我们的网络管理中心作为管理中心,是服务端!各个被管设备通过交换机作为客户端与网管中心进行通信,使用的TCP/IP协议!
SNMP只是一种协议包,SNMP4J作为SNMP使用的Java工具包,提供了方便安全的工具包功能!
但是在使用中发现一个问题就是,服务端与客户端发送消息时,发送数次后就不再发送数据了!网络抓包也抓不到,跟踪断点到SNMP4J的代码中发现了这样一个问题!
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/**
* Sends a SNMP message to the supplied address.
*
* @param address
* an <code>TcpAddress</code>. A
* <code>ClassCastException</code> is thrown if
* <code>address</code> is not a <code>TcpAddress</code>
* instance.
* @param message
* byte[] the message to sent.
* @throws IOException
*/
public void sendMessage(Address address, byte [] message)
throws java.io.IOException {
if (server == null ) {
listen();
}
serverThread.sendMessage(address, message);
}
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我们可以看到,他与UDP的不同是,使用了一个服务的线程!
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public void sendMessage(Address address, byte [] message)
throws java.io.IOException {
Socket s = null ;
SocketEntry entry = (SocketEntry) sockets.get(address);
if (logger.isDebugEnabled()) {
logger.debug( "Looking up connection for destination '"
+ address + "' returned: " + entry);
logger.debug(sockets.toString());
}
if (entry != null ) {
s = entry.getSocket();
}
if ((s == null ) || (s.isClosed()) || (!s.isConnected())) {
if (logger.isDebugEnabled()) {
logger.debug( "Socket for address '" + address
+ "' is closed, opening it..." );
}
pending.remove(entry);
SocketChannel sc = null ;
try {
// Open the channel, set it to non-blocking, initiate
// connect
sc = SocketChannel.open();
sc.configureBlocking( false );
sc
.connect( new InetSocketAddress(
((TcpAddress) address).getInetAddress(),
((TcpAddress) address).getPort()));
s = sc.socket();
entry = new SocketEntry((TcpAddress) address, s);
entry.addMessage(message);
sockets.put(address, entry);
synchronized (pending) {
pending.add(entry);
}
selector.wakeup();
logger.debug( "Trying to connect to " + address);
} catch (IOException iox) {
logger.error(iox);
throw iox;
}
} else {
entry.addMessage(message);
synchronized (pending) {
pending.add(entry);
}
selector.wakeup();
}
}
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他从一个Map中去获得连接 SocketEntry ,然后得到连接对象Socket!
判断Socket是否有效,有效则直接发送,无效则创建连接后再发送!
然后我找到这样一段代码
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private synchronized void timeoutSocket(SocketEntry entry) {
if (connectionTimeout > 0 ) {
socketCleaner.schedule( new SocketTimeout(entry), connectionTimeout);
}
}
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也就是说服务端会自己检查的连接并且去清除他!
我尝试设置 connectionTimeout 的值
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private void init() throws UnknownHostException, IOException {
threadPool = ThreadPool.create( "Trap" , 2 );
dispatcher = new MultiThreadedMessageDispatcher(threadPool, new MessageDispatcherImpl());
// 本地IP与监听端口
listenAddress = GenericAddress.parse(System.getProperty( "snmp4j.listenAddress" , "tcp:192.168.9.69/5055" ));
DefaultTcpTransportMapping transport;
transport = new DefaultTcpTransportMapping((TcpAddress) listenAddress);
transport.setConnectionTimeout( 0 );
snmp = new Snmp(dispatcher, transport);
snmp.getMessageDispatcher().addMessageProcessingModel( new MPv1());
snmp.getMessageDispatcher().addMessageProcessingModel( new MPv2c());
snmp.getMessageDispatcher().addMessageProcessingModel( new MPv3());
USM usm = new USM(SecurityProtocols.getInstance(), new OctetString(MPv3.createLocalEngineID()), 0 );
SecurityModels.getInstance().addSecurityModel(usm);
snmp.listen();
}
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增加一行代码 设置DefaultTcpTransportMapping的超时时间是 0 !
然后就没有问题了!
虽然临时解决了问题,但是由于对SNMP4J不够深入了解,我怕问题恐怕不是这样的!
我在此也希望使用SNMP4J为工具,且作为服务端,在发送数据时有问题的解决方法!
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://www.iteye.com/blog/cuisuqiang-1685183