From c8a46dac5d1b6913d79cfa1cfcbc72763fa4d174 Mon Sep 17 00:00:00 2001
From: zzz <zzz@mail.i2p>
Date: Wed, 29 Aug 2012 13:45:29 +0000
Subject: [PATCH] i2psnark: - Add new flood-resistant KBucket trim policy
- Limit received MsgID size
---
.../src/org/klomp/snark/dht/DHTNodes.java | 4 +-
.../src/org/klomp/snark/dht/KBTrimmer.java | 37 +++++++++++++++++++
.../java/src/org/klomp/snark/dht/MsgID.java | 5 +++
3 files changed, 45 insertions(+), 1 deletion(-)
create mode 100644 apps/i2psnark/java/src/org/klomp/snark/dht/KBTrimmer.java
diff --git a/apps/i2psnark/java/src/org/klomp/snark/dht/DHTNodes.java b/apps/i2psnark/java/src/org/klomp/snark/dht/DHTNodes.java
index 1b2ae428e7..64a650bae8 100644
--- a/apps/i2psnark/java/src/org/klomp/snark/dht/DHTNodes.java
+++ b/apps/i2psnark/java/src/org/klomp/snark/dht/DHTNodes.java
@@ -46,13 +46,15 @@ class DHTNodes {
private static final int MAX_PEERS = 799;
/** Buckets older than this are refreshed - BEP 5 says 15 minutes */
private static final long MAX_BUCKET_AGE = 15*60*1000;
+ private static final int KAD_K = 8;
+ private static final int KAD_B = 1;
public DHTNodes(I2PAppContext ctx, NID me) {
_context = ctx;
_expireTime = MAX_EXPIRE_TIME;
_log = _context.logManager().getLog(DHTNodes.class);
_nodeMap = new ConcurrentHashMap();
- _kad = new KBucketSet(ctx, me, 8, 1);
+ _kad = new KBucketSet(ctx, me, KAD_K, KAD_B, new KBTrimmer(ctx, KAD_K));
}
public void start() {
diff --git a/apps/i2psnark/java/src/org/klomp/snark/dht/KBTrimmer.java b/apps/i2psnark/java/src/org/klomp/snark/dht/KBTrimmer.java
new file mode 100644
index 0000000000..96809cbc21
--- /dev/null
+++ b/apps/i2psnark/java/src/org/klomp/snark/dht/KBTrimmer.java
@@ -0,0 +1,37 @@
+package org.klomp.snark.dht;
+
+import java.util.Set;
+
+import net.i2p.I2PAppContext;
+import net.i2p.kademlia.KBucket;
+import net.i2p.kademlia.KBucketSet;
+
+/**
+ * Removes an element older than 15 minutes, but only if the bucket hasn't changed in 5 minutes.
+ */
+class KBTrimmer implements KBucketSet.KBucketTrimmer<NID> {
+ private final I2PAppContext _ctx;
+ private final int _max;
+
+ private static final long MIN_BUCKET_AGE = 5*60*1000;
+ private static final long MAX_NODE_AGE = 15*60*1000;
+
+ public KBTrimmer(I2PAppContext ctx, int max) {
+ _ctx = ctx;
+ _max = max;
+ }
+
+ public boolean trim(KBucket<NID> kbucket, NID toAdd) {
+ long now = _ctx.clock().now();
+ if (kbucket.getLastChanged() > now - MIN_BUCKET_AGE)
+ return false;
+ Set<NID> entries = kbucket.getEntries();
+ for (NID nid : entries) {
+ if (nid.lastSeen() < now - MAX_NODE_AGE) {
+ if (kbucket.remove(nid))
+ return true;
+ }
+ }
+ return entries.size() < _max;
+ }
+}
diff --git a/apps/i2psnark/java/src/org/klomp/snark/dht/MsgID.java b/apps/i2psnark/java/src/org/klomp/snark/dht/MsgID.java
index 6d53f7c8fb..c28fba5c70 100644
--- a/apps/i2psnark/java/src/org/klomp/snark/dht/MsgID.java
+++ b/apps/i2psnark/java/src/org/klomp/snark/dht/MsgID.java
@@ -14,7 +14,9 @@ import net.i2p.data.ByteArray;
*/
class MsgID extends ByteArray {
+ /** BEP 5: 2 bytes, incremented */
private static final int MY_TOK_LEN = 8;
+ private static final int MAX_TOK_LEN = 16;
/** outgoing - generate a random ID */
public MsgID(I2PAppContext ctx) {
@@ -28,5 +30,8 @@ class MsgID extends ByteArray {
/** incoming - save the ID (arbitrary length) */
public MsgID(byte[] data) {
super(data);
+ // lets not get carried away
+ if (data.length > MAX_TOK_LEN)
+ throw new IllegalArgumentException();
}
}
--
GitLab