cloudron-box/src/mail.js

'use strict';

exports = module.exports = {
    getStatus: getStatus,
    checkConfiguration: checkConfiguration,

    getDomains: getDomains,

    getDomain: getDomain,
    clearDomains: clearDomains,

    onDomainAdded: onDomainAdded,
    onDomainRemoved: onDomainRemoved,

    removePrivateFields: removePrivateFields,

    setDnsRecords: setDnsRecords,
    onMailFqdnChanged: onMailFqdnChanged,

    validateName: validateName,

    setMailFromValidation: setMailFromValidation,
    setCatchAllAddress: setCatchAllAddress,
    setMailRelay: setMailRelay,
    setMailEnabled: setMailEnabled,

    startMail: restartMail,
    restartMail: restartMail,
    handleCertChanged: handleCertChanged,
    getMailAuth: getMailAuth,

    sendTestMail: sendTestMail,

    listMailboxes: listMailboxes,
    removeMailboxes: removeMailboxes,
    getMailbox: getMailbox,
    addMailbox: addMailbox,
    updateMailboxOwner: updateMailboxOwner,
    removeMailbox: removeMailbox,

    getAliases: getAliases,
    setAliases: setAliases,

    getLists: getLists,
    getList: getList,
    addList: addList,
    updateList: updateList,
    removeList: removeList,
    resolveList: resolveList,

    _readDkimPublicKeySync: readDkimPublicKeySync
};

var assert = require('assert'),
    async = require('async'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    debug = require('debug')('box:mail'),
    dns = require('./native-dns.js'),
    docker = require('./docker.js'),
    domains = require('./domains.js'),
    eventlog = require('./eventlog.js'),
    hat = require('./hat.js'),
    infra = require('./infra_version.js'),
    mailboxdb = require('./mailboxdb.js'),
    maildb = require('./maildb.js'),
    mailer = require('./mailer.js'),
    net = require('net'),
    nodemailer = require('nodemailer'),
    path = require('path'),
    paths = require('./paths.js'),
    reverseProxy = require('./reverseproxy.js'),
    safe = require('safetydance'),
    settings = require('./settings.js'),
    shell = require('./shell.js'),
    smtpTransport = require('nodemailer-smtp-transport'),
    sysinfo = require('./sysinfo.js'),
    users = require('./users.js'),
    validator = require('validator'),
    _ = require('underscore');

const DNS_OPTIONS = { timeout: 5000 };
var NOOP_CALLBACK = function (error) { if (error) debug(error); };

function validateName(name) {
    assert.strictEqual(typeof name, 'string');

    if (name.length < 1) return new BoxError(BoxError.BAD_FIELD, 'mailbox name must be atleast 1 char');
    if (name.length >= 200) return new BoxError(BoxError.BAD_FIELD, 'mailbox name too long');

    // also need to consider valid LDAP characters here (e.g '+' is reserved)
    if (/[^a-zA-Z0-9.-]/.test(name)) return new BoxError(BoxError.BAD_FIELD, 'mailbox name can only contain alphanumerals and dot');

    return null;
}

function checkOutboundPort25(callback) {
    assert.strictEqual(typeof callback, 'function');

    var smtpServer = _.sample([
        'smtp.gmail.com',
        'smtp.live.com',
        'smtp.mail.yahoo.com',
        'smtp.1und1.de',
    ]);

    var relay = {
        value: 'OK',
        status: false
    };

    var client = new net.Socket();
    client.setTimeout(5000);
    client.connect(25, smtpServer);
    client.on('connect', function () {
        relay.status = true;
        relay.value = 'OK';
        client.destroy(); // do not use end() because it still triggers timeout
        callback(null, relay);
    });
    client.on('timeout', function () {
        relay.status = false;
        relay.value = `Connect to ${smtpServer} timed out. Check if port 25 (outbound) is blocked`;
        client.destroy();
        callback(new BoxError(BoxError.TIMEOUT, `Connect to ${smtpServer} timed out.`), relay);
    });
    client.on('error', function (error) {
        relay.status = false;
        relay.value = `Connect to ${smtpServer} failed: ${error.message}. Check if port 25 (outbound) is blocked`;
        client.destroy();
        callback(new BoxError(BoxError.NETWORK_ERROR, `Connect to ${smtpServer} failed.`), relay);
    });
}

function checkSmtpRelay(relay, callback) {
    var result = {
        value: 'OK',
        status: false
    };

    var options = {
        connectionTimeout: 5000,
        greetingTimeout: 5000,
        host: relay.host,
        port: relay.port
    };

    // only set auth if either username or password is provided, some relays auth based on IP (range)
    if (relay.username || relay.password) {
        options.auth = {
            user: relay.username,
            pass: relay.password
        };
    }

    if (relay.acceptSelfSignedCerts) options.tls = { rejectUnauthorized: false };

    var transporter = nodemailer.createTransport(smtpTransport(options));

    transporter.verify(function(error) {
        result.status = !error;
        if (error) {
            result.value = error.message;
            return callback(error, result);
        }

        callback(null, result);
    });
}

function verifyRelay(relay, callback) {
    assert.strictEqual(typeof relay, 'object');
    assert.strictEqual(typeof callback, 'function');

    // we used to verify cloudron-smtp with checkOutboundPort25 but that is unreliable given that we just
    // randomly select some smtp server
    if (relay.provider === 'cloudron-smtp' || relay.provider === 'noop') return callback();

    checkSmtpRelay(relay, function (error) {
        if (error) return callback(new BoxError(BoxError.BAD_FIELD, error.message));

        callback();
    });
}

function checkDkim(mailDomain, callback) {
    assert.strictEqual(typeof mailDomain, 'object');
    assert.strictEqual(typeof callback, 'function');

    const domain = mailDomain.domain;
    let dkim = {
        domain: `${mailDomain.dkimSelector}._domainkey.${domain}`,
        name: `${mailDomain.dkimSelector}._domainkey`,
        type: 'TXT',
        expected: null,
        value: null,
        status: false
    };

    var dkimKey = readDkimPublicKeySync(domain);
    if (!dkimKey) return callback(new BoxError(BoxError.FS_ERROR, `Failed to read dkim public key of ${domain}`), dkim);

    dkim.expected = 'v=DKIM1; t=s; p=' + dkimKey;

    dns.resolve(dkim.domain, dkim.type, DNS_OPTIONS, function (error, txtRecords) {
        if (error) return callback(error, dkim);

        if (txtRecords.length !== 0) {
            dkim.value = txtRecords[0].join('');
            const actual = txtToDict(dkim.value);
            dkim.status = actual.p === dkimKey;
        }

        callback(null, dkim);
    });
}

function checkSpf(domain, mailFqdn, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof callback, 'function');

    var spf = {
        domain: domain,
        name: '@',
        type: 'TXT',
        value: null,
        expected: 'v=spf1 a:' + mailFqdn + ' ~all',
        status: false
    };

    dns.resolve(spf.domain, spf.type, DNS_OPTIONS, function (error, txtRecords) {
        if (error) return callback(error, spf);

        var i;
        for (i = 0; i < txtRecords.length; i++) {
            let txtRecord = txtRecords[i].join(''); // https://agari.zendesk.com/hc/en-us/articles/202952749-How-long-can-my-SPF-record-be-
            if (txtRecord.indexOf('v=spf1 ') !== 0) continue; // not SPF
            spf.value = txtRecord;
            spf.status = spf.value.indexOf(' a:' + settings.adminFqdn()) !== -1;
            break;
        }

        if (spf.status) {
            spf.expected = spf.value;
        } else if (i !== txtRecords.length) {
            spf.expected = 'v=spf1 a:' + settings.adminFqdn() + ' ' + spf.value.slice('v=spf1 '.length);
        }

        callback(null, spf);
    });
}

function checkMx(domain, mailFqdn, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof callback, 'function');

    var mx = {
        domain: domain,
        name: '@',
        type: 'MX',
        value: null,
        expected: '10 ' + mailFqdn + '.',
        status: false
    };

    dns.resolve(mx.domain, mx.type, DNS_OPTIONS, function (error, mxRecords) {
        if (error) return callback(error, mx);
        if (mxRecords.length === 0) return callback(null, mx);

        mx.status = mxRecords.some(mx => mx.exchange === mailFqdn); // this lets use change priority and/or setup backup MX
        mx.value = mxRecords.map(function (r) { return r.priority + ' ' + r.exchange + '.'; }).join(' ');

        if (mx.status) return callback(null, mx); // MX record is "my."

        // cloudflare might create a conflict subdomain (https://support.cloudflare.com/hc/en-us/articles/360020296512-DNS-Troubleshooting-FAQ)
        dns.resolve(mxRecords[0].exchange, 'A', DNS_OPTIONS, function (error, mxIps) {
            if (error || mxIps.length !== 1) return callback(null, mx);

            sysinfo.getServerIp(function (error, ip) {
                if (error) return callback(null, mx);

                mx.status = mxIps[0] === ip;

                callback(null, mx);
            });
        });
    });
}

function txtToDict(txt) {
    var dict = {};
    txt.split(';').forEach(function(v) {
        var p = v.trim().split('=');
        dict[p[0]]=p[1];
    });
    return dict;
}

function checkDmarc(domain, callback) {
    var dmarc = {
        domain: '_dmarc.' + domain,
        name: '_dmarc',
        type: 'TXT',
        value: null,
        expected: 'v=DMARC1; p=reject; pct=100',
        status: false
    };

    dns.resolve(dmarc.domain, dmarc.type, DNS_OPTIONS, function (error, txtRecords) {
        if (error) return callback(error, dmarc);

        if (txtRecords.length !== 0) {
            dmarc.value = txtRecords[0].join('');
            const actual = txtToDict(dmarc.value);
            dmarc.status = actual.v === 'DMARC1'; // see box#666
        }

        callback(null, dmarc);
    });
}

function checkPtr(mailFqdn, callback) {
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof callback, 'function');

    var ptr = {
        domain: null,
        name: null,
        type: 'PTR',
        value: null,
        expected: mailFqdn, // any trailing '.' is added by client software (https://lists.gt.net/spf/devel/7918)
        status: false
    };

    sysinfo.getServerIp(function (error, ip) {
        if (error) return callback(error, ptr);

        ptr.domain = ip.split('.').reverse().join('.') + '.in-addr.arpa';
        ptr.name = ip;

        dns.resolve(ptr.domain, 'PTR', DNS_OPTIONS, function (error, ptrRecords) {
            if (error) return callback(error, ptr);

            if (ptrRecords.length !== 0) {
                ptr.value = ptrRecords.join(' ');
                ptr.status = ptrRecords.some(function (v) { return v === ptr.expected; });
            }

            return callback(null, ptr);
        });
    });
}

// https://raw.githubusercontent.com/jawsome/node-dnsbl/master/list.json
const RBL_LIST = [
    {
        'name': 'Abuse.ch',
        'dns': 'spam.abuse.ch',
        'site': 'http://abuse.ch/'
    },

    {
        'name': 'Barracuda',
        'dns': 'b.barracudacentral.org',
        'site': 'http://www.barracudacentral.org/rbl/removal-request'
    },
    {
        'name': 'Composite Blocking List',
        'dns': 'cbl.abuseat.org',
        'site': 'http://www.abuseat.org'
    },
    {
        'name': 'Multi SURBL',
        'dns': 'multi.surbl.org',
        'site': 'http://www.surbl.org'
    },
    {
        'name': 'Passive Spam Block List',
        'dns': 'psbl.surriel.com',
        'site': 'https://psbl.org'
    },
    {
        'name': 'Sorbs Aggregate Zone',
        'dns': 'dnsbl.sorbs.net',
        'site': 'http://dnsbl.sorbs.net/'
    },
    {
        'name': 'Sorbs spam.dnsbl Zone',
        'dns': 'spam.dnsbl.sorbs.net',
        'site': 'http://sorbs.net'
    },
    {
        'name': 'SpamCop',
        'dns': 'bl.spamcop.net',
        'site': 'http://spamcop.net'
    },
    {
        'name': 'SpamHaus Zen',
        'dns': 'zen.spamhaus.org',
        'site': 'http://spamhaus.org'
    },
    {
        'name': 'The Unsubscribe Blacklist(UBL)',
        'dns': 'ubl.unsubscore.com ',
        'site': 'http://www.lashback.com/blacklist/'
    },
    {
        'name': 'UCEPROTECT Network',
        'dns': 'dnsbl-1.uceprotect.net',
        'site': 'http://www.uceprotect.net/en'
    }
];

// this function currently only looks for black lists based on IP. TODO: also look up by domain
function checkRblStatus(domain, callback) {
    assert.strictEqual(typeof callback, 'function');

    sysinfo.getServerIp(function (error, ip) {
        if (error) return callback(error, ip);

        var flippedIp = ip.split('.').reverse().join('.');

        // https://tools.ietf.org/html/rfc5782
        async.map(RBL_LIST, function (rblServer, iteratorDone) {
            dns.resolve(flippedIp + '.' + rblServer.dns, 'A', DNS_OPTIONS, function (error, records) {
                if (error || !records) return iteratorDone(null, null);    // not listed

                debug('checkRblStatus: %s (ip: %s) is in the blacklist of %j', domain, flippedIp, rblServer);

                var result = _.extend({ }, rblServer);

                dns.resolve(flippedIp + '.' + rblServer.dns, 'TXT', DNS_OPTIONS, function (error, txtRecords) {
                    result.txtRecords = error || !txtRecords ? 'No txt record' : txtRecords.map(x => x.join(''));

                    debug('checkRblStatus: %s (error: %s) (txtRecords: %j)', domain, error, txtRecords);

                    return iteratorDone(null, result);
                });
            });
        }, function (ignoredError, blacklistedServers) {
            blacklistedServers = blacklistedServers.filter(function(b) { return b !== null; });

            debug('checkRblStatus: %s (ip: %s) servers: %j', domain, ip, blacklistedServers);

            return callback(null, { status: blacklistedServers.length === 0, ip: ip, servers: blacklistedServers });
        });
    });
}

function getStatus(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    // ensure we always have a valid toplevel properties for the api
    var results = {
        dns: {}, // { mx/dmarc/dkim/spf/ptr: { expected, value, name, domain, type, status } }
        rbl: {}, // { status, ip, servers: [{name,site,dns}]} optional. only for cloudron-smtp
        relay: {} // { status, value } always checked
    };

    function recordResult(what, func) {
        return function (callback) {
            func(function (error, result) {
                if (error) debug('Ignored error - ' + what + ':', error);

                safe.set(results, what, result || {});

                callback();
            });
        };
    }

    const mailFqdn = settings.mailFqdn();

    getDomain(domain, function (error, mailDomain) {
        if (error) return callback(error);

        let checks = [];
        if (mailDomain.enabled) {
            checks.push(
                recordResult('dns.mx', checkMx.bind(null, domain, mailFqdn)),
                recordResult('dns.dmarc', checkDmarc.bind(null, domain))
            );
        }

        if (mailDomain.relay.provider === 'cloudron-smtp') {
            // these tests currently only make sense when using Cloudron's SMTP server at this point
            checks.push(
                recordResult('dns.spf', checkSpf.bind(null, domain, mailFqdn)),
                recordResult('dns.dkim', checkDkim.bind(null, mailDomain)),
                recordResult('dns.ptr', checkPtr.bind(null, mailFqdn)),
                recordResult('relay', checkOutboundPort25),
                recordResult('rbl', checkRblStatus.bind(null, domain))
            );
        } else if (mailDomain.relay.provider !== 'noop') {
            checks.push(recordResult('relay', checkSmtpRelay.bind(null, mailDomain.relay)));
        }

        async.parallel(checks, function () {
            callback(null, results);
        });
    });
}

function checkConfiguration(callback) {
    assert.strictEqual(typeof callback, 'function');

    let messages = {};

    domains.getAll(function (error, allDomains) {
        if (error) return callback(error);

        async.eachSeries(allDomains, function (domainObject, iteratorCallback) {
            getStatus(domainObject.domain, function (error, result) {
                if (error) return iteratorCallback(error);

                let message = [];

                Object.keys(result.dns).forEach((type) => {
                    const record = result.dns[type];
                    if (!record.status) message.push(`${type.toUpperCase()} DNS record (${record.type}) did not match.\n    * Hostname: \`${record.name}\`\n    * Expected: \`${record.expected}\`\n    * Actual: \`${record.value}\``);
                });
                if (result.relay && result.relay.status === false) message.push(`Relay error: ${result.relay.value}`);
                if (result.rbl && result.rbl.status === false) { // rbl field contents is optional
                    const servers = result.rbl.servers.map((bs) => `[${bs.name}](${bs.site})`); // in markdown
                    message.push(`This server's IP \`${result.rbl.ip}\` is blacklisted in the following servers - ${servers.join(', ')}`);
                }

                if (message.length) messages[domainObject.domain] = message;

                iteratorCallback(null);
            });
        }, function (error) {
            if (error) return callback(error);

            // create bulleted list for each domain
            let markdownMessage = '';
            Object.keys(messages).forEach((domain) => {
                markdownMessage += `**${domain}**\n`;
                markdownMessage += messages[domain].map((m) => `* ${m}\n`).join('');
                markdownMessage += '\n\n';
            });

            if (markdownMessage) markdownMessage += 'Email Status is checked every 30 minutes.\n See the [troubleshooting docs](https://cloudron.io/documentation/troubleshooting/#mail-dns) for more information.\n';

            callback(null, markdownMessage); // empty message means all status checks succeeded
        });
    });
}

function createMailConfig(mailFqdn, mailDomain, callback) {
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof mailDomain, 'string');
    assert.strictEqual(typeof callback, 'function');

    debug('createMailConfig: generating mail config');

    getDomains(function (error, mailDomains) {
        if (error) return callback(error);

        const mailOutDomains = mailDomains.filter(d => d.relay.provider !== 'noop').map(d => d.domain).join(',');
        const mailInDomains = mailDomains.filter(function (d) { return d.enabled; }).map(function (d) { return d.domain; }).join(',');

        // mail_domain is used for SRS
        if (!safe.fs.writeFileSync(path.join(paths.ADDON_CONFIG_DIR, 'mail/mail.ini'),
            `mail_in_domains=${mailInDomains}\nmail_out_domains=${mailOutDomains}\nmail_server_name=${mailFqdn}\nmail_domain=${mailDomain}\n\n`, 'utf8')) {
            return callback(new BoxError(BoxError.FS_ERROR, 'Could not create mail var file:' + safe.error.message));
        }

        // enable_outbound makes plugin forward email for relayed mail. non-relayed mail always hits LMTP plugin first
        if (!safe.fs.writeFileSync(path.join(paths.ADDON_CONFIG_DIR, 'mail/smtp_forward.ini'), 'enable_outbound=false\ndomain_selector=mail_from\n', 'utf8')) {
            return callback(new BoxError(BoxError.FS_ERROR, 'Could not create smtp forward file:' + safe.error.message));
        }

        // create sections for per-domain configuration
        mailDomains.forEach(function (domain) {
            const catchAll = domain.catchAll.map(function (c) { return `${c}@${domain.domain}`; }).join(',');
            const mailFromValidation = domain.mailFromValidation;

            if (!safe.fs.appendFileSync(path.join(paths.ADDON_CONFIG_DIR, 'mail/mail.ini'),
                `[${domain.domain}]\ncatch_all=${catchAll}\nmail_from_validation=${mailFromValidation}\n\n`, 'utf8')) {
                return callback(new BoxError(BoxError.FS_ERROR, 'Could not create mail var file:' + safe.error.message));
            }

            const relay = domain.relay;

            const enableRelay = relay.provider !== 'cloudron-smtp' && relay.provider !== 'noop',
                host = relay.host || '',
                port = relay.port || 25,
                authType = relay.username ? 'plain' : '',
                username = relay.username || '',
                password = relay.password || '';

            if (!enableRelay) return;

            if (!safe.fs.appendFileSync(paths.ADDON_CONFIG_DIR + '/mail/smtp_forward.ini',
                `[${domain.domain}]\nenable_outbound=true\nhost=${host}\nport=${port}\nenable_tls=true\nauth_type=${authType}\nauth_user=${username}\nauth_pass=${password}\n\n`, 'utf8')) {
                return callback(new BoxError(BoxError.FS_ERROR, 'Could not create mail var file:' + safe.error.message));
            }
        });

        callback(null, mailInDomains.length !== 0 /* allowInbound */);
    });
}

function configureMail(mailFqdn, mailDomain, callback) {
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof mailDomain, 'string');
    assert.strictEqual(typeof callback, 'function');

    // mail (note: 2525 is hardcoded in mail container and app use this port)
    // MAIL_SERVER_NAME is the hostname of the mailserver i.e server uses these certs
    // MAIL_DOMAIN is the domain for which this server is relaying mails
    // mail container uses /app/data for backed up data and /run for restart-able data

    const tag = infra.images.mail.tag;
    const memoryLimit = 4 * 256;
    const cloudronToken = hat(8 * 128), relayToken = hat(8 * 128);

    reverseProxy.getCertificate(mailFqdn, mailDomain, function (error, bundle) {
        if (error) return callback(error);

        // the setup script copies dhparams.pem to /addons/mail
        const mailCertFilePath = path.join(paths.ADDON_CONFIG_DIR, 'mail/tls_cert.pem');
        const mailKeyFilePath = path.join(paths.ADDON_CONFIG_DIR, 'mail/tls_key.pem');

        if (!safe.child_process.execSync(`cp ${bundle.certFilePath} ${mailCertFilePath}`)) return callback(new BoxError(BoxError.FS_ERROR, 'Could not create cert file:' + safe.error.message));
        if (!safe.child_process.execSync(`cp ${bundle.keyFilePath} ${mailKeyFilePath}`)) return callback(new BoxError(BoxError.FS_ERROR, 'Could not create key file:' + safe.error.message));

        shell.exec('startMail', 'docker rm -f mail || true', function (error) {
            if (error) return callback(error);

            createMailConfig(mailFqdn, mailDomain, function (error, allowInbound) {
                if (error) return callback(error);

                var ports = allowInbound ? '-p 587:2525 -p 993:9993 -p 4190:4190 -p 25:2525' : '';

                const cmd = `docker run --restart=always -d --name="mail" \
                            --net cloudron \
                            --net-alias mail \
                            --log-driver syslog \
                            --log-opt syslog-address=udp://127.0.0.1:2514 \
                            --log-opt syslog-format=rfc5424 \
                            --log-opt tag=mail \
                            -m ${memoryLimit}m \
                            --memory-swap ${memoryLimit * 2}m \
                            --dns 172.18.0.1 \
                            --dns-search=. \
                            -e CLOUDRON_MAIL_TOKEN="${cloudronToken}" \
                            -e CLOUDRON_RELAY_TOKEN="${relayToken}" \
                            -v "${paths.MAIL_DATA_DIR}:/app/data" \
                            -v "${paths.PLATFORM_DATA_DIR}/addons/mail:/etc/mail" \
                            ${ports} \
                            --label isCloudronManaged=true \
                            --read-only -v /run -v /tmp ${tag}`;

                shell.exec('startMail', cmd, callback);
            });
        });
    });
}

function getMailAuth(callback) {
    assert.strictEqual(typeof callback, 'function');

    docker.inspect('mail', function (error, data) {
        if (error) return callback(error);

        const ip = safe.query(data, 'NetworkSettings.Networks.cloudron.IPAddress');
        if (!ip) return callback(new BoxError(BoxError.MAIL_ERROR, 'Error querying mail server IP'));

        // extract the relay token for auth
        const env = safe.query(data, 'Config.Env', null);
        if (!env) return callback(new BoxError(BoxError.MAIL_ERROR, 'Error getting mail env'));
        const tmp = env.find(function (e) { return e.indexOf('CLOUDRON_RELAY_TOKEN') === 0; });
        if (!tmp) return callback(new BoxError(BoxError.MAIL_ERROR, 'Error getting CLOUDRON_RELAY_TOKEN env var'));
        const relayToken = tmp.slice('CLOUDRON_RELAY_TOKEN'.length + 1); // +1 for the = sign
        if (!relayToken)  return callback(new BoxError(BoxError.MAIL_ERROR, 'Error parsing CLOUDRON_RELAY_TOKEN'));

        callback(null, {
            ip,
            port: constants.INTERNAL_SMTP_PORT,
            relayToken
        });
    });
}

function restartMail(callback) {
    assert.strictEqual(typeof callback, 'function');

    if (process.env.BOX_ENV === 'test' && !process.env.TEST_CREATE_INFRA) return callback();

    debug(`restartMail: restarting mail container with ${settings.mailFqdn()} ${settings.adminDomain()}`);
    configureMail(settings.mailFqdn(), settings.adminDomain(), callback);
}

function restartMailIfActivated(callback) {
    assert.strictEqual(typeof callback, 'function');

    users.isActivated(function (error, activated) {
        if (error) return callback(error);

        if (!activated) {
            debug('restartMailIfActivated: skipping restart of mail container since Cloudron is not activated yet');
            return callback(); // not provisioned yet, do not restart container after dns setup
        }

        restartMail(callback);
    });
}

function handleCertChanged(callback) {
    assert.strictEqual(typeof callback, 'function');

    debug('handleCertChanged: will restart if activated');
    restartMailIfActivated(callback);
}

function getDomain(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    maildb.get(domain, function (error, result) {
        if (error) return callback(error);

        return callback(null, result);
    });
}

function getDomains(callback) {
    assert.strictEqual(typeof callback, 'function');

    maildb.list(function (error, results) {
        if (error) return callback(error);

        return callback(null, results);
    });
}

// https://agari.zendesk.com/hc/en-us/articles/202952749-How-long-can-my-SPF-record-be-
function txtRecordsWithSpf(domain, mailFqdn, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof callback, 'function');

    domains.getDnsRecords('', domain, 'TXT', function (error, txtRecords) {
        if (error) return error;

        debug('txtRecordsWithSpf: current txt records - %j', txtRecords);

        var i, matches, validSpf;

        for (i = 0; i < txtRecords.length; i++) {
            matches = txtRecords[i].match(/^("?v=spf1) /); // DO backend may return without quotes
            if (matches === null) continue;

            // this won't work if the entry is arbitrarily "split" across quoted strings
            validSpf = txtRecords[i].indexOf('a:' + mailFqdn) !== -1;
            break; // there can only be one SPF record
        }

        if (validSpf) return callback(null, null);

        if (!matches) { // no spf record was found, create one
            txtRecords.push('"v=spf1 a:' + mailFqdn + ' ~all"');
            debug('txtRecordsWithSpf: adding txt record');
        } else { // just add ourself
            txtRecords[i] = matches[1] + ' a:' + mailFqdn + txtRecords[i].slice(matches[1].length);
            debug('txtRecordsWithSpf: inserting txt record');
        }

        return callback(null, txtRecords);
    });
}

function ensureDkimKeySync(mailDomain) {
    assert.strictEqual(typeof mailDomain, 'object');

    const domain = mailDomain.domain;
    const dkimPath = path.join(paths.MAIL_DATA_DIR, `dkim/${domain}`);
    const dkimPrivateKeyFile = path.join(dkimPath, 'private');
    const dkimPublicKeyFile = path.join(dkimPath, 'public');
    const dkimSelectorFile = path.join(dkimPath, 'selector');

    if (safe.fs.existsSync(dkimPublicKeyFile) &&
        safe.fs.existsSync(dkimPublicKeyFile) &&
        safe.fs.existsSync(dkimPublicKeyFile)) {
        debug(`Reusing existing DKIM keys for ${domain}`);
        return null;
    }

    debug(`Generating new DKIM keys for ${domain}`);

    if (!safe.fs.mkdirSync(dkimPath) && safe.error.code !== 'EEXIST') {
        debug('Error creating dkim.', safe.error);
        return new BoxError(BoxError.FS_ERROR, safe.error);
    }

    // https://www.unlocktheinbox.com/dkim-key-length-statistics/ and https://docs.aws.amazon.com/ses/latest/DeveloperGuide/send-email-authentication-dkim-easy.html for key size
    if (!safe.child_process.execSync('openssl genrsa -out ' + dkimPrivateKeyFile + ' 1024')) return new BoxError(BoxError.OPENSSL_ERROR, safe.error);
    if (!safe.child_process.execSync('openssl rsa -in ' + dkimPrivateKeyFile + ' -out ' + dkimPublicKeyFile + ' -pubout -outform PEM')) return new BoxError(BoxError.OPENSSL_ERROR, safe.error);

    if (!safe.fs.writeFileSync(dkimSelectorFile, mailDomain.dkimSelector, 'utf8')) return new BoxError(BoxError.FS_ERROR, safe.error);

    // if the 'yellowtent' user of OS and the 'cloudron' user of mail container don't match, the keys become inaccessible by mail code
    if (!safe.fs.chmodSync(dkimPrivateKeyFile, 0o644)) return new BoxError(BoxError.FS_ERROR, safe.error);

    return null;
}

function readDkimPublicKeySync(domain) {
    assert.strictEqual(typeof domain, 'string');

    var dkimPath = path.join(paths.MAIL_DATA_DIR, `dkim/${domain}`);
    var dkimPublicKeyFile = path.join(dkimPath, 'public');

    var publicKey = safe.fs.readFileSync(dkimPublicKeyFile, 'utf8');

    if (publicKey === null) {
        debug('Error reading dkim public key.', safe.error);
        return null;
    }

    // remove header, footer and new lines
    publicKey = publicKey.split('\n').slice(1, -2).join('');

    return publicKey;
}

function upsertDnsRecords(domain, mailFqdn, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof mailFqdn, 'string');
    assert.strictEqual(typeof callback, 'function');

    debug(`upsertDnsRecords: updating mail dns records of domain ${domain} and mail fqdn ${mailFqdn}`);

    maildb.get(domain, function (error, mailDomain) {
        if (error) return callback(error);

        error = ensureDkimKeySync(mailDomain);
        if (error) return callback(error);

        if (process.env.BOX_ENV === 'test') return callback();

        var dkimKey = readDkimPublicKeySync(domain);
        if (!dkimKey) return callback(new BoxError(BoxError.FS_ERROR, 'Failed to read dkim public key'));

        // t=s limits the domainkey to this domain and not it's subdomains
        var dkimRecord = { subdomain: `${mailDomain.dkimSelector}._domainkey`, domain: domain, type: 'TXT', values: [ '"v=DKIM1; t=s; p=' + dkimKey + '"' ] };

        var records = [ ];
        records.push(dkimRecord);
        if (mailDomain.enabled) {
            records.push({ subdomain: '_dmarc', domain: domain, type: 'TXT', values: [ '"v=DMARC1; p=reject; pct=100"' ] });
            records.push({ subdomain: '', domain: domain, type: 'MX', values: [ '10 ' + mailFqdn + '.' ] });
        }

        txtRecordsWithSpf(domain, mailFqdn, function (error, txtRecords) {
            if (error) return callback(error);

            if (txtRecords) records.push({ subdomain: '', domain: domain, type: 'TXT', values: txtRecords });

            debug('upsertDnsRecords: will update %j', records);

            async.mapSeries(records, function (record, iteratorCallback) {
                domains.upsertDnsRecords(record.subdomain, record.domain, record.type, record.values, iteratorCallback);
            }, function (error, changeIds) {
                if (error) {
                    debug(`upsertDnsRecords: failed to update: ${error}`);
                    return callback(error);
                }

                debug('upsertDnsRecords: records %j added with changeIds %j', records, changeIds);

                callback(null);
            });
        });
    });
}

function setDnsRecords(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    upsertDnsRecords(domain, settings.mailFqdn(), callback);
}

function onMailFqdnChanged(callback) {
    assert.strictEqual(typeof callback, 'function');

    const mailFqdn = settings.mailFqdn(),
        mailDomain = settings.adminDomain();

    domains.getAll(function (error, allDomains) {
        if (error) return callback(error);

        async.eachOfSeries(allDomains, function (domainObject, idx, iteratorDone) {
            upsertDnsRecords(domainObject.domain, mailFqdn, iteratorDone);
        }, function (error) {
            if (error) return callback(error);

            configureMail(mailFqdn, mailDomain, callback);
        });
    });
}

function onDomainAdded(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    async.series([
        upsertDnsRecords.bind(null, domain, settings.mailFqdn()), // do this first to ensure DKIM keys
        restartMailIfActivated
    ], callback);
}

function onDomainRemoved(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    restartMail(callback);
}

function clearDomains(callback) {
    assert.strictEqual(typeof callback, 'function');

    maildb.clear(function (error) {
        if (error) return callback(error);

        callback();
    });
}

// remove all fields that should never be sent out via REST API
function removePrivateFields(domain) {
    let result = _.pick(domain, 'domain', 'enabled', 'mailFromValidation', 'catchAll', 'relay');
    if (result.relay.provider !== 'cloudron-smtp') {
        if (result.relay.username === result.relay.password) result.relay.username = constants.SECRET_PLACEHOLDER;
        result.relay.password = constants.SECRET_PLACEHOLDER;
    }
    return result;
}

function setMailFromValidation(domain, enabled, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof enabled, 'boolean');
    assert.strictEqual(typeof callback, 'function');

    maildb.update(domain, { mailFromValidation: enabled }, function (error) {
        if (error) return callback(error);

        restartMail(NOOP_CALLBACK); // have to restart mail container since haraka cannot watch symlinked config files (mail.ini)

        callback(null);
    });
}

function setCatchAllAddress(domain, addresses, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert(Array.isArray(addresses));
    assert.strictEqual(typeof callback, 'function');

    maildb.update(domain, { catchAll: addresses }, function (error) {
        if (error) return callback(error);

        restartMail(NOOP_CALLBACK); // have to restart mail container since haraka cannot watch symlinked config files (mail.ini)

        callback(null);
    });
}

function setMailRelay(domain, relay, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof relay, 'object');
    assert.strictEqual(typeof callback, 'function');

    getDomain(domain, function (error, result) {
        if (error) return callback(error);

        // inject current username/password
        if (result.relay.provider === relay.provider) {
            if (relay.username === constants.SECRET_PLACEHOLDER) relay.username = result.relay.username;
            if (relay.password === constants.SECRET_PLACEHOLDER) relay.password = result.relay.password;
        }

        verifyRelay(relay, function (error) {
            if (error) return callback(error);

            maildb.update(domain, { relay: relay }, function (error) {
                if (error) return callback(error);

                restartMail(NOOP_CALLBACK);

                callback(null);
            });
        });
    });
}

function setMailEnabled(domain, enabled, auditSource, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof enabled, 'boolean');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    maildb.update(domain, { enabled: enabled }, function (error) {
        if (error) return callback(error);

        restartMail(NOOP_CALLBACK);

        eventlog.add(enabled ? eventlog.ACTION_MAIL_ENABLED : eventlog.ACTION_MAIL_DISABLED, auditSource, { domain });

        callback(null);
    });
}

function sendTestMail(domain, to, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof to, 'string');
    assert.strictEqual(typeof callback, 'function');

    getDomain(domain, function (error, result) {
        if (error) return callback(error);

        mailer.sendTestMail(result.domain, to, function (error) {
            if (error) return callback(error);

            callback();
        });
    });
}

function listMailboxes(domain, page, perPage, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof page, 'number');
    assert.strictEqual(typeof perPage, 'number');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.listMailboxes(domain, page, perPage, function (error, result) {
        if (error) return callback(error);

        callback(null, result);
    });
}

function removeMailboxes(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.delByDomain(domain, function (error) {
        if (error) return callback(error);

        callback();
    });
}

function getMailbox(name, domain, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.getMailbox(name, domain, function (error, result) {
        if (error) return callback(error);

        callback(null, result);
    });
}

function addMailbox(name, domain, userId, auditSource, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof userId, 'string');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    name = name.toLowerCase();

    var error = validateName(name);
    if (error) return callback(error);

    mailboxdb.addMailbox(name, domain, userId, function (error) {
        if (error) return callback(error);

        eventlog.add(eventlog.ACTION_MAIL_MAILBOX_ADD, auditSource, { name, domain, userId });

        callback(null);
    });
}

function updateMailboxOwner(name, domain, userId, auditSource, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof userId, 'string');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    name = name.toLowerCase();

    getMailbox(name, domain, function (error, result) {
        if (error) return callback(error);

        mailboxdb.updateMailboxOwner(name, domain, userId, function (error) {
            if (error) return callback(error);

            eventlog.add(eventlog.ACTION_MAIL_MAILBOX_UPDATE, auditSource, { name, domain, oldUserId: result.userId, userId });

            callback(null);
        });
    });
}

function removeMailbox(name, domain, auditSource, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.del(name, domain, function (error) {
        if (error) return callback(error);

        eventlog.add(eventlog.ACTION_MAIL_MAILBOX_REMOVE, auditSource, { name, domain });

        callback(null);
    });
}

function getAliases(name, domain, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    getMailbox(name, domain, function (error) {
        if (error) return callback(error);

        mailboxdb.getAliasesForName(name, domain, function (error, aliases) {
            if (error) return callback(error);

            callback(null, aliases);
        });
    });
}

function setAliases(name, domain, aliases, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert(Array.isArray(aliases));
    assert.strictEqual(typeof callback, 'function');

    for (var i = 0; i < aliases.length; i++) {
        let name = aliases[i].name.toLowerCase();
        let domain = aliases[i].domain.toLowerCase();

        let error = validateName(name);
        if (error) return callback(error);

        if (!validator.isEmail(`${name}@${domain}`)) return callback(new BoxError(BoxError.BAD_FIELD, `Invalid email: ${name}@${domain}`));
        aliases[i] = { name, domain };
    }
    mailboxdb.setAliasesForName(name, domain, aliases, function (error) {
        if (error) return callback(error);

        callback(null);
    });
}

function getLists(domain, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.getLists(domain, function (error, result) {
        if (error) return callback(error);

        callback(null, result);
    });
}

function getList(name, domain, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.getList(name, domain, function (error, result) {
        if (error) return callback(error);

        callback(null, result);
    });
}

function addList(name, domain, members, membersOnly, auditSource, callback) {
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof name, 'string');
    assert(Array.isArray(members));
    assert.strictEqual(typeof membersOnly, 'boolean');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    name = name.toLowerCase();

    var error = validateName(name);
    if (error) return callback(error);

    for (var i = 0; i < members.length; i++) {
        if (!validator.isEmail(members[i])) return callback(new BoxError(BoxError.BAD_FIELD, 'Invalid mail member: ' + members[i]));
    }

    mailboxdb.addList(name, domain, members, membersOnly, function (error) {
        if (error) return callback(error);

        eventlog.add(eventlog.ACTION_MAIL_LIST_ADD, auditSource, { name, domain, members, membersOnly });

        callback();
    });
}

function updateList(name, domain, members, membersOnly, auditSource, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert(Array.isArray(members));
    assert.strictEqual(typeof membersOnly, 'boolean');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    name = name.toLowerCase();

    var error = validateName(name);
    if (error) return callback(error);

    for (var i = 0; i < members.length; i++) {
        if (!validator.isEmail(members[i])) return callback(new BoxError(BoxError.BAD_FIELD, 'Invalid email: ' + members[i]));
    }

    getList(name, domain, function (error, result) {
        if (error) return callback(error);

        mailboxdb.updateList(name, domain, members, membersOnly, function (error) {
            if (error) return callback(error);

            eventlog.add(eventlog.ACTION_MAIL_MAILBOX_UPDATE, auditSource, { name, domain, oldMembers: result.members, members, membersOnly });

            callback(null);
        });
    });
}

function removeList(name, domain, auditSource, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof domain, 'string');
    assert.strictEqual(typeof auditSource, 'object');
    assert.strictEqual(typeof callback, 'function');

    mailboxdb.del(name, domain, function (error) {
        if (error) return callback(error);

        eventlog.add(eventlog.ACTION_MAIL_LIST_REMOVE, auditSource, { name, domain });

        callback();
    });
}

// resolves the members of a list. i.e the lists and aliases
function resolveList(listName, listDomain, callback) {
    assert.strictEqual(typeof listName, 'string');
    assert.strictEqual(typeof listDomain, 'string');
    assert.strictEqual(typeof callback, 'function');

    getDomains(function (error, mailDomains) {
        if (error) return callback(error);

        const mailInDomains = mailDomains.filter(function (d) { return d.enabled; }).map(function (d) { return d.domain; }).join(',');

        mailboxdb.getList(listName, listDomain, function (error, list) {
            if (error) return callback(error);

            let result = [], toResolve = list.members.slice(), visited = []; // slice creates a copy of array

            async.whilst(() => toResolve.length != 0, function (iteratorCallback) {
                const toProcess = toResolve.shift();
                const parts = toProcess.split('@');
                const memberName = parts[0].split('+')[0], memberDomain = parts[1];

                if (!mailInDomains.includes(memberDomain)) { result.push(toProcess); return iteratorCallback(); } // external domain

                const member =`${memberName}@${memberDomain}`; // cleaned up without any '+' subaddress
                if (visited.includes(member)) {
                    debug(`resolveList: list ${listName}@${listDomain} has a recursion at member ${member}`);
                    return iteratorCallback();
                }
                visited.push(member);

                mailboxdb.get(memberName, memberDomain, function (error, entry) {
                    if (error && error.reason == BoxError.NOT_FOUND) { result.push(member); return iteratorCallback(); } // let it bounce
                    if (error) return iteratorCallback(error);

                    if (entry.type === mailboxdb.TYPE_MAILBOX) { // concrete mailbox
                        result.push(member);
                    } else if (entry.type === mailboxdb.TYPE_ALIAS) { // resolve aliases
                        toResolve = toResolve.concat(`${entry.aliasName}@${entry.aliasTarget}`);
                    } else { // resolve list members
                        toResolve = toResolve.concat(entry.members);
                    }

                    iteratorCallback();
                });
            }, function (error) {
                callback(error, result, list);
            });
        });
    });
}