3 * StatusNet - the distributed open-source microblogging tool
4 * Copyright (C) 2010, StatusNet, Inc.
6 * A sample module to show best practices for StatusNet plugins
10 * This program is free software: you can redistribute it and/or modify
11 * it under the terms of the GNU Affero General Public License as published by
12 * the Free Software Foundation, either version 3 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU Affero General Public License for more details.
20 * You should have received a copy of the GNU Affero General Public License
21 * along with this program. If not, see <http://www.gnu.org/licenses/>.
24 * @author James Walker <james@status.net>
25 * @copyright 2010 StatusNet, Inc.
26 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
27 * @link http://status.net/
31 const ENCODING = 'base64url';
33 const NS = 'http://salmon-protocol.org/ns/magic-env';
35 protected $data = null; // When stored here it is _always_ base64url encoded
36 protected $data_type = null;
37 protected $encoding = null;
38 protected $alg = null;
39 protected $sig = null;
42 * Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
44 * @param string XML source
45 * @return mixed associative array of envelope data, or false on unrecognized input
47 * @fixme will spew errors to logs or output in case of XML parse errors
48 * @fixme may give fatal errors if some elements are missing or invalid XML
49 * @fixme calling DOMDocument::loadXML statically triggers warnings in strict mode
51 public function __construct($xml=null) {
53 $dom = DOMDocument::loadXML($xml);
54 if (!$dom instanceof DOMDocument) {
55 throw new ServerException('Tried to load malformed XML as DOM');
56 } elseif (!$this->fromDom($dom)) {
57 throw new ServerException('Could not load MagicEnvelope from DOM');
63 * Retrieve Salmon keypair first by checking local database, but
64 * if it's not found, attempt discovery if it has been requested.
66 * @param Profile $profile The profile we're looking up keys for.
67 * @param boolean $discovery Network discovery if no local cache?
69 public function getKeyPair(Profile $profile, $discovery=false) {
70 $magicsig = Magicsig::getKV('user_id', $profile->id);
72 if ($discovery && !$magicsig instanceof Magicsig) {
73 // Throws exception on failure, but does not try to _load_ the keypair string.
74 $keypair = $this->discoverKeyPair($profile);
76 $magicsig = new Magicsig();
77 $magicsig->user_id = $profile->id;
78 $magicsig->importKeys($keypair);
79 } elseif (!$magicsig instanceof Magicsig) { // No discovery request, so we'll give up.
80 throw new ServerException(sprintf('No public key found for profile (id==%d)', $profile->id));
83 assert($magicsig->publicKey instanceof Crypt_RSA);
89 * Get the Salmon keypair from a URI, uses XRD Discovery etc. Reasonably
90 * you'll only get the public key ;)
92 * The string will (hopefully) be formatted as described in Magicsig specification:
93 * https://salmon-protocol.googlecode.com/svn/trunk/draft-panzer-magicsig-01.html#anchor13
95 * @return string formatted as Magicsig keypair
97 public function discoverKeyPair(Profile $profile)
99 $signer_uri = $profile->getUri();
100 if (empty($signer_uri)) {
101 throw new ServerException(sprintf('Profile missing URI (id==%d)', $profile->id));
104 $disco = new Discovery();
106 // Throws exception on lookup problems
107 $xrd = $disco->lookup($signer_uri);
109 $link = $xrd->get(Magicsig::PUBLICKEYREL);
110 if (is_null($link)) {
112 throw new Exception(_m('Unable to locate signer public key.'));
115 // We have a public key element, let's hope it has proper key data.
117 $parts = explode(',', $link->href);
118 if (count($parts) == 2) {
119 $keypair = $parts[1];
121 // Backwards compatibility check for separator bug in 0.9.0
122 $parts = explode(';', $link->href);
123 if (count($parts) == 2) {
124 $keypair = $parts[1];
128 if ($keypair === false) {
129 // For debugging clarity. Keypair did not pass count()-check above.
130 // TRANS: Exception when public key was not properly formatted.
131 throw new Exception(_m('Incorrectly formatted public key element.'));
138 * The current MagicEnvelope spec as used in StatusNet 0.9.7 and later
139 * includes both the original data and some signing metadata fields as
140 * the input plaintext for the signature hash.
144 public function signingText() {
145 return implode('.', array($this->data, // this field is pre-base64'd
146 Magicsig::base64_url_encode($this->data_type),
147 Magicsig::base64_url_encode($this->encoding),
148 Magicsig::base64_url_encode($this->alg)));
153 * @param <type> $text
154 * @param <type> $mimetype
155 * @param Magicsig $magicsig Magicsig with private key available.
157 * @return MagicEnvelope object with all properties set
159 * @throws Exception of various kinds on signing failure
161 public function signMessage($text, $mimetype, Magicsig $magicsig)
163 assert($magicsig->privateKey instanceof Crypt_RSA);
165 // Prepare text and metadata for signing
166 $this->data = Magicsig::base64_url_encode($text);
167 $this->data_type = $mimetype;
168 $this->encoding = self::ENCODING;
169 $this->alg = $magicsig->getName();
171 // Get the actual signature
172 $this->sig = $magicsig->sign($this->signingText());
176 * Create an <me:env> XML representation of the envelope.
178 * @return string representation of XML document
180 public function toXML() {
181 $xs = new XMLStringer();
183 $xs->elementStart('me:env', array('xmlns:me' => self::NS));
184 $xs->element('me:data', array('type' => $this->data_type), $this->data);
185 $xs->element('me:encoding', null, $this->encoding);
186 $xs->element('me:alg', null, $this->alg);
187 $xs->element('me:sig', null, $this->getSignature());
188 $xs->elementEnd('me:env');
190 $string = $xs->getString();
191 common_debug('MagicEnvelope XML: ' . $string);
196 * Extract the contained XML payload, and insert a copy of the envelope
197 * signature data as an <me:provenance> section.
199 * @return DOMDocument of Atom entry
201 * @fixme in case of XML parsing errors, this will spew to the error log or output
203 public function getPayload()
205 $dom = new DOMDocument();
206 if (!$dom->loadXML(Magicsig::base64_url_decode($this->data))) {
207 throw new ServerException('Malformed XML in Salmon payload');
210 switch ($this->data_type) {
211 case 'application/atom+xml':
212 if ($dom->documentElement->namespaceURI !== Activity::ATOM
213 || $dom->documentElement->tagName !== 'entry') {
214 throw new ServerException(_m('Salmon post must be an Atom entry.'));
216 $prov = $dom->createElementNS(self::NS, 'me:provenance');
217 $prov->setAttribute('xmlns:me', self::NS);
218 $data = $dom->createElementNS(self::NS, 'me:data', $this->data);
219 $data->setAttribute('type', $this->data_type);
220 $prov->appendChild($data);
221 $enc = $dom->createElementNS(self::NS, 'me:encoding', $this->encoding);
222 $prov->appendChild($enc);
223 $alg = $dom->createElementNS(self::NS, 'me:alg', $this->alg);
224 $prov->appendChild($alg);
225 $sig = $dom->createElementNS(self::NS, 'me:sig', $this->getSignature());
226 $prov->appendChild($sig);
228 $dom->documentElement->appendChild($prov);
231 throw new ServerException('Unknown Salmon payload data type');
236 public function getSignature()
242 * Find the author URI referenced in the payload Atom entry.
244 * @return string URI for author
245 * @throws ServerException on failure
247 public function getAuthorUri() {
248 $doc = $this->getPayload();
250 $authors = $doc->documentElement->getElementsByTagName('author');
251 foreach ($authors as $author) {
252 $uris = $author->getElementsByTagName('uri');
253 foreach ($uris as $uri) {
254 return $uri->nodeValue;
257 throw new ServerException('No author URI found in Salmon payload data');
261 * Attempt to verify cryptographic signing for parsed envelope data.
262 * Requires network access to retrieve public key referenced by the envelope signer.
264 * Details of failure conditions are dumped to output log and not exposed to caller.
266 * @param Profile $profile profile used to get locally cached public signature key
267 * or if necessary perform discovery on.
271 public function verify(Profile $profile)
273 if ($this->alg != 'RSA-SHA256') {
274 common_log(LOG_DEBUG, "Salmon error: bad algorithm");
278 if ($this->encoding != self::ENCODING) {
279 common_log(LOG_DEBUG, "Salmon error: bad encoding");
284 $magicsig = $this->getKeyPair($profile, true); // Do discovery too if necessary
285 } catch (Exception $e) {
286 common_log(LOG_DEBUG, "Salmon error: ".$e->getMessage());
290 return $magicsig->verify($this->signingText(), $this->getSignature());
294 * Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
296 * @param DOMDocument $dom
297 * @return mixed associative array of envelope data, or false on unrecognized input
299 * @fixme may give fatal errors if some elements are missing
301 protected function fromDom(DOMDocument $dom)
303 $env_element = $dom->getElementsByTagNameNS(self::NS, 'env')->item(0);
305 $env_element = $dom->getElementsByTagNameNS(self::NS, 'provenance')->item(0);
312 $data_element = $env_element->getElementsByTagNameNS(self::NS, 'data')->item(0);
313 $sig_element = $env_element->getElementsByTagNameNS(self::NS, 'sig')->item(0);
315 $this->data = preg_replace('/\s/', '', $data_element->nodeValue);
316 $this->data_type = $data_element->getAttribute('type');
317 $this->encoding = $env_element->getElementsByTagNameNS(self::NS, 'encoding')->item(0)->nodeValue;
318 $this->alg = $env_element->getElementsByTagNameNS(self::NS, 'alg')->item(0)->nodeValue;
319 $this->sig = preg_replace('/\s/', '', $sig_element->nodeValue);
324 * Encode the given string as a signed MagicEnvelope XML document,
325 * using the keypair for the given local user profile. We can of
326 * course not sign a remote profile's slap, since we don't have the
329 * Side effects: will create and store a keypair on-demand if one
330 * hasn't already been generated for this user. This can be very slow
333 * @param string $text XML fragment to sign, assumed to be Atom
334 * @param User $user User who cryptographically signs $text
336 * @return MagicEnvelope object complete with signature
338 * @throws Exception on bad profile input or key generation problems
340 public static function signAsUser($text, User $user)
342 // Find already stored key
343 $magicsig = Magicsig::getKV('user_id', $user->id);
344 if (!$magicsig instanceof Magicsig) {
345 $magicsig = Magicsig::generate($user);
347 assert($magicsig instanceof Magicsig);
348 assert($magicsig->privateKey instanceof Crypt_RSA);
350 $magic_env = new MagicEnvelope();
351 $magic_env->signMessage($text, 'application/atom+xml', $magicsig);