[jira] [Updated] (IGNITE-21603) Incorrect backward connection check with loopback address.

["Vladimir Steshin (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-21603?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vladimir Steshin updated IGNITE-21603:
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    Summary: Incorrect backward connection check with loopback address.  (was: Incorrect backward connection chech with loopback address.)

> Incorrect backward connection check with loopback address.
> ----------------------------------------------------------
>
>                 Key: IGNITE-21603
>                 URL: https://issues.apache.org/jira/browse/IGNITE-21603
>             Project: Ignite
>          Issue Type: Bug
>            Reporter: Vladimir Steshin
>            Assignee: Vladimir Steshin
>            Priority: Minor
>              Labels: ise
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> We may skip backward connection check to a previous node if it has the same loopback address as the current node.
> Consider:
> # Neither _IgniteConfiguration#setLocalHost()_ or _TcpDiscoverySpi#setLocalAddress()_ is set. Or the localhost parameter is set to "_0.0.0.0_". 
> # Nodes start on different hosts. All the available host addresses are resolved and
> # Among the other addresses, all nodes get the loopback address "127.0.0.1:47500" (47500 is the default tcp discovery port).
> # Cluster starts and works. But 
> # Some node N (A) decides the connection to node N+1 (B) is lost and tries to connect to node N+2 (C) and sends _TcpDiscoveryHandshakeRequest_.
> # Before C accepts incoming A's connection, it decides to check B and pings it with _ServerImpl#checkConnection(List<InetSocketAddress> addrs, int timeout)_
> # Around here, the network is restored, and A can now connect to B anew.
> # "_127.0.0.1:47500_" is last in _List<InetSocketAddress>_ addrs by _IgniteUtils#inetAddressesComparator(boolean sameHost)_. But the connect attempts in _checkConnection(...)_ are parallel. "_127.0.0.1:47500_" answers first.
> # C sees it can connect to "_127.0.0.1:47500_" and chooses it as the alive address of B. Other pings to rest of B's addresses are ignored.
> # But "_127.0.0.1:47500_" is one of C's addresses. C realizes it pinged itself and decides that B is not reachable:
> {code:java}
>          // If local node was able to connect to previous, confirm that it's alive.
>          ok = liveAddr != null && (!liveAddr.getAddress().isLoopbackAddress() || !locNode.socketAddresses().contains(liveAddr));
> {code}
> # C accepts connection from A and answers with _TcpDiscoveryHandshakeResponse#previousNodeAlive() == false_
> # But B is ok now. But A connects to C and B is kicked from the ring.
> The problem is that C ping itself by B's address "_127.0.0.1:47500_"



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