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fix: filter out duplicate dns results MONGOSH-2027 #209

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Merged
merged 4 commits into from
Feb 27, 2025
Merged

fix: filter out duplicate dns results MONGOSH-2027 #209

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e3c515e
fix: filter out duplicate dns results
nirinchev Feb 26, 2025
0204e18
address comments
nirinchev Feb 27, 2025
0c5bd24
Rearrange some code
nirinchev Feb 27, 2025
9569f75
fix lint
nirinchev Feb 27, 2025
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61 changes: 61 additions & 0 deletions src/rfc-8252-http-server.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ import type { SinonSandbox } from 'sinon';
import sinon from 'sinon';
import { promisify } from 'util';
import { randomBytes } from 'crypto';
import { promises as dns } from 'dns';

// node-fetch@3 is ESM-only...
// eslint-disable-next-line @typescript-eslint/consistent-type-imports
Expand Down Expand Up @@ -485,4 +486,64 @@ describe('RFC8252HTTPServer', function () {
});
});
});

context('with dns duplicates', function () {
let dnsLookupStub: sinon.SinonStub;
const _getAllInterfaces = RFC8252HTTPServer['_getAllInterfaces'];

this.beforeEach(function () {
dnsLookupStub = sinon.stub(dns, 'lookup');
});

this.afterEach(function () {
sinon.restore();
});

it('only filters exact duplicates', async function () {
dnsLookupStub.resolves([
{ address: '127.0.0.1', family: 4 },
{ address: '127.0.0.1', family: 4 },
{ address: '[::1]', family: 6 },
{ address: '[::1]', family: 6 },
]);

const interfaces = await _getAllInterfaces('localhost');

expect(interfaces).to.have.lengthOf(2);
expect(interfaces[0].address).to.equal('127.0.0.1');
expect(interfaces[1].address).to.equal('[::1]');
expect(interfaces[0].family).to.equal(4);
expect(interfaces[1].family).to.equal(6);
});

it('keeps same addresses, different family', async function () {
dnsLookupStub.resolves([
{ address: '127.0.0.1', family: 4 },
{ address: '127.0.0.1', family: 6 },
]);

const interfaces = await _getAllInterfaces('localhost');

expect(interfaces).to.have.lengthOf(2);
expect(interfaces[0].address).to.equal('127.0.0.1');
expect(interfaces[1].address).to.equal('127.0.0.1');
expect(interfaces[0].family).to.equal(4);
expect(interfaces[1].family).to.equal(6);
});

it('keeps same familes, different address', async function () {
dnsLookupStub.resolves([
{ address: '127.0.0.1', family: 4 },
{ address: '192.168.1.15', family: 4 },
]);

const interfaces = await _getAllInterfaces('localhost');

expect(interfaces).to.have.lengthOf(2);
expect(interfaces[0].address).to.equal('127.0.0.1');
expect(interfaces[1].address).to.equal('192.168.1.15');
expect(interfaces[0].family).to.equal(4);
expect(interfaces[1].family).to.equal(4);
});
});
});
30 changes: 23 additions & 7 deletions src/rfc-8252-http-server.ts
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Expand Up @@ -272,6 +272,25 @@ export class RFC8252HTTPServer {
});
};

private static async _getAllInterfaces(
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optional suggestions: Feels a bit silly to mark this private and then access it as if it weren't private, no? It's not exported from the package anyway, don't be shy to mark this public to make it a bit more obvious that it's tested directly

And while you're at it, you might as well pass in dns.lookup as an argument instead of mocking it in that case?

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I was debating with myself whether I want to make it public or if I want to instead call .listen() and then inspect the logs to see what interfaces were discovered. I feel a bit iffy about exposing methods publicly only for the sake of testing, but perhaps that's a bit more acceptable in the JS world 😅

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If that feels iffy, I think you could also just export it as a separate method, it's fairly standalone and not really tied to the rest of the class semantically 🙂

hostname: string
): Promise<{ address: string; family: number }[]> {
const dnsResults = await dns.lookup(hostname, {
all: true,
hints: ADDRCONFIG,
});

return dnsResults
.filter(
(dns, index, arr) =>
arr.findIndex(
(otherDns) =>
dns.address === otherDns.address && dns.family === otherDns.family
) === index
)
.map(({ address, family }) => ({ address, family }));
}

/**
* Add a redirect from a local URL served on the server to an external URL.
*/
Expand Down Expand Up @@ -368,14 +387,11 @@ export class RFC8252HTTPServer {
// to do what Node.js does by default when only a host is provided,
// namely listening on all interfaces.
let hostname = this.redirectUrl.hostname;
if (hostname.startsWith('[') && hostname.endsWith(']'))
if (hostname.startsWith('[') && hostname.endsWith(']')) {
hostname = hostname.slice(1, -1);
const dnsResults = (
await dns.lookup(hostname, {
all: true,
hints: ADDRCONFIG,
})
).map(({ address, family }) => ({ address, family }));
}

const dnsResults = await RFC8252HTTPServer._getAllInterfaces(hostname);

this.logger.emit('mongodb-oidc-plugin:local-listen-resolved-hostname', {
url: this.redirectUrl.toString(),
Expand Down
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