Local caching of address/ISD/AS info

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Demo cleanup an new `ScmpShowpathsDemo`.
   [#49](https://github.com/netsec-ethz/scion-java-client/pull/49)
 - Channel demo cleanup. [#52](https://github.com/netsec-ethz/scion-java-client/pull/52)
+- Address/ISD/AS caching. [#54](https://github.com/netsec-ethz/scion-java-client/pull/54)
 
 ### Changed
 - BREAKING CHANGE: Changed maven artifactId to "client"

src/main/java/org/scion/jpan/ScionService.java

@@ -36,6 +36,7 @@
 import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicLong;
+import org.scion.internal.SimpleCache;
 import org.scion.jpan.internal.DNSHelper;
 import org.scion.jpan.internal.HostsFileParser;
 import org.scion.jpan.internal.ScionBootstrapper;
@@ -81,6 +82,7 @@ public class ScionService {
   private Thread shutdownHook;
   private final java.nio.channels.DatagramChannel[] ifDiscoveryChannel = {null};
   private final HostsFileParser hostsFile = new HostsFileParser();
+  private final SimpleCache<String, ScionAddress> scionAddressCache = new SimpleCache<>(100);
 
   protected enum Mode {
     DAEMON,
@@ -294,24 +296,26 @@ List<Daemon.Path> getPathListDaemon(long srcIsdAs, long dstIsdAs) {
   /**
    * Requests paths from the local ISD/AS to the destination.
    *
-   * @param dstAddress Destination IP address
+   * @param dstAddress Destination IP address. It will try to perform a DNS look up to map the
+   *     hostName to SCION address.
    * @return All paths returned by the path service.
    * @throws IOException if an errors occurs while querying paths.
    */
   public List<RequestPath> getPaths(InetSocketAddress dstAddress) throws IOException {
-    long dstIsdAs = getIsdAs(dstAddress.getHostString());
-    return getPaths(dstIsdAs, dstAddress);
+    ScionAddress sa = getScionAddress(dstAddress.getHostName());
+    return getPaths(sa.getIsdAs(), sa.getInetAddress(), dstAddress.getPort());
   }
 
   /**
    * Request paths from the local ISD/AS to the destination.
    *
    * @param dstIsdAs Destination ISD/AS
-   * @param dstAddress Destination IP address
+   * @param dstScionAddress Destination IP address. Must belong to a SCION enabled end host.
    * @return All paths returned by the path service.
    */
-  public List<RequestPath> getPaths(long dstIsdAs, InetSocketAddress dstAddress) {
-    return getPaths(dstIsdAs, dstAddress.getAddress(), dstAddress.getPort());
+  public List<RequestPath> getPaths(long dstIsdAs, InetSocketAddress dstScionAddress) {
+    // TODO change method API name to make clear that this requires a SCION IP.
+    return getPaths(dstIsdAs, dstScionAddress.getAddress(), dstScionAddress.getPort());
   }
 
   /**
@@ -372,6 +376,11 @@ public long getLocalIsdAs() {
    * @throws ScionException if the DNS/TXT lookup did not return a (valid) SCION address.
    */
   public long getIsdAs(String hostName) throws ScionException {
+    ScionAddress scionAddress = scionAddressCache.get(hostName);
+    if (scionAddress != null) {
+      return scionAddress.getIsdAs();
+    }
+
     // Look for TXT in application properties
     String txtFromProperties = findTxtRecordInProperties(hostName);
     if (txtFromProperties != null) {
@@ -408,6 +417,11 @@ public long getIsdAs(String hostName) throws ScionException {
    * @throws ScionException if the DNS/TXT lookup did not return a (valid) SCION address.
    */
   public ScionAddress getScionAddress(String hostName) throws ScionException {
+    ScionAddress scionAddress = scionAddressCache.get(hostName);
+    if (scionAddress != null) {
+      return scionAddress;
+    }
+
     // Look for TXT in application properties
     String txtFromProperties = findTxtRecordInProperties(hostName);
     if (txtFromProperties != null) {
@@ -433,12 +447,18 @@ public ScionAddress getScionAddress(String hostName) throws ScionException {
     ScionAddress fromDNS =
         DNSHelper.queryTXT(hostName, DNS_TXT_KEY, x -> parseTxtRecord(x, hostName));
     if (fromDNS != null) {
-      return fromDNS;
+      return addToCache(fromDNS);
     }
 
     throw new ScionException("No DNS TXT entry \"scion\" found for host: " + hostName);
   }
 
+  private ScionAddress addToCache(ScionAddress address) {
+    scionAddressCache.put(address.getHostName(), address);
+    scionAddressCache.put(address.getInetAddress().getHostAddress(), address);
+    return address;
+  }
+
   private boolean isLocalhost(String hostName) {
     return hostName.startsWith("127.0.0.")
         || "::1".equals(hostName)

src/main/java/org/scion/jpan/internal/SimpleCache.java

@@ -0,0 +1,103 @@
+// 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.internal;
+
+import java.util.HashMap;
+import java.util.TreeMap;
+
+/**
+ * A simple cache that min/max watermark. Once max watermark is reached, the cache removes entries
+ * until min watermark is reached. Least recently accessed entries are removed first.
+ *
+ * @param <K> The key
+ * @param <V> The value
+ */
+public class SimpleCache<K, V> {
+  private final TreeMap<Long, Entry> ageMap = new TreeMap<>();
+  private final HashMap<K, Entry> lookupMap = new HashMap<>();
+
+  private int capacity;
+  private long opCount = 0;
+
+  public SimpleCache(int capacity) {
+    if (capacity < 1) {
+      throw new IllegalArgumentException();
+    }
+    this.capacity = capacity;
+  }
+
+  public void put(K key, V value) {
+    Entry e = lookupMap.get(key);
+    if (e == null) {
+      e = new Entry(opCount++, key, value);
+      checkCapacity(1);
+      lookupMap.put(key, e);
+    } else {
+      ageMap.remove(e.age);
+      e.age = opCount++;
+      e.value = value;
+    }
+    ageMap.put(e.age, e);
+  }
+
+  public V get(K key) {
+    Entry e = lookupMap.get(key);
+    if (e == null) {
+      return null;
+    }
+
+    ageMap.remove(e.age);
+    e.age = opCount++;
+    ageMap.put(e.age, e);
+
+    return e.value;
+  }
+
+  public void clear() {
+    lookupMap.clear();
+    ageMap.clear();
+  }
+
+  public void setCapacity(int capacity) {
+    if (capacity < 1) {
+      throw new IllegalArgumentException();
+    }
+    this.capacity = capacity;
+    checkCapacity(0);
+  }
+
+  public int getCapacity() {
+    return capacity;
+  }
+
+  private void checkCapacity(int spare) {
+    while (lookupMap.size() + spare > capacity) {
+      Entry e = ageMap.pollFirstEntry().getValue();
+      lookupMap.remove(e.key);
+    }
+  }
+
+  private class Entry {
+    private long age;
+    private final K key;
+    private V value;
+
+    public Entry(long l, K key, V value) {
+      this.age = l;
+      this.key = key;
+      this.value = value;
+    }
+  }
+}

src/test/java/org/scion/jpan/internal/SimpleCacheTest.java

@@ -0,0 +1,117 @@
+// 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.internal;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class SimpleCacheTest {
+
+  private static class Pair {
+    int i;
+    String s;
+
+    Pair(int i, String s) {
+      this.i = i;
+      this.s = s;
+    }
+  }
+
+  @Test
+  void testInsertOnly() {
+    SimpleCache<Integer, Pair> cache = new SimpleCache<>(10);
+    List<Pair> list = new ArrayList<>();
+
+    for (int i = 0; i < 30; i++) {
+      Pair p = new Pair(i, Integer.toString(i));
+      cache.put(i, p);
+      list.add(p);
+    }
+
+    // Test latest 10 remain
+    for (int i = 0; i < list.size(); i++) {
+      if (i < 20) {
+        assertNull(cache.get(i));
+      } else {
+        assertEquals(list.get(i), cache.get(i));
+      }
+    }
+  }
+
+  @Test
+  void testMultiGet() {
+    SimpleCache<Integer, Pair> cache = new SimpleCache<>(10);
+    List<Pair> list = new ArrayList<>();
+
+    for (int i = 0; i < 30; i++) {
+      Pair p = new Pair(i, Integer.toString(i));
+      cache.put(i, p);
+      list.add(p);
+      // keep using the first 5 entries
+      assertNotNull(cache.get(i % 5));
+    }
+
+    // Test latest 5 remain and most used 5 remain
+    for (int i = 0; i < list.size(); i++) {
+      if (i >= 5 && i < 25) {
+        assertNull(cache.get(i));
+      } else {
+        assertEquals(list.get(i), cache.get(i));
+      }
+    }
+  }
+
+  @Test
+  void testReduceCapacity() {
+    SimpleCache<Integer, Pair> cache = new SimpleCache<>(10);
+    List<Pair> list = new ArrayList<>();
+
+    for (int i = 0; i < 30; i++) {
+      Pair p = new Pair(i, Integer.toString(i));
+      cache.put(i, p);
+      list.add(p);
+      // keep using the first 2 entries
+      assertNotNull(cache.get(i % 2));
+    }
+
+    cache.setCapacity(5);
+    assertEquals(5, cache.getCapacity());
+
+    // Test latest 3 remain and most used 2 remain
+    for (int i = 0; i < list.size(); i++) {
+      if (i >= 2 && i < 27) {
+        assertNull(cache.get(i));
+      } else {
+        assertEquals(list.get(i), cache.get(i));
+      }
+    }
+  }
+
+  @Test
+  void testSetCapacity() {
+    SimpleCache<Integer, Pair> cache = new SimpleCache<>(42);
+    assertEquals(42, cache.getCapacity());
+
+    cache.setCapacity(100);
+    assertEquals(100, cache.getCapacity());
+
+    assertThrows(IllegalArgumentException.class, () -> cache.setCapacity(0));
+
+    assertThrows(IllegalArgumentException.class, () -> new SimpleCache<>(0));
+  }
+}

src/test/java/org/scion/jpan/testutil/DNSUtil.java

@@ -21,6 +21,28 @@
 
 public class DNSUtil {
 
+  public static InetAddress install(String asHost, byte[] addrBytes) {
+    try {
+      Name name = Name.fromString(asHost + ".");
+      Cache c = Lookup.getDefaultCache(DClass.IN);
+      if (addrBytes.length == 4) {
+        ARecord a = new ARecord(name, DClass.IN, 5000, InetAddress.getByAddress(addrBytes));
+        c.addRecord(a, 10);
+        // remove trailing top-level `.`
+        return InetAddress.getByAddress(asHost, a.getAddress().getAddress());
+      } else if (addrBytes.length == 16) {
+        AAAARecord a = new AAAARecord(name, DClass.IN, 5000, InetAddress.getByAddress(addrBytes));
+        c.addRecord(a, 10);
+        // remove trailing top-level `.`
+        return InetAddress.getByAddress(asHost, a.getAddress().getAddress());
+      } else {
+        throw new IllegalArgumentException();
+      }
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
   public static void installNAPTR(String asHost, byte[] topoAddr, int topoPort) {
     installNAPTR(asHost, topoAddr, "x-sciondiscovery=" + topoPort, "x-sciondiscovery:tcp");
   }
@@ -60,7 +82,7 @@ public static void installScionTXT(String asHost, String isdAs, String ipAddress
 
   public static void installTXT(String asHost, String entry) {
     try {
-      Name name = Name.fromString(asHost + "."); // "inf.ethz.ch.";
+      Name name = Name.fromString(asHost + ".");
       Cache c = Lookup.getDefaultCache(DClass.IN);
       TXTRecord txt = new TXTRecord(name, DClass.IN, 5000, entry);
       c.addRecord(txt, 10);
@@ -72,4 +94,15 @@ public static void installTXT(String asHost, String entry) {
   public static void clear() {
     Lookup.setDefaultCache(new Cache(), DClass.IN);
   }
+
+  private static Name toName(String hostName) {
+    try {
+      if (hostName.endsWith(".")) {
+        return Name.fromString(hostName);
+      }
+      return Name.fromString(hostName + ".");
+    } catch (TextParseException e) {
+      throw new RuntimeException(e);
+    }
+  }
 }