net: Move NetClientState.info_str to dynamic allocations

The info_str field of the NetClientState structure is static and has a size
of 256 bytes. This amount is often unclaimed, and the field itself is used
exclusively for HMP "info network".

The patch translates info_str to dynamic memory allocation.

This action is also allows us to painlessly discard usage of this field
for backend devices.

Signed-off-by: Alexey Kirillov <lekiravi@yandex-team.ru>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/xen_nic.c

@@ -296,9 +296,8 @@ static int net_init(struct XenLegacyDevice *xendev)
     netdev->nic = qemu_new_nic(&net_xen_info, &netdev->conf,
                                "xen", NULL, netdev);
 
-    snprintf(qemu_get_queue(netdev->nic)->info_str,
-             sizeof(qemu_get_queue(netdev->nic)->info_str),
-             "nic: xenbus vif macaddr=%s", netdev->mac);
+    qemu_get_queue(netdev->nic)->info_str = g_strdup_printf(
+        "nic: xenbus vif macaddr=%s", netdev->mac);
 
     /* fill info */
     xenstore_write_be_int(&netdev->xendev, "feature-rx-copy", 1);

include/net/net.h

@@ -94,7 +94,7 @@ struct NetClientState {
     NetQueue *incoming_queue;
     char *model;
     char *name;
-    char info_str[256];
+    char *info_str;
     NetdevInfo *stored_config;
     unsigned receive_disabled : 1;
     NetClientDestructor *destructor;

net/l2tpv3.c

@@ -730,8 +730,7 @@ int net_init_l2tpv3(const Netdev *netdev,
     QAPI_CLONE_MEMBERS(NetdevL2TPv3Options,
                        &nc->stored_config->u.l2tpv3, l2tpv3);
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "l2tpv3: connected");
+    s->nc.info_str = g_strdup_printf("l2tpv3: connected");
     return 0;
 outerr:
     qemu_del_net_client(nc);

net/net.c

@@ -129,11 +129,12 @@ char *qemu_mac_strdup_printf(const uint8_t *macaddr)
 
 void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6])
 {
-    snprintf(nc->info_str, sizeof(nc->info_str),
-             "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
-             nc->model,
-             macaddr[0], macaddr[1], macaddr[2],
-             macaddr[3], macaddr[4], macaddr[5]);
+    g_free(nc->info_str);
+    nc->info_str = g_strdup_printf(
+        "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
+        nc->model,
+        macaddr[0], macaddr[1], macaddr[2],
+        macaddr[3], macaddr[4], macaddr[5]);
 }
 
 static int mac_table[256] = {0};
@@ -352,6 +353,7 @@ static void qemu_free_net_client(NetClientState *nc)
     }
     g_free(nc->name);
     g_free(nc->model);
+    g_free(nc->info_str);
     qapi_free_NetdevInfo(nc->stored_config);
     if (nc->destructor) {
         nc->destructor(nc);
@@ -1226,7 +1228,7 @@ void print_net_client(Monitor *mon, NetClientState *nc)
     monitor_printf(mon, "%s: index=%d,type=%s,%s\n", nc->name,
                    nc->queue_index,
                    NetClientDriver_str(nc->info->type),
-                   nc->info_str);
+                   nc->info_str ? nc->info_str : "");
     if (!QTAILQ_EMPTY(&nc->filters)) {
         monitor_printf(mon, "filters:\n");
     }

net/slirp.c

@@ -664,9 +664,8 @@ static int net_slirp_init(NetClientState *peer, const char *model,
         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");
+    nc->info_str = g_strdup_printf("net=%s,restrict=%s", inet_ntoa(net),
+                                   restricted ? "on" : "off");
 
     s = DO_UPCAST(SlirpState, nc, nc);
 

net/socket.c

@@ -180,7 +180,8 @@ static void net_socket_send(void *opaque)
         s->fd = -1;
         net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
         s->nc.link_down = true;
-        memset(s->nc.info_str, 0, sizeof(s->nc.info_str));
+        g_free(s->nc.info_str);
+        s->nc.info_str = g_new0(char, 1);
 
         return;
     }
@@ -400,16 +401,16 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
         stored->mcast = g_strdup(mcast);
 
         s->dgram_dst = saddr;
-        snprintf(nc->info_str, sizeof(nc->info_str),
-                 "socket: fd=%d (cloned mcast=%s:%d)",
-                 fd, inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
+        nc->info_str = g_strdup_printf("socket: fd=%d (cloned mcast=%s:%d)",
+                                       fd, inet_ntoa(saddr.sin_addr),
+                                       ntohs(saddr.sin_port));
     } else {
         if (sa_type == SOCKET_ADDRESS_TYPE_UNIX) {
             s->dgram_dst.sin_family = AF_UNIX;
         }
 
-        snprintf(nc->info_str, sizeof(nc->info_str),
-                 "socket: fd=%d %s", fd, SocketAddressType_str(sa_type));
+        nc->info_str = g_strdup_printf("socket: fd=%d %s",
+                                       fd, SocketAddressType_str(sa_type));
     }
 
     return s;
@@ -444,7 +445,7 @@ static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
 
     nc = qemu_new_net_client(&net_socket_info, peer, model, name);
 
-    snprintf(nc->info_str, sizeof(nc->info_str), "socket: fd=%d", fd);
+    nc->info_str = g_strdup_printf("socket: fd=%d", fd);
 
     s = DO_UPCAST(NetSocketState, nc, nc);
 
@@ -528,9 +529,10 @@ static void net_socket_accept(void *opaque)
     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));
+    g_free(s->nc.info_str);
+    s->nc.info_str = g_strdup_printf("socket: connection from %s:%d",
+                                     inet_ntoa(saddr.sin_addr),
+                                     ntohs(saddr.sin_port));
 }
 
 static int net_socket_listen_init(NetClientState *peer,
@@ -645,9 +647,10 @@ static int net_socket_connect_init(NetClientState *peer,
     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));
+    g_free(s->nc.info_str);
+    s->nc.info_str = g_strdup_printf("socket: connect to %s:%d",
+                                     inet_ntoa(saddr.sin_addr),
+                                     ntohs(saddr.sin_port));
     return 0;
 }
 
@@ -704,9 +707,10 @@ static int net_socket_mcast_init(NetClientState *peer,
         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));
+    g_free(s->nc.info_str);
+    s->nc.info_str = g_strdup_printf("socket: mcast=%s:%d",
+                                     inet_ntoa(saddr.sin_addr),
+                                     ntohs(saddr.sin_port));
     return 0;
 
 }
@@ -769,9 +773,10 @@ static int net_socket_udp_init(NetClientState *peer,
     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));
+    g_free(s->nc.info_str);
+    s->nc.info_str = g_strdup_printf("socket: udp=%s:%d",
+                                     inet_ntoa(raddr.sin_addr),
+                                     ntohs(raddr.sin_port));
     return 0;
 }
 

net/tap-win32.c

@@ -787,8 +787,7 @@ static int tap_win32_init(NetClientState *peer, const char *model,
     stored->has_ifname = true;
     stored->ifname = g_strdup(ifname);
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "tap: ifname=%s", ifname);
+    s->nc.info_str = g_strdup_printf("tap: ifname=%s", ifname);
 
     s->handle = handle;
 

net/tap.c

@@ -625,8 +625,7 @@ int net_init_bridge(const Netdev *netdev, const char *name,
         stored->helper = g_strdup(helper);
     }
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
-             br);
+    s->nc.info_str = g_strdup_printf("helper=%s,br=%s", helper, br);
 
     return 0;
 }
@@ -714,7 +713,7 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
             g_free(tmp_s);
         }
 
-        snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
+        s->nc.info_str = g_strdup_printf("fd=%d", fd);
     } else if (tap->has_helper) {
         if (!stored->has_helper) {
             stored->has_helper = true;
@@ -727,8 +726,7 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
                                        g_strdup(DEFAULT_BRIDGE_INTERFACE);
         }
 
-        snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
-                 tap->helper);
+        s->nc.info_str = g_strdup_printf("helper=%s", tap->helper);
     } else {
         if (ifname && !stored->has_ifname) {
             stored->has_ifname = true;
@@ -745,9 +743,8 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
             stored->downscript = g_strdup(downscript);
         }
 
-        snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-                 "ifname=%s,script=%s,downscript=%s", ifname, script,
-                 downscript);
+        s->nc.info_str = g_strdup_printf("ifname=%s,script=%s,downscript=%s",
+                                         ifname, script, downscript);
 
         if (strcmp(downscript, "no") != 0) {
             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);

net/vde.c

@@ -100,8 +100,7 @@ static int net_vde_init(NetClientState *peer, const char *model,
 
     nc = qemu_new_net_client(&net_vde_info, peer, model, name);
 
-    snprintf(nc->info_str, sizeof(nc->info_str), "sock=%s,fd=%d",
-             sock, vde_datafd(vde));
+    nc->info_str = g_strdup_printf("sock=%s,fd=%d", sock, vde_datafd(vde));
 
     s = DO_UPCAST(VDEState, nc, nc);
 

net/vhost-user.c

@@ -327,8 +327,7 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
     user = g_new0(struct VhostUserState, 1);
     for (i = 0; i < queues; i++) {
         nc = qemu_new_net_client(&net_vhost_user_info, peer, device, name);
-        snprintf(nc->info_str, sizeof(nc->info_str), "vhost-user%d to %s",
-                 i, chr->label);
+        nc->info_str = g_strdup_printf("vhost-user%d to %s", i, chr->label);
         nc->queue_index = i;
         if (!nc0) {
             nc0 = nc;

net/vhost-vdpa.c

@@ -200,7 +200,7 @@ static int net_vhost_vdpa_init(NetClientState *peer, const char *device,
     stored->has_queues = true;
     stored->queues = 1; /* TODO: change when support multiqueue */
 
-    snprintf(nc->info_str, sizeof(nc->info_str), TYPE_VHOST_VDPA);
+    nc->info_str = g_strdup_printf(TYPE_VHOST_VDPA);
     nc->queue_index = 0;
     s = DO_UPCAST(VhostVDPAState, nc, nc);
     vdpa_device_fd = qemu_open_old(vhostdev, O_RDWR);