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/*
* 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| Withdrawn Routes Length (2 octets) |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| Withdrawn Routes (variable) |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();
}
}
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