Implement ext-info-in-auth@openssh.com extension

# Conflicts:
#	sshd-common/src/main/java/org/apache/sshd/common/kex/extension/KexExtensions.java
#	sshd-core/src/main/java/org/apache/sshd/common/kex/extension/DefaultClientKexExtensionHandler.java

Author: gnodet

sshd-common/src/main/java/org/apache/sshd/common/kex/extension/KexExtensions.java

@@ -39,6 +39,7 @@
 import org.apache.sshd.common.NamedResource;
 import org.apache.sshd.common.kex.extension.parser.DelayCompression;
 import org.apache.sshd.common.kex.extension.parser.Elevation;
+import org.apache.sshd.common.kex.extension.parser.ExtInfoInAuth;
 import org.apache.sshd.common.kex.extension.parser.NoFlowControl;
 import org.apache.sshd.common.kex.extension.parser.ServerSignatureAlgorithms;
 import org.apache.sshd.common.util.GenericUtils;
@@ -84,7 +85,8 @@ public final class KexExtensions {
             ServerSignatureAlgorithms.INSTANCE,
             NoFlowControl.INSTANCE,
             Elevation.INSTANCE,
-            DelayCompression.INSTANCE)
+            DelayCompression.INSTANCE,
+            ExtInfoInAuth.INSTANCE)
             .collect(Collectors.toMap(
                     NamedResource::getName, Function.identity(),
                     MapEntryUtils.throwingMerger(), () -> new TreeMap<>(String.CASE_INSENSITIVE_ORDER)));

sshd-common/src/main/java/org/apache/sshd/common/kex/extension/parser/ExtInfoInAuth.java

@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.sshd.common.kex.extension.parser;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+import org.apache.sshd.common.util.buffer.Buffer;
+
+/**
+ * @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
+ * @see    <A HREF=
+ *         "https://github.com/openssh/openssh-portable/blob/V_9_8/PROTOCOL#L167-L184">ext-info-in-auth@openssh.com</A>
+ */
+public class ExtInfoInAuth extends AbstractKexExtensionParser<String> {
+
+    public static final String NAME = "ext-info-in-auth@openssh.com";
+
+    public static final ExtInfoInAuth INSTANCE = new ExtInfoInAuth();
+
+    public ExtInfoInAuth() {
+        super(NAME);
+    }
+
+    @Override
+    protected void encode(String value, Buffer buffer) throws IOException {
+        buffer.putString(value);
+    }
+
+    @Override
+    public String parseExtension(byte[] data, int off, int len) throws IOException {
+        return (len <= 0) ? "" : new String(data, off, len, StandardCharsets.UTF_8);
+    }
+
+    @Override
+    public String parseExtension(Buffer buffer) throws IOException {
+        return parseExtension(buffer.array(), buffer.rpos(), buffer.available());
+    }
+}

sshd-core/src/main/java/org/apache/sshd/common/kex/extension/DefaultClientKexExtensionHandler.java

@@ -32,6 +32,7 @@
 
 import org.apache.sshd.common.AttributeRepository.AttributeKey;
 import org.apache.sshd.common.NamedFactory;
+import org.apache.sshd.common.kex.extension.parser.ExtInfoInAuth;
 import org.apache.sshd.common.kex.extension.parser.HostBoundPubkeyAuthentication;
 import org.apache.sshd.common.kex.extension.parser.ServerSignatureAlgorithms;
 import org.apache.sshd.common.session.Session;
@@ -165,5 +166,7 @@ public void sendKexExtensions(Session session, KexPhase phase) throws Exception
      * @param marshaller {@link BiConsumer} writing the extensions into an SSH message
      */
     public void collectExtensions(Session session, KexPhase phase, BiConsumer<String, Object> marshaller) {
+        // ext-info-in-auth@openssh.com
+        marshaller.accept(ExtInfoInAuth.NAME, "");
     }
 }