Closing Channel causes Supply of next Channel to be immediately closed.

[bbkr]

I'm working on bigger tool using forwarding and I have to reuse local listener to open multiple channels on single session to different remote hosts/ports.

Unfortunately after channel is closed SSH connection is left in some bogus state:

react {
        whenever IO::Socket::Async.listen('127.0.0.1', $local-port) -> $connection {
            whenever $session.forward($remote-host, $remote-port,
                                      '127.0.0.1', $local-port) -> $channel {
                whenever $connection.Supply(:bin) {
                    $channel.write($_);
                    LAST $channel.close;                        <=== 1
                }
                whenever $channel.Supply(:bin) {       <==== 2
                    $connection.write($_);
                    LAST $connection.close;
                }
            }
        }

When 1 is called on first channel opened then every new channel opened after that immediately leaves block 2. I can reproduce it using provided forward.p6 file.

First request:

$ curl -v -H "Host: www.bash.org" http://127.0.0.1:8888/
*   Trying 127.0.0.1:8888...
* Connected to 127.0.0.1 (127.0.0.1) port 8888 (#0)
> GET / HTTP/1.1
> Host: www.bash.org
> User-Agent: curl/7.74.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Date: Mon, 14 Oct 2024 20:28:20 GMT
< Server: Apache/2.2.15 (CentOS)
< Last-Modified: Tue, 14 Dec 2010 19:47:34 GMT
< ETag: "28148c-0-497641785a180"
< Accept-Ranges: bytes
< Content-Length: 0
< Connection: close
< Content-Type: text/html; charset=UTF-8
<
* Closing connection 0

Second request:

$ curl -v -H "Host: www.bash.org" http://127.0.0.1:8888/
*   Trying 127.0.0.1:8888...
* Connected to 127.0.0.1 (127.0.0.1) port 8888 (#0)
> GET / HTTP/1.1
> Host: www.bash.org
> User-Agent: curl/7.74.0
> Accept: */*
>
* Empty reply from server
* Connection #0 to host 127.0.0.1 left intact
curl: (52) Empty reply from server

When not closing channel next connections work fine (of course until session limit is reached).

[bbkr]

Also there is some oddity here. Commenting out LAST $connection.close causes infinite wait on $session.forward. I completly do not see the correlation, but it is 100% reproducible.

[bbkr]

$ raku -v
Welcome to Rakudo™ v2024.08.
Implementing the Raku® Programming Language v6.d.
Built on MoarVM version 2024.08.

$ apt list --installed | grep ssh
libssh-4/oldstable,oldstable-security,now 0.9.8-0+deb11u1 arm64 [installed]
libssh2-1/oldstable,now 1.9.0-2+deb11u1 arm64 [installed,automatic]
openssh-client/oldstable,oldstable-security,now 1:8.4p1-5+deb11u3 arm64 [installed]