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, write to the Free Software Foundation, Inc.,
  27  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  28  */
  29 #include "qemu-common.h"
  30 #include "net.h"
  31 #include "sysemu.h"
  32 #include <stdio.h>
  33 #include <windows.h>
  34
  35 /* NOTE: PCIBus is redefined in winddk.h */
  36 #define PCIBus _PCIBus
  37 #include <ddk/ntapi.h>
  38 #include <ddk/winddk.h>
  39 #include <ddk/ntddk.h>
  40 #undef PCIBus
  41
  42 //=============
  43 // TAP IOCTLs
  44 //=============
  45
  46 #define TAP_CONTROL_CODE(request,method) \
  47   CTL_CODE (FILE_DEVICE_UNKNOWN, request, method, FILE_ANY_ACCESS)
  48
  49 #define TAP_IOCTL_GET_MAC               TAP_CONTROL_CODE (1, METHOD_BUFFERED)
  50 #define TAP_IOCTL_GET_VERSION           TAP_CONTROL_CODE (2, METHOD_BUFFERED)
  51 #define TAP_IOCTL_GET_MTU               TAP_CONTROL_CODE (3, METHOD_BUFFERED)
  52 #define TAP_IOCTL_GET_INFO              TAP_CONTROL_CODE (4, METHOD_BUFFERED)
  53 #define TAP_IOCTL_CONFIG_POINT_TO_POINT TAP_CONTROL_CODE (5, METHOD_BUFFERED)
  54 #define TAP_IOCTL_SET_MEDIA_STATUS      TAP_CONTROL_CODE (6, METHOD_BUFFERED)
  55 #define TAP_IOCTL_CONFIG_DHCP_MASQ      TAP_CONTROL_CODE (7, METHOD_BUFFERED)
  56 #define TAP_IOCTL_GET_LOG_LINE          TAP_CONTROL_CODE (8, METHOD_BUFFERED)
  57 #define TAP_IOCTL_CONFIG_DHCP_SET_OPT   TAP_CONTROL_CODE (9, METHOD_BUFFERED)
  58
  59 //=================
  60 // Registry keys
  61 //=================
  62
  63 #define ADAPTER_KEY "SYSTEM\\CurrentControlSet\\Control\\Class\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
  64
  65 #define NETWORK_CONNECTIONS_KEY "SYSTEM\\CurrentControlSet\\Control\\Network\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
  66
  67 //======================
  68 // Filesystem prefixes
  69 //======================
  70
  71 #define USERMODEDEVICEDIR "\\\\.\\Global\\"
  72 #define TAPSUFFIX         ".tap"
  73
  74
  75 //======================
  76 // Compile time configuration
  77 //======================
  78
  79 //#define DEBUG_TAP_WIN32 1
  80
  81 #define TUN_ASYNCHRONOUS_WRITES 1
  82
  83 #define TUN_BUFFER_SIZE 1560
  84 #define TUN_MAX_BUFFER_COUNT 32
  85
  86 /*
  87  * The data member "buffer" must be the first element in the tun_buffer
  88  * structure. See the function, tap_win32_free_buffer.
  89  */
  90 typedef struct tun_buffer_s {
  91     unsigned char buffer [TUN_BUFFER_SIZE];
  92     unsigned long read_size;
  93     struct tun_buffer_s* next;
  94 } tun_buffer_t;
  95
  96 typedef struct tap_win32_overlapped {
  97     HANDLE handle;
  98     HANDLE read_event;
  99     HANDLE write_event;
 100     HANDLE output_queue_semaphore;
 101     HANDLE free_list_semaphore;
 102     HANDLE tap_semaphore;
 103     CRITICAL_SECTION output_queue_cs;
 104     CRITICAL_SECTION free_list_cs;
 105     OVERLAPPED read_overlapped;
 106     OVERLAPPED write_overlapped;
 107     tun_buffer_t buffers[TUN_MAX_BUFFER_COUNT];
 108     tun_buffer_t* free_list;
 109     tun_buffer_t* output_queue_front;
 110     tun_buffer_t* output_queue_back;
 111 } tap_win32_overlapped_t;
 112
 113 static tap_win32_overlapped_t tap_overlapped;
 114
 115 static tun_buffer_t* get_buffer_from_free_list(tap_win32_overlapped_t* const overlapped)
 116 {
 117     tun_buffer_t* buffer = NULL;
 118     WaitForSingleObject(overlapped->free_list_semaphore, INFINITE);
 119     EnterCriticalSection(&overlapped->free_list_cs);
 120     buffer = overlapped->free_list;
 121 //    assert(buffer != NULL);
 122     overlapped->free_list = buffer->next;
 123     LeaveCriticalSection(&overlapped->free_list_cs);
 124     buffer->next = NULL;
 125     return buffer;
 126 }
 127
 128 static void put_buffer_on_free_list(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
 129 {
 130     EnterCriticalSection(&overlapped->free_list_cs);
 131     buffer->next = overlapped->free_list;
 132     overlapped->free_list = buffer;
 133     LeaveCriticalSection(&overlapped->free_list_cs);
 134     ReleaseSemaphore(overlapped->free_list_semaphore, 1, NULL);
 135 }
 136
 137 static tun_buffer_t* get_buffer_from_output_queue(tap_win32_overlapped_t* const overlapped, const int block)
 138 {
 139     tun_buffer_t* buffer = NULL;
 140     DWORD result, timeout = block ? INFINITE : 0L;
 141
 142     // Non-blocking call
 143     result = WaitForSingleObject(overlapped->output_queue_semaphore, timeout);
 144
 145     switch (result)
 146     {
 147         // The semaphore object was signaled.
 148         case WAIT_OBJECT_0:
 149             EnterCriticalSection(&overlapped->output_queue_cs);
 150
 151             buffer = overlapped->output_queue_front;
 152             overlapped->output_queue_front = buffer->next;
 153
 154             if(overlapped->output_queue_front == NULL) {
 155                 overlapped->output_queue_back = NULL;
 156             }
 157
 158             LeaveCriticalSection(&overlapped->output_queue_cs);
 159             break;
 160
 161         // Semaphore was nonsignaled, so a time-out occurred.
 162         case WAIT_TIMEOUT:
 163             // Cannot open another window.
 164             break;
 165     }
 166
 167     return buffer;
 168 }
 169
 170 static tun_buffer_t* get_buffer_from_output_queue_immediate (tap_win32_overlapped_t* const overlapped)
 171 {
 172     return get_buffer_from_output_queue(overlapped, 0);
 173 }
 174
 175 static void put_buffer_on_output_queue(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
 176 {
 177     EnterCriticalSection(&overlapped->output_queue_cs);
 178
 179     if(overlapped->output_queue_front == NULL && overlapped->output_queue_back == NULL) {
 180         overlapped->output_queue_front = overlapped->output_queue_back = buffer;
 181     } else {
 182         buffer->next = NULL;
 183         overlapped->output_queue_back->next = buffer;
 184         overlapped->output_queue_back = buffer;
 185     }
 186
 187     LeaveCriticalSection(&overlapped->output_queue_cs);
 188
 189     ReleaseSemaphore(overlapped->output_queue_semaphore, 1, NULL);
 190 }
 191
 192
 193 static int is_tap_win32_dev(const char *guid)
 194 {
 195     HKEY netcard_key;
 196     LONG status;
 197     DWORD len;
 198     int i = 0;
 199
 200     status = RegOpenKeyEx(
 201         HKEY_LOCAL_MACHINE,
 202         ADAPTER_KEY,
 203         0,
 204         KEY_READ,
 205         &netcard_key);
 206
 207     if (status != ERROR_SUCCESS) {
 208         return FALSE;
 209     }
 210
 211     for (;;) {
 212         char enum_name[256];
 213         char unit_string[256];
 214         HKEY unit_key;
 215         char component_id_string[] = "ComponentId";
 216         char component_id[256];
 217         char net_cfg_instance_id_string[] = "NetCfgInstanceId";
 218         char net_cfg_instance_id[256];
 219         DWORD data_type;
 220
 221         len = sizeof (enum_name);
 222         status = RegEnumKeyEx(
 223             netcard_key,
 224             i,
 225             enum_name,
 226             &len,
 227             NULL,
 228             NULL,
 229             NULL,
 230             NULL);
 231
 232         if (status == ERROR_NO_MORE_ITEMS)
 233             break;
 234         else if (status != ERROR_SUCCESS) {
 235             return FALSE;
 236         }
 237
 238         snprintf (unit_string, sizeof(unit_string), "%s\\%s",
 239                   ADAPTER_KEY, enum_name);
 240
 241         status = RegOpenKeyEx(
 242             HKEY_LOCAL_MACHINE,
 243             unit_string,
 244             0,
 245             KEY_READ,
 246             &unit_key);
 247
 248         if (status != ERROR_SUCCESS) {
 249             return FALSE;
 250         } else {
 251             len = sizeof (component_id);
 252             status = RegQueryValueEx(
 253                 unit_key,
 254                 component_id_string,
 255                 NULL,
 256                 &data_type,
 257                 component_id,
 258                 &len);
 259
 260             if (!(status != ERROR_SUCCESS || data_type != REG_SZ)) {
 261                 len = sizeof (net_cfg_instance_id);
 262                 status = RegQueryValueEx(
 263                     unit_key,
 264                     net_cfg_instance_id_string,
 265                     NULL,
 266                     &data_type,
 267                     net_cfg_instance_id,
 268                     &len);
 269
 270                 if (status == ERROR_SUCCESS && data_type == REG_SZ) {
 271                     if (/* !strcmp (component_id, TAP_COMPONENT_ID) &&*/
 272                         !strcmp (net_cfg_instance_id, guid)) {
 273                         RegCloseKey (unit_key);
 274                         RegCloseKey (netcard_key);
 275                         return TRUE;
 276                     }
 277                 }
 278             }
 279             RegCloseKey (unit_key);
 280         }
 281         ++i;
 282     }
 283
 284     RegCloseKey (netcard_key);
 285     return FALSE;
 286 }
 287
 288 static int get_device_guid(
 289     char *name,
 290     int name_size,
 291     char *actual_name,
 292     int actual_name_size)
 293 {
 294     LONG status;
 295     HKEY control_net_key;
 296     DWORD len;
 297     int i = 0;
 298     int stop = 0;
 299
 300     status = RegOpenKeyEx(
 301         HKEY_LOCAL_MACHINE,
 302         NETWORK_CONNECTIONS_KEY,
 303         0,
 304         KEY_READ,
 305         &control_net_key);
 306
 307     if (status != ERROR_SUCCESS) {
 308         return -1;
 309     }
 310
 311     while (!stop)
 312     {
 313         char enum_name[256];
 314         char connection_string[256];
 315         HKEY connection_key;
 316         char name_data[256];
 317         DWORD name_type;
 318         const char name_string[] = "Name";
 319
 320         len = sizeof (enum_name);
 321         status = RegEnumKeyEx(
 322             control_net_key,
 323             i,
 324             enum_name,
 325             &len,
 326             NULL,
 327             NULL,
 328             NULL,
 329             NULL);
 330
 331         if (status == ERROR_NO_MORE_ITEMS)
 332             break;
 333         else if (status != ERROR_SUCCESS) {
 334             return -1;
 335         }
 336
 337         snprintf(connection_string,
 338              sizeof(connection_string),
 339              "%s\\%s\\Connection",
 340              NETWORK_CONNECTIONS_KEY, enum_name);
 341
 342         status = RegOpenKeyEx(
 343             HKEY_LOCAL_MACHINE,
 344             connection_string,
 345             0,
 346             KEY_READ,
 347             &connection_key);
 348
 349         if (status == ERROR_SUCCESS) {
 350             len = sizeof (name_data);
 351             status = RegQueryValueEx(
 352                 connection_key,
 353                 name_string,
 354                 NULL,
 355                 &name_type,
 356                 name_data,
 357                 &len);
 358
 359             if (status != ERROR_SUCCESS || name_type != REG_SZ) {
 360                     return -1;
 361             }
 362             else {
 363                 if (is_tap_win32_dev(enum_name)) {
 364                     snprintf(name, name_size, "%s", enum_name);
 365                     if (actual_name) {
 366                         if (strcmp(actual_name, "") != 0) {
 367                             if (strcmp(name_data, actual_name) != 0) {
 368                                 RegCloseKey (connection_key);
 369                                 ++i;
 370                                 continue;
 371                             }
 372                         }
 373                         else {
 374                             snprintf(actual_name, actual_name_size, "%s", name_data);
 375                         }
 376                     }
 377                     stop = 1;
 378                 }
 379             }
 380
 381             RegCloseKey (connection_key);
 382         }
 383         ++i;
 384     }
 385
 386     RegCloseKey (control_net_key);
 387
 388     if (stop == 0)
 389         return -1;
 390
 391     return 0;
 392 }
 393
 394 static int tap_win32_set_status(HANDLE handle, int status)
 395 {
 396     unsigned long len = 0;
 397
 398     return DeviceIoControl(handle, TAP_IOCTL_SET_MEDIA_STATUS,
 399                 &status, sizeof (status),
 400                 &status, sizeof (status), &len, NULL);
 401 }
 402
 403 static void tap_win32_overlapped_init(tap_win32_overlapped_t* const overlapped, const HANDLE handle)
 404 {
 405     overlapped->handle = handle;
 406
 407     overlapped->read_event = CreateEvent(NULL, FALSE, FALSE, NULL);
 408     overlapped->write_event = CreateEvent(NULL, FALSE, FALSE, NULL);
 409
 410     overlapped->read_overlapped.Offset = 0;
 411     overlapped->read_overlapped.OffsetHigh = 0;
 412     overlapped->read_overlapped.hEvent = overlapped->read_event;
 413
 414     overlapped->write_overlapped.Offset = 0;
 415     overlapped->write_overlapped.OffsetHigh = 0;
 416     overlapped->write_overlapped.hEvent = overlapped->write_event;
 417
 418     InitializeCriticalSection(&overlapped->output_queue_cs);
 419     InitializeCriticalSection(&overlapped->free_list_cs);
 420
 421     overlapped->output_queue_semaphore = CreateSemaphore(
 422         NULL,   // default security attributes
 423         0,   // initial count
 424         TUN_MAX_BUFFER_COUNT,   // maximum count
 425         NULL);  // unnamed semaphore
 426
 427     if(!overlapped->output_queue_semaphore)  {
 428         fprintf(stderr, "error creating output queue semaphore!\n");
 429     }
 430
 431     overlapped->free_list_semaphore = CreateSemaphore(
 432         NULL,   // default security attributes
 433         TUN_MAX_BUFFER_COUNT,   // initial count
 434         TUN_MAX_BUFFER_COUNT,   // maximum count
 435         NULL);  // unnamed semaphore
 436
 437     if(!overlapped->free_list_semaphore)  {
 438         fprintf(stderr, "error creating free list semaphore!\n");
 439     }
 440
 441     overlapped->free_list = overlapped->output_queue_front = overlapped->output_queue_back = NULL;
 442
 443     {
 444         unsigned index;
 445         for(index = 0; index < TUN_MAX_BUFFER_COUNT; index++) {
 446             tun_buffer_t* element = &overlapped->buffers[index];
 447             element->next = overlapped->free_list;
 448             overlapped->free_list = element;
 449         }
 450     }
 451     /* To count buffers, initially no-signal. */
 452     overlapped->tap_semaphore = CreateSemaphore(NULL, 0, TUN_MAX_BUFFER_COUNT, NULL);
 453     if(!overlapped->tap_semaphore)
 454         fprintf(stderr, "error creating tap_semaphore.\n");
 455 }
 456
 457 static int tap_win32_write(tap_win32_overlapped_t *overlapped,
 458                            const void *buffer, unsigned long size)
 459 {
 460     unsigned long write_size;
 461     BOOL result;
 462     DWORD error;
 463
 464     result = GetOverlappedResult( overlapped->handle, &overlapped->write_overlapped,
 465                                   &write_size, FALSE);
 466
 467     if (!result && GetLastError() == ERROR_IO_INCOMPLETE)
 468         WaitForSingleObject(overlapped->write_event, INFINITE);
 469
 470     result = WriteFile(overlapped->handle, buffer, size,
 471                        &write_size, &overlapped->write_overlapped);
 472
 473     if (!result) {
 474         switch (error = GetLastError())
 475         {
 476         case ERROR_IO_PENDING:
 477 #ifndef TUN_ASYNCHRONOUS_WRITES
 478             WaitForSingleObject(overlapped->write_event, INFINITE);
 479 #endif
 480             break;
 481         default:
 482             return -1;
 483         }
 484     }
 485
 486     return 0;
 487 }
 488
 489 static DWORD WINAPI tap_win32_thread_entry(LPVOID param)
 490 {
 491     tap_win32_overlapped_t *overlapped = (tap_win32_overlapped_t*)param;
 492     unsigned long read_size;
 493     BOOL result;
 494     DWORD dwError;
 495     tun_buffer_t* buffer = get_buffer_from_free_list(overlapped);
 496
 497
 498     for (;;) {
 499         result = ReadFile(overlapped->handle,
 500                           buffer->buffer,
 501                           sizeof(buffer->buffer),
 502                           &read_size,
 503                           &overlapped->read_overlapped);
 504         if (!result) {
 505             dwError = GetLastError();
 506             if (dwError == ERROR_IO_PENDING) {
 507                 WaitForSingleObject(overlapped->read_event, INFINITE);
 508                 result = GetOverlappedResult( overlapped->handle, &overlapped->read_overlapped,
 509                                               &read_size, FALSE);
 510                 if (!result) {
 511 #if DEBUG_TAP_WIN32
 512                     LPVOID lpBuffer;
 513                     dwError = GetLastError();
 514                     FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
 515                                    NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 516                                    (LPTSTR) & lpBuffer, 0, NULL );
 517                     fprintf(stderr, "Tap-Win32: Error GetOverlappedResult %d - %s\n", dwError, lpBuffer);
 518                     LocalFree( lpBuffer );
 519 #endif
 520                 }
 521             } else {
 522 #if DEBUG_TAP_WIN32
 523                 LPVOID lpBuffer;
 524                 FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
 525                                NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 526                                (LPTSTR) & lpBuffer, 0, NULL );
 527                 fprintf(stderr, "Tap-Win32: Error ReadFile %d - %s\n", dwError, lpBuffer);
 528                 LocalFree( lpBuffer );
 529 #endif
 530             }
 531         }
 532
 533         if(read_size > 0) {
 534             buffer->read_size = read_size;
 535             put_buffer_on_output_queue(overlapped, buffer);
 536             ReleaseSemaphore(overlapped->tap_semaphore, 1, NULL);
 537             buffer = get_buffer_from_free_list(overlapped);
 538         }
 539     }
 540
 541     return 0;
 542 }
 543
 544 static int tap_win32_read(tap_win32_overlapped_t *overlapped,
 545                           uint8_t **pbuf, int max_size)
 546 {
 547     int size = 0;
 548
 549     tun_buffer_t* buffer = get_buffer_from_output_queue_immediate(overlapped);
 550
 551     if(buffer != NULL) {
 552         *pbuf = buffer->buffer;
 553         size = (int)buffer->read_size;
 554         if(size > max_size) {
 555             size = max_size;
 556         }
 557     }
 558
 559     return size;
 560 }
 561
 562 static void tap_win32_free_buffer(tap_win32_overlapped_t *overlapped,
 563                                   char* pbuf)
 564 {
 565     tun_buffer_t* buffer = (tun_buffer_t*)pbuf;
 566     put_buffer_on_free_list(overlapped, buffer);
 567 }
 568
 569 static int tap_win32_open(tap_win32_overlapped_t **phandle,
 570                           const char *prefered_name)
 571 {
 572     char device_path[256];
 573     char device_guid[0x100];
 574     int rc;
 575     HANDLE handle;
 576     BOOL bret;
 577     char name_buffer[0x100] = {0, };
 578     struct {
 579         unsigned long major;
 580         unsigned long minor;
 581         unsigned long debug;
 582     } version;
 583     LONG version_len;
 584     DWORD idThread;
 585     HANDLE hThread;
 586
 587     if (prefered_name != NULL)
 588         snprintf(name_buffer, sizeof(name_buffer), "%s", prefered_name);
 589
 590     rc = get_device_guid(device_guid, sizeof(device_guid), name_buffer, sizeof(name_buffer));
 591     if (rc)
 592         return -1;
 593
 594     snprintf (device_path, sizeof(device_path), "%s%s%s",
 595               USERMODEDEVICEDIR,
 596               device_guid,
 597               TAPSUFFIX);
 598
 599     handle = CreateFile (
 600         device_path,
 601         GENERIC_READ | GENERIC_WRITE,
 602         0,
 603         0,
 604         OPEN_EXISTING,
 605         FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
 606         0 );
 607
 608     if (handle == INVALID_HANDLE_VALUE) {
 609         return -1;
 610     }
 611
 612     bret = DeviceIoControl(handle, TAP_IOCTL_GET_VERSION,
 613                            &version, sizeof (version),
 614                            &version, sizeof (version), &version_len, NULL);
 615
 616     if (bret == FALSE) {
 617         CloseHandle(handle);
 618         return -1;
 619     }
 620
 621     if (!tap_win32_set_status(handle, TRUE)) {
 622         return -1;
 623     }
 624
 625     tap_win32_overlapped_init(&tap_overlapped, handle);
 626
 627     *phandle = &tap_overlapped;
 628
 629     hThread = CreateThread(NULL, 0, tap_win32_thread_entry,
 630                            (LPVOID)&tap_overlapped, 0, &idThread);
 631     return 0;
 632 }
 633
 634 /********************************************/
 635
 636  typedef struct TAPState {
 637      VLANClientState *vc;
 638      tap_win32_overlapped_t *handle;
 639  } TAPState;
 640
 641 static void tap_receive(void *opaque, const uint8_t *buf, int size)
 642 {
 643     TAPState *s = opaque;
 644
 645     tap_win32_write(s->handle, buf, size);
 646 }
 647
 648 static void tap_win32_send(void *opaque)
 649 {
 650     TAPState *s = opaque;
 651     uint8_t *buf;
 652     int max_size = 4096;
 653     int size;
 654
 655     size = tap_win32_read(s->handle, &buf, max_size);
 656     if (size > 0) {
 657         qemu_send_packet(s->vc, buf, size);
 658         tap_win32_free_buffer(s->handle, buf);
 659     }
 660 }
 661
 662 int tap_win32_init(VLANState *vlan, const char *ifname)
 663 {
 664     TAPState *s;
 665
 666     s = qemu_mallocz(sizeof(TAPState));
 667     if (!s)
 668         return -1;
 669     if (tap_win32_open(&s->handle, ifname) < 0) {
 670         printf("tap: Could not open '%s'\n", ifname);
 671         return -1;
 672     }
 673
 674     s->vc = qemu_new_vlan_client(vlan, tap_receive, NULL, s);
 675
 676     snprintf(s->vc->info_str, sizeof(s->vc->info_str),
 677              "tap: ifname=%s", ifname);
 678
 679     qemu_add_wait_object(s->handle->tap_semaphore, tap_win32_send, s);
 680     return 0;
 681 }