scrcpy/app/src/aoa_hid.c

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#include "util/log.h"
#include <assert.h>
#include <stdio.h>
#include "aoa_hid.h"
// See <https://source.android.com/devices/accessories/aoa2#hid-support>.
#define ACCESSORY_REGISTER_HID 54
#define ACCESSORY_SET_HID_REPORT_DESC 56
#define ACCESSORY_SEND_HID_EVENT 57
#define ACCESSORY_UNREGISTER_HID 55
#define DEFAULT_TIMEOUT 1000
static void
sc_hid_event_log(const struct sc_hid_event *event) {
// HID Event: [00] FF FF FF FF...
assert(event->size);
unsigned buffer_size = event->size * 3 + 1;
char *buffer = malloc(buffer_size);
if (!buffer) {
return;
}
for (unsigned i = 0; i < event->size; ++i) {
snprintf(buffer + i * 3, 4, " %02x", event->buffer[i]);
}
LOGV("HID Event: [%d]%s", event->accessory_id, buffer);
free(buffer);
}
void
sc_hid_event_init(struct sc_hid_event *hid_event, uint16_t accessory_id,
unsigned char *buffer, uint16_t buffer_size) {
hid_event->accessory_id = accessory_id;
hid_event->buffer = buffer;
hid_event->size = buffer_size;
hid_event->delay = 0;
}
void
sc_hid_event_destroy(struct sc_hid_event *hid_event) {
free(hid_event->buffer);
}
static inline void
log_libusb_error(enum libusb_error errcode) {
LOGW("libusb error: %s", libusb_strerror(errcode));
}
static bool
accept_device(libusb_device *device, const char *serial) {
// do not log any USB error in this function, it is expected that many USB
// devices available on the computer have permission restrictions
struct libusb_device_descriptor desc;
libusb_get_device_descriptor(device, &desc);
if (!desc.iSerialNumber) {
return false;
}
libusb_device_handle *handle;
int result = libusb_open(device, &handle);
if (result < 0) {
return false;
}
char buffer[128];
result = libusb_get_string_descriptor_ascii(handle, desc.iSerialNumber,
(unsigned char *) buffer,
sizeof(buffer));
libusb_close(handle);
if (result < 0) {
return false;
}
buffer[sizeof(buffer) - 1] = '\0'; // just in case
// accept the device if its serial matches
return !strcmp(buffer, serial);
}
static libusb_device *
sc_aoa_find_usb_device(const char *serial) {
if (!serial) {
return NULL;
}
libusb_device **list;
libusb_device *result = NULL;
ssize_t count = libusb_get_device_list(NULL, &list);
if (count < 0) {
log_libusb_error((enum libusb_error) count);
return NULL;
}
for (size_t i = 0; i < (size_t) count; ++i) {
libusb_device *device = list[i];
if (accept_device(device, serial)) {
result = libusb_ref_device(device);
break;
}
}
libusb_free_device_list(list, 1);
return result;
}
static int
sc_aoa_open_usb_handle(libusb_device *device, libusb_device_handle **handle) {
int result = libusb_open(device, handle);
if (result < 0) {
log_libusb_error((enum libusb_error) result);
return result;
}
return 0;
}
bool
sc_aoa_init(struct sc_aoa *aoa, const char *serial) {
cbuf_init(&aoa->queue);
if (!sc_mutex_init(&aoa->mutex)) {
return false;
}
if (!sc_cond_init(&aoa->event_cond)) {
sc_mutex_destroy(&aoa->mutex);
return false;
}
if (libusb_init(&aoa->usb_context) != LIBUSB_SUCCESS) {
sc_cond_destroy(&aoa->event_cond);
sc_mutex_destroy(&aoa->mutex);
return false;
}
aoa->usb_device = sc_aoa_find_usb_device(serial);
if (!aoa->usb_device) {
LOGW("USB device of serial %s not found", serial);
libusb_exit(aoa->usb_context);
sc_mutex_destroy(&aoa->mutex);
sc_cond_destroy(&aoa->event_cond);
return false;
}
if (sc_aoa_open_usb_handle(aoa->usb_device, &aoa->usb_handle) < 0) {
LOGW("Open USB handle failed");
libusb_unref_device(aoa->usb_device);
libusb_exit(aoa->usb_context);
sc_cond_destroy(&aoa->event_cond);
sc_mutex_destroy(&aoa->mutex);
return false;
}
aoa->stopped = false;
return true;
}
void
sc_aoa_destroy(struct sc_aoa *aoa) {
// Destroy remaining events
struct sc_hid_event event;
while (cbuf_take(&aoa->queue, &event)) {
sc_hid_event_destroy(&event);
}
libusb_close(aoa->usb_handle);
libusb_unref_device(aoa->usb_device);
libusb_exit(aoa->usb_context);
sc_cond_destroy(&aoa->event_cond);
sc_mutex_destroy(&aoa->mutex);
}
static bool
sc_aoa_register_hid(struct sc_aoa *aoa, uint16_t accessory_id,
uint16_t report_desc_size) {
uint8_t request_type = LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR;
uint8_t request = ACCESSORY_REGISTER_HID;
// <https://source.android.com/devices/accessories/aoa2.html#hid-support>
// value (arg0): accessory assigned ID for the HID device
// index (arg1): total length of the HID report descriptor
uint16_t value = accessory_id;
uint16_t index = report_desc_size;
unsigned char *buffer = NULL;
uint16_t length = 0;
int result = libusb_control_transfer(aoa->usb_handle, request_type, request,
value, index, buffer, length,
DEFAULT_TIMEOUT);
if (result < 0) {
log_libusb_error((enum libusb_error) result);
return false;
}
return true;
}
static bool
sc_aoa_set_hid_report_desc(struct sc_aoa *aoa, uint16_t accessory_id,
const unsigned char *report_desc,
uint16_t report_desc_size) {
uint8_t request_type = LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR;
uint8_t request = ACCESSORY_SET_HID_REPORT_DESC;
/**
* If the HID descriptor is longer than the endpoint zero max packet size,
* the descriptor will be sent in multiple ACCESSORY_SET_HID_REPORT_DESC
* commands. The data for the descriptor must be sent sequentially
* if multiple packets are needed.
* <https://source.android.com/devices/accessories/aoa2.html#hid-support>
*
* libusb handles packet abstraction internally, so we don't need to care
* about bMaxPacketSize0 here.
*
* See <https://libusb.sourceforge.io/api-1.0/libusb_packetoverflow.html>
*/
// value (arg0): accessory assigned ID for the HID device
// index (arg1): offset of data (buffer) in descriptor
uint16_t value = accessory_id;
uint16_t index = 0;
// libusb_control_transfer expects a pointer to non-const
unsigned char *buffer = (unsigned char *) report_desc;
uint16_t length = report_desc_size;
int result = libusb_control_transfer(aoa->usb_handle, request_type, request,
value, index, buffer, length,
DEFAULT_TIMEOUT);
if (result < 0) {
log_libusb_error((enum libusb_error) result);
return false;
}
return true;
}
bool
sc_aoa_setup_hid(struct sc_aoa *aoa, uint16_t accessory_id,
const unsigned char *report_desc, uint16_t report_desc_size) {
bool ok = sc_aoa_register_hid(aoa, accessory_id, report_desc_size);
if (!ok) {
return false;
}
ok = sc_aoa_set_hid_report_desc(aoa, accessory_id, report_desc,
report_desc_size);
if (!ok) {
if (!sc_aoa_unregister_hid(aoa, accessory_id)) {
LOGW("Could not unregister HID");
}
return false;
}
return true;
}
static bool
sc_aoa_send_hid_event(struct sc_aoa *aoa, const struct sc_hid_event *event) {
uint8_t request_type = LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR;
uint8_t request = ACCESSORY_SEND_HID_EVENT;
// <https://source.android.com/devices/accessories/aoa2.html#hid-support>
// value (arg0): accessory assigned ID for the HID device
// index (arg1): 0 (unused)
uint16_t value = event->accessory_id;
uint16_t index = 0;
unsigned char *buffer = event->buffer;
uint16_t length = event->size;
int result = libusb_control_transfer(aoa->usb_handle, request_type, request,
value, index, buffer, length,
DEFAULT_TIMEOUT);
if (result < 0) {
log_libusb_error((enum libusb_error) result);
return false;
}
return true;
}
bool
sc_aoa_unregister_hid(struct sc_aoa *aoa, const uint16_t accessory_id) {
uint8_t request_type = LIBUSB_ENDPOINT_OUT | LIBUSB_REQUEST_TYPE_VENDOR;
uint8_t request = ACCESSORY_UNREGISTER_HID;
// <https://source.android.com/devices/accessories/aoa2.html#hid-support>
// value (arg0): accessory assigned ID for the HID device
// index (arg1): 0
uint16_t value = accessory_id;
uint16_t index = 0;
unsigned char *buffer = NULL;
uint16_t length = 0;
int result = libusb_control_transfer(aoa->usb_handle, request_type, request,
value, index, buffer, length,
DEFAULT_TIMEOUT);
if (result < 0) {
log_libusb_error((enum libusb_error) result);
return false;
}
return true;
}
bool
sc_aoa_push_hid_event(struct sc_aoa *aoa, const struct sc_hid_event *event) {
if (sc_get_log_level() <= SC_LOG_LEVEL_VERBOSE) {
sc_hid_event_log(event);
}
sc_mutex_lock(&aoa->mutex);
bool was_empty = cbuf_is_empty(&aoa->queue);
bool res = cbuf_push(&aoa->queue, *event);
if (was_empty) {
sc_cond_signal(&aoa->event_cond);
}
sc_mutex_unlock(&aoa->mutex);
return res;
}
static int
run_aoa_thread(void *data) {
struct sc_aoa *aoa = data;
for (;;) {
sc_mutex_lock(&aoa->mutex);
while (!aoa->stopped && cbuf_is_empty(&aoa->queue)) {
sc_cond_wait(&aoa->event_cond, &aoa->mutex);
}
if (aoa->stopped) {
// Stop immediately, do not process further events
sc_mutex_unlock(&aoa->mutex);
break;
}
struct sc_hid_event event;
bool non_empty = cbuf_take(&aoa->queue, &event);
assert(non_empty);
(void) non_empty;
assert(event.delay >= 0);
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);
break;
}
}
sc_mutex_unlock(&aoa->mutex);
bool ok = sc_aoa_send_hid_event(aoa, &event);
sc_hid_event_destroy(&event);
if (!ok) {
LOGW("Could not send HID event to USB device");
}
}
return 0;
}
bool
sc_aoa_start(struct sc_aoa *aoa) {
LOGD("Starting AOA thread");
bool ok = sc_thread_create(&aoa->thread, run_aoa_thread, "aoa_thread", aoa);
if (!ok) {
LOGC("Could not start AOA thread");
return false;
}
return true;
}
void
sc_aoa_stop(struct sc_aoa *aoa) {
sc_mutex_lock(&aoa->mutex);
aoa->stopped = true;
sc_cond_signal(&aoa->event_cond);
sc_mutex_unlock(&aoa->mutex);
}
void
sc_aoa_join(struct sc_aoa *aoa) {
sc_thread_join(&aoa->thread, NULL);
}