* Facebook support

1 files changed, 332 insertions, 0 deletions

diff --git a/lib/facebook-graph-sdk/src/Facebook/SignedRequest.php b/lib/facebook-graph-sdk/src/Facebook/SignedRequest.php
new file mode 100644
index 0000000..77099a3
--- /dev/null
+++ b/lib/facebook-graph-sdk/src/Facebook/SignedRequest.php
@@ -0,0 +1,332 @@
+<?php
+/**
+ * Copyright 2014 Facebook, Inc.
+ *
+ * You are hereby granted a non-exclusive, worldwide, royalty-free license to
+ * use, copy, modify, and distribute this software in source code or binary
+ * form for use in connection with the web services and APIs provided by
+ * Facebook.
+ *
+ * As with any software that integrates with the Facebook platform, your use
+ * of this software is subject to the Facebook Developer Principles and
+ * Policies [http://developers.facebook.com/policy/]. This copyright notice
+ * shall be included in all copies or substantial portions of the software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ */
+namespace Facebook;
+
+use Facebook\Exceptions\FacebookSDKException;
+
+/**
+ * Class SignedRequest
+ *
+ * @package Facebook
+ */
+class SignedRequest
+{
+    /**
+     * @var FacebookApp The FacebookApp entity.
+     */
+    protected $app;
+
+    /**
+     * @var string The raw encrypted signed request.
+     */
+    protected $rawSignedRequest;
+
+    /**
+     * @var array The payload from the decrypted signed request.
+     */
+    protected $payload;
+
+    /**
+     * Instantiate a new SignedRequest entity.
+     *
+     * @param FacebookApp $facebookApp      The FacebookApp entity.
+     * @param string|null $rawSignedRequest The raw signed request.
+     */
+    public function __construct(FacebookApp $facebookApp, $rawSignedRequest = null)
+    {
+        $this->app = $facebookApp;
+
+        if (!$rawSignedRequest) {
+            return;
+        }
+
+        $this->rawSignedRequest = $rawSignedRequest;
+
+        $this->parse();
+    }
+
+    /**
+     * Returns the raw signed request data.
+     *
+     * @return string|null
+     */
+    public function getRawSignedRequest()
+    {
+        return $this->rawSignedRequest;
+    }
+
+    /**
+     * Returns the parsed signed request data.
+     *
+     * @return array|null
+     */
+    public function getPayload()
+    {
+        return $this->payload;
+    }
+
+    /**
+     * Returns a property from the signed request data if available.
+     *
+     * @param string     $key
+     * @param mixed|null $default
+     *
+     * @return mixed|null
+     */
+    public function get($key, $default = null)
+    {
+        if (isset($this->payload[$key])) {
+            return $this->payload[$key];
+        }
+
+        return $default;
+    }
+
+    /**
+     * Returns user_id from signed request data if available.
+     *
+     * @return string|null
+     */
+    public function getUserId()
+    {
+        return $this->get('user_id');
+    }
+
+    /**
+     * Checks for OAuth data in the payload.
+     *
+     * @return boolean
+     */
+    public function hasOAuthData()
+    {
+        return $this->get('oauth_token') || $this->get('code');
+    }
+
+    /**
+     * Creates a signed request from an array of data.
+     *
+     * @param array $payload
+     *
+     * @return string
+     */
+    public function make(array $payload)
+    {
+        $payload['algorithm'] = isset($payload['algorithm']) ? $payload['algorithm'] : 'HMAC-SHA256';
+        $payload['issued_at'] = isset($payload['issued_at']) ? $payload['issued_at'] : time();
+        $encodedPayload = $this->base64UrlEncode(json_encode($payload));
+
+        $hashedSig = $this->hashSignature($encodedPayload);
+        $encodedSig = $this->base64UrlEncode($hashedSig);
+
+        return $encodedSig . '.' . $encodedPayload;
+    }
+
+    /**
+     * Validates and decodes a signed request and saves
+     * the payload to an array.
+     */
+    protected function parse()
+    {
+        list($encodedSig, $encodedPayload) = $this->split();
+
+        // Signature validation
+        $sig = $this->decodeSignature($encodedSig);
+        $hashedSig = $this->hashSignature($encodedPayload);
+        $this->validateSignature($hashedSig, $sig);
+
+        $this->payload = $this->decodePayload($encodedPayload);
+
+        // Payload validation
+        $this->validateAlgorithm();
+    }
+
+    /**
+     * Splits a raw signed request into signature and payload.
+     *
+     * @returns array
+     *
+     * @throws FacebookSDKException
+     */
+    protected function split()
+    {
+        if (strpos($this->rawSignedRequest, '.') === false) {
+            throw new FacebookSDKException('Malformed signed request.', 606);
+        }
+
+        return explode('.', $this->rawSignedRequest, 2);
+    }
+
+    /**
+     * Decodes the raw signature from a signed request.
+     *
+     * @param string $encodedSig
+     *
+     * @returns string
+     *
+     * @throws FacebookSDKException
+     */
+    protected function decodeSignature($encodedSig)
+    {
+        $sig = $this->base64UrlDecode($encodedSig);
+
+        if (!$sig) {
+            throw new FacebookSDKException('Signed request has malformed encoded signature data.', 607);
+        }
+
+        return $sig;
+    }
+
+    /**
+     * Decodes the raw payload from a signed request.
+     *
+     * @param string $encodedPayload
+     *
+     * @returns array
+     *
+     * @throws FacebookSDKException
+     */
+    protected function decodePayload($encodedPayload)
+    {
+        $payload = $this->base64UrlDecode($encodedPayload);
+
+        if ($payload) {
+            $payload = json_decode($payload, true);
+        }
+
+        if (!is_array($payload)) {
+            throw new FacebookSDKException('Signed request has malformed encoded payload data.', 607);
+        }
+
+        return $payload;
+    }
+
+    /**
+     * Validates the algorithm used in a signed request.
+     *
+     * @throws FacebookSDKException
+     */
+    protected function validateAlgorithm()
+    {
+        if ($this->get('algorithm') !== 'HMAC-SHA256') {
+            throw new FacebookSDKException('Signed request is using the wrong algorithm.', 605);
+        }
+    }
+
+    /**
+     * Hashes the signature used in a signed request.
+     *
+     * @param string $encodedData
+     *
+     * @return string
+     *
+     * @throws FacebookSDKException
+     */
+    protected function hashSignature($encodedData)
+    {
+        $hashedSig = hash_hmac(
+            'sha256',
+            $encodedData,
+            $this->app->getSecret(),
+            $raw_output = true
+        );
+
+        if (!$hashedSig) {
+            throw new FacebookSDKException('Unable to hash signature from encoded payload data.', 602);
+        }
+
+        return $hashedSig;
+    }
+
+    /**
+     * Validates the signature used in a signed request.
+     *
+     * @param string $hashedSig
+     * @param string $sig
+     *
+     * @throws FacebookSDKException
+     */
+    protected function validateSignature($hashedSig, $sig)
+    {
+        if (mb_strlen($hashedSig) === mb_strlen($sig)) {
+            $validate = 0;
+            for ($i = 0; $i < mb_strlen($sig); $i++) {
+                $validate |= ord($hashedSig[$i]) ^ ord($sig[$i]);
+            }
+            if ($validate === 0) {
+                return;
+            }
+        }
+
+        throw new FacebookSDKException('Signed request has an invalid signature.', 602);
+    }
+
+    /**
+     * Base64 decoding which replaces characters:
+     *   + instead of -
+     *   / instead of _
+     *
+     * @link http://en.wikipedia.org/wiki/Base64#URL_applications
+     *
+     * @param string $input base64 url encoded input
+     *
+     * @return string decoded string
+     */
+    public function base64UrlDecode($input)
+    {
+        $urlDecodedBase64 = strtr($input, '-_', '+/');
+        $this->validateBase64($urlDecodedBase64);
+
+        return base64_decode($urlDecodedBase64);
+    }
+
+    /**
+     * Base64 encoding which replaces characters:
+     *   + instead of -
+     *   / instead of _
+     *
+     * @link http://en.wikipedia.org/wiki/Base64#URL_applications
+     *
+     * @param string $input string to encode
+     *
+     * @return string base64 url encoded input
+     */
+    public function base64UrlEncode($input)
+    {
+        return strtr(base64_encode($input), '+/', '-_');
+    }
+
+    /**
+     * Validates a base64 string.
+     *
+     * @param string $input base64 value to validate
+     *
+     * @throws FacebookSDKException
+     */
+    protected function validateBase64($input)
+    {
+        if (!preg_match('/^[a-zA-Z0-9\/\r\n+]*={0,2}$/', $input)) {
+            throw new FacebookSDKException('Signed request contains malformed base64 encoding.', 608);
+        }
+    }
+}