[JENKINS-50095] Update X-Remoting-Minimum-Version header in /tcpSlaveAgentListener

core/src/main/java/hudson/TcpSlaveAgentListener.java

@@ -33,6 +33,7 @@ import java.security.interfaces.RSAPublicKey;
 import javax.annotation.Nullable;
 
 import hudson.model.AperiodicWork;
+import hudson.util.VersionNumber;
 import jenkins.model.Jenkins;
 import jenkins.model.identity.InstanceIdentityProvider;
 import jenkins.security.stapler.StaplerAccessibleType;
@@ -153,6 +154,13 @@ public final class TcpSlaveAgentListener extends Thread {
         return StringUtils.join(Jenkins.getInstance().getAgentProtocols(), ", ");
     }
 
+    /**
+     * Gets Remoting minimum supported version to prevent unsupported agents from connecting
+     */
+    public VersionNumber getRemotingMinimumVersion() {
+        return RemotingVersionInfo.getMinimumSupportedVersion();
+    }
+
     @Override
     public void run() {
         try {
@@ -304,7 +312,7 @@ public final class TcpSlaveAgentListener extends Thread {
                     o.write("Jenkins-Session: " + Jenkins.SESSION_HASH + "\r\n");
                     o.write("Client: " + s.getInetAddress().getHostAddress() + "\r\n");
                     o.write("Server: " + s.getLocalAddress().getHostAddress() + "\r\n");
-                    o.write("Remoting-Minimum-Version: " + RemotingVersionInfo.getMinimumSupportedVersion() + "\r\n");
+                    o.write("Remoting-Minimum-Version: " + getRemotingMinimumVersion() + "\r\n");
                     o.flush();
                     s.shutdownOutput();
                 } else {

core/src/main/resources/hudson/TcpSlaveAgentListener/index.jelly

@@ -39,6 +39,8 @@ THE SOFTWARE.
   <st:header name="X-Instance-Identity" value="${app.tcpSlaveAgentListener.identityPublicKey}" />
   <!-- reduce the number of client connection attempts during protocol negotiation -->
   <st:header name="X-Jenkins-Agent-Protocols" value="${app.tcpSlaveAgentListener.agentProtocolNames}"/>
+  <!-- publish minimum supported version of remoting agent -->
+  <st:header name="X-Remoting-Minimum-Version" value="${app.tcpSlaveAgentListener.remotingMinimumVersion}"/>
 
   Jenkins
 </j:jelly>