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Require ALPN when forcing HTTP/2 over TLS #631

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Merged
arturobernalg merged 1 commit into from
Feb 22, 2026
Merged

Require ALPN when forcing HTTP/2 over TLS #631

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7 changes: 5 additions & 2 deletions ...rc/main/java/org/apache/hc/core5/http2/impl/nio/ClientHttpProtocolNegotiationStarter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -94,8 +94,11 @@ public HttpConnectionEventHandler createHandler(final ProtocolIOSession ioSessio
ioSession.registerProtocol(ApplicationProtocol.HTTP_2.id, new ClientH2UpgradeHandler(http2StreamHandlerFactory, exceptionCallback));

switch (endpointPolicy) {
case FORCE_HTTP_2:
return new ClientH2PrefaceHandler(ioSession, http2StreamHandlerFactory, false, exceptionCallback);
case FORCE_HTTP_2: {
// In forced HTTP/2 mode, require ALPN negotiation on TLS sessions.
final boolean strictAlpn = ioSession.getTlsDetails() != null;
return new ClientH2PrefaceHandler(ioSession, http2StreamHandlerFactory, strictAlpn, exceptionCallback);
}
case FORCE_HTTP_1:
return new ClientHttp1IOEventHandler(http1StreamHandlerFactory.create(ioSession));
default:
Expand Down
35 changes: 35 additions & 0 deletions ...est/java/org/apache/hc/core5/http2/impl/nio/TestClientHttpProtocolNegotiationStarter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@
import org.apache.hc.core5.http2.ssl.ApplicationProtocol;
import org.apache.hc.core5.reactor.EndpointParameters;
import org.apache.hc.core5.reactor.ProtocolIOSession;
import org.apache.hc.core5.reactor.ssl.TlsDetails;
import org.apache.hc.core5.util.Timeout;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
Expand Down Expand Up @@ -116,4 +117,38 @@ void negotiateUsesProtocolNegotiator() {
Assertions.assertTrue(handler instanceof HttpProtocolNegotiator);
}

@Test
void forceHttp2TlsMissingAlpnFailsStrictHandshake() throws Exception {
final ClientHttpProtocolNegotiationStarter starter = new ClientHttpProtocolNegotiationStarter(
http1Factory(),
http2Factory(),
HttpVersionPolicy.FORCE_HTTP_2,
null,
null,
null);

final ProtocolIOSession ioSession = Mockito.mock(ProtocolIOSession.class);
Mockito.when(ioSession.getTlsDetails()).thenReturn(new TlsDetails(null, null));
final ClientH2PrefaceHandler handler = (ClientH2PrefaceHandler) starter.createHandler(ioSession, null);

Assertions.assertThrows(ProtocolNegotiationException.class, () -> handler.connected(ioSession));
}

@Test
void forceHttp2TlsUnexpectedAlpnFailsHandshake() throws Exception {
final ClientHttpProtocolNegotiationStarter starter = new ClientHttpProtocolNegotiationStarter(
http1Factory(),
http2Factory(),
HttpVersionPolicy.FORCE_HTTP_2,
null,
null,
null);

final ProtocolIOSession ioSession = Mockito.mock(ProtocolIOSession.class);
Mockito.when(ioSession.getTlsDetails()).thenReturn(new TlsDetails(null, ApplicationProtocol.HTTP_1_1.id));
final ClientH2PrefaceHandler handler = (ClientH2PrefaceHandler) starter.createHandler(ioSession, null);

Assertions.assertThrows(ProtocolNegotiationException.class, () -> handler.connected(ioSession));
}

}
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