_key =
$request instanceof OAuthRequest
? $request->get_parameter("oauth_consumer_key")
: null;
if (!$consumer_key) {
throw new OAuthException("Invalid consumer key");
}
$consumer = $this->data_store->lookup_consumer($consumer_key);
if (!$consumer) {
throw new OAuthException("Invalid consumer");
}
return $consumer;
}
/**
* try to find the token for the provided request's token key
*/
private function get_token($request, $consumer, $token_type = "access")
{
$token_field =
$request instanceof OAuthRequest
? $request->get_parameter("oauth_token")
: null;
$token = $this->data_store->lookup_token(
$consumer,
$token_type,
$token_field
);
if (!$token) {
throw new OAuthException("Invalid $token_type token: $token_field");
}
return $token;
}
/**
* all-in-one function to check the signature on a request
* should guess the signature method appropriately
*/
private function check_signature($request, $consumer, $token)
{
// this should probably be in a different method
$timestamp =
$request instanceof OAuthRequest
? $request->get_parameter("oauth_timestamp")
: null;
$nonce =
$request instanceof OAuthRequest
? $request->get_parameter("oauth_nonce")
: null;
$this->check_timestamp($timestamp);
$this->check_nonce($consumer, $token, $nonce, $timestamp);
$signature_method = $this->get_signature_method($request);
$signature = $request->get_parameter("oauth_signature");
$valid_sig = $signature_method->check_signature(
$request,
$consumer,
$token,
$signature
);
if (!$valid_sig) {
throw new OAuthException("Invalid signature");
}
}
/**
* check that the timestamp is new enough
*/
private function check_timestamp($timestamp)
{
if (!$timestamp) {
throw new OAuthException(
"Missing timestamp parameter. The parameter is required"
);
}
// verify that timestamp is recentish
$now = time();
if (abs($now - $timestamp) > $this->timestamp_threshold) {
throw new OAuthException(
"Expired timestamp, yours $timestamp, ours $now"
);
}
}
/**
* check that the nonce is not repeated
*/
private function check_nonce($consumer, $token, $nonce, $timestamp)
{
if (!$nonce) {
throw new OAuthException(
"Missing nonce parameter. The parameter is required"
);
}
// verify that the nonce is uniqueish
$found = $this->data_store->lookup_nonce(
$consumer,
$token,
$nonce,
$timestamp
);
if ($found) {
throw new OAuthException("Nonce already used: $nonce");
}
}
}
class OAuthDataStore
{
function lookup_consumer($consumer_key)
{
// implement me
}
function lookup_token($consumer, $token_type, $token)
{
// implement me
}
function lookup_nonce($consumer, $token, $nonce, $timestamp)
{
// implement me
}
function new_request_token($consumer, $callback = null)
{
// return a new token attached to this consumer
}
function new_access_token($token, $consumer, $verifier = null)
{
// return a new access token attached to this consumer
// for the user associated with this token if the request token
// is authorized
// should also invalidate the request token
}
}
class OAuthUtil
{
public static function urlencode_rfc3986($input)
{
if (is_array($input)) {
return array_map(["OAuthUtil", "urlencode_rfc3986"], $input);
} elseif (is_scalar($input)) {
return str_replace(
"+",
" ",
str_replace("%7E", "~", rawurlencode($input))
);
} else {
return "";
}
}
// This decode function isn't taking into consideration the above
// modifications to the encoding process. However, this method doesn't
// seem to be used anywhere so leaving it as is.
public static function urldecode_rfc3986($string)
{
return urldecode($string);
}
// Utility function for turning the Authorization: header into
// parameters, has to do some unescaping
// Can filter out any non-oauth parameters if needed (default behaviour)
// May 28th, 2010 - method updated to tjerk.meesters for a speed improvement.
// see http://code.google.com/p/oauth/issues/detail?id=163
public static function split_header(
$header,
$only_allow_oauth_parameters = true
) {
$params = [];
if (
preg_match_all(
"/(" .
($only_allow_oauth_parameters ? "oauth_" : "") .
'[a-z_-]*)=(:?"([^"]*)"|([^,]*))/',
$header,
$matches
)
) {
foreach ($matches[1] as $i => $h) {
$params[$h] = OAuthUtil::urldecode_rfc3986(
empty($matches[3][$i]) ? $matches[4][$i] : $matches[3][$i]
);
}
if (isset($params["realm"])) {
unset($params["realm"]);
}
}
return $params;
}
// helper to try to sort out headers for people who aren't running apache
public static function get_headers()
{
if (function_exists("apache_request_headers")) {
// we need this to get the actual Authorization: header
// because apache tends to tell us it doesn't exist
$headers = apache_request_headers();
// sanitize the output of apache_request_headers because
// we always want the keys to be Cased-Like-This and arh()
// returns the headers in the same case as they are in the
// request
$out = [];
foreach ($headers as $key => $value) {
$key = str_replace(
" ",
"-",
ucwords(strtolower(str_replace("-", " ", $key)))
);
$out[$key] = $value;
}
} else {
// otherwise we don't have apache and are just going to have to hope
// that $_SERVER actually contains what we need
$out = [];
if (isset($_SERVER["CONTENT_TYPE"])) {
$out["Content-Type"] = $_SERVER["CONTENT_TYPE"];
}
if (isset($_ENV["CONTENT_TYPE"])) {
$out["Content-Type"] = $_ENV["CONTENT_TYPE"];
}
foreach ($_SERVER as $key => $value) {
if (substr($key, 0, 5) == "HTTP_") {
// this is chaos, basically it is just there to capitalize the first
// letter of every word that is not an initial HTTP and strip HTTP
// code from przemek
$key = str_replace(
" ",
"-",
ucwords(
strtolower(str_replace("_", " ", substr($key, 5)))
)
);
$out[$key] = $value;
}
}
}
return $out;
}
// This function takes a input like a=b&a=c&d=e and returns the parsed
// parameters like this
// array('a' => array('b','c'), 'd' => 'e')
public static function parse_parameters($input)
{
if (!isset($input) || !$input) {
return [];
}
$pairs = explode("&", $input);
$parsed_parameters = [];
foreach ($pairs as $pair) {
$split = explode("=", $pair, 2);
$parameter = OAuthUtil::urldecode_rfc3986($split[0]);
$value = isset($split[1])
? OAuthUtil::urldecode_rfc3986($split[1])
: "";
if (isset($parsed_parameters[$parameter])) {
// We have already recieved parameter(s) with this name, so add to the list
// of parameters with this name
if (is_scalar($parsed_parameters[$parameter])) {
// This is the first duplicate, so transform scalar (string) into an array
// so we can add the duplicates
$parsed_parameters[$parameter] = [
$parsed_parameters[$parameter],
];
}
$parsed_parameters[$parameter][] = $value;
} else {
$parsed_parameters[$parameter] = $value;
}
}
return $parsed_parameters;
}
public static function build_http_query($params)
{
if (!$params) {
return "";
}
// Urlencode both keys and values
$keys = OAuthUtil::urlencode_rfc3986(array_keys($params));
$values = OAuthUtil::urlencode_rfc3986(array_values($params));
$params = array_combine($keys, $values);
// Parameters are sorted by name, using lexicographical byte value ordering.
// Ref: Spec: 9.1.1 (1)
uksort($params, "strcmp");
$pairs = [];
foreach ($params as $parameter => $value) {
if (is_array($value)) {
// If two or more parameters share the same name, they are sorted by their value
// Ref: Spec: 9.1.1 (1)
// June 12th, 2010 - changed to sort because of issue 164 by hidetaka
sort($value, SORT_STRING);
foreach ($value as $duplicate_value) {
$pairs[] = $parameter . "=" . $duplicate_value;
}
} else {
$pairs[] = $parameter . "=" . $value;
}
}
// For each parameter, the name is separated from the corresponding value by an '=' character (ASCII code 61)
// Each name-value pair is separated by an '&' character (ASCII code 38)
return implode("&", $pairs);
}
}
?>