[PATCH v2 1/4] qapi: net: Add query-netdevs command

[Alexey Kirillov <lekiravi@yandex-team.ru>]

Add a qmp command that provides information about currently attached
network devices and their configuration.

Signed-off-by: Alexey Kirillov <lekiravi@yandex-team.ru>
---
 include/net/net.h |   1 +
 net/hub.c         |   8 +++
 net/l2tpv3.c      |  19 +++++++
 net/net.c         |  91 +++++++++++++++++++++++++++++++++
 net/netmap.c      |  13 +++++
 net/slirp.c       | 126 ++++++++++++++++++++++++++++++++++++++++++++++
 net/socket.c      |  71 ++++++++++++++++++++++++++
 net/tap-win32.c   |   9 ++++
 net/tap.c         | 103 +++++++++++++++++++++++++++++++++++--
 net/vde.c         |  26 ++++++++++
 net/vhost-user.c  |  18 +++++--
 qapi/net.json     |  89 ++++++++++++++++++++++++++++++++
 12 files changed, 566 insertions(+), 8 deletions(-)

diff --git a/include/net/net.h b/include/net/net.h
index e175ba9677..2c8956c0b3 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -92,6 +92,7 @@ struct NetClientState {
     char *model;
     char *name;
     char info_str[256];
+    NetdevInfo *stored_config;
     unsigned receive_disabled : 1;
     NetClientDestructor *destructor;
     unsigned int queue_index;
diff --git a/net/hub.c b/net/hub.c
index 5795a678ed..37995b5517 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -148,6 +148,7 @@ static NetHubPort *net_hub_port_new(NetHub *hub, const char *name,
     NetHubPort *port;
     int id = hub->num_ports++;
     char default_name[128];
+    NetdevHubPortOptions *stored;
 
     if (!name) {
         snprintf(default_name, sizeof(default_name),
@@ -160,6 +161,13 @@ static NetHubPort *net_hub_port_new(NetHub *hub, const char *name,
     port->id = id;
     port->hub = hub;
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_HUBPORT;
+    stored = &nc->stored_config->u.hubport;
+
+    stored->hubid = hub->id;
+
     QLIST_INSERT_HEAD(&hub->ports, port, next);
 
     return port;
diff --git a/net/l2tpv3.c b/net/l2tpv3.c
index 55fea17c0f..f4e45e7b28 100644
--- a/net/l2tpv3.c
+++ b/net/l2tpv3.c
@@ -535,6 +535,7 @@ int net_init_l2tpv3(const Netdev *netdev,
     struct addrinfo hints;
     struct addrinfo *result = NULL;
     char *srcport, *dstport;
+    NetdevL2TPv3Options *stored;
 
     nc = qemu_new_net_client(&net_l2tpv3_info, peer, "l2tpv3", name);
 
@@ -726,6 +727,24 @@ int net_init_l2tpv3(const Netdev *netdev,
 
     l2tpv3_read_poll(s, true);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_L2TPV3;
+    stored = &nc->stored_config->u.l2tpv3;
+
+    memcpy(stored, l2tpv3, sizeof(NetdevL2TPv3Options));
+
+    stored->src = g_strdup(l2tpv3->src);
+    stored->dst = g_strdup(l2tpv3->dst);
+
+    if (l2tpv3->has_srcport) {
+        stored->srcport = g_strdup(l2tpv3->srcport);
+    }
+
+    if (l2tpv3->has_dstport) {
+        stored->dstport = g_strdup(l2tpv3->dstport);
+    }
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "l2tpv3: connected");
     return 0;
diff --git a/net/net.c b/net/net.c
index 9e93c3f8a1..01e0548295 100644
--- a/net/net.c
+++ b/net/net.c
@@ -54,6 +54,7 @@
 #include "sysemu/sysemu.h"
 #include "net/filter.h"
 #include "qapi/string-output-visitor.h"
+#include "qapi/clone-visitor.h"
 
 /* Net bridge is currently not supported for W32. */
 #if !defined(_WIN32)
@@ -128,6 +129,12 @@ char *qemu_mac_strdup_printf(const uint8_t *macaddr)
 
 void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6])
 {
+    g_assert(nc->stored_config);
+
+    g_free(nc->stored_config->u.nic.macaddr);
+    nc->stored_config->u.nic.macaddr = g_strdup_printf(MAC_FMT,
+                                                       MAC_ARG(macaddr));
+
     snprintf(nc->info_str, sizeof(nc->info_str),
              "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
              nc->model,
@@ -283,6 +290,7 @@ NICState *qemu_new_nic(NetClientInfo *info,
     NetClientState **peers = conf->peers.ncs;
     NICState *nic;
     int i, queues = MAX(1, conf->peers.queues);
+    NetLegacyNicOptions *stored;
 
     assert(info->type == NET_CLIENT_DRIVER_NIC);
     assert(info->size >= sizeof(NICState));
@@ -298,6 +306,27 @@ NICState *qemu_new_nic(NetClientInfo *info,
         nic->ncs[i].queue_index = i;
     }
 
+    /* Store startup parameters */
+    nic->ncs[0].stored_config = g_new0(NetdevInfo, 1);
+    nic->ncs[0].stored_config->type = NET_CLIENT_DRIVER_NIC;
+    stored = &nic->ncs[0].stored_config->u.nic;
+
+    /* Read-only in runtime */
+    nic->ncs[0].stored_config->has_perm_mac = true;
+    nic->ncs[0].stored_config->perm_mac = g_strdup_printf(MAC_FMT,
+        MAC_ARG(conf->macaddr.a));
+
+    if (peers[0]) {
+        stored->has_netdev = true;
+        stored->netdev = g_strdup(peers[0]->name);
+    }
+
+    stored->has_macaddr = true;
+    stored->macaddr = g_strdup_printf(MAC_FMT, MAC_ARG(conf->macaddr.a));
+
+    stored->has_model = true;
+    stored->model = g_strdup(model);
+
     return nic;
 }
 
@@ -344,6 +373,7 @@ static void qemu_free_net_client(NetClientState *nc)
     }
     g_free(nc->name);
     g_free(nc->model);
+    qapi_free_NetdevInfo(nc->stored_config);
     if (nc->destructor) {
         nc->destructor(nc);
     }
@@ -1320,6 +1350,67 @@ RxFilterInfoList *qmp_query_rx_filter(bool has_name, const char *name,
     return filter_list;
 }
 
+NetdevInfoList *qmp_query_netdevs(Error **errp)
+{
+    NetdevInfoList *list = NULL;
+    NetClientState *nc;
+
+    QTAILQ_FOREACH(nc, &net_clients, next) {
+        /* Only look at netdevs, not for each queue */
+        if (nc->stored_config) {
+            NetdevInfoList *node = g_new0(NetdevInfoList, 1);
+
+            node->value = QAPI_CLONE(NetdevInfo, nc->stored_config);
+            g_free(node->value->id); /* Need to dealloc default empty id */
+            node->value->id = g_strdup(nc->name);
+
+            if (nc->info->type == NET_CLIENT_DRIVER_NIC) {
+                NICState *state = qemu_get_nic(nc);
+                assert(state);
+
+                /* NIC have explicit number of queues */
+                assert(state->conf);
+                node->value->queues_count = state->conf->peers.queues;
+            } else {
+                /* Not a NIC, but can have queues */
+                NetClientState *nc_iterable;
+
+                QTAILQ_FOREACH(nc_iterable, &net_clients, next) {
+                    if (strcmp(nc_iterable->name, nc->name) == 0) {
+                        node->value->queues_count++;
+                    }
+                }
+            }
+
+            node->value->has_peer = nc->peer != NULL;
+            if (node->value->has_peer) {
+                node->value->peer = g_strdup(nc->peer->name);
+            }
+
+            node->value->has_hub =
+                net_hub_id_for_client(nc, (int *)&node->value->hub) == 0;
+
+            /*
+             * Copy the current hubport peer id to connected netdev id,
+             * because it could have been changed at runtime
+             */
+            if (nc->info->type == NET_CLIENT_DRIVER_HUBPORT) {
+                if (node->value->has_peer) {
+                    g_free(node->value->u.hubport.netdev);
+
+                    node->value->u.hubport.has_netdev = true;
+                    node->value->u.hubport.netdev = g_strdup(nc->peer->name);
+                }
+            }
+
+            node->next = list;
+            list = node;
+        }
+    }
+
+    return list;
+}
+
 void hmp_info_network(Monitor *mon, const QDict *qdict)
 {
     NetClientState *nc, *peer;
diff --git a/net/netmap.c b/net/netmap.c
index 350f097f91..71feacb92c 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -411,6 +411,7 @@ int net_init_netmap(const Netdev *netdev,
     NetClientState *nc;
     Error *err = NULL;
     NetmapState *s;
+    NetdevNetmapOptions *stored;
 
     nmd = netmap_open(netmap_opts, &err);
     if (err) {
@@ -427,6 +428,18 @@ int net_init_netmap(const Netdev *netdev,
     pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
     netmap_read_poll(s, true); /* Initially only poll for reads. */
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_NETMAP;
+    stored = &nc->stored_config->u.netmap;
+
+    stored->ifname = g_strdup(netmap_opts->ifname);
+
+    if (netmap_opts->has_devname) {
+        stored->has_devname = true;
+        stored->devname = g_strdup(netmap_opts->devname);
+    }
+
     return 0;
 }
 
diff --git a/net/slirp.c b/net/slirp.c
index c4334ee876..fb5b87ebed 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -346,6 +346,14 @@ static SaveVMHandlers savevm_slirp_state = {
     .load_state = net_slirp_state_load,
 };
 
+#define APPEND_STRINGLIST(tail, new_val) \
+    do { \
+        *(tail) = g_new0(StringList, 1); \
+        (*(tail))->value = g_new0(String, 1); \
+        (*(tail))->value->str = g_strdup((new_val)); \
+        (tail) = &((*(tail))->next); \
+    } while (0)
+
 static int net_slirp_init(NetClientState *peer, const char *model,
                           const char *name, int restricted,
                           bool ipv4, const char *vnetwork, const char *vhost,
@@ -378,6 +386,9 @@ static int net_slirp_init(NetClientState *peer, const char *model,
     int shift;
     char *end;
     struct slirp_config_str *config;
+    NetdevUserOptions *stored;
+    StringList **stored_hostfwd;
+    StringList **stored_guestfwd;
 
     if (!ipv4 && (vnetwork || vhost || vnameserver)) {
         error_setg(errp, "IPv4 disabled but netmask/host/dns provided");
@@ -553,6 +564,112 @@ static int net_slirp_init(NetClientState *peer, const char *model,
 
     nc = qemu_new_net_client(&net_slirp_info, peer, model, name);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_USER;
+    stored = &nc->stored_config->u.user;
+
+    if (vhostname) {
+        stored->has_hostname = true;
+        stored->hostname = g_strdup(vhostname);
+    }
+
+    stored->has_q_restrict = true;
+    stored->q_restrict = restricted;
+
+    stored->has_ipv4 = true;
+    stored->ipv4 = ipv4;
+
+    stored->has_ipv6 = true;
+    stored->ipv6 = ipv6;
+
+    if (ipv4) {
+        uint8_t *net_bytes = (uint8_t *)&net;
+        uint8_t *mask_bytes = (uint8_t *)&mask;
+
+        stored->has_net = true;
+        stored->net = g_strdup_printf("%d.%d.%d.%d/%d.%d.%d.%d",
+                                      net_bytes[0], net_bytes[1],
+                                      net_bytes[2], net_bytes[3],
+                                      mask_bytes[0], mask_bytes[1],
+                                      mask_bytes[2], mask_bytes[3]);
+
+        stored->has_host = true;
+        stored->host = g_strdup(inet_ntoa(host));
+    }
+
+    if (tftp_export) {
+        stored->has_tftp = true;
+        stored->tftp = g_strdup(tftp_export);
+    }
+
+    if (bootfile) {
+        stored->has_bootfile = true;
+        stored->bootfile = g_strdup(bootfile);
+    }
+
+    if (vdhcp_start) {
+        stored->has_dhcpstart = true;
+        stored->dhcpstart = g_strdup(vdhcp_start);
+    }
+
+    if (ipv4) {
+        stored->has_dns = true;
+        stored->dns = g_strdup(inet_ntoa(dns));
+    }
+
+    if (dnssearch) {
+        stored->has_dnssearch = true;
+        StringList **stored_list = &stored->dnssearch;
+
+        for (int i = 0; dnssearch[i]; i++) {
+            APPEND_STRINGLIST(stored_list, dnssearch[i]);
+        }
+    }
+
+    if (vdomainname) {
+        stored->has_domainname = true;
+        stored->domainname = g_strdup(vdomainname);
+    }
+
+    if (ipv6) {
+        char addrstr[INET6_ADDRSTRLEN];
+        const char *res;
+
+        stored->has_ipv6_prefix = true;
+        stored->ipv6_prefix = g_strdup(vprefix6);
+
+        stored->has_ipv6_prefixlen = true;
+        stored->ipv6_prefixlen = vprefix6_len;
+
+        res = inet_ntop(AF_INET6, &ip6_host,
+                        addrstr, sizeof(addrstr));
+
+        stored->has_ipv6_host = true;
+        stored->ipv6_host = g_strdup(res);
+
+        res = inet_ntop(AF_INET6, &ip6_dns,
+                        addrstr, sizeof(addrstr));
+
+        stored->has_ipv6_dns = true;
+        stored->ipv6_dns = g_strdup(res);
+    }
+
+    if (smb_export) {
+        stored->has_smb = true;
+        stored->smb = g_strdup(smb_export);
+    }
+
+    if (vsmbserver) {
+        stored->has_smbserver = true;
+        stored->smbserver = g_strdup(vsmbserver);
+    }
+
+    if (tftp_server_name) {
+        stored->has_tftp_server_name = true;
+        stored->tftp_server_name = g_strdup(tftp_server_name);
+    }
+
     snprintf(nc->info_str, sizeof(nc->info_str),
              "net=%s,restrict=%s", inet_ntoa(net),
              restricted ? "on" : "off");
@@ -582,14 +699,23 @@ static int net_slirp_init(NetClientState *peer, const char *model,
     s->poll_notifier.notify = net_slirp_poll_notify;
     main_loop_poll_add_notifier(&s->poll_notifier);
 
+    stored_hostfwd = &stored->hostfwd;
+    stored_guestfwd = &stored->guestfwd;
+
     for (config = slirp_configs; config; config = config->next) {
         if (config->flags & SLIRP_CFG_HOSTFWD) {
             if (slirp_hostfwd(s, config->str, errp) < 0) {
                 goto error;
+            } else {
+                stored->has_hostfwd = true;
+                APPEND_STRINGLIST(stored_hostfwd, config->str);
             }
         } else {
             if (slirp_guestfwd(s, config->str, errp) < 0) {
                 goto error;
+            } else {
+                stored->has_guestfwd = true;
+                APPEND_STRINGLIST(stored_guestfwd, config->str);
             }
         }
     }
diff --git a/net/socket.c b/net/socket.c
index c92354049b..2d2d5419ca 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -342,6 +342,7 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
     NetSocketState *s;
     SocketAddress *sa;
     SocketAddressType sa_type;
+    NetdevSocketOptions *stored;
 
     sa = socket_local_address(fd, errp);
     if (!sa) {
@@ -385,8 +386,19 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
     net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
     net_socket_read_poll(s, true);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_SOCKET;
+    stored = &nc->stored_config->u.socket;
+
+    stored->has_fd = true;
+    stored->fd = g_strdup_printf("%d", fd);
+
     /* mcast: save bound address as dst */
     if (is_connected && mcast != NULL) {
+        stored->has_mcast = true;
+        stored->mcast = g_strdup(mcast);
+
         s->dgram_dst = saddr;
         snprintf(nc->info_str, sizeof(nc->info_str),
                  "socket: fd=%d (cloned mcast=%s:%d)",
@@ -428,6 +440,7 @@ static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
 {
     NetClientState *nc;
     NetSocketState *s;
+    NetdevSocketOptions *stored;
 
     nc = qemu_new_net_client(&net_socket_info, peer, model, name);
 
@@ -447,6 +460,15 @@ static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
     } else {
         qemu_set_fd_handler(s->fd, NULL, net_socket_connect, s);
     }
+
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_SOCKET;
+    stored = &nc->stored_config->u.socket;
+
+    stored->has_fd = true;
+    stored->fd = g_strdup_printf("%d", fd);
+
     return s;
 }
 
@@ -483,6 +505,7 @@ static void net_socket_accept(void *opaque)
     struct sockaddr_in saddr;
     socklen_t len;
     int fd;
+    NetdevSocketOptions *stored;
 
     for(;;) {
         len = sizeof(saddr);
@@ -498,6 +521,13 @@ static void net_socket_accept(void *opaque)
     s->fd = fd;
     s->nc.link_down = false;
     net_socket_connect(s);
+
+    /* Store additional startup parameters (extend net_socket_listen_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    stored->has_fd = true;
+    stored->fd = g_strdup_printf("%d", fd);
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "socket: connection from %s:%d",
              inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
@@ -513,6 +543,7 @@ static int net_socket_listen_init(NetClientState *peer,
     NetSocketState *s;
     struct sockaddr_in saddr;
     int fd, ret;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&saddr, host_str, errp) < 0) {
         return -1;
@@ -549,6 +580,15 @@ static int net_socket_listen_init(NetClientState *peer,
     net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
 
     qemu_set_fd_handler(s->listen_fd, net_socket_accept, NULL, s);
+
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_SOCKET;
+    stored = &nc->stored_config->u.socket;
+
+    stored->has_listen = true;
+    stored->listen = g_strdup(host_str);
+
     return 0;
 }
 
@@ -561,6 +601,7 @@ static int net_socket_connect_init(NetClientState *peer,
     NetSocketState *s;
     int fd, connected, ret;
     struct sockaddr_in saddr;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&saddr, host_str, errp) < 0) {
         return -1;
@@ -598,6 +639,12 @@ static int net_socket_connect_init(NetClientState *peer,
         return -1;
     }
 
+    /* Store additional startup parameters (extend net_socket_fd_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    stored->has_connect = true;
+    stored->connect = g_strdup(host_str);
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "socket: connect to %s:%d",
              inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
@@ -615,6 +662,7 @@ static int net_socket_mcast_init(NetClientState *peer,
     int fd;
     struct sockaddr_in saddr;
     struct in_addr localaddr, *param_localaddr;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&saddr, host_str, errp) < 0) {
         return -1;
@@ -643,6 +691,19 @@ static int net_socket_mcast_init(NetClientState *peer,
 
     s->dgram_dst = saddr;
 
+    /* Store additional startup parameters (extend net_socket_fd_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    if (!stored->has_mcast) {
+        stored->has_mcast = true;
+        stored->mcast = g_strdup(host_str);
+    }
+
+    if (localaddr_str) {
+        stored->has_localaddr = true;
+        stored->localaddr = g_strdup(localaddr_str);
+    }
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "socket: mcast=%s:%d",
              inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
@@ -660,6 +721,7 @@ static int net_socket_udp_init(NetClientState *peer,
     NetSocketState *s;
     int fd, ret;
     struct sockaddr_in laddr, raddr;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&laddr, lhost, errp) < 0) {
         return -1;
@@ -698,6 +760,15 @@ static int net_socket_udp_init(NetClientState *peer,
 
     s->dgram_dst = raddr;
 
+    /* Store additional startup parameters (extend net_socket_fd_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    stored->has_localaddr = true;
+    stored->localaddr = g_strdup(lhost);
+
+    stored->has_udp = true;
+    stored->udp = g_strdup(rhost);
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "socket: udp=%s:%d",
              inet_ntoa(raddr.sin_addr), ntohs(raddr.sin_port));
diff --git a/net/tap-win32.c b/net/tap-win32.c
index 2b5dcda36e..20ba0b1dc8 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -768,6 +768,7 @@ static int tap_win32_init(NetClientState *peer, const char *model,
     NetClientState *nc;
     TAPState *s;
     tap_win32_overlapped_t *handle;
+    NetdevTapOptions *stored;
 
     if (tap_win32_open(&handle, ifname) < 0) {
         printf("tap: Could not open '%s'\n", ifname);
@@ -778,6 +779,14 @@ static int tap_win32_init(NetClientState *peer, const char *model,
 
     s = DO_UPCAST(TAPState, nc, nc);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_TAP;
+    stored = &nc->stored_config->u.tap;
+
+    stored->has_ifname = true;
+    stored->ifname = g_strdup(ifname);
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str),
              "tap: ifname=%s", ifname);
 
diff --git a/net/tap.c b/net/tap.c
index 6207f61f84..f40f378c2a 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -584,6 +584,7 @@ int net_init_bridge(const Netdev *netdev, const char *name,
     const char *helper, *br;
     TAPState *s;
     int fd, vnet_hdr;
+    NetdevBridgeOptions *stored;
 
     assert(netdev->type == NET_CLIENT_DRIVER_BRIDGE);
     bridge = &netdev->u.bridge;
@@ -600,6 +601,21 @@ int net_init_bridge(const Netdev *netdev, const char *name,
     vnet_hdr = tap_probe_vnet_hdr(fd);
     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 
+    /* Store startup parameters */
+    s->nc.stored_config = g_new0(NetdevInfo, 1);
+    s->nc.stored_config->type = NET_CLIENT_DRIVER_BRIDGE;
+    stored = &s->nc.stored_config->u.bridge;
+
+    if (br) {
+        stored->has_br = true;
+        stored->br = g_strdup(br);
+    }
+
+    if (helper) {
+        stored->has_helper = true;
+        stored->helper = g_strdup(helper);
+    }
+
     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
              br);
 
@@ -647,11 +663,13 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
                              const char *model, const char *name,
                              const char *ifname, const char *script,
                              const char *downscript, const char *vhostfdname,
-                             int vnet_hdr, int fd, Error **errp)
+                             int vnet_hdr, int fd, NetdevInfo **common_stored,
+                             Error **errp)
 {
     Error *err = NULL;
     TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
     int vhostfd;
+    NetdevTapOptions *stored;
 
     tap_set_sndbuf(s->fd, tap, &err);
     if (err) {
@@ -659,12 +677,65 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         return;
     }
 
+    /* Store startup parameters */
+    if (!*common_stored) {
+        *common_stored = g_new0(NetdevInfo, 1);
+        (*common_stored)->type = NET_CLIENT_DRIVER_TAP;
+        s->nc.stored_config = *common_stored;
+    }
+    stored = &(*common_stored)->u.tap;
+
+    if (tap->has_sndbuf && !stored->has_sndbuf) {
+        stored->has_sndbuf = true;
+        stored->sndbuf = tap->sndbuf;
+    }
+
+    if (vnet_hdr && !stored->has_vnet_hdr) {
+        stored->has_vnet_hdr = true;
+        stored->vnet_hdr = true;
+    }
+
     if (tap->has_fd || tap->has_fds) {
+        if (!stored->has_fds) {
+            stored->has_fds = true;
+            stored->fds = g_strdup_printf("%d", fd);
+        } else {
+            char *tmp_s = stored->fds;
+            stored->fds = g_strdup_printf("%s:%d", stored->fds, fd);
+            g_free(tmp_s);
+        }
+
         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
     } else if (tap->has_helper) {
+        if (!stored->has_helper) {
+            stored->has_helper = true;
+            stored->helper = g_strdup(tap->helper);
+        }
+
+        if (!stored->has_br) {
+            stored->has_br = true;
+            stored->br = tap->has_br ? g_strdup(tap->br) :
+                                    g_strdup(DEFAULT_BRIDGE_INTERFACE);
+        }
+
         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
                  tap->helper);
     } else {
+        if (ifname && !stored->has_ifname) {
+            stored->has_ifname = true;
+            stored->ifname = g_strdup(ifname);
+        }
+
+        if (script && !stored->has_script) {
+            stored->has_script = true;
+            stored->script = g_strdup(script);
+        }
+
+        if (downscript && !stored->has_downscript) {
+            stored->has_downscript = true;
+            stored->downscript = g_strdup(downscript);
+        }
+
         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
                  "ifname=%s,script=%s,downscript=%s", ifname, script,
                  downscript);
@@ -680,9 +751,20 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
         VhostNetOptions options;
 
+        stored->has_vhost = true;
+        stored->vhost = true;
+
+        if (tap->has_vhostforce && tap->vhostforce) {
+            stored->has_vhostforce = true;
+            stored->vhostforce = true;
+        }
+
         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
         options.net_backend = &s->nc;
         if (tap->has_poll_us) {
+            stored->has_poll_us = true;
+            stored->poll_us = tap->poll_us;
+
             options.busyloop_timeout = tap->poll_us;
         } else {
             options.busyloop_timeout = 0;
@@ -715,6 +797,15 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         }
         options.opaque = (void *)(uintptr_t)vhostfd;
 
+        if (!stored->has_vhostfds) {
+            stored->has_vhostfds = true;
+            stored->vhostfds = g_strdup_printf("%d", vhostfd);
+        } else {
+            char *tmp_s = stored->vhostfds;
+            stored->vhostfds = g_strdup_printf("%s:%d", stored->fds, vhostfd);
+            g_free(tmp_s);
+        }
+
         s->vhost_net = vhost_net_init(&options);
         if (!s->vhost_net) {
             if (tap->has_vhostforce && tap->vhostforce) {
@@ -766,6 +857,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
     Error *err = NULL;
     const char *vhostfdname;
     char ifname[128];
+    NetdevInfo *common_stored = NULL; /* will store configuration */
 
     assert(netdev->type == NET_CLIENT_DRIVER_TAP);
     tap = &netdev->u.tap;
@@ -801,7 +893,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
 
         net_init_tap_one(tap, peer, "tap", name, NULL,
                          script, downscript,
-                         vhostfdname, vnet_hdr, fd, &err);
+                         vhostfdname, vnet_hdr, fd, &common_stored, &err);
         if (err) {
             error_propagate(errp, err);
             return -1;
@@ -857,7 +949,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
             net_init_tap_one(tap, peer, "tap", name, ifname,
                              script, downscript,
                              tap->has_vhostfds ? vhost_fds[i] : NULL,
-                             vnet_hdr, fd, &err);
+                             vnet_hdr, fd, &common_stored, &err);
             if (err) {
                 error_propagate(errp, err);
                 ret = -1;
@@ -896,7 +988,7 @@ free_fail:
 
         net_init_tap_one(tap, peer, "bridge", name, ifname,
                          script, downscript, vhostfdname,
-                         vnet_hdr, fd, &err);
+                         vnet_hdr, fd, &common_stored, &err);
         if (err) {
             error_propagate(errp, err);
             close(fd);
@@ -935,7 +1027,8 @@ free_fail:
             net_init_tap_one(tap, peer, "tap", name, ifname,
                              i >= 1 ? "no" : script,
                              i >= 1 ? "no" : downscript,
-                             vhostfdname, vnet_hdr, fd, &err);
+                             vhostfdname, vnet_hdr, fd,
+                             &common_stored, &err);
             if (err) {
                 error_propagate(errp, err);
                 close(fd);
diff --git a/net/vde.c b/net/vde.c
index 99189cccb6..c0ab2bb65c 100644
--- a/net/vde.c
+++ b/net/vde.c
@@ -84,6 +84,7 @@ static int net_vde_init(NetClientState *peer, const char *model,
     VDECONN *vde;
     char *init_group = (char *)group;
     char *init_sock = (char *)sock;
+    NetdevVdeOptions *stored;
 
     struct vde_open_args args = {
         .port = port,
@@ -108,6 +109,31 @@ static int net_vde_init(NetClientState *peer, const char *model,
 
     qemu_set_fd_handler(vde_datafd(s->vde), vde_to_qemu, NULL, s);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_CLIENT_DRIVER_VDE;
+    stored = &nc->stored_config->u.vde;
+
+    if (sock) {
+        stored->has_sock = true;
+        stored->sock = g_strdup(sock);
+    }
+
+    if (port) {
+        stored->has_port = true;
+        stored->port = port;
+    }
+
+    if (group) {
+        stored->has_group = true;
+        stored->group = g_strdup(group);
+    }
+
+    if (mode) {
+        stored->has_mode = true;
+        stored->mode = mode;
+    }
+
     return 0;
 }
 
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 17532daaf3..aa2dc53179 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -307,14 +307,15 @@ static void net_vhost_user_event(void *opaque, QEMUChrEvent event)
 }
 
 static int net_vhost_user_init(NetClientState *peer, const char *device,
-                               const char *name, Chardev *chr,
-                               int queues)
+                               const char *name, const char *chardev,
+                               Chardev *chr, int queues)
 {
     Error *err = NULL;
     NetClientState *nc, *nc0 = NULL;
     NetVhostUserState *s = NULL;
     VhostUserState *user;
     int i;
+    NetdevVhostUserOptions *stored;
 
     assert(name);
     assert(queues > 0);
@@ -351,6 +352,16 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
 
     assert(s->vhost_net);
 
+    /* Store startup parameters */
+    nc0->stored_config = g_new0(NetdevInfo, 1);
+    nc0->stored_config->type = NET_CLIENT_DRIVER_VHOST_USER;
+    stored = &nc0->stored_config->u.vhost_user;
+
+    stored->chardev = g_strdup(chardev);
+
+    stored->has_queues = true;
+    stored->queues = queues;
+
     return 0;
 
 err:
@@ -442,5 +453,6 @@ int net_init_vhost_user(const Netdev *netdev, const char *name,
         return -1;
     }
 
-    return net_vhost_user_init(peer, "vhost_user", name, chr, queues);
+    return net_vhost_user_init(peer, "vhost_user", name,
+                               vhost_user_opts->chardev, chr, queues);
 }
diff --git a/qapi/net.json b/qapi/net.json
index 1cb9a7d782..4f329a1de0 100644
--- a/qapi/net.json
+++ b/qapi/net.json
@@ -750,3 +750,92 @@
 ##
 { 'event': 'FAILOVER_NEGOTIATED',
   'data': {'device-id': 'str'} }
+
+##
+# @NetdevInfo:
+#
+# Configuration of a network device.
+#
+# @id: Device identifier.
+#
+# @type: Specify the driver used for interpreting remaining arguments.
+#
+# @peer: Connected network device.
+#
+# @queues-count: Number of queues.
+#
+# @hub: hubid of hub, if connected to.
+#
+# @perm-mac: Original MAC address.
+#
+# Since: 5.0
+##
+{ 'union': 'NetdevInfo',
+  'base': { 'id': 'str',
+            'type': 'NetClientDriver',
+            '*peer': 'str',
+            'queues-count': 'int',
+            '*hub': 'int',
+            '*perm-mac': 'str' },
+  'discriminator': 'type',
+  'data': {
+      'nic':        'NetLegacyNicOptions',
+      'user':       'NetdevUserOptions',
+      'tap':        'NetdevTapOptions',
+      'l2tpv3':     'NetdevL2TPv3Options',
+      'socket':     'NetdevSocketOptions',
+      'vde':        'NetdevVdeOptions',
+      'bridge':     'NetdevBridgeOptions',
+      'hubport':    'NetdevHubPortOptions',
+      'netmap':     'NetdevNetmapOptions',
+      'vhost-user': 'NetdevVhostUserOptions' } }
+
+##
+# @query-netdevs:
+#
+# Get a list of @NetdevInfo for all virtual network devices.
+#
+# Returns: a list of @NetdevInfo describing each virtual network device.
+#
+# Since: 5.0
+#
+# Example:
+#
+# -> { "execute": "query-netdevs" }
+# <- { "return": [
+#          {
+#              "peer": "netdev0",
+#              "netdev": "netdev0",
+#              "perm-mac": "52:54:00:12:34:56"
+#              "model": "virtio-net-pci",
+#              "macaddr": "52:54:00:12:34:56",
+#              "queues-count": 1,
+#              "type": "nic",
+#              "id": "net0"
+#          },
+#          {
+#              "peer": "net0",
+#              "ipv6": true,
+#              "ipv4": true,
+#              "host": "10.0.2.2",
+#              "queues-count": 1,
+#              "ipv6-dns": "fec0::3",
+#              "ipv6-prefix": "fec0::",
+#              "net": "10.0.2.0/255.255.255.0",
+#              "ipv6-host": "fec0::2",
+#              "type": "user",
+#              "dns": "10.0.2.3",
+#              "hostfwd": [
+#                  {
+#                      "str": "tcp::20004-:22"
+#                  }
+#              ],
+#              "ipv6-prefixlen": 64,
+#              "id": "netdev0",
+#              "restrict": false
+#          }
+#      ]
+#    }
+#
+##
+{ 'command': 'query-netdevs', 'returns': ['NetdevInfo'] }
-- 
2.17.1