From ddc3ef8db36574ca7006a7fbed3bfa00bdabe5b6 Mon Sep 17 00:00:00 2001
From: dev <dev@robertfoss.se>
Date: Sat, 4 Apr 2015 00:05:29 +0000
Subject: [PATCH 1/2] Removed unnecessry buffering

---
 .../src/net/i2p/data/i2np/I2NPMessageImpl.java  | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/router/java/src/net/i2p/data/i2np/I2NPMessageImpl.java b/router/java/src/net/i2p/data/i2np/I2NPMessageImpl.java
index be6b54aa8..432a5e813 100644
--- a/router/java/src/net/i2p/data/i2np/I2NPMessageImpl.java
+++ b/router/java/src/net/i2p/data/i2np/I2NPMessageImpl.java
@@ -199,24 +199,23 @@ public abstract class I2NPMessageImpl extends DataStructureImpl implements I2NPM
         cur += DataHelper.DATE_LENGTH;
         int size = (int)DataHelper.fromLong(data, cur, 2);
         cur += 2;
-        //Hash h = new Hash();
-        byte hdata[] = new byte[CHECKSUM_LENGTH];
-        System.arraycopy(data, cur, hdata, 0, CHECKSUM_LENGTH);
-        cur += CHECKSUM_LENGTH;
-        //h.setData(hdata);
 
         if (cur + size > data.length || headerSize + size > maxLen)
-            throw new I2NPMessageException("Payload is too short [" 
+            throw new I2NPMessageException("Payload is too short ["
                                            + "data.len=" + data.length
                                            + "maxLen=" + maxLen
                                            + " offset=" + offset
-                                           + " cur=" + cur 
+                                           + " cur=" + cur
                                            + " wanted=" + size + "]: " + getClass().getSimpleName());
 
         int sz = Math.min(size, maxLen - headerSize);
         byte[] calc = SimpleByteCache.acquire(Hash.HASH_LENGTH);
-        _context.sha().calculateHash(data, cur, sz, calc, 0);
-        boolean eq = DataHelper.eq(hdata, 0, calc, 0, CHECKSUM_LENGTH);
+        
+        // Compare the checksum in data to the checksum of the data after the checksum
+        _context.sha().calculateHash(data, cur + CHECKSUM_LENGTH, sz, calc, 0);
+        boolean eq = DataHelper.eq(data, cur, calc, 0, CHECKSUM_LENGTH);
+        cur += CHECKSUM_LENGTH;
+
         SimpleByteCache.release(calc);
         if (!eq)
             throw new I2NPMessageException("Bad checksum on " + size + " byte I2NP " + getClass().getSimpleName());

From 0c90162e20ea8e5e07715d652282dfac49240cd3 Mon Sep 17 00:00:00 2001
From: dev <dev@robertfoss.se>
Date: Sat, 4 Apr 2015 02:27:24 +0000
Subject: [PATCH 2/2] Copy directly into buffer without intermediate buffer

---
 core/java/src/net/i2p/crypto/SHA256Generator.java | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/core/java/src/net/i2p/crypto/SHA256Generator.java b/core/java/src/net/i2p/crypto/SHA256Generator.java
index 162b9d0c1..217147f7b 100644
--- a/core/java/src/net/i2p/crypto/SHA256Generator.java
+++ b/core/java/src/net/i2p/crypto/SHA256Generator.java
@@ -2,6 +2,7 @@ package net.i2p.crypto;
 
 import gnu.crypto.hash.Sha256Standalone;
 
+import java.security.DigestException;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.concurrent.LinkedBlockingQueue;
@@ -20,6 +21,7 @@ public final class SHA256Generator {
     private final LinkedBlockingQueue<MessageDigest> _digests;
 
     private static final boolean _useGnu;
+
     static {
         boolean useGnu = false;
         try {
@@ -53,13 +55,13 @@ public final class SHA256Generator {
 
     /**
      * Calculate the hash and cache the result.
+     * @param source what to hash
      */
     public final Hash calculateHash(byte[] source, int start, int len) {
         MessageDigest digest = acquire();
         digest.update(source, start, len);
         byte rv[] = digest.digest();
         release(digest);
-        //return new Hash(rv);
         return Hash.create(rv);
     }
     
@@ -71,9 +73,12 @@ public final class SHA256Generator {
     public final void calculateHash(byte[] source, int start, int len, byte out[], int outOffset) {
         MessageDigest digest = acquire();
         digest.update(source, start, len);
-        byte rv[] = digest.digest();
+        try {
+            digest.digest(out, outOffset, Hash.HASH_LENGTH);
+        } catch (DigestException e) {
+            throw new RuntimeException(e);
+        }
         release(digest);
-        System.arraycopy(rv, 0, out, outOffset, rv.length);
     }
     
     private MessageDigest acquire() {