net/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
  29 #include "net/tap.h"
  30
  31 #include "qemu-common.h"
  32 #include "net.h"
  33 #include "sysemu.h"
  34 #include <stdio.h>
  35 #include <windows.h>
  36 #include <winioctl.h>
  37
  38 //=============
  39 // TAP IOCTLs
  40 //=============
  41
  42 #define TAP_CONTROL_CODE(request,method) \
  43   CTL_CODE (FILE_DEVICE_UNKNOWN, request, method, FILE_ANY_ACCESS)
  44
  45 #define TAP_IOCTL_GET_MAC               TAP_CONTROL_CODE (1, METHOD_BUFFERED)
  46 #define TAP_IOCTL_GET_VERSION           TAP_CONTROL_CODE (2, METHOD_BUFFERED)
  47 #define TAP_IOCTL_GET_MTU               TAP_CONTROL_CODE (3, METHOD_BUFFERED)
  48 #define TAP_IOCTL_GET_INFO              TAP_CONTROL_CODE (4, METHOD_BUFFERED)
  49 #define TAP_IOCTL_CONFIG_POINT_TO_POINT TAP_CONTROL_CODE (5, METHOD_BUFFERED)
  50 #define TAP_IOCTL_SET_MEDIA_STATUS      TAP_CONTROL_CODE (6, METHOD_BUFFERED)
  51 #define TAP_IOCTL_CONFIG_DHCP_MASQ      TAP_CONTROL_CODE (7, METHOD_BUFFERED)
  52 #define TAP_IOCTL_GET_LOG_LINE          TAP_CONTROL_CODE (8, METHOD_BUFFERED)
  53 #define TAP_IOCTL_CONFIG_DHCP_SET_OPT   TAP_CONTROL_CODE (9, METHOD_BUFFERED)
  54
  55 //=================
  56 // Registry keys
  57 //=================
  58
  59 #define ADAPTER_KEY "SYSTEM\\CurrentControlSet\\Control\\Class\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
  60
  61 #define NETWORK_CONNECTIONS_KEY "SYSTEM\\CurrentControlSet\\Control\\Network\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
  62
  63 //======================
  64 // Filesystem prefixes
  65 //======================
  66
  67 #define USERMODEDEVICEDIR "\\\\.\\Global\\"
  68 #define TAPSUFFIX         ".tap"
  69
  70
  71 //======================
  72 // Compile time configuration
  73 //======================
  74
  75 //#define DEBUG_TAP_WIN32
  76
  77 #define TUN_ASYNCHRONOUS_WRITES 1
  78
  79 #define TUN_BUFFER_SIZE 1560
  80 #define TUN_MAX_BUFFER_COUNT 32
  81
  82 /*
  83  * The data member "buffer" must be the first element in the tun_buffer
  84  * structure. See the function, tap_win32_free_buffer.
  85  */
  86 typedef struct tun_buffer_s {
  87     unsigned char buffer [TUN_BUFFER_SIZE];
  88     unsigned long read_size;
  89     struct tun_buffer_s* next;
  90 } tun_buffer_t;
  91
  92 typedef struct tap_win32_overlapped {
  93     HANDLE handle;
  94     HANDLE read_event;
  95     HANDLE write_event;
  96     HANDLE output_queue_semaphore;
  97     HANDLE free_list_semaphore;
  98     HANDLE tap_semaphore;
  99     CRITICAL_SECTION output_queue_cs;
 100     CRITICAL_SECTION free_list_cs;
 101     OVERLAPPED read_overlapped;
 102     OVERLAPPED write_overlapped;
 103     tun_buffer_t buffers[TUN_MAX_BUFFER_COUNT];
 104     tun_buffer_t* free_list;
 105     tun_buffer_t* output_queue_front;
 106     tun_buffer_t* output_queue_back;
 107 } tap_win32_overlapped_t;
 108
 109 static tap_win32_overlapped_t tap_overlapped;
 110
 111 static tun_buffer_t* get_buffer_from_free_list(tap_win32_overlapped_t* const overlapped)
 112 {
 113     tun_buffer_t* buffer = NULL;
 114     WaitForSingleObject(overlapped->free_list_semaphore, INFINITE);
 115     EnterCriticalSection(&overlapped->free_list_cs);
 116     buffer = overlapped->free_list;
 117 //    assert(buffer != NULL);
 118     overlapped->free_list = buffer->next;
 119     LeaveCriticalSection(&overlapped->free_list_cs);
 120     buffer->next = NULL;
 121     return buffer;
 122 }
 123
 124 static void put_buffer_on_free_list(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
 125 {
 126     EnterCriticalSection(&overlapped->free_list_cs);
 127     buffer->next = overlapped->free_list;
 128     overlapped->free_list = buffer;
 129     LeaveCriticalSection(&overlapped->free_list_cs);
 130     ReleaseSemaphore(overlapped->free_list_semaphore, 1, NULL);
 131 }
 132
 133 static tun_buffer_t* get_buffer_from_output_queue(tap_win32_overlapped_t* const overlapped, const int block)
 134 {
 135     tun_buffer_t* buffer = NULL;
 136     DWORD result, timeout = block ? INFINITE : 0L;
 137
 138     // Non-blocking call
 139     result = WaitForSingleObject(overlapped->output_queue_semaphore, timeout);
 140
 141     switch (result)
 142     {
 143         // The semaphore object was signaled.
 144         case WAIT_OBJECT_0:
 145             EnterCriticalSection(&overlapped->output_queue_cs);
 146
 147             buffer = overlapped->output_queue_front;
 148             overlapped->output_queue_front = buffer->next;
 149
 150             if(overlapped->output_queue_front == NULL) {
 151                 overlapped->output_queue_back = NULL;
 152             }
 153
 154             LeaveCriticalSection(&overlapped->output_queue_cs);
 155             break;
 156
 157         // Semaphore was nonsignaled, so a time-out occurred.
 158         case WAIT_TIMEOUT:
 159             // Cannot open another window.
 160             break;
 161     }
 162
 163     return buffer;
 164 }
 165
 166 static tun_buffer_t* get_buffer_from_output_queue_immediate (tap_win32_overlapped_t* const overlapped)
 167 {
 168     return get_buffer_from_output_queue(overlapped, 0);
 169 }
 170
 171 static void put_buffer_on_output_queue(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
 172 {
 173     EnterCriticalSection(&overlapped->output_queue_cs);
 174
 175     if(overlapped->output_queue_front == NULL && overlapped->output_queue_back == NULL) {
 176         overlapped->output_queue_front = overlapped->output_queue_back = buffer;
 177     } else {
 178         buffer->next = NULL;
 179         overlapped->output_queue_back->next = buffer;
 180         overlapped->output_queue_back = buffer;
 181     }
 182
 183     LeaveCriticalSection(&overlapped->output_queue_cs);
 184
 185     ReleaseSemaphore(overlapped->output_queue_semaphore, 1, NULL);
 186 }
 187
 188
 189 static int is_tap_win32_dev(const char *guid)
 190 {
 191     HKEY netcard_key;
 192     LONG status;
 193     DWORD len;
 194     int i = 0;
 195
 196     status = RegOpenKeyEx(
 197         HKEY_LOCAL_MACHINE,
 198         ADAPTER_KEY,
 199         0,
 200         KEY_READ,
 201         &netcard_key);
 202
 203     if (status != ERROR_SUCCESS) {
 204         return FALSE;
 205     }
 206
 207     for (;;) {
 208         char enum_name[256];
 209         char unit_string[256];
 210         HKEY unit_key;
 211         char component_id_string[] = "ComponentId";
 212         char component_id[256];
 213         char net_cfg_instance_id_string[] = "NetCfgInstanceId";
 214         char net_cfg_instance_id[256];
 215         DWORD data_type;
 216
 217         len = sizeof (enum_name);
 218         status = RegEnumKeyEx(
 219             netcard_key,
 220             i,
 221             enum_name,
 222             &len,
 223             NULL,
 224             NULL,
 225             NULL,
 226             NULL);
 227
 228         if (status == ERROR_NO_MORE_ITEMS)
 229             break;
 230         else if (status != ERROR_SUCCESS) {
 231             return FALSE;
 232         }
 233
 234         snprintf (unit_string, sizeof(unit_string), "%s\\%s",
 235                   ADAPTER_KEY, enum_name);
 236
 237         status = RegOpenKeyEx(
 238             HKEY_LOCAL_MACHINE,
 239             unit_string,
 240             0,
 241             KEY_READ,
 242             &unit_key);
 243
 244         if (status != ERROR_SUCCESS) {
 245             return FALSE;
 246         } else {
 247             len = sizeof (component_id);
 248             status = RegQueryValueEx(
 249                 unit_key,
 250                 component_id_string,
 251                 NULL,
 252                 &data_type,
 253                 (LPBYTE)component_id,
 254                 &len);
 255
 256             if (!(status != ERROR_SUCCESS || data_type != REG_SZ)) {
 257                 len = sizeof (net_cfg_instance_id);
 258                 status = RegQueryValueEx(
 259                     unit_key,
 260                     net_cfg_instance_id_string,
 261                     NULL,
 262                     &data_type,
 263                     (LPBYTE)net_cfg_instance_id,
 264                     &len);
 265
 266                 if (status == ERROR_SUCCESS && data_type == REG_SZ) {
 267                     if (/* !strcmp (component_id, TAP_COMPONENT_ID) &&*/
 268                         !strcmp (net_cfg_instance_id, guid)) {
 269                         RegCloseKey (unit_key);
 270                         RegCloseKey (netcard_key);
 271                         return TRUE;
 272                     }
 273                 }
 274             }
 275             RegCloseKey (unit_key);
 276         }
 277         ++i;
 278     }
 279
 280     RegCloseKey (netcard_key);
 281     return FALSE;
 282 }
 283
 284 static int get_device_guid(
 285     char *name,
 286     int name_size,
 287     char *actual_name,
 288     int actual_name_size)
 289 {
 290     LONG status;
 291     HKEY control_net_key;
 292     DWORD len;
 293     int i = 0;
 294     int stop = 0;
 295
 296     status = RegOpenKeyEx(
 297         HKEY_LOCAL_MACHINE,
 298         NETWORK_CONNECTIONS_KEY,
 299         0,
 300         KEY_READ,
 301         &control_net_key);
 302
 303     if (status != ERROR_SUCCESS) {
 304         return -1;
 305     }
 306
 307     while (!stop)
 308     {
 309         char enum_name[256];
 310         char connection_string[256];
 311         HKEY connection_key;
 312         char name_data[256];
 313         DWORD name_type;
 314         const char name_string[] = "Name";
 315
 316         len = sizeof (enum_name);
 317         status = RegEnumKeyEx(
 318             control_net_key,
 319             i,
 320             enum_name,
 321             &len,
 322             NULL,
 323             NULL,
 324             NULL,
 325             NULL);
 326
 327         if (status == ERROR_NO_MORE_ITEMS)
 328             break;
 329         else if (status != ERROR_SUCCESS) {
 330             return -1;
 331         }
 332
 333         snprintf(connection_string,
 334              sizeof(connection_string),
 335              "%s\\%s\\Connection",
 336              NETWORK_CONNECTIONS_KEY, enum_name);
 337
 338         status = RegOpenKeyEx(
 339             HKEY_LOCAL_MACHINE,
 340             connection_string,
 341             0,
 342             KEY_READ,
 343             &connection_key);
 344
 345         if (status == ERROR_SUCCESS) {
 346             len = sizeof (name_data);
 347             status = RegQueryValueEx(
 348                 connection_key,
 349                 name_string,
 350                 NULL,
 351                 &name_type,
 352                 (LPBYTE)name_data,
 353                 &len);
 354
 355             if (status != ERROR_SUCCESS || name_type != REG_SZ) {
 356                     return -1;
 357             }
 358             else {
 359                 if (is_tap_win32_dev(enum_name)) {
 360                     snprintf(name, name_size, "%s", enum_name);
 361                     if (actual_name) {
 362                         if (strcmp(actual_name, "") != 0) {
 363                             if (strcmp(name_data, actual_name) != 0) {
 364                                 RegCloseKey (connection_key);
 365                                 ++i;
 366                                 continue;
 367                             }
 368                         }
 369                         else {
 370                             snprintf(actual_name, actual_name_size, "%s", name_data);
 371                         }
 372                     }
 373                     stop = 1;
 374                 }
 375             }
 376
 377             RegCloseKey (connection_key);
 378         }
 379         ++i;
 380     }
 381
 382     RegCloseKey (control_net_key);
 383
 384     if (stop == 0)
 385         return -1;
 386
 387     return 0;
 388 }
 389
 390 static int tap_win32_set_status(HANDLE handle, int status)
 391 {
 392     unsigned long len = 0;
 393
 394     return DeviceIoControl(handle, TAP_IOCTL_SET_MEDIA_STATUS,
 395                 &status, sizeof (status),
 396                 &status, sizeof (status), &len, NULL);
 397 }
 398
 399 static void tap_win32_overlapped_init(tap_win32_overlapped_t* const overlapped, const HANDLE handle)
 400 {
 401     overlapped->handle = handle;
 402
 403     overlapped->read_event = CreateEvent(NULL, FALSE, FALSE, NULL);
 404     overlapped->write_event = CreateEvent(NULL, FALSE, FALSE, NULL);
 405
 406     overlapped->read_overlapped.Offset = 0;
 407     overlapped->read_overlapped.OffsetHigh = 0;
 408     overlapped->read_overlapped.hEvent = overlapped->read_event;
 409
 410     overlapped->write_overlapped.Offset = 0;
 411     overlapped->write_overlapped.OffsetHigh = 0;
 412     overlapped->write_overlapped.hEvent = overlapped->write_event;
 413
 414     InitializeCriticalSection(&overlapped->output_queue_cs);
 415     InitializeCriticalSection(&overlapped->free_list_cs);
 416
 417     overlapped->output_queue_semaphore = CreateSemaphore(
 418         NULL,   // default security attributes
 419         0,   // initial count
 420         TUN_MAX_BUFFER_COUNT,   // maximum count
 421         NULL);  // unnamed semaphore
 422
 423     if(!overlapped->output_queue_semaphore)  {
 424         fprintf(stderr, "error creating output queue semaphore!\n");
 425     }
 426
 427     overlapped->free_list_semaphore = CreateSemaphore(
 428         NULL,   // default security attributes
 429         TUN_MAX_BUFFER_COUNT,   // initial count
 430         TUN_MAX_BUFFER_COUNT,   // maximum count
 431         NULL);  // unnamed semaphore
 432
 433     if(!overlapped->free_list_semaphore)  {
 434         fprintf(stderr, "error creating free list semaphore!\n");
 435     }
 436
 437     overlapped->free_list = overlapped->output_queue_front = overlapped->output_queue_back = NULL;
 438
 439     {
 440         unsigned index;
 441         for(index = 0; index < TUN_MAX_BUFFER_COUNT; index++) {
 442             tun_buffer_t* element = &overlapped->buffers[index];
 443             element->next = overlapped->free_list;
 444             overlapped->free_list = element;
 445         }
 446     }
 447     /* To count buffers, initially no-signal. */
 448     overlapped->tap_semaphore = CreateSemaphore(NULL, 0, TUN_MAX_BUFFER_COUNT, NULL);
 449     if(!overlapped->tap_semaphore)
 450         fprintf(stderr, "error creating tap_semaphore.\n");
 451 }
 452
 453 static int tap_win32_write(tap_win32_overlapped_t *overlapped,
 454                            const void *buffer, unsigned long size)
 455 {
 456     unsigned long write_size;
 457     BOOL result;
 458     DWORD error;
 459
 460     result = GetOverlappedResult( overlapped->handle, &overlapped->write_overlapped,
 461                                   &write_size, FALSE);
 462
 463     if (!result && GetLastError() == ERROR_IO_INCOMPLETE)
 464         WaitForSingleObject(overlapped->write_event, INFINITE);
 465
 466     result = WriteFile(overlapped->handle, buffer, size,
 467                        &write_size, &overlapped->write_overlapped);
 468
 469     if (!result) {
 470         switch (error = GetLastError())
 471         {
 472         case ERROR_IO_PENDING:
 473 #ifndef TUN_ASYNCHRONOUS_WRITES
 474             WaitForSingleObject(overlapped->write_event, INFINITE);
 475 #endif
 476             break;
 477         default:
 478             return -1;
 479         }
 480     }
 481
 482     return 0;
 483 }
 484
 485 static DWORD WINAPI tap_win32_thread_entry(LPVOID param)
 486 {
 487     tap_win32_overlapped_t *overlapped = (tap_win32_overlapped_t*)param;
 488     unsigned long read_size;
 489     BOOL result;
 490     DWORD dwError;
 491     tun_buffer_t* buffer = get_buffer_from_free_list(overlapped);
 492
 493
 494     for (;;) {
 495         result = ReadFile(overlapped->handle,
 496                           buffer->buffer,
 497                           sizeof(buffer->buffer),
 498                           &read_size,
 499                           &overlapped->read_overlapped);
 500         if (!result) {
 501             dwError = GetLastError();
 502             if (dwError == ERROR_IO_PENDING) {
 503                 WaitForSingleObject(overlapped->read_event, INFINITE);
 504                 result = GetOverlappedResult( overlapped->handle, &overlapped->read_overlapped,
 505                                               &read_size, FALSE);
 506                 if (!result) {
 507 #ifdef DEBUG_TAP_WIN32
 508                     LPVOID lpBuffer;
 509                     dwError = GetLastError();
 510                     FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
 511                                    NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 512                                    (LPTSTR) & lpBuffer, 0, NULL );
 513                     fprintf(stderr, "Tap-Win32: Error GetOverlappedResult %d - %s\n", dwError, lpBuffer);
 514                     LocalFree( lpBuffer );
 515 #endif
 516                 }
 517             } else {
 518 #ifdef DEBUG_TAP_WIN32
 519                 LPVOID lpBuffer;
 520                 FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
 521                                NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
 522                                (LPTSTR) & lpBuffer, 0, NULL );
 523                 fprintf(stderr, "Tap-Win32: Error ReadFile %d - %s\n", dwError, lpBuffer);
 524                 LocalFree( lpBuffer );
 525 #endif
 526             }
 527         }
 528
 529         if(read_size > 0) {
 530             buffer->read_size = read_size;
 531             put_buffer_on_output_queue(overlapped, buffer);
 532             ReleaseSemaphore(overlapped->tap_semaphore, 1, NULL);
 533             buffer = get_buffer_from_free_list(overlapped);
 534         }
 535     }
 536
 537     return 0;
 538 }
 539
 540 static int tap_win32_read(tap_win32_overlapped_t *overlapped,
 541                           uint8_t **pbuf, int max_size)
 542 {
 543     int size = 0;
 544
 545     tun_buffer_t* buffer = get_buffer_from_output_queue_immediate(overlapped);
 546
 547     if(buffer != NULL) {
 548         *pbuf = buffer->buffer;
 549         size = (int)buffer->read_size;
 550         if(size > max_size) {
 551             size = max_size;
 552         }
 553     }
 554
 555     return size;
 556 }
 557
 558 static void tap_win32_free_buffer(tap_win32_overlapped_t *overlapped,
 559                                   uint8_t *pbuf)
 560 {
 561     tun_buffer_t* buffer = (tun_buffer_t*)pbuf;
 562     put_buffer_on_free_list(overlapped, buffer);
 563 }
 564
 565 static int tap_win32_open(tap_win32_overlapped_t **phandle,
 566                           const char *prefered_name)
 567 {
 568     char device_path[256];
 569     char device_guid[0x100];
 570     int rc;
 571     HANDLE handle;
 572     BOOL bret;
 573     char name_buffer[0x100] = {0, };
 574     struct {
 575         unsigned long major;
 576         unsigned long minor;
 577         unsigned long debug;
 578     } version;
 579     DWORD version_len;
 580     DWORD idThread;
 581     HANDLE hThread;
 582
 583     if (prefered_name != NULL)
 584         snprintf(name_buffer, sizeof(name_buffer), "%s", prefered_name);
 585
 586     rc = get_device_guid(device_guid, sizeof(device_guid), name_buffer, sizeof(name_buffer));
 587     if (rc)
 588         return -1;
 589
 590     snprintf (device_path, sizeof(device_path), "%s%s%s",
 591               USERMODEDEVICEDIR,
 592               device_guid,
 593               TAPSUFFIX);
 594
 595     handle = CreateFile (
 596         device_path,
 597         GENERIC_READ | GENERIC_WRITE,
 598         0,
 599         0,
 600         OPEN_EXISTING,
 601         FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
 602         0 );
 603
 604     if (handle == INVALID_HANDLE_VALUE) {
 605         return -1;
 606     }
 607
 608     bret = DeviceIoControl(handle, TAP_IOCTL_GET_VERSION,
 609                            &version, sizeof (version),
 610                            &version, sizeof (version), &version_len, NULL);
 611
 612     if (bret == FALSE) {
 613         CloseHandle(handle);
 614         return -1;
 615     }
 616
 617     if (!tap_win32_set_status(handle, TRUE)) {
 618         return -1;
 619     }
 620
 621     tap_win32_overlapped_init(&tap_overlapped, handle);
 622
 623     *phandle = &tap_overlapped;
 624
 625     hThread = CreateThread(NULL, 0, tap_win32_thread_entry,
 626                            (LPVOID)&tap_overlapped, 0, &idThread);
 627     return 0;
 628 }
 629
 630 /********************************************/
 631
 632  typedef struct TAPState {
 633      VLANClientState *vc;
 634      tap_win32_overlapped_t *handle;
 635  } TAPState;
 636
 637 static void tap_cleanup(VLANClientState *vc)
 638 {
 639     TAPState *s = vc->opaque;
 640
 641     qemu_del_wait_object(s->handle->tap_semaphore, NULL, NULL);
 642
 643     /* FIXME: need to kill thread and close file handle:
 644        tap_win32_close(s);
 645     */
 646     qemu_free(s);
 647 }
 648
 649 static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
 650 {
 651     TAPState *s = vc->opaque;
 652
 653     return tap_win32_write(s->handle, buf, size);
 654 }
 655
 656 static void tap_win32_send(void *opaque)
 657 {
 658     TAPState *s = opaque;
 659     uint8_t *buf;
 660     int max_size = 4096;
 661     int size;
 662
 663     size = tap_win32_read(s->handle, &buf, max_size);
 664     if (size > 0) {
 665         qemu_send_packet(s->vc, buf, size);
 666         tap_win32_free_buffer(s->handle, buf);
 667     }
 668 }
 669
 670 static int tap_win32_init(VLANState *vlan, const char *model,
 671                           const char *name, const char *ifname)
 672 {
 673     TAPState *s;
 674
 675     s = qemu_mallocz(sizeof(TAPState));
 676     if (!s)
 677         return -1;
 678     if (tap_win32_open(&s->handle, ifname) < 0) {
 679         printf("tap: Could not open '%s'\n", ifname);
 680         return -1;
 681     }
 682
 683     s->vc = qemu_new_vlan_client(NET_CLIENT_TYPE_TAP,
 684                                  vlan, NULL, model, name,
 685                                  NULL, tap_receive,
 686                                  NULL, NULL, tap_cleanup, s);
 687
 688     snprintf(s->vc->info_str, sizeof(s->vc->info_str),
 689              "tap: ifname=%s", ifname);
 690
 691     qemu_add_wait_object(s->handle->tap_semaphore, tap_win32_send, s);
 692     return 0;
 693 }
 694
 695 int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan)
 696 {
 697     const char *ifname;
 698
 699     ifname = qemu_opt_get(opts, "ifname");
 700
 701     if (!ifname) {
 702         qemu_error("tap: no interface name\n");
 703         return -1;
 704     }
 705
 706     if (tap_win32_init(vlan, "tap", name, ifname) == -1) {
 707         return -1;
 708     }
 709
 710     if (vlan) {
 711         vlan->nb_host_devs++;
 712     }
 713
 714     return 0;
 715 }
 716
 717 int tap_has_ufo(VLANClientState *vc)
 718 {
 719     return 0;
 720 }
 721
 722 int tap_has_vnet_hdr(VLANClientState *vc)
 723 {
 724     return 0;
 725 }
 726
 727 void tap_using_vnet_hdr(VLANClientState *vc, int using_vnet_hdr)
 728 {
 729 }
 730
 731 void tap_set_offload(VLANClientState *vc, int csum, int tso4,
 732                      int tso6, int ecn, int ufo)
 733 {
 734 }