net: dgram: add unix socket

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com> (QAPI schema)
Signed-off-by: Jason Wang <jasowang@redhat.com>

net/dgram.c

@@ -426,6 +426,7 @@ int net_init_dgram(const Netdev *netdev, const char *name,
     SocketAddress *remote, *local;
     struct sockaddr *dest_addr;
     struct sockaddr_in laddr_in, raddr_in;
+    struct sockaddr_un laddr_un, raddr_un;
     socklen_t dest_len;
 
     assert(netdev->type == NET_CLIENT_DRIVER_DGRAM);
@@ -465,7 +466,8 @@ int net_init_dgram(const Netdev *netdev, const char *name,
         }
     } else {
         if (local->type != SOCKET_ADDRESS_TYPE_FD) {
-            error_setg(errp, "type=inet requires remote parameter");
+            error_setg(errp,
+                       "type=inet or type=unix requires remote parameter");
             return -1;
         }
     }
@@ -508,6 +510,53 @@ int net_init_dgram(const Netdev *netdev, const char *name,
         dest_addr = g_malloc(dest_len);
         memcpy(dest_addr, &raddr_in, dest_len);
         break;
+    case SOCKET_ADDRESS_TYPE_UNIX:
+        ret = unlink(local->u.q_unix.path);
+        if (ret < 0 && errno != ENOENT) {
+            error_setg_errno(errp, errno, "failed to unlink socket %s",
+                             local->u.q_unix.path);
+            return -1;
+        }
+
+        laddr_un.sun_family = PF_UNIX;
+        ret = snprintf(laddr_un.sun_path, sizeof(laddr_un.sun_path), "%s",
+                       local->u.q_unix.path);
+        if (ret < 0 || ret >= sizeof(laddr_un.sun_path)) {
+            error_setg(errp, "UNIX socket path '%s' is too long",
+                       local->u.q_unix.path);
+            error_append_hint(errp, "Path must be less than %zu bytes\n",
+                              sizeof(laddr_un.sun_path));
+        }
+
+        raddr_un.sun_family = PF_UNIX;
+        ret = snprintf(raddr_un.sun_path, sizeof(raddr_un.sun_path), "%s",
+                       remote->u.q_unix.path);
+        if (ret < 0 || ret >= sizeof(raddr_un.sun_path)) {
+            error_setg(errp, "UNIX socket path '%s' is too long",
+                       remote->u.q_unix.path);
+            error_append_hint(errp, "Path must be less than %zu bytes\n",
+                              sizeof(raddr_un.sun_path));
+        }
+
+        fd = qemu_socket(PF_UNIX, SOCK_DGRAM, 0);
+        if (fd < 0) {
+            error_setg_errno(errp, errno, "can't create datagram socket");
+            return -1;
+        }
+
+        ret = bind(fd, (struct sockaddr *)&laddr_un, sizeof(laddr_un));
+        if (ret < 0) {
+            error_setg_errno(errp, errno, "can't bind unix=%s to socket",
+                             laddr_un.sun_path);
+            closesocket(fd);
+            return -1;
+        }
+        qemu_socket_set_nonblock(fd);
+
+        dest_len = sizeof(raddr_un);
+        dest_addr = g_malloc(dest_len);
+        memcpy(dest_addr, &raddr_un, dest_len);
+        break;
     case SOCKET_ADDRESS_TYPE_FD:
         fd = monitor_fd_param(monitor_cur(), local->u.fd.str, errp);
         if (fd == -1) {
@@ -546,6 +595,10 @@ int net_init_dgram(const Netdev *netdev, const char *name,
                           inet_ntoa(raddr_in.sin_addr),
                           ntohs(raddr_in.sin_port));
         break;
+    case SOCKET_ADDRESS_TYPE_UNIX:
+        qemu_set_info_str(&s->nc, "udp=%s:%s",
+                          laddr_un.sun_path, raddr_un.sun_path);
+        break;
     case SOCKET_ADDRESS_TYPE_FD: {
         SocketAddress *sa;
         SocketAddressType sa_type;

qapi/net.json

@@ -603,7 +603,7 @@
 # @remote: remote address
 # @local: local address
 #
-# Only SocketAddress types 'inet' and 'fd' are supported.
+# Only SocketAddress types 'unix', 'inet' and 'fd' are supported.
 #
 # If remote address is present and it's a multicast address, local address
 # is optional. Otherwise local address is required and remote address is

qemu-options.hx

@@ -2782,6 +2782,7 @@ DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
     "                configure a network backend to connect to a multicast maddr and port\n"
     "                use ``local.host=addr`` to specify the host address to send packets from\n"
     "-netdev dgram,id=str,local.type=inet,local.host=addr,local.port=port[,remote.type=inet,remote.host=addr,remote.port=port]\n"
+    "-netdev dgram,id=str,local.type=unix,local.path=path[,remote.type=unix,remote.path=path]\n"
     "-netdev dgram,id=str,local.type=fd,local.str=file-descriptor\n"
     "                configure a network backend to connect to another network\n"
     "                using an UDP tunnel\n"