UNDERTOW-1881 - Add a new exchange attribute for SSL/TLS protocol version

core/src/main/java/io/undertow/attribute/SslProtocolAttribute.java

@@ -0,0 +1,67 @@
+/*
+ * JBoss, Home of Professional Open Source.
+ * Copyright 2024 Red Hat, Inc., and individual contributors
+ * as indicated by the @author tags.
+ *
+ * Licensed 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 io.undertow.attribute;
+
+import io.undertow.server.HttpServerExchange;
+import io.undertow.server.SSLSessionInfo;
+
+public class SslProtocolAttribute implements ExchangeAttribute {
+
+    public static final SslProtocolAttribute INSTANCE = new SslProtocolAttribute();
+
+    @Override
+    public String readAttribute(HttpServerExchange exchange) {
+        SSLSessionInfo ssl = exchange.getConnection().getSslSessionInfo();
+        if(ssl == null) {
+            return null;
+        }
+        return ssl.getSSLSession().getProtocol();
+    }
+
+    @Override
+    public void writeAttribute(HttpServerExchange exchange, String newValue) throws ReadOnlyAttributeException {
+        throw new ReadOnlyAttributeException("SSL Protocol", newValue);
+    }
+
+    @Override
+    public String toString() {
+        return "%{SSL_PROTOCOL}";
+    }
+
+    public static final class Builder implements ExchangeAttributeBuilder {
+
+        @Override
+        public String name() {
+            return "SSL Protocol";
+        }
+
+        @Override
+        public ExchangeAttribute build(final String token) {
+            if (token.equals("%{SSL_PROTOCOL}")) {
+                return INSTANCE;
+            }
+            return null;
+        }
+
+        @Override
+        public int priority() {
+            return 0;
+        }
+    }
+}

core/src/main/resources/META-INF/services/io.undertow.attribute.ExchangeAttributeBuilder

@@ -23,6 +23,7 @@ io.undertow.attribute.PredicateContextAttribute$Builder
 io.undertow.attribute.QueryParameterAttribute$Builder
 io.undertow.attribute.SslClientCertAttribute$Builder
 io.undertow.attribute.SslCipherAttribute$Builder
+io.undertow.attribute.SslProtocolAttribute$Builder
 io.undertow.attribute.SslSessionIdAttribute$Builder
 io.undertow.attribute.ResponseTimeAttribute$Builder
 io.undertow.attribute.PathParameterAttribute$Builder