tap-win32.c

   1 /*
   2  *  TAP-Win32 -- A kernel driver to provide virtual tap device functionality
   3  *               on Windows.  Originally derived from the CIPE-Win32
   4  *               project by Damion K. Wilson, with extensive modifications by
   5  *               James Yonan.
   6  *
   7  *  All source code which derives from the CIPE-Win32 project is
   8  *  Copyright (C) Damion K. Wilson, 2003, and is released under the
   9  *  GPL version 2 (see below).
  10  *
  11  *  All other source code is Copyright (C) James Yonan, 2003-2004,
  12  *  and is released under the GPL version 2 (see below).
  13  *
  14  *  This program is free software; you can redistribute it and/or modify
  15  *  it under the terms of the GNU General Public License as published by
  16  *  the Free Software Foundation; either version 2 of the License, or
  17  *  (at your option) any later version.
  18  *
  19  *  This program is distributed in the hope that it will be useful,
  20  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  *  GNU General Public License for more details.
  23  *
  24  *  You should have received a copy of the GNU General Public License
  25  *  along with this program (see the file COPYING included with this
  26  *  distribution); if not, see <http://www.gnu.org/licenses/>.
  27  */
  28 #include "qemu-common.h"
  29 #include "net.h"
  30 #include "sysemu.h"
  31 #include <stdio.h>
  32 #include <windows.h>
  33 #include <winioctl.h>
  34
  35 //=============
  36 // TAP IOCTLs
  37 //=============
  38
  39 #define TAP_CONTROL_CODE(request,method) \
  40   CTL_CODE (FILE_DEVICE_UNKNOWN, request, method, FILE_ANY_ACCESS)
  41
  42 #define TAP_IOCTL_GET_MAC               TAP_CONTROL_CODE (1, METHOD_BUFFERED)
  43 #define TAP_IOCTL_GET_VERSION           TAP_CONTROL_CODE (2, METHOD_BUFFERED)
  44 #define TAP_IOCTL_GET_MTU               TAP_CONTROL_CODE (3, METHOD_BUFFERED)
  45 #define TAP_IOCTL_GET_INFO              TAP_CONTROL_CODE (4, METHOD_BUFFERED)
  46 #define TAP_IOCTL_CONFIG_POINT_TO_POINT TAP_CONTROL_CODE (5, METHOD_BUFFERED)
  47 #define TAP_IOCTL_SET_MEDIA_STATUS      TAP_CONTROL_CODE (6, METHOD_BUFFERED)
  48 #define TAP_IOCTL_CONFIG_DHCP_MASQ      TAP_CONTROL_CODE (7, METHOD_BUFFERED)
  49 #define TAP_IOCTL_GET_LOG_LINE          TAP_CONTROL_CODE (8, METHOD_BUFFERED)
  50 #define TAP_IOCTL_CONFIG_DHCP_SET_OPT   TAP_CONTROL_CODE (9, METHOD_BUFFERED)
  51
  52 //=================
  53 // Registry keys
  54 //=================
  55
  56 #define ADAPTER_KEY "SYSTEM\\CurrentControlSet\\Control\\Class\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
  57
  58 #define NETWORK_CONNECTIONS_KEY "SYSTEM\\CurrentControlSet\\Control\\Network\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
  59
  60 //======================
  61 // Filesystem prefixes
  62 //======================
  63
  64 #define USERMODEDEVICEDIR "\\\\.\\Global\\"
  65 #define TAPSUFFIX         ".tap"
  66
  67
  68 //======================
  69 // Compile time configuration
  70 //======================
  71
  72 //#define DEBUG_TAP_WIN32
  73
  74 #define TUN_ASYNCHRONOUS_WRITES 1
  75
  76 #define TUN_BUFFER_SIZE 1560
  77 #define TUN_MAX_BUFFER_COUNT 32
  78
  79 /*
  80  * The data member "buffer" must be the first element in the tun_buffer
  81  * structure. See the function, tap_win32_free_buffer.
  82  */
  83 typedef struct tun_buffer_s {
  84     unsigned char buffer [TUN_BUFFER_SIZE];
  85     unsigned long read_size;
  86     struct tun_buffer_s* next;
  87 } tun_buffer_t;
  88
  89 typedef struct tap_win32_overlapped {
  90     HANDLE handle;
  91     HANDLE read_event;
  92     HANDLE write_event;
  93     HANDLE output_queue_semaphore;
  94     HANDLE free_list_semaphore;
  95     HANDLE tap_semaphore;
  96     CRITICAL_SECTION output_queue_cs;
  97     CRITICAL_SECTION free_list_cs;
  98     OVERLAPPED read_overlapped;
  99     OVERLAPPED write_overlapped;
 100     tun_buffer_t buffers[TUN_MAX_BUFFER_COUNT];
 101     tun_buffer_t* free_list;
 102     tun_buffer_t* output_queue_front;
 103     tun_buffer_t* output_queue_back;
 104 } tap_win32_overlapped_t;
 105
 106 static tap_win32_overlapped_t tap_overlapped;
 107
 108 static tun_buffer_t* get_buffer_from_free_list(tap_win32_overlapped_t* const overlapped)
 109 {
 110     tun_buffer_t* buffer = NULL;
 111     WaitForSingleObject(overlapped->free_list_semaphore, INFINITE);
 112     EnterCriticalSection(&overlapped->free_list_cs);
 113     buffer = overlapped->free_list;
 114 //    assert(buffer != NULL);
 115     overlapped->free_list = buffer->next;
 116     LeaveCriticalSection(&overlapped->free_list_cs);
 117     buffer->next = NULL;
 118     return buffer;
 119 }
 120
 121 static void put_buffer_on_free_list(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
 122 {
 123     EnterCriticalSection(&overlapped->free_list_cs);
 124     buffer->next = overlapped->free_list;
 125     overlapped->free_list = buffer;
 126     LeaveCriticalSection(&overlapped->free_list_cs);
 127     ReleaseSemaphore(overlapped->free_list_semaphore, 1, NULL);
 128 }
 129
 130 static tun_buffer_t* get_buffer_from_output_queue(tap_win32_overlapped_t* const overlapped, const int block)
 131 {
 132     tun_buffer_t* buffer = NULL;
 133     DWORD result, timeout = block ? INFINITE : 0L;
 134
 135     // Non-blocking call
 136     result = WaitForSingleObject(overlapped->output_queue_semaphore, timeout);
 137
 138     switch (result)
 139     {
 140         // The semaphore object was signaled.
 141         case WAIT_OBJECT_0:
 142             EnterCriticalSection(&overlapped->output_queue_cs);
 143
 144             buffer = overlapped->output_queue_front;
 145             overlapped->output_queue_front = buffer->next;
 146
 147             if(overlapped->output_queue_front == NULL) {
 148                 overlapped->output_queue_back = NULL;
 149             }
 150
 151             LeaveCriticalSection(&overlapped->output_queue_cs);
 152             break;
 153
 154         // Semaphore was nonsignaled, so a time-out occurred.
 155         case WAIT_TIMEOUT:
 156             // Cannot open another window.
 157             break;
 158     }
 159
 160     return buffer;
 161 }
 162
 163 static tun_buffer_t* get_buffer_from_output_queue_immediate (tap_win32_overlapped_t* const overlapped)
 164 {
 165     return get_buffer_from_output_queue(overlapped, 0);
 166 }
 167
 168 static void put_buffer_on_output_queue(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
 169 {
 170     EnterCriticalSection(&overlapped->output_queue_cs);
 171
 172     if(overlapped->output_queue_front == NULL && overlapped->output_queue_back == NULL) {
 173         overlapped->output_queue_front = overlapped->output_queue_back = buffer;
 174     } else {
 175         buffer->next = NULL;
 176         overlapped->output_queue_back->next = buffer;
 177         overlapped->output_queue_back = buffer;
 178     }
 179
 180     LeaveCriticalSection(&overlapped->output_queue_cs);
 181
 182     ReleaseSemaphore(overlapped->output_queue_semaphore, 1, NULL);
 183 }
 184
 185
 186 static int is_tap_win32_dev(const char *guid)
 187 {
 188     HKEY netcard_key;
 189     LONG status;
 190     DWORD len;
 191     int i = 0;
 192
 193     status = RegOpenKeyEx(
 194         HKEY_LOCAL_MACHINE,
 195         ADAPTER_KEY,
 196         0,
 197         KEY_READ,
 198         &netcard_key);
 199
 200     if (status != ERROR_SUCCESS) {
 201         return FALSE;
 202     }
 203
 204     for (;;) {
 205         char enum_name[256];
 206         char unit_string[256];
 207         HKEY unit_key;
 208         char component_id_string[] = "ComponentId";
 209         char component_id[256];
 210         char net_cfg_instance_id_string[] = "NetCfgInstanceId";
 211         char net_cfg_instance_id[256];
 212         DWORD data_type;
 213
 214         len = sizeof (enum_name);
 215         status = RegEnumKeyEx(
 216             netcard_key,
 217             i,
 218             enum_name,
 219             &len,
 220             NULL,
 221             NULL,
 222             NULL,
 223             NULL);
 224
 225         if (status == ERROR_NO_MORE_ITEMS)
 226             break;
 227         else if (status != ERROR_SUCCESS) {
 228             return FALSE;
 229         }
 230
 231         snprintf (unit_string, sizeof(unit_string), "%s\\%s",
 232                   ADAPTER_KEY, enum_name);
 233
 234         status = RegOpenKeyEx(
 235             HKEY_LOCAL_MACHINE,
 236             unit_string,
 237             0,
 238             KEY_READ,
 239             &unit_key);
 240
 241         if (status != ERROR_SUCCESS) {
 242             return FALSE;
 243         } else {
 244             len = sizeof (component_id);
 245             status = RegQueryValueEx(
 246                 unit_key,
 247                 component_id_string,
 248                 NULL,
 249                 &data_type,
 250                 (LPBYTE)component_id,
 251                 &len);
 252
 253             if (!(status != ERROR_SUCCESS || data_type != REG_SZ)) {
 254                 len = sizeof (net_cfg_instance_id);
 255                 status = RegQueryValueEx(
 256                     unit_key,
 257                     net_cfg_instance_id_string,
 258                     NULL,
 259                     &data_type,
 260                     (LPBYTE)net_cfg_instance_id,
 261                     &len);
 262
 263                 if (status == ERROR_SUCCESS && data_type == REG_SZ) {
 264                     if (/* !strcmp (component_id, TAP_COMPONENT_ID) &&*/
 265                         !strcmp (net_cfg_instance_id, guid)) {
 266                         RegCloseKey (unit_key);
 267                         RegCloseKey (netcard_key);
 268                         return TRUE;
 269                     }
 270                 }
 271             }
 272             RegCloseKey (unit_key);
 273         }
 274         ++i;
 275     }
 276
 277     RegCloseKey (netcard_key);
 278     return FALSE;
 279 }
 280
 281 static int get_device_guid(
 282     char *name,
 283     int name_size,
 284     char *actual_name,
 285     int actual_name_size)
 286 {
 287     LONG status;
 288     HKEY control_net_key;
 289     DWORD len;
 290     int i = 0;
 291     int stop = 0;
 292
 293     status = RegOpenKeyEx(
 294         HKEY_LOCAL_MACHINE,
 295         NETWORK_CONNECTIONS_KEY,
 296         0,
 297         KEY_READ,
 298         &control_net_key);
 299
 300     if (status != ERROR_SUCCESS) {
 301         return -1;
 302     }
 303
 304     while (!stop)
 305     {
 306         char enum_name[256];
 307         char connection_string[256];
 308         HKEY connection_key;
 309         char name_data[256];
 310         DWORD name_type;
 311         const char name_string[] = "Name";
 312
 313         len = sizeof (enum_name);
 314         status = RegEnumKeyEx(
 315             control_net_key,
 316             i,
 317             enum_name,
 318             &len,
 319             NULL,
 320             NULL,
 321             NULL,
 322             NULL);
 323
 324         if (status == ERROR_NO_MORE_ITEMS)
 325             break;
 326         else if (status != ERROR_SUCCESS) {
 327             return -1;
 328         }
 329
 330         snprintf(connection_string,
 331              sizeof(connection_string),
 332              "%s\\%s\\Connection",
 333              NETWORK_CONNECTIONS_KEY, enum_name);
 334
 335         status = RegOpenKeyEx(
 336             HKEY_LOCAL_MACHINE,
 337             connection_string,
 338             0,
 339             KEY_READ,
 340             &connection_key);
 341
 342         if (status == ERROR_SUCCESS) {
 343             len = sizeof (name_data);
 344             status = RegQueryValueEx(
 345                 connection_key,
 346                 name_string,
 347                 NULL,
 348                 &name_type,
 349                 (LPBYTE)name_data,
 350                 &len);
 351
 352             if (status != ERROR_SUCCESS || name_type != REG_SZ) {
 353                     return -1;
 354             }
 355             else {
 356                 if (is_tap_win32_dev(enum_name)) {
 357                     snprintf(name, name_size, "%s", enum_name);
 358                     if (actual_name) {
 359                         if (strcmp(actual_name, "") != 0) {
 360                             if (strcmp(name_data, actual_name) != 0) {
 361                                 RegCloseKey (connection_key);
 362                                 ++i;
 363                                 continue;
 364                             }
 365                         }
 366                         else {
 367                             snprintf(actual_name, actual_name_size, "%s", name_data);
 368                         }
 369                     }
 370                     stop = 1;
 371                 }
 372             }
 373
 374             RegCloseKey (connection_key);
 375         }
 376         ++i;
 377     }
 378
 379     RegCloseKey (control_net_key);
 380
 381     if (stop == 0)
 382         return -1;
 383
 384     return 0;
 385 }
 386
 387 static int tap_win32_set_status(HANDLE handle, int status)
 388 {
 389     unsigned long len = 0;
 390
 391     return DeviceIoControl(handle, TAP_IOCTL_SET_MEDIA_STATUS,
 392                 &status, sizeof (status),
 393                 &status, sizeof (status), &len, NULL);
 394 }
 395
 396 static void tap_win32_overlapped_init(tap_win32_overlapped_t* const overlapped, const HANDLE handle)
 397 {
 398     overlapped->handle = handle;
 399
 400     overlapped->read_event = CreateEvent(NULL, FALSE, FALSE, NULL);
 401     overlapped->write_event = CreateEvent(NULL, FALSE, FALSE, NULL);
 402
 403     overlapped->read_overlapped.Offset = 0;
 404     overlapped->read_overlapped.OffsetHigh = 0;
 405     overlapped->read_overlapped.hEvent = overlapped->read_event;
 406
 407     overlapped->write_overlapped.Offset = 0;
 408     overlapped->write_overlapped.OffsetHigh = 0;
 409     overlapped->write_overlapped.hEvent = overlapped->write_event;
 410
 411     InitializeCriticalSection(&overlapped->output_queue_cs);
 412     InitializeCriticalSection(&overlapped->free_list_cs);
 413
 414     overlapped->output_queue_semaphore = CreateSemaphore(
 415         NULL,   // default security attributes
 416         0,   // initial count
 417         TUN_MAX_BUFFER_COUNT,   // maximum count
 418         NULL);  // unnamed semaphore
 419
 420     if(!overlapped->output_queue_semaphore)  {
 421         fprintf(stderr, "error creating output queue semaphore!\n");
 422     }
 423
 424     overlapped->free_list_semaphore = CreateSemaphore(
 425         NULL,   // default security attributes
 426         TUN_MAX_BUFFER_COUNT,   // initial count
 427         TUN_MAX_BUFFER_COUNT,   // maximum count
 428         NULL);  // unnamed semaphore
 429
 430     if(!overlapped->free_list_semaphore)  {
 431         fprintf(stderr, "error creating free list semaphore!\n");
 432     }
 433
 434     overlapped->free_list = overlapped->output_queue_front = overlapped->output_queue_back = NULL;
 435
 436     {
 437         unsigned index;
 438         for(index = 0; index < TUN_MAX_BUFFER_COUNT; index++) {
 439             tun_buffer_t* element = &overlapped->buffers[index];
 440             element->next = overlapped->free_list;
 441             overlapped->free_list = element;
 442         }
 443     }
 444     /* To count buffers, initially no-signal. */
 445     overlapped->tap_semaphore = CreateSemaphore(NULL, 0, TUN_MAX_BUFFER_COUNT, NULL);
 446     if(!overlapped->tap_semaphore)
 447         fprintf(stderr, "error creating tap_semaphore.\n");
 448 }
 449
 450 static int tap_win32_write(tap_win32_overlapped_t *overlapped,
 451                            const void *buffer, unsigned long size)
 452 {
 453     unsigned long write_size;
 454     BOOL result;
 455     DWORD error;
 456
 457     result = GetOverlappedResult( overlapped->handle, &overlapped->write_overlapped,
 458                                   &write_size, FALSE);
 459
 460     if (!result && GetLastError() == ERROR_IO_INCOMPLETE)
 461         WaitForSingleObject(overlapped->write_event, INFINITE);
 462
 463     result = WriteFile(overlapped->handle, buffer, size,
 464                        &write_size, &overlapped->write_overlapped);
 465
 466     if (!result) {
 467         switch (error = GetLastError())
 468         {
 469         case ERROR_IO_PENDING:
 470 #ifndef TUN_ASYNCHRONOUS_WRITES
 471             WaitForSingleObject(overlapped->write_event, INFINITE);
 472 #endif
 473             break;
 474         default:
 475             return -1;
 476         }
 477     }
 478
 479     return 0;
 480 }
 481
 482 static DWORD WINAPI tap_win32_thread_entry(LPVOID param)
 483 {
 484     tap_win32_overlapped_t *overlapped = (tap_win32_overlapped_t*)param;
 485     unsigned long read_size;
 486     BOOL result;
 487     DWORD dwError;
 488     tun_buffer_t* buffer = get_buffer_from_free_list(overlapped);
 489
 490
 491     for (;;) {
 492         result = ReadFile(overlapped->handle,
 493                           buffer->buffer,
 494                           sizeof(buffer->buffer),
 495                           &read_size,
 496                           &overlapped->read_overlapped);
 497         if (!result) {
 498             dwError = GetLastError();
 499             if (dwError == ERROR_IO_PENDING) {
 500                 WaitForSingleObject(overlapped->read_event, INFINITE);
 501                 result = GetOverlappedResult( overlapped->handle, &overlapped->read_overlapped,
 502                                               &read_size, FALSE);
 503                 if (!result) {
 504 #ifdef DEBUG_TAP_WIN32
 505                     LPVOID lpBuffer;
 506                     dwError = GetLastError();
 507                     FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
 508                                    NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 509                                    (LPTSTR) & lpBuffer, 0, NULL );
 510                     fprintf(stderr, "Tap-Win32: Error GetOverlappedResult %d - %s\n", dwError, lpBuffer);
 511                     LocalFree( lpBuffer );
 512 #endif
 513                 }
 514             } else {
 515 #ifdef DEBUG_TAP_WIN32
 516                 LPVOID lpBuffer;
 517                 FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
 518                                NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 519                                (LPTSTR) & lpBuffer, 0, NULL );
 520                 fprintf(stderr, "Tap-Win32: Error ReadFile %d - %s\n", dwError, lpBuffer);
 521                 LocalFree( lpBuffer );
 522 #endif
 523             }
 524         }
 525
 526         if(read_size > 0) {
 527             buffer->read_size = read_size;
 528             put_buffer_on_output_queue(overlapped, buffer);
 529             ReleaseSemaphore(overlapped->tap_semaphore, 1, NULL);
 530             buffer = get_buffer_from_free_list(overlapped);
 531         }
 532     }
 533
 534     return 0;
 535 }
 536
 537 static int tap_win32_read(tap_win32_overlapped_t *overlapped,
 538                           uint8_t **pbuf, int max_size)
 539 {
 540     int size = 0;
 541
 542     tun_buffer_t* buffer = get_buffer_from_output_queue_immediate(overlapped);
 543
 544     if(buffer != NULL) {
 545         *pbuf = buffer->buffer;
 546         size = (int)buffer->read_size;
 547         if(size > max_size) {
 548             size = max_size;
 549         }
 550     }
 551
 552     return size;
 553 }
 554
 555 static void tap_win32_free_buffer(tap_win32_overlapped_t *overlapped,
 556                                   uint8_t *pbuf)
 557 {
 558     tun_buffer_t* buffer = (tun_buffer_t*)pbuf;
 559     put_buffer_on_free_list(overlapped, buffer);
 560 }
 561
 562 static int tap_win32_open(tap_win32_overlapped_t **phandle,
 563                           const char *prefered_name)
 564 {
 565     char device_path[256];
 566     char device_guid[0x100];
 567     int rc;
 568     HANDLE handle;
 569     BOOL bret;
 570     char name_buffer[0x100] = {0, };
 571     struct {
 572         unsigned long major;
 573         unsigned long minor;
 574         unsigned long debug;
 575     } version;
 576     DWORD version_len;
 577     DWORD idThread;
 578     HANDLE hThread;
 579
 580     if (prefered_name != NULL)
 581         snprintf(name_buffer, sizeof(name_buffer), "%s", prefered_name);
 582
 583     rc = get_device_guid(device_guid, sizeof(device_guid), name_buffer, sizeof(name_buffer));
 584     if (rc)
 585         return -1;
 586
 587     snprintf (device_path, sizeof(device_path), "%s%s%s",
 588               USERMODEDEVICEDIR,
 589               device_guid,
 590               TAPSUFFIX);
 591
 592     handle = CreateFile (
 593         device_path,
 594         GENERIC_READ | GENERIC_WRITE,
 595         0,
 596         0,
 597         OPEN_EXISTING,
 598         FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
 599         0 );
 600
 601     if (handle == INVALID_HANDLE_VALUE) {
 602         return -1;
 603     }
 604
 605     bret = DeviceIoControl(handle, TAP_IOCTL_GET_VERSION,
 606                            &version, sizeof (version),
 607                            &version, sizeof (version), &version_len, NULL);
 608
 609     if (bret == FALSE) {
 610         CloseHandle(handle);
 611         return -1;
 612     }
 613
 614     if (!tap_win32_set_status(handle, TRUE)) {
 615         return -1;
 616     }
 617
 618     tap_win32_overlapped_init(&tap_overlapped, handle);
 619
 620     *phandle = &tap_overlapped;
 621
 622     hThread = CreateThread(NULL, 0, tap_win32_thread_entry,
 623                            (LPVOID)&tap_overlapped, 0, &idThread);
 624     return 0;
 625 }
 626
 627 /********************************************/
 628
 629  typedef struct TAPState {
 630      VLANClientState *vc;
 631      tap_win32_overlapped_t *handle;
 632  } TAPState;
 633
 634 static void tap_cleanup(VLANClientState *vc)
 635 {
 636     TAPState *s = vc->opaque;
 637
 638     qemu_del_wait_object(s->handle->tap_semaphore, NULL, NULL);
 639
 640     /* FIXME: need to kill thread and close file handle:
 641        tap_win32_close(s);
 642     */
 643     qemu_free(s);
 644 }
 645
 646 static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
 647 {
 648     TAPState *s = vc->opaque;
 649
 650     return tap_win32_write(s->handle, buf, size);
 651 }
 652
 653 static void tap_win32_send(void *opaque)
 654 {
 655     TAPState *s = opaque;
 656     uint8_t *buf;
 657     int max_size = 4096;
 658     int size;
 659
 660     size = tap_win32_read(s->handle, &buf, max_size);
 661     if (size > 0) {
 662         qemu_send_packet(s->vc, buf, size);
 663         tap_win32_free_buffer(s->handle, buf);
 664     }
 665 }
 666
 667 int tap_win32_init(VLANState *vlan, const char *model,
 668                    const char *name, const char *ifname)
 669 {
 670     TAPState *s;
 671
 672     s = qemu_mallocz(sizeof(TAPState));
 673     if (!s)
 674         return -1;
 675     if (tap_win32_open(&s->handle, ifname) < 0) {
 676         printf("tap: Could not open '%s'\n", ifname);
 677         return -1;
 678     }
 679
 680     s->vc = qemu_new_vlan_client(vlan, model, name, NULL, tap_receive,
 681                                  NULL, tap_cleanup, s);
 682
 683     snprintf(s->vc->info_str, sizeof(s->vc->info_str),
 684              "tap: ifname=%s", ifname);
 685
 686     qemu_add_wait_object(s->handle->tap_semaphore, tap_win32_send, s);
 687     return 0;
 688 }