Responder

Author: tzaeschke

.gitignore

@@ -25,9 +25,5 @@ replay_pid*
 
 .idea
 target/
-cert.crt
-cert.csr
-cert.key
-http3-response.*
 
 dependency-reduced-pom.xml

EchoResponderConfig.json

@@ -0,0 +1,4 @@
+{
+  "localPort": 30041,
+  "consoleOutput": true
+}

README.md

@@ -7,6 +7,7 @@ MultiPing provides several tools:
 * `DownloadAssignmentList` for downloading a list of known ISD/AS assignment
 * `EchoAll` for sending a single traceroute to all known ASes along the shortest path (default behaviour)
 * `EchoRepeat` for repeatedly probing (traceroute) multiple paths to multiple ASes.
+* `EchoResponder` for responding to incoming echo requests.
 
 # `DownloadAssignmentList`
 
@@ -102,6 +103,17 @@ This shows a LOCAL_AS and a NO_PATH event:
 71-2:0:4a,,2024-09-13T15:46:16.554705200Z,NO_PATH,0,[]
 ```
 
+# `EchoResponder`
+
+The `EchoResponder` can be configured with a configuration file `EchoResponderConfig.json`, it has two options:
+
+```json
+{
+  "localPort": 30041,
+  "consoleOutput": true
+}
+```
+
 # Troubleshooting
 
 ## No DNS search domain found. Please check your /etc/resolv.conf or similar.
@@ -110,5 +122,5 @@ This happens, for example, on Windows when using a VPN. One solution is to execu
 the example works only for `ethz.ch`):
 
 ```
-java -DSCION_DNS_SEARCH_DOMAINS=ethz.ch.  -jar target/scion-multiping-0.0.1-ALPHA-SNAPSHOT-shaded.jar
+java -Dorg.scion.dnsSearchDomains=ethz.ch. -jar target/scion-multiping-0.0.1-ALPHA-SNAPSHOT-shaded.jar
 ```

src/main/java/org/scion/multiping/EchoRepeat.java

@@ -63,7 +63,7 @@ public EchoRepeat(int localPort) {
   }
 
   public static void main(String[] args) throws IOException {
-    //    System.setProperty(Constants.PROPERTY_DNS_SEARCH_DOMAINS, "ethz.ch.");
+    // System.setProperty(Constants.PROPERTY_DNS_SEARCH_DOMAINS, "ethz.ch.");
 
     config = Config.read(FILE_CONFIG);
     PRINT = config.consoleOutput;

src/main/java/org/scion/multiping/EchoRepeatBlocking.java

@@ -47,8 +47,6 @@
  */
 public class EchoRepeatBlocking {
   private static final String FILE_CONFIG = "EchoRepeatConfig.json";
-  private static final String FILE_INPUT = "EchoRepeatDestinations-short.csv";
-  private static final String FILE_OUTPUT = "EchoRepeatOutput.csv";
 
   private final int localPort;
 
@@ -63,9 +61,10 @@ public class EchoRepeatBlocking {
   private int nPathTimeout = 0;
 
   private static Config config;
+  private static FileWriter fileWriter;
+
   private static final List<Result> results = new ArrayList<>();
   private static final List<org.scion.multiping.util.Record> records = new ArrayList<>();
-  private static FileWriter fileWriter;
 
   private enum Policy {
     /** Fastest path using SCMP traceroute */
@@ -86,17 +85,17 @@ public EchoRepeatBlocking(int localPort) {
   }
 
   public static void main(String[] args) throws IOException {
-    PRINT = true;
     // System.setProperty(Constants.PROPERTY_DNS_SEARCH_DOMAINS, "ethz.ch.");
 
     config = Config.read(FILE_CONFIG);
+    PRINT = config.consoleOutput;
+
     // Output: ISD/AS, remote IP, time, hopCount, path, [pings]
-    fileWriter = new FileWriter(FILE_OUTPUT);
+    fileWriter = new FileWriter(config.outputFile);
 
     // Local port must be 30041 for networks that expect a dispatcher
-    EchoRepeatBlocking demo = new EchoRepeatBlocking(30041);
-    List<ParseAssignments.HostEntry> list = ParseAssignments.getList(FILE_INPUT);
-    // List<ParseAssignments.HostEntry> list = DownloadAssignments.getList();
+    EchoRepeatBlocking demo = new EchoRepeatBlocking(config.localPort);
+    List<ParseAssignments.HostEntry> list = ParseAssignments.getList(config.isdAsFile);
     for (int i = 0; i < config.roundRepeatCnt; i++) {
       Instant start = Instant.now();
       for (ParseAssignments.HostEntry e : list) {

src/main/java/org/scion/multiping/EchoResponder.java

@@ -0,0 +1,53 @@
+// Copyright 2024 ETH Zurich
+//
+// 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 org.scion.multiping;
+
+import org.scion.jpan.*;
+import org.scion.multiping.util.Config;
+import org.scion.multiping.util.Util;
+
+import java.io.IOException;
+
+import static org.scion.multiping.util.Util.PRINT;
+import static org.scion.multiping.util.Util.println;
+
+/**
+ * A simple echo responder that responds to SCMP echo requests.
+ */
+public class EchoResponder {
+    private static final String FILE_CONFIG = "EchoResponderConfig.json";
+
+    public static void main(String[] args) throws IOException {
+        Config config = Config.read(FILE_CONFIG);
+        PRINT = config.consoleOutput;
+
+        try (ScmpChannel responder = Scmp.createChannel(Constants.SCMP_PORT)) {
+            responder.setScmpErrorListener(EchoResponder::printError);
+            responder.setOption(ScionSocketOptions.SCION_API_THROW_PARSER_FAILURE, true);
+            responder.setScmpEchoListener(EchoResponder::print);
+            responder.setUpScmpEchoResponder();
+        }
+    }
+
+    private static boolean print(Scmp.EchoMessage msg) {
+        Util.print("Received: " + msg.getTypeCode().getText() + " from " + msg.getPath().getRemoteAddress() + "via ");
+        Util.println(ScionUtil.toStringPath(msg.getPath().getMetadata()));
+        return true;
+    }
+
+    private static void printError(Scmp.Message msg) {
+        println("ERROR: " + msg.getTypeCode().getText());
+    }
+}