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', $profile->id);
71 if ($discovery && !$magicsig instanceof Magicsig) {
72 $signer_uri = $profile->getUri();
73 if (empty($signer_uri)) {
74 throw new ServerException(sprintf('Profile missing URI (id==%d)', $profile->id));
76 $magicsig = $this->discoverKeyPair($signer_uri);
77 // discoverKeyPair should've thrown exception if it failed
78 assert($magicsig instanceof Magicsig);
79 } elseif (!$magicsig instanceof Magicsig) { // No discovery request, so we'll give up.
80 throw new ServerException(sprintf('No public key found for profile (id==%d)', $profile->id));
86 * Get the Salmon keypair from a URI, uses XRD Discovery etc.
88 * @return Magicsig with loaded keypair
90 public function discoverKeyPair($signer_uri)
92 $disco = new Discovery();
94 // Throws exception on lookup problems
95 $xrd = $disco->lookup($signer_uri);
97 $link = $xrd->get(Magicsig::PUBLICKEYREL);
100 throw new Exception(_m('Unable to locate signer public key.'));
103 // We have a public key element, let's hope it has proper key data.
105 $parts = explode(',', $link->href);
106 if (count($parts) == 2) {
107 $keypair = $parts[1];
109 // Backwards compatibility check for separator bug in 0.9.0
110 $parts = explode(';', $link->href);
111 if (count($parts) == 2) {
112 $keypair = $parts[1];
116 if ($keypair === false) {
117 // For debugging clarity. Keypair did not pass count()-check above.
118 // TRANS: Exception when public key was not properly formatted.
119 throw new Exception(_m('Incorrectly formatted public key element.'));
122 $magicsig = Magicsig::fromString($keypair);
123 if (!$magicsig instanceof Magicsig) {
124 common_debug('Salmon error: unable to parse keypair: '.var_export($keypair,true));
125 // TRANS: Exception when public key was properly formatted but not parsable.
126 throw new ServerException(_m('Retrieved Salmon keypair could not be parsed.'));
133 * The current MagicEnvelope spec as used in StatusNet 0.9.7 and later
134 * includes both the original data and some signing metadata fields as
135 * the input plaintext for the signature hash.
139 public function signingText() {
140 return implode('.', array($this->data, // this field is pre-base64'd
141 Magicsig::base64_url_encode($this->data_type),
142 Magicsig::base64_url_encode($this->encoding),
143 Magicsig::base64_url_encode($this->alg)));
148 * @param <type> $text
149 * @param <type> $mimetype
150 * @param Magicsig $magicsig Magicsig with private key available.
151 * @return MagicEnvelope object with all properties set
153 public static function signMessage($text, $mimetype, Magicsig $magicsig)
155 $magic_env = new MagicEnvelope();
157 // Prepare text and metadata for signing
158 $magic_env->data = Magicsig::base64_url_encode($text);
159 $magic_env->data_type = $mimetype;
160 $magic_env->encoding = self::ENCODING;
161 $magic_env->alg = $magicsig->getName();
162 // Get the actual signature
163 $magic_env->sig = $magicsig->sign($magic_env->signingText());
169 * Create an <me:env> XML representation of the envelope.
171 * @return string representation of XML document
173 public function toXML() {
174 $xs = new XMLStringer();
176 $xs->elementStart('me:env', array('xmlns:me' => self::NS));
177 $xs->element('me:data', array('type' => $this->data_type), $this->data);
178 $xs->element('me:encoding', null, $this->encoding);
179 $xs->element('me:alg', null, $this->alg);
180 $xs->element('me:sig', null, $this->sig);
181 $xs->elementEnd('me:env');
183 $string = $xs->getString();
184 common_debug('MagicEnvelope XML: ' . $string);
189 * Extract the contained XML payload, and insert a copy of the envelope
190 * signature data as an <me:provenance> section.
192 * @return DOMDocument of Atom entry
194 * @fixme in case of XML parsing errors, this will spew to the error log or output
196 public function getPayload()
198 $dom = new DOMDocument();
199 if (!$dom->loadXML(Magicsig::base64_url_decode($this->data))) {
200 throw new ServerException('Malformed XML in Salmon payload');
203 switch ($this->data_type) {
204 case 'application/atom+xml':
205 if ($dom->documentElement->namespaceURI !== Activity::ATOM
206 || $dom->documentElement->tagName !== 'entry') {
207 throw new ServerException(_m('Salmon post must be an Atom entry.'));
209 $prov = $dom->createElementNS(self::NS, 'me:provenance');
210 $prov->setAttribute('xmlns:me', self::NS);
211 $data = $dom->createElementNS(self::NS, 'me:data', $this->data);
212 $data->setAttribute('type', $this->data_type);
213 $prov->appendChild($data);
214 $enc = $dom->createElementNS(self::NS, 'me:encoding', $this->encoding);
215 $prov->appendChild($enc);
216 $alg = $dom->createElementNS(self::NS, 'me:alg', $this->alg);
217 $prov->appendChild($alg);
218 $sig = $dom->createElementNS(self::NS, 'me:sig', $this->sig);
219 $prov->appendChild($sig);
221 $dom->documentElement->appendChild($prov);
224 throw new ServerException('Unknown Salmon payload data type');
230 * Find the author URI referenced in the payload Atom entry.
232 * @return string URI for author
233 * @throws ServerException on failure
235 public function getAuthorUri() {
236 $doc = $this->getPayload();
238 $authors = $doc->documentElement->getElementsByTagName('author');
239 foreach ($authors as $author) {
240 $uris = $author->getElementsByTagName('uri');
241 foreach ($uris as $uri) {
242 return $uri->nodeValue;
245 throw new ServerException('No author URI found in Salmon payload data');
249 * Attempt to verify cryptographic signing for parsed envelope data.
250 * Requires network access to retrieve public key referenced by the envelope signer.
252 * Details of failure conditions are dumped to output log and not exposed to caller.
254 * @param Profile $profile profile used to get locally cached public signature key
255 * or if necessary perform discovery on.
259 public function verify(Profile $profile)
261 if ($this->alg != 'RSA-SHA256') {
262 common_log(LOG_DEBUG, "Salmon error: bad algorithm");
266 if ($this->encoding != self::ENCODING) {
267 common_log(LOG_DEBUG, "Salmon error: bad encoding");
272 if ($profile instanceof Profile) {
273 $magicsig = $this->getKeyPair($profile, true); // Do discovery too if necessary
275 $signer_uri = $this->getAuthorUri();
276 $magicsig = $this->discoverKeyPair($signer_uri);
278 } catch (Exception $e) {
279 common_log(LOG_DEBUG, "Salmon error: ".$e->getMessage());
283 return $magicsig->verify($this->signingText(), $this->sig);
287 * Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
289 * @param DOMDocument $dom
290 * @return mixed associative array of envelope data, or false on unrecognized input
292 * @fixme may give fatal errors if some elements are missing
294 protected function fromDom(DOMDocument $dom)
296 $env_element = $dom->getElementsByTagNameNS(self::NS, 'env')->item(0);
298 $env_element = $dom->getElementsByTagNameNS(self::NS, 'provenance')->item(0);
305 $data_element = $env_element->getElementsByTagNameNS(self::NS, 'data')->item(0);
306 $sig_element = $env_element->getElementsByTagNameNS(self::NS, 'sig')->item(0);
308 $this->data = preg_replace('/\s/', '', $data_element->nodeValue);
309 $this->data_type = $data_element->getAttribute('type');
310 $this->encoding = $env_element->getElementsByTagNameNS(self::NS, 'encoding')->item(0)->nodeValue;
311 $this->alg = $env_element->getElementsByTagNameNS(self::NS, 'alg')->item(0)->nodeValue;
312 $this->sig = preg_replace('/\s/', '', $sig_element->nodeValue);
317 * Encode the given string as a signed MagicEnvelope XML document,
318 * using the keypair for the given local user profile. We can of
319 * course not sign a remote profile's slap, since we don't have the
322 * Side effects: will create and store a keypair on-demand if one
323 * hasn't already been generated for this user. This can be very slow
326 * @param string $text XML fragment to sign, assumed to be Atom
327 * @param Profile $actor Profile of a local user to use as signer
329 * @return string XML string representation of magic envelope
331 * @throws Exception on bad profile input or key generation problems
332 * @fixme if signing fails, this seems to return the original text without warning. Is there a reason for this?
334 public static function signForProfile($text, Profile $actor)
336 // We only generate keys for our local users of course, so let
337 // getUser throw an exception if the profile is not local.
338 $user = $actor->getUser();
340 // Find already stored key
341 $magicsig = Magicsig::getKV('user_id', $user->id);
342 if (!$magicsig instanceof Magicsig) {
343 // No keypair yet, let's generate one.
344 $magicsig = new Magicsig();
345 $magicsig->generate($user->id);
348 $magic_env = self::signMessage($text, 'application/atom+xml', $magicsig);
350 assert($magic_env instanceof MagicEnvelope);