<?php // $Id: lib.php,v 1.16.2.15 2011/11/18 01:18:51 moodlerobot Exp $
/**
 * Library functions for mnet
 *
 * @author  Donal McMullan  donal@catalyst.net.nz
 * @version 0.0.1
 * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
 * @package mnet
 */
require_once $CFG->dirroot.'/mnet/xmlrpc/xmlparser.php';
require_once $CFG->dirroot.'/mnet/peer.php';
require_once $CFG->dirroot.'/mnet/environment.php';

/// CONSTANTS ///////////////////////////////////////////////////////////

define('RPC_OK',                0);
define('RPC_NOSUCHFILE',        1);
define('RPC_NOSUCHCLASS',       2);
define('RPC_NOSUCHFUNCTION',    3);
define('RPC_FORBIDDENFUNCTION', 4);
define('RPC_NOSUCHMETHOD',      5);
define('RPC_FORBIDDENMETHOD',   6);

$MNET = new mnet_environment();
$MNET->init();

/**
 * Strip extraneous detail from a URL or URI and return the hostname
 *
 * @param  string  $uri  The URI of a file on the remote computer, optionally
 *                       including its http:// prefix like
 *                       http://www.example.com/index.html
 * @return string        Just the hostname
 */
function mnet_get_hostname_from_uri($uri = null) {
    $count = preg_match("@^(?:http[s]?://)?([A-Z0-9\-\.]+).*@i", $uri, $matches);
    if ($count > 0) return $matches[1];
    return false;
}

/**
 * Get the remote machine's SSL Cert
 *
 * @param  string  $uri     The URI of a file on the remote computer, including
 *                          its http:// or https:// prefix
 * @return string           A PEM formatted SSL Certificate.
 */
function mnet_get_public_key($uri, $application=null) {
    global $CFG, $MNET;
    // The key may be cached in the mnet_set_public_key function...
    // check this first
    $key = mnet_set_public_key($uri);
    if ($key != false) {
        return $key;
    }

    if (empty($application)) {
        $application = get_record('mnet_application', 'name', 'moodle');
    }

    $rq = xmlrpc_encode_request('system/keyswap', array($CFG->wwwroot, $MNET->public_key, $application->name), array("encoding" => "utf-8"));
    $ch = curl_init($uri . $application->xmlrpc_server_url);

    curl_setopt($ch, CURLOPT_TIMEOUT, 60);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_USERAGENT, 'Moodle');
    curl_setopt($ch, CURLOPT_POSTFIELDS, $rq);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: text/xml charset=UTF-8"));
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
// (Shirai215): Proxy環境においてMoodleネットワークのビアで新しいホストを追加する際にホストとの通信に失敗する問題 (2011/08/09)
// (Shirai215): ここから追加
    if (fs_mnet_check_usingproxy($uri)) {
        $proxy_opt = $CFG->proxyhost;
        if (!empty($CFG->proxyport)) $proxy_opt .= ':'.$CFG->proxyport;
        curl_setopt($ch, CURLOPT_PROXY, $CFG->proxyhost.':'.$CFG->proxyport);
        if (!empty($CFG->proxyuser) and !empty($CFG->proxypassword)) {
            curl_setopt($ch, CURLOPT_PROXYUSERPWD, $CFG->proxyuser.':'.$CFG->proxypassword);
        }
    }
// (Shirai215): ここまで追加

    $res = xmlrpc_decode(curl_exec($ch));

    // check for curl errors
    $curlerrno = curl_errno($ch);
    if ($curlerrno!=0) {
        debugging("Request for $uri failed with curl error $curlerrno");
    } 

    // check HTTP error code
    $info =  curl_getinfo($ch);
    if (!empty($info['http_code']) and ($info['http_code'] != 200)) {
        debugging("Request for $uri failed with HTTP code ".$info['http_code']);
    }

    curl_close($ch);

    if (!is_array($res)) { // ! error
        $public_certificate = $res;
        $credentials=array();
        if (strlen(trim($public_certificate))) {
            $credentials = openssl_x509_parse($public_certificate);
            $host = $credentials['subject']['CN'];
            if (strpos($uri, $host) !== false) {
                mnet_set_public_key($uri, $public_certificate);
                return $public_certificate;
            }
            else {
                debugging("Request for $uri returned public key for different URI - $host");
            }
        }
        else {
            debugging("Request for $uri returned empty response");
        }
    }
    else {
        debugging( "Request for $uri returned unexpected result");
    }
    return false;
}

/**
 * Store a URI's public key in a static variable, or retrieve the key for a URI
 *
 * @param  string  $uri  The URI of a file on the remote computer, including its
 *                       https:// prefix
 * @param  mixed   $key  A public key to store in the array OR null. If the key
 *                       is null, the function will return the previously stored
 *                       key for the supplied URI, should it exist.
 * @return mixed         A public key OR true/false.
 */
function mnet_set_public_key($uri, $key = null) {
    static $keyarray = array();
    if (isset($keyarray[$uri]) && empty($key)) {
        return $keyarray[$uri];
    } elseif (!empty($key)) {
        $keyarray[$uri] = $key;
        return true;
    }
    return false;
}

/**
 * Sign a message and return it in an XML-Signature document
 *
 * This function can sign any content, but it was written to provide a system of
 * signing XML-RPC request and response messages. The message will be base64
 * encoded, so it does not need to be text.
 *
 * We compute the SHA1 digest of the message.
 * We compute a signature on that digest with our private key.
 * We link to the public key that can be used to verify our signature.
 * We base64 the message data.
 * We identify our wwwroot - this must match our certificate's CN
 *
 * The XML-RPC document will be parceled inside an XML-SIG document, which holds
 * the base64_encoded XML as an object, the SHA1 digest of that document, and a
 * signature of that document using the local private key. This signature will
 * uniquely identify the RPC document as having come from this server.
 *
 * See the {@Link http://www.w3.org/TR/xmldsig-core/ XML-DSig spec} at the W3c
 * site
 *
 * @param  string   $message              The data you want to sign
 * @param  resource $privatekey           The private key to sign the response with
 * @return string                         An XML-DSig document
 */
function mnet_sign_message($message, $privatekey = null) {
    global $CFG, $MNET;
    $digest = sha1($message);

    // If the user hasn't supplied a private key (for example, one of our older,
    //  expired private keys, we get the current default private key and use that.
    if ($privatekey == null) {
        $privatekey = $MNET->get_private_key();
    }

    // The '$sig' value below is returned by reference.
    // We initialize it first to stop my IDE from complaining.
    $sig  = '';
    $bool = openssl_sign($message, $sig, $privatekey); // TODO: On failure?

    $message = '<?xml version="1.0" encoding="iso-8859-1"?>
    <signedMessage>
        <Signature Id="MoodleSignature" xmlns="http://www.w3.org/2000/09/xmldsig#">
            <SignedInfo>
                <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
                <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"/>
                <Reference URI="#XMLRPC-MSG">
                    <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
                    <DigestValue>'.$digest.'</DigestValue>
                </Reference>
            </SignedInfo>
            <SignatureValue>'.base64_encode($sig).'</SignatureValue>
            <KeyInfo>
                <RetrievalMethod URI="'.$CFG->wwwroot.'/mnet/publickey.php"/>
            </KeyInfo>
        </Signature>
        <object ID="XMLRPC-MSG">'.base64_encode($message).'</object>
        <wwwroot>'.$MNET->wwwroot.'</wwwroot>
        <timestamp>'.time().'</timestamp>
    </signedMessage>';
    return $message;
}

/**
 * Encrypt a message and return it in an XML-Encrypted document
 *
 * This function can encrypt any content, but it was written to provide a system
 * of encrypting XML-RPC request and response messages. The message will be
 * base64 encoded, so it does not need to be text - binary data should work.
 *
 * We compute the SHA1 digest of the message.
 * We compute a signature on that digest with our private key.
 * We link to the public key that can be used to verify our signature.
 * We base64 the message data.
 * We identify our wwwroot - this must match our certificate's CN
 *
 * The XML-RPC document will be parceled inside an XML-SIG document, which holds
 * the base64_encoded XML as an object, the SHA1 digest of that document, and a
 * signature of that document using the local private key. This signature will
 * uniquely identify the RPC document as having come from this server.
 *
 * See the {@Link http://www.w3.org/TR/xmlenc-core/ XML-ENC spec} at the W3c
 * site
 *
 * @param  string   $message              The data you want to sign
 * @param  string   $remote_certificate   Peer's certificate in PEM format
 * @return string                         An XML-ENC document
 */
function mnet_encrypt_message($message, $remote_certificate) {
    global $MNET;

    // Generate a key resource from the remote_certificate text string
    $publickey = openssl_get_publickey($remote_certificate);

    if ( gettype($publickey) != 'resource' ) {
        // Remote certificate is faulty.
        return false;
    }

    // Initialize vars
    $encryptedstring = '';
    $symmetric_keys = array();

    //        passed by ref ->     &$encryptedstring &$symmetric_keys
    $bool = openssl_seal($message, $encryptedstring, $symmetric_keys, array($publickey));
    $message = $encryptedstring;
    $symmetrickey = array_pop($symmetric_keys);

    $message = '<?xml version="1.0" encoding="iso-8859-1"?>
    <encryptedMessage>
        <EncryptedData Id="ED" xmlns="http://www.w3.org/2001/04/xmlenc#">
            <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#arcfour"/>
            <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                <ds:RetrievalMethod URI="#EK" Type="http://www.w3.org/2001/04/xmlenc#EncryptedKey"/>
                <ds:KeyName>XMLENC</ds:KeyName>
            </ds:KeyInfo>
            <CipherData>
                <CipherValue>'.base64_encode($message).'</CipherValue>
            </CipherData>
        </EncryptedData>
        <EncryptedKey Id="EK" xmlns="http://www.w3.org/2001/04/xmlenc#">
            <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5"/>
            <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                <ds:KeyName>SSLKEY</ds:KeyName>
            </ds:KeyInfo>
            <CipherData>
                <CipherValue>'.base64_encode($symmetrickey).'</CipherValue>
            </CipherData>
            <ReferenceList>
                <DataReference URI="#ED"/>
            </ReferenceList>
            <CarriedKeyName>XMLENC</CarriedKeyName>
        </EncryptedKey>
        <wwwroot>'.$MNET->wwwroot.'</wwwroot>
    </encryptedMessage>';
    return $message;
}

/**
 * Get your SSL keys from the database, or create them (if they don't exist yet)
 *
 * Get your SSL keys from the database, or (if they don't exist yet) call
 * mnet_generate_keypair to create them
 *
 * @param   string  $string     The text you want to sign
 * @return  string              The signature over that text
 */
function mnet_get_keypair() {
    global $CFG;
    static $keypair = null;
    if (!is_null($keypair)) return $keypair;
    if ($result = get_field('config_plugins', 'value', 'plugin', 'mnet', 'name', 'openssl')) {
        list($keypair['certificate'], $keypair['keypair_PEM']) = explode('@@@@@@@@', $result);
        $keypair['privatekey'] = openssl_pkey_get_private($keypair['keypair_PEM']);
        $keypair['publickey']  = openssl_pkey_get_public($keypair['certificate']);
        return $keypair;
    } else {
        $keypair = mnet_generate_keypair();
        return $keypair;
    }
}

/**
 * Generate public/private keys and store in the config table
 *
 * Use the distinguished name provided to create a CSR, and then sign that CSR
 * with the same credentials. Store the keypair you create in the config table.
 * If a distinguished name is not provided, create one using the fullname of
 * 'the course with ID 1' as your organization name, and your hostname (as
 * detailed in $CFG->wwwroot).
 *
 * @param   array  $dn  The distinguished name of the server
 * @return  string      The signature over that text
 */
function mnet_generate_keypair($dn = null, $days=28) {
    global $CFG, $USER;

    // check if lifetime has been overriden
    if (!empty($CFG->mnetkeylifetime)) {
        $days = $CFG->mnetkeylifetime;
    }

    $host = strtolower($CFG->wwwroot);
    $host = ereg_replace("^http(s)?://",'',$host);
    $break = strpos($host.'/' , '/');
    $host   = substr($host, 0, $break);

    if ($result = get_record_select('course'," id ='".SITEID."' ")) {
        $organization = $result->fullname;
    } else {
        $organization = 'None';
    }

    $keypair = array();

    $country  = 'NZ';
    $province = 'Wellington';
    $locality = 'Wellington';
    $email    = $CFG->noreplyaddress;

    if(!empty($USER->country)) {
        $country  = $USER->country;
    }
    if(!empty($USER->city)) {
        $province = $USER->city;
        $locality = $USER->city;
    }
    if(!empty($USER->email)) {
        $email    = $USER->email;
    }

    if (is_null($dn)) {
        $dn = array(
           "countryName" => $country,
           "stateOrProvinceName" => $province,
           "localityName" => $locality,
           "organizationName" => $organization,
           "organizationalUnitName" => 'Moodle',
           "commonName" => $CFG->wwwroot,
           "emailAddress" => $email
        );
    }

    $dnlimits = array(
           'countryName'            => 2,
           'stateOrProvinceName'    => 128,
           'localityName'           => 128,
           'organizationName'       => 64,
           'organizationalUnitName' => 64,
           'commonName'             => 64,
           'emailAddress'           => 128
    );

    foreach ($dnlimits as $key => $length) {
        $dn[$key] = substr($dn[$key], 0, $length);
    }

    // ensure we remove trailing slashes
    $dn["commonName"] = preg_replace(':/$:', '', $dn["commonName"]);

    if (!empty($CFG->opensslcnf)) { //allow specification of openssl.cnf especially for Windows installs
        $new_key = openssl_pkey_new(array("config" => $CFG->opensslcnf));
        $csr_rsc = openssl_csr_new($dn, $new_key, array("config" => $CFG->opensslcnf));
        $selfSignedCert = openssl_csr_sign($csr_rsc, null, $new_key, $days, array("config" => $CFG->opensslcnf));
    } else {
        $new_key = openssl_pkey_new();
        $csr_rsc = openssl_csr_new($dn, $new_key, array('private_key_bits',2048));
        $selfSignedCert = openssl_csr_sign($csr_rsc, null, $new_key, $days);
    }
    unset($csr_rsc); // Free up the resource

    // We export our self-signed certificate to a string.
    openssl_x509_export($selfSignedCert, $keypair['certificate']);
    openssl_x509_free($selfSignedCert);

    // Export your public/private key pair as a PEM encoded string. You
    // can protect it with an optional passphrase if you wish.
    if (!empty($CFG->opensslcnf)) { //allow specification of openssl.cnf especially for Windows installs
        $export = openssl_pkey_export($new_key, $keypair['keypair_PEM'], null, array("config" => $CFG->opensslcnf));
    } else {
        $export = openssl_pkey_export($new_key, $keypair['keypair_PEM'] /* , $passphrase */);
    }
    openssl_pkey_free($new_key);
    unset($new_key); // Free up the resource

    return $keypair;
}

/**
 * Check that an IP address falls within the given network/mask
 * ok for export
 *
 * @param  string   $address        Dotted quad
 * @param  string   $network        Dotted quad
 * @param  string   $mask           A number, e.g. 16, 24, 32
 * @return bool
 */
function ip_in_range($address, $network, $mask) {
   $lnetwork  = ip2long($network);
   $laddress  = ip2long($address);

   $binnet    = str_pad( decbin($lnetwork), 32, "0", STR_PAD_LEFT );
   $firstpart = substr($binnet,0,$mask);

   $binip     = str_pad( decbin($laddress), 32, "0", STR_PAD_LEFT );
   $firstip   = substr($binip,0,$mask);
   return(strcmp($firstpart,$firstip)==0);
}

/**
 * Check that a given function (or method) in an include file has been designated
 * ok for export
 *
 * @param  string   $includefile    The path to the include file
 * @param  string   $functionname   The name of the function (or method) to
 *                                  execute
 * @param  mixed    $class          A class name, or false if we're just testing
 *                                  a function
 * @return int                      Zero (RPC_OK) if all ok - appropriate
 *                                  constant otherwise
 */
function mnet_permit_rpc_call($includefile, $functionname, $class=false) {
    global $CFG, $MNET_REMOTE_CLIENT;

    if (file_exists($CFG->dirroot . $includefile)) {
        include_once $CFG->dirroot . $includefile;
        // $callprefix matches the rpc convention
        // of not having a leading slash
        $callprefix = preg_replace('!^/!', '', $includefile);
    } else {
        return RPC_NOSUCHFILE;
    }

    if ($functionname != clean_param($functionname, PARAM_PATH)) {
        // Under attack?
        // Todo: Should really return a much more BROKEN! response
        return RPC_FORBIDDENMETHOD;
    }

    $id_list = $MNET_REMOTE_CLIENT->id;
    if (!empty($CFG->mnet_all_hosts_id)) {
        $id_list .= ', '.$CFG->mnet_all_hosts_id;
    }

    // TODO: change to left-join so we can disambiguate:
    // 1. method doesn't exist
    // 2. method exists but is prohibited
    $sql = "
        SELECT
            count(r.id)
        FROM
            {$CFG->prefix}mnet_host2service h2s,
            {$CFG->prefix}mnet_service2rpc s2r,
            {$CFG->prefix}mnet_rpc r
        WHERE
            h2s.serviceid = s2r.serviceid AND
            s2r.rpcid = r.id AND
            r.xmlrpc_path = '$callprefix/$functionname' AND
            h2s.hostid in ($id_list) AND
            h2s.publish = '1'";

    $permission = count_records_sql($sql);

    if (!$permission && 'dangerous' != $CFG->mnet_dispatcher_mode) {
        return RPC_FORBIDDENMETHOD;
    }

    // WE'RE LOOKING AT A CLASS/METHOD
    if (false != $class) {
        if (!class_exists($class)) {
            // Generate error response - unable to locate class
            return RPC_NOSUCHCLASS;
        }

        $object = new $class();

        if (!method_exists($object, $functionname)) {
            // Generate error response - unable to locate method
            return RPC_NOSUCHMETHOD;
        }

        if (!method_exists($object, 'mnet_publishes')) {
            // Generate error response - the class doesn't publish
            // *any* methods, because it doesn't have an mnet_publishes
            // method
            return RPC_FORBIDDENMETHOD;
        }

        // Get the list of published services - initialise method array
        $servicelist = $object->mnet_publishes();
        $methodapproved = false;

        // If the method is in the list of approved methods, set the
        // methodapproved flag to true and break
        foreach($servicelist as $service) {
            if (in_array($functionname, $service['methods'])) {
                $methodapproved = true;
                break;
            }
        }

        if (!$methodapproved) {
            return RPC_FORBIDDENMETHOD;
        }

        // Stash the object so we can call the method on it later
        $MNET_REMOTE_CLIENT->object_to_call($object);
    // WE'RE LOOKING AT A FUNCTION
    } else {
        if (!function_exists($functionname)) {
            // Generate error response - unable to locate function
            return RPC_NOSUCHFUNCTION;
        }

    }

    return RPC_OK;
}

function mnet_update_sso_access_control($username, $mnet_host_id, $accessctrl) {
    $mnethost = get_record('mnet_host', 'id', $mnet_host_id);
    if ($aclrecord = get_record('mnet_sso_access_control', 'username', $username, 'mnet_host_id', $mnet_host_id)) {
        // update
        $aclrecord->accessctrl = $accessctrl;
        if (update_record('mnet_sso_access_control', $aclrecord)) {
            add_to_log(SITEID, 'admin/mnet', 'update', 'admin/mnet/access_control.php',
                    "SSO ACL: $accessctrl user '$username' from {$mnethost->name}");
        } else {
            print_error('failedaclwrite', 'mnet', '', $username);
            return false;
        }
    } else {
        // insert
        $aclrecord->username = $username;
        $aclrecord->accessctrl = $accessctrl;
        $aclrecord->mnet_host_id = $mnet_host_id;
        if ($id = insert_record('mnet_sso_access_control', $aclrecord)) {
            add_to_log(SITEID, 'admin/mnet', 'add', 'admin/mnet/access_control.php',
                    "SSO ACL: $accessctrl user '$username' from {$mnethost->name}");
        } else {
            print_error('failedaclwrite', 'mnet', '', $username);
            return false;
        }
    }
    return true;
}

function mnet_get_peer_host ($mnethostid) {
    static $hosts;
    if (!isset($hosts[$mnethostid])) {
        $host = get_record('mnet_host', 'id', $mnethostid);
        $hosts[$mnethostid] = $host;
    }
    return $hosts[$mnethostid];
}

/**
 * Inline function to modify a url string so that mnet users are requested to
 * log in at their mnet identity provider (if they are not already logged in)
 * before ultimately being directed to the original url.
 *
 * uses global MNETIDPJUMPURL the url which user should initially be directed to
 *     MNETIDPJUMPURL is a URL associated with a moodle networking peer when it
 *     is fulfiling a role as an identity provider (IDP). Different urls for
 *     different peers, the jumpurl is formed partly from the IDP's webroot, and
 *     partly from a predefined local path within that webwroot.
 *     The result of the user hitting MNETIDPJUMPURL is that they will be asked
 *     to login (at their identity provider (if they aren't already)), mnet
 *     will prepare the necessary authentication information, then redirect
 *     them back to somewhere at the content provider(CP) moodle (this moodle)
 * @param array $url array with 2 elements
 *     0 - context the url was taken from, possibly just the url, possibly href="url"
 *     1 - the destination url
 * @return string the url the remote user should be supplied with.
 */
function mnet_sso_apply_indirection ($url) {
    global $MNETIDPJUMPURL;
    global $CFG;

    $localpart='';
    $urlparts = parse_url($url[1]);
    if($urlparts) {
        if (isset($urlparts['path'])) {
            $path = $urlparts['path'];
            // if our wwwroot has a path component, need to strip that path from beginning of the
            // 'localpart' to make it relative to moodle's wwwroot
            $wwwrootparts = parse_url($CFG->wwwroot);
            if (!empty($wwwrootparts['path']) and strpos($path, $wwwrootparts['path']) === 0) {
                $path = substr($path, strlen($wwwrootparts['path']));
            }
            $localpart .= $path;
        }
        if (isset($urlparts['query'])) {
            $localpart .= '?'.$urlparts['query'];
        }
        if (isset($urlparts['fragment'])) {
            $localpart .= '#'.$urlparts['fragment'];
        }
    }
    $indirecturl = $MNETIDPJUMPURL . urlencode($localpart);
    //If we matched on more than just a url (ie an html link), return the url to an href format
    if ($url[0] != $url[1]) {
        $indirecturl = 'href="'.$indirecturl.'"';
    }
    return $indirecturl;
}

?>
