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https://issues.apache.org/jira/browse/SSHD-1295?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17603622#comment-17603622
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Thomas Wolf commented on SSHD-1295:
-----------------------------------
I see a similar question regarding {{ConnectFuture.cancel()}} was already
posted in SSHD-1280.
For cancellation, I think the expectations for {{cancel()}} are quite obvious:
* If a value is already set on the future (session or exception), {{cancel()}}
does nothing.
* Otherwise it fulfills the future with a "cancelled" marker.
** If there is some asynchronous operation going on for that future, that
operation should be cancelled.
** If that operation cannot be cancelled:
*** If it terminates successfully, behavior may be different depending on what
kind of future it is:
**** A {{ConnectFuture}} must close the connection/session, otherwise there is
a stale connection the user cannot close using up one socket.
**** An {{AuthFuture}} may result in the session being authenticated even if
it was cancelled.
*** If it terminates unsuccessfully, nothing needs to be done.
For time-outs the question is more difficult to answer if several threads are
allowed to call {{{}verify(){}}}. Here, SSHD-1278 is directly related.
> Connection attempt not canceled when a connection timeout occurs
> ----------------------------------------------------------------
>
> Key: SSHD-1295
> URL: https://issues.apache.org/jira/browse/SSHD-1295
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 2.9.2
> Reporter: Thomas Wolf
> Priority: Major
>
> This is not a new bug; it's also present in earlier versions.
> When {{client.connect().verify(timeout)}} times out, the underlying
> asynchronous connection attempt still continues _and may still succeed_. If
> that happens, there is a connection and session that the user cannot use or
> close. (Short of calling verify().getSession() again, but that is a pattern I
> have never seen, and it also makes using a timeout rather useless.)
> This means that timeouts are inherently unreliable.
> Here's a simple test case illustrating this problem (for
> {{org.apache.sshd.client.ClientTest}}):
> {code:java}
> @Test
> public void testConnectTimeout() throws Exception {
> client.start();
> try {
> ConnectFuture future = client.connect(getCurrentTestName(),
> TEST_LOCALHOST, port);
> try {
> future.verify(1);
> fail("Timeout expected");
> } catch (InterruptedIOException | SshException e) {
> ClientSession session = null;
> try {
> session = future.verify(CONNECT_TIMEOUT).getSession();
> } catch (SshException e2) {
> assertTrue("Expected a timeout, got " + e2,
> e2.getMessage().contains("timeout"));
> }
> if (session != null) {
> assertTrue("Session should be closed", session.isClosed() ||
> session.isClosing());
> }
> }
> } finally {
> client.stop();
> }
> }
> {code}
> This test fails.
> When the {{ConnectFuture}} times out (or is canceled, or waiting is
> interrupted), the underlying {{IoConnectFuture}} must be canceled. If we do
> get an {{IoSession}} all the same, but the {{ConnectFuture}} is already
> canceled or timed out, the {{IoSession}} must be closed immediately.
> Preferrably before a {{Session}} is created at all; otherwise, that SSH
> session must be closed, too. Creating a {{ClientSession}} already starts the
> application-level protocol (sending the SSH ident, or if a proxy is used, the
> proxy connect request).
> The test also highlights another problem: there is no clear indication that
> the failure of {{verify()}} indicates a timeout. Probably there should be a
> dedicated exception for this, or at least the {{SshException}} should have a
> {{TimeoutException}} as cause.
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