[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames |
Date: |
Mon, 11 Sep 2017 18:10:15 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
On Mon, Sep 11, 2017 at 10:03:35AM -0700, Brandon Carpenter wrote:
> On Mon, Sep 11, 2017 at 1:50 AM, Daniel P. Berrange <address@hidden>
> wrote:
> > I'm concerned that there is no rate limiting here though, so if a large
> > number of PINGs are sent, and writing of the reply blocks for some
> > reason, encoutput will grow without bounds.
>
> That is a good point. How about something like this to fix it?
>
> diff --git a/include/io/channel-websock.h b/include/io/channel-websock.h
> index 7c896557c5..c5a8c3e96c 100644
> --- a/include/io/channel-websock.h
> +++ b/include/io/channel-websock.h
> @@ -66,6 +66,7 @@ struct QIOChannelWebsock {
> Error *io_err;
> gboolean io_eof;
> uint8_t opcode;
> + uint8_t prev_opcode;
> };
>
> /**
> diff --git a/io/channel-websock.c b/io/channel-websock.c
> index 175f17ce6b..a9315c01fb 100644
> --- a/io/channel-websock.c
> +++ b/io/channel-websock.c
> @@ -549,6 +549,7 @@ static int
> qio_channel_websock_decode_header(QIOChannelWebsock *ioc,
> payload_len = header->b1 & QIO_CHANNEL_WEBSOCK_HEADER_FIELD_PAYLOAD_LEN;
>
> /* Save or restore opcode. */
> + ioc->prev_opcode = ioc->opcode;
> if (opcode) {
> ioc->opcode = opcode;
> } else {
> @@ -658,9 +659,14 @@ static int
> qio_channel_websock_decode_payload(QIOChannelWebsock *ioc,
> buffer_append(&ioc->rawinput, ioc->encinput.buffer,
> payload_len);
> }
> } else if (ioc->opcode == QIO_CHANNEL_WEBSOCK_OPCODE_PING) {
> - /* ping frames produce an immediate pong reply */
> - qio_channel_websock_encode_buffer(ioc,
> - QIO_CHANNEL_WEBSOCK_OPCODE_PONG, &ioc->encinput);
> + /* Ping frames produce an immediate pong reply, unless one
> + * is already queued, in which case they are coalesced
> + * to avoid unbounded buffer growth.
> + */
> + if (!ioc->encoutput.offset || ioc->prev_opcode !=
> QIO_CHANNEL_WEBSOCK_OPCODE_PING) {
> + qio_channel_websock_encode_buffer(ioc,
> + QIO_CHANNEL_WEBSOCK_OPCODE_PONG, &ioc->encinput);
> + }
It feels like this is still dangerous - the client simply has to
interleave each "ping" with a 1 byte binary frame to get around
this limit. We need to make sure we have an absolute cap on the
output buffer size.
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
- [Qemu-devel] [PATCH v2 3/6] io: Add support for fragmented websocket binary frames, (continued)
- Message not available
- Message not available
- Message not available
- Message not available
- Message not available
Message not available
- [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Brandon Carpenter, 2017/09/08
- Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Daniel P. Berrange, 2017/09/11
- Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Brandon Carpenter, 2017/09/11
- Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames,
Daniel P. Berrange <=
- Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Brandon Carpenter, 2017/09/11
- Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Daniel P. Berrange, 2017/09/12
Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Daniel P. Berrange, 2017/09/11
Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Brandon Carpenter, 2017/09/11
Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Daniel P. Berrange, 2017/09/12
Re: [Qemu-devel] [PATCH v2 6/6] io: Reply to ping frames, Brandon Carpenter, 2017/09/12
Re: [Qemu-devel] [PATCH v2 0/6] Update websocket code to more fully support the RFC, Eric Blake, 2017/09/08