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';
36 * Get the Salmon keypair from a URI, uses XRD Discovery etc.
38 * @return Magicsig with loaded keypair
40 public function getKeyPair($signer_uri)
42 $disco = new Discovery();
44 // Throws exception on lookup problems
45 $xrd = $disco->lookup($signer_uri);
47 $link = $xrd->get(Magicsig::PUBLICKEYREL);
50 throw new Exception(_m('Unable to locate signer public key.'));
53 // We have a public key element, let's hope it has proper key data.
55 $parts = explode(',', $link->href);
56 if (count($parts) == 2) {
59 // Backwards compatibility check for separator bug in 0.9.0
60 $parts = explode(';', $link->href);
61 if (count($parts) == 2) {
66 if ($keypair === false) {
67 // For debugging clarity. Keypair did not pass count()-check above.
68 // TRANS: Exception when public key was not properly formatted.
69 throw new Exception(_m('Incorrectly formatted public key element.'));
72 $magicsig = Magicsig::fromString($keypair);
73 if (!$magicsig instanceof Magicsig) {
74 common_debug('Salmon error: unable to parse keypair: '.var_export($keypair,true));
75 // TRANS: Exception when public key was properly formatted but not parsable.
76 throw new ServerException(_m('Retrieved Salmon keypair could not be parsed.'));
83 * The current MagicEnvelope spec as used in StatusNet 0.9.7 and later
84 * includes both the original data and some signing metadata fields as
85 * the input plaintext for the signature hash.
90 public function signingText($env) {
91 return implode('.', array($env['data'], // this field is pre-base64'd
92 Magicsig::base64_url_encode($env['data_type']),
93 Magicsig::base64_url_encode($env['encoding']),
94 Magicsig::base64_url_encode($env['alg'])));
100 * @param <type> $mimetype
101 * @param <type> $keypair
102 * @return array: associative array of envelope properties
103 * @fixme it might be easier to work with storing envelope data these in the object instead of passing arrays around
105 public function signMessage($text, $mimetype, $keypair)
107 $signature_alg = Magicsig::fromString($keypair);
108 $armored_text = Magicsig::base64_url_encode($text);
110 'data' => $armored_text,
111 'encoding' => MagicEnvelope::ENCODING,
112 'data_type' => $mimetype,
114 'alg' => $signature_alg->getName()
117 $env['sig'] = $signature_alg->sign($this->signingText($env));
123 * Create an <me:env> XML representation of the envelope.
125 * @param array $env associative array with envelope data
126 * @return string representation of XML document
127 * @fixme it might be easier to work with storing envelope data these in the object instead of passing arrays around
129 public function toXML($env) {
130 $xs = new XMLStringer();
132 $xs->elementStart('me:env', array('xmlns:me' => MagicEnvelope::NS));
133 $xs->element('me:data', array('type' => $env['data_type']), $env['data']);
134 $xs->element('me:encoding', null, $env['encoding']);
135 $xs->element('me:alg', null, $env['alg']);
136 $xs->element('me:sig', null, $env['sig']);
137 $xs->elementEnd('me:env');
139 $string = $xs->getString();
140 common_debug($string);
145 * Extract the contained XML payload, and insert a copy of the envelope
146 * signature data as an <me:provenance> section.
148 * @param array $env associative array with envelope data
149 * @return string representation of modified XML document
151 * @fixme in case of XML parsing errors, this will spew to the error log or output
152 * @fixme it might be easier to work with storing envelope data these in the object instead of passing arrays around
154 public function unfold($env)
156 $dom = new DOMDocument();
157 $dom->loadXML(Magicsig::base64_url_decode($env['data']));
159 if ($dom->documentElement->tagName != 'entry') {
163 $prov = $dom->createElementNS(MagicEnvelope::NS, 'me:provenance');
164 $prov->setAttribute('xmlns:me', MagicEnvelope::NS);
165 $data = $dom->createElementNS(MagicEnvelope::NS, 'me:data', $env['data']);
166 $data->setAttribute('type', $env['data_type']);
167 $prov->appendChild($data);
168 $enc = $dom->createElementNS(MagicEnvelope::NS, 'me:encoding', $env['encoding']);
169 $prov->appendChild($enc);
170 $alg = $dom->createElementNS(MagicEnvelope::NS, 'me:alg', $env['alg']);
171 $prov->appendChild($alg);
172 $sig = $dom->createElementNS(MagicEnvelope::NS, 'me:sig', $env['sig']);
173 $prov->appendChild($sig);
175 $dom->documentElement->appendChild($prov);
177 return $dom->saveXML();
181 * Find the author URI referenced in the given Atom entry.
183 * @param string $text string containing Atom entry XML
184 * @return mixed URI string or false if XML parsing fails, or null if no author URI can be found
186 * @fixme XML parsing failures will spew to error logs/output
188 public function getAuthorUri($text) {
189 $doc = new DOMDocument();
190 if (!$doc->loadXML($text)) {
194 if ($doc->documentElement->tagName == 'entry') {
195 $authors = $doc->documentElement->getElementsByTagName('author');
196 foreach ($authors as $author) {
197 $uris = $author->getElementsByTagName('uri');
198 foreach ($uris as $uri) {
199 return $uri->nodeValue;
206 * Attempt to verify cryptographic signing for parsed envelope data.
207 * Requires network access to retrieve public key referenced by the envelope signer.
209 * Details of failure conditions are dumped to output log and not exposed to caller.
211 * @param array $env array representation of magic envelope data, as returned from MagicEnvelope::parse()
214 * @fixme it might be easier to work with storing envelope data these in the object instead of passing arrays around
216 public function verify($env)
218 if ($env['alg'] != 'RSA-SHA256') {
219 common_log(LOG_DEBUG, "Salmon error: bad algorithm");
223 if ($env['encoding'] != MagicEnvelope::ENCODING) {
224 common_log(LOG_DEBUG, "Salmon error: bad encoding");
228 $text = Magicsig::base64_url_decode($env['data']);
229 $signer_uri = $this->getAuthorUri($text);
232 $magicsig = $this->getKeyPair($signer_uri);
233 } catch (Exception $e) {
234 common_log(LOG_DEBUG, "Salmon error: ".$e->getMessage());
238 return $magicsig->verify($this->signingText($env), $env['sig']);
242 * Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
244 * @param string XML source
245 * @return mixed associative array of envelope data, or false on unrecognized input
247 * @fixme it might be easier to work with storing envelope data these in the object instead of passing arrays around
248 * @fixme will spew errors to logs or output in case of XML parse errors
249 * @fixme may give fatal errors if some elements are missing or invalid XML
250 * @fixme calling DOMDocument::loadXML statically triggers warnings in strict mode
252 public function parse($text)
254 $dom = DOMDocument::loadXML($text);
255 return $this->fromDom($dom);
259 * Extract envelope data from an XML document containing an <me:env> or <me:provenance> element.
261 * @param DOMDocument $dom
262 * @return mixed associative array of envelope data, or false on unrecognized input
264 * @fixme it might be easier to work with storing envelope data these in the object instead of passing arrays around
265 * @fixme may give fatal errors if some elements are missing
267 public function fromDom($dom)
269 $env_element = $dom->getElementsByTagNameNS(MagicEnvelope::NS, 'env')->item(0);
271 $env_element = $dom->getElementsByTagNameNS(MagicEnvelope::NS, 'provenance')->item(0);
278 $data_element = $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'data')->item(0);
279 $sig_element = $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'sig')->item(0);
281 'data' => preg_replace('/\s/', '', $data_element->nodeValue),
282 'data_type' => $data_element->getAttribute('type'),
283 'encoding' => $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'encoding')->item(0)->nodeValue,
284 'alg' => $env_element->getElementsByTagNameNS(MagicEnvelope::NS, 'alg')->item(0)->nodeValue,
285 'sig' => preg_replace('/\s/', '', $sig_element->nodeValue),