ui: add an embedded Barrier client

This allows to receive mouse and keyboard events from
a Barrier server.

This is enabled by adding the following parameter on the
command line

    ... -object input-barrier,id=$id,name=$name ...

Where $name is the name declared in the screens section of barrier.conf

The barrier server (barriers) must be configured and must run on the
local host.

For instance:

  section: screens
      localhost:
          ...
      VM-1:
          ...
      end

  section: links
      localhost:
          right = VM-1
      VM-1:
          left = localhost
  end

Then on the QEMU command line:

    ... -object input-barrier,id=barrie0,name=VM-1 ...

When the mouse will move out of the screen of the local host on
the right, the mouse and the keyboard will be grabbed and all
related events will be send to the guest OS.

This is usefull when qemu is configured without emulated graphic card
but with a VFIO attached graphic card.

More information about Barrier can be found at:

  https://github.com/debauchee/barrier

This avoids to install the Barrier server in the guest OS,
for instance when it is not supported or during the installation.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-id: 20190906083812.29487-1-laurent@vivier.eu
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

3 files changed, 863 insertions, 0 deletions

diff --git a/ui/Makefile.objs b/ui/Makefile.objs
index ba39080edb..e6da6ff047 100644
--- a/ui/Makefile.objs
+++ b/ui/Makefile.objs
@@ -9,6 +9,7 @@ vnc-obj-y += vnc-jobs.o
 
 common-obj-y += keymaps.o console.o cursor.o qemu-pixman.o
 common-obj-y += input.o input-keymap.o input-legacy.o kbd-state.o
+common-obj-y += input-barrier.o
 common-obj-$(CONFIG_LINUX) += input-linux.o
 common-obj-$(CONFIG_SPICE) += spice-core.o spice-input.o spice-display.o
 common-obj-$(CONFIG_COCOA) += cocoa.o
diff --git a/ui/input-barrier.c b/ui/input-barrier.c
new file mode 100644
index 0000000000..a2c961f285
--- /dev/null
+++ b/ui/input-barrier.c
@@ -0,0 +1,750 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "sysemu/sysemu.h"
+#include "qemu/main-loop.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "qom/object_interfaces.h"
+#include "io/channel-socket.h"
+#include "ui/input.h"
+#include "ui/vnc_keysym.h" /* use name2keysym from VNC as we use X11 values */
+#include "qemu/cutils.h"
+#include "qapi/qmp/qerror.h"
+#include "input-barrier.h"
+
+#define TYPE_INPUT_BARRIER "input-barrier"
+#define INPUT_BARRIER(obj) \
+    OBJECT_CHECK(InputBarrier, (obj), TYPE_INPUT_BARRIER)
+#define INPUT_BARRIER_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(InputBarrierClass, (obj), TYPE_INPUT_BARRIER)
+#define INPUT_BARRIER_CLASS(klass) \
+    OBJECT_CLASS_CHECK(InputBarrierClass, (klass), TYPE_INPUT_BARRIER)
+
+typedef struct InputBarrier InputBarrier;
+typedef struct InputBarrierClass InputBarrierClass;
+
+#define MAX_HELLO_LENGTH 1024
+
+struct InputBarrier {
+    Object parent;
+
+    QIOChannelSocket *sioc;
+    guint ioc_tag;
+
+    /* display properties */
+    gchar *name;
+    int16_t x_origin, y_origin;
+    int16_t width, height;
+
+    /* keyboard/mouse server */
+
+    SocketAddress saddr;
+
+    char buffer[MAX_HELLO_LENGTH];
+};
+
+struct InputBarrierClass {
+    ObjectClass parent_class;
+};
+
+static const char *cmd_names[] = {
+    [barrierCmdCNoop]          = "CNOP",
+    [barrierCmdCClose]         = "CBYE",
+    [barrierCmdCEnter]         = "CINN",
+    [barrierCmdCLeave]         = "COUT",
+    [barrierCmdCClipboard]     = "CCLP",
+    [barrierCmdCScreenSaver]   = "CSEC",
+    [barrierCmdCResetOptions]  = "CROP",
+    [barrierCmdCInfoAck]       = "CIAK",
+    [barrierCmdCKeepAlive]     = "CALV",
+    [barrierCmdDKeyDown]       = "DKDN",
+    [barrierCmdDKeyRepeat]     = "DKRP",
+    [barrierCmdDKeyUp]         = "DKUP",
+    [barrierCmdDMouseDown]     = "DMDN",
+    [barrierCmdDMouseUp]       = "DMUP",
+    [barrierCmdDMouseMove]     = "DMMV",
+    [barrierCmdDMouseRelMove]  = "DMRM",
+    [barrierCmdDMouseWheel]    = "DMWM",
+    [barrierCmdDClipboard]     = "DCLP",
+    [barrierCmdDInfo]          = "DINF",
+    [barrierCmdDSetOptions]    = "DSOP",
+    [barrierCmdDFileTransfer]  = "DFTR",
+    [barrierCmdDDragInfo]      = "DDRG",
+    [barrierCmdQInfo]          = "QINF",
+    [barrierCmdEIncompatible]  = "EICV",
+    [barrierCmdEBusy]          = "EBSY",
+    [barrierCmdEUnknown]       = "EUNK",
+    [barrierCmdEBad]           = "EBAD",
+    [barrierCmdHello]          = "Barrier",
+    [barrierCmdHelloBack]      = "Barrier",
+};
+
+static kbd_layout_t *kbd_layout;
+
+static int input_barrier_to_qcode(uint16_t keyid, uint16_t keycode)
+{
+    /* keycode is optional, if it is not provided use keyid */
+    if (keycode && keycode <= qemu_input_map_xorgkbd_to_qcode_len) {
+        return qemu_input_map_xorgkbd_to_qcode[keycode];
+    }
+
+    if (keyid >= 0xE000 && keyid <= 0xEFFF) {
+        keyid += 0x1000;
+    }
+
+    /* keyid is the X11 key id */
+    if (kbd_layout) {
+        keycode = keysym2scancode(kbd_layout, keyid, NULL, false);
+
+        return qemu_input_key_number_to_qcode(keycode);
+    }
+
+    return qemu_input_map_x11_to_qcode[keyid];
+}
+
+static int input_barrier_to_mouse(uint8_t buttonid)
+{
+    switch (buttonid) {
+    case barrierButtonLeft:
+        return INPUT_BUTTON_LEFT;
+    case barrierButtonMiddle:
+        return INPUT_BUTTON_MIDDLE;
+    case barrierButtonRight:
+        return INPUT_BUTTON_RIGHT;
+    case barrierButtonExtra0:
+        return INPUT_BUTTON_SIDE;
+    }
+    return buttonid;
+}
+
+#define read_char(x, p, l)           \
+do {                                 \
+    int size = sizeof(char);         \
+    if (l < size) {                  \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    x = *(char *)p;                  \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+#define read_short(x, p, l)          \
+do {                                 \
+    int size = sizeof(short);        \
+    if (l < size) {                  \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    x = ntohs(*(short *)p);          \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+#define write_short(p, x, l)         \
+do {                                 \
+    int size = sizeof(short);        \
+    if (l < size) {                  \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    *(short *)p = htons(x);          \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+#define read_int(x, p, l)            \
+do {                                 \
+    int size = sizeof(int);          \
+    if (l < size) {                  \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    x = ntohl(*(int *)p);            \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+#define write_int(p, x, l)           \
+do {                                 \
+    int size = sizeof(int);          \
+    if (l < size) {                  \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    *(int *)p = htonl(x);            \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+#define write_cmd(p, c, l)           \
+do {                                 \
+    int size = strlen(cmd_names[c]); \
+    if (l < size) {                  \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    memcpy(p, cmd_names[c], size);   \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+#define write_string(p, s, l)        \
+do {                                 \
+    int size = strlen(s);            \
+    if (l < size + sizeof(int)) {    \
+        return G_SOURCE_REMOVE;      \
+    }                                \
+    *(int *)p = htonl(size);         \
+    p += sizeof(size);               \
+    l -= sizeof(size);               \
+    memcpy(p, s, size);              \
+    p += size;                       \
+    l -= size;                       \
+} while (0)
+
+static gboolean readcmd(InputBarrier *ib, struct barrierMsg *msg)
+{
+    int ret, len, i;
+    enum barrierCmd cmd;
+    char *p;
+
+    ret = qio_channel_read(QIO_CHANNEL(ib->sioc), (char *)&len, sizeof(len),
+                           NULL);
+    if (ret < 0) {
+        return G_SOURCE_REMOVE;
+    }
+
+    len = ntohl(len);
+    if (len > MAX_HELLO_LENGTH) {
+        return G_SOURCE_REMOVE;
+    }
+
+    ret = qio_channel_read(QIO_CHANNEL(ib->sioc), ib->buffer, len, NULL);
+    if (ret < 0) {
+        return G_SOURCE_REMOVE;
+    }
+
+    p = ib->buffer;
+    if (len >= strlen(cmd_names[barrierCmdHello]) &&
+        memcmp(p, cmd_names[barrierCmdHello],
+               strlen(cmd_names[barrierCmdHello])) == 0) {
+        cmd = barrierCmdHello;
+        p += strlen(cmd_names[barrierCmdHello]);
+        len -= strlen(cmd_names[barrierCmdHello]);
+    } else {
+        for (cmd = 0; cmd < barrierCmdHello; cmd++) {
+            if (memcmp(ib->buffer, cmd_names[cmd], 4) == 0) {
+                break;
+            }
+        }
+
+        if (cmd == barrierCmdHello) {
+            return G_SOURCE_REMOVE;
+        }
+        p += 4;
+        len -= 4;
+    }
+
+    msg->cmd = cmd;
+    switch (cmd) {
+    /* connection */
+    case barrierCmdHello:
+        read_short(msg->version.major, p, len);
+        read_short(msg->version.minor, p, len);
+        break;
+    case barrierCmdDSetOptions:
+        read_int(msg->set.nb, p, len);
+        msg->set.nb /= 2;
+        if (msg->set.nb > BARRIER_MAX_OPTIONS) {
+            msg->set.nb = BARRIER_MAX_OPTIONS;
+        }
+        i = 0;
+        while (len && i < msg->set.nb) {
+            read_int(msg->set.option[i].id, p, len);
+            /* it's a string, restore endianness */
+            msg->set.option[i].id = htonl(msg->set.option[i].id);
+            msg->set.option[i].nul = 0;
+            read_int(msg->set.option[i].value, p, len);
+            i++;
+        }
+        break;
+    case barrierCmdQInfo:
+        break;
+
+    /* mouse */
+    case barrierCmdDMouseMove:
+    case barrierCmdDMouseRelMove:
+        read_short(msg->mousepos.x, p, len);
+        read_short(msg->mousepos.y, p, len);
+        break;
+    case barrierCmdDMouseDown:
+    case barrierCmdDMouseUp:
+        read_char(msg->mousebutton.buttonid, p, len);
+        break;
+    case barrierCmdDMouseWheel:
+        read_short(msg->mousepos.y, p, len);
+        msg->mousepos.x = 0;
+        if (len) {
+            msg->mousepos.x = msg->mousepos.y;
+            read_short(msg->mousepos.y, p, len);
+        }
+        break;
+
+    /* keyboard */
+    case barrierCmdDKeyDown:
+    case barrierCmdDKeyUp:
+        read_short(msg->key.keyid, p, len);
+        read_short(msg->key.modifier, p, len);
+        msg->key.button = 0;
+        if (len) {
+            read_short(msg->key.button, p, len);
+        }
+        break;
+    case barrierCmdDKeyRepeat:
+        read_short(msg->repeat.keyid, p, len);
+        read_short(msg->repeat.modifier, p, len);
+        read_short(msg->repeat.repeat, p, len);
+        msg->repeat.button = 0;
+        if (len) {
+            read_short(msg->repeat.button, p, len);
+        }
+        break;
+    case barrierCmdCInfoAck:
+    case barrierCmdCResetOptions:
+    case barrierCmdCEnter:
+    case barrierCmdDClipboard:
+    case barrierCmdCKeepAlive:
+    case barrierCmdCLeave:
+    case barrierCmdCClose:
+        break;
+
+    /* Invalid from the server */
+    case barrierCmdHelloBack:
+    case barrierCmdCNoop:
+    case barrierCmdDInfo:
+        break;
+
+    /* Error codes */
+    case barrierCmdEIncompatible:
+        read_short(msg->version.major, p, len);
+        read_short(msg->version.minor, p, len);
+        break;
+    case barrierCmdEBusy:
+    case barrierCmdEUnknown:
+    case barrierCmdEBad:
+        break;
+    default:
+        return G_SOURCE_REMOVE;
+    }
+
+    return G_SOURCE_CONTINUE;
+}
+
+static gboolean writecmd(InputBarrier *ib, struct barrierMsg *msg)
+{
+    char *p;
+    int ret, i;
+    int avail, len;
+
+    p = ib->buffer;
+    avail = MAX_HELLO_LENGTH;
+
+    /* reserve space to store the length */
+    p += sizeof(int);
+    avail -= sizeof(int);
+
+    switch (msg->cmd) {
+    case barrierCmdHello:
+        if (msg->version.major < BARRIER_VERSION_MAJOR ||
+            (msg->version.major == BARRIER_VERSION_MAJOR &&
+             msg->version.minor < BARRIER_VERSION_MINOR)) {
+            ib->ioc_tag = 0;
+            return G_SOURCE_REMOVE;
+        }
+        write_cmd(p, barrierCmdHelloBack, avail);
+        write_short(p, BARRIER_VERSION_MAJOR, avail);
+        write_short(p, BARRIER_VERSION_MINOR, avail);
+        write_string(p, ib->name, avail);
+        break;
+    case barrierCmdCClose:
+        ib->ioc_tag = 0;
+        return G_SOURCE_REMOVE;
+    case barrierCmdQInfo:
+        write_cmd(p, barrierCmdDInfo, avail);
+        write_short(p, ib->x_origin, avail);
+        write_short(p, ib->y_origin, avail);
+        write_short(p, ib->width, avail);
+        write_short(p, ib->height, avail);
+        write_short(p, 0, avail);    /* warpsize (obsolete) */
+        write_short(p, 0, avail);    /* mouse x */
+        write_short(p, 0, avail);    /* mouse y */
+        break;
+    case barrierCmdCInfoAck:
+        break;
+    case barrierCmdCResetOptions:
+        /* TODO: reset options */
+        break;
+    case barrierCmdDSetOptions:
+        /* TODO: set options */
+        break;
+    case barrierCmdCEnter:
+        break;
+    case barrierCmdDClipboard:
+        break;
+    case barrierCmdCKeepAlive:
+        write_cmd(p, barrierCmdCKeepAlive, avail);
+        break;
+    case barrierCmdCLeave:
+        break;
+
+    /* mouse */
+    case barrierCmdDMouseMove:
+        qemu_input_queue_abs(NULL, INPUT_AXIS_X, msg->mousepos.x,
+                             ib->x_origin, ib->width);
+        qemu_input_queue_abs(NULL, INPUT_AXIS_Y, msg->mousepos.y,
+                             ib->y_origin, ib->height);
+        qemu_input_event_sync();
+        break;
+    case barrierCmdDMouseRelMove:
+        qemu_input_queue_rel(NULL, INPUT_AXIS_X, msg->mousepos.x);
+        qemu_input_queue_rel(NULL, INPUT_AXIS_Y, msg->mousepos.y);
+        qemu_input_event_sync();
+        break;
+    case barrierCmdDMouseDown:
+        qemu_input_queue_btn(NULL,
+                             input_barrier_to_mouse(msg->mousebutton.buttonid),
+                             true);
+        qemu_input_event_sync();
+        break;
+    case barrierCmdDMouseUp:
+        qemu_input_queue_btn(NULL,
+                             input_barrier_to_mouse(msg->mousebutton.buttonid),
+                             false);
+        qemu_input_event_sync();
+        break;
+    case barrierCmdDMouseWheel:
+        qemu_input_queue_btn(NULL, (msg->mousepos.y > 0) ? INPUT_BUTTON_WHEEL_UP
+                             : INPUT_BUTTON_WHEEL_DOWN, true);
+        qemu_input_event_sync();
+        qemu_input_queue_btn(NULL, (msg->mousepos.y > 0) ? INPUT_BUTTON_WHEEL_UP
+                             : INPUT_BUTTON_WHEEL_DOWN, false);
+        qemu_input_event_sync();
+        break;
+
+    /* keyboard */
+    case barrierCmdDKeyDown:
+        qemu_input_event_send_key_qcode(NULL,
+                        input_barrier_to_qcode(msg->key.keyid, msg->key.button),
+                                        true);
+        break;
+    case barrierCmdDKeyRepeat:
+        for (i = 0; i < msg->repeat.repeat; i++) {
+            qemu_input_event_send_key_qcode(NULL,
+                  input_barrier_to_qcode(msg->repeat.keyid, msg->repeat.button),
+                                            false);
+            qemu_input_event_send_key_qcode(NULL,
+                  input_barrier_to_qcode(msg->repeat.keyid, msg->repeat.button),
+                                            true);
+        }
+        break;
+    case barrierCmdDKeyUp:
+        qemu_input_event_send_key_qcode(NULL,
+                        input_barrier_to_qcode(msg->key.keyid, msg->key.button),
+                                        false);
+        break;
+    default:
+        write_cmd(p, barrierCmdEUnknown, avail);
+        break;;
+    }
+
+    len = MAX_HELLO_LENGTH - avail - sizeof(int);
+    if (len) {
+        p = ib->buffer;
+        avail = sizeof(len);
+        write_int(p, len, avail);
+        ret = qio_channel_write(QIO_CHANNEL(ib->sioc), ib->buffer,
+                                len + sizeof(len), NULL);
+        if (ret < 0) {
+            ib->ioc_tag = 0;
+            return G_SOURCE_REMOVE;
+        }
+    }
+
+    return G_SOURCE_CONTINUE;
+}
+
+static gboolean input_barrier_event(QIOChannel *ioc G_GNUC_UNUSED,
+                                    GIOCondition condition, void *opaque)
+{
+    InputBarrier *ib = opaque;
+    int ret;
+    struct barrierMsg msg;
+
+    ret = readcmd(ib, &msg);
+    if (ret == G_SOURCE_REMOVE) {
+        ib->ioc_tag = 0;
+        return G_SOURCE_REMOVE;
+    }
+
+    return writecmd(ib, &msg);
+}
+
+static void input_barrier_complete(UserCreatable *uc, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(uc);
+    Error *local_err = NULL;
+
+    if (!ib->name) {
+        error_setg(errp, QERR_MISSING_PARAMETER, "name");
+        return;
+    }
+
+    /*
+     * Connect to the primary
+     * Primary is the server where the keyboard and the mouse
+     * are connected and forwarded to the secondary (the client)
+     */
+
+    ib->sioc = qio_channel_socket_new();
+    qio_channel_set_name(QIO_CHANNEL(ib->sioc), "barrier-client");
+
+    qio_channel_socket_connect_sync(ib->sioc, &ib->saddr, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    qio_channel_set_delay(QIO_CHANNEL(ib->sioc), false);
+
+    ib->ioc_tag = qio_channel_add_watch(QIO_CHANNEL(ib->sioc), G_IO_IN,
+                                        input_barrier_event, ib, NULL);
+}
+
+static void input_barrier_instance_finalize(Object *obj)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    if (ib->ioc_tag) {
+        g_source_remove(ib->ioc_tag);
+        ib->ioc_tag = 0;
+    }
+
+    if (ib->sioc) {
+        qio_channel_close(QIO_CHANNEL(ib->sioc), NULL);
+        object_unref(OBJECT(ib->sioc));
+    }
+    g_free(ib->name);
+    g_free(ib->saddr.u.inet.host);
+    g_free(ib->saddr.u.inet.port);
+}
+
+static char *input_barrier_get_name(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup(ib->name);
+}
+
+static void input_barrier_set_name(Object *obj, const char *value,
+                                  Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    if (ib->name) {
+        error_setg(errp, "name property already set");
+        return;
+    }
+    ib->name = g_strdup(value);
+}
+
+static char *input_barrier_get_server(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup(ib->saddr.u.inet.host);
+}
+
+static void input_barrier_set_server(Object *obj, const char *value,
+                                     Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    g_free(ib->saddr.u.inet.host);
+    ib->saddr.u.inet.host = g_strdup(value);
+}
+
+static char *input_barrier_get_port(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup(ib->saddr.u.inet.port);
+}
+
+static void input_barrier_set_port(Object *obj, const char *value,
+                                     Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    g_free(ib->saddr.u.inet.port);
+    ib->saddr.u.inet.port = g_strdup(value);
+}
+
+static void input_barrier_set_x_origin(Object *obj, const char *value,
+                                       Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+    int result, err;
+
+    err = qemu_strtoi(value, NULL, 0, &result);
+    if (err < 0 || result < 0 || result > SHRT_MAX) {
+        error_setg(errp,
+                   "x-origin property must be in the range [0..%d]", SHRT_MAX);
+        return;
+    }
+    ib->x_origin = result;
+}
+
+static char *input_barrier_get_x_origin(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup_printf("%d", ib->x_origin);
+}
+
+static void input_barrier_set_y_origin(Object *obj, const char *value,
+                                       Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+    int result, err;
+
+    err = qemu_strtoi(value, NULL, 0, &result);
+    if (err < 0 || result < 0 || result > SHRT_MAX) {
+        error_setg(errp,
+                   "y-origin property must be in the range [0..%d]", SHRT_MAX);
+        return;
+    }
+    ib->y_origin = result;
+}
+
+static char *input_barrier_get_y_origin(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup_printf("%d", ib->y_origin);
+}
+
+static void input_barrier_set_width(Object *obj, const char *value,
+                                       Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+    int result, err;
+
+    err = qemu_strtoi(value, NULL, 0, &result);
+    if (err < 0 || result < 0 || result > SHRT_MAX) {
+        error_setg(errp,
+                   "width property must be in the range [0..%d]", SHRT_MAX);
+        return;
+    }
+    ib->width = result;
+}
+
+static char *input_barrier_get_width(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup_printf("%d", ib->width);
+}
+
+static void input_barrier_set_height(Object *obj, const char *value,
+                                       Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+    int result, err;
+
+    err = qemu_strtoi(value, NULL, 0, &result);
+    if (err < 0 || result < 0 || result > SHRT_MAX) {
+        error_setg(errp,
+                   "height property must be in the range [0..%d]", SHRT_MAX);
+        return;
+    }
+    ib->height = result;
+}
+
+static char *input_barrier_get_height(Object *obj, Error **errp)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    return g_strdup_printf("%d", ib->height);
+}
+
+static void input_barrier_instance_init(Object *obj)
+{
+    InputBarrier *ib = INPUT_BARRIER(obj);
+
+    ib->saddr.type = SOCKET_ADDRESS_TYPE_INET;
+    ib->saddr.u.inet.host = g_strdup("localhost");
+    ib->saddr.u.inet.port = g_strdup("24800");
+
+    ib->x_origin = 0;
+    ib->y_origin = 0;
+    ib->width = 1920;
+    ib->height = 1080;
+
+    object_property_add_str(obj, "name",
+                            input_barrier_get_name,
+                            input_barrier_set_name, NULL);
+    object_property_add_str(obj, "server",
+                            input_barrier_get_server,
+                            input_barrier_set_server, NULL);
+    object_property_add_str(obj, "port",
+                            input_barrier_get_port,
+                            input_barrier_set_port, NULL);
+    object_property_add_str(obj, "x-origin",
+                            input_barrier_get_x_origin,
+                            input_barrier_set_x_origin, NULL);
+    object_property_add_str(obj, "y-origin",
+                            input_barrier_get_y_origin,
+                            input_barrier_set_y_origin, NULL);
+    object_property_add_str(obj, "width",
+                            input_barrier_get_width,
+                            input_barrier_set_width, NULL);
+    object_property_add_str(obj, "height",
+                            input_barrier_get_height,
+                            input_barrier_set_height, NULL);
+}
+
+static void input_barrier_class_init(ObjectClass *oc, void *data)
+{
+    UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
+
+    ucc->complete = input_barrier_complete;
+
+    /* always use generic keymaps */
+    if (keyboard_layout) {
+        /* We use X11 key id, so use VNC name2keysym */
+        kbd_layout = init_keyboard_layout(name2keysym, keyboard_layout,
+                                          &error_fatal);
+    }
+}
+
+static const TypeInfo input_barrier_info = {
+    .name = TYPE_INPUT_BARRIER,
+    .parent = TYPE_OBJECT,
+    .class_size = sizeof(InputBarrierClass),
+    .class_init = input_barrier_class_init,
+    .instance_size = sizeof(InputBarrier),
+    .instance_init = input_barrier_instance_init,
+    .instance_finalize = input_barrier_instance_finalize,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_USER_CREATABLE },
+        { }
+    }
+};
+
+static void register_types(void)
+{
+    type_register_static(&input_barrier_info);
+}
+
+type_init(register_types);
diff --git a/ui/input-barrier.h b/ui/input-barrier.h
new file mode 100644
index 0000000000..e5b090590a
--- /dev/null
+++ b/ui/input-barrier.h
@@ -0,0 +1,112 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef UI_INPUT_BARRIER_H
+#define UI_INPUT_BARRIER_H
+
+/* Barrier protocol */
+#define BARRIER_VERSION_MAJOR 1
+#define BARRIER_VERSION_MINOR 6
+
+enum barrierCmd {
+    barrierCmdCNoop,
+    barrierCmdCClose,
+    barrierCmdCEnter,
+    barrierCmdCLeave,
+    barrierCmdCClipboard,
+    barrierCmdCScreenSaver,
+    barrierCmdCResetOptions,
+    barrierCmdCInfoAck,
+    barrierCmdCKeepAlive,
+    barrierCmdDKeyDown,
+    barrierCmdDKeyRepeat,
+    barrierCmdDKeyUp,
+    barrierCmdDMouseDown,
+    barrierCmdDMouseUp,
+    barrierCmdDMouseMove,
+    barrierCmdDMouseRelMove,
+    barrierCmdDMouseWheel,
+    barrierCmdDClipboard,
+    barrierCmdDInfo,
+    barrierCmdDSetOptions,
+    barrierCmdDFileTransfer,
+    barrierCmdDDragInfo,
+    barrierCmdQInfo,
+    barrierCmdEIncompatible,
+    barrierCmdEBusy,
+    barrierCmdEUnknown,
+    barrierCmdEBad,
+    /* connection sequence */
+    barrierCmdHello,
+    barrierCmdHelloBack,
+};
+
+enum {
+   barrierButtonNone,
+   barrierButtonLeft,
+   barrierButtonMiddle,
+   barrierButtonRight,
+   barrierButtonExtra0
+};
+
+struct barrierVersion {
+    int16_t major;
+    int16_t minor;
+};
+
+struct barrierMouseButton {
+    int8_t buttonid;
+};
+
+struct barrierEnter {
+    int16_t x;
+    int16_t y;
+    int32_t seqn;
+    int16_t modifier;
+};
+
+struct barrierMousePos {
+    int16_t x;
+    int16_t y;
+};
+
+struct barrierKey {
+    int16_t keyid;
+    int16_t modifier;
+    int16_t button;
+};
+
+struct barrierRepeat {
+    int16_t keyid;
+    int16_t modifier;
+    int16_t repeat;
+    int16_t button;
+};
+
+#define BARRIER_MAX_OPTIONS 32
+struct barrierSet {
+    int nb;
+    struct {
+        int id;
+        char nul;
+        int value;
+    } option[BARRIER_MAX_OPTIONS];
+};
+
+struct barrierMsg {
+    enum barrierCmd cmd;
+    union {
+        struct barrierVersion version;
+        struct barrierMouseButton mousebutton;
+        struct barrierMousePos mousepos;
+        struct barrierEnter enter;
+        struct barrierKey key;
+        struct barrierRepeat repeat;
+        struct barrierSet set;
+    };
+};
+#endif