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dns: fix uv_timer_start usage #39723

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16 changes: 14 additions & 2 deletions src/cares_wrap.cc
Original file line number Diff line number Diff line change
Expand Up @@ -748,8 +748,20 @@ void ChannelWrap::StartTimer() {
}
int timeout = timeout_;
if (timeout == 0) timeout = 1;
if (timeout < 0 || timeout > 1000) timeout = 1000;
uv_timer_start(timer_handle_, AresTimeout, timeout, timeout);
/* -1 implies the default c-ares value, that is 5000, thus checking each
* second */
if (timeout <= -1) timeout = 1000;
if (timeout >= 1000) {
int thousands = (timeout / 1000) * 1000;
/* Pure seconds should be checked every second (for example 1000, 2000,
* 5000) */
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if (timeout - thousands == 0) timeout = 1000;
/* If it's not just seconds (for example 1200, 1050, 2500) check for an
* entire 100ms */
else
timeout = 100;
}
uv_timer_start(timer_handle_, AresTimeout, 0, timeout);
}

void ChannelWrap::CloseTimer() {
Expand Down
80 changes: 80 additions & 0 deletions test/parallel/test-dns-channel-tries.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,80 @@
'use strict';
const common = require('../common');
const assert = require('assert');
const dgram = require('dgram');
const dns = require('dns');

const TRIES = 1;
const IMPRECISION_MS = 500;

// Tests for dns.Resolver option `tries`.
// This will roughly test if a single try fails after the set `timeout`.

for (const ctor of [dns.Resolver, dns.promises.Resolver]) {
for (const tries of [null, true, false, '', '2']) {
assert.throws(() => new ctor({ tries }), {
code: 'ERR_INVALID_ARG_TYPE',
name: 'TypeError',
});
}

for (const tries of [-2, 0, 4.2, 2 ** 31]) {
assert.throws(() => new ctor({ tries }), {
code: 'ERR_OUT_OF_RANGE',
name: 'RangeError',
});
}

for (const tries of [2, 1, 5]) new ctor({ tries });
}

for (let timeout of [-1, 1000, 1500, 50]) {
const server = dgram.createSocket('udp4');
server.bind(0, '127.0.0.1', common.mustCall(() => {
const resolver = new dns.Resolver({ tries: TRIES, timeout });
resolver.setServers([`127.0.0.1:${server.address().port}`]);

const timeStart = performance.now();
resolver.resolve4('nodejs.org', common.mustCall((err) => {
assert.throws(() => { throw err; }, {
code: 'ETIMEOUT',
name: 'Error',
});
const timeEnd = performance.now();

// c-ares default (-1): 5000ms
if (timeout === -1) timeout = 5000;

// Adding 500ms due to imprecisions
const elapsedMs = (timeEnd - timeStart);
assert(elapsedMs <= timeout + IMPRECISION_MS, `The expected timeout did not occur. Expecting: ${timeout + IMPRECISION_MS} But got: ${elapsedMs}`);

server.close();
}));
}));
}

for (let timeout of [-1, 1000, 1500, 50]) {
const server = dgram.createSocket('udp4');
server.bind(0, '127.0.0.1', common.mustCall(() => {
const resolver = new dns.promises.Resolver({ tries: TRIES, timeout });
resolver.setServers([`127.0.0.1:${server.address().port}`]);
const timeStart = performance.now();
resolver.resolve4('nodejs.org').catch(common.mustCall((err) => {
assert.throws(() => { throw err; }, {
code: 'ETIMEOUT',
name: 'Error',
});
const timeEnd = performance.now();

// c-ares default (-1): 5000ms
if (timeout === -1) timeout = 5000;

// Adding 500ms due to imprecisions
const elapsedMs = (timeEnd - timeStart);
assert(elapsedMs <= timeout + IMPRECISION_MS, `The expected timeout did not occur. Expecting: ${timeout + IMPRECISION_MS} But got: ${elapsedMs}`);

server.close();
}));
}));
}