Re: [PATCH v3] net: stream: add a new option to automatically reconnect

[Laurent Vivier <lvivier@redhat.com>]

ping

On 1/5/23 14:13, Laurent Vivier wrote:
> In stream mode, if the server shuts down there is currently
> no way to reconnect the client to a new server without removing
> the NIC device and the netdev backend (or to reboot).
> 
> This patch introduces a reconnect option that specifies a delay
> to try to reconnect with the same parameters.
> 
> Add a new test in qtest to test the reconnect option and the
> connect/disconnect events.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
> Based-on: <20230105093751.416666-1-lvivier@redhat.com>
>      
> v3:
> - add "since 8.0" in net.json
>      
> v2:
> - rebase
> 
>   net/stream.c                |  53 ++++++++++++++++++-
>   qapi/net.json               |   7 ++-
>   qemu-options.hx             |   6 +--
>   tests/qtest/netdev-socket.c | 100 ++++++++++++++++++++++++++++++++++++
>   4 files changed, 161 insertions(+), 5 deletions(-)
> 
> diff --git a/net/stream.c b/net/stream.c
> index 37ff727e0c42..9204b4c96e40 100644
> --- a/net/stream.c
> +++ b/net/stream.c
> @@ -39,6 +39,8 @@
>   #include "io/channel-socket.h"
>   #include "io/net-listener.h"
>   #include "qapi/qapi-events-net.h"
> +#include "qapi/qapi-visit-sockets.h"
> +#include "qapi/clone-visitor.h"
>   
>   typedef struct NetStreamState {
>       NetClientState nc;
> @@ -49,11 +51,15 @@ typedef struct NetStreamState {
>       guint ioc_write_tag;
>       SocketReadState rs;
>       unsigned int send_index;      /* number of bytes sent*/
> +    uint32_t reconnect;
> +    guint timer_tag;
> +    SocketAddress *addr;
>   } NetStreamState;
>   
>   static void net_stream_listen(QIONetListener *listener,
>                                 QIOChannelSocket *cioc,
>                                 void *opaque);
> +static void net_stream_arm_reconnect(NetStreamState *s);
>   
>   static gboolean net_stream_writable(QIOChannel *ioc,
>                                       GIOCondition condition,
> @@ -170,6 +176,7 @@ static gboolean net_stream_send(QIOChannel *ioc,
>           qemu_set_info_str(&s->nc, "%s", "");
>   
>           qapi_event_send_netdev_stream_disconnected(s->nc.name);
> +        net_stream_arm_reconnect(s);
>   
>           return G_SOURCE_REMOVE;
>       }
> @@ -187,6 +194,14 @@ static gboolean net_stream_send(QIOChannel *ioc,
>   static void net_stream_cleanup(NetClientState *nc)
>   {
>       NetStreamState *s = DO_UPCAST(NetStreamState, nc, nc);
> +    if (s->timer_tag) {
> +        g_source_remove(s->timer_tag);
> +        s->timer_tag = 0;
> +    }
> +    if (s->addr) {
> +        qapi_free_SocketAddress(s->addr);
> +        s->addr = NULL;
> +    }
>       if (s->ioc) {
>           if (QIO_CHANNEL_SOCKET(s->ioc)->fd != -1) {
>               if (s->ioc_read_tag) {
> @@ -346,12 +361,37 @@ static void net_stream_client_connected(QIOTask *task, gpointer opaque)
>   error:
>       object_unref(OBJECT(s->ioc));
>       s->ioc = NULL;
> +    net_stream_arm_reconnect(s);
> +}
> +
> +static gboolean net_stream_reconnect(gpointer data)
> +{
> +    NetStreamState *s = data;
> +    QIOChannelSocket *sioc;
> +
> +    s->timer_tag = 0;
> +
> +    sioc = qio_channel_socket_new();
> +    s->ioc = QIO_CHANNEL(sioc);
> +    qio_channel_socket_connect_async(sioc, s->addr,
> +                                     net_stream_client_connected, s,
> +                                     NULL, NULL);
> +    return G_SOURCE_REMOVE;
> +}
> +
> +static void net_stream_arm_reconnect(NetStreamState *s)
> +{
> +    if (s->reconnect && s->timer_tag == 0) {
> +        s->timer_tag = g_timeout_add_seconds(s->reconnect,
> +                                             net_stream_reconnect, s);
> +    }
>   }
>   
>   static int net_stream_client_init(NetClientState *peer,
>                                     const char *model,
>                                     const char *name,
>                                     SocketAddress *addr,
> +                                  uint32_t reconnect,
>                                     Error **errp)
>   {
>       NetStreamState *s;
> @@ -364,6 +404,10 @@ static int net_stream_client_init(NetClientState *peer,
>       s->ioc = QIO_CHANNEL(sioc);
>       s->nc.link_down = true;
>   
> +    s->reconnect = reconnect;
> +    if (reconnect) {
> +        s->addr = QAPI_CLONE(SocketAddress, addr);
> +    }
>       qio_channel_socket_connect_async(sioc, addr,
>                                        net_stream_client_connected, s,
>                                        NULL, NULL);
> @@ -380,7 +424,14 @@ int net_init_stream(const Netdev *netdev, const char *name,
>       sock = &netdev->u.stream;
>   
>       if (!sock->has_server || !sock->server) {
> -        return net_stream_client_init(peer, "stream", name, sock->addr, errp);
> +        return net_stream_client_init(peer, "stream", name, sock->addr,
> +                                      sock->has_reconnect ? sock->reconnect : 0,
> +                                      errp);
> +    }
> +    if (sock->has_reconnect) {
> +        error_setg(errp, "'reconnect' option is incompatible with "
> +                         "socket in server mode");
> +        return -1;
>       }
>       return net_stream_server_init(peer, "stream", name, sock->addr, errp);
>   }
> diff --git a/qapi/net.json b/qapi/net.json
> index 522ac582edeb..d6eb30008be0 100644
> --- a/qapi/net.json
> +++ b/qapi/net.json
> @@ -585,6 +585,10 @@
>   # @addr: socket address to listen on (server=true)
>   #        or connect to (server=false)
>   # @server: create server socket (default: false)
> +# @reconnect: For a client socket, if a socket is disconnected,
> +#             then attempt a reconnect after the given number of seconds.
> +#             Setting this to zero disables this function. (default: 0)
> +#             (since 8.0)
>   #
>   # Only SocketAddress types 'unix', 'inet' and 'fd' are supported.
>   #
> @@ -593,7 +597,8 @@
>   { 'struct': 'NetdevStreamOptions',
>     'data': {
>       'addr':   'SocketAddress',
> -    '*server': 'bool' } }
> +    '*server': 'bool',
> +    '*reconnect': 'uint32' } }
>   
>   ##
>   # @NetdevDgramOptions:
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 7f99d15b231f..e8d3a384e165 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -2766,9 +2766,9 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
>       "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
>       "                configure a network backend to connect to another network\n"
>       "                using an UDP tunnel\n"
> -    "-netdev stream,id=str[,server=on|off],addr.type=inet,addr.host=host,addr.port=port[,to=maxport][,numeric=on|off][,keep-alive=on|off][,mptcp=on|off][,addr.ipv4=on|off][,addr.ipv6=on|off]\n"
> -    "-netdev stream,id=str[,server=on|off],addr.type=unix,addr.path=path[,abstract=on|off][,tight=on|off]\n"
> -    "-netdev stream,id=str[,server=on|off],addr.type=fd,addr.str=file-descriptor\n"
> +    "-netdev stream,id=str[,server=on|off],addr.type=inet,addr.host=host,addr.port=port[,to=maxport][,numeric=on|off][,keep-alive=on|off][,mptcp=on|off][,addr.ipv4=on|off][,addr.ipv6=on|off][,reconnect=seconds]\n"
> +    "-netdev stream,id=str[,server=on|off],addr.type=unix,addr.path=path[,abstract=on|off][,tight=on|off][,reconnect=seconds]\n"
> +    "-netdev stream,id=str[,server=on|off],addr.type=fd,addr.str=file-descriptor[,reconnect=seconds]\n"
>       "                configure a network backend to connect to another network\n"
>       "                using a socket connection in stream mode.\n"
>       "-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=inet,local.host=addr]\n"
> diff --git a/tests/qtest/netdev-socket.c b/tests/qtest/netdev-socket.c
> index a9db9fa06e79..b6db396599ae 100644
> --- a/tests/qtest/netdev-socket.c
> +++ b/tests/qtest/netdev-socket.c
> @@ -10,6 +10,10 @@
>   #include <glib/gstdio.h>
>   #include "../unit/socket-helpers.h"
>   #include "libqtest.h"
> +#include "qapi/qmp/qstring.h"
> +#include "qemu/sockets.h"
> +#include "qapi/qobject-input-visitor.h"
> +#include "qapi/qapi-visit-sockets.h"
>   
>   #define CONNECTION_TIMEOUT    5
>   
> @@ -141,6 +145,101 @@ static void test_stream_inet_ipv4(void)
>       qtest_quit(qts0);
>   }
>   
> +static void wait_stream_connected(QTestState *qts, const char *id,
> +                                  SocketAddress **addr)
> +{
> +    QDict *resp, *data;
> +    QString *qstr;
> +    QObject *obj;
> +    Visitor *v = NULL;
> +
> +    resp = qtest_qmp_eventwait_ref(qts, "NETDEV_STREAM_CONNECTED");
> +    g_assert_nonnull(resp);
> +    data = qdict_get_qdict(resp, "data");
> +    g_assert_nonnull(data);
> +
> +    qstr = qobject_to(QString, qdict_get(data, "netdev-id"));
> +    g_assert_nonnull(data);
> +
> +    g_assert(!strcmp(qstring_get_str(qstr), id));
> +
> +    obj = qdict_get(data, "addr");
> +
> +    v = qobject_input_visitor_new(obj);
> +    visit_type_SocketAddress(v, NULL, addr, NULL);
> +    visit_free(v);
> +    qobject_unref(resp);
> +}
> +
> +static void wait_stream_disconnected(QTestState *qts, const char *id)
> +{
> +    QDict *resp, *data;
> +    QString *qstr;
> +
> +    resp = qtest_qmp_eventwait_ref(qts, "NETDEV_STREAM_DISCONNECTED");
> +    g_assert_nonnull(resp);
> +    data = qdict_get_qdict(resp, "data");
> +    g_assert_nonnull(data);
> +
> +    qstr = qobject_to(QString, qdict_get(data, "netdev-id"));
> +    g_assert_nonnull(data);
> +
> +    g_assert(!strcmp(qstring_get_str(qstr), id));
> +    qobject_unref(resp);
> +}
> +
> +static void test_stream_inet_reconnect(void)
> +{
> +    QTestState *qts0, *qts1;
> +    int port;
> +    SocketAddress *addr;
> +
> +    port = inet_get_free_port(false);
> +    qts0 = qtest_initf("-nodefaults -M none "
> +                       "-netdev stream,id=st0,server=true,addr.type=inet,"
> +                       "addr.ipv4=on,addr.ipv6=off,"
> +                       "addr.host=127.0.0.1,addr.port=%d", port);
> +
> +    EXPECT_STATE(qts0, "st0: index=0,type=stream,\r\n", 0);
> +
> +    qts1 = qtest_initf("-nodefaults -M none "
> +                       "-netdev stream,server=false,id=st0,addr.type=inet,"
> +                       "addr.ipv4=on,addr.ipv6=off,reconnect=1,"
> +                       "addr.host=127.0.0.1,addr.port=%d", port);
> +
> +    wait_stream_connected(qts0, "st0", &addr);
> +    g_assert_cmpint(addr->type, ==, SOCKET_ADDRESS_TYPE_INET);
> +    g_assert_cmpstr(addr->u.inet.host, ==, "127.0.0.1");
> +    qapi_free_SocketAddress(addr);
> +
> +    /* kill server */
> +    qtest_quit(qts0);
> +
> +    /* check client has been disconnected */
> +    wait_stream_disconnected(qts1, "st0");
> +
> +    /* restart server */
> +    qts0 = qtest_initf("-nodefaults -M none "
> +                       "-netdev stream,id=st0,server=true,addr.type=inet,"
> +                       "addr.ipv4=on,addr.ipv6=off,"
> +                       "addr.host=127.0.0.1,addr.port=%d", port);
> +
> +    /* wait connection events*/
> +    wait_stream_connected(qts0, "st0", &addr);
> +    g_assert_cmpint(addr->type, ==, SOCKET_ADDRESS_TYPE_INET);
> +    g_assert_cmpstr(addr->u.inet.host, ==, "127.0.0.1");
> +    qapi_free_SocketAddress(addr);
> +
> +    wait_stream_connected(qts1, "st0", &addr);
> +    g_assert_cmpint(addr->type, ==, SOCKET_ADDRESS_TYPE_INET);
> +    g_assert_cmpstr(addr->u.inet.host, ==, "127.0.0.1");
> +    g_assert_cmpint(atoi(addr->u.inet.port), ==, port);
> +    qapi_free_SocketAddress(addr);
> +
> +    qtest_quit(qts1);
> +    qtest_quit(qts0);
> +}
> +
>   static void test_stream_inet_ipv6(void)
>   {
>       QTestState *qts0, *qts1;
> @@ -415,6 +514,7 @@ int main(int argc, char **argv)
>           qtest_add_func("/netdev/stream/inet/ipv4", test_stream_inet_ipv4);
>           qtest_add_func("/netdev/dgram/inet", test_dgram_inet);
>           qtest_add_func("/netdev/dgram/mcast", test_dgram_mcast);
> +        qtest_add_func("/netdev/stream/inet/reconnect", test_stream_inet_reconnect);
>       }
>       if (has_ipv6) {
>           qtest_add_func("/netdev/stream/inet/ipv6", test_stream_inet_ipv6);