Google_OAuth2.php from Google Analyticator v.6.4.3 with modifications to fix "Fatal error: Uncaught exception 'Google_AuthException'" See revision history for details on what I changed to fix the error. See this wordpress.org support forum posting about the issue: http://wordpress.org/support/topic/solution-for-fatal-error-uncaught-exception-goo…

Google_OAuth2.php

<?php
/*
 * Copyright 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

require_once "Google_Verifier.php";
require_once "Google_LoginTicket.php";
require_once "service/Google_Utils.php";

/**
 * Authentication class that deals with the OAuth 2 web-server authentication flow
 *
 * @author Chris Chabot <chabotc@google.com>
 * @author Chirag Shah <chirags@google.com>
 *
 */
class Google_OAuth2 extends Google_Auth {
  public $clientId;
  public $clientSecret;
  public $developerKey;
  public $token;
  public $redirectUri;
  public $state;
  public $accessType = 'offline';
  public $approvalPrompt = 'force';

  /** @var Google_AssertionCredentials $assertionCredentials */
  public $assertionCredentials;

  const OAUTH2_REVOKE_URI = 'https://accounts.google.com/o/oauth2/revoke';
  const OAUTH2_TOKEN_URI = 'https://accounts.google.com/o/oauth2/token';
  const OAUTH2_AUTH_URL = 'https://accounts.google.com/o/oauth2/auth';
  const OAUTH2_FEDERATED_SIGNON_CERTS_URL = 'https://www.googleapis.com/oauth2/v1/certs';
  const CLOCK_SKEW_SECS = 300; // five minutes in seconds
  const AUTH_TOKEN_LIFETIME_SECS = 300; // five minutes in seconds
  const MAX_TOKEN_LIFETIME_SECS = 86400; // one day in seconds

  /**
   * Instantiates the class, but does not initiate the login flow, leaving it
   * to the discretion of the caller (which is done by calling authenticate()).
   */
  public function __construct() {
    global $apiConfig;
    
    if (! empty($apiConfig['developer_key'])) {
      $this->developerKey = $apiConfig['developer_key'];
    }

    if (! empty($apiConfig['oauth2_client_id'])) {
      $this->clientId = $apiConfig['oauth2_client_id'];
    }

    if (! empty($apiConfig['oauth2_client_secret'])) {
      $this->clientSecret = $apiConfig['oauth2_client_secret'];
    }

    if (! empty($apiConfig['oauth2_redirect_uri'])) {
      $this->redirectUri = $apiConfig['oauth2_redirect_uri'];
    }
    
    if (! empty($apiConfig['oauth2_access_type'])) {
      $this->accessType = $apiConfig['oauth2_access_type'];
    }

    if (! empty($apiConfig['oauth2_approval_prompt'])) {
      $this->approvalPrompt = $apiConfig['oauth2_approval_prompt'];
    }
  }

  /**
   * @param $service
   * @param string|null $code
   * @throws Google_AuthException
   * @return string
   */
  public function authenticate($service, $code = null) {
    if (!$code && isset($_GET['code'])) {
      $code = $_GET['code'];
    }

    if ($code) {
      // We got here from the redirect from a successful authorization grant, fetch the access token
      $request = Google_Client::$io->makeRequest(new Google_HttpRequest(self::OAUTH2_TOKEN_URI, 'POST', array(), array(
          'code' => $code,
          'grant_type' => 'authorization_code',
          'redirect_uri' => $this->redirectUri,
          'client_id' => $this->clientId,
          'client_secret' => $this->clientSecret
      )));

      if ($request->getResponseHttpCode() == 200) {
        $this->setAccessToken($request->getResponseBody());
        $this->token['created'] = time();
        return $this->getAccessToken();
      } else {
        $response = $request->getResponseBody();
        $decodedResponse = json_decode($response, true);
        if ($decodedResponse != null && $decodedResponse['error']) {
          $response = $decodedResponse['error'];
        }
        throw new Google_AuthException("Error fetching OAuth2 access token, message: '$response'", $request->getResponseHttpCode());
      }
    }

    $authUrl = $this->createAuthUrl($service['scope']);
    header('Location: ' . $authUrl);
    return true;
  } 

  /**
   * Create a URL to obtain user authorization.
   * The authorization endpoint allows the user to first
   * authenticate, and then grant/deny the access request.
   * @param string $scope The scope is expressed as a list of space-delimited strings.
   * @return string
   */
  public function createAuthUrl($scope) {
    $params = array(
        'response_type=code',
        'redirect_uri=' . urlencode($this->redirectUri),
        'client_id=' . urlencode($this->clientId),
        'scope=' . urlencode($scope),
        'access_type=' . urlencode($this->accessType),
        'approval_prompt=' . urlencode($this->approvalPrompt)
    );

    if (isset($this->state)) {
      $params[] = 'state=' . urlencode($this->state);
    }
    $params = implode('&', $params);
    return self::OAUTH2_AUTH_URL . "?$params";
  }

  /**
   * @param string $token
   * @throws Google_AuthException
   */
  public function setAccessToken($token) {
    $token = json_decode($token, true);
    if ($token == null) {
      throw new Google_AuthException('Could not json decode the token');
    }
    if (! isset($token['access_token'])) {
      throw new Google_AuthException("Invalid token format");
    }
    $this->token = $token;
  }

  public function getAccessToken() {
    return json_encode($this->token);
  }

  public function setDeveloperKey($developerKey) {
    $this->developerKey = $developerKey;
  }

  public function setState($state) {
    $this->state = $state;
  }

  public function setAccessType($accessType) {
    $this->accessType = $accessType;
  }

  public function setApprovalPrompt($approvalPrompt) {
    $this->approvalPrompt = $approvalPrompt;
  }

  public function setAssertionCredentials(Google_AssertionCredentials $creds) {
    $this->assertionCredentials = $creds;
  }

  /**
   * Include an accessToken in a given apiHttpRequest.
   * @param Google_HttpRequest $request
   * @return Google_HttpRequest
   * @throws Google_AuthException
   */
  public function sign(Google_HttpRequest $request) {
    // add the developer key to the request before signing it
    if ($this->developerKey) {
      $requestUrl = $request->getUrl();
      $requestUrl .= (strpos($request->getUrl(), '?') === false) ? '?' : '&';
      $requestUrl .=  'key=' . urlencode($this->developerKey);
      $request->setUrl($requestUrl);
    }

    // Cannot sign the request without an OAuth access token.
    if (null == $this->token && null == $this->assertionCredentials) {
      return $request;
    }

    // Check if the token is set to expire in the next 30 seconds
    // (or has already expired).
    if ($this->isAccessTokenExpired()) {
      if ($this->assertionCredentials) {
        $this->refreshTokenWithAssertion();
      } else {
        if (! array_key_exists('refresh_token', $this->token)) {
            throw new Google_AuthException("The OAuth 2.0 access token has expired, "
                . "and a refresh token is not available. Refresh tokens are not "
                . "returned for responses that were auto-approved.");
        }
        $this->refreshToken($this->token['refresh_token']);
      }
    }

    // Add the OAuth2 header to the request
    $request->setRequestHeaders(
        array('Authorization' => 'Bearer ' . $this->token['access_token'])
    );

    return $request;
  }

  /**
   * Fetches a fresh access token with the given refresh token.
   * @param string $refreshToken
   * @return void
   */
  public function refreshToken($refreshToken) {
    try {
      $this->refreshTokenRequest(array(
		   'client_id' => $this->clientId,
		   'client_secret' => $this->clientSecret,
		   'refresh_token' => $refreshToken,
		   'grant_type' => 'refresh_token'
	    ));
	  }	catch (Google_AuthException $e) {
		echo 'AUTHORIZATION ERROR - RESET ALL GOOGLE AUTORIZATION. Error message: <div>',  $e->getMessage(), "</div>\n";
	}
  }

  /**
   * Fetches a fresh access token with a given assertion token.
   * @param Google_AssertionCredentials $assertionCredentials optional.
   * @return void
   */
  public function refreshTokenWithAssertion($assertionCredentials = null) {
    if (!$assertionCredentials) {
      $assertionCredentials = $this->assertionCredentials;
    }

    $this->refreshTokenRequest(array(
        'grant_type' => 'assertion',
        'assertion_type' => $assertionCredentials->assertionType,
        'assertion' => $assertionCredentials->generateAssertion(),
    ));
  }

  private function refreshTokenRequest($params) {
    $http = new Google_HttpRequest(self::OAUTH2_TOKEN_URI, 'POST', array(), $params);
    $request = Google_Client::$io->makeRequest($http);

    $code = $request->getResponseHttpCode();
    $body = $request->getResponseBody();
    if (200 == $code) {
      $token = json_decode($body, true);
      if ($token == null) {
        throw new Google_AuthException("Could not json decode the access token");
      }

      if (! isset($token['access_token']) || ! isset($token['expires_in'])) {
        throw new Google_AuthException("Invalid token format");
      }

      $this->token['access_token'] = $token['access_token'];
      $this->token['expires_in'] = $token['expires_in'];
      $this->token['created'] = time();
    } else {
      throw new Google_AuthException("Error refreshing the OAuth2 token, message: '$body'", $code);
    }
  }

    /**
     * Revoke an OAuth2 access token or refresh token. This method will revoke the current access
     * token, if a token isn't provided.
     * @throws Google_AuthException
     * @param string|null $token The token (access token or a refresh token) that should be revoked.
     * @return boolean Returns True if the revocation was successful, otherwise False.
     */
  public function revokeToken($token = null) {
    if (!$token) {
      $token = $this->token['access_token'];
    }
    $request = new Google_HttpRequest(self::OAUTH2_REVOKE_URI, 'POST', array(), "token=$token");
    $response = Google_Client::$io->makeRequest($request);
    $code = $response->getResponseHttpCode();
    if ($code == 200) {
      $this->token = null;
      return true;
    }

    return false;
  }

  /**
   * Returns if the access_token is expired.
   * @return bool Returns True if the access_token is expired.
   */
  public function isAccessTokenExpired() {
    if (null == $this->token) {
      return true;
    }

    // If the token is set to expire in the next 30 seconds.
    $expired = ($this->token['created']
        + ($this->token['expires_in'] - 30)) < time();

    return $expired;
  }

  // Gets federated sign-on certificates to use for verifying identity tokens.
  // Returns certs as array structure, where keys are key ids, and values
  // are PEM encoded certificates.
  private function getFederatedSignOnCerts() {
    // This relies on makeRequest caching certificate responses.
    $request = Google_Client::$io->makeRequest(new Google_HttpRequest(
        self::OAUTH2_FEDERATED_SIGNON_CERTS_URL));
    if ($request->getResponseHttpCode() == 200) {
      $certs = json_decode($request->getResponseBody(), true);
      if ($certs) {
        return $certs;
      }
    }
    throw new Google_AuthException(
        "Failed to retrieve verification certificates: '" .
            $request->getResponseBody() . "'.",
        $request->getResponseHttpCode());
  }

  /**
   * Verifies an id token and returns the authenticated apiLoginTicket.
   * Throws an exception if the id token is not valid.
   * The audience parameter can be used to control which id tokens are
   * accepted.  By default, the id token must have been issued to this OAuth2 client.
   *
   * @param $id_token
   * @param $audience
   * @return Google_LoginTicket
   */
  public function verifyIdToken($id_token = null, $audience = null) {
    if (!$id_token) {
      $id_token = $this->token['id_token'];
    }

    $certs = $this->getFederatedSignonCerts();
    if (!$audience) {
      $audience = $this->clientId;
    }
    return $this->verifySignedJwtWithCerts($id_token, $certs, $audience);
  }

  // Verifies the id token, returns the verified token contents.
  // Visible for testing.
  function verifySignedJwtWithCerts($jwt, $certs, $required_audience) {
    $segments = explode(".", $jwt);
    if (count($segments) != 3) {
      throw new Google_AuthException("Wrong number of segments in token: $jwt");
    }
    $signed = $segments[0] . "." . $segments[1];
    $signature = Google_Utils::urlSafeB64Decode($segments[2]);

    // Parse envelope.
    $envelope = json_decode(Google_Utils::urlSafeB64Decode($segments[0]), true);
    if (!$envelope) {
      throw new Google_AuthException("Can't parse token envelope: " . $segments[0]);
    }

    // Parse token
    $json_body = Google_Utils::urlSafeB64Decode($segments[1]);
    $payload = json_decode($json_body, true);
    if (!$payload) {
      throw new Google_AuthException("Can't parse token payload: " . $segments[1]);
    }

    // Check signature
    $verified = false;
    foreach ($certs as $keyName => $pem) {
      $public_key = new Google_PemVerifier($pem);
      if ($public_key->verify($signed, $signature)) {
        $verified = true;
        break;
      }
    }

    if (!$verified) {
      throw new Google_AuthException("Invalid token signature: $jwt");
    }

    // Check issued-at timestamp
    $iat = 0;
    if (array_key_exists("iat", $payload)) {
      $iat = $payload["iat"];
    }
    if (!$iat) {
      throw new Google_AuthException("No issue time in token: $json_body");
    }
    $earliest = $iat - self::CLOCK_SKEW_SECS;

    // Check expiration timestamp
    $now = time();
    $exp = 0;
    if (array_key_exists("exp", $payload)) {
      $exp = $payload["exp"];
    }
    if (!$exp) {
      throw new Google_AuthException("No expiration time in token: $json_body");
    }
    if ($exp >= $now + self::MAX_TOKEN_LIFETIME_SECS) {
      throw new Google_AuthException(
          "Expiration time too far in future: $json_body");
    }

    $latest = $exp + self::CLOCK_SKEW_SECS;
    if ($now < $earliest) {
      throw new Google_AuthException(
          "Token used too early, $now < $earliest: $json_body");
    }
    if ($now > $latest) {
      throw new Google_AuthException(
          "Token used too late, $now > $latest: $json_body");
    }

    // TODO(beaton): check issuer field?

    // Check audience
    $aud = $payload["aud"];
    if ($aud != $required_audience) {
      throw new Google_AuthException("Wrong recipient, $aud != $required_audience: $json_body");
    }

    // All good.
    return new Google_LoginTicket($envelope, $payload);
  }
}

By the way, regarding:

As far as I can tell the Google_Oauth2.php file is not one you wrote, but rather an API file from Google. Either way the bug is in that file.

It's not a bug, it's a feature. In object-oriented programming, throwing exceptions is the preferred way to communicate error conditions. It's your code's (or VMU's code in that instance) responsibility to catch exceptions from objects it uses. Which is what I'm proposing as a fix, here:

http://wordpress.org/support/topic/solution-for-fatal-error-uncaught-exception-google_authexception-1?replies=0