Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 | 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 30x 30x 30x 30x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 22x 1x 1x 21x 21x 21x 21x 22x 32x 32x 1x 1x 31x 31x 32x 191x 7x 7x 191x 184x 184x 191x 31x 32x 1x 1x 30x 30x 32x 10x 10x 32x 19x 19x 22x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 30x 1x 1x 29x 29x 29x 29x 29x 30x 29x 29x 29x 30x 30x 30x 30x 1x 1x 1x 1x 29x 29x 30x 1x 1x 29x 29x 36x 1x 1x 1x 36x 1x 1x 29x 29x 29x 30x 26x 26x 29x 29x 26x 26x 26x 26x 26x 1x 1x 25x 25x 25x 26x 2x 2x 2x 23x 23x 26x 14x 14x 14x 14x 14x 14x 122x 122x 109x 109x 122x 1x 1x 1x 108x 108x 108x 108x 14x 14x 14x 12x 12x 12x 12x 12x 12x 14x 104x 104x 104x 12x 12x 12x 26x 9x 9x 1x 1x 8x 8x 9x 26x 26x 26x 26x 26x 29x 19x 19x 19x 19x 19x 19x 19x 19x 19x 19x 1x 1x 1x 19x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 2x 16x 16x 16x 16x 16x 16x 16x 16x 16x 16x 19x 178x 178x 178x 1x 1x 177x 177x 178x 1x 1x 176x 176x 176x 178x 178x 173x 178x 4x 4x 172x 172x 172x 178x 14x 14x 172x 172x 172x 172x 172x 178x 16x 16x 13x 9x 9x 2x 2x 7x 7x 13x 1x 1x 3x 16x 16x 16x 16x 120x 120x 1x 1x 119x 16x 16x 5x 5x 5x 16x 167x 167x 167x 16x 16x 16x 29x 10x 10x 10x 10x 9x 9x 10x 1x 1x 1x 1x 10x 29x 30x 30x 1x 1x | /*!
* Copyright (c) 2026 The Triauth Authors (https://www.triauth.org/)
*
* 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.
*
* SPDX-License-Identifier: Apache-2.0
*/
import { Base } from './base.js';
import { Helpers } from '../helpers.js';
import { LIMITS } from '../protocol.js';
/**
* A base class for DNS resolvers based on JSON API for DNS over HTTPS (DoH).
*
* It provides a basic implementation of the `resolve` method that uses the JSON API endpoint URL which is expected
* to be set by child classes through the `super(endpointUrl, options={})` call in their respective constructors.
*
* @class
* @memberof Triauth.Resolvers
*
* @see A comprehensive list of public DoH servers is available on
* {@link https://github.com/curl/curl/wiki/DNS-over-HTTPS#publicly-available-servers}.
* Some of them may offer JSON API that allows cross-origin requests.
*/
export class DnsJson extends Base {
/**
* @param url {string} - A base URL of the DoH API endpoint
* @param [options={}] {object}
* @param [options.skipPadding] {boolean} - Set to true if you want to omit using random padding in the fetch url.
* Random padding helps to prevent side-channel privacy attacks based on statistical analysis of the HTTPS payload.
* @param [options.retries] {number} - How many times to retry if name resolution fails. Defaults to 0.
* @param [options.retryDelay] {number} - If failure may be recoverable with time, how long to wait between retries in ms. Defaults to 150.
* @param [options.timeout] {number} - How long to wait before aborting the HTTP fetch request. Defaults to null.
* Requires the runtime to provide `AbortController`; where it does not (e.g. nginx/njs),
* the fetch implementation's own timeout applies instead.
* @param [options.signal] {AbortSignal} - An optional AbortSignal that can be used to abort HTTP fetch requests (requires `AbortController`).
* @param [options.fetch] {Function} - A fetch implementation to use instead of the global `fetch`. Lets constrained runtimes
* inject their own client (e.g. `ngx.fetch` under nginx/njs). Defaults to the global `fetch`.
* @param [options.normalizeTxtRecords] {boolean} - Set to true to convert presentation-form TXT data — each 255-octet character-string wrapped
* in double-quotes, e.g. `"part1" "part2"` — into the record's logical content: the character-string
* contents concatenated in order with no separator (some DoH providers return presentation form).
* @param [options.decodeTxtRecords] {boolean} - Set to true to decode RFC 1035 presentation-format escapes in TXT records - `\NNN` (exactly three
* decimal digits) into that octet, `\X` into X literally — and reinterpret the result as utf-8
* (some DoH providers escape non-printable ASCII). A record carrying a malformed escape
* (`\NNN` above 255, fewer than three digits, a bare trailing backslash) is ignored as a whole.
*/
constructor(url, options = {}) {
super();
this.url = url;
this.options = options;
}
/**
* Converts a TXT record's presentation form into its logical content.
*
* DoH JSON providers that emit presentation form wrap each 255-octet character-string in
* double-quotes and separate consecutive strings with whitespace (`"part1" "part2"`),
* escaping a literal quote as `\"` and a literal backslash as `\\` inside a string.
* The record's logical content is the in-order, no-separator concatenation of the
* character-string contents. Because `\"`, `\\` and decimal `\NNN` escapes all live at the
* same level of the presentation grammar, they must be decoded in a single pass: with
* `keepEscapes` set, `\"` and `\\` sequences are kept verbatim in the output (they still
* delimit correctly) so that the decodeTxtRecords stage decodes every escape at once;
* without it, they decode to their literal characters here.
*
* Data that does not start with a double-quote is already logical content and is returned
* unchanged. Data that starts like presentation form but does not parse as a sequence of
* quoted strings (e.g., an unterminated quote) is returned unchanged, so downstream record
* parsing rejects it instead of consuming a half-normalized value.
*
* @param data {string} - The `Answer[].data` field of a TXT answer.
* @param [keepEscapes=false] {boolean} - Set to true to keep `\"`/`\\` escape sequences verbatim
* in the output, for a subsequent single-pass escape decode.
* @returns {string} The logical record content.
*/
static normalizeTxtData(data, keepEscapes = false) {
if (data.length < 2 || data[0] !== '"') {
return data;
}
let content = '';
let i = 0;
while (i < data.length) {
// Each pass consumes one double-quoted character-string, then any inter-string whitespace
if (data[i] !== '"') {
return data;
}
i++;
for (; i < data.length && data[i] !== '"'; i++) {
if (data[i] === '\\' && (data[i + 1] === '"' || data[i + 1] === '\\')) {
content += keepEscapes ? data[i] + data[i + 1] : data[i + 1];
i++;
} else {
content += data[i];
}
}
if (i >= data.length) {
return data;
}
i++;
while (i < data.length && (data[i] === ' ' || data[i] === '\t')) {
i++;
}
}
return content;
}
/**
* Queries the DNS for resource records of a given type that are stored under a given domainName.
*
* @param domainName {string} - A domain name to query the DNS for. For example "example.com".
* @param type {string} - A type of DNS resource record to look for. For example "TXT", or "A".
* @param [options={}] {object} - Overrides for the options passed to the constructor that will be effective during this function call.
* @param [config={}] {object} - Optional overrides for the global Triauth.config settings
*
* @returns {Promise.<Array.<{value:string, ttl:(number|undefined), dnssec:(boolean|undefined)}>>} A promise that resolves to the array of retrieved DNS resource records in {value, ttl, dnssec} format;
* `ttl` and `dnssec` carry the provider's `TTL` and `AD` fields, and stay undefined where the provider omits them.
*/
resolve(domainName, type, options={}, config={}) {
config = Helpers.mergeConfig(config);
options = Object.assign({
retries: 0,
retryDelay: 150,
skipPadding: false,
timeout: null,
signal: null,
fetch: null
}, this.options, options);
// Ensure type is upper-case
type = String(type).toUpperCase();
return new Promise((resolve, reject) => {
// Browsers and Node expose a global `fetch`; constrained runtimes may inject one through options.fetch.
const fetchImpl = options.fetch || (typeof fetch !== 'undefined' ? fetch : undefined);
if (typeof fetchImpl !== 'function') {
return reject(new Error('No fetch implementation available; pass options.fetch'));
}
let fetchUrl = `${this.url}?name=${encodeURIComponent(domainName)}&type=${encodeURIComponent(type)}`;
// Use random padding to limit the scope for side-channel privacy attacks that use the packet sizes of HTTPS GET requests.
// Uses crypto.getRandomValues so the padding cannot be predicted from a known-plaintext leak.
if (!options.skipPadding) {
const chars = 'abcdefghijklmnopqrstuvwxyz';
fetchUrl += "&random_padding=";
const needed = (50 - (fetchUrl.length % 50)) % 50;
if (needed > 0) {
const rnd = new Uint8Array(needed);
crypto.getRandomValues(rnd);
for (let i = 0; i < needed; i++) {
fetchUrl += chars[rnd[i] % chars.length];
}
}
}
// Prepare fetch abort controller for timeout support and abort signal propagation
// but only if the runtime implements AbortController (e.g., runtimes with custom fetch implementations may be missing it)
const abortController = typeof AbortController !== 'undefined' ? new AbortController() : null;
let timeoutHandle = null;
if (abortController && options.timeout) {
timeoutHandle = setTimeout(() => {
abortController.abort(new Error('Resolver timeout'));
}, options.timeout);
}
const onAbort = () => abortController.abort(new Error('Abort signal received'));
if (abortController && options.signal) {
options.signal.addEventListener('abort', onAbort);
}
const cleanup = () => {
if (timeoutHandle !== null) {
clearTimeout(timeoutHandle);
timeoutHandle = null;
}
if (abortController && options.signal) {
options.signal.removeEventListener('abort', onAbort);
}
};
const fetchOptions = { headers: { 'Accept': 'application/dns-json' } };
if (abortController) {
fetchOptions.signal = abortController.signal;
}
return fetchImpl(fetchUrl, fetchOptions).then(async (response) => {
// cleanup() is intentionally deferred to the `finally` below so the
// per-request timeout stays armed across the entire body read,
// bounding slow-body delivery (server sends headers fast, then dribbles bytes).
try {
if (!response.ok) {
throw new Error(`DoH request failed with HTTP ${response.status}`);
}
// Bail early when the server *declares* an over-limit body.
const declared = parseInt(response.headers.get('content-length'), 10);
if (Number.isFinite(declared) && declared > LIMITS.jsonMaxBytesize) {
abortController?.abort(new Error('DoH response exceeds size limit'));
throw new Error('DoH response exceeds size limit (Content-Length)');
}
// Prefer incremental streaming when supported; fall back to .text() if not
if (response.body && typeof response.body.getReader === 'function') {
const reader = response.body.getReader();
const chunks = [];
let received = 0;
try {
for (;;) {
const { value, done } = await reader.read();
if (done) break;
// Check BEFORE accumulating the over-limit chunk so we never hold it.
if (received + value.byteLength > LIMITS.jsonMaxBytesize) {
abortController?.abort(new Error('DoH response exceeds size limit'));
throw new Error('DoH response exceeds size limit');
}
received += value.byteLength;
chunks.push(value);
}
} finally {
try { reader.releaseLock(); } catch { /* reader may already be errored */ }
}
// Assemble and decode once — multi-byte sequences may span chunk boundaries.
// Strict: a body that is not well-formed UTF-8 rejects the whole response
// (propagates to the retry/reject path below, like any transport failure).
const bytes = new Uint8Array(received);
let offset = 0;
for (const chunk of chunks) {
bytes.set(chunk, offset);
offset += chunk.byteLength;
}
return Helpers.utf8BytesToString(bytes);
} else if (typeof response.text === 'function') {
const text = await response.text();
if (Helpers.byteSize(text) > LIMITS.jsonMaxBytesize) {
throw new Error('DoH response exceeds size limit');
}
return text;
} else {
throw new Error('DoH response has no readable body');
}
} finally {
cleanup();
}
}).then(async(text) => {
let json;
try {
json = Helpers.safeParseJson(text);
} catch (err) {
return reject(err);
}
// Check for error response status code(s), and act appropriately
// @see DNS status codes - http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6
// for NXDOMAIN return empty array
if (json['Status'] === 3) {
return resolve([]);
// for other errors, retry and if still error, fail
} else if (json['Status'] !== 0) {
if (options.retries <= 0) {
return reject(new Error(`DoH response carries DNS status ${json['Status']}`));
} else {
options.retries -= 1;
if (options.retryDelay) {
await new Promise((resolve) => {
return setTimeout(resolve, options.retryDelay);
});
}
return this.resolve(domainName, type, options, config).then(resolve, reject);
}
}
// The status code is 0 - all fine, continue to extract and parse the answer
const retval = [];
const dnsRecordTypes = {
'TXT': 16,
'A': 1,
'AAAA': 28,
'CNAME': 5
}
for (const a of (json['Answer'] || [])) {
// Ensure the response is for the correct domain
if (a['name'] !== domainName && a['name'] !== domainName + '.') {
continue;
}
// Ensure the response has the requested record type
if (dnsRecordTypes[type.toUpperCase()] !== a['type']) {
continue;
}
// Ensure the response has fields of expected types
if (
typeof a['data'] !== 'string' ||
(!Number.isInteger(a['TTL']) || a['TTL'] < 0) ||
typeof json['AD'] !== 'boolean'
) {
continue;
}
// Convert presentation-form TXT data into the record's logical content if normalizeTxtRecords is set;
// when the decode stage below will run, escapes stay verbatim so it can decode them in one pass
if (a['type'] === 16 && options.normalizeTxtRecords) {
a['data'] = DnsJson.normalizeTxtData(a['data'], options.decodeTxtRecords);
}
// Decode escaped chars: one left-to-right pass over the RFC 1035 escape grammar —
// `\DDD` (exactly three digits, one octet) yields that byte, `\X` yields X literally,
// and anything else (`\DDD` above 255, fewer than three digits, a bare trailing
// backslash) rejects the record as a whole rather than guessing
if (a['type'] === 16 && options.decodeTxtRecords) {
try {
const bytes = a['data'].replace(/\\(\d{3})|\\(\D)?/g, (m, ddd, ch) => {
if (ddd !== undefined) {
const code = parseInt(ddd, 10);
if (code > 255) {
throw new Error('Invalid \\DDD escape in a TXT record');
}
return String.fromCharCode(code);
}
if (ch === undefined) {
throw new Error('Truncated escape in a TXT record');
}
return ch;
});
// One-char-per-octet contract: a char above U+00FF is not an octet, so it rejects
// the record rather than wrapping mod-256 into an unrelated byte
a['data'] = Helpers.utf8BytesToString(Uint8Array.from(bytes, (c) => {
const byte = c.charCodeAt(0);
if (byte > 255) {
throw new Error('Non-octet character in a TXT record escape decode');
}
return byte;
}));
} catch (err) {
config.logger?.debug?.(`DNS TXT record could not be decoded`, {cause:err});
continue;
}
}
retval.push({value: a['data'], ttl: a['TTL'], dnssec: json['AD']});
}
return resolve(retval);
}).catch((err) => {
cleanup();
config.logger?.debug?.(err);
if (options.signal?.aborted || options.retries <= 0) {
return reject(err);
} else {
options.retries -= 1;
return this.resolve(domainName, type, options, config).then(resolve, reject);
}
});
});
}
}
|