initial import

Change-Id: Ief25aef0066ea96bd2c329ccef974c072b3a5a73
diff --git a/of/lib/src/main/java/org/projectfloodlight/openflow/util/ChannelUtils.java b/of/lib/src/main/java/org/projectfloodlight/openflow/util/ChannelUtils.java
new file mode 100644
index 0000000..1a1ac6a
--- /dev/null
+++ b/of/lib/src/main/java/org/projectfloodlight/openflow/util/ChannelUtils.java
@@ -0,0 +1,80 @@
+package org.projectfloodlight.openflow.util;
+
+import java.util.List;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.projectfloodlight.openflow.exceptions.OFParseError;
+import org.projectfloodlight.openflow.protocol.OFMessageReader;
+import org.projectfloodlight.openflow.protocol.Writeable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.Charsets;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+
+/**
+ * Collection of helper functions for reading and writing into ChannelBuffers
+ *
+ * @author capveg
+ */
+
+public class ChannelUtils {
+    private static final Logger logger = LoggerFactory.getLogger(ChannelUtils.class);
+    public static String readFixedLengthString(ChannelBuffer bb, int length) {
+        byte[] dst = new byte[length];
+        bb.readBytes(dst, 0, length);
+        int validLength = 0;
+        for (validLength = 0; validLength < length; validLength++) {
+            if (dst[validLength] == 0)
+                break;
+        }
+        return new String(dst, 0, validLength, Charsets.US_ASCII);
+    }
+
+    public static void writeFixedLengthString(ChannelBuffer bb, String string,
+            int length) {
+        int l = string.length();
+        if (l > length) {
+            throw new IllegalArgumentException("Error writing string: length="
+                    + l + " > max Length=" + length);
+        }
+        bb.writeBytes(string.getBytes(Charsets.US_ASCII));
+        if (l < length) {
+            bb.writeZero(length - l);
+        }
+    }
+
+    static public byte[] readBytes(final ChannelBuffer bb, final int length) {
+        byte byteArray[] = new byte[length];
+        bb.readBytes(byteArray);
+        return byteArray;
+    }
+
+    static public void writeBytes(final ChannelBuffer bb,
+            final byte byteArray[]) {
+        bb.writeBytes(byteArray);
+    }
+
+    public static <T> List<T> readList(ChannelBuffer bb, int length, OFMessageReader<T> reader) throws OFParseError {
+        int end = bb.readerIndex() + length;
+        Builder<T> builder = ImmutableList.<T>builder();
+        if(logger.isTraceEnabled())
+            logger.trace("readList(length={}, reader={})", length, reader.getClass());
+        while(bb.readerIndex() < end) {
+            T read = reader.readFrom(bb);
+            if(logger.isTraceEnabled())
+                logger.trace("readList: read={}, left={}", read, end - bb.readerIndex());
+            builder.add(read);
+        }
+        if(bb.readerIndex() != end) {
+            throw new IllegalStateException("Overread length: length="+length + " overread by "+ (bb.readerIndex() - end) + " reader: "+reader);
+        }
+        return builder.build();
+    }
+
+    public static void writeList(ChannelBuffer bb, List<? extends Writeable> writeables) {
+        for(Writeable w: writeables)
+            w.writeTo(bb);
+    }
+}