mnet/lib.php

   1 <?php // $Id$
   2 /**
   3  * Library functions for mnet
   4  *
   5  * @author  Donal McMullan  donal@catalyst.net.nz
   6  * @version 0.0.1
   7  * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
   8  * @package mnet
   9  */
  10 require_once $CFG->dirroot.'/mnet/xmlrpc/xmlparser.php';
  11 require_once $CFG->dirroot.'/mnet/peer.php';
  12 require_once $CFG->dirroot.'/mnet/environment.php';
  13
  14 /// CONSTANTS ///////////////////////////////////////////////////////////
  15
  16 define('RPC_OK',                0);
  17 define('RPC_NOSUCHFILE',        1);
  18 define('RPC_NOSUCHCLASS',       2);
  19 define('RPC_NOSUCHFUNCTION',    3);
  20 define('RPC_FORBIDDENFUNCTION', 4);
  21 define('RPC_NOSUCHMETHOD',      5);
  22 define('RPC_FORBIDDENMETHOD',   6);
  23
  24 $MNET = new mnet_environment();
  25 $MNET->init();
  26
  27 /**
  28  * Strip extraneous detail from a URL or URI and return the hostname
  29  *
  30  * @param  string  $uri  The URI of a file on the remote computer, optionally
  31  *                       including its http:// prefix like
  32  *                       http://www.example.com/index.html
  33  * @return string        Just the hostname
  34  */
  35 function mnet_get_hostname_from_uri($uri = null) {
  36     $count = preg_match("@^(?:http[s]?://)?([A-Z0-9\-\.]+).*@i", $uri, $matches);
  37     if ($count > 0) return $matches[1];
  38     return false;
  39 }
  40
  41 /**
  42  * Get the remote machine's SSL Cert
  43  *
  44  * @param  string  $uri     The URI of a file on the remote computer, including
  45  *                          its http:// or https:// prefix
  46  * @return string           A PEM formatted SSL Certificate.
  47  */
  48 function mnet_get_public_key($uri, $application=null) {
  49     global $CFG, $MNET;
  50     // The key may be cached in the mnet_set_public_key function...
  51     // check this first
  52     $key = mnet_set_public_key($uri);
  53     if ($key != false) {
  54         return $key;
  55     }
  56
  57     if (empty($application)) {
  58         $application = get_record('mnet_application', 'name', 'moodle');
  59     }
  60
  61     $rq = xmlrpc_encode_request('system/keyswap', array($CFG->wwwroot, $MNET->public_key, $application->name), array("encoding" => "utf-8"));
  62     $ch = curl_init($uri . $application->xmlrpc_server_url);
  63
  64     curl_setopt($ch, CURLOPT_TIMEOUT, 60);
  65     curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  66     curl_setopt($ch, CURLOPT_POST, true);
  67     curl_setopt($ch, CURLOPT_USERAGENT, 'Moodle');
  68     curl_setopt($ch, CURLOPT_POSTFIELDS, $rq);
  69     curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: text/xml charset=UTF-8"));
  70     curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
  71     curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
  72
  73     $res = xmlrpc_decode(curl_exec($ch));
  74
  75     // check for curl errors
  76     $curlerrno = curl_errno($ch);
  77     if ($curlerrno!=0) {
  78         debugging("Request for $uri failed with curl error $curlerrno");
  79     }
  80
  81     // check HTTP error code
  82     $info =  curl_getinfo($ch);
  83     if (!empty($info['http_code']) and ($info['http_code'] != 200)) {
  84         debugging("Request for $uri failed with HTTP code ".$info['http_code']);
  85     }
  86
  87     curl_close($ch);
  88
  89     if (!is_array($res)) { // ! error
  90         $public_certificate = $res;
  91         $credentials=array();
  92         if (strlen(trim($public_certificate))) {
  93             $credentials = openssl_x509_parse($public_certificate);
  94             $host = $credentials['subject']['CN'];
  95             if (strpos($uri, $host) !== false) {
  96                 mnet_set_public_key($uri, $public_certificate);
  97                 return $public_certificate;
  98             }
  99             else {
 100                 debugging("Request for $uri returned public key for different URI - $host");
 101             }
 102         }
 103         else {
 104             debugging("Request for $uri returned empty response");
 105         }
 106     }
 107     else {
 108         debugging( "Request for $uri returned unexpected result");
 109     }
 110     return false;
 111 }
 112
 113 /**
 114  * Store a URI's public key in a static variable, or retrieve the key for a URI
 115  *
 116  * @param  string  $uri  The URI of a file on the remote computer, including its
 117  *                       https:// prefix
 118  * @param  mixed   $key  A public key to store in the array OR null. If the key
 119  *                       is null, the function will return the previously stored
 120  *                       key for the supplied URI, should it exist.
 121  * @return mixed         A public key OR true/false.
 122  */
 123 function mnet_set_public_key($uri, $key = null) {
 124     static $keyarray = array();
 125     if (isset($keyarray[$uri]) && empty($key)) {
 126         return $keyarray[$uri];
 127     } elseif (!empty($key)) {
 128         $keyarray[$uri] = $key;
 129         return true;
 130     }
 131     return false;
 132 }
 133
 134 /**
 135  * Sign a message and return it in an XML-Signature document
 136  *
 137  * This function can sign any content, but it was written to provide a system of
 138  * signing XML-RPC request and response messages. The message will be base64
 139  * encoded, so it does not need to be text.
 140  *
 141  * We compute the SHA1 digest of the message.
 142  * We compute a signature on that digest with our private key.
 143  * We link to the public key that can be used to verify our signature.
 144  * We base64 the message data.
 145  * We identify our wwwroot - this must match our certificate's CN
 146  *
 147  * The XML-RPC document will be parceled inside an XML-SIG document, which holds
 148  * the base64_encoded XML as an object, the SHA1 digest of that document, and a
 149  * signature of that document using the local private key. This signature will
 150  * uniquely identify the RPC document as having come from this server.
 151  *
 152  * See the {@Link http://www.w3.org/TR/xmldsig-core/ XML-DSig spec} at the W3c
 153  * site
 154  *
 155  * @param  string   $message              The data you want to sign
 156  * @param  resource $privatekey           The private key to sign the response with
 157  * @return string                         An XML-DSig document
 158  */
 159 function mnet_sign_message($message, $privatekey = null) {
 160     global $CFG, $MNET;
 161     $digest = sha1($message);
 162
 163     // If the user hasn't supplied a private key (for example, one of our older,
 164     //  expired private keys, we get the current default private key and use that.
 165     if ($privatekey == null) {
 166         $privatekey = $MNET->get_private_key();
 167     }
 168
 169     // The '$sig' value below is returned by reference.
 170     // We initialize it first to stop my IDE from complaining.
 171     $sig  = '';
 172     $bool = openssl_sign($message, $sig, $privatekey); // TODO: On failure?
 173
 174     $message = '<?xml version="1.0" encoding="iso-8859-1"?>
 175     <signedMessage>
 176         <Signature Id="MoodleSignature" xmlns="http://www.w3.org/2000/09/xmldsig#">
 177             <SignedInfo>
 178                 <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
 179                 <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"/>
 180                 <Reference URI="#XMLRPC-MSG">
 181                     <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
 182                     <DigestValue>'.$digest.'</DigestValue>
 183                 </Reference>
 184             </SignedInfo>
 185             <SignatureValue>'.base64_encode($sig).'</SignatureValue>
 186             <KeyInfo>
 187                 <RetrievalMethod URI="'.$CFG->wwwroot.'/mnet/publickey.php"/>
 188             </KeyInfo>
 189         </Signature>
 190         <object ID="XMLRPC-MSG">'.base64_encode($message).'</object>
 191         <wwwroot>'.$MNET->wwwroot.'</wwwroot>
 192         <timestamp>'.time().'</timestamp>
 193     </signedMessage>';
 194     return $message;
 195 }
 196
 197 /**
 198  * Encrypt a message and return it in an XML-Encrypted document
 199  *
 200  * This function can encrypt any content, but it was written to provide a system
 201  * of encrypting XML-RPC request and response messages. The message will be
 202  * base64 encoded, so it does not need to be text - binary data should work.
 203  *
 204  * We compute the SHA1 digest of the message.
 205  * We compute a signature on that digest with our private key.
 206  * We link to the public key that can be used to verify our signature.
 207  * We base64 the message data.
 208  * We identify our wwwroot - this must match our certificate's CN
 209  *
 210  * The XML-RPC document will be parceled inside an XML-SIG document, which holds
 211  * the base64_encoded XML as an object, the SHA1 digest of that document, and a
 212  * signature of that document using the local private key. This signature will
 213  * uniquely identify the RPC document as having come from this server.
 214  *
 215  * See the {@Link http://www.w3.org/TR/xmlenc-core/ XML-ENC spec} at the W3c
 216  * site
 217  *
 218  * @param  string   $message              The data you want to sign
 219  * @param  string   $remote_certificate   Peer's certificate in PEM format
 220  * @return string                         An XML-ENC document
 221  */
 222 function mnet_encrypt_message($message, $remote_certificate) {
 223     global $MNET;
 224
 225     // Generate a key resource from the remote_certificate text string
 226     $publickey = openssl_get_publickey($remote_certificate);
 227
 228     if ( gettype($publickey) != 'resource' ) {
 229         // Remote certificate is faulty.
 230         return false;
 231     }
 232
 233     // Initialize vars
 234     $encryptedstring = '';
 235     $symmetric_keys = array();
 236
 237     //        passed by ref ->     &$encryptedstring &$symmetric_keys
 238     $bool = openssl_seal($message, $encryptedstring, $symmetric_keys, array($publickey));
 239     $message = $encryptedstring;
 240     $symmetrickey = array_pop($symmetric_keys);
 241
 242     $message = '<?xml version="1.0" encoding="iso-8859-1"?>
 243     <encryptedMessage>
 244         <EncryptedData Id="ED" xmlns="http://www.w3.org/2001/04/xmlenc#">
 245             <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#arcfour"/>
 246             <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
 247                 <ds:RetrievalMethod URI="#EK" Type="http://www.w3.org/2001/04/xmlenc#EncryptedKey"/>
 248                 <ds:KeyName>XMLENC</ds:KeyName>
 249             </ds:KeyInfo>
 250             <CipherData>
 251                 <CipherValue>'.base64_encode($message).'</CipherValue>
 252             </CipherData>
 253         </EncryptedData>
 254         <EncryptedKey Id="EK" xmlns="http://www.w3.org/2001/04/xmlenc#">
 255             <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5"/>
 256             <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
 257                 <ds:KeyName>SSLKEY</ds:KeyName>
 258             </ds:KeyInfo>
 259             <CipherData>
 260                 <CipherValue>'.base64_encode($symmetrickey).'</CipherValue>
 261             </CipherData>
 262             <ReferenceList>
 263                 <DataReference URI="#ED"/>
 264             </ReferenceList>
 265             <CarriedKeyName>XMLENC</CarriedKeyName>
 266         </EncryptedKey>
 267         <wwwroot>'.$MNET->wwwroot.'</wwwroot>
 268     </encryptedMessage>';
 269     return $message;
 270 }
 271
 272 /**
 273  * Get your SSL keys from the database, or create them (if they don't exist yet)
 274  *
 275  * Get your SSL keys from the database, or (if they don't exist yet) call
 276  * mnet_generate_keypair to create them
 277  *
 278  * @param   string  $string     The text you want to sign
 279  * @return  string              The signature over that text
 280  */
 281 function mnet_get_keypair() {
 282     global $CFG;
 283     static $keypair = null;
 284     if (!is_null($keypair)) return $keypair;
 285     if ($result = get_field('config_plugins', 'value', 'plugin', 'mnet', 'name', 'openssl')) {
 286         list($keypair['certificate'], $keypair['keypair_PEM']) = explode('@@@@@@@@', $result);
 287         $keypair['privatekey'] = openssl_pkey_get_private($keypair['keypair_PEM']);
 288         $keypair['publickey']  = openssl_pkey_get_public($keypair['certificate']);
 289         return $keypair;
 290     } else {
 291         $keypair = mnet_generate_keypair();
 292         return $keypair;
 293     }
 294 }
 295
 296 /**
 297  * Generate public/private keys and store in the config table
 298  *
 299  * Use the distinguished name provided to create a CSR, and then sign that CSR
 300  * with the same credentials. Store the keypair you create in the config table.
 301  * If a distinguished name is not provided, create one using the fullname of
 302  * 'the course with ID 1' as your organization name, and your hostname (as
 303  * detailed in $CFG->wwwroot).
 304  *
 305  * @param   array  $dn  The distinguished name of the server
 306  * @return  string      The signature over that text
 307  */
 308 function mnet_generate_keypair($dn = null, $days=28) {
 309     global $CFG, $USER;
 310
 311     // check if lifetime has been overriden
 312     if (!empty($CFG->mnetkeylifetime)) {
 313         $days = $CFG->mnetkeylifetime;
 314     }
 315
 316     $host = strtolower($CFG->wwwroot);
 317     $host = ereg_replace("^http(s)?://",'',$host);
 318     $break = strpos($host.'/' , '/');
 319     $host   = substr($host, 0, $break);
 320
 321     if ($result = get_record_select('course'," id ='".SITEID."' ")) {
 322         $organization = $result->fullname;
 323     } else {
 324         $organization = 'None';
 325     }
 326
 327     $keypair = array();
 328
 329     $country  = 'NZ';
 330     $province = 'Wellington';
 331     $locality = 'Wellington';
 332     $email    = $CFG->noreplyaddress;
 333
 334     if(!empty($USER->country)) {
 335         $country  = $USER->country;
 336     }
 337     if(!empty($USER->city)) {
 338         $province = $USER->city;
 339         $locality = $USER->city;
 340     }
 341     if(!empty($USER->email)) {
 342         $email    = $USER->email;
 343     }
 344
 345     if (is_null($dn)) {
 346         $dn = array(
 347            "countryName" => $country,
 348            "stateOrProvinceName" => $province,
 349            "localityName" => $locality,
 350            "organizationName" => $organization,
 351            "organizationalUnitName" => 'Moodle',
 352            "commonName" => $CFG->wwwroot,
 353            "emailAddress" => $email
 354         );
 355     }
 356
 357     // ensure we remove trailing slashes
 358     $dn["commonName"] = preg_replace(':/$:', '', $dn["commonName"]);
 359
 360     $new_key = openssl_pkey_new();
 361     $csr_rsc = openssl_csr_new($dn, $new_key, array('private_key_bits',2048));
 362     $selfSignedCert = openssl_csr_sign($csr_rsc, null, $new_key, $days);
 363     unset($csr_rsc); // Free up the resource
 364
 365     // We export our self-signed certificate to a string.
 366     openssl_x509_export($selfSignedCert, $keypair['certificate']);
 367     openssl_x509_free($selfSignedCert);
 368
 369     // Export your public/private key pair as a PEM encoded string. You
 370     // can protect it with an optional passphrase if you wish.
 371     $export = openssl_pkey_export($new_key, $keypair['keypair_PEM'] /* , $passphrase */);
 372     openssl_pkey_free($new_key);
 373     unset($new_key); // Free up the resource
 374
 375     return $keypair;
 376 }
 377
 378 /**
 379  * Check that an IP address falls within the given network/mask
 380  * ok for export
 381  *
 382  * @param  string   $address        Dotted quad
 383  * @param  string   $network        Dotted quad
 384  * @param  string   $mask           A number, e.g. 16, 24, 32
 385  * @return bool
 386  */
 387 function ip_in_range($address, $network, $mask) {
 388    $lnetwork  = ip2long($network);
 389    $laddress  = ip2long($address);
 390
 391    $binnet    = str_pad( decbin($lnetwork),32,"0","STR_PAD_LEFT" );
 392    $firstpart = substr($binnet,0,$mask);
 393
 394    $binip     = str_pad( decbin($laddress),32,"0","STR_PAD_LEFT" );
 395    $firstip   = substr($binip,0,$mask);
 396    return(strcmp($firstpart,$firstip)==0);
 397 }
 398
 399 /**
 400  * Check that a given function (or method) in an include file has been designated
 401  * ok for export
 402  *
 403  * @param  string   $includefile    The path to the include file
 404  * @param  string   $functionname   The name of the function (or method) to
 405  *                                  execute
 406  * @param  mixed    $class          A class name, or false if we're just testing
 407  *                                  a function
 408  * @return int                      Zero (RPC_OK) if all ok - appropriate
 409  *                                  constant otherwise
 410  */
 411 function mnet_permit_rpc_call($includefile, $functionname, $class=false) {
 412     global $CFG, $MNET_REMOTE_CLIENT;
 413
 414     if (file_exists($CFG->dirroot . $includefile)) {
 415         include_once $CFG->dirroot . $includefile;
 416         // $callprefix matches the rpc convention
 417         // of not having a leading slash
 418         $callprefix = preg_replace('!^/!', '', $includefile);
 419     } else {
 420         return RPC_NOSUCHFILE;
 421     }
 422
 423     if ($functionname != clean_param($functionname, PARAM_PATH)) {
 424         // Under attack?
 425         // Todo: Should really return a much more BROKEN! response
 426         return RPC_FORBIDDENMETHOD;
 427     }
 428
 429     $id_list = $MNET_REMOTE_CLIENT->id;
 430     if (!empty($CFG->mnet_all_hosts_id)) {
 431         $id_list .= ', '.$CFG->mnet_all_hosts_id;
 432     }
 433
 434     // TODO: change to left-join so we can disambiguate:
 435     // 1. method doesn't exist
 436     // 2. method exists but is prohibited
 437     $sql = "
 438         SELECT
 439             count(r.id)
 440         FROM
 441             {$CFG->prefix}mnet_host2service h2s,
 442             {$CFG->prefix}mnet_service2rpc s2r,
 443             {$CFG->prefix}mnet_rpc r
 444         WHERE
 445             h2s.serviceid = s2r.serviceid AND
 446             s2r.rpcid = r.id AND
 447             r.xmlrpc_path = '$callprefix/$functionname' AND
 448             h2s.hostid in ($id_list) AND
 449             h2s.publish = '1'";
 450
 451     $permissionobj = record_exists_sql($sql);
 452
 453     if ($permissionobj === false && 'dangerous' != $CFG->mnet_dispatcher_mode) {
 454         return RPC_FORBIDDENMETHOD;
 455     }
 456
 457     // WE'RE LOOKING AT A CLASS/METHOD
 458     if (false != $class) {
 459         if (!class_exists($class)) {
 460             // Generate error response - unable to locate class
 461             return RPC_NOSUCHCLASS;
 462         }
 463
 464         $object = new $class();
 465
 466         if (!method_exists($object, $functionname)) {
 467             // Generate error response - unable to locate method
 468             return RPC_NOSUCHMETHOD;
 469         }
 470
 471         if (!method_exists($object, 'mnet_publishes')) {
 472             // Generate error response - the class doesn't publish
 473             // *any* methods, because it doesn't have an mnet_publishes
 474             // method
 475             return RPC_FORBIDDENMETHOD;
 476         }
 477
 478         // Get the list of published services - initialise method array
 479         $servicelist = $object->mnet_publishes();
 480         $methodapproved = false;
 481
 482         // If the method is in the list of approved methods, set the
 483         // methodapproved flag to true and break
 484         foreach($servicelist as $service) {
 485             if (in_array($functionname, $service['methods'])) {
 486                 $methodapproved = true;
 487                 break;
 488             }
 489         }
 490
 491         if (!$methodapproved) {
 492             return RPC_FORBIDDENMETHOD;
 493         }
 494
 495         // Stash the object so we can call the method on it later
 496         $MNET_REMOTE_CLIENT->object_to_call($object);
 497     // WE'RE LOOKING AT A FUNCTION
 498     } else {
 499         if (!function_exists($functionname)) {
 500             // Generate error response - unable to locate function
 501             return RPC_NOSUCHFUNCTION;
 502         }
 503
 504     }
 505
 506     return RPC_OK;
 507 }
 508
 509 function mnet_update_sso_access_control($username, $mnet_host_id, $accessctrl) {
 510     $mnethost = get_record('mnet_host', 'id', $mnet_host_id);
 511     if ($aclrecord = get_record('mnet_sso_access_control', 'username', $username, 'mnet_host_id', $mnet_host_id)) {
 512         // update
 513         $aclrecord->accessctrl = $accessctrl;
 514         if (update_record('mnet_sso_access_control', $aclrecord)) {
 515             add_to_log(SITEID, 'admin/mnet', 'update', 'admin/mnet/access_control.php',
 516                     "SSO ACL: $accessctrl user '$username' from {$mnethost->name}");
 517         } else {
 518             print_error('failedaclwrite', 'mnet', '', $username);
 519             return false;
 520         }
 521     } else {
 522         // insert
 523         $aclrecord->username = $username;
 524         $aclrecord->accessctrl = $accessctrl;
 525         $aclrecord->mnet_host_id = $mnet_host_id;
 526         if ($id = insert_record('mnet_sso_access_control', $aclrecord)) {
 527             add_to_log(SITEID, 'admin/mnet', 'add', 'admin/mnet/access_control.php',
 528                     "SSO ACL: $accessctrl user '$username' from {$mnethost->name}");
 529         } else {
 530             print_error('failedaclwrite', 'mnet', '', $username);
 531             return false;
 532         }
 533     }
 534     return true;
 535 }
 536
 537 function mnet_get_peer_host ($mnethostid) {
 538     static $hosts;
 539     if (!isset($hosts[$mnethostid])) {
 540         $host = get_record('mnet_host', 'id', $mnethostid);
 541         $hosts[$mnethostid] = $host;
 542     }
 543     return $hosts[$mnethostid];
 544 }
 545
 546 /**
 547  * Inline function to modify a url string so that mnet users are requested to
 548  * log in at their mnet identity provider (if they are not already logged in)
 549  * before ultimately being directed to the original url.
 550  *
 551  * uses global MNETIDPJUMPURL the url which user should initially be directed to
 552  *     MNETIDPJUMPURL is a URL associated with a moodle networking peer when it
 553  *     is fulfiling a role as an identity provider (IDP). Different urls for
 554  *     different peers, the jumpurl is formed partly from the IDP's webroot, and
 555  *     partly from a predefined local path within that webwroot.
 556  *     The result of the user hitting MNETIDPJUMPURL is that they will be asked
 557  *     to login (at their identity provider (if they aren't already)), mnet
 558  *     will prepare the necessary authentication information, then redirect
 559  *     them back to somewhere at the content provider(CP) moodle (this moodle)
 560  * @param array $url array with 2 elements
 561  *     0 - context the url was taken from, possibly just the url, possibly href="url"
 562  *     1 - the destination url
 563  * @return string the url the remote user should be supplied with.
 564  */
 565 function mnet_sso_apply_indirection ($url) {
 566     global $MNETIDPJUMPURL;
 567
 568     $localpart='';
 569     $urlparts = parse_url($url[1]);
 570     if($urlparts) {
 571         if (isset($urlparts['path'])) {
 572             $localpart .= $urlparts['path'];
 573         }
 574         if (isset($urlparts['query'])) {
 575             $localpart .= '?'.$urlparts['query'];
 576         }
 577         if (isset($urlparts['fragment'])) {
 578             $localpart .= '#'.$urlparts['fragment'];
 579         }
 580     }
 581     $indirecturl = $MNETIDPJUMPURL . urlencode($localpart);
 582     //If we matched on more than just a url (ie an html link), return the url to an href format
 583     if ($url[0] != $url[1]) {
 584         $indirecturl = 'href="'.$indirecturl.'"';
 585     }
 586     return $indirecturl;
 587 }
 588
 589 ?>