I am selecting a language to write a cross-platform networking library that my project needs. But a simple test shows mono may not support ipv6 socket.
Socket s;
try
{
s = new Socket(AddressFamily.InterNetworkV6, SocketType.Dgram, ProtocolType.Udp);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
The above code runs fine in Windows under .net. But throws an exception when using mono VM. Does anyone know if mono supports ipv6 sockets?
Related
I have recently developed a small client server application for a customer. A windows executable adaptor provides a number of TCP sockets to interact with an external host, and my java(kotlin) client software is listening to those sockets and sends commands when necessary. Nothing fancy, and I tested the application thoroughly on my Windows10 developer system.
Now I tried to migrate the software to Ubuntu 22 as a host. The windows executable is running on wine emulation and I have checked with netstat that it listens to the expected ports, also I tested with telnet to access the primary port, and I can receive the feed. But when I try to access the ports from the java client, my code throws ChannelClosedException whenever my code tries to open the connection, and the retry logic (spring-retry) is repeating this 10 times before giving up:
Caused by: java.nio.channels.ClosedChannelException: null
at java.base/sun.nio.ch.UnixAsynchronousSocketChannelImpl.implConnect(UnixAsynchronousSocketChannelImpl.java:301) ~[na:na]
at java.base/sun.nio.ch.AsynchronousSocketChannelImpl.connect(AsynchronousSocketChannelImpl.java:200) ~[na:na]
Here some excerpt from the code I execute:
class RequestHandler(private val hostAddress: InetSocketAddress) :
Runnable{
private val client: AsynchronousSocketChannel = AsynchronousSocketChannel.open()
#Retryable(value=[ConnectException::class, ClosedChannelException::class], maxAttempts = 10)
fun init() {
connect()
executor.submit(this)
}
private fun connect() {
try {
client.connect(hostAddress).get()
client.setOption(StandardSocketOptions.TCP_NODELAY, true)
client.setOption(StandardSocketOptions.SO_KEEPALIVE, true)
} catch (e: RuntimeException) {
logger.error("Failed to connect to $hostAddress due to ${e.localizedMessage}")
}
}
}
Do you see anything here that requires special attention on a Linux host?
I am porting an android app to javaFX for windows deployment, i'm new to javaFX and desktop deployment, but not so new to java.
The app contains a WebView that loads a url obtained from a server via Json (so could be essentially anything).
openJDK 14 , openJfx 16, intellij idea ultimate 2021.1.3, gradle: plugins: org.beryx.jlink & org.openjfx.javafxplugin
This works fine when I run the program in development and testing (on a windows 10 machine), but when it is packaged and deployed on a windows machine (any windows 10 so far) I get an "java.lang.Throwable: SSL handshake failed" exception when the page is loaded.
This is the stack trace:
[ERROR] 2021-07-14 14:13:53.737 [JavaFX Application Thread] MediaElementWeb - WebView Failed:
java.lang.Throwable: SSL handshake failed
at javafx.scene.web.WebEngine$LoadWorker.describeError(WebEngine.java:1440) ~[javafx.web:?]
at javafx.scene.web.WebEngine$LoadWorker.dispatchLoadEvent(WebEngine.java:1379) ~[javafx.web:?]
at javafx.scene.web.WebEngine$PageLoadListener.dispatchLoadEvent(WebEngine.java:1240) ~[javafx.web:?]
at com.sun.webkit.WebPage.fireLoadEvent(WebPage.java:2524) ~[javafx.web:?]
at com.sun.webkit.WebPage.fwkFireLoadEvent(WebPage.java:2369) ~[javafx.web:?]
at com.sun.webkit.network.URLLoaderBase.twkDidFail(Native Method) ~[javafx.web:?]
at com.sun.webkit.network.URLLoader.notifyDidFail(URLLoader.java:799) ~[javafx.web:?]
at com.sun.webkit.network.URLLoader.lambda$didFail$6(URLLoader.java:782) ~[javafx.web:?]
at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:447) ~[javafx.graphics:?]
at java.security.AccessController.doPrivileged(AccessController.java:391) ~[?:?]
at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:446) ~[javafx.graphics:?]
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96) ~[javafx.graphics:?]
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) ~[javafx.graphics:?]
at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174) ~[javafx.graphics:?]
at java.lang.Thread.run(Thread.java:832) [?:?]
The problem is not specific to any particular certificate, so I know it is not a problem specifically with the certificate generally, tested with many sites. and I ONLY get this error in the deployed app.
The page is being loaded in a standard way: WebEngine.load(targetURL);
I am capturing the error with:
tNode.getEngine().getLoadWorker().stateProperty().addListener((o, ov, nv) -> {
if (nv == Worker.State.FAILED) {
logger.error("WebView Failed: ", tNode.getEngine().getLoadWorker().getException());
}
});
I have searched and tried solutions offered by other people that seem to have experienced similar errors, such as:
Setting a trust manager before calling load(page):
TrustManager[] trustAllCerts = new TrustManager[] {
new X509TrustManager() {
public java.security.cert.X509Certificate[] getAcceptedIssuers() {
return null;
}
public void checkClientTrusted(
java.security.cert.X509Certificate[] certs, String authType) {
}
public void checkServerTrusted(
java.security.cert.X509Certificate[] certs, String authType) {
}
}
};
// Install the all-trusting trust manager
try {
SSLContext sc = SSLContext.getInstance("SSL");
sc.init(null, trustAllCerts, new java.security.SecureRandom());
HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
} catch (GeneralSecurityException e) {
logger.error("SSLContext Failed: ", e);
}
(No errors or effect here)
and
settings the JVMarg on the deployment
-Dcom.sun.webkit.useHTTP2Loader=false
Which I can see has the effect of "com.sun.webkit.network.URLLoader" being shown in the stack trace instead of http2 (as was suggested on other threads) but also no change here either.
Has anyone any thoughts (bearing in mind I'm a novice at java desktop deployment) at what the issue can be and how to resolve it?
Many thanks
Update:
Trace from console on deployed test https://pastebin.com/R5SkR4w1
First few rows:
javax.net.ssl|WARNING|2C|URL-Loader-1|2021-07-15 10:46:45.991 BST|SignatureScheme.java:295|Signature algorithm, ed25519, is not supported by the underlying providers
javax.net.ssl|WARNING|2C|URL-Loader-1|2021-07-15 10:46:45.992 BST|SignatureScheme.java:295|Signature algorithm, ed448, is not supported by the underlying providers
javax.net.ssl|WARNING|2C|URL-Loader-1|2021-07-15 10:46:45.995 BST|NamedGroup.java:297|No AlgorithmParameters for x25519 (
"throwable" : {
java.security.NoSuchAlgorithmException: Algorithm x25519 not available
at java.base/javax.crypto.KeyAgreement.getInstance(KeyAgreement.java:192)
at java.base/sun.security.ssl.NamedGroup.<init>(NamedGroup.java:286)
at java.base/sun.security.ssl.NamedGroup.<clinit>(NamedGroup.java:184)
at java.base/sun.security.ssl.SignatureScheme.<clinit>(SignatureScheme.java:59)
at java.base/sun.security.ssl.SSLSessionImpl.<clinit>(SSLSessionImpl.java:823)
at java.base/sun.security.ssl.TransportContext.<init>(TransportContext.java:133)
at java.base/sun.security.ssl.TransportContext.<init>(TransportContext.java:103)
at java.base/sun.security.ssl.SSLSocketImpl.<init>(SSLSocketImpl.java:111)
at java.base/sun.security.ssl.SSLSocketFactoryImpl.createSocket(SSLSocketFactoryImpl.java:72)
at java.base/sun.net.www.protocol.https.HttpsClient.createSocket(HttpsClient.java:413)
at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:162)
at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:474)
at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:569)
at java.base/sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:265)
at java.base/sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:372)
at ...
Managed to solve this with helpful comments from #slaw about a suggestion I had tried initially, but ultimately not implemented correctly, and help from #dave_thompson_085 with how to provide extra debugging info. So the resolution, and a few tips for people in the same boat:
1. The solution:
The Badass Jlink Plugin for gradle on Intellij IDEA, for Java 14 and JavaFX 16 was not correctly merging the security provider classes.
This was resolved by adding "jdk.crypto.ec" to the merged modules list.
2. Adding the module manually
The org.beryx.jlink plugin (2.24.0) is really complex and powerful, so it was a struggle to work out how to do it with my implementation.
I tried many combinations, but the following code did it for me in my build.gradle:
jlink {
//... Other jlink \ jpackage stuff
mergedModule {
additive = true
requires 'jdk.crypto.ec'
}
//... Other jlink \ jpackage stuff
}
3. Debugging packaged java binary for windows
Some Jlink config changes that helped along the way.
jlink {
//..
jpackage {
//..
imageOptions = [
"--win-console"
]
}
//..
launcher {
jvmArgs = ['-Dcom.sun.webkit.useHTTP2Loader=false','-Djavax.net.debug=ssl:handshake']
}
}
--win-console opens a console window when you start your program so you can see the logging out put
-Djavax.net.debug=ssl:handshake gives more information about the SSL process and handshaking so you can see what is happening.
My friend has a problem with connection to rabbitmq via docker toolbox.
The whole team uses windows pro or edu, where we don't have any problems with docker. But one of my friend has windows home, so we needed to download docker toolbox. When we open rabbitmq management, it works well, but when we try to connect to rabbit, we get error message: "refuse to connect".
public void startRabbitMQ() {
ConnectionFactory factory = new ConnectionFactory();
setSpecificationFactory(factory);
try {
connection = factory.newConnection();
} catch (IOException | TimeoutException e) {
e.printStackTrace();
}
try {
channel = Objects.requireNonNull(connection).createChannel();
} catch (IOException e) {
e.printStackTrace();
}
}
private void setSpecificationFactory(ConnectionFactory factory){
factory.setUsername("guest");
factory.setPassword("guest");
factory.setVirtualHost("/");
factory.setHost("localhost");
factory.setPort(5672);
}
We all use this code to connect, and, as I said, it works well. We think that it is a problem with the line:"factory.setHost([...])"
We all need only connect with localhost, but when we connect via docker toolbox we try many different options like:
localhost,
192.168.99.101,
127.0.0.1
With docker toolbox we need to use different IP, which is shared for us from kitematic, like on SS below, so we tried 192.168.99.101, but still it didn't work.
As I said, rabbitmq management works properly. We just used chrome and open "192.168.99.101:15672".
We tried
shut down antivirus and firewall
check, if port is used
virtualization is enabled
Docker toolbox kitematic
I'm using Sap Jco to connect to SAP database with the front end being Java(JSF), When I connect to SAP with:
try {
mConnection =JCO.createClient("400", // SAP client
"c3026902", // userid
"********", // password
"EN", // language
"iwdf5020", // host name
"00"); // system number
mConnection.connect();
}
catch (Exception ex) {
ex.printStackTrace();
System.exit(1);
}
Problem I'm facing is when run the application for the first time, data is displayed but when I re-run it says "Could not load middleware layer 'com.sap.mw.jco.rfc.MiddlewareRFC' "
Can any one help me in resolving the issue?????
This sounds like the API cannot load the native driver files.
The SAP Java Connector consists of a native runtime part, that does the actuall communication and a Java API that wraps this functionality with a java api.
The Java API is inside the sapjco.jar and the native drivers are e.g on windows inside librfc32.dll and sapjcorfc.dll.
Place these dll's into your system path (e.g. windows: C:\WiNDOWS\system32) and it should run.
Cheers
Sebastian
Are your DLLs located in the Windows system32 folder? If so, are you probably using the wrong architecture? (x64 DLL on 32 bit or vice versa)
Also, are the DLLs the same version as the java api? If you have SAP GUI installed there could be older DLLs around.
Defining SAP connection:
For the Version 3,0 of the sapjco library there exists plenty of useful information. To create a connection following the instructions in:
http://www.browseye.com/linkShare.html?url=http://help.sap.com/saphelp_nwpi711/helpdata/en/46/fb807cc7b46c30e10000000a1553f7/content.htm?bwsCriterion=%22Setting%20Up%20Connection%22&bwsMatch=1&bwsCriterion=%22Setting%20Up%20Connection%22&bwsMatch=1
There are a few thing that you should take into account:
Place the dll file in the same place that the jar.
The dll must be the right version for your operating system and architecture otherwise you will get a native library error.
Example of code to create a connection to the server.
public class StepByStepClient
{
static String DESTINATION_NAME1 = "ABAP_AS_WITHOUT_POOL";
static String DESTINATION_NAME2 = "ABAP_AS_WITH_POOL";
static
{
Properties connectProperties = new Properties();
connectProperties.setProperty(DestinationDataProvider.JCO_ASHOST, "ls4065");
connectProperties.setProperty(DestinationDataProvider.JCO_SYSNR, "85");
connectProperties.setProperty(DestinationDataProvider.JCO_CLIENT, "800");
connectProperties.setProperty(DestinationDataProvider.JCO_USER, "homofarber");
connectProperties.setProperty(DestinationDataProvider.JCO_PASSWD, "laska");
connectProperties.setProperty(DestinationDataProvider.JCO_LANG, "en");
createDestinationDataFile(DESTINATION_NAME1, connectProperties);
connectProperties.setProperty(DestinationDataProvider.JCO_POOL_CAPACITY, "3");
connectProperties.setProperty(DestinationDataProvider.JCO_PEAK_LIMIT, "10");
createDestinationDataFile(DESTINATION_NAME2, connectProperties);
}
static void createDestinationDataFile(String destinationName, Properties connectProperties)
{
File destCfg = new File(destinationName+".jcoDestination");
try
{
FileOutputStream fos = new FileOutputStream(destCfg, false);
connectProperties.store(fos, "for tests only !");
fos.close();
}
catch (Exception e)
{
throw new RuntimeException("Unable to create the destination files", e);
}
}
public static void step1Connect() throws JCoException
{
JCoDestination destination = JCoDestinationManager.getDestination(DESTINATION_NAME1);
System.out.println("Attributes:");
System.out.println(destination.getAttributes());
System.out.println();
}
}
In SAPJco 3.0 connections are build from the info contained in a “Destination”.
The documentation example use a properties file to save the “Destination”. However it is a non-secure way to keep connection info. As is indicated on the documentation in the hightlighted paragraph you can see on next link.
http://help.sap.com/saphelp_nwpi711/helpdata/en/48/5fb9f9b523501ee10000000a421937/content.htm?bwsCriterion=%22In%20practice%20you%20should%20avoid%20this%20for%20security%20reasons.%22&bwsMatch=1
You can keep connection info on a database or any other storage system if you create a custom “DestinationDataProvider” In the Examples provided with the SAPJco library there is an example of how to create a custom DestinationDataProvider.
Given:
- the application - desktop GUI (WPF) .NET app
- windows service watching for application (.NET also)
The windows service periodically "pings" application to get sure it's healthy (and if it's not winservice will restart it).
I was going to implement "pinging" via named pipes. To make things simpler I decided to do it with WCF. The application hosts a WCF-service (one operation Ping returning something). The windows service is a client for this WCF-service, invokes it periodically based on a timer.
That's all in Windows 7.
Windows service is running under LocalService (in session#0).
Desktop application is running under currently logged in user (in session#1).
The problem:
Windows service can't see WCF endpoint (with NetNamedPipeBinding) created in and being listened in desktop application. That means that on call via wcf proxy I get this exception: "The pipe endpoint 'net.pipe://localhost/HeartBeat' could not be found on your local machine"
I'm sure code is ok, because another desktop application (in session#1) can see the endpoint.
Obviously here I'm dealing with some security stuff for Win32 system object isolation.
But I believe there should be a way to workaround restrictions I've encountered with.
I can sacrifice WCF approach and go the raw NamedPipe way.
An easier solution might be to use a WCF duplex contract with the Windows service hosting the WCF service. The client App would call an operation on the service to register itself, when it starts up. The Ping would then be an operation invoked periodically by the service on the client's callback contract, to which the App would respond.
Service visibility works this way round, because the Windows service can run with SeCreateGlobalPrivilege, and so the shared memory object via which the pipe name is published by the service can be created in the Global kernel namespace, visible to other sessions. Interactive applications can't easily get that privilege in Windows7, so WCF services in such applications fall back to publishing the pipe in the Local kernel namespace, visible only within their own session.
Finally I've found a solution - using Named Pipes from System.IO.Pipes directly. It's seems that WCF's pipes support implementation doesn't use System.IO.Pipes.
Server:
using (var pipeServer = new NamedPipeServerStream("mypipe", PipeDirection.Out, 1))
{
try
{
while (true)
{
// #1 Connect:
try
{
pipeServer.WaitForConnection();
}
catch (ObjectDisposedException)
{
yield break;
}
if (ae.IsCanceled())
return;
// #2: Sending response:
var response = Encoding.ASCII.GetBytes(DateTime.Now.ToString());
try
{
pipeServer.Write(response, 0, response.Length);
}
catch (ObjectDisposedException)
{
return;
}
// #3: Disconnect:
pipeServer.Disconnect();
}
}
finally
{
if (pipeServer.IsConnected)
pipeServer.Disconnect();
}
}
Client:
using (var pipeClient = new NamedPipeClientStream(".", "mypipe", PipeDirection.In))
{
try
{
try
{
pipeClient.Connect(TIMEOUT);
}
catch(TimeoutException ex)
{
// nobody answers to us
continue;
}
using (var sr = new StreamReader(pipeClient))
{
string temp;
while ((temp = sr.ReadLine()) != null)
{
// got response
}
}
}
catch(Exception ex)
{
// pipe error
throw;
}
}