[Qemu-devel] [PATCH] io: fix handling of EOF / error conditions in websock GSource

[Qemu-devel] [PATCH] io: fix handling of EOF / error conditions in websock GSource

[Daniel P. Berrangé]

We were never reporting the G_IO_HUP event when an end of file was hit
on the websocket channel.

We also ddn't report G_IO_ERR when we hit a fatal error processing the
websocket protocol.

The latter in particular meant that the chardev code would not notice
when an eof/error was encountered on the websocket channel, unless the
guest OS happened to trigger a write operation.

This meant that once the first client had quit, the chardev would never
listen to accept a new client.

Fixes launchpad bug 1816819
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 io/channel-websock.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/io/channel-websock.c b/io/channel-websock.c
index dc43dc6bb9..fc4c3dcaa5 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -1225,12 +1225,18 @@ qio_channel_websock_source_check(GSource *source)
     QIOChannelWebsockSource *wsource = (QIOChannelWebsockSource *)source;
     GIOCondition cond = 0;
 
-    if (wsource->wioc->rawinput.offset || wsource->wioc->io_eof) {
+    if (wsource->wioc->rawinput.offset) {
         cond |= G_IO_IN;
     }
     if (wsource->wioc->encoutput.offset < QIO_CHANNEL_WEBSOCK_MAX_BUFFER) {
         cond |= G_IO_OUT;
     }
+    if (wsource->wioc->io_eof) {
+        cond |= G_IO_IN | G_IO_HUP;
+    }
+    if (wsource->wioc->io_err) {
+        cond |= G_IO_IN | G_IO_ERR;
+    }
 
     return cond & wsource->condition;
 }
-- 
2.20.1

Re: [Qemu-devel] [PATCH] io: fix handling of EOF / error conditions in websock GSource

[Philippe Mathieu-Daudé]

Hi Daniel,

On 2/20/19 7:25 PM, Daniel P. Berrangé wrote:
> We were never reporting the G_IO_HUP event when an end of file was hit
> on the websocket channel.
> 
> We also ddn't report G_IO_ERR when we hit a fatal error processing the

"didn't report"

> websocket protocol.
> 
> The latter in particular meant that the chardev code would not notice
> when an eof/error was encountered on the websocket channel, unless the
> guest OS happened to trigger a write operation.
> 
> This meant that once the first client had quit, the chardev would never
> listen to accept a new client.
> 
> Fixes launchpad bug 1816819
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  io/channel-websock.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/io/channel-websock.c b/io/channel-websock.c
> index dc43dc6bb9..fc4c3dcaa5 100644
> --- a/io/channel-websock.c
> +++ b/io/channel-websock.c
> @@ -1225,12 +1225,18 @@ qio_channel_websock_source_check(GSource *source)
>      QIOChannelWebsockSource *wsource = (QIOChannelWebsockSource *)source;
>      GIOCondition cond = 0;
>  
> -    if (wsource->wioc->rawinput.offset || wsource->wioc->io_eof) {
> +    if (wsource->wioc->rawinput.offset) {
>          cond |= G_IO_IN;
>      }
>      if (wsource->wioc->encoutput.offset < QIO_CHANNEL_WEBSOCK_MAX_BUFFER) {
>          cond |= G_IO_OUT;
>      }
> +    if (wsource->wioc->io_eof) {
> +        cond |= G_IO_IN | G_IO_HUP;

Shouldn't this be:

           cond |= G_IO_HUP;

> +    }
> +    if (wsource->wioc->io_err) {
> +        cond |= G_IO_IN | G_IO_ERR;

Ditto:

           cond |= G_IO_ERR;

> +    }
>  
>      return cond & wsource->condition;
>  }
> 

Re: [Qemu-devel] [PATCH] io: fix handling of EOF / error conditions in websock GSource

[Daniel P. Berrangé]

On Wed, Feb 20, 2019 at 08:52:34PM +0100, Philippe Mathieu-Daudé wrote:
> Hi Daniel,
> 
> On 2/20/19 7:25 PM, Daniel P. Berrangé wrote:
> > We were never reporting the G_IO_HUP event when an end of file was hit
> > on the websocket channel.
> > 
> > We also ddn't report G_IO_ERR when we hit a fatal error processing the
> 
> "didn't report"
> 
> > websocket protocol.
> > 
> > The latter in particular meant that the chardev code would not notice
> > when an eof/error was encountered on the websocket channel, unless the
> > guest OS happened to trigger a write operation.
> > 
> > This meant that once the first client had quit, the chardev would never
> > listen to accept a new client.
> > 
> > Fixes launchpad bug 1816819
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> >  io/channel-websock.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/io/channel-websock.c b/io/channel-websock.c
> > index dc43dc6bb9..fc4c3dcaa5 100644
> > --- a/io/channel-websock.c
> > +++ b/io/channel-websock.c
> > @@ -1225,12 +1225,18 @@ qio_channel_websock_source_check(GSource *source)
> >      QIOChannelWebsockSource *wsource = (QIOChannelWebsockSource *)source;
> >      GIOCondition cond = 0;
> >  
> > -    if (wsource->wioc->rawinput.offset || wsource->wioc->io_eof) {
> > +    if (wsource->wioc->rawinput.offset) {
> >          cond |= G_IO_IN;
> >      }
> >      if (wsource->wioc->encoutput.offset < QIO_CHANNEL_WEBSOCK_MAX_BUFFER) {
> >          cond |= G_IO_OUT;
> >      }
> > +    if (wsource->wioc->io_eof) {
> > +        cond |= G_IO_IN | G_IO_HUP;
> 
> Shouldn't this be:
> 
>            cond |= G_IO_HUP;

With regular poll() on FD I believe you typically get POLLIN | POLLHUP as
a pair.

> 
> > +    }
> > +    if (wsource->wioc->io_err) {
> > +        cond |= G_IO_IN | G_IO_ERR;
> 
> Ditto:
> 
>            cond |= G_IO_ERR;

And I just followed the same practice here.

> > +    }
> >  
> >      return cond & wsource->condition;

Regards,
Daniel
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