src/Protocol/Salmon.php

   1 <?php
   2 /**
   3  * @file src/Protocol/Salmon.php
   4  */
   5 namespace Friendica\Protocol;
   6
   7 use Friendica\Core\Logger;
   8 use Friendica\Network\Probe;
   9 use Friendica\Util\Crypto;
  10 use Friendica\Util\Network;
  11 use Friendica\Util\XML;
  12
  13 /**
  14  * @brief Salmon Protocol class
  15  * The Salmon Protocol is a message exchange protocol running over HTTP designed to decentralize commentary
  16  * and annotations made against newsfeed articles such as blog posts.
  17  */
  18 class Salmon
  19 {
  20         /**
  21          * @param string $uri     Uniform Resource Identifier
  22          * @param string $keyhash encoded key
  23          * @return mixed
  24          */
  25         public static function getKey($uri, $keyhash)
  26         {
  27                 $ret = [];
  28
  29                 Logger::log('Fetching salmon key for '.$uri);
  30
  31                 $arr = Probe::lrdd($uri);
  32
  33                 if (is_array($arr)) {
  34                         foreach ($arr as $a) {
  35                                 if ($a['@attributes']['rel'] === 'magic-public-key') {
  36                                         $ret[] = $a['@attributes']['href'];
  37                                 }
  38                         }
  39                 } else {
  40                         return '';
  41                 }
  42
  43                 // We have found at least one key URL
  44                 // If it's inline, parse it - otherwise get the key
  45
  46                 if (count($ret) > 0) {
  47                         for ($x = 0; $x < count($ret); $x ++) {
  48                                 if (substr($ret[$x], 0, 5) === 'data:') {
  49                                         if (strstr($ret[$x], ',')) {
  50                                                 $ret[$x] = substr($ret[$x], strpos($ret[$x], ',') + 1);
  51                                         } else {
  52                                                 $ret[$x] = substr($ret[$x], 5);
  53                                         }
  54                                 } elseif (normalise_link($ret[$x]) == 'http://') {
  55                                         $ret[$x] = Network::fetchUrl($ret[$x]);
  56                                 }
  57                         }
  58                 }
  59
  60
  61                 Logger::log('Key located: ' . print_r($ret, true));
  62
  63                 if (count($ret) == 1) {
  64                         // We only found one one key so we don't care if the hash matches.
  65                         // If it's the wrong key we'll find out soon enough because
  66                         // message verification will fail. This also covers some older
  67                         // software which don't supply a keyhash. As long as they only
  68                         // have one key we'll be right.
  69
  70                         return $ret[0];
  71                 } else {
  72                         foreach ($ret as $a) {
  73                                 $hash = base64url_encode(hash('sha256', $a));
  74                                 if ($hash == $keyhash) {
  75                                         return $a;
  76                                 }
  77                         }
  78                 }
  79
  80                 return '';
  81         }
  82
  83         /**
  84          * @param array  $owner owner
  85          * @param string $url   url
  86          * @param string $slap  slap
  87          * @return integer
  88          */
  89         public static function slapper($owner, $url, $slap)
  90         {
  91                 // does contact have a salmon endpoint?
  92
  93                 if (! strlen($url)) {
  94                         return;
  95                 }
  96
  97                 if (! $owner['sprvkey']) {
  98                         Logger::log(sprintf("user '%s' (%d) does not have a salmon private key. Send failed.",
  99                         $owner['username'], $owner['uid']));
 100                         return;
 101                 }
 102
 103                 Logger::log('slapper called for '.$url.'. Data: ' . $slap);
 104
 105                 // create a magic envelope
 106
 107                 $data      = base64url_encode($slap);
 108                 $data_type = 'application/atom+xml';
 109                 $encoding  = 'base64url';
 110                 $algorithm = 'RSA-SHA256';
 111                 $keyhash   = base64url_encode(hash('sha256', self::salmonKey($owner['spubkey'])), true);
 112
 113                 $precomputed = '.' . base64url_encode($data_type) . '.' . base64url_encode($encoding) . '.' . base64url_encode($algorithm);
 114
 115                 // GNU Social format
 116                 $signature   = base64url_encode(Crypto::rsaSign($data . $precomputed, $owner['sprvkey']));
 117
 118                 // Compliant format
 119                 $signature2  = base64url_encode(Crypto::rsaSign(str_replace('=', '', $data . $precomputed), $owner['sprvkey']));
 120
 121                 // Old Status.net format
 122                 $signature3  = base64url_encode(Crypto::rsaSign($data, $owner['sprvkey']));
 123
 124                 // At first try the non compliant method that works for GNU Social
 125                 $xmldata = ["me:env" => ["me:data" => $data,
 126                                 "@attributes" => ["type" => $data_type],
 127                                 "me:encoding" => $encoding,
 128                                 "me:alg" => $algorithm,
 129                                 "me:sig" => $signature,
 130                                 "@attributes2" => ["key_id" => $keyhash]]];
 131
 132                 $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
 133
 134                 $salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
 135
 136                 // slap them
 137                 $postResult = Network::post($url, $salmon, [
 138                         'Content-type: application/magic-envelope+xml',
 139                         'Content-length: ' . strlen($salmon)
 140                 ]);
 141
 142                 $return_code = $postResult->getReturnCode();
 143
 144                 // check for success, e.g. 2xx
 145
 146                 if ($return_code > 299) {
 147                         Logger::log('GNU Social salmon failed. Falling back to compliant mode');
 148
 149                         // Now try the compliant mode that normally isn't used for GNU Social
 150                         $xmldata = ["me:env" => ["me:data" => $data,
 151                                         "@attributes" => ["type" => $data_type],
 152                                         "me:encoding" => $encoding,
 153                                         "me:alg" => $algorithm,
 154                                         "me:sig" => $signature2,
 155                                         "@attributes2" => ["key_id" => $keyhash]]];
 156
 157                         $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
 158
 159                         $salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
 160
 161                         // slap them
 162                         $postResult = Network::post($url, $salmon, [
 163                                 'Content-type: application/magic-envelope+xml',
 164                                 'Content-length: ' . strlen($salmon)
 165                         ]);
 166                         $return_code = $postResult->getReturnCode();
 167                 }
 168
 169                 if ($return_code > 299) {
 170                         Logger::log('compliant salmon failed. Falling back to old status.net');
 171
 172                         // Last try. This will most likely fail as well.
 173                         $xmldata = ["me:env" => ["me:data" => $data,
 174                                         "@attributes" => ["type" => $data_type],
 175                                         "me:encoding" => $encoding,
 176                                         "me:alg" => $algorithm,
 177                                         "me:sig" => $signature3,
 178                                         "@attributes2" => ["key_id" => $keyhash]]];
 179
 180                         $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
 181
 182                         $salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
 183
 184                         // slap them
 185                         $postResult = Network::post($url, $salmon, [
 186                                 'Content-type: application/magic-envelope+xml',
 187                                 'Content-length: ' . strlen($salmon)]);
 188                         $return_code = $postResult->getReturnCode();
 189                 }
 190
 191                 Logger::log('slapper for '.$url.' returned ' . $return_code);
 192
 193                 if (! $return_code) {
 194                         return -1;
 195                 }
 196
 197                 if (($return_code == 503) && (stristr($postResult->getHeader(), 'retry-after'))) {
 198                         return -1;
 199                 }
 200
 201                 return (($return_code >= 200) && ($return_code < 300)) ? 0 : 1;
 202         }
 203
 204         /**
 205          * @param string $pubkey public key
 206          * @return string
 207          */
 208         public static function salmonKey($pubkey)
 209         {
 210                 Crypto::pemToMe($pubkey, $m, $e);
 211                 return 'RSA' . '.' . base64url_encode($m, true) . '.' . base64url_encode($e, true);
 212         }
 213 }