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($dom)) {
57 throw new ServerException('Could not load MagicEnvelope from DOM');
63 * Get the Salmon keypair from a URI, uses XRD Discovery etc.
65 * @return Magicsig with loaded keypair
67 public function getKeyPair($signer_uri)
69 $disco = new Discovery();
71 // Throws exception on lookup problems
72 $xrd = $disco->lookup($signer_uri);
74 $link = $xrd->get(Magicsig::PUBLICKEYREL);
77 throw new Exception(_m('Unable to locate signer public key.'));
80 // We have a public key element, let's hope it has proper key data.
82 $parts = explode(',', $link->href);
83 if (count($parts) == 2) {
86 // Backwards compatibility check for separator bug in 0.9.0
87 $parts = explode(';', $link->href);
88 if (count($parts) == 2) {
93 if ($keypair === false) {
94 // For debugging clarity. Keypair did not pass count()-check above.
95 // TRANS: Exception when public key was not properly formatted.
96 throw new Exception(_m('Incorrectly formatted public key element.'));
99 $magicsig = Magicsig::fromString($keypair);
100 if (!$magicsig instanceof Magicsig) {
101 common_debug('Salmon error: unable to parse keypair: '.var_export($keypair,true));
102 // TRANS: Exception when public key was properly formatted but not parsable.
103 throw new ServerException(_m('Retrieved Salmon keypair could not be parsed.'));
110 * The current MagicEnvelope spec as used in StatusNet 0.9.7 and later
111 * includes both the original data and some signing metadata fields as
112 * the input plaintext for the signature hash.
116 public function signingText() {
117 return implode('.', array($this->data, // this field is pre-base64'd
118 Magicsig::base64_url_encode($this->data_type),
119 Magicsig::base64_url_encode($this->encoding),
120 Magicsig::base64_url_encode($this->alg)));
125 * @param <type> $text
126 * @param <type> $mimetype
127 * @param Magicsig $magicsig Magicsig with private key available.
128 * @return MagicEnvelope object with all properties set
130 public static function signMessage($text, $mimetype, Magicsig $magicsig)
132 $magic_env = new MagicEnvelope();
134 // Prepare text and metadata for signing
135 $magic_env->data = Magicsig::base64_url_encode($text);
136 $magic_env->data_type = $mimetype;
137 $magic_env->encoding = self::ENCODING;
138 $magic_env->alg = $magicsig->getName();
139 // Get the actual signature
140 $magic_env->sig = $magicsig->sign($magic_env->signingText());
146 * Create an <me:env> XML representation of the envelope.
148 * @return string representation of XML document
150 public function toXML() {
151 $xs = new XMLStringer();
153 $xs->elementStart('me:env', array('xmlns:me' => self::NS));
154 $xs->element('me:data', array('type' => $this->data_type), $this->data);
155 $xs->element('me:encoding', null, $this->encoding);
156 $xs->element('me:alg', null, $this->alg);
157 $xs->element('me:sig', null, $this->sig);
158 $xs->elementEnd('me:env');
160 $string = $xs->getString();
161 common_debug('MagicEnvelope XML: ' . $string);
166 * Extract the contained XML payload, and insert a copy of the envelope
167 * signature data as an <me:provenance> section.
169 * @return string representation of modified XML document
171 * @fixme in case of XML parsing errors, this will spew to the error log or output
173 public function unfold()
175 $dom = new DOMDocument();
176 $dom->loadXML(Magicsig::base64_url_decode($this->data));
178 if ($dom->documentElement->tagName != 'entry') {
182 $prov = $dom->createElementNS(self::NS, 'me:provenance');
183 $prov->setAttribute('xmlns:me', self::NS);
184 $data = $dom->createElementNS(self::NS, 'me:data', $this->data);
185 $data->setAttribute('type', $this->data_type);
186 $prov->appendChild($data);
187 $enc = $dom->createElementNS(self::NS, 'me:encoding', $this->encoding);
188 $prov->appendChild($enc);
189 $alg = $dom->createElementNS(self::NS, 'me:alg', $this->alg);
190 $prov->appendChild($alg);
191 $sig = $dom->createElementNS(self::NS, 'me:sig', $this->sig);
192 $prov->appendChild($sig);
194 $dom->documentElement->appendChild($prov);
196 return $dom->saveXML();
200 * Find the author URI referenced in the given Atom entry.
202 * @param string $text string containing Atom entry XML
203 * @return mixed URI string or false if XML parsing fails, or null if no author URI can be found
205 * @fixme XML parsing failures will spew to error logs/output
207 public function getAuthorUri($text) {
208 $doc = new DOMDocument();
209 if (!$doc->loadXML($text)) {
213 if ($doc->documentElement->tagName == 'entry') {
214 $authors = $doc->documentElement->getElementsByTagName('author');
215 foreach ($authors as $author) {
216 $uris = $author->getElementsByTagName('uri');
217 foreach ($uris as $uri) {
218 return $uri->nodeValue;
225 * Attempt to verify cryptographic signing for parsed envelope data.
226 * Requires network access to retrieve public key referenced by the envelope signer.
228 * Details of failure conditions are dumped to output log and not exposed to caller.
232 public function verify()
234 if ($this->alg != 'RSA-SHA256') {
235 common_log(LOG_DEBUG, "Salmon error: bad algorithm");
239 if ($this->encoding != self::ENCODING) {
240 common_log(LOG_DEBUG, "Salmon error: bad encoding");
244 // $this->data is base64_url_encoded and should contain XML which is passed to getAuthorUri
245 $text = Magicsig::base64_url_decode($this->data);
246 $signer_uri = $this->getAuthorUri($text);
249 $magicsig = $this->getKeyPair($signer_uri);
250 } catch (Exception $e) {
251 common_log(LOG_DEBUG, "Salmon error: ".$e->getMessage());
255 return $magicsig->verify($this->signingText(), $this->sig);
259 * Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
261 * @param DOMDocument $dom
262 * @return mixed associative array of envelope data, or false on unrecognized input
264 * @fixme may give fatal errors if some elements are missing
266 protected function fromDom(DOMDocument $dom)
268 $env_element = $dom->getElementsByTagNameNS(self::NS, 'env')->item(0);
270 $env_element = $dom->getElementsByTagNameNS(self::NS, 'provenance')->item(0);
277 $data_element = $env_element->getElementsByTagNameNS(self::NS, 'data')->item(0);
278 $sig_element = $env_element->getElementsByTagNameNS(self::NS, 'sig')->item(0);
280 $this->data = preg_replace('/\s/', '', $data_element->nodeValue);
281 $this->data_type = $data_element->getAttribute('type');
282 $this->encoding = $env_element->getElementsByTagNameNS(self::NS, 'encoding')->item(0)->nodeValue;
283 $this->alg = $env_element->getElementsByTagNameNS(self::NS, 'alg')->item(0)->nodeValue;
284 $this->sig = preg_replace('/\s/', '', $sig_element->nodeValue);
289 * Encode the given string as a signed MagicEnvelope XML document,
290 * using the keypair for the given local user profile. We can of
291 * course not sign a remote profile's slap, since we don't have the
294 * Side effects: will create and store a keypair on-demand if one
295 * hasn't already been generated for this user. This can be very slow
298 * @param string $text XML fragment to sign, assumed to be Atom
299 * @param Profile $actor Profile of a local user to use as signer
301 * @return string XML string representation of magic envelope
303 * @throws Exception on bad profile input or key generation problems
304 * @fixme if signing fails, this seems to return the original text without warning. Is there a reason for this?
306 public static function signForProfile($text, Profile $actor)
308 // We only generate keys for our local users of course, so let
309 // getUser throw an exception if the profile is not local.
310 $user = $actor->getUser();
312 // Find already stored key
313 $magicsig = Magicsig::getKV('user_id', $user->id);
314 if (!$magicsig instanceof Magicsig) {
315 // No keypair yet, let's generate one.
316 $magicsig = new Magicsig();
317 $magicsig->generate($user->id);
320 $magic_env = self::signMessage($text, 'application/atom+xml', $magicsig);
322 assert($magicenv instanceof MagicEnvelope);