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connect.fcrdns.js
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connect.fcrdns.js
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var dns = require('dns'),
net = require('net'),
utils = require('./utils'),
net_utils = require('./net_utils');
exports.register = function () {
var plugin = this;
var load_config = function () {
plugin.cfg = plugin.config.get('connect.fcrdns.ini', {
booleans: [
'-reject.no_rdns',
'-reject.no_fcrdns',
'-reject.invalid_tld',
'-reject.generic_rdns',
]
}, load_config);
};
load_config();
};
exports.hook_lookup_rdns = function (next, connection) {
var plugin = this;
var rip = connection.remote_ip;
if (net_utils.is_rfc1918(rip)) {
connection.results.add(plugin, {skip: "private_ip"});
return next();
}
connection.results.add(plugin, {
fcrdns: [], // PTR host names that resolve to this IP
invalid_tlds: [], // rDNS names with invalid TLDs
other_ips: [], // IPs from names that didn't match
ptr_names: [], // Array of host names from PTR query
ptr_multidomain: false, // Multiple host names in different domains
has_rdns: false, // does IP have PTR records?
ptr_name_has_ips: false, // PTR host has IP address(es)
ptr_name_to_ip: {}, // host names and their IP addresses
});
plugin.refresh_config(connection);
var called_next = 0;
var timer;
var do_next = function (code, msg) {
if (called_next) return;
called_next++;
clearTimeout(timer);
return next(code, msg);
};
// Set-up timer
timer = setTimeout(function () {
connection.results.add(plugin, {err: 'timeout', emit: true});
if (plugin.cfg.reject.no_rdns) {
return do_next(DENYSOFT, 'client [' + rip + '] rDNS lookup timeout');
}
return do_next();
}, (plugin.cfg.main.timeout || 30) * 1000);
dns.reverse(rip, function (err, ptr_names) {
connection.logdebug(plugin, 'rdns lookup: ' + rip);
if (err) return plugin.handle_ptr_error(connection, err, do_next);
connection.results.add(plugin, {ptr_names: ptr_names});
connection.results.add(plugin, {has_rdns: true});
// Fetch A records for each PTR host name
var pending_queries = 0;
var queries_run = false;
var results = {};
for (var i=0; i<ptr_names.length; i++) {
var ptr_domain = ptr_names[i].toLowerCase();
results[ptr_domain] = [];
// Make sure TLD is valid
if (!net_utils.get_organizational_domain(ptr_domain)) {
connection.results.add(plugin, {fail: 'valid_tld(' + ptr_domain +')'});
if (!plugin.cfg.reject.invalid_tld) continue;
if (net_utils.is_rfc1918(rip)) continue;
return do_next(DENY, 'client [' + rip +
'] rejected; invalid TLD in rDNS (' + ptr_domain + ')');
}
queries_run = true;
connection.logdebug(plugin, 'domain: ' + ptr_domain);
pending_queries++;
(function (ptr_domain) { /* BEGIN BLOCK SCOPE */
dns.resolve(ptr_domain, function(err, ips_from_fwd) {
pending_queries--;
if (err) {
plugin.handle_a_error(connection, err, ptr_domain);
}
else {
connection.logdebug(plugin, ptr_domain + ' => ' + ips_from_fwd);
results[ptr_domain] = ips_from_fwd;
}
if (pending_queries > 0) return;
// Got all DNS results
connection.results.add(plugin, {ptr_name_to_ip: results});
return plugin.check_fcrdns(connection, results, do_next);
});
})(ptr_domain); /* END BLOCK SCOPE */
}
// No valid PTR
if (!queries_run || (queries_run && pending_queries === 0)) {
return do_next();
}
});
};
exports.hook_data_post = function (next, connection) {
var plugin = this;
var txn = connection.transaction;
txn.remove_header('X-Haraka-rDNS');
txn.remove_header('X-Haraka-FCrDNS');
txn.remove_header('X-Haraka-rDNS-OtherIPs');
txn.remove_header('X-Haraka-HostID');
var fcrdns = connection.results.get('connect.fcrdns');
if (!fcrdns) {
connection.results.add(plugin, {err: "no fcrdns results!?"});
return next();
}
if (fcrdns.name && fcrdns.name.length) {
txn.add_header('X-Haraka-rDNS', fcrdns.name.join(' '));
}
if (fcrdns.fcrdns && fcrdns.fcrdns.length) {
txn.add_header('X-Haraka-FCrDNS', fcrdns.fcrdns.join(' '));
}
if (fcrdns.other_ips && fcrdns.other_ips.length) {
txn.add_header('X-Haraka-rDNS-OtherIPs', fcrdns.other_ips.join(' '));
}
return next();
};
exports.handle_a_error = function(connection, err, domain) {
var plugin = this;
switch (err.code) {
case 'ENOTFOUND':
case dns.NOTFOUND:
case dns.NXDOMAIN:
connection.results.add(plugin, {fail: 'ptr_valid('+domain+')' });
break;
default:
connection.results.add(plugin, {err: err});
}
};
exports.handle_ptr_error = function(connection, err, do_next) {
var plugin = this;
var rip = connection.remote_ip;
switch (err.code) {
case 'ENOTFOUND':
case dns.NOTFOUND:
case dns.NXDOMAIN:
connection.results.add(plugin, {fail: 'has_rdns', emit: true});
if (plugin.cfg.reject.no_rdns) {
return do_next(DENY, 'client [' + rip + '] rejected; no rDNS');
}
return do_next();
default:
connection.results.add(plugin, {err: err.code});
if (plugin.cfg.reject.no_rdns) {
return do_next(DENYSOFT, 'client [' + rip + '] rDNS lookup error (' + err + ')');
}
return do_next();
}
};
exports.check_fcrdns = function(connection, results, do_next) {
var plugin = this;
for (var fdom in results) { // mail.example.com
if (!fdom) continue;
var org_domain = net_utils.get_organizational_domain(fdom); // example.com
// Multiple domains?
if (last_domain && last_domain !== org_domain) {
connection.results.add(plugin, {ptr_multidomain: true});
}
else {
var last_domain = org_domain;
}
// FCrDNS? PTR -> (A | AAAA) 3. PTR comparison
plugin.ptr_compare(results[fdom], connection, fdom);
connection.results.add(plugin, {ptr_name_has_ips: true});
if (plugin.is_generic_rdns(connection, fdom) &&
plugin.cfg.reject.generic_rdns) {
return do_next(DENY, 'client ' + fdom + ' [' + connection.remote_ip +
'] rejected; generic rDNS, please use your ISPs SMTP relay');
}
}
plugin.log_summary(connection);
plugin.save_auth_results(connection);
var r = connection.results.get('connect.fcrdns');
if (!r.fcrdns.length && plugin.cfg.reject.no_fcrdns) {
return do_next(DENY, 'Sorry, no FCrDNS match found');
}
return do_next();
};
exports.ptr_compare = function (ip_list, connection, domain) {
var plugin = this;
if (!ip_list) return false;
if (!ip_list.length) return false;
if (ip_list.indexOf(connection.remote_ip) !== -1) {
connection.results.add(plugin, {pass: 'fcrdns' });
connection.results.push(plugin, {fcrdns: domain});
return true;
}
if (net_utils.same_ipv4_network(connection.remote_ip, ip_list)) {
connection.results.add(plugin, {pass: 'fcrdns(net)' });
connection.results.push(plugin, {fcrdns: domain});
return true;
}
for (var j=0; j<ip_list.length; j++) {
connection.results.push(plugin, {other_ips: ip_list[j]});
}
return false;
};
exports.save_auth_results = function (connection) {
var r = connection.results.get('connect.fcrdns');
if (!r) return;
if (r.fcrdns && r.fcrdns.length) {
connection.auth_results('iprev=pass');
return true;
}
if (!r.has_rdns) {
connection.auth_results('iprev=permerror');
return false;
}
if (r.err.length) {
connection.auth_results('iprev=temperror');
return false;
}
connection.auth_results('iprev=fail');
return false;
};
exports.is_generic_rdns = function (connection, domain) {
var plugin = this;
// IP in rDNS? (Generic rDNS)
if (!domain) return false;
if (!net_utils.is_ip_in_str(connection.remote_ip, domain)) {
connection.results.add(plugin, {pass: 'is_generic_rdns'});
return false;
}
connection.results.add(plugin, {fail: 'is_generic_rdns'});
var orgDom = net_utils.get_organizational_domain(domain);
var host_part = domain.split('.').slice(0,orgDom.split('.').length+1);
if (/(?:static|business)/.test(host_part)) {
// Allow some obvious generic but static ranges
// EHLO/HELO checks will still catch out hosts that use generic rDNS there
connection.loginfo(this, 'allowing generic static rDNS');
return false;
}
return true;
};
exports.log_summary = function (connection) {
if (!connection) return; // connection went away
var note = connection.results.get('connect.fcrdns');
if (!note) return;
connection.loginfo(this,
['ip=' + connection.remote_ip,
'rdns="' + ((note.ptr_names.length > 2) ? note.ptr_names.slice(0,2).join(',') + '...' : note.ptr_names.join(',')) + '"',
'rdns_len=' + note.ptr_names.length,
'fcrdns="' + ((note.fcrdns.length > 2) ? note.fcrdns.slice(0,2).join(',') + '...' : note.fcrdns.join(',')) + '"',
'fcrdns_len=' + note.fcrdns.length,
'other_ips_len=' + note.other_ips.length,
'invalid_tlds=' + note.invalid_tlds.length,
'generic_rdns=' + ((note.ptr_name_has_ips) ? 'true' : 'false'),
].join(' '));
};
exports.refresh_config = function (connection) {
var plugin = this;
// allow rdns_acccess whitelist to override
if (connection.notes.rdns_access && connection.notes.rdns_access === 'white') {
plugin.cfg.reject.no_rdns = 0;
plugin.cfg.reject.invalid_tld = 0;
plugin.cfg.reject.generic_rdns = 0;
}
return plugin.cfg;
};