Rfc6724 resolver ordering semantics #778

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arturobernalg wants to merge 3 commits into apache:master from arturobernalg:Rfc6724A

+1,487 −0

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arturobernalg commented Jan 9, 2026

Introduce Rfc6724AddressSelectingDnsResolver and unit tests.
Define INTERLEAVE as “no bias” (preserve RFC6724 order); keep ONLY/PREFER behavior unchanged.

arturobernalg requested a review from rschmitt

January 9, 2026 17:54

arturobernalg mentioned this pull request

[HTTPCLIENT-2178] Implement Happy Eyeballs V2 (RFC 8305) #693

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          Add RFC6724-based DNS resolver with configurable family preference.

3a1bd12

Define INTERLEAVE as no-bias and align tests and debug output.

arturobernalg force-pushed the Rfc6724A branch from 0802ffe to 3a1bd12 Compare

January 10, 2026 11:21

rschmitt requested changes

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rschmitt left a comment

Main thing here is that I'd like to see a proper implementation of INTERLEAVE, more unit test coverage, and an example program we can use for manual testing.

...client5/src/test/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolverTest.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/AddressSelectingDnsResolver.java Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/AddressSelectingDnsResolver.java Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/AddressSelectingDnsResolver.java Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/config/ProtocolFamilyPreference.java Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated

+                          InetAddress src = null;
+                          try (final DatagramSocket s = new DatagramSocket()) {
+                              s.connect(dest); // does not send packets; OS picks source addr/if
+                              src = s.getLocalAddress();

Contributor

rschmitt Jan 12, 2026

You probably want to inject a thing here that you can mock for unit testing purposes, e.g. a Function<InetSocketAddress, InetAddress> (or an equivalent that throws IOException).

...client5/src/test/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolverTest.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated Show resolved Hide resolved


          Implement true INTERLEAVE ordering.

f6b6dbb

Add manual gated IT to dump DEFAULT vs INTERLEAVE results.
Expand unit coverage for scope mapping and core RFC comparison rules.

arturobernalg requested a review from rschmitt

January 13, 2026 11:02

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arturobernalg commented Jan 13, 2026

@rschmitt Please do another pass. I think i solve all your remarks

rschmitt reviewed

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httpclient5-testing/src/test/java/org/apache/hc/client5/testing/ManualRfc6724ResolverIT.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/AddressSelectingDnsResolver.java Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/AddressSelectingDnsResolver.java Show resolved Hide resolved

httpclient5/src/main/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolver.java Outdated Show resolved Hide resolved

httpclient5/src/test/java/org/apache/hc/client5/http/examples/Rfc6724ResolverExample.java Outdated

+              import org.apache.hc.client5.http.SystemDefaultDnsResolver;
+              import org.apache.hc.client5.http.config.ProtocolFamilyPreference;
+              public final class Rfc6724ResolverExample {

Contributor

rschmitt Jan 14, 2026

src/hc/client # ./run-example.sh Rfc6724ResolverExample www.amazon.com
Host: www.amazon.com
Preference: DEFAULT
  IPv6 2600:1409:9800:1680:0:0:0:3bd4
  IPv6 2600:1409:9800:168d:0:0:0:3bd4
  IPv4 184.27.192.135

src/hc/client # ./run-example.sh Rfc6724ResolverExample www.amazon.com INTERLEAVE
Host: www.amazon.com
Preference: INTERLEAVE
  IPv6 2600:1409:9800:168d:0:0:0:3bd4
  IPv4 184.27.192.135
  IPv6 2600:1409:9800:1680:0:0:0:3bd4

Neat! I'd be cool if I could see the before-and-after (maybe you could intercept the "before" by wrapping the system default resolver, then passing the wrapper in to the RFC 6724 resolver), but it's not essential.

...client5/src/test/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolverTest.java Outdated Show resolved Hide resolved

...client5/src/test/java/org/apache/hc/client5/http/Rfc6724AddressSelectingDnsResolverTest.java Outdated Show resolved Hide resolved

httpclient5-testing/src/test/java/org/apache/hc/client5/testing/ManualRfc6724ResolverIT.java Outdated Show resolved Hide resolved

Contributor

rschmitt commented Jan 14, 2026

There are some things from my first review that still haven't been addressed. I suggest going through the comments one by one and hitting "Resolve conversation" as you address each one, so you can track what is and isn't done.


          Apply RFC 6724 destination ordering and family preferences to DNS res…

d3d8e07

…ults.

Tighten resolver semantics and filtering for HTTP/TCP connect targets.

Member Author

arturobernalg commented Jan 15, 2026

There are some things from my first review that still haven't been addressed. I suggest going through the comments one by one and hitting "Resolve conversation" as you address each one, so you can track what is and isn't done.

Hi @rschmitt I believe I’ve addressed all your remarks in the latest update.

arturobernalg requested a review from rschmitt

January 15, 2026 19:31

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