File size: 15,660 Bytes
f8f5b35 10852fa f8f5b35 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 |
"use strict";
/*
* Copyright 2019 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.DEFAULT_PORT = void 0;
exports.setup = setup;
const resolver_1 = require("./resolver");
const dns_1 = require("dns");
const service_config_1 = require("./service-config");
const constants_1 = require("./constants");
const metadata_1 = require("./metadata");
const logging = require("./logging");
const constants_2 = require("./constants");
const uri_parser_1 = require("./uri-parser");
const net_1 = require("net");
const backoff_timeout_1 = require("./backoff-timeout");
const environment_1 = require("./environment");
const TRACER_NAME = 'dns_resolver';
function trace(text) {
logging.trace(constants_2.LogVerbosity.DEBUG, TRACER_NAME, text);
}
/**
* The default TCP port to connect to if not explicitly specified in the target.
*/
exports.DEFAULT_PORT = 443;
const DEFAULT_MIN_TIME_BETWEEN_RESOLUTIONS_MS = 30000;
/**
* Resolver implementation that handles DNS names and IP addresses.
*/
class DnsResolver {
constructor(target, listener, channelOptions) {
var _a, _b, _c;
this.target = target;
this.listener = listener;
this.pendingLookupPromise = null;
this.pendingTxtPromise = null;
this.latestLookupResult = null;
this.latestServiceConfig = null;
this.latestServiceConfigError = null;
this.continueResolving = false;
this.isNextResolutionTimerRunning = false;
this.isServiceConfigEnabled = true;
this.returnedIpResult = false;
this.alternativeResolver = new dns_1.promises.Resolver();
trace('Resolver constructed for target ' + (0, uri_parser_1.uriToString)(target));
if (target.authority) {
this.alternativeResolver.setServers([target.authority]);
}
const hostPort = (0, uri_parser_1.splitHostPort)(target.path);
if (hostPort === null) {
this.ipResult = null;
this.dnsHostname = null;
this.port = null;
}
else {
if ((0, net_1.isIPv4)(hostPort.host) || (0, net_1.isIPv6)(hostPort.host)) {
this.ipResult = [
{
addresses: [
{
host: hostPort.host,
port: (_a = hostPort.port) !== null && _a !== void 0 ? _a : exports.DEFAULT_PORT,
},
],
},
];
this.dnsHostname = null;
this.port = null;
}
else {
this.ipResult = null;
this.dnsHostname = hostPort.host;
this.port = (_b = hostPort.port) !== null && _b !== void 0 ? _b : exports.DEFAULT_PORT;
}
}
this.percentage = Math.random() * 100;
if (channelOptions['grpc.service_config_disable_resolution'] === 1) {
this.isServiceConfigEnabled = false;
}
this.defaultResolutionError = {
code: constants_1.Status.UNAVAILABLE,
details: `Name resolution failed for target ${(0, uri_parser_1.uriToString)(this.target)}`,
metadata: new metadata_1.Metadata(),
};
const backoffOptions = {
initialDelay: channelOptions['grpc.initial_reconnect_backoff_ms'],
maxDelay: channelOptions['grpc.max_reconnect_backoff_ms'],
};
this.backoff = new backoff_timeout_1.BackoffTimeout(() => {
if (this.continueResolving) {
this.startResolutionWithBackoff();
}
}, backoffOptions);
this.backoff.unref();
this.minTimeBetweenResolutionsMs =
(_c = channelOptions['grpc.dns_min_time_between_resolutions_ms']) !== null && _c !== void 0 ? _c : DEFAULT_MIN_TIME_BETWEEN_RESOLUTIONS_MS;
this.nextResolutionTimer = setTimeout(() => { }, 0);
clearTimeout(this.nextResolutionTimer);
}
/**
* If the target is an IP address, just provide that address as a result.
* Otherwise, initiate A, AAAA, and TXT lookups
*/
startResolution() {
if (this.ipResult !== null) {
if (!this.returnedIpResult) {
trace('Returning IP address for target ' + (0, uri_parser_1.uriToString)(this.target));
setImmediate(() => {
this.listener.onSuccessfulResolution(this.ipResult, null, null, null, {});
});
this.returnedIpResult = true;
}
this.backoff.stop();
this.backoff.reset();
this.stopNextResolutionTimer();
return;
}
if (this.dnsHostname === null) {
trace('Failed to parse DNS address ' + (0, uri_parser_1.uriToString)(this.target));
setImmediate(() => {
this.listener.onError({
code: constants_1.Status.UNAVAILABLE,
details: `Failed to parse DNS address ${(0, uri_parser_1.uriToString)(this.target)}`,
metadata: new metadata_1.Metadata(),
});
});
this.stopNextResolutionTimer();
}
else {
if (this.pendingLookupPromise !== null) {
return;
}
trace('Looking up DNS hostname ' + this.dnsHostname);
/* We clear out latestLookupResult here to ensure that it contains the
* latest result since the last time we started resolving. That way, the
* TXT resolution handler can use it, but only if it finishes second. We
* don't clear out any previous service config results because it's
* better to use a service config that's slightly out of date than to
* revert to an effectively blank one. */
this.latestLookupResult = null;
const hostname = this.dnsHostname;
this.pendingLookupPromise = this.lookup(hostname);
this.pendingLookupPromise.then(addressList => {
if (this.pendingLookupPromise === null) {
return;
}
this.pendingLookupPromise = null;
this.backoff.reset();
this.backoff.stop();
this.latestLookupResult = addressList.map(address => ({
addresses: [address],
}));
const allAddressesString = '[' +
addressList.map(addr => addr.host + ':' + addr.port).join(',') +
']';
trace('Resolved addresses for target ' +
(0, uri_parser_1.uriToString)(this.target) +
': ' +
allAddressesString);
if (this.latestLookupResult.length === 0) {
this.listener.onError(this.defaultResolutionError);
return;
}
/* If the TXT lookup has not yet finished, both of the last two
* arguments will be null, which is the equivalent of getting an
* empty TXT response. When the TXT lookup does finish, its handler
* can update the service config by using the same address list */
this.listener.onSuccessfulResolution(this.latestLookupResult, this.latestServiceConfig, this.latestServiceConfigError, null, {});
}, err => {
if (this.pendingLookupPromise === null) {
return;
}
trace('Resolution error for target ' +
(0, uri_parser_1.uriToString)(this.target) +
': ' +
err.message);
this.pendingLookupPromise = null;
this.stopNextResolutionTimer();
this.listener.onError(this.defaultResolutionError);
});
/* If there already is a still-pending TXT resolution, we can just use
* that result when it comes in */
if (this.isServiceConfigEnabled && this.pendingTxtPromise === null) {
/* We handle the TXT query promise differently than the others because
* the name resolution attempt as a whole is a success even if the TXT
* lookup fails */
this.pendingTxtPromise = this.resolveTxt(hostname);
this.pendingTxtPromise.then(txtRecord => {
if (this.pendingTxtPromise === null) {
return;
}
this.pendingTxtPromise = null;
try {
this.latestServiceConfig = (0, service_config_1.extractAndSelectServiceConfig)(txtRecord, this.percentage);
}
catch (err) {
this.latestServiceConfigError = {
code: constants_1.Status.UNAVAILABLE,
details: `Parsing service config failed with error ${err.message}`,
metadata: new metadata_1.Metadata(),
};
}
if (this.latestLookupResult !== null) {
/* We rely here on the assumption that calling this function with
* identical parameters will be essentialy idempotent, and calling
* it with the same address list and a different service config
* should result in a fast and seamless switchover. */
this.listener.onSuccessfulResolution(this.latestLookupResult, this.latestServiceConfig, this.latestServiceConfigError, null, {});
}
}, err => {
/* If TXT lookup fails we should do nothing, which means that we
* continue to use the result of the most recent successful lookup,
* or the default null config object if there has never been a
* successful lookup. We do not set the latestServiceConfigError
* here because that is specifically used for response validation
* errors. We still need to handle this error so that it does not
* bubble up as an unhandled promise rejection. */
});
}
}
}
async lookup(hostname) {
if (environment_1.GRPC_NODE_USE_ALTERNATIVE_RESOLVER) {
trace('Using alternative DNS resolver.');
const records = await Promise.allSettled([
this.alternativeResolver.resolve4(hostname),
this.alternativeResolver.resolve6(hostname),
]);
if (records.every(result => result.status === 'rejected')) {
throw new Error(records[0].reason);
}
return records
.reduce((acc, result) => {
return result.status === 'fulfilled'
? [...acc, ...result.value]
: acc;
}, [])
.map(addr => ({
host: addr,
port: +this.port,
}));
}
/* We lookup both address families here and then split them up later
* because when looking up a single family, dns.lookup outputs an error
* if the name exists but there are no records for that family, and that
* error is indistinguishable from other kinds of errors */
const addressList = await dns_1.promises.lookup(hostname, { all: true });
return addressList.map(addr => ({ host: addr.address, port: +this.port }));
}
async resolveTxt(hostname) {
if (environment_1.GRPC_NODE_USE_ALTERNATIVE_RESOLVER) {
trace('Using alternative DNS resolver.');
return this.alternativeResolver.resolveTxt(hostname);
}
return dns_1.promises.resolveTxt(hostname);
}
startNextResolutionTimer() {
var _a, _b;
clearTimeout(this.nextResolutionTimer);
this.nextResolutionTimer = setTimeout(() => {
this.stopNextResolutionTimer();
if (this.continueResolving) {
this.startResolutionWithBackoff();
}
}, this.minTimeBetweenResolutionsMs);
(_b = (_a = this.nextResolutionTimer).unref) === null || _b === void 0 ? void 0 : _b.call(_a);
this.isNextResolutionTimerRunning = true;
}
stopNextResolutionTimer() {
clearTimeout(this.nextResolutionTimer);
this.isNextResolutionTimerRunning = false;
}
startResolutionWithBackoff() {
if (this.pendingLookupPromise === null) {
this.continueResolving = false;
this.backoff.runOnce();
this.startNextResolutionTimer();
this.startResolution();
}
}
updateResolution() {
/* If there is a pending lookup, just let it finish. Otherwise, if the
* nextResolutionTimer or backoff timer is running, set the
* continueResolving flag to resolve when whichever of those timers
* fires. Otherwise, start resolving immediately. */
if (this.pendingLookupPromise === null) {
if (this.isNextResolutionTimerRunning || this.backoff.isRunning()) {
if (this.isNextResolutionTimerRunning) {
trace('resolution update delayed by "min time between resolutions" rate limit');
}
else {
trace('resolution update delayed by backoff timer until ' +
this.backoff.getEndTime().toISOString());
}
this.continueResolving = true;
}
else {
this.startResolutionWithBackoff();
}
}
}
/**
* Reset the resolver to the same state it had when it was created. In-flight
* DNS requests cannot be cancelled, but they are discarded and their results
* will be ignored.
*/
destroy() {
this.continueResolving = false;
this.backoff.reset();
this.backoff.stop();
this.stopNextResolutionTimer();
this.pendingLookupPromise = null;
this.pendingTxtPromise = null;
this.latestLookupResult = null;
this.latestServiceConfig = null;
this.latestServiceConfigError = null;
this.returnedIpResult = false;
}
/**
* Get the default authority for the given target. For IP targets, that is
* the IP address. For DNS targets, it is the hostname.
* @param target
*/
static getDefaultAuthority(target) {
return target.path;
}
}
/**
* Set up the DNS resolver class by registering it as the handler for the
* "dns:" prefix and as the default resolver.
*/
function setup() {
(0, resolver_1.registerResolver)('dns', DnsResolver);
(0, resolver_1.registerDefaultScheme)('dns');
}
//# sourceMappingURL=resolver-dns.js.map |