Path probing

CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 - Support for --log.level
   [#4](https://github.com/netsec-ethz/scion-java-multiping/pull/4)
+- Added path probing for showpaths and --no-probe
+  [#5](https://github.com/netsec-ethz/scion-java-multiping/pull/5)
 
 ### Fixed
 

src/main/java/org/scion/cli/Cli.java

@@ -32,6 +32,7 @@ public static void main(String... args) {
     System.setProperty(org.slf4j.simple.SimpleLogger.DEFAULT_LOG_LEVEL_KEY, "ERROR");
     handleExit(() -> run(args));
     // handleExit(() -> run(new String[] {"traceroute", "66-2:0:18,10.0.0.1"}));
+    // handleExit(() -> run(new String[] {"showpaths", "67-401500"}));
   }
 
   public static void run(String... args) throws IOException {
@@ -207,7 +208,7 @@ static void printUsagePing() {
     println("      --sciond string          SCION Daemon address. (default \"127.0.0.1:30255\")");
     //    println("      --sequence string        Space separated list of hop predicates");
     println("      --shim                   start with SHIM enabled (default disabled).");
-    println("      --timeout duration       timeout per packet (default 1s)");
+    println("      --timeout uint16         timeout per packet in milliseconds (default 1s)");
     println("      --url url                use and resolve a url as destination address");
   }
 
@@ -245,24 +246,21 @@ static void printUsageTraceroute() {
     println("      --sciond string          SCION Daemon address. (default \"127.0.0.1:30255\")");
     //    println("      --sequence string        Space separated list of hop predicates");
     println("      --shim                   start with SHIM enabled (default disabled).");
-    println("      --timeout duration       timeout per packet (default 1s)");
+    println("      --timeout uint16         timeout per packet in milliseconds (default 1s)");
     println("      --url url                use and resolve a url as destination address");
   }
 
   static void printUsageShowpaths() {
     println("'showpaths' lists available paths between the local and the specified");
     println("SCION AS.");
     println("");
-    println("Path probing: Unlike `scion`, jpan-cli does no path probing."); // TODO
-    //    println("By default, the paths are probed. Paths served from the SCION Daemon's might
-    // not");
-    //    println("forward traffic successfully (e.g. if a network link went down, or there is a
-    // black");
-    //    println("hole on the path). To disable path probing, set the appropriate flag.");
+    println("By default, the paths are probed. Paths served from the SCION Daemon's might not");
+    println("forward traffic successfully (e.g. if a network link went down, or there is a black");
+    println("hole on the path). To disable path probing, set the appropriate flag.");
     println("");
-    //    println("If no alive path is discovered, json output is not enabled, and probing is not");
-    //    println("disabled, showpaths will exit with the code 1.");
-    println("If no alive path is discovered, showpaths will exit with the code 1."); // TODO
+    // println("If no alive path is discovered, json output is not enabled, and probing is not");
+    println("If no alive path is discovered, and probing is not");
+    println("disabled, showpaths will exit with the code 1.");
     println("On other errors, showpaths will exit with code 2.");
     //    println("");
     //    printSequenceHelp();
@@ -299,12 +297,12 @@ static void printUsageShowpaths() {
     println(
         "  -m, --maxpaths int           maximum number of paths that are displayed (default 10)");
     //    println("      --no-color               disable colored output");
-    //    println("      --no-probe               Do not probe the paths and print the health
-    // status");
+    println("      --no-probe               Do not probe the paths and print the health status");
+    println("      --port uint16            Use specified local port for probing");
     //    println("  -r, --refresh                Set refresh flag for SCION Daemon path request");
     println("      --sciond string          SCION Daemon address. (default \"127.0.0.1:30255\")");
     //    println("      --sequence string        Space separated list of hop predicates");
-    //    println("      --timeout duration       Timeout (default 5s)");
+    println("      --timeout uint16         Probing timeout in milliseconds (default 5s)");
     //    println("      --tracing.agent string   Tracing agent address");
   }
 

src/main/java/org/scion/cli/Showpaths.java

@@ -22,11 +22,10 @@
 import java.time.Instant;
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
+import java.util.*;
 import org.scion.cli.util.Errors;
 import org.scion.cli.util.ExitCodeException;
+import org.scion.cli.util.Prober;
 import org.scion.jpan.*;
 
 /**
@@ -50,6 +49,9 @@ public class Showpaths {
   private Long isdAs;
   private boolean extended = false;
   private int maxPaths = 10;
+  private Integer port;
+  private final int timeoutMs = 5000;
+  private boolean probePath = true;
 
   public static void main(String... args) {
     handleExit(() -> new Showpaths().run(args));
@@ -102,6 +104,9 @@ private void parseArgs(String[] argsArray) {
         case "--maxpaths":
           maxPaths = parseInt("--maxpaths", args);
           break;
+        case "--no-probe":
+          probePath = false;
+          break;
         case "--sciond":
           daemon = parseAddress("sciond", args);
           break;
@@ -127,6 +132,13 @@ public void run() throws IOException {
       throw new ExitCodeException(1, "No path found from " + src + " to " + dst);
     }
 
+    Map<Integer, Prober.Status> isActive;
+    if (probePath) {
+      isActive = Prober.probe(port, timeoutMs, paths);
+    } else {
+      isActive = new HashMap<>();
+    }
+
     println("Available paths to " + ScionUtil.toStringIA(isdAs));
 
     int id = 0;
@@ -143,23 +155,29 @@ public void run() throws IOException {
       String header = "[" + id++ + "] Hops: " + ScionUtil.toStringPath(meta);
       if (extended) {
         println(header);
-        printExtended(path, localIP);
+        printExtended(path, localIP, isActive.getOrDefault(id, Prober.Status.Unknown));
       } else {
         String compact =
             " MTU: "
                 + meta.getMtu()
                 + " NextHop: "
                 + path.getFirstHopAddress().getHostString()
                 + ":"
-                + path.getFirstHopAddress().getPort()
-                + " LocalIP: "
-                + localIP;
+                + path.getFirstHopAddress().getPort();
+        if (probePath) {
+          compact += " Status: " + isActive.getOrDefault(id, Prober.Status.Unknown);
+        }
+        compact += " LocalIP: " + localIP;
         println(header + compact);
       }
     }
+
+    if (probePath && isActive.isEmpty()) {
+      throw new ExitCodeException(2, "Error: no path alive");
+    }
   }
 
-  private static void printExtended(Path path, String localIP) {
+  private static void printExtended(Path path, String localIP, Prober.Status status) {
     StringBuilder sb = new StringBuilder();
     String NL = System.lineSeparator();
 
@@ -173,8 +191,7 @@ private static void printExtended(Path path, String localIP) {
     sb.append("    LinkType: ").append(toStringLinkType(meta)).append(NL);
     sb.append("    Notes: ").append(toStringNotes(meta)).append(NL);
     sb.append("    SupportsEPIC: ").append(toStringEPIC(meta)).append(NL);
-    // TODO, see private/app/path/pathprobe/paths.go
-    sb.append("    Status: ").append("unknown").append(NL);
+    sb.append("    Status: ").append(status).append(NL);
     // TODO use destination IP from returned packet from probe
     sb.append("    LocalIP: ").append(localIP).append(NL);
 

src/main/java/org/scion/cli/util/Prober.java

@@ -0,0 +1,114 @@
+// Copyright 2026 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.cli.util;
+
+import java.io.IOException;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.scion.jpan.*;
+
+public class Prober {
+
+  public enum Status {
+    // StatusUnknown indicates that it is not clear what state the path is in.
+    Unknown,
+    // StatusTimeout indicates that a reply did come back in time for the path.
+    Timeout,
+    // StatusAlive indicates that the expected reply did come back in time.
+    Alive,
+    // StatusSCMP indicates that an unexpected SCMP packet came in the reply.
+    SCMP;
+  }
+
+  private Prober() {}
+
+  public static Map<Integer, Status> probe(Integer port, int timeoutMs, List<Path> paths) {
+    PingResponseHandler handler = new PingResponseHandler(paths.size());
+
+    // Send all requests
+    ScmpSenderAsync.Builder builder = Scmp.newSenderAsyncBuilder(handler);
+    if (port != null) {
+      builder.setLocalPort(port);
+    }
+    try (ScmpSenderAsync sender = builder.build()) {
+      sender.setTimeOut(timeoutMs);
+      for (Path path : paths) {
+        sender.sendTracerouteLast(path);
+      }
+
+      // Wait for all messages to be received, BEFORE closing the "sender".
+      handler.await();
+    } catch (IOException e) {
+      throw new ExitCodeException(2, e.getMessage());
+    }
+
+    return handler.result;
+  }
+
+  private static class PingResponseHandler implements ScmpSenderAsync.ResponseHandler {
+    private final Map<Integer, Status> result = new ConcurrentHashMap<>();
+    private final CountDownLatch barrier;
+    private final AtomicInteger errors = new AtomicInteger();
+    private final int nPaths;
+
+    private PingResponseHandler(int nPaths) {
+      this.nPaths = nPaths;
+      barrier = new CountDownLatch(nPaths);
+    }
+
+    @Override
+    public void onResponse(Scmp.TimedMessage msg) {
+      barrier.countDown();
+      result.put(msg.getSequenceNumber(), Status.Alive);
+    }
+
+    @Override
+    public void onTimeout(Scmp.TimedMessage msg) {
+      barrier.countDown();
+      result.put(msg.getSequenceNumber(), Status.Timeout);
+    }
+
+    @Override
+    public void onError(Scmp.ErrorMessage msg) {
+      errors.incrementAndGet();
+      barrier.countDown();
+      result.put(msg.getSequenceNumber(), Status.SCMP);
+    }
+
+    @Override
+    public void onException(Throwable t) {
+      errors.incrementAndGet();
+      barrier.countDown();
+    }
+
+    void await() {
+      try {
+        if (!barrier.await(1100, TimeUnit.MILLISECONDS)) {
+          throw new IllegalStateException("Missing messages: " + barrier.getCount() + "/" + nPaths);
+        }
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+        throw new IllegalStateException(e);
+      }
+    }
+
+    public boolean hasErrors() {
+      return errors.get() > 0;
+    }
+  }
+}

src/main/java/org/scion/cli/util/Util.java

@@ -115,6 +115,7 @@ public static void handleExit(Runner runner) {
       }
       System.exit(e.exitCode());
     } catch (Exception e) {
+      e.printStackTrace();
       System.exit(2);
     }
   }