var fs = require('fs'),
    url = require('url'),
    zlib = require('zlib'),
    querystring = require('querystring'),
    Promise = require('bluebird'),
    log4js = require('log4js'), // the logger
    express = require('express'),
    xmlCrypto = require('xml-crypto'),
    xmldom = require('xmldom'),
    xmlbuilder = require('xmlbuilder'),
    crypto = require('crypto'),
    bodyParser = require('body-parser'),
    http_app = express(),
    http_server = require('http').createServer(http_app);

http_app.use(bodyParser.urlencoded({extended: true}));
http_app.use(bodyParser.json());
http_server.listen(8085, 'localhost');

// ================================================================================
// The logger
// ================================================================================

log4js.loadAppender('file');
log4js.addAppender(log4js.appenders.file(process.env.CODEQ_SAML_LOG || 'codeq-saml.log'), 'log');
var logger = log4js.getLogger('log');

var logException = function (msg, error) {
    if ((error instanceof Error) && (typeof error.stack === 'string')) msg += '\n' + error.stack;
    logger.error(msg);
};

// prevent the node from exiting because of an unhandled exception
Promise.onPossiblyUnhandledRejection(function (error) {
    logException('Unhandled promise rejection: ' + error, error);
});

process.on('uncaughtException', function (error) {
    logException('Uncaught exception: ' + error, error);
});

// ================================================================================
// SP and IdP definitions
// ================================================================================

// SP (that's us)
//---------------
    // our URL where the IdP responds with a login result
var assertionConsumerServiceURL = 'https://codeq.si/saml/assert', // must be a POST
    // our issuer ID
    SPIssuer = 'https://codeq.si/sp/201509281041',
    // our encryption key for signing requests
    privateCert = fs.readFileSync('/etc/shibboleth/sp-key.pem', 'utf8'),
    // the status value that signals a success of an operation (a SAML constant)
    SamlStatusSuccess = 'urn:oasis:names:tc:SAML:2.0:status:Success';

// IdP: idp.aai.arnes.si
//----------------------
    // the IdP's single-sign-on page URL, where a user is redirected to perform his/her login
var SSOServiceURL = 'https://idp.aai.arnes.si/simplesaml/saml2/idp/SSOService.php', // must be a GET
    // the IdP's single-logout page URL, where a user is redirected to perform his/her (global) logout
    SLOServiceURL = 'https://idp.aai.arnes.si/simplesaml/saml2/idp/SingleLogoutService.php', // must be a GET
    // the IdP's issuer ID
    IdPIssuer = 'https://idp.aai.arnes.si/idp/20090116',
    // the IdP's public certificate to verify signatures with
    IdPKeyInfoProvider = new xmlCrypto.FileKeyInfo('/etc/shibboleth/idp.crt');

/*
// IdP: idp.uni-lj.si
//--------------------
var SSOServiceURL = 'https://idp.uni-lj.si/simplesaml/saml2/idp/SSOService.php',
    SLOServiceURL = 'https://idp.uni-lj.si/simplesaml/saml2/idp/SingleLogoutService.php',
    IdPIssuer = 'https://idp.uni-lj.si/idp/20100525',
    IdPKeyInfoProvider = new xmlCrypto.FileKeyInfo('/etc/shibboleth/idp.uni-lj.si.crt');
 */

// ================================================================================
// Misc
// ================================================================================

var idChars = '0123456789abcdef',
    makeRequestId = function () {
        var idParts = [],
            i;
        for (i = 0; i < 20; i++) idParts.push(idChars[Math.floor(Math.random() * 15)]);
        return idParts.join('');
    };

var waitingLogins = {}, // maps sid to waiter
    waitingLogouts = {},
    parkedLoginRequests = {}, // maps SAML request ID to waiter
    parkedLogoutRequests = {};

var makeSamlRedirectUrl = function (serviceUrl, queryKey, queryObj, additionalData, callback) {
    var xml = null;
    try {
        xml = xmlbuilder.create(queryObj).end();
        logger.debug('Redirecting with ' + queryKey + ' to ' + serviceUrl + ':\n' + xml);
        zlib.deflateRaw(xml, function (err, buffer) {
            var svcUrl, signer, query, keys, i, key;
            if (err) {
                callback(err, null, xml);
                return;
            }
            query = {
                'SigAlg': 'http://www.w3.org/2000/09/xmldsig#rsa-sha1'
            };
            query[queryKey] = buffer.toString('base64');
            if (additionalData && (typeof additionalData === 'object')) {
                keys = Object.keys(additionalData);
                for (i = keys.length - 1; i >= 0; i--) {
                    key = keys[i];
                    query[key] = additionalData[key];
                }
            }
            signer = crypto.createSign('RSA-SHA1');
            signer.update(querystring.stringify(query));
            query.Signature = signer.sign(privateCert, 'base64');
            svcUrl = url.parse(serviceUrl);
            svcUrl.query = query;
            delete svcUrl.search;
            callback(null, url.format(svcUrl), xml);
        });
    }
    catch (e) {
        callback(e, null, xml);
    }
};

var makeWaiter = function (sid) {
    var waiter = {
        'sid': sid,
        'created': Date.now(),
        'listeners': 0
    };
    waiter.promise = new Promise(function (resolve, reject) {
        waiter.resolve = resolve;
        waiter.reject = reject;
    });
    return waiter;
};

var makeDoubleWaiter = function (sid) {
    var waiter = makeWaiter(sid);
    waiter.responsePromise = new Promise(function (resolve, reject) {
        waiter.responseResolve = resolve;
        waiter.responseReject = reject;
    });
    return waiter;
};

// ================================================================================
// XML DOM data extraction functions for SAML data
// ================================================================================

var validateXmlSignature = function (xml, signatureNode) {
    var sig = new xmlCrypto.SignedXml();
    sig.keyInfoProvider = IdPKeyInfoProvider;
    sig.loadSignature(signatureNode.toString());
    return sig.checkSignature(xml);
};

var xmlStatusOk = function (statusNode) {
    var node = statusNode.firstChild,
        attributes, i;
    while (node) {
        if (node.localName === 'StatusCode') {
            attributes = node.attributes;
            for (i = attributes.length - 1; i >= 0; i--) {
                if (attributes[i].localName === 'Value') return attributes[i].value == SamlStatusSuccess;
            }
        }
        node = node.nextSibling;
    }
    return null;
};

var parseAttributeValue = function (attributeNode) {
    var node = attributeNode.firstChild;
    while (node) {
        if (node.localName === 'AttributeValue') {
            return node.firstChild.data;
        }
        node = node.nextSibling;
    }
    return null;
};

var parseAttributes = function (attributeStatementNode) {
    var node = attributeStatementNode.firstChild,
        result = {},
        attributes, i, name;
    while (node) {
        if (node.localName === 'Attribute') {
            attributes = node.attributes;
            for (i = attributes.length - 1; i >= 0; i--) {
                if (attributes[i].localName === 'Name') {
                    name = attributes[i].value;
                    break;
                }
            }
            if (i < 0) {
                logger.error('ERROR: an attribute without a name');
            }
            else {
                result[name] = parseAttributeValue(node);
            }
        }
        node = node.nextSibling;
    }
    return result;
};

// return the NameID in the format for use with xmlbuilder
var parseNameID = function (NameIDNode) {
    var result = {},
        i, attributes;
    result['#text'] = NameIDNode.firstChild.data;
    attributes = NameIDNode.attributes;
    for (i = attributes.length - 1; i >= 0; i--) {
        switch (attributes[i].localName) {
            case 'NameQualifier': // NameID namespace
                result['@NameQualifier'] = attributes[i].value;
                break;
            case 'SPNameQualifier': // 2nd level NameID namespace
                result['@SPNameQualifier'] = attributes[i].value;
                break;
            case 'Format':
                result['@Format'] = attributes[i].value;
                break;
            case 'SPProvidedID':
                result['@SPProvidedID'] = attributes[i].value;
                break;
        }
    }
    return result;
};

var parseSubject = function (subjectNode) {
    var node = subjectNode.firstChild,
        result = {};
    while (node) {
        if (node.localName === 'NameID') {
            result['NameID'] = parseNameID(node);
        }
        node = node.nextSibling;
    }
    return result;
};

var parseAssertion = function (xml, assertionNode) {
    var node = assertionNode.firstChild,
        result = {},
        attributes, i;
    while (node) {
        switch (node.localName) {
            case 'Signature':
                result.signatureOk = validateXmlSignature(xml, node);
                break;
            case 'Subject':
                // extract presenter identifier
                result.subject = parseSubject(node);
                break;
            case 'AuthnStatement':
                // extract the session index
                attributes = node.attributes;
                for (i = attributes.length - 1; i >= 0; i--) {
                    if (attributes[i].localName === 'SessionIndex') {
                        result.SessionIndex = attributes[i].value;
                        break;
                    }
                }
                break;
            case 'AttributeStatement':
                result.attributes = parseAttributes(node);
                break;
        }
        node = node.nextSibling;
    }
    return result;
};

// ================================================================================
// SAML logout handlers
// ================================================================================

// process response to our (global) logout request
var handleLogoutResponse = function (xml, form, res) {
    var errors = [],
        issuer = null,
        status = null,
        waiter = null,
        responded = false, // don't respond if we already responded (and failed)
        doc, rootNode, attributes, i, inResponseTo, node, m;
    try {
        doc = new xmldom.DOMParser().parseFromString(xml);
        rootNode = doc.documentElement;
        if (rootNode.localName != 'LogoutResponse') {
            errors.push('not a LogoutResponse: ' + rootNode.localName);
        }
        else {
            attributes = rootNode.attributes;
            for (i = attributes.length - 1; i >= 0; i--) {
                if (attributes[i].localName === 'InResponseTo') {
                    inResponseTo = attributes[i].value;
                    break;
                }
            }
            if (!inResponseTo) errors.push('request ID that this message is a response to is missing');
            else {
                waiter = parkedLogoutRequests[inResponseTo];
                if (!waiter) errors.push('there is no session waiting on request ID ' + inResponseTo);
                else delete parkedLogoutRequests[inResponseTo];
            }
            node = rootNode.firstChild;
            while (node) {
                switch (node.localName) {
                    case 'Issuer':
                        issuer = node.firstChild.data;
                        break;
                    case 'Status':
                        status = xmlStatusOk(node);
                        break;
                    default:
//                    errors.push('Unknown/unsupported top XML node: ' + node.localName + ', prefix: ' + node.prefix);
                        break;
                }
                node = node.nextSibling;
            }
            if (issuer === null) errors.push('Issuer is not set');
            else if (issuer !== IdPIssuer) errors.push('Invalid IdP issuer: ' + issuer);
            if (status === null) errors.push('response status is not set');
            else if (!status) errors.push('response status is not OK');
        }
        if (errors.length > 0) {
            if (waiter) {
                waiter.done = Date.now();
                waiter.responseReject(new Error(errors.join(', ')));
            }
            if (errors.length > 1) m = 'Multiple errors:\n  ' + errors.join('\n  ');
            else m = 'Error: ' + errors[0];
            logger.error('Received a SAML logout response and encountered errors processing it; response:\n' + xml + '\nErrors:\n  ' + errors.join('\n  '));
        }
        else {
            if (waiter) {
                waiter.done = Date.now();
                waiter.responseResolve();
            }
            m = 'OK';
            logger.debug('Received a SAML logout response:\n' + xml);
        }
        responded = true;
        res.set('Content-Type', 'text/plain');
        res.send(m);
    }
    catch (e) {
        m = 'Error while processing a logout response: ' + e;
        logException(m + '\n' + xml, e);
        if (waiter) {
            waiter.done = Date.now();
            waiter.responseReject(e);
        }
        if (!responded) {
            res.set('Content-Type', 'text/plain');
            res.send(m);
        }
    }
};

// a third party initiated the (global) logout, process the request and redirect with a response
var handleLogoutRequest = function (xml, form, res) {
    var errors = [],
        nameId = null,
        sessionIndex = null,
        responded = false, // don't respond if we already responded (and failed)
        doc, rootNode, attributes, i, requestId, node,
        responseObj, responseId, m;
    try {
        doc = new xmldom.DOMParser().parseFromString(xml);
        rootNode = doc.documentElement;
        if (rootNode.localName != 'LogoutRequest') {
            errors.push('not a LogoutRequest: ' + rootNode.localName);
        }
        else {
            attributes = rootNode.attributes;
            for (i = attributes.length - 1; i >= 0; i--) {
                if (attributes[i].localName === 'ID') {
                    requestId = attributes[i].value;
                    break;
                }
            }
            if (!requestId) errors.push('request ID is missing');
            node = rootNode.firstChild;
            while (node) {
                switch (node.localName) {
                    case 'Issuer':
                        if (node.firstChild.data !== IdPIssuer) errors.push('ERROR: invalid IdP issuer: ' + node.firstChild.data);
                        break;
                    case 'NameID':
                        nameId = parseNameID(node);
                        break;
                    case 'SessionIndex':
                        sessionIndex = node.firstChild && node.firstChild.data;
                        break;
                }
                node = node.nextSibling;
            }
            if (!nameId) errors.push('NameID not present');
            else {
                if (!nameId['#text']) errors.push('NameID is empty');
            }
        }
        if (errors.length > 0) {
            logger.error('A third party requested a global SAML logout, but there were errors; original request:\n' + xml + '\nErrors:\n' + errors.join('\n'));
            responded = true;
            res.set('Content-Type', 'text/plain');
            res.send(errors.join('\n'));
        }
        else {
            responseId = makeRequestId();
            responseObj = {
                'samlp:LogoutResponse': {
                    '@xmlns:samlp': 'urn:oasis:names:tc:SAML:2.0:protocol',
                    '@xmlns:saml': 'urn:oasis:names:tc:SAML:2.0:assertion',
                    '@Version': '2.0',
                    '@Destination': SLOServiceURL,
                    '@ID': responseId,
                    '@IssueInstant': new Date().toISOString(),
                    '@InResponseTo': requestId,
                    'saml:Issuer': {
                        '#text': SPIssuer
                    },
                    'samlp:Status': {
                        'samlp:StatusCode': {
                            '@Value': 'urn:oasis:names:tc:SAML:2.0:status:Success'
                        }
                    }
                }
            };
            makeSamlRedirectUrl(SLOServiceURL, 'SAMLRequest', responseObj, form.RelayState ? {RelayState: form.RelayState} : null, function (err, svcUrl, responseXml) {
                if (err) {
                    logException('Error while assembling the SAML logout response; original request:\n' + xml + '\nError: ' + err, err);
                    responded = true;
                    res.set('Content-Type', 'text/plain');
                    res.send('Failed: ' + err);
                    return;
                }
                logger.debug('Responding to a third party logout request:\n' + xml + '\nResponse:\n' + responseXml);
                responded = true;
                res.redirect(svcUrl); // redirect to the IdP
            });
        }
    }
    catch (e) {
        m = 'Error while processing a third party logout request: ' + e;
        logException(m + '\n' + xml, e);
        if (!responded) {
            res.set('Content-Type', 'text/plain');
            res.send(m);
        }
    }
};

// ================================================================================
// SAML web request handlers
// ================================================================================

// redirect to login at IdP, https://codeq.si/Shibboleth.sso/Login
http_app.get('/Shibboleth.sso/Login', function (req, res) {
    var sid = req.query.sid,
        responded = false, // don't respond if we already responded (and failed)
        waiter, requestId, request;
    try {
        if (!sid) {
            logger.error('Login request without SID, query parameters: ' + JSON.stringify(req.query));
            responded = true;
            res.set('Content-Type', 'text/plain');
            res.send('SID not set');
            return;
        }
        waiter = waitingLogins[sid];
        if (!waiter) waitingLogins[sid] = waiter = makeWaiter(sid);

        requestId = makeRequestId();
        request = {
            'samlp:AuthnRequest': {
                '@xmlns:samlp': 'urn:oasis:names:tc:SAML:2.0:protocol',
                '@xmlns:saml': 'urn:oasis:names:tc:SAML:2.0:assertion',
                '@Version': '2.0',
                '@ProtocolBinding': 'urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST',
                '@AssertionConsumerServiceURL': assertionConsumerServiceURL,
                '@Destination': SSOServiceURL,
                '@ForceAuthn': 'true',
                '@ID': requestId,
                '@IssueInstant': new Date().toISOString(),
                'saml:Issuer': {
                    '#text': SPIssuer
                }
            }
        };
        makeSamlRedirectUrl(SSOServiceURL, 'SAMLRequest', request, null, function (err, svcUrl, requestXml) {
            if (err) {
                logException('Error while assembling the Login SAML request for sid=' + sid + ': ' + err, err);
                waiter.done = Date.now();
                waiter.reject(err instanceof Error ? err : new Error(err));
                responded = true;
                res.set('Content-Type', 'text/plain');
                res.send('Failed: ' + err);
                return;
            }
            logger.debug('Redirecting to IdP with a login request:\n' + requestXml);
            responded = true;
            res.redirect(svcUrl); // redirect to the IdP
            parkedLoginRequests[requestId] = waiter;
            waiter.parked = Date.now();
            waiter.requestId = requestId;
        });
    }
    catch (e) {
        logException('Exception while processing login request with query parameters ' + JSON.stringify(req.query) + ': ' + e, e);
        if (waiter) {
            waiter.done = Date.now();
            waiter.reject(e);
        }
        if (!responded) {
            res.set('Content-Type', 'text/plain');
            res.send('Error: ' + e);
        }
    }
});

// redirect to logout at IdP, https://codeq.si/Shibboleth.sso/Logout
http_app.get('/Shibboleth.sso/Logout', function (req, res) {
    var sid = req.query.sid,
        responded = false,
        waiter, requestId, request;
    try {
        if (!sid) {
            logger.error('Logout request without SID, query parameters: ' + JSON.stringify(req.query));
            responded = true;
            res.set('Content-Type', 'text/plain');
            res.send('SID not set');
            return;
        }

        waiter = waitingLogouts[sid];
        if (!waiter) waitingLogouts[sid] = waiter = makeDoubleWaiter(sid);

        waiter.promise
            .then(function (samlData) {
                requestId = makeRequestId();
                request = {
                    'samlp:LogoutRequest': {
                        '@xmlns:samlp': 'urn:oasis:names:tc:SAML:2.0:protocol',
                        '@xmlns:saml': 'urn:oasis:names:tc:SAML:2.0:assertion',
                        '@Version': '2.0',
                        '@Destination': SLOServiceURL,
                        '@ID': requestId,
                        '@IssueInstant': new Date().toISOString(),
                        'saml:Issuer': {
                            '#text': SPIssuer
                        },
                        'saml:NameID': samlData.NameID
                    }
                };
                if (samlData.SessionIndex) request['samlp:LogoutRequest']['samlp:SessionIndex'] = {'#text': samlData.SessionIndex};
                makeSamlRedirectUrl(SLOServiceURL, 'SAMLRequest', request, null, function (err, svcUrl, requestXml) {
                    if (err) {
                        logException('Error while assembling the Logout SAML request for sid=' + sid + ': ' + err, err);
                        waiter.done = Date.now();
                        waiter.responseReject(err instanceof Error ? err : new Error(err));
                        responded = true;
                        res.set('Content-Type', 'text/plain');
                        res.send('Failed: ' + err);
                        return;
                    }
                    logger.debug('Redirecting to IdP with a logout request:\n' + requestXml);
                    responded = true;
                    res.redirect(svcUrl); // redirect to the IdP
                    parkedLogoutRequests[requestId] = waiter;
                    waiter.parked = Date.now();
                    waiter.requestId = requestId;
                });
            })
            .catch(function (e) {
                logException('Exception while processing logout request: ' + e, e);
                if (waiter) {
                    if (requestId) delete parkedLogoutRequests[requestId];
                    waiter.done = Date.now();
                    waiter.responseReject(e);
                }
                responded = true;
                res.set('Content-Type', 'text/plain');
                res.send('Error: ' + e);
            })
            .done();
    }
    catch (e) {
        logException('Exception while processing logout request: ' + e, e);
        if (waiter) {
            waiter.done = Date.now();
            waiter.reject(e);
        }
        if (!responded) {
            res.set('Content-Type', 'text/plain');
            res.send('Error: ' + e);
        }
    }
});

// user logged in, read the credentials
http_app.post('/saml/assert', function (req, res) {
    var form = req.body,
        keys = [],
        errors = [],
        inResponseTo = null,
        issuer = null,
        signature = null,
        status = null,
        assertion = null,
        waiter = null,
        responded = false, // don't respond if we already responded (and failed)
        attributes, i, key, value, xml, doc, rootNode, node, NameID, SessionIndex, samlData, userData, m;
    try {
        value = form.SAMLResponse;
        if (!value) {
            errors.push('no SAMLResponse');
        }
        else {
            xml = new Buffer(value, 'base64').toString('utf8');
            doc = new xmldom.DOMParser().parseFromString(xml);
            rootNode = doc.documentElement;
            if (rootNode.localName != 'Response') {
                errors.push('the root XML node is not a Response: ' + rootNode.localName);
            }
            else {
                attributes = rootNode.attributes;
                for (i = attributes.length - 1; i >= 0; i--) {
                    if (attributes[i].localName === 'InResponseTo') {
                        inResponseTo = attributes[i].value;
                        break;
                    }
                }
                if (!inResponseTo) errors.push('request ID that this message is a response to is missing');
                else {
                    waiter = parkedLoginRequests[inResponseTo];
                    if (!waiter) errors.push('there is no session waiting on request ID ' + inResponseTo);
                    else {
                        waiter.done = Date.now();
                        delete parkedLoginRequests[inResponseTo];
                    }
                    node = rootNode.firstChild;
                    while (node) {
                        switch (node.localName) {
                            case 'Issuer':
                                issuer = node.firstChild.data;
                                break;
                            case 'Signature':
                                signature = validateXmlSignature(xml, node);
                                break;
                            case 'Status':
                                status = xmlStatusOk(node);
                                break;
                            case 'Assertion':
                                assertion = parseAssertion(xml, node);
                                break;
                            default:
//                                errors.push('Unknown/unsupported top XML node: ' + node.localName + ', prefix: ' + node.prefix + '<br>\n');
                                break;
                        }
                        node = node.nextSibling;
                    }
                    if (issuer === null) errors.push('Issuer is not set');
                    else if (issuer !== IdPIssuer) errors.push('Invalid IdP issuer: ' + issuer);
                    if (signature === null) errors.push('the response is not signed');
                    else if (!signature) errors.push('IdP signature is invalid');
                    if (status === null) errors.push('status is not set');
                    else if (!status) errors.push('response status is not OK');
                    if (!assertion) errors.push('no assertions supplied, no attributes present');
                    else {
                        if ((typeof assertion.signatureOk !== 'undefined') && (!assertion.signatureOk)) errors.push('assertion signature is invalid');
                        samlData = {};
                        node = assertion.subject;
                        if (!node) errors.push('assertion subject is not set');
                        else {
                            node = node.NameID;
                            if (!node) errors.push('assertion subject\'s NameID is not set');
                            else {
                                if (!node['#text']) errors.push('assertion subject\'s NameID is empty');
                                samlData['NameID'] = node;
                            }
                        }
                        if (assertion.SessionIndex) samlData['SessionIndex'] = assertion.SessionIndex;
                        node = assertion.attributes;
                        if (!node) errors.push('no attributes supplied');
                        else {
                            userData = {};
                            samlData.userData = userData;
                            keys = Object.keys(node);
                            for (i = keys.length - 1; i >= 0; i--) {
                                key = keys[i];
                                userData[key] = node[key];
                            }
                        }
                    }
                }
            }
        }
        if (errors.length > 0) {
            logger.debug('Errors processing a login response:\nSAMLResponse=' + value + '\nDecoded XML:\n' + xml + '\nErrors:\n' + errors.join('\n'));
            if (waiter) waiter.reject(new Error(errors.join(', ')));
            if (errors.length > 1) m = 'Multiple errors:\n  ' + errors.join('\n  ');
            else m = 'Error: ' + errors[0];
        }
        else {
            logger.debug('Received a successful login response:\n' + xml);
            if (waiter) waiter.resolve(samlData);
            m = 'OK';
        }
        responded = true;
        res.set('Content-Type', 'text/plain');
        res.send(m);
    }
    catch (e) {
        m = 'Error while processing a login response: ' + e;
        if (xml) logException(m + '\n' + xml, e);
        else if (value) logException(m + '\nSAMLResponse=' + value, e);
        else logException(m, e);
        if (!responded) {
            res.set('Content-Type', 'text/plain');
            res.send(m);
        }
    }
});

// user logged out, the GET service
http_app.get('/saml/slo', function (req, res) {
    var form = req.query,
        delegateToHandler = function (err, buffer, handler) {
            if (err) {
                logException('Error while deflating request: ' + err, err);
                res.send('Failed: ' + err);
                return;
            }
            handler(buffer.toString('utf8'), form, res);
        };
    try {
        if (form.SAMLRequest) zlib.inflateRaw(new Buffer(form.SAMLRequest, 'base64'), function (err, buffer) {
            delegateToHandler(err, buffer, handleLogoutRequest);
        });
        else if (form.SAMLResponse) zlib.inflateRaw(new Buffer(form.SAMLResponse, 'base64'), function (err, buffer) {
            delegateToHandler(err, buffer, handleLogoutResponse);
        });
        else {
            logger.error('Invalid SAML logout request/response, query string: ' + JSON.stringify(req.query));
            res.set('Content-Type', 'text/plain');
            res.send('Invalid SAML logout request/response.');
        }
    }
    catch (e) {
        logException('Error while processing a SAML logout request/response, querystring=' + JSON.stringify(req.query) + ': ' + e, e);
        try {
            res.set('Content-Type', 'text/plain');
            res.send('Error: ' + e);
        }
        catch (e2) {} // ignore
    }
});

// ================================================================================
// Web API handlers
// ================================================================================

http_app.get('/Shibboleth.sso/WaitLogin', function (req, res) {
    var sid = req.query.sid,
        waiter;
    if (!sid) {
        res.json({'code': -1, 'message': 'sid query parameter not set'});
        return;
    }
    waiter = waitingLogins[sid];
    if (!waiter) waitingLogins[sid] = waiter = makeWaiter(sid);
    waiter.listeners = waiter.listeners + 1;
    waiter.promise.then(function (jsonResponse) {
        delete waitingLogins[sid];
        res.json({'code': 0, 'message': 'OK', 'data': jsonResponse});
    }, function (err) {
        delete waitingLogins[sid];
        res.json({'code': 1, 'message': '' + err});
    }).done();
});

http_app.get('/Shibboleth.sso/WaitLogout', function (req, res) {
    var sid = req.query.sid,
        saml = req.query.saml,
        waiter, samlData;
    if (!sid) {
        res.json({'code': -1, 'message': 'sid query parameter not set'});
        return;
    }
    if (!saml) {
        res.json({'code': -2, 'message': 'saml query parameter not set'});
        return;
    }
    try {
        samlData = JSON.parse(saml);
    }
    catch (e) {
        res.json({'code': -3, 'message': 'saml query parameter is not proper JSON: ' + e});
        return;
    }

    waiter = waitingLogouts[sid];
    if (!waiter) waitingLogouts[sid] = waiter = makeDoubleWaiter(sid);
    waiter.listeners = waiter.listeners + 1;
    waiter.resolve(samlData);
    waiter.responsePromise.then(function () {
        delete waitingLogouts[sid];
        res.json({'code': 0, 'message': 'OK'});
    }, function (err) {
        delete waitingLogouts[sid];
        res.json({'code': 1, 'message': '' + err});
    }).done();
});

// ================================================================================
// A periodic cleaner: rejects and purges timed out requests
// ================================================================================

var cleanerTimer = setInterval(function () { // run every 10 seconds
    var youngestTime = Date.now() - 300000, // request timeout: 5 minutes
        keys = Object.keys(parkedLoginRequests),
        i, key, waiter;
    // parked logins: the user was already redirected at IdP for login
    for (i = keys.length - 1; i >= 0; i--) {
        key = keys[i];
        waiter = parkedLoginRequests[key];
        if (waiter.parked < youngestTime) {
            if (waiter.promise.isPending()) {
                logger.warn('A login request timed out at IdP: sid=' + waiter.sid + ', requestId=' + waiter.requestId)
                waiter.promise.reject(new Error('Request timed out waiting for IdP login reply'));
            }
            else {
                logger.info('Encountered a parked login request which has already been resolved: sid=' + waiter.sid + ', requestId=' + waiter.requestId);
            }
            delete parkedLoginRequests[key];
            delete waitingLogins[waiter.sid];
        }
    }
    // waiting logins; the user's sid was registered, but the user itself may not have been redirected at IdP for login yet
    keys = Object.keys(waitingLogins);
    for (i = keys.length - 1; i >= 0; i--) {
        key = keys[i];
        waiter = waitingLogins[key];
        if ((waiter.parked || waiter.created) < youngestTime) {
            if (waiter.promise.isPending()) {
                if (waiter.parked) logger.warn('A login request, marked as parked but not encountered among parked requests, timed out at requester: sid=' + sid + ', requestId=' + waiter.requestId);
                else logger.warn('A login request timed out at requester, with no outstanding request at IdP: sid=' + waiter.sid);
                waiter.promise.reject(new Error('Request timed out waiting for user to start the login process'));
            }
            else {
                logger.info('Encountered a waiting login request which has already been resolved: sid=' + waiter.sid + ', requestId=' + waiter.requestId);
            }
            delete waitingLogins[key];
            if (waiter.requestId) delete parkedLoginRequests[waiter.requestId];
        }
    }
    // parked logouts: the user was already redirected at IdP for logout, if the registration data was already provided, otherwise it's still waiting for redirection
    keys = Object.keys(parkedLogoutRequests);
    for (i = keys.length - 1; i >= 0; i--) {
        key = keys[i];
        waiter = parkedLogoutRequests[key];
        if (waiter.parked < youngestTime) {
            if (waiter.promise.isPending()) {
                logger.warn('A logout request timed out waiting for registration info: sid=' + waiter.sid);
                waiter.response.reject(new Error('Timed out waiting for registration info'));
                if (waiter.responsePromise.isPending()) waiter.responsePromise.reject(new Error('Timed out waiting for registration info'));
            }
            else if (waiter.responsePromise.isPending()) {
                logger.warn('A logout request timed out at IdP: sid=' + waiter.sid + ', requestId=' + waiter.requestId)
                waiter.responsePromise.reject(new Error('Request timed out waiting for IdP logout reply'));
            }
            else {
                logger.info('Encountered a parked logout request which has already been resolved: sid=' + waiter.sid + ', requestId=' + waiter.requestId);
            }
            delete parkedLogoutRequests[key];
            delete waitingLogouts[waiter.sid];
        }
    }
    // waiting logouts; the user's sid and registration data was registered, but the user itself may not have been redirected at IdP for logout yet
    keys = Object.keys(waitingLogouts);
    for (i = keys.length - 1; i >= 0; i--) {
        key = keys[i];
        waiter = waitingLogouts[key];
        if ((waiter.parked || waiter.created) < youngestTime) {
            if (waiter.promise.isPending()) {
                if (waiter.parked) logger.warn('A logout request, marked as parked but not encountered among parked requests, timed out waiting for registration info: sid=' + sid + ', requestId=' + waiter.requestId); // this should be impossible: how can you go for logout at IdP if you have no registration info?
                else logger.warn('A logout request timed out waiting for registration info, with no outstanding request at IdP: sid=' + waiter.sid);
                waiter.response.reject(new Error('Timed out waiting for registration info'));
                if (waiter.responsePromise.isPending()) waiter.responsePromise.reject(new Error('Timed out waiting for registration info'));
            }
            else if (waiter.responsePromise.isPending()) {
                logger.warn('A logout request timed out at IdP: sid=' + waiter.sid + ', requestId=' + waiter.requestId)
                waiter.responsePromise.reject(new Error('Request timed out waiting for IdP logout reply'));
            }
            else {
                logger.info('Encountered a waiting logout request which has already been resolved: sid=' + waiter.sid + ', requestId=' + waiter.requestId);
            }
            delete waitingLogouts[key];
            if (waiter.requestId) delete parkedLogoutRequests[waiter.requestId];
        }
    }
}, 10000);