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fix(xds): Allow and normalize trailing dot (FQDN) in matchHostName #12644

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Merged
kannanjgithub merged 6 commits into from
Feb 9, 2026
Merged

fix(xds): Allow and normalize trailing dot (FQDN) in matchHostName #12644

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e4a5e49
fix(xds): Allow and normalize trailing dot (FQDN) in matchHostName
PetitBaguette Feb 4, 2026
4adb94d
style(xds): Fix line length in matchHostName_trailingDot test for che…
PetitBaguette Feb 4, 2026
cb2e509
test(xds): Add trailing dot test for findVirtualHostForHostName in Ro…
PetitBaguette Feb 5, 2026
4265498
refactor(xds): Remove unused matchHostName from XdsNameResolver, move…
PetitBaguette Feb 5, 2026
88e63d8
chore(xds): remove unused import
PetitBaguette Feb 5, 2026
da579a1
test(xds): Add invalid input tests for matchHostName in RoutingUtilsTest
PetitBaguette Feb 5, 2026
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13 changes: 11 additions & 2 deletions xds/src/main/java/io/grpc/xds/RoutingUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -92,15 +92,24 @@ static VirtualHost findVirtualHostForHostName(List<VirtualHost> virtualHosts, St
* </ol>
*/
private static boolean matchHostName(String hostName, String pattern) {
checkArgument(hostName.length() != 0 && !hostName.startsWith(".") && !hostName.endsWith("."),
checkArgument(hostName.length() != 0 && !hostName.startsWith("."),
"Invalid host name");
checkArgument(pattern.length() != 0 && !pattern.startsWith(".") && !pattern.endsWith("."),
checkArgument(pattern.length() != 0 && !pattern.startsWith("."),
"Invalid pattern/domain name");

hostName = hostName.toLowerCase(Locale.US);
pattern = pattern.toLowerCase(Locale.US);
// hostName and pattern are now in lower case -- domain names are case-insensitive.

// Strip trailing dot to normalize FQDN (e.g. "example.com.") to a relative form,
// as per RFC 1034 Section 3.1 the two are semantically equivalent.
if (hostName.endsWith(".")) {
hostName = hostName.substring(0, hostName.length() - 1);
}
if (pattern.endsWith(".")) {
pattern = pattern.substring(0, pattern.length() - 1);
}

if (!pattern.contains("*")) {
// Not a wildcard pattern -- hostName and pattern must match exactly.
return hostName.equals(pattern);
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13 changes: 11 additions & 2 deletions xds/src/main/java/io/grpc/xds/XdsNameResolver.java
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Expand Up @@ -354,15 +354,24 @@ private void updateResolutionResult(XdsConfig xdsConfig) {
*/
@VisibleForTesting
static boolean matchHostName(String hostName, String pattern) {
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@kannanjgithub kannanjgithub Feb 5, 2026

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This method is actually unused now for some time. Can you remove it and its calling tests? Instead make unit tests for RoutingUtils which is the actively used code.

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@PetitBaguette PetitBaguette Feb 5, 2026

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I have applied the requested changes.

All CI checks have passed, with the exception of grpc-java-testing-pr (grpc-testing), which indicates that it needs a /gcbrun command from a collaborator.

Please let me know if there are any other points I should address.

checkArgument(hostName.length() != 0 && !hostName.startsWith(".") && !hostName.endsWith("."),
checkArgument(hostName.length() != 0 && !hostName.startsWith("."),
"Invalid host name");
checkArgument(pattern.length() != 0 && !pattern.startsWith(".") && !pattern.endsWith("."),
checkArgument(pattern.length() != 0 && !pattern.startsWith("."),
"Invalid pattern/domain name");

hostName = hostName.toLowerCase(Locale.US);
pattern = pattern.toLowerCase(Locale.US);
// hostName and pattern are now in lower case -- domain names are case-insensitive.

// Strip trailing dot to normalize FQDN (e.g. "example.com.") to a relative form,
// as per RFC 1034 Section 3.1 the two are semantically equivalent.
if (hostName.endsWith(".")) {
hostName = hostName.substring(0, hostName.length() - 1);
}
if (pattern.endsWith(".")) {
pattern = pattern.substring(0, pattern.length() - 1);
}

if (!pattern.contains("*")) {
// Not a wildcard pattern -- hostName and pattern must match exactly.
return hostName.equals(pattern);
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48 changes: 48 additions & 0 deletions xds/src/test/java/io/grpc/xds/RoutingUtilsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,54 @@ public void findVirtualHostForHostName_asteriskMatchAnyDomain() {
.isEqualTo(vHost1);
}

@Test
public void findVirtualHostForHostName_trailingDot() {
// FQDN (trailing dot) is semantically equivalent to the relative form
// per RFC 1034 Section 3.1.
List<Route> routes = Collections.emptyList();
VirtualHost vHost1 = VirtualHost.create("virtualhost01.googleapis.com",
Collections.singletonList("a.googleapis.com"), routes,
ImmutableMap.of());
VirtualHost vHost2 = VirtualHost.create("virtualhost02.googleapis.com",
Collections.singletonList("*.googleapis.com"), routes,
ImmutableMap.of());
VirtualHost vHost3 = VirtualHost.create("virtualhost03.googleapis.com",
Collections.singletonList("*"), routes,
ImmutableMap.of());
List<VirtualHost> virtualHosts = Arrays.asList(vHost1, vHost2, vHost3);

// Trailing dot in hostName, exact match.
assertThat(RoutingUtils.findVirtualHostForHostName(
virtualHosts, "a.googleapis.com.")).isEqualTo(vHost1);
// Trailing dot in hostName, wildcard match.
assertThat(RoutingUtils.findVirtualHostForHostName(
virtualHosts, "b.googleapis.com.")).isEqualTo(vHost2);

// Trailing dot in domain pattern, exact match.
VirtualHost vHost4 = VirtualHost.create("virtualhost04.googleapis.com",
Collections.singletonList("a.googleapis.com."), routes,
ImmutableMap.of());
List<VirtualHost> virtualHosts2 =
Arrays.asList(vHost4, vHost2, vHost3);
assertThat(RoutingUtils.findVirtualHostForHostName(
virtualHosts2, "a.googleapis.com")).isEqualTo(vHost4);

// Trailing dot in both hostName and domain pattern.
assertThat(RoutingUtils.findVirtualHostForHostName(
virtualHosts2, "a.googleapis.com.")).isEqualTo(vHost4);

// Trailing dot in domain pattern, wildcard match.
VirtualHost vHost5 = VirtualHost.create("virtualhost05.googleapis.com",
Collections.singletonList("*.googleapis.com."), routes,
ImmutableMap.of());
List<VirtualHost> virtualHosts3 =
Arrays.asList(vHost5, vHost3);
assertThat(RoutingUtils.findVirtualHostForHostName(
virtualHosts3, "b.googleapis.com")).isEqualTo(vHost5);
assertThat(RoutingUtils.findVirtualHostForHostName(
virtualHosts3, "b.googleapis.com.")).isEqualTo(vHost5);
}

@Test
public void routeMatching_pathOnly() {
Metadata headers = new Metadata();
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23 changes: 23 additions & 0 deletions xds/src/test/java/io/grpc/xds/XdsNameResolverTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2062,6 +2062,29 @@ public void matchHostName_postfixWildCard() {
assertThat(XdsNameResolver.matchHostName("foo-bar", pattern)).isTrue();
}

@Test
public void matchHostName_trailingDot() {
// FQDN (trailing dot) is semantically equivalent to the relative form per RFC 1034 Section 3.1.
assertThat(XdsNameResolver.matchHostName("foo.googleapis.com.", "foo.googleapis.com")).isTrue();
assertThat(XdsNameResolver.matchHostName("foo.googleapis.com", "foo.googleapis.com.")).isTrue();
assertThat(XdsNameResolver.matchHostName("foo.googleapis.com.", "foo.googleapis.com."))
.isTrue();
assertThat(XdsNameResolver.matchHostName("bar.googleapis.com.", "foo.googleapis.com"))
.isFalse();

// Wildcard + trailing dot combinations.
String pattern = "*.foo.googleapis.com";
assertThat(XdsNameResolver.matchHostName("bar.foo.googleapis.com.", pattern)).isTrue();
assertThat(XdsNameResolver.matchHostName("bar.foo.googleapis.com", pattern + ".")).isTrue();
assertThat(XdsNameResolver.matchHostName("bar.foo.googleapis.com.", pattern + ".")).isTrue();
assertThat(XdsNameResolver.matchHostName("foo.googleapis.com.", pattern)).isFalse();

pattern = "foo.*";
assertThat(XdsNameResolver.matchHostName("foo.googleapis.com.", pattern)).isTrue();
assertThat(XdsNameResolver.matchHostName("foo.com.", pattern)).isTrue();
assertThat(XdsNameResolver.matchHostName("bar.googleapis.com.", pattern)).isFalse();
}

@Test
public void resolved_faultAbortInLdsUpdate() {
resolver.start(mockListener);
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