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\Strings;
  12 use Friendica\Util\XML;
  13
  14 /**
  15  * @brief Salmon Protocol class
  16  * The Salmon Protocol is a message exchange protocol running over HTTP designed to decentralize commentary
  17  * and annotations made against newsfeed articles such as blog posts.
  18  */
  19 class Salmon
  20 {
  21         /**
  22          * @param string $uri     Uniform Resource Identifier
  23          * @param string $keyhash encoded key
  24          * @return mixed
  25          */
  26         public static function getKey($uri, $keyhash)
  27         {
  28                 $ret = [];
  29
  30                 Logger::log('Fetching salmon key for '.$uri);
  31
  32                 $arr = Probe::lrdd($uri);
  33
  34                 if (is_array($arr)) {
  35                         foreach ($arr as $a) {
  36                                 if ($a['@attributes']['rel'] === 'magic-public-key') {
  37                                         $ret[] = $a['@attributes']['href'];
  38                                 }
  39                         }
  40                 } else {
  41                         return '';
  42                 }
  43
  44                 // We have found at least one key URL
  45                 // If it's inline, parse it - otherwise get the key
  46
  47                 if (count($ret) > 0) {
  48                         for ($x = 0; $x < count($ret); $x ++) {
  49                                 if (substr($ret[$x], 0, 5) === 'data:') {
  50                                         if (strstr($ret[$x], ',')) {
  51                                                 $ret[$x] = substr($ret[$x], strpos($ret[$x], ',') + 1);
  52                                         } else {
  53                                                 $ret[$x] = substr($ret[$x], 5);
  54                                         }
  55                                 } elseif (Strings::normaliseLink($ret[$x]) == 'http://') {
  56                                         $ret[$x] = Network::fetchUrl($ret[$x]);
  57                                 }
  58                         }
  59                 }
  60
  61
  62                 Logger::log('Key located: ' . print_r($ret, true));
  63
  64                 if (count($ret) == 1) {
  65                         // We only found one one key so we don't care if the hash matches.
  66                         // If it's the wrong key we'll find out soon enough because
  67                         // message verification will fail. This also covers some older
  68                         // software which don't supply a keyhash. As long as they only
  69                         // have one key we'll be right.
  70
  71                         return $ret[0];
  72                 } else {
  73                         foreach ($ret as $a) {
  74                                 $hash = Strings::base64UrlEncode(hash('sha256', $a));
  75                                 if ($hash == $keyhash) {
  76                                         return $a;
  77                                 }
  78                         }
  79                 }
  80
  81                 return '';
  82         }
  83
  84         /**
  85          * @param array  $owner owner
  86          * @param string $url   url
  87          * @param string $slap  slap
  88          * @return integer
  89          */
  90         public static function slapper($owner, $url, $slap)
  91         {
  92                 // does contact have a salmon endpoint?
  93
  94                 if (! strlen($url)) {
  95                         return;
  96                 }
  97
  98                 if (! $owner['sprvkey']) {
  99                         Logger::log(sprintf("user '%s' (%d) does not have a salmon private key. Send failed.",
 100                         $owner['username'], $owner['uid']));
 101                         return;
 102                 }
 103
 104                 Logger::log('slapper called for '.$url.'. Data: ' . $slap);
 105
 106                 // create a magic envelope
 107
 108                 $data      = Strings::base64UrlEncode($slap);
 109                 $data_type = 'application/atom+xml';
 110                 $encoding  = 'base64url';
 111                 $algorithm = 'RSA-SHA256';
 112                 $keyhash   = Strings::base64UrlEncode(hash('sha256', self::salmonKey($owner['spubkey'])), true);
 113
 114                 $precomputed = '.' . Strings::base64UrlEncode($data_type) . '.' . Strings::base64UrlEncode($encoding) . '.' . Strings::base64UrlEncode($algorithm);
 115
 116                 // GNU Social format
 117                 $signature   = Strings::base64UrlEncode(Crypto::rsaSign($data . $precomputed, $owner['sprvkey']));
 118
 119                 // Compliant format
 120                 $signature2  = Strings::base64UrlEncode(Crypto::rsaSign(str_replace('=', '', $data . $precomputed), $owner['sprvkey']));
 121
 122                 // Old Status.net format
 123                 $signature3  = Strings::base64UrlEncode(Crypto::rsaSign($data, $owner['sprvkey']));
 124
 125                 // At first try the non compliant method that works for GNU Social
 126                 $xmldata = ["me:env" => ["me:data" => $data,
 127                                 "@attributes" => ["type" => $data_type],
 128                                 "me:encoding" => $encoding,
 129                                 "me:alg" => $algorithm,
 130                                 "me:sig" => $signature,
 131                                 "@attributes2" => ["key_id" => $keyhash]]];
 132
 133                 $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
 134
 135                 $salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
 136
 137                 // slap them
 138                 $postResult = Network::post($url, $salmon, [
 139                         'Content-type: application/magic-envelope+xml',
 140                         'Content-length: ' . strlen($salmon)
 141                 ]);
 142
 143                 $return_code = $postResult->getReturnCode();
 144
 145                 // check for success, e.g. 2xx
 146
 147                 if ($return_code > 299) {
 148                         Logger::log('GNU Social salmon failed. Falling back to compliant mode');
 149
 150                         // Now try the compliant mode that normally isn't used for GNU Social
 151                         $xmldata = ["me:env" => ["me:data" => $data,
 152                                         "@attributes" => ["type" => $data_type],
 153                                         "me:encoding" => $encoding,
 154                                         "me:alg" => $algorithm,
 155                                         "me:sig" => $signature2,
 156                                         "@attributes2" => ["key_id" => $keyhash]]];
 157
 158                         $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
 159
 160                         $salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
 161
 162                         // slap them
 163                         $postResult = Network::post($url, $salmon, [
 164                                 'Content-type: application/magic-envelope+xml',
 165                                 'Content-length: ' . strlen($salmon)
 166                         ]);
 167                         $return_code = $postResult->getReturnCode();
 168                 }
 169
 170                 if ($return_code > 299) {
 171                         Logger::log('compliant salmon failed. Falling back to old status.net');
 172
 173                         // Last try. This will most likely fail as well.
 174                         $xmldata = ["me:env" => ["me:data" => $data,
 175                                         "@attributes" => ["type" => $data_type],
 176                                         "me:encoding" => $encoding,
 177                                         "me:alg" => $algorithm,
 178                                         "me:sig" => $signature3,
 179                                         "@attributes2" => ["key_id" => $keyhash]]];
 180
 181                         $namespaces = ["me" => "http://salmon-protocol.org/ns/magic-env"];
 182
 183                         $salmon = XML::fromArray($xmldata, $xml, false, $namespaces);
 184
 185                         // slap them
 186                         $postResult = Network::post($url, $salmon, [
 187                                 'Content-type: application/magic-envelope+xml',
 188                                 'Content-length: ' . strlen($salmon)]);
 189                         $return_code = $postResult->getReturnCode();
 190                 }
 191
 192                 Logger::log('slapper for '.$url.' returned ' . $return_code);
 193
 194                 if (! $return_code) {
 195                         return -1;
 196                 }
 197
 198                 if (($return_code == 503) && (stristr($postResult->getHeader(), 'retry-after'))) {
 199                         return -1;
 200                 }
 201
 202                 return (($return_code >= 200) && ($return_code < 300)) ? 0 : 1;
 203         }
 204
 205         /**
 206          * @param string $pubkey public key
 207          * @return string
 208          */
 209         public static function salmonKey($pubkey)
 210         {
 211                 Crypto::pemToMe($pubkey, $m, $e);
 212                 return 'RSA' . '.' . Strings::base64UrlEncode($m, true) . '.' . Strings::base64UrlEncode($e, true);
 213         }
 214 }