Merge pull request #2496 from jenkinsci/JENKINS-37223

[FIXED JENKINS-37223]

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

@@ -23,6 +23,9 @@
  */
 package hudson;
 
+import java.io.ByteArrayInputStream;
+import java.io.SequenceInputStream;
+import java.io.Writer;
 import java.nio.charset.Charset;
 import java.security.interfaces.RSAPublicKey;
 import javax.annotation.Nullable;
@@ -50,7 +53,9 @@ import java.nio.channels.ServerSocketChannel;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.apache.commons.codec.binary.Base64;
+import org.apache.commons.io.Charsets;
 import org.apache.commons.io.IOUtils;
+import org.apache.commons.io.output.NullOutputStream;
 import org.apache.commons.lang.StringUtils;
 
 /**
@@ -202,7 +207,19 @@ public final class TcpSlaveAgentListener extends Thread {
                         new BufferedWriter(new OutputStreamWriter(s.getOutputStream(),"UTF-8")),
                         true); // DEPRECATED: newer protocol shouldn't use PrintWriter but should use DataOutputStream
 
-                String s = in.readUTF();
+                // peek the first few bytes to determine what to do with this client
+                byte[] head = new byte[10];
+                in.readFully(head);
+
+                String header = new String(head, Charsets.US_ASCII);
+                if (header.startsWith("GET ")) {
+                    // this looks like an HTTP client
+                    respondHello(header,s);
+                    return;
+                }
+
+                // otherwise assume this is AgentProtocol and start from the beginning
+                String s = new DataInputStream(new SequenceInputStream(new ByteArrayInputStream(head),in)).readUTF();
 
                 if(s.startsWith("Protocol:")) {
                     String protocol = s.substring(9);
@@ -235,6 +252,49 @@ public final class TcpSlaveAgentListener extends Thread {
             }
         }
 
+        /**
+         * Respond to HTTP request with simple diagnostics.
+         * Primarily used to test the low-level connectivity.
+         */
+        private void respondHello(String header, Socket s) throws IOException {
+            try {
+                Writer o = new OutputStreamWriter(s.getOutputStream(), "UTF-8");
+
+                if (header.startsWith("GET / ")) {
+                    o.write("HTTP/1.0 200 OK\r\n");
+                    o.write("Content-Type: text/plain;charset=UTF-8\r\n");
+                    o.write("\r\n");
+                    o.write("Jenkins-Agent-Protocols: ");
+                    boolean first = true;
+                    for (AgentProtocol p : AgentProtocol.all()) {
+                        if (first)  first = false;
+                        else        o.write(",");
+                        o.write(p.getName());
+                    }
+                    o.write("\r\n");
+                    o.write("Jenkins-Version: " + Jenkins.VERSION + "\r\n");
+                    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.flush();
+                    s.shutdownOutput();
+                } else {
+                    o.write("HTTP/1.0 404 Not Found\r\n");
+                    o.write("Content-Type: text/plain;charset=UTF-8\r\n");
+                    o.write("\r\n");
+                    o.write("Not Found\r\n");
+                    o.flush();
+                    s.shutdownOutput();
+                }
+
+                InputStream i = s.getInputStream();
+                IOUtils.copy(i, new NullOutputStream());
+                s.shutdownInput();
+            } finally {
+                s.close();
+            }
+        }
+
         private void error(PrintWriter out, String msg) throws IOException {
             out.println(msg);
             LOGGER.log(Level.WARNING,"Connection #"+id+" is aborted: "+msg);

test/src/test/java/hudson/TcpSlaveAgentListenerTest.java

@@ -2,8 +2,11 @@ package hudson;
 
 import com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException;
 import com.gargoylesoftware.htmlunit.Page;
+import com.gargoylesoftware.htmlunit.TextPage;
 import com.gargoylesoftware.htmlunit.html.HtmlPage;
 import hudson.remoting.Base64;
+
+import java.io.IOException;
 import java.security.KeyFactory;
 import java.security.KeyPair;
 import java.security.KeyPairGenerator;
@@ -14,14 +17,17 @@ import java.security.interfaces.RSAPublicKey;
 import java.security.spec.InvalidKeySpecException;
 import java.security.spec.PKCS8EncodedKeySpec;
 import javax.annotation.Nullable;
+
+import jenkins.model.Jenkins;
 import jenkins.model.identity.InstanceIdentityProvider;
+import jenkins.security.security218.ysoserial.ExecBlockingSecurityManager.ExecException;
 import org.junit.Rule;
 import org.junit.Test;
 import org.jvnet.hudson.test.JenkinsRule;
+import org.jvnet.hudson.test.JenkinsRule.WebClient;
 import org.jvnet.hudson.test.TestExtension;
 
-import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.notNullValue;
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.fail;
 
@@ -43,4 +49,21 @@ public class TcpSlaveAgentListenerTest {
         Page p = r.createWebClient().goTo("tcpSlaveAgentListener", "text/plain");
         assertThat(p.getWebResponse().getResponseHeaderValue("X-Instance-Identity"), notNullValue());
     }
+
+    @Test
+    public void diagnostics() throws Exception {
+        r.getInstance().setSlaveAgentPort(0);
+        int p = r.jenkins.getTcpSlaveAgentListener().getPort();
+        WebClient wc = r.createWebClient();
+        TextPage text = (TextPage) wc.getPage("http://localhost:"+p+"/");
+        String c = text.getContent();
+        assertThat(c,containsString(Jenkins.VERSION));
+
+        try {
+            wc.getPage("http://localhost:"+p+"/xxx");
+            fail("Expected 404");
+        } catch (FailingHttpStatusCodeException e) {
+            assertThat(e.getStatusCode(),equalTo(404));
+        }
+    }
 }