[Emu] [ONOS-2600] Implement Basic BGP Update protocol message parsing and decode excluding path attributes.
Change-Id: I37ed38cb79583fbbb31057dafc06df245aef3c49
diff --git a/bgp/bgpio/src/main/java/org/onosproject/bgpio/protocol/ver4/BgpUpdateMsgVer4.java b/bgp/bgpio/src/main/java/org/onosproject/bgpio/protocol/ver4/BgpUpdateMsgVer4.java
new file mode 100644
index 0000000..9f4cf9b
--- /dev/null
+++ b/bgp/bgpio/src/main/java/org/onosproject/bgpio/protocol/ver4/BgpUpdateMsgVer4.java
@@ -0,0 +1,285 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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.onosproject.bgpio.protocol.ver4;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.onlab.packet.IpPrefix;
+import org.onosproject.bgpio.exceptions.BGPParseException;
+import org.onosproject.bgpio.protocol.BGPMessageReader;
+import org.onosproject.bgpio.protocol.BGPType;
+import org.onosproject.bgpio.protocol.BgpUpdateMsg;
+import org.onosproject.bgpio.types.BGPErrorType;
+import org.onosproject.bgpio.types.BGPHeader;
+import org.onosproject.bgpio.util.Validation;
+import org.onosproject.bgpio.protocol.BGPVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * BGP Update Message: UPDATE messages are used to transfer routing information
+ * between BGP peers. The information in the UPDATE message is used by core to
+ * construct a graph
+ */
+public class BgpUpdateMsgVer4 implements BgpUpdateMsg {
+
+ /* 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | |
+ + +
+ | |
+ + +
+ | Marker |
+ + +
+ | |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Length | Type |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Withdrawn Routes Length (2 octets) |
+ +-----------------------------------------------------+
+ | Withdrawn Routes (variable) |
+ +-----------------------------------------------------+
+ | Total Path Attribute Length (2 octets) |
+ +-----------------------------------------------------+
+ | Path Attributes (variable) |
+ +-----------------------------------------------------+
+ | Network Layer Reachability Information (variable) |
+ +-----------------------------------------------------+
+ REFERENCE : RFC 4271
+ */
+
+ protected static final Logger log = LoggerFactory
+ .getLogger(BgpUpdateMsgVer4.class);
+
+ public static final byte PACKET_VERSION = 4;
+ //Withdrawn Routes Length(2) + Total Path Attribute Length(2)
+ public static final int PACKET_MINIMUM_LENGTH = 4;
+ public static final int BYTE_IN_BITS = 8;
+ public static final int MIN_LEN_AFTER_WITHDRW_ROUTES = 2;
+ public static final int MINIMUM_COMMON_HEADER_LENGTH = 19;
+ public static final BGPType MSG_TYPE = BGPType.UPDATE;
+ public static final BgpUpdateMsgVer4.Reader READER = new Reader();
+
+ private List<IpPrefix> withdrawnRoutes;
+ private BgpPathAttributes bgpPathAttributes;
+ private BGPHeader bgpHeader;
+ private List<IpPrefix> nlri;
+
+ /**
+ * Constructor to initialize parameters for BGP Update message.
+ *
+ * @param bgpHeader in Update message
+ * @param withdrawnRoutes withdrawn routes
+ * @param bgpPathAttributes BGP Path attributes
+ * @param nlri Network Layer Reachability Information
+ */
+ public BgpUpdateMsgVer4(BGPHeader bgpHeader, List<IpPrefix> withdrawnRoutes,
+ BgpPathAttributes bgpPathAttributes, List<IpPrefix> nlri) {
+ this.bgpHeader = bgpHeader;
+ this.withdrawnRoutes = withdrawnRoutes;
+ this.bgpPathAttributes = bgpPathAttributes;
+ this.nlri = nlri;
+ }
+
+ /**
+ * Reader reads BGP Update Message from the channel buffer.
+ */
+ static class Reader implements BGPMessageReader<BgpUpdateMsg> {
+
+ @Override
+ public BgpUpdateMsg readFrom(ChannelBuffer cb, BGPHeader bgpHeader)
+ throws BGPParseException {
+
+ if (cb.readableBytes() != (bgpHeader.getLength() - MINIMUM_COMMON_HEADER_LENGTH)) {
+ Validation.validateLen(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.BAD_MESSAGE_LENGTH, bgpHeader.getLength());
+ }
+
+ LinkedList<IpPrefix> withDrwRoutes = new LinkedList<>();
+ LinkedList<IpPrefix> nlri = new LinkedList<>();
+ BgpPathAttributes bgpPathAttributes = new BgpPathAttributes();
+ // Reading Withdrawn Routes Length
+ Short withDrwLen = cb.readShort();
+
+ if (cb.readableBytes() < withDrwLen) {
+ Validation.validateLen(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.MALFORMED_ATTRIBUTE_LIST,
+ cb.readableBytes());
+ }
+ ChannelBuffer tempCb = cb.readBytes(withDrwLen);
+ if (withDrwLen != 0) {
+ // Parsing WithdrawnRoutes
+ withDrwRoutes = parseWithdrawnRoutes(tempCb);
+ }
+ if (cb.readableBytes() < MIN_LEN_AFTER_WITHDRW_ROUTES) {
+ log.debug("Bgp Path Attribute len field not present");
+ throw new BGPParseException(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.MALFORMED_ATTRIBUTE_LIST, null);
+ }
+
+ // Reading Total Path Attribute Length
+ short totPathAttrLen = cb.readShort();
+ int len = withDrwLen + totPathAttrLen + PACKET_MINIMUM_LENGTH;
+ if (len > bgpHeader.getLength()) {
+ throw new BGPParseException(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.MALFORMED_ATTRIBUTE_LIST, null);
+ }
+ if (totPathAttrLen != 0) {
+ // Parsing BGPPathAttributes
+ if (cb.readableBytes() < totPathAttrLen) {
+ Validation
+ .validateLen(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.MALFORMED_ATTRIBUTE_LIST,
+ cb.readableBytes());
+ }
+ tempCb = cb.readBytes(totPathAttrLen);
+ bgpPathAttributes = BgpPathAttributes.read(tempCb);
+ }
+ if (cb.readableBytes() > 0) {
+ // Parsing NLRI
+ nlri = parseNlri(cb);
+ }
+ return new BgpUpdateMsgVer4(bgpHeader, withDrwRoutes,
+ bgpPathAttributes, nlri);
+ }
+ }
+
+ /**
+ * Parses NLRI from channel buffer.
+ *
+ * @param cb channelBuffer
+ * @return list of IP Prefix
+ * @throws BGPParseException while parsing NLRI
+ */
+ public static LinkedList<IpPrefix> parseNlri(ChannelBuffer cb)
+ throws BGPParseException {
+ LinkedList<IpPrefix> nlri = new LinkedList<>();
+ while (cb.readableBytes() > 0) {
+ int length = cb.readByte();
+ IpPrefix ipPrefix;
+ if (length == 0) {
+ byte[] prefix = new byte[] {0};
+ ipPrefix = Validation.bytesToPrefix(prefix, length);
+ nlri.add(ipPrefix);
+ } else {
+ int len = length / BYTE_IN_BITS;
+ int reminder = length % BYTE_IN_BITS;
+ if (reminder > 0) {
+ len = len + 1;
+ }
+ if (cb.readableBytes() < len) {
+ Validation.validateLen(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.MALFORMED_ATTRIBUTE_LIST,
+ cb.readableBytes());
+ }
+ byte[] prefix = new byte[len];
+ cb.readBytes(prefix, 0, len);
+ ipPrefix = Validation.bytesToPrefix(prefix, length);
+ nlri.add(ipPrefix);
+ }
+ }
+ return nlri;
+ }
+
+ /**
+ * Parsing withdrawn routes from channel buffer.
+ *
+ * @param cb channelBuffer
+ * @return list of IP prefix
+ * @throws BGPParseException while parsing withdrawn routes
+ */
+ public static LinkedList<IpPrefix> parseWithdrawnRoutes(ChannelBuffer cb)
+ throws BGPParseException {
+ LinkedList<IpPrefix> withDrwRoutes = new LinkedList<>();
+ while (cb.readableBytes() > 0) {
+ int length = cb.readByte();
+ IpPrefix ipPrefix;
+ if (length == 0) {
+ byte[] prefix = new byte[] {0};
+ ipPrefix = Validation.bytesToPrefix(prefix, length);
+ withDrwRoutes.add(ipPrefix);
+ } else {
+ int len = length / BYTE_IN_BITS;
+ int reminder = length % BYTE_IN_BITS;
+ if (reminder > 0) {
+ len = len + 1;
+ }
+ if (cb.readableBytes() < len) {
+ Validation
+ .validateLen(BGPErrorType.UPDATE_MESSAGE_ERROR,
+ BGPErrorType.MALFORMED_ATTRIBUTE_LIST,
+ cb.readableBytes());
+ }
+ byte[] prefix = new byte[len];
+ cb.readBytes(prefix, 0, len);
+ ipPrefix = Validation.bytesToPrefix(prefix, length);
+ withDrwRoutes.add(ipPrefix);
+ }
+ }
+ return withDrwRoutes;
+ }
+
+ @Override
+ public BGPVersion getVersion() {
+ return BGPVersion.BGP_4;
+ }
+
+ @Override
+ public BGPType getType() {
+ return BGPType.UPDATE;
+ }
+
+ @Override
+ public void writeTo(ChannelBuffer channelBuffer) throws BGPParseException {
+ //Not to be implemented as of now
+ }
+
+ @Override
+ public BgpPathAttributes bgpPathAttributes() {
+ return this.bgpPathAttributes;
+ }
+
+ @Override
+ public List<IpPrefix> withdrawnRoutes() {
+ return withdrawnRoutes;
+ }
+
+ @Override
+ public List<IpPrefix> nlri() {
+ return nlri;
+ }
+
+ @Override
+ public BGPHeader getHeader() {
+ return this.bgpHeader;
+ }
+
+ @Override
+ public String toString() {
+ return MoreObjects.toStringHelper(getClass())
+ .omitNullValues()
+ .add("bgpHeader", bgpHeader)
+ .add("withDrawnRoutes", withdrawnRoutes)
+ .add("nlri", nlri)
+ .add("bgpPathAttributes", bgpPathAttributes)
+ .toString();
+ }
+}