Wait SET_CLIPBOARD ack before Ctrl+v via HID

To allow seamless copy-paste, on Ctrl+v, a SET_CLIPBOARD request is
performed before injecting Ctrl+v.

But when HID keyboard is enabled, the Ctrl+v injection is not sent on
the same channel as the clipboard request, so they are not serialized,
and may occur in any order. If Ctrl+v happens to be injected before the
new clipboard content is set, then the old content is pasted instead,
which is incorrect.

To minimize the probability of occurrence of the wrong order, a delay of
2 milliseconds was added before injecting Ctrl+v. Then 5ms. But even
with 5ms, the wrong behavior sometimes happens.

To handle it properly, add an acknowledgement mechanism, so that Ctrl+v
is injected over AOA only after the SET_CLIPBOARD request has been
performed and acknowledged by the server.

Refs e4163321f0
Refs 45b0f8123a

PR #2814 <https://github.com/Genymobile/scrcpy/pull/2814>

README.md

@@ -412,12 +412,47 @@ autoadb scrcpy -s '{}'
 
 [AutoAdb]: https://github.com/rom1v/autoadb
 
-#### SSH tunnel
+#### Tunnels
 
 To connect to a remote device, it is possible to connect a local `adb` client to
 a remote `adb` server (provided they use the same version of the _adb_
 protocol).
 
+##### Remote ADB server
+
+To connect to a remote ADB server, make the server listen on all interfaces:
+
+```bash
+adb kill-server
+adb -a nodaemon server start
+# keep this open
+```
+
+**Warning: all communications between clients and ADB server are unencrypted.**
+
+Suppose that this server is accessible at 192.168.1.2. Then, from another
+terminal, run scrcpy:
+
+```bash
+export ADB_SERVER_SOCKET=tcp:192.168.1.2:5037
+scrcpy --tunnel-host=192.168.1.2
+```
+
+By default, scrcpy uses the local port used for `adb forward` tunnel
+establishment (typically `27183`, see `--port`). It is also possible to force a
+different tunnel port (it may be useful in more complex situations, when more
+redirections are involved):
+
+```
+scrcpy --tunnel-port=1234
+```
+
+
+##### SSH tunnel
+
+To communicate with a remote ADB server securely, it is preferable to use a SSH
+tunnel.
+
 First, make sure the ADB server is running on the remote computer:
 
 ```bash

app/meson.build

@@ -25,6 +25,7 @@ src = [
     'src/server.c',
     'src/stream.c',
     'src/video_buffer.c',
+    'src/util/acksync.c',
     'src/util/file.c',
     'src/util/intr.c',
     'src/util/log.c',
@@ -39,16 +40,26 @@ src = [
     'src/util/tick.c',
 ]
 
+conf = configuration_data()
+
 if host_machine.system() == 'windows'
     src += [
         'src/sys/win/file.c',
         'src/sys/win/process.c',
     ]
+    conf.set('_WIN32_WINNT', '0x0600')
+    conf.set('WINVER', '0x0600')
 else
     src += [
         'src/sys/unix/file.c',
         'src/sys/unix/process.c',
     ]
+    conf.set('_POSIX_C_SOURCE', '200809L')
+    conf.set('_XOPEN_SOURCE', '700')
+    conf.set('_GNU_SOURCE', true)
+    if host_machine.system() == 'darwin'
+        conf.set('_DARWIN_C_SOURCE', true)
+    endif
 endif
 
 v4l2_support = host_machine.system() == 'linux'
@@ -128,8 +139,6 @@ if host_machine.system() == 'windows'
     dependencies += cc.find_library('ws2_32')
 endif
 
-conf = configuration_data()
-
 foreach f : check_functions
   if cc.has_function(f)
     define = 'HAVE_' + f.underscorify().to_upper()
@@ -199,6 +208,7 @@ if get_option('buildtype') == 'debug'
             'tests/test_cli.c',
             'src/cli.c',
             'src/options.c',
+            'src/util/net.c',
             'src/util/str.c',
             'src/util/strbuf.c',
             'src/util/term.c',

app/scrcpy.1

@@ -203,6 +203,18 @@ Enable "show touches" on start, restore the initial value on exit.
 
 It only shows physical touches (not clicks from scrcpy).
 
+.TP
+.BI "\-\-tunnel\-host " ip
+Set the IP address of the adb tunnel to reach the scrcpy server. This option automatically enables --force-adb-forward.
+
+Default is localhost.
+
+.TP
+.BI "\-\-tunnel\-port " port
+Set the TCP port of the adb tunnel to reach the scrcpy server. This option automatically enables --force-adb-forward.
+
+Default is 0 (not forced): the local port used for establishing the tunnel will be used.
+
 .TP
 .BI "\-\-v4l2-sink " /dev/videoN
 Output to v4l2loopback device.

app/src/aoa_hid.c

@@ -35,7 +35,7 @@ sc_hid_event_init(struct sc_hid_event *hid_event, uint16_t accessory_id,
     hid_event->accessory_id = accessory_id;
     hid_event->buffer = buffer;
     hid_event->size = buffer_size;
-    hid_event->delay = 0;
+    hid_event->ack_to_wait = SC_SEQUENCE_INVALID;
 }
 
 void
@@ -118,7 +118,10 @@ sc_aoa_open_usb_handle(libusb_device *device, libusb_device_handle **handle) {
 }
 
 bool
-sc_aoa_init(struct sc_aoa *aoa, const char *serial) {
+sc_aoa_init(struct sc_aoa *aoa, const char *serial,
+            struct sc_acksync *acksync) {
+    assert(acksync);
+
     cbuf_init(&aoa->queue);
 
     if (!sc_mutex_init(&aoa->mutex)) {
@@ -155,6 +158,7 @@ sc_aoa_init(struct sc_aoa *aoa, const char *serial) {
     }
 
     aoa->stopped = false;
+    aoa->acksync = acksync;
 
     return true;
 }
@@ -332,23 +336,28 @@ run_aoa_thread(void *data) {
         assert(non_empty);
         (void) non_empty;
 
-        assert(event.delay >= 0);
+        uint64_t ack_to_wait = event.ack_to_wait;
-        if (event.delay) {
-            // Wait during the specified delay before injecting the HID event
-            sc_tick deadline = sc_tick_now() + event.delay;
-            bool timed_out = false;
-            while (!aoa->stopped && !timed_out) {
-                timed_out = !sc_cond_timedwait(&aoa->event_cond, &aoa->mutex,
-                                               deadline);
-            }
-            if (aoa->stopped) {
         sc_mutex_unlock(&aoa->mutex);
+
+        if (ack_to_wait != SC_SEQUENCE_INVALID) {
+            LOGD("Waiting ack from server sequence=%" PRIu64_, ack_to_wait);
+            // Do not block the loop indefinitely if the ack never comes (it should
+            // never happen)
+            sc_tick deadline = sc_tick_now() + SC_TICK_FROM_MS(500);
+            enum sc_acksync_wait_result result =
+                sc_acksync_wait(aoa->acksync, ack_to_wait, deadline);
+
+            if (result == SC_ACKSYNC_WAIT_TIMEOUT) {
+                LOGW("Ack not received after 500ms, discarding HID event");
+                sc_hid_event_destroy(&event);
+                continue;
+            } else if (result == SC_ACKSYNC_WAIT_INTR) {
+                // stopped
+                sc_hid_event_destroy(&event);
                 break;
             }
         }
 
-        sc_mutex_unlock(&aoa->mutex);
-
         bool ok = sc_aoa_send_hid_event(aoa, &event);
         sc_hid_event_destroy(&event);
         if (!ok) {
@@ -377,6 +386,8 @@ sc_aoa_stop(struct sc_aoa *aoa) {
     aoa->stopped = true;
     sc_cond_signal(&aoa->event_cond);
     sc_mutex_unlock(&aoa->mutex);
+
+    sc_acksync_interrupt(aoa->acksync);
 }
 
 void

app/src/aoa_hid.h

@@ -6,6 +6,7 @@
 
 #include <libusb-1.0/libusb.h>
 
+#include "util/acksync.h"
 #include "util/cbuf.h"
 #include "util/thread.h"
 #include "util/tick.h"
@@ -14,7 +15,7 @@ struct sc_hid_event {
     uint16_t accessory_id;
     unsigned char *buffer;
     uint16_t size;
-    sc_tick delay;
+    uint64_t ack_to_wait;
 };
 
 // Takes ownership of buffer
@@ -36,10 +37,12 @@ struct sc_aoa {
     sc_cond event_cond;
     bool stopped;
     struct sc_hid_event_queue queue;
+
+    struct sc_acksync *acksync;
 };
 
 bool
-sc_aoa_init(struct sc_aoa *aoa, const char *serial);
+sc_aoa_init(struct sc_aoa *aoa, const char *serial, struct sc_acksync *acksync);
 
 void
 sc_aoa_destroy(struct sc_aoa *aoa);

app/src/cli.c

@@ -9,6 +9,7 @@
 
 #include "options.h"
 #include "util/log.h"
+#include "util/net.h"
 #include "util/str.h"
 #include "util/strbuf.h"
 #include "util/term.h"
@@ -46,6 +47,8 @@
 #define OPT_V4L2_SINK              1027
 #define OPT_DISPLAY_BUFFER         1028
 #define OPT_V4L2_BUFFER            1029
+#define OPT_TUNNEL_HOST            1030
+#define OPT_TUNNEL_PORT            1031
 
 struct sc_option {
     char shortopt;
@@ -330,6 +333,25 @@ static const struct sc_option options[] = {
                 "on exit.\n"
                 "It only shows physical touches (not clicks from scrcpy).",
     },
+    {
+        .longopt_id = OPT_TUNNEL_HOST,
+        .longopt = "tunnel-host",
+        .argdesc = "ip",
+        .text = "Set the IP address of the adb tunnel to reach the scrcpy "
+                "server. This option automatically enables "
+                "--force-adb-forward.\n"
+                "Default is localhost.",
+    },
+    {
+        .longopt_id = OPT_TUNNEL_PORT,
+        .longopt = "tunnel-port",
+        .argdesc = "port",
+        .text = "Set the TCP port of the adb tunnel to reach the scrcpy "
+                "server. This option automatically enables "
+                "--force-adb-forward.\n"
+                "Default is 0 (not forced): the local port used for "
+                "establishing the tunnel will be used.",
+    },
 #ifdef HAVE_V4L2
     {
         .longopt_id = OPT_V4L2_SINK,
@@ -1127,6 +1149,21 @@ parse_record_format(const char *optarg, enum sc_record_format *format) {
     return false;
 }
 
+static bool
+parse_ip(const char *optarg, uint32_t *ipv4) {
+    return net_parse_ipv4(optarg, ipv4);
+}
+
+static bool
+parse_port(const char *optarg, uint16_t *port) {
+    long value;
+    if (!parse_integer_arg(optarg, &value, false, 0, 0xFFFF, "port")) {
+        return false;
+    }
+    *port = (uint16_t) value;
+    return true;
+}
+
 static enum sc_record_format
 guess_record_format(const char *filename) {
     size_t len = strlen(filename);
@@ -1199,6 +1236,16 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
                     return false;
                 }
                 break;
+            case OPT_TUNNEL_HOST:
+                if (!parse_ip(optarg, &opts->tunnel_host)) {
+                    return false;
+                }
+                break;
+            case OPT_TUNNEL_PORT:
+                if (!parse_port(optarg, &opts->tunnel_port)) {
+                    return false;
+                }
+                break;
             case 'n':
                 opts->control = false;
                 break;
@@ -1358,6 +1405,12 @@ parse_args_with_getopt(struct scrcpy_cli_args *args, int argc, char *argv[],
     }
 #endif
 
+    if ((opts->tunnel_host || opts->tunnel_port) && !opts->force_adb_forward) {
+        LOGI("Tunnel host/port is set, "
+             "--force-adb-forward automatically enabled.");
+        opts->force_adb_forward = true;
+    }
+
     int index = optind;
     if (index < argc) {
         LOGE("Unexpected additional argument: %s", argv[index]);

app/src/compat.h

@@ -1,16 +1,17 @@
 #ifndef COMPAT_H
 #define COMPAT_H
 
-#define _POSIX_C_SOURCE 200809L
+#include "config.h"
-#define _XOPEN_SOURCE 700
-#define _GNU_SOURCE
-#ifdef __APPLE__
-# define _DARWIN_C_SOURCE
-#endif
 
 #include <libavformat/version.h>
 #include <SDL2/SDL_version.h>
 
+#ifndef __WIN32
+# define PRIu64_ PRIu64
+#else
+# define PRIu64_ "I64u"  // Windows...
+#endif
+
 // In ffmpeg/doc/APIchanges:
 // 2018-02-06 - 0694d87024 - lavf 58.9.100 - avformat.h
 //   Deprecate use of av_register_input_format(), av_register_output_format(),

app/src/control_msg.c

@@ -118,11 +118,12 @@ control_msg_serialize(const struct control_msg *msg, unsigned char *buf) {
             buf[1] = msg->inject_keycode.action;
             return 2;
         case CONTROL_MSG_TYPE_SET_CLIPBOARD: {
-            buf[1] = !!msg->set_clipboard.paste;
+            buffer_write64be(&buf[1], msg->set_clipboard.sequence);
+            buf[9] = !!msg->set_clipboard.paste;
             size_t len = write_string(msg->set_clipboard.text,
                                       CONTROL_MSG_CLIPBOARD_TEXT_MAX_LENGTH,
-                                      &buf[2]);
+                                      &buf[10]);
-            return 2 + len;
+            return 10 + len;
         }
         case CONTROL_MSG_TYPE_SET_SCREEN_POWER_MODE:
             buf[1] = msg->set_screen_power_mode.mode;
@@ -170,11 +171,6 @@ control_msg_log(const struct control_msg *msg) {
                          (long) msg->inject_touch_event.buttons);
             } else {
                 // numeric pointer id
-#ifndef __WIN32
-# define PRIu64_ PRIu64
-#else
-# define PRIu64_ "I64u"  // Windows...
-#endif
                 LOG_CMSG("touch [id=%" PRIu64_ "] %-4s position=%" PRIi32 ",%"
                              PRIi32 " pressure=%g buttons=%06lx",
                          id,
@@ -199,7 +195,8 @@ control_msg_log(const struct control_msg *msg) {
                      KEYEVENT_ACTION_LABEL(msg->inject_keycode.action));
             break;
         case CONTROL_MSG_TYPE_SET_CLIPBOARD:
-            LOG_CMSG("clipboard %s \"%s\"",
+            LOG_CMSG("clipboard %" PRIu64_ " %s \"%s\"",
+                     msg->set_clipboard.sequence,
                      msg->set_clipboard.paste ? "paste" : "copy",
                      msg->set_clipboard.text);
             break;

app/src/control_msg.h

@@ -70,6 +70,7 @@ struct control_msg {
             // screen may only be turned on on ACTION_DOWN
         } back_or_screen_on;
         struct {
+            uint64_t sequence;
             char *text; // owned, to be freed by free()
             bool paste;
         } set_clipboard;

app/src/controller.c

@@ -5,10 +5,11 @@
 #include "util/log.h"
 
 bool
-controller_init(struct controller *controller, sc_socket control_socket) {
+controller_init(struct controller *controller, sc_socket control_socket,
+                struct sc_acksync *acksync) {
     cbuf_init(&controller->queue);
 
-    bool ok = receiver_init(&controller->receiver, control_socket);
+    bool ok = receiver_init(&controller->receiver, control_socket, acksync);
     if (!ok) {
         return false;
     }

app/src/controller.h

@@ -7,6 +7,7 @@
 
 #include "control_msg.h"
 #include "receiver.h"
+#include "util/acksync.h"
 #include "util/cbuf.h"
 #include "util/net.h"
 #include "util/thread.h"
@@ -24,7 +25,8 @@ struct controller {
 };
 
 bool
-controller_init(struct controller *controller, sc_socket control_socket);
+controller_init(struct controller *controller, sc_socket control_socket,
+                struct sc_acksync *acksync);
 
 void
 controller_destroy(struct controller *controller);

app/src/device_msg.c

@@ -1,5 +1,6 @@
 #include "device_msg.h"
 
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -34,6 +35,11 @@ device_msg_deserialize(const unsigned char *buf, size_t len,
             msg->clipboard.text = text;
             return 5 + clipboard_len;
         }
+        case DEVICE_MSG_TYPE_ACK_CLIPBOARD: {
+            uint64_t sequence = buffer_read64be(&buf[1]);
+            msg->ack_clipboard.sequence = sequence;
+            return 9;
+        }
         default:
             LOGW("Unknown device message type: %d", (int) msg->type);
             return -1; // error, we cannot recover

app/src/device_msg.h

@@ -13,6 +13,7 @@
 
 enum device_msg_type {
     DEVICE_MSG_TYPE_CLIPBOARD,
+    DEVICE_MSG_TYPE_ACK_CLIPBOARD,
 };
 
 struct device_msg {
@@ -21,6 +22,9 @@ struct device_msg {
         struct {
             char *text; // owned, to be freed by free()
         } clipboard;
+        struct {
+            uint64_t sequence;
+        } ack_clipboard;
     };
 };
 

app/src/hid_keyboard.c

@@ -278,7 +278,8 @@ push_mod_lock_state(struct sc_hid_keyboard *kb, uint16_t sdl_mod) {
 
 static void
 sc_key_processor_process_key(struct sc_key_processor *kp,
-                             const SDL_KeyboardEvent *event) {
+                             const SDL_KeyboardEvent *event,
+                             uint64_t ack_to_wait) {
     if (event->repeat) {
         // In USB HID protocol, key repeat is handled by the host (Android), so
         // just ignore key repeat here.
@@ -298,16 +299,12 @@ sc_key_processor_process_key(struct sc_key_processor *kp,
             }
         }
 
-        SDL_Keycode keycode = event->keysym.sym;
+        if (ack_to_wait) {
-        bool down = event->type == SDL_KEYDOWN;
-        bool ctrl = event->keysym.mod & KMOD_CTRL;
-        bool shift = event->keysym.mod & KMOD_SHIFT;
-        if (ctrl && !shift && keycode == SDLK_v && down) {
             // Ctrl+v is pressed, so clipboard synchronization has been
-            // requested. Wait a bit so that the clipboard is set before
+            // requested. Wait until clipboard synchronization is acknowledged
-            // injecting Ctrl+v via HID, otherwise it would paste the old
+            // by the server, otherwise it could paste the old clipboard
-            // clipboard content.
+            // content.
-            hid_event.delay = SC_TICK_FROM_MS(5);
+            hid_event.ack_to_wait = ack_to_wait;
         }
 
         if (!sc_aoa_push_hid_event(kb->aoa, &hid_event)) {
@@ -348,6 +345,10 @@ sc_hid_keyboard_init(struct sc_hid_keyboard *kb, struct sc_aoa *aoa) {
         .process_text = sc_key_processor_process_text,
     };
 
+    // Clipboard synchronization is requested over the control socket, while HID
+    // events are sent over AOA, so it must wait for clipboard synchronization
+    // to be acknowledged by the device before injecting Ctrl+v.
+    kb->key_processor.async_paste = true;
     kb->key_processor.ops = &ops;
 
     return true;

app/src/input_manager.c

@@ -82,6 +82,8 @@ input_manager_init(struct input_manager *im, struct controller *controller,
     im->last_keycode = SDLK_UNKNOWN;
     im->last_mod = 0;
     im->key_repeat = 0;
+
+    im->next_sequence = 1; // 0 is reserved for SC_SEQUENCE_INVALID
 }
 
 static void
@@ -208,35 +210,35 @@ collapse_panels(struct controller *controller) {
     }
 }
 
-static void
+static bool
-set_device_clipboard(struct controller *controller, bool paste) {
+set_device_clipboard(struct controller *controller, bool paste,
+                     uint64_t sequence) {
     char *text = SDL_GetClipboardText();
     if (!text) {
         LOGW("Could not get clipboard text: %s", SDL_GetError());
-        return;
+        return false;
-    }
-    if (!*text) {
-        // empty text
-        SDL_free(text);
-        return;
     }
 
     char *text_dup = strdup(text);
     SDL_free(text);
     if (!text_dup) {
         LOGW("Could not strdup input text");
-        return;
+        return false;
     }
 
     struct control_msg msg;
     msg.type = CONTROL_MSG_TYPE_SET_CLIPBOARD;
+    msg.set_clipboard.sequence = sequence;
     msg.set_clipboard.text = text_dup;
     msg.set_clipboard.paste = paste;
 
     if (!controller_push_msg(controller, &msg)) {
         free(text_dup);
         LOGW("Could not request 'set device clipboard'");
+        return false;
     }
+
+    return true;
 }
 
 static void
@@ -462,8 +464,10 @@ input_manager_process_key(struct input_manager *im,
                         // inject the text as input events
                         clipboard_paste(controller);
                     } else {
-                        // store the text in the device clipboard and paste
+                        // store the text in the device clipboard and paste,
-                        set_device_clipboard(controller, true);
+                        // without requesting an acknowledgment
+                        set_device_clipboard(controller, true,
+                                             SC_SEQUENCE_INVALID);
                     }
                 }
                 return;
@@ -512,18 +516,36 @@ input_manager_process_key(struct input_manager *im,
         return;
     }
 
-    if (ctrl && !shift && keycode == SDLK_v && down && !repeat) {
+    uint64_t ack_to_wait = SC_SEQUENCE_INVALID;
+    bool is_ctrl_v = ctrl && !shift && keycode == SDLK_v && down && !repeat;
+    if (is_ctrl_v) {
         if (im->legacy_paste) {
             // inject the text as input events
             clipboard_paste(controller);
             return;
         }
+
+        // Request an acknowledgement only if necessary
+        uint64_t sequence = im->kp->async_paste ? im->next_sequence
+                                                : SC_SEQUENCE_INVALID;
+
         // Synchronize the computer clipboard to the device clipboard before
         // sending Ctrl+v, to allow seamless copy-paste.
-        set_device_clipboard(controller, false);
+        bool ok = set_device_clipboard(controller, false, sequence);
+        if (!ok) {
+            LOGW("Clipboard could not be synchronized, Ctrl+v not injected");
+            return;
         }
 
-    im->kp->ops->process_key(im->kp, event);
+        if (im->kp->async_paste) {
+            // The key processor must wait for this ack before injecting Ctrl+v
+            ack_to_wait = sequence;
+            // Increment only when the request succeeded
+            ++im->next_sequence;
+        }
+    }
+
+    im->kp->ops->process_key(im->kp, event, ack_to_wait);
 }
 
 static void

app/src/input_manager.h

@@ -38,6 +38,8 @@ struct input_manager {
     unsigned key_repeat;
     SDL_Keycode last_keycode;
     uint16_t last_mod;
+
+    uint64_t next_sequence; // used for request acknowledgements
 };
 
 void

app/src/keyboard_inject.c

@@ -188,7 +188,13 @@ convert_input_key(const SDL_KeyboardEvent *from, struct control_msg *to,
 
 static void
 sc_key_processor_process_key(struct sc_key_processor *kp,
-                             const SDL_KeyboardEvent *event) {
+                             const SDL_KeyboardEvent *event,
+                             uint64_t ack_to_wait) {
+    // The device clipboard synchronization and the key event messages are
+    // serialized, there is nothing special to do to ensure that the clipboard
+    // is set before injecting Ctrl+v.
+    (void) ack_to_wait;
+
     struct sc_keyboard_inject *ki = DOWNCAST(kp);
 
     if (event->repeat) {
@@ -250,5 +256,7 @@ sc_keyboard_inject_init(struct sc_keyboard_inject *ki,
         .process_text = sc_key_processor_process_text,
     };
 
+    // Key injection and clipboard synchronization are serialized
+    ki->key_processor.async_paste = false;
     ki->key_processor.ops = &ops;
 }

app/src/options.c

@@ -19,6 +19,8 @@ const struct scrcpy_options scrcpy_options_default = {
         .first = DEFAULT_LOCAL_PORT_RANGE_FIRST,
         .last = DEFAULT_LOCAL_PORT_RANGE_LAST,
     },
+    .tunnel_host = 0,
+    .tunnel_port = 0,
     .shortcut_mods = {
         .data = {SC_MOD_LALT, SC_MOD_LSUPER},
         .count = 2,

app/src/options.h

@@ -77,6 +77,8 @@ struct scrcpy_options {
     enum sc_record_format record_format;
     enum sc_keyboard_input_mode keyboard_input_mode;
     struct sc_port_range port_range;
+    uint32_t tunnel_host;
+    uint16_t tunnel_port;
     struct sc_shortcut_mods shortcut_mods;
     uint16_t max_size;
     uint32_t bit_rate;

app/src/receiver.c

@@ -7,12 +7,16 @@
 #include "util/log.h"
 
 bool
-receiver_init(struct receiver *receiver, sc_socket control_socket) {
+receiver_init(struct receiver *receiver, sc_socket control_socket,
+              struct sc_acksync *acksync) {
     bool ok = sc_mutex_init(&receiver->mutex);
     if (!ok) {
         return false;
     }
+
     receiver->control_socket = control_socket;
+    receiver->acksync = acksync;
+
     return true;
 }
 
@@ -22,7 +26,7 @@ receiver_destroy(struct receiver *receiver) {
 }
 
 static void
-process_msg(struct device_msg *msg) {
+process_msg(struct receiver *receiver, struct device_msg *msg) {
     switch (msg->type) {
         case DEVICE_MSG_TYPE_CLIPBOARD: {
             char *current = SDL_GetClipboardText();
@@ -37,11 +41,17 @@ process_msg(struct device_msg *msg) {
             SDL_SetClipboardText(msg->clipboard.text);
             break;
         }
+        case DEVICE_MSG_TYPE_ACK_CLIPBOARD:
+            assert(receiver->acksync);
+            LOGD("Ack device clipboard sequence=%" PRIu64_,
+                 msg->ack_clipboard.sequence);
+            sc_acksync_ack(receiver->acksync, msg->ack_clipboard.sequence);
+            break;
     }
 }
 
 static ssize_t
-process_msgs(const unsigned char *buf, size_t len) {
+process_msgs(struct receiver *receiver, const unsigned char *buf, size_t len) {
     size_t head = 0;
     for (;;) {
         struct device_msg msg;
@@ -53,7 +63,7 @@ process_msgs(const unsigned char *buf, size_t len) {
             return head;
         }
 
-        process_msg(&msg);
+        process_msg(receiver, &msg);
         device_msg_destroy(&msg);
 
         head += r;
@@ -81,7 +91,7 @@ run_receiver(void *data) {
         }
 
         head += r;
-        ssize_t consumed = process_msgs(buf, head);
+        ssize_t consumed = process_msgs(receiver, buf, head);
         if (consumed == -1) {
             // an error occurred
             break;

app/src/receiver.h

@@ -5,6 +5,7 @@
 
 #include <stdbool.h>
 
+#include "util/acksync.h"
 #include "util/net.h"
 #include "util/thread.h"
 
@@ -14,10 +15,13 @@ struct receiver {
     sc_socket control_socket;
     sc_thread thread;
     sc_mutex mutex;
+
+    struct sc_acksync *acksync;
 };
 
 bool
-receiver_init(struct receiver *receiver, sc_socket control_socket);
+receiver_init(struct receiver *receiver, sc_socket control_socket,
+              struct sc_acksync *acksync);
 
 void
 receiver_destroy(struct receiver *receiver);

app/src/scrcpy.c

@@ -27,6 +27,7 @@
 #include "screen.h"
 #include "server.h"
 #include "stream.h"
+#include "util/acksync.h"
 #include "util/log.h"
 #include "util/net.h"
 #ifdef HAVE_V4L2
@@ -46,6 +47,8 @@ struct scrcpy {
     struct file_handler file_handler;
 #ifdef HAVE_AOA_HID
     struct sc_aoa aoa;
+    // sequence/ack helper to synchronize clipboard and Ctrl+v via HID
+    struct sc_acksync acksync;
 #endif
     union {
         struct sc_keyboard_inject keyboard_inject;
@@ -340,11 +343,15 @@ scrcpy(struct scrcpy_options *options) {
     bool controller_started = false;
     bool screen_initialized = false;
 
+    struct sc_acksync *acksync = NULL;
+
     struct sc_server_params params = {
         .serial = options->serial,
         .log_level = options->log_level,
         .crop = options->crop,
         .port_range = options->port_range,
+        .tunnel_host = options->tunnel_host,
+        .tunnel_port = options->tunnel_port,
         .max_size = options->max_size,
         .bit_rate = options->bit_rate,
         .max_fps = options->max_fps,
@@ -443,7 +450,18 @@ scrcpy(struct scrcpy_options *options) {
     }
 
     if (options->control) {
-        if (!controller_init(&s->controller, s->server.control_socket)) {
+#ifdef HAVE_AOA_HID
+        if (options->keyboard_input_mode == SC_KEYBOARD_INPUT_MODE_HID) {
+            bool ok = sc_acksync_init(&s->acksync);
+            if (!ok) {
+                goto end;
+            }
+
+            acksync = &s->acksync;
+        }
+#endif
+        if (!controller_init(&s->controller, s->server.control_socket,
+                             acksync)) {
             goto end;
         }
         controller_initialized = true;
@@ -519,7 +537,7 @@ scrcpy(struct scrcpy_options *options) {
 #ifdef HAVE_AOA_HID
             bool aoa_hid_ok = false;
 
-            bool ok = sc_aoa_init(&s->aoa, serial);
+            bool ok = sc_aoa_init(&s->aoa, serial, acksync);
             if (!ok) {
                 goto aoa_hid_end;
             }
@@ -584,6 +602,9 @@ end:
         sc_hid_keyboard_destroy(&s->keyboard_hid);
         sc_aoa_stop(&s->aoa);
     }
+    if (acksync) {
+        sc_acksync_destroy(acksync);
+    }
 #endif
     if (controller_started) {
         controller_stop(&s->controller);

app/src/server.c

@@ -202,8 +202,9 @@ execute_server(struct sc_server *server,
 }
 
 static bool
-connect_and_read_byte(struct sc_intr *intr, sc_socket socket, uint16_t port) {
+connect_and_read_byte(struct sc_intr *intr, sc_socket socket,
-    bool ok = net_connect_intr(intr, socket, IPV4_LOCALHOST, port);
+                      uint32_t tunnel_host, uint16_t tunnel_port) {
+    bool ok = net_connect_intr(intr, socket, tunnel_host, tunnel_port);
     if (!ok) {
         return false;
     }
@@ -220,13 +221,13 @@ connect_and_read_byte(struct sc_intr *intr, sc_socket socket, uint16_t port) {
 }
 
 static sc_socket
-connect_to_server(struct sc_server *server, uint32_t attempts, sc_tick delay) {
+connect_to_server(struct sc_server *server, uint32_t attempts, sc_tick delay,
-    uint16_t port = server->tunnel.local_port;
+                  uint32_t host, uint16_t port) {
     do {
         LOGD("Remaining connection attempts: %d", (int) attempts);
         sc_socket socket = net_socket();
         if (socket != SC_SOCKET_NONE) {
-            bool ok = connect_and_read_byte(&server->intr, socket, port);
+            bool ok = connect_and_read_byte(&server->intr, socket, host, port);
             if (ok) {
                 // it worked!
                 return socket;
@@ -352,9 +353,20 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
             goto fail;
         }
     } else {
+        uint32_t tunnel_host = server->params.tunnel_host;
+        if (!tunnel_host) {
+            tunnel_host = IPV4_LOCALHOST;
+        }
+
+        uint16_t tunnel_port = server->params.tunnel_port;
+        if (!tunnel_port) {
+            tunnel_port = tunnel->local_port;
+        }
+
         uint32_t attempts = 100;
         sc_tick delay = SC_TICK_FROM_MS(100);
-        video_socket = connect_to_server(server, attempts, delay);
+        video_socket = connect_to_server(server, attempts, delay, tunnel_host,
+                                         tunnel_port);
         if (video_socket == SC_SOCKET_NONE) {
             goto fail;
         }
@@ -364,8 +376,8 @@ sc_server_connect_to(struct sc_server *server, struct sc_server_info *info) {
         if (control_socket == SC_SOCKET_NONE) {
             goto fail;
         }
-        bool ok = net_connect_intr(&server->intr, control_socket,
+        bool ok = net_connect_intr(&server->intr, control_socket, tunnel_host,
-                                   IPV4_LOCALHOST, tunnel->local_port);
+                                   tunnel_port);
         if (!ok) {
             goto fail;
         }

app/src/server.h

@@ -29,6 +29,8 @@ struct sc_server_params {
     const char *codec_options;
     const char *encoder_name;
     struct sc_port_range port_range;
+    uint32_t tunnel_host;
+    uint16_t tunnel_port;
     uint16_t max_size;
     uint32_t bit_rate;
     uint16_t max_fps;

app/src/sys/win/process.c

@@ -1,6 +1,3 @@
-// <https://devblogs.microsoft.com/oldnewthing/20111216-00/?p=8873>
-#define _WIN32_WINNT 0x0600 // For extended process API
-
 #include "util/process.h"
 
 #include <processthreadsapi.h>

app/src/trait/key_processor.h

@@ -14,12 +14,31 @@
  * Component able to process and inject keys should implement this trait.
  */
 struct sc_key_processor {
+    /**
+     * Set by the implementation to indicate that it must explicitly wait for
+     * the clipboard to be set on the device before injecting Ctrl+v to avoid
+     * race conditions. If it is set, the input_manager will pass a valid
+     * ack_to_wait to process_key() in case of clipboard synchronization
+     * resulting of the key event.
+     */
+    bool async_paste;
+
     const struct sc_key_processor_ops *ops;
 };
 
 struct sc_key_processor_ops {
+
+    /**
+     * Process the keyboard event
+     *
+     * The `sequence` number (if different from `SC_SEQUENCE_INVALID`) indicates
+     * the acknowledgement number to wait for before injecting this event.
+     * This allows to ensure that the device clipboard is set before injecting
+     * Ctrl+v on the device.
+     */
     void
-    (*process_key)(struct sc_key_processor *kp, const SDL_KeyboardEvent *event);
+    (*process_key)(struct sc_key_processor *kp, const SDL_KeyboardEvent *event,
+                   uint64_t ack_to_wait);
 
     void
     (*process_text)(struct sc_key_processor *kp,

app/src/util/acksync.c

@@ -0,0 +1,76 @@
+#include "acksync.h"
+
+#include <assert.h>
+#include "util/log.h"
+
+bool
+sc_acksync_init(struct sc_acksync *as) {
+    bool ok = sc_mutex_init(&as->mutex);
+    if (!ok) {
+        return false;
+    }
+
+    ok = sc_cond_init(&as->cond);
+    if (!ok) {
+        sc_mutex_destroy(&as->mutex);
+        return false;
+    }
+
+    as->stopped = false;
+    as->ack = SC_SEQUENCE_INVALID;
+
+    return true;
+}
+
+void
+sc_acksync_destroy(struct sc_acksync *as) {
+    sc_cond_destroy(&as->cond);
+    sc_mutex_destroy(&as->mutex);
+}
+
+void
+sc_acksync_ack(struct sc_acksync *as, uint64_t sequence) {
+    sc_mutex_lock(&as->mutex);
+
+    // Acknowledgements must be monotonic
+    assert(sequence >= as->ack);
+
+    as->ack = sequence;
+    sc_cond_signal(&as->cond);
+
+    sc_mutex_unlock(&as->mutex);
+}
+
+enum sc_acksync_wait_result
+sc_acksync_wait(struct sc_acksync *as, uint64_t ack, sc_tick deadline) {
+    sc_mutex_lock(&as->mutex);
+
+    bool timed_out = false;
+    while (!as->stopped && as->ack < ack && !timed_out) {
+        timed_out = !sc_cond_timedwait(&as->cond, &as->mutex, deadline);
+    }
+
+    enum sc_acksync_wait_result ret;
+    if (as->stopped) {
+        ret = SC_ACKSYNC_WAIT_INTR;
+    } else if (as->ack >= ack) {
+        ret = SC_ACKSYNC_WAIT_OK;
+    } else {
+        assert(timed_out);
+        ret = SC_ACKSYNC_WAIT_TIMEOUT;
+    }
+    sc_mutex_unlock(&as->mutex);
+
+    return ret;
+}
+
+/**
+ * Interrupt any `sc_acksync_wait()`
+ */
+void
+sc_acksync_interrupt(struct sc_acksync *as) {
+    sc_mutex_lock(&as->mutex);
+    as->stopped = true;
+    sc_cond_signal(&as->cond);
+    sc_mutex_unlock(&as->mutex);
+}

app/src/util/acksync.h

@@ -0,0 +1,66 @@
+#ifndef SC_ACK_SYNC_H
+#define SC_ACK_SYNC_H
+
+#include "common.h"
+
+#include "thread.h"
+
+#define SC_SEQUENCE_INVALID 0
+
+/**
+ * Helper to wait for acknowledgments
+ *
+ * In practice, it is used to wait for device clipboard acknowledgement from the
+ * server before injecting Ctrl+v via AOA HID, in order to avoid pasting the
+ * content of the old device clipboard (if Ctrl+v was injected before the
+ * clipboard content was actually set).
+ */
+struct sc_acksync {
+    sc_mutex mutex;
+    sc_cond cond;
+
+    bool stopped;
+
+    // Last acked value, initially SC_SEQUENCE_INVALID
+    uint64_t ack;
+};
+
+enum sc_acksync_wait_result {
+    // Acknowledgment received
+    SC_ACKSYNC_WAIT_OK,
+
+    // Timeout expired
+    SC_ACKSYNC_WAIT_TIMEOUT,
+
+    // Interrupted from another thread by sc_acksync_interrupt()
+    SC_ACKSYNC_WAIT_INTR,
+};
+
+bool
+sc_acksync_init(struct sc_acksync *as);
+
+void
+sc_acksync_destroy(struct sc_acksync *as);
+
+/**
+ * Acknowledge `sequence`
+ *
+ * The `sequence` must be greater than (or equal to) any previous acknowledged
+ * sequence.
+ */
+void
+sc_acksync_ack(struct sc_acksync *as, uint64_t sequence);
+
+/**
+ * Wait for acknowledgment of sequence `ack` (or higher)
+ */
+enum sc_acksync_wait_result
+sc_acksync_wait(struct sc_acksync *as, uint64_t ack, sc_tick deadline);
+
+/**
+ * Interrupt any `sc_acksync_wait()`
+ */
+void
+sc_acksync_interrupt(struct sc_acksync *as);
+
+#endif

app/src/util/net.c

@@ -7,6 +7,7 @@
 #include "log.h"
 
 #ifdef __WINDOWS__
+# include <ws2tcpip.h>
   typedef int socklen_t;
   typedef SOCKET sc_raw_socket;
 #else
@@ -225,3 +226,15 @@ net_close(sc_socket socket) {
     return !close(raw_sock);
 #endif
 }
+
+bool
+net_parse_ipv4(const char *s, uint32_t *ipv4) {
+    struct in_addr addr;
+    if (!inet_pton(AF_INET, s, &addr)) {
+        LOGE("Invalid IPv4 address: %s", s);
+        return false;
+    }
+
+    *ipv4 = ntohl(addr.s_addr);
+    return true;
+}

app/src/util/net.h

@@ -68,4 +68,10 @@ net_interrupt(sc_socket socket);
 bool
 net_close(sc_socket socket);
 
+/**
+ * Parse `ip` "xxx.xxx.xxx.xxx" to an IPv4 host representation
+ */
+bool
+net_parse_ipv4(const char *ip, uint32_t *ipv4);
+
 #endif

app/tests/test_control_msg_serialize.c

@@ -78,7 +78,7 @@ static void test_serialize_inject_touch_event(void) {
         .type = CONTROL_MSG_TYPE_INJECT_TOUCH_EVENT,
         .inject_touch_event = {
             .action = AMOTION_EVENT_ACTION_DOWN,
-            .pointer_id = 0x1234567887654321L,
+            .pointer_id = UINT64_C(0x1234567887654321),
             .position = {
                 .point = {
                     .x = 100,
@@ -226,6 +226,7 @@ static void test_serialize_set_clipboard(void) {
     struct control_msg msg = {
         .type = CONTROL_MSG_TYPE_SET_CLIPBOARD,
         .set_clipboard = {
+            .sequence = UINT64_C(0x0102030405060708),
             .paste = true,
             .text = "hello, world!",
         },
@@ -233,10 +234,11 @@ static void test_serialize_set_clipboard(void) {
 
     unsigned char buf[CONTROL_MSG_MAX_SIZE];
     size_t size = control_msg_serialize(&msg, buf);
-    assert(size == 19);
+    assert(size == 27);
 
     const unsigned char expected[] = {
         CONTROL_MSG_TYPE_SET_CLIPBOARD,
+        0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, // sequence
         1, // paste
         0x00, 0x00, 0x00, 0x0d, // text length
         'h', 'e', 'l', 'l', 'o', ',', ' ', 'w', 'o', 'r', 'l', 'd', '!', // text

app/tests/test_device_msg_deserialize.c

@@ -47,11 +47,26 @@ static void test_deserialize_clipboard_big(void) {
     device_msg_destroy(&msg);
 }
 
+static void test_deserialize_ack_set_clipboard(void) {
+    const unsigned char input[] = {
+        DEVICE_MSG_TYPE_ACK_CLIPBOARD,
+        0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, // sequence
+    };
+
+    struct device_msg msg;
+    ssize_t r = device_msg_deserialize(input, sizeof(input), &msg);
+    assert(r == 9);
+
+    assert(msg.type == DEVICE_MSG_TYPE_ACK_CLIPBOARD);
+    assert(msg.ack_clipboard.sequence == UINT64_C(0x0102030405060708));
+}
+
 int main(int argc, char *argv[]) {
     (void) argc;
     (void) argv;
 
     test_deserialize_clipboard();
     test_deserialize_clipboard_big();
+    test_deserialize_ack_set_clipboard();
     return 0;
 }

server/src/main/java/com/genymobile/scrcpy/ControlMessage.java

@@ -18,6 +18,8 @@ public final class ControlMessage {
     public static final int TYPE_SET_SCREEN_POWER_MODE = 10;
     public static final int TYPE_ROTATE_DEVICE = 11;
 
+    public static final long SEQUENCE_INVALID = 0;
+
     private int type;
     private String text;
     private int metaState; // KeyEvent.META_*
@@ -31,6 +33,7 @@ public final class ControlMessage {
     private int vScroll;
     private boolean paste;
     private int repeat;
+    private long sequence;
 
     private ControlMessage() {
     }
@@ -79,9 +82,10 @@ public final class ControlMessage {
         return msg;
     }
 
-    public static ControlMessage createSetClipboard(String text, boolean paste) {
+    public static ControlMessage createSetClipboard(long sequence, String text, boolean paste) {
         ControlMessage msg = new ControlMessage();
         msg.type = TYPE_SET_CLIPBOARD;
+        msg.sequence = sequence;
         msg.text = text;
         msg.paste = paste;
         return msg;
@@ -154,4 +158,8 @@ public final class ControlMessage {
     public int getRepeat() {
         return repeat;
     }
+
+    public long getSequence() {
+        return sequence;
+    }
 }

server/src/main/java/com/genymobile/scrcpy/ControlMessageReader.java

@@ -13,11 +13,11 @@ public class ControlMessageReader {
     static final int INJECT_SCROLL_EVENT_PAYLOAD_LENGTH = 20;
     static final int BACK_OR_SCREEN_ON_LENGTH = 1;
     static final int SET_SCREEN_POWER_MODE_PAYLOAD_LENGTH = 1;
-    static final int SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH = 1;
+    static final int SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH = 9;
 
     private static final int MESSAGE_MAX_SIZE = 1 << 18; // 256k
 
-    public static final int CLIPBOARD_TEXT_MAX_LENGTH = MESSAGE_MAX_SIZE - 6; // type: 1 byte; paste flag: 1 byte; length: 4 bytes
+    public static final int CLIPBOARD_TEXT_MAX_LENGTH = MESSAGE_MAX_SIZE - 14; // type: 1 byte; sequence: 8 bytes; paste flag: 1 byte; length: 4 bytes
     public static final int INJECT_TEXT_MAX_LENGTH = 300;
 
     private final byte[] rawBuffer = new byte[MESSAGE_MAX_SIZE];
@@ -166,12 +166,13 @@ public class ControlMessageReader {
         if (buffer.remaining() < SET_CLIPBOARD_FIXED_PAYLOAD_LENGTH) {
             return null;
         }
+        long sequence = buffer.getLong();
         boolean paste = buffer.get() != 0;
         String text = parseString();
         if (text == null) {
             return null;
         }
-        return ControlMessage.createSetClipboard(text, paste);
+        return ControlMessage.createSetClipboard(sequence, text, paste);
     }
 
     private ControlMessage parseSetScreenPowerMode() {

server/src/main/java/com/genymobile/scrcpy/Controller.java

@@ -120,7 +120,12 @@ public class Controller {
                 }
                 break;
             case ControlMessage.TYPE_SET_CLIPBOARD:
+                long sequence = msg.getSequence();
                 setClipboard(msg.getText(), msg.getPaste());
+                if (sequence != ControlMessage.SEQUENCE_INVALID) {
+                    // Acknowledgement requested
+                    sender.pushAckClipboard(sequence);
+                }
                 break;
             case ControlMessage.TYPE_SET_SCREEN_POWER_MODE:
                 if (device.supportsInputEvents()) {

server/src/main/java/com/genymobile/scrcpy/DeviceMessage.java

@@ -3,9 +3,13 @@ package com.genymobile.scrcpy;
 public final class DeviceMessage {
 
     public static final int TYPE_CLIPBOARD = 0;
+    public static final int TYPE_ACK_CLIPBOARD = 1;
+
+    public static final long SEQUENCE_INVALID = ControlMessage.SEQUENCE_INVALID;
 
     private int type;
     private String text;
+    private long sequence;
 
     private DeviceMessage() {
     }
@@ -17,6 +21,13 @@ public final class DeviceMessage {
         return event;
     }
 
+    public static DeviceMessage createAckClipboard(long sequence) {
+        DeviceMessage event = new DeviceMessage();
+        event.type = TYPE_ACK_CLIPBOARD;
+        event.sequence = sequence;
+        return event;
+    }
+
     public int getType() {
         return type;
     }
@@ -24,4 +35,8 @@ public final class DeviceMessage {
     public String getText() {
         return text;
     }
+
+    public long getSequence() {
+        return sequence;
+    }
 }

server/src/main/java/com/genymobile/scrcpy/DeviceMessageSender.java

@@ -8,6 +8,8 @@ public final class DeviceMessageSender {
 
     private String clipboardText;
 
+    private long ack;
+
     public DeviceMessageSender(DesktopConnection connection) {
         this.connection = connection;
     }
@@ -17,18 +19,34 @@ public final class DeviceMessageSender {
         notify();
     }
 
+    public synchronized void pushAckClipboard(long sequence) {
+        ack = sequence;
+        notify();
+    }
+
     public void loop() throws IOException, InterruptedException {
         while (true) {
             String text;
+            long sequence;
             synchronized (this) {
-                while (clipboardText == null) {
+                while (ack == DeviceMessage.SEQUENCE_INVALID && clipboardText == null) {
                     wait();
                 }
                 text = clipboardText;
                 clipboardText = null;
+
+                sequence = ack;
+                ack = DeviceMessage.SEQUENCE_INVALID;
             }
+
+            if (sequence != DeviceMessage.SEQUENCE_INVALID) {
+                DeviceMessage event = DeviceMessage.createAckClipboard(sequence);
+                connection.sendDeviceMessage(event);
+            }
+            if (text != null) {
                 DeviceMessage event = DeviceMessage.createClipboard(text);
                 connection.sendDeviceMessage(event);
             }
         }
     }
+}

server/src/main/java/com/genymobile/scrcpy/DeviceMessageWriter.java

@@ -15,7 +15,7 @@ public class DeviceMessageWriter {
 
     public void writeTo(DeviceMessage msg, OutputStream output) throws IOException {
         buffer.clear();
-        buffer.put((byte) DeviceMessage.TYPE_CLIPBOARD);
+        buffer.put((byte) msg.getType());
         switch (msg.getType()) {
             case DeviceMessage.TYPE_CLIPBOARD:
                 String text = msg.getText();
@@ -25,6 +25,10 @@ public class DeviceMessageWriter {
                 buffer.put(raw, 0, len);
                 output.write(rawBuffer, 0, buffer.position());
                 break;
+            case DeviceMessage.TYPE_ACK_CLIPBOARD:
+                buffer.putLong(msg.getSequence());
+                output.write(rawBuffer, 0, buffer.position());
+                break;
             default:
                 Ln.w("Unknown device message: " + msg.getType());
                 break;

server/src/test/java/com/genymobile/scrcpy/ControlMessageReaderTest.java

@@ -235,6 +235,7 @@ public class ControlMessageReaderTest {
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         DataOutputStream dos = new DataOutputStream(bos);
         dos.writeByte(ControlMessage.TYPE_SET_CLIPBOARD);
+        dos.writeLong(0x0102030405060708L); // sequence
         dos.writeByte(1); // paste
         byte[] text = "testé".getBytes(StandardCharsets.UTF_8);
         dos.writeInt(text.length);
@@ -246,6 +247,7 @@ public class ControlMessageReaderTest {
         ControlMessage event = reader.next();
 
         Assert.assertEquals(ControlMessage.TYPE_SET_CLIPBOARD, event.getType());
+        Assert.assertEquals(0x0102030405060708L, event.getSequence());
         Assert.assertEquals("testé", event.getText());
         Assert.assertTrue(event.getPaste());
     }
@@ -259,6 +261,7 @@ public class ControlMessageReaderTest {
         dos.writeByte(ControlMessage.TYPE_SET_CLIPBOARD);
 
         byte[] rawText = new byte[ControlMessageReader.CLIPBOARD_TEXT_MAX_LENGTH];
+        dos.writeLong(0x0807060504030201L); // sequence
         dos.writeByte(1); // paste
         Arrays.fill(rawText, (byte) 'a');
         String text = new String(rawText, 0, rawText.length);
@@ -272,6 +275,7 @@ public class ControlMessageReaderTest {
         ControlMessage event = reader.next();
 
         Assert.assertEquals(ControlMessage.TYPE_SET_CLIPBOARD, event.getType());
+        Assert.assertEquals(0x0807060504030201L, event.getSequence());
         Assert.assertEquals(text, event.getText());
         Assert.assertTrue(event.getPaste());
     }

server/src/test/java/com/genymobile/scrcpy/DeviceMessageWriterTest.java

@@ -32,4 +32,24 @@ public class DeviceMessageWriterTest {
 
         Assert.assertArrayEquals(expected, actual);
     }
+
+    @Test
+    public void testSerializeAckSetClipboard() throws IOException {
+        DeviceMessageWriter writer = new DeviceMessageWriter();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(DeviceMessage.TYPE_ACK_CLIPBOARD);
+        dos.writeLong(0x0102030405060708L);
+
+        byte[] expected = bos.toByteArray();
+
+        DeviceMessage msg = DeviceMessage.createAckClipboard(0x0102030405060708L);
+        bos = new ByteArrayOutputStream();
+        writer.writeTo(msg, bos);
+
+        byte[] actual = bos.toByteArray();
+
+        Assert.assertArrayEquals(expected, actual);
+    }
 }