2.6.30 adds a new TUNSETSNDBUF ioctl() which allows a send buffer limit
for the tap device to be specified. When this limit is reached, a tap
write() will return EAGAIN and poll() will indicate the fd isn't
writable.

This allows people to tune their setups so as to avoid e.g. UDP packet
loss when the sending application in the guest out-runs the NIC in the
host.

There is no obviously sensible default setting - a suitable value
depends mostly on the capabilities of the physical NIC through which the
packets are being sent.

Also, note that when using a bridge with netfilter enabled, we currently
never get EAGAIN because netfilter causes the packet to be immediately
orphaned. Set /proc/sys/net/bridge/bridge nf-call-iptables to zero to
disable this behaviour.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

net_tap_fd_init() already returns TAPState, so this is a sensible
cleanup in its own right.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If a write() on tapfd returns EAGAIN, return zero so that the packet
gets queued (in the case of async send) and enable polling tapfd for
writing.

When tapfd becomes writable, disable write polling and flush any queued
packets.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Add a helper to enable/disable the read polling on tapfd.

We need this, because we want to start write polling on the tapfd too
and enable/disable both types of polling independently.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If tap has any packets queued at host_net_remove time, it needs to purge
them in order to prevent a sent callback being invoked for it.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If net client sends packets asynchronously, it needs to purge its queued
packets in cleanup() so as to prevent sent callbacks being invoked with
a freed client.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Make net_client_init() accept addr=, put the value into struct
NICinfo.  Use it in pci_nic_init(), and remove arguments bus and
devfn.

Don't support addr= in third argument of monitor command pci_add,
because that clashes with its first argument.  Admittedly unelegant.

Machines "malta" and "r2d" have a default NIC with a well-known PCI
address.  Deal with that the same way as the NIC model: make
pci_nic_init() take an optional default to be used when the user
doesn't specify one.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Fix the pcap dumps on Win32 and other systems where O_BINARY is required.
Signed-off-by: NFilip Navara <filip.navara@gmail.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

The code how it is today, is totally painful to read and keep.
To begin with, the code is duplicated with the option rom loading
code that linux_boot and vga are already using.

This patch introduces a "bootable" state in NICInfo structure,
that we can use to keep track of whether or not a given nic should
be bootable, avoiding the introduction of yet another global state.

With that in hands, we move the code in vl.c to hw/pc.c, and use
the already existing infra structure to load those option roms.

Error checking code suggested by Mark McLoughlin
Signed-off-by: NGlauber Costa <glommer@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Type casts removing the const attribute are bad because
they hide the fact that the argument remains const.

They also result in a compiler warning (at least with MS-C).
Signed-off-by: NStefan Weil <weil@mail.berlios.de>

Work around buffer and ioctlsocket argument type signedness problems
Suppress a prototype which is unused on mingw32
Expand a macro to avoid warnings from some GCC versions
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If a packet is queued by qemu_send_packet(), remove I/O
handler for the tap fd until we get notification that the
packet has been sent.

A not insignificant side effect of this is we can now
drain the tap send queue in one go without fear of packets
being dropped.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Add a qemu_send_packet() variant which will queue up the packet
if it cannot be sent when all client queues are full. It later
invokes the supplied callback when the packet has been sent.

If qemu_send_packet_async() returns zero, the caller is expected
to not send any more packets until the queued packet has been
sent.

Packets are queued iff a receive() handler returns zero (indicating
queue full) and the caller has provided a sent notification callback
(indicating it will stop and start its own queue).

We need the packet sending API to support queueing because:

  - a sending client should process all available packets in one go
    (e.g. virtio-net emptying its tx ring)

  - a receiving client may not be able to handle the packet
    (e.g. -EAGAIN from write() to tapfd)

  - the sending client could detect this condition in advance
    (e.g. by select() for writable on tapfd)

  - that's too much overhead (e.g. a select() call per packet)

  - therefore the sending client must handle the condition by
    dropping the packet or queueing it

  - dropping packets is poor form; we should queue.

However, we don't want queueing to be completely transparent. We
want the sending client to stop sending packets as soon as a
packet is queued. This allows the sending client to be throttled
by the receiver.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

We'll be doing more packet queueing in later commits.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Will allow qemu_send_packet() handle queue full condition.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

This allows us to handle queue full conditions rather than dropping
the packet on the floor.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Give static type checking a chance to catch errors.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

VLANClientState's fd_read() handler doesn't read from file
descriptors, it adds a buffer to the client's receive queue.

Re-name the handlers to make things a little less confusing.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

This, apparently, is the style we prefer - all VLANClientState
should be an argument to qemu_new_vlan_client().
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Reduce the number of packets dropped under heavy network
traffic by only reading a packet from the tapfd when a
client can actually handle it.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

If a vlan client has no fd_can_read(), that means it can
always receive packets. The current code assumes it can *never*
receive packets.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

KVM uses a 64k buffer for reading from tapfd (for GSO support)
and allocates the buffer with TAPState rather than on the stack.

Not allocating it on the stack probably makes sense for qemu
anyway, so merge it in advance of GSO support.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Move portability clutter out into its own function.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

This patch reorders the initialization of slirp itself as well as its
associated features smb and redirection. So far the first reference to
slirp triggered the initialization, independent of the actual -net user
option which may carry additional parameters. Now we save any request to
add a smb export or some redirections until the actual initialization of
the stack. This also allows to move a few parameters that were passed
via global variable into the argument list of net_slirp_init.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

As host network devices can also be instantiated via the monitor, errors
should then be reported to the related monitor instead of stderr. This
requires larger refactoring, so this patch starts small with introducing
a helper to catch both cases and convert net_client_init as well as
net_slirp_redir.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

A small bit of confusion between buffers is causing errors like:

  qemu: invalid parameter '10' in 'script=/etc/qemu-ifup,fd=10'

instead of:

  qemu: invalid parameter 'script' in 'script=/etc/qemu-ifup,fd=10'
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

OK, last try: 8e4416af broke -net socket, ffad4116 tried to fix it
but broke error reporting of invalid parameters. So this patch widely
reverts ffad4116 again and intead fixes those callers of check_params
that originally suffered from overwritten buffers by using separate
ones.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

This reverts commit 8cf07dcb.

This is a sorry saga.

This commit:

  8e4416af net: Add parameter checks for VLAN clients

broken '-net socket' and this commit:

  ffad4116 net: Fix -net socket parameter checks

fixed the problem but introduced another problem which
this commit:

  8cf07dcb Fix output of uninitialized strings

fixed that final problem, but causing us to lose some
error reporting information in the process.

Meanwhile Jan posted a patch to mostly re-do ffad4116
in a way that fixes the original issue, but without
losing the error reporting information. So, let's revert
8cf07dcb and apply Jan's patch.
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Slirp uses fork_exec for spawning service processes, and QEMU uses this
for running smbd. As SIGCHLD is not handled, these processes become
zombies on termination. Fix this by installing a proper signal handler,
but also make sure we disable the signal while waiting on forked network
setup/shutdown scripts.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Fix a race in qemu_send_packet when delivering deferred packets and
add proper deferring also to qemu_sendv_packet.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMark McLoughlin <markmc@redhat.com>

In case you're wondering what connections exactly you have open
or maybe redir'ed in the past, you can't really find out from qemu
right now.

This patch enables you to see all current connections the host
only networking holds open, so you can kill them using the previous
patch.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Using the new host_net_redir command you can easily create redirections
on the fly while your VM is running.

While that's great, it's missing the removal of redirections, in case you
want to have a port closed again at a later point in time.

This patch adds support for removal of redirections.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Commit ffad4116 removed the "scratch buffer"
from check_params, but didn't care for the error messages which actually
included this string to tell the user which option was wrong. Now this string
is uninitialized, so this patch removes it from the message.

This means that the user is only told the whole parameter string and has to
pick the wrong option by himself as the callers of check_params can't know this
value any more. An alternative approach would be to revert that commit and do
whatever is needed to fix the original problem without changing check_params.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>

Signed-off-by: NPaul Brook <paul@codesourcery.com>

My commit ea053add broke -net socket by
overwriting an intermediate buffer in the added check_param. Fix this
by switching check_param to automatic buffer allocation and release, ie.
callers no longer have to worry about providing a scratch buffer.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

>> +    if (net_client_init(device, opts ? : "") < 0) {
>
> Is this a gcc extension?  Do we want to introduce this construct to the
> code base.

Valid remark, fix below.

Thanks,
Jan

-------->
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Fix net.c compile warning:

CC net.o
net.c: In function net_slirp_redir:
net.c:623: warning: format not a string literal and no format arguments
Signed-off-by: NRobert Reif <reif@earthlink.net>