[pve-devel] [PATCH http-server 2/3] anyevent: always avoid re-entering client_do_disconnect() in on_error callback

From: Fiona Ebner <f.ebner@proxmox.com>
To: pve-devel@lists.proxmox.com
Subject: [pve-devel] [PATCH http-server 2/3] anyevent: always avoid re-entering client_do_disconnect() in on_error callback
Date: Tue,  8 Apr 2025 16:20:13 +0200	[thread overview]
Message-ID: <20250408142014.86344-3-f.ebner@proxmox.com> (raw)
In-Reply-To: <20250408142014.86344-1-f.ebner@proxmox.com>

Commit f737984 ("fix #4816: do not disconnect twice if client sends no
data") introduced a 'disconnected' flag in the request state to avoid
duplicate calls to client_do_disconnect() for a given client. This
works, except in the case where client_do_disconnect() enters the
on_error callback itself. To fix this, set the 'disconnected' flag
before calling client_do_disconnect().

This was exposed by commit 07e56cc ("fix unexpected EOF for client
when closing TLS session") which introduced a call to stoptls() in
client_do_disconnect(). The documentation [0] mentions for stoptls():

> This method may invoke callbacks (and therefore the handle might be
> destroyed after it returns).

Indeed, the on_error callback might get invoked and lead to a
"detected empty handle" error message as reported in the community
forum [1].

[0]: https://metacpan.org/pod/AnyEvent::Handle#$handle-%3Estoptls
[1]: https://forum.proxmox.com/threads/164744/

Fixes: 07e56cc ("fix unexpected EOF for client when closing TLS session")
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
 src/PVE/APIServer/AnyEvent.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/PVE/APIServer/AnyEvent.pm b/src/PVE/APIServer/AnyEvent.pm
index 3f8642b..db14a7d 100644
--- a/src/PVE/APIServer/AnyEvent.pm
+++ b/src/PVE/APIServer/AnyEvent.pm
@@ -1915,8 +1915,8 @@ sub accept_connections {
 			# connection/handle if the timeout is reached before
 			# any data has been received, avoid misleading errors
 			if (!$reqstate->{disconnected}) {
-			    $self->client_do_disconnect($reqstate);
 			    $reqstate->{disconnected} = 1;
+			    $self->client_do_disconnect($reqstate);
 			}
 		    };
 		    if (my $err = $@) { syslog('err', "$err"); }
-- 
2.39.5



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