Use HMAC for authenticating remote LOB id's, removing the need for maintaining a…

Use HMAC for authenticating remote LOB id's, removing the need for maintaining a cache, and removing the limit on the number of LOBs per result set.

h2/src/main/org/h2/engine/SessionRemote.java

@@ -698,7 +698,9 @@ public class SessionRemote extends SessionWithState implements DataHandler {
                 traceOperation("LOB_READ", (int) lobId);
                 transfer.writeInt(SessionRemote.LOB_READ);
                 transfer.writeLong(lobId);
+                if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_12) {
                     transfer.writeBytes(hmac);
+                }
                 transfer.writeLong(offset);
                 transfer.writeInt(length);
                 done(transfer);

h2/src/main/org/h2/server/TcpServerThread.java

@@ -37,6 +37,7 @@ import org.h2.util.SmallMap;
 import org.h2.util.StringUtils;
 import org.h2.value.Transfer;
 import org.h2.value.Value;
+import org.h2.value.ValueLobDb;
 
 /**
  * One server thread is opened per client connection.
@@ -50,7 +51,10 @@ public class TcpServerThread implements Runnable {
     private Thread thread;
     private Command commit;
     private SmallMap cache = new SmallMap(SysProperties.SERVER_CACHED_OBJECTS);
-    private SmallLRUCache<Long, CachedInputStream> lobs = SmallLRUCache.newInstance(SysProperties.SERVER_CACHED_OBJECTS);
+    private SmallLRUCache<Long, CachedInputStream> lobs =
+        SmallLRUCache.newInstance(Math.max(
+                SysProperties.SERVER_CACHED_OBJECTS,
+                SysProperties.SERVER_RESULT_SET_FETCH_SIZE * 5));
     private int threadId;
     private int clientVersion;
     private String sessionId;
@@ -392,14 +396,28 @@ public class TcpServerThread implements Runnable {
             break;
         }
         case SessionRemote.LOB_READ: {
-            byte[] hmac = transfer.readBytes();
             long lobId = transfer.readLong();
+            byte[] hmac;
+            CachedInputStream in;
+            if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_11) {
+                if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_12) {
+                    hmac = transfer.readBytes();
                     transfer.verifyLobMac(hmac, lobId);
-            CachedInputStream in = lobs.get(lobId);
+                } else {
+                    hmac = null;
+                }
+                in = lobs.get(lobId);
                 if (in == null) {
                     in = new CachedInputStream(null);
                     lobs.put(lobId, in);
                 }
+            } else {
+                hmac = null;
+                in = lobs.get(lobId);
+                if (in == null) {
+                    throw DbException.get(ErrorCode.OBJECT_CLOSED);
+                }
+            }
             long offset = transfer.readLong();
             if (in.getPos() != offset) {
                 LobStorage lobStorage = session.getDataHandler().getLobStorage();
@@ -438,13 +456,30 @@ public class TcpServerThread implements Runnable {
             transfer.writeBoolean(true);
             Value[] v = result.currentRow();
             for (int i = 0; i < result.getVisibleColumnCount(); i++) {
+                if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_12) {
                     transfer.writeValue(v[i]);
+                } else {
+                    writeValue(v[i]);
+                }
             }
         } else {
             transfer.writeBoolean(false);
         }
     }
 
+    private void writeValue(Value v) throws IOException {
+        if (v.getType() == Value.CLOB || v.getType() == Value.BLOB) {
+            if (v instanceof ValueLobDb) {
+                ValueLobDb lob = (ValueLobDb) v;
+                if (lob.isStored()) {
+                    long id = lob.getLobId();
+                    lobs.put(id, new CachedInputStream(null));
+                }
+            }
+        }
+        transfer.writeValue(v);
+    }
+
     void setThread(Thread thread) {
         this.thread = thread;
     }

h2/src/main/org/h2/value/Transfer.java

@@ -21,6 +21,7 @@ import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Time;
 import java.sql.Timestamp;
+import java.util.Arrays;
 import org.h2.constant.ErrorCode;
 import org.h2.engine.Constants;
 import org.h2.engine.SessionInterface;
@@ -409,14 +410,16 @@ public class Transfer {
             writeString(v.getString());
             break;
         case Value.BLOB: {
-            if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+            if (version >= Constants.TCP_PROTOCOL_VERSION_11) {
                 if (v instanceof ValueLobDb) {
                     ValueLobDb lob = (ValueLobDb) v;
                     if (lob.isStored()) {
                         writeLong(-1);
                         writeInt(lob.getTableId());
                         writeLong(lob.getLobId());
+                        if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
                             writeBytes(calculateLobMac(lob.getLobId()));
+                        }
                         writeLong(lob.getPrecision());
                         break;
                     }
@@ -435,14 +438,16 @@ public class Transfer {
             break;
         }
         case Value.CLOB: {
-            if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+            if (version >= Constants.TCP_PROTOCOL_VERSION_11) {
                 if (v instanceof ValueLobDb) {
                     ValueLobDb lob = (ValueLobDb) v;
                     if (lob.isStored()) {
                         writeLong(-1);
                         writeInt(lob.getTableId());
-                        writeBytes(calculateLobMac(lob.getLobId()));
                         writeLong(lob.getLobId());
+                        if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+                            writeBytes(calculateLobMac(lob.getLobId()));
+                        }
                         writeLong(lob.getPrecision());
                         break;
                     }
@@ -573,11 +578,16 @@ public class Transfer {
             return ValueStringFixed.get(readString());
         case Value.BLOB: {
             long length = readLong();
-            if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+            if (version >= Constants.TCP_PROTOCOL_VERSION_11) {
                 if (length == -1) {
                     int tableId = readInt();
                     long id = readLong();
-                    byte[] hmac = readBytes();
+                    byte[] hmac;
+                    if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+                        hmac = readBytes();
+                    } else {
+                        hmac = null;
+                    }
                     long precision = readLong();
                     return ValueLobDb.create(Value.BLOB, session.getDataHandler().getLobStorage(), tableId, id, hmac, precision);
                 }
@@ -599,11 +609,16 @@ public class Transfer {
         }
         case Value.CLOB: {
             long length = readLong();
-            if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+            if (version >= Constants.TCP_PROTOCOL_VERSION_11) {
                 if (length == -1) {
                     int tableId = readInt();
                     long id = readLong();
-                    byte[] hmac = readBytes();
+                    byte[] hmac;
+                    if (version >= Constants.TCP_PROTOCOL_VERSION_12) {
+                        hmac = readBytes();
+                    } else {
+                        hmac = null;
+                    }
                     long precision = readLong();
                     return ValueLobDb.create(Value.CLOB, session.getDataHandler().getLobStorage(), tableId, id, hmac, precision);
                 }
@@ -712,11 +727,13 @@ public class Transfer {
     }
 
     /**
+     * Verify the HMAC.
+     *
      * @throws DbException if the HMAC does not verify
      */
     public void verifyLobMac(byte[] hmacData, long lobId) {
         byte[] result = calculateLobMac(lobId);
-        if (!result.equals(hmacData)) {
+        if (!Arrays.equals(result, hmacData)) {
             throw DbException.get(ErrorCode.REMOTE_CONNECTION_NOT_ALLOWED);
         }
     }
@@ -725,23 +742,10 @@ public class Transfer {
         if (lobMacSalt == null) {
             lobMacSalt = MathUtils.secureRandomBytes(LOB_MAC_SALT_LENGTH);
         }
-
-        byte[] hmacData = SHA256.getHashWithSalt(longToBytes(lobId), lobMacSalt);
-        return hmacData;
-    }
-
-    private static byte[] longToBytes(long src) {
         byte[] data = new byte[8];
-        data[0] = (byte) (src >> 56);
-        data[1] = (byte) (src >> 48);
-        data[2] = (byte) (src >> 40);
-        data[3] = (byte) (src >> 32);
-        data[4] = (byte) (src >> 24);
-        data[5] = (byte) (src >> 16);
-        data[6] = (byte) (src >> 8);
-        data[7] = (byte) src;
-        return data;
+        Utils.writeLong(data, 0, lobId);
+        byte[] hmacData = SHA256.getHashWithSalt(data, lobMacSalt);
+        return hmacData;
     }
 
-
 }