Very occasionally the sequence of events from poll would result
in getting a HANGUP on its own, instead of a HANGUP+READABLE
at the same time. In the former case we would send back an error
event to the client, but never send the empty packet to indicate
EOF.
Commit 2c85644b0b attempted to
fix a problem with tracking RPC messages from streams by doing
- if (msg->header.type == VIR_NET_REPLY) {
+ if (msg->header.type == VIR_NET_REPLY ||
+ (msg->header.type == VIR_NET_STREAM &&
+ msg->header.status != VIR_NET_CONTINUE)) {
client->nrequests--;
In other words any stream packet, with status NET_OK or NET_ERROR
would cause nrequests to be decremented. This is great if the
packet from from a synchronous virStreamFinish or virStreamAbort
API call, but wildly wrong if from a server initiated abort.
The latter resulted in 'nrequests' being decremented below zero.
This then causes all I/O for that client to be stopped.
Instead of trying to infer whether we need to decrement the
nrequests field, from the message type/status, introduce an
explicit 'bool tracked' field to mark whether the virNetMessagePtr
object is subject to tracking.
Also add a virNetMessageClear function to allow a message
contents to be cleared out, without adversely impacting the
'tracked' field as a naive memset() would do
* src/rpc/virnetmessage.c, src/rpc/virnetmessage.h: Add
a 'bool tracked' field and virNetMessageClear() API
* daemon/remote.c, daemon/stream.c, src/rpc/virnetclientprogram.c,
src/rpc/virnetclientstream.c, src/rpc/virnetserverclient.c,
src/rpc/virnetserverprogram.c: Switch over to use
virNetMessageClear() and pass in the 'bool tracked' value
when creating messages.
When sending outbound stream RPC messages, a callback is
used to re-enable stream data transmission. If the stream
aborts while one of these messages is outstanding, the
stream may have been free'd by the time it is invoked. This
results in a use-after-free error
* daemon/stream.c: Ref-count streams to avoid use-after-free
The I/O event callback processes incoming packets first, and then
does outgoing packets. If the incoming packet caused the stream to
close, then the attempt to process outgoing data resulted in an
error. This caused libvirt to then send an error back to the client,
but the stream had already been stopped. This confused the client
since it sees 2 error events.
* daemon/stream.c: Don't attempt read if stream is closed
Every active stream results in a reference being held on the
virNetServerClientPtr object. This meant that if a client quit
with any streams active, although all I/O was stopped the
virNetServerClientPtr object would leak. This causes libvirtd
to leak any file handles associated with open streams when a
client quit
To fix this, when we call virNetServerClientClose there is a
callback invoked which lets the daemon release the streams
and thus the extra references
* daemon/remote.c: Add a hook to close all streams
* daemon/stream.c, daemon/stream.h: Add API for releasing
all streams
* src/rpc/virnetserverclient.c, src/rpc/virnetserverclient.h:
Allow registration of a hook to trigger when closing client
The dispatch for the CLOSE RPC call was invoking the method
virNetServerClientClose(). This caused the client connection
to be immediately terminated. This meant the reply to the
final RPC message was never sent. Prior to the RPC rewrite
we merely flagged the connection for closing, and actually
closed it when the next RPC call dispatch had completed.
* daemon/remote.c: Flag connection for a delayed close
* daemon/stream.c: Update to use new API for closing
failed connection
* src/rpc/virnetserverclient.c, src/rpc/virnetserverclient.h:
Add support for a delayed connection close. Rename the
virNetServerClientMarkClose method to virNetServerClientImmediateClose
to clarify its semantics
If a client disconnects while it has a stream active, there is
a race condition which could see libvirtd crash. This is because
the client struct may be freed before the last stream event has
triggered. This is trivially solved by holding an extra reference
on the client for the stream callbak
* daemon/stream.c: Acquire reference on client when adding the
stream callback
If a message packet for a invalid stream is received it is just
free'd. This is not good because it doesn't let the client RPC
request counter decrement. If a stream is shutdown with pending
packets the message also isn't released properly because of an
incorrect header type
* daemon/stream.c: Fix message header type
* src/rpc/virnetserverprogram.c: Send dummy reply instead of
free'ing ignored stream message
The stream code was reusing a stream message object before
it was removed from the linked list of filtered messages.
This caused any later queued messages to be completely lost.
* daemon/stream.c: Delay reuse of stream message until
after it is removed from the queue
This guts the libvirtd daemon, removing all its networking and
RPC handling code. Instead it calls out to the new virServerPtr
APIs for all its RPC & networking work
As a fallout all libvirtd daemon error reporting now takes place
via the normal internal error reporting APIs. There is no need
to call separate error reporting APIs in RPC code, nor should
code use VIR_WARN/VIR_ERROR for reporting fatal problems anymore.
* daemon/qemu_dispatch_*.h, daemon/remote_dispatch_*.h: Remove
old generated dispatcher code
* daemon/qemu_dispatch.h, daemon/remote_dispatch.h: New dispatch
code
* daemon/dispatch.c, daemon/dispatch.h: Remove obsoleted code
* daemon/remote.c, daemon/remote.h: Rewrite for new dispatch
APIs
* daemon/libvirtd.c, daemon/libvirtd.h: Remove all networking
code
* daemon/stream.c, daemon/stream.h: Update for new APIs
* daemon/Makefile.am: Link to libvirt-net-rpc-server.la
virStreamNew needs to dispatch the error that virGetStream reports
on failure.
remoteCreateClientStream can fail due to virStreamNew or due to
VIR_ALLOC. Report OOM error for VIR_ALLOC failure to report errors
in all error cases.
Remove OOM error reporting from remoteCreateClientStream callers.
These VIR_XXXX0 APIs make us confused, use the non-0-suffix APIs instead.
How do these coversions works? The magic is using the gcc extension of ##.
When __VA_ARGS__ is empty, "##" will swallow the "," in "fmt," to
avoid compile error.
example: origin after CPP
high_level_api("%d", a_int) low_level_api("%d", a_int)
high_level_api("a string") low_level_api("a string")
About 400 conversions.
8 special conversions:
VIR_XXXX0("") -> VIR_XXXX("msg") (avoid empty format) 2 conversions
VIR_XXXX0(string_literal_with_%) -> VIR_XXXX(%->%%) 0 conversions
VIR_XXXX0(non_string_literal) -> VIR_XXXX("%s", non_string_literal)
(for security) 6 conversions
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
The dispatcher functions have numerous places where they
return to the caller. This leads to duplicated cleanup
code, often resulting in memory leaks. It makes it harder
to ensure that errors are dispatched before freeing objects,
which may overwrite the original error.
The standard pattern is now
remoteDispatchXXX(...) {
int rv = -1;
....
if (XXX < 0)
goto cleanup;
...
if (XXXX < 0)
goto cleanup;
...
rv = 0;
cleanup:
if (rv < 0)
remoteDispatchError(rerr);
...free all other stuff..
return rv;
}
* daemon/remote.c: Centralize all cleanup paths
* daemon/stream.c: s/remoteDispatchConnError/remoteDispatchError/
* daemon/dispatch.c, daemon/dispatch.h: Replace
remoteDispatchConnError with remoteDispatchError
removing unused virConnectPtr
The daemon loops over the linked list of streams when a client
quits, closing any that the client hadn't already closed. Except
it didn't ever move to the next element in the list!
* daemon/stream.c: Fix loop over linked list of streams
Done mechanically with:
$ git grep -l '\bDEBUG0\? *(' | xargs -L1 sed -i 's/\bDEBUG0\? *(/VIR_&/'
followed by manual deletion of qemudDebug in daemon/libvirtd.c, along
with a single 'make syntax-check' fallout in the same file, and the
actual deletion in src/util/logging.h.
* src/util/logging.h (DEBUG, DEBUG0): Delete.
* daemon/libvirtd.h (qemudDebug): Likewise.
* global: Change remaining clients over to VIR_DEBUG counterpart.
When closing open streams after a client quits, the event
callback was not removed. This mean that poll() was using
a closed FD and returning POLLNVAL in a busy-wait loop.
* daemon/stream.c: Disconnect stream callbacks
Right now, the stream stuff assumes that a stream is always
going to be used for transmit. This is not the case, and in
fact doesn't work with the tunnelled migration stuff. Add
a flag to remoteClientStream() to allow it to do RX only.
Signed-off-by: Chris Lalancette <clalance@redhat.com>
* daemon/dispatch.c: Set streamTX flag on outgoing data packets
* daemon/qemud.h: Add streamTX flag to track outgoing data
* daemon/qemud.c: Re-enable further TX when outgoing data packet
has been fully sent.
* daemon/stream.h, daemon/stream.c: Add method for enabling TX.
Support reading from streams and transmitting data out to client
Defines the extensions to the remote protocol for generic
data streams. Adds a bunch of helper code to the libvirtd
daemon for working with data streams.
* daemon/Makefile.am: Add stream.c/stream.h to build
* daemon/stream.c, qemud/stream.h: Generic helper functions for
creating new streams, associating streams with clients, finding
existing streams for a client and removing/deleting streams.
* src/remote/remote_protocol.x: Add a new 'REMOTE_STREAM' constant
for the 'enum remote_message_type' for encoding stream data
in wire messages. Add a new 'REMOTE_CONTINUE' constant to
'enum remote_message_status' to indicate further data stream
messsages are expected to follow. Document how the
remote_message_header is used to encode data streams
* src/remote/remote_protocol.h: Regenerate
* daemon/dispatch.c: Remove assumption that a error message
sent to client is always type=REMOTE_REPLY. It may now
also be type=REMOTE_STREAM. Add convenient method for
sending outgoing stream data packets. Log and ignore
non-filtered incoming stream packets. Add a method for
serializing a stream error message
* daemon/dispatch.h: Add API for serializing stream errors
and sending stream data packets
* daemon/qemud.h: Add struct qemud_client_stream for tracking
active data streams for clients. Tweak filter function
operation so that it accepts a client object too.
* daemon/qemud.c: Refactor code for free'ing message objects
which have been fully transmitted into separate method.
Release all active streams when client shuts down. Change
filter function to be responsible for queueing the message
