Re: [RFC PATCH v2 3/8] qapi: net: add stream and dgram netdevs

[Markus Armbruster]

Laurent Vivier <lvivier@redhat.com> writes:

> On 13/05/2022 13:44, Markus Armbruster wrote:
>> Laurent Vivier <lvivier@redhat.com> writes:
>> 
>>> Copied from socket netdev file and modified to use SocketAddress
>>> to be able to introduce new features like unix socket.
>>>
>>> "udp" and "mcast" are squashed into dgram netdev, multicast is detected
>>> according to the IP address type.
>>> "listen" and "connect" modes are managed by stream netdev. An optional
>>> parameter "server" defines the mode (server by default)
>>>
>>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>>> ---
>>>   hmp-commands.hx |   2 +-
>>>   net/clients.h   |   6 +
>>>   net/dgram.c     | 630 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>   net/hub.c       |   2 +
>>>   net/meson.build |   2 +
>>>   net/net.c       |  24 +-
>>>   net/stream.c    | 425 ++++++++++++++++++++++++++++++++
>>>   qapi/net.json   |  38 ++-
>>>   8 files changed, 1125 insertions(+), 4 deletions(-)
>>>   create mode 100644 net/dgram.c
>>>   create mode 100644 net/stream.c
>>>
>>> diff --git a/hmp-commands.hx b/hmp-commands.hx
>>> index 03e6a73d1f55..172dbab1dfed 100644
>>> --- a/hmp-commands.hx
>>> +++ b/hmp-commands.hx
>>> @@ -1269,7 +1269,7 @@ ERST
>>>       {
>>>           .name       = "netdev_add",
>>>           .args_type  = "netdev:O",
>>> -        .params     = 
>>> "[user|tap|socket|vde|bridge|hubport|netmap|vhost-user],id=str[,prop=value][,...]",
>>> +        .params     = 
>>> "[user|tap|socket|stream|dgram|vde|bridge|hubport|netmap|vhost-user],id=str[,prop=value][,...]",
>>>           .help       = "add host network device",
>>>           .cmd        = hmp_netdev_add,
>>>           .command_completion = netdev_add_completion,
>> 
>> Does qemu-options.hx need an update, too?
>
> Done
>
>> 
>>> diff --git a/net/clients.h b/net/clients.h
>>> index 92f9b59aedce..c1b51d79b147 100644
>>> --- a/net/clients.h
>>> +++ b/net/clients.h
>>> @@ -40,6 +40,12 @@ int net_init_hubport(const Netdev *netdev, const char 
>>> *name,
>>>   int net_init_socket(const Netdev *netdev, const char *name,
>>>                       NetClientState *peer, Error **errp);
>>>   
>>> +int net_init_stream(const Netdev *netdev, const char *name,
>>> +                    NetClientState *peer, Error **errp);
>>> +
>>> +int net_init_dgram(const Netdev *netdev, const char *name,
>>> +                   NetClientState *peer, Error **errp);
>>> +
>>>   int net_init_tap(const Netdev *netdev, const char *name,
>>>                    NetClientState *peer, Error **errp);
>>>   
>>> diff --git a/net/dgram.c b/net/dgram.c
>>> new file mode 100644
>>> index 000000000000..aa4240501ed0
>>> --- /dev/null
>>> +++ b/net/dgram.c
>>> @@ -0,0 +1,630 @@
>>> +/*
>>> + * QEMU System Emulator
>>> + *
>>> + * Copyright (c) 2003-2008 Fabrice Bellard
>>> + *
>>> + * Permission is hereby granted, free of charge, to any person obtaining a 
>>> copy
>>> + * of this software and associated documentation files (the "Software"), 
>>> to deal
>>> + * in the Software without restriction, including without limitation the 
>>> rights
>>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or 
>>> sell
>>> + * copies of the Software, and to permit persons to whom the Software is
>>> + * furnished to do so, subject to the following conditions:
>>> + *
>>> + * The above copyright notice and this permission notice shall be included 
>>> in
>>> + * all copies or substantial portions of the Software.
>>> + *
>>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
>>> OR
>>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
>>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
>>> OTHER
>>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
>>> FROM,
>>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 
>>> IN
>>> + * THE SOFTWARE.
>>> + */
>> 
>> Blank line here, please.
>> 
>> Why not GPLv2+?
>
> I've kept the original text copied from net/socket.c, but I can move this to 
> GPL2+

If the file's contents is derived from net/socket.c, copying the
legalese from there makes sense.

>>> +#include "qemu/osdep.h"
>> 
>> [...]
>> 
>>> diff --git a/net/net.c b/net/net.c
>>> index 2aab7167316c..fd6b30a10c57 100644
>>> --- a/net/net.c
>>> +++ b/net/net.c
>>> @@ -1015,6 +1015,8 @@ static int (* const 
>>> net_client_init_fun[NET_CLIENT_DRIVER__MAX])(
>>>   #endif
>>>           [NET_CLIENT_DRIVER_TAP]       = net_init_tap,
>>>           [NET_CLIENT_DRIVER_SOCKET]    = net_init_socket,
>>> +        [NET_CLIENT_DRIVER_STREAM]    = net_init_stream,
>>> +        [NET_CLIENT_DRIVER_DGRAM]     = net_init_dgram,
>>>   #ifdef CONFIG_VDE
>>>           [NET_CLIENT_DRIVER_VDE]       = net_init_vde,
>>>   #endif
>>> @@ -1097,6 +1099,8 @@ void show_netdevs(void)
>>>       int idx;
>>>       const char *available_netdevs[] = {
>>>           "socket",
>>> +        "stream",
>>> +        "dgram",
>>>           "hubport",
>>>           "tap",
>>>   #ifdef CONFIG_SLIRP
>>> @@ -1606,7 +1610,25 @@ int net_init_clients(Error **errp)
>>>    */
>>>   static bool netdev_is_modern(const char *optarg)
>>>   {
>>> -    return false;
>>> +    static QemuOptsList dummy_opts = {
>>> +        .name = "netdev",
>>> +        .implied_opt_name = "type",
>>> +        .head = QTAILQ_HEAD_INITIALIZER(dummy_opts.head),
>>> +        .desc = { { } },
>>> +    };
>>> +    const char *netdev;
>>> +    QemuOpts *opts;
>>> +    bool is_modern;
>>> +
>>> +    opts = qemu_opts_parse(&dummy_opts, optarg, true, &error_fatal);
>>> +    netdev = qemu_opt_get(opts, "type");
>>> +
>>> +    is_modern = strcmp(netdev, "stream") == 0 ||
>>> +                strcmp(netdev, "dgram") == 0;
>> 
>> Crashes when user neglects to pass "type".
>
> I think "type" is always passed because of the '.implied_opt_name = "type"'. 
> Am I wrong?

.implied_opt_name = "type" lets you shorten "type=T,..." to "T,...".  It
doesn't make key "type" mandatory.  "-netdev id=foo" is still permitted.
Even "-netdev ''" is.

>>> +
>>> +    qemu_opts_reset(&dummy_opts);
>>> +
>>> +    return is_modern;
>>>   }
>> 
>> Reminder: netdev_is_modern() governs whether to use QemuOpts + opts
>> visitor or qobject_input_visitor_new_str().
>> 
>> To decide, it uses QemuOpts with a dummy QemuOptsList.
>> 
>> Since we parse errors are fatal here, new syntax must also parse fine as
>> QemuOpts.  Undesirable, I think.
>> 
>> Cleaner, I think:
>> 
>>      args = keyval_parse(optarg, "type", NULL, NULL);
>>      if (!args) {
>>          return false;
>>      }
>>      type = qdict_get_try_str(args, "type");
>>      return !g_strcmp0(type, "dgram") || !g_strcmp0(type, "stream");
>> 
>> Not even compile-tested.
>
> ok, I try that.
>
>> Still probematic: syntax error reporting.  When keyval_parse() fails
>> here, we use QemuOpts, and therefore get QemuOpts syntax errors.  I fear
>> that could be quite confusing.
>> 
>>>   
>>>   int net_client_parse(QemuOptsList *opts_list, const char *optarg)
>>> diff --git a/net/stream.c b/net/stream.c
>>> new file mode 100644
>>> index 000000000000..fdc97ee43a56
>>> --- /dev/null
>>> +++ b/net/stream.c
>>> @@ -0,0 +1,425 @@
>>> +/*
>>> + * QEMU System Emulator
>>> + *
>>> + * Copyright (c) 2003-2008 Fabrice Bellard
>>> + *
>>> + * Permission is hereby granted, free of charge, to any person obtaining a 
>>> copy
>>> + * of this software and associated documentation files (the "Software"), 
>>> to deal
>>> + * in the Software without restriction, including without limitation the 
>>> rights
>>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or 
>>> sell
>>> + * copies of the Software, and to permit persons to whom the Software is
>>> + * furnished to do so, subject to the following conditions:
>>> + *
>>> + * The above copyright notice and this permission notice shall be included 
>>> in
>>> + * all copies or substantial portions of the Software.
>>> + *
>>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
>>> OR
>>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
>>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
>>> OTHER
>>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
>>> FROM,
>>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 
>>> IN
>>> + * THE SOFTWARE.
>>> + */
>> 
>> Blank line here, please.
>> 
>> Why not GPLv2+?
>
> As above.
>
>> 
>>> +#include "qemu/osdep.h"
>> 
>> [...]
>> 
>>> diff --git a/qapi/net.json b/qapi/net.json
>>> index b92f3f5fb444..eef288886e1b 100644
>>> --- a/qapi/net.json
>>> +++ b/qapi/net.json
>>> @@ -7,6 +7,7 @@
>>>   ##
>>>   
>>>   { 'include': 'common.json' }
>>> +{ 'include': 'sockets.json' }
>>>   
>>>   ##
>>>   # @set_link:
>>> @@ -452,6 +453,37 @@
>>>       '*vhostdev':     'str',
>>>       '*queues':       'int' } }
>>>   
>>> +##
>>> +# @NetdevStreamOptions:
>>> +#
>>> +# Configuration info for stream socket netdev
>>> +#
>>> +# @addr: socket address to listen on (server=true)
>>> +#        or connect to (server=false)
>>> +# @server: create server socket (default: true)
>>> +#
>>> +# Since: 7.1
>>> +##
>>> +{ 'struct': 'NetdevStreamOptions',
>>> +  'data': {
>>> +    'addr':   'SocketAddress',
>>> +    '*server': 'bool' } }
>>> +
>>> +##
>>> +# @NetdevDgramOptions:
>>> +#
>>> +# Configuration info for datagram socket netdev.
>>> +#
>>> +# @remote: remote address
>>> +# @local: local address
>> 
>> Defaults?
>
> We can't have a default because for multicast default is remoTe, and for 
> unicast default 
> is local.

Well, the members are optional, so there must be some default behavior,
which may or may not correspond to a single default value.  Regardless,
what happens when a member is absent ought to be documented.
>> 
>>> +#
>>> +# Since: 7.1
>>> +##
>>> +{ 'struct': 'NetdevDgramOptions',
>>> +  'data': {
>>> +    '*local':  'SocketAddress',
>>> +    '*remote': 'SocketAddress' } }
>>> +
>>>   ##
>>>   # @NetClientDriver:
>>>   #
>>> @@ -462,8 +494,8 @@
>>>   #        @vhost-vdpa since 5.1
>>>   ##
>>>   { 'enum': 'NetClientDriver',
>>> -  'data': [ 'none', 'nic', 'user', 'tap', 'l2tpv3', 'socket', 'vde',
>>> -            'bridge', 'hubport', 'netmap', 'vhost-user', 'vhost-vdpa' ] }
>>> +  'data': [ 'none', 'nic', 'user', 'tap', 'l2tpv3', 'socket', 'stream', 
>>> 'dgram',
>>> +            'vde', 'bridge', 'hubport', 'netmap', 'vhost-user', 
>>> 'vhost-vdpa' ] }
>> 
>> Long lines.
>
> ok
>
>>>   
>>>   ##
>>>   # @Netdev:
>>> @@ -487,6 +519,8 @@
>>>       'tap':      'NetdevTapOptions',
>>>       'l2tpv3':   'NetdevL2TPv3Options',
>>>       'socket':   'NetdevSocketOptions',
>>> +    'stream':   'NetdevStreamOptions',
>>> +    'dgram':    'NetdevDgramOptions',
>>>       'vde':      'NetdevVdeOptions',
>>>       'bridge':   'NetdevBridgeOptions',
>>>       'hubport':  'NetdevHubPortOptions',
>> 
>
> Thanks,
> Laurent

You're welcome!