tap win32 support

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1737 c046a42c-6fe2-441c-8c8c-71466251a162

4 files changed, 705 insertions, 3 deletions

diff --git a/Makefile.target b/Makefile.target
index 093d40c8ec..a5a2aa0a5e 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -272,6 +272,9 @@ endif
 # must use static linking to avoid leaving stuff in virtual address space
 VL_OBJS=vl.o osdep.o block.o readline.o monitor.o pci.o console.o
 VL_OBJS+=block-cow.o block-qcow.o aes.o block-vmdk.o block-cloop.o block-dmg.o block-bochs.o block-vpc.o block-vvfat.o
+ifdef CONFIG_WIN32
+VL_OBJS+=tap-win32.o
+endif
 
 SOUND_HW = sb16.o es1370.o
 AUDIODRV = audio.o noaudio.o wavaudio.o
diff --git a/tap-win32.c b/tap-win32.c
new file mode 100644
index 0000000000..32baf22da2
--- /dev/null
+++ b/tap-win32.c
@@ -0,0 +1,680 @@
+/*
+ *  TAP-Win32 -- A kernel driver to provide virtual tap device functionality
+ *               on Windows.  Originally derived from the CIPE-Win32
+ *               project by Damion K. Wilson, with extensive modifications by
+ *               James Yonan.
+ *
+ *  All source code which derives from the CIPE-Win32 project is
+ *  Copyright (C) Damion K. Wilson, 2003, and is released under the
+ *  GPL version 2 (see below).
+ *
+ *  All other source code is Copyright (C) James Yonan, 2003-2004,
+ *  and is released under the GPL version 2 (see below).
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include "vl.h"
+#include <stdio.h>
+#include <windows.h>
+
+/* NOTE: PCIBus is redefined in winddk.h */
+#define PCIBus _PCIBus
+#include <ddk/ntapi.h>
+#include <ddk/winddk.h>
+#include <ddk/ntddk.h>
+#undef PCIBus
+
+//=============
+// TAP IOCTLs
+//=============
+
+#define TAP_CONTROL_CODE(request,method) \
+  CTL_CODE (FILE_DEVICE_UNKNOWN, request, method, FILE_ANY_ACCESS)
+
+#define TAP_IOCTL_GET_MAC               TAP_CONTROL_CODE (1, METHOD_BUFFERED)
+#define TAP_IOCTL_GET_VERSION           TAP_CONTROL_CODE (2, METHOD_BUFFERED)
+#define TAP_IOCTL_GET_MTU               TAP_CONTROL_CODE (3, METHOD_BUFFERED)
+#define TAP_IOCTL_GET_INFO              TAP_CONTROL_CODE (4, METHOD_BUFFERED)
+#define TAP_IOCTL_CONFIG_POINT_TO_POINT TAP_CONTROL_CODE (5, METHOD_BUFFERED)
+#define TAP_IOCTL_SET_MEDIA_STATUS      TAP_CONTROL_CODE (6, METHOD_BUFFERED)
+#define TAP_IOCTL_CONFIG_DHCP_MASQ      TAP_CONTROL_CODE (7, METHOD_BUFFERED)
+#define TAP_IOCTL_GET_LOG_LINE          TAP_CONTROL_CODE (8, METHOD_BUFFERED)
+#define TAP_IOCTL_CONFIG_DHCP_SET_OPT   TAP_CONTROL_CODE (9, METHOD_BUFFERED)
+
+//=================
+// Registry keys
+//=================
+
+#define ADAPTER_KEY "SYSTEM\\CurrentControlSet\\Control\\Class\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
+
+#define NETWORK_CONNECTIONS_KEY "SYSTEM\\CurrentControlSet\\Control\\Network\\{4D36E972-E325-11CE-BFC1-08002BE10318}"
+
+//======================
+// Filesystem prefixes
+//======================
+
+#define USERMODEDEVICEDIR "\\\\.\\Global\\"
+#define TAPSUFFIX         ".tap"
+
+
+//======================
+// Compile time configuration
+//======================
+
+//#define DEBUG_TAP_WIN32 1
+
+#define TUN_ASYNCHRONOUS_WRITES 1
+
+#define TUN_BUFFER_SIZE 1560
+#define TUN_MAX_BUFFER_COUNT 32
+
+/*
+ * The data member "buffer" must be the first element in the tun_buffer
+ * structure. See the function, tap_win32_free_buffer.
+ */
+typedef struct tun_buffer_s {
+    unsigned char buffer [TUN_BUFFER_SIZE];
+    unsigned long read_size;
+    struct tun_buffer_s* next;
+} tun_buffer_t;
+
+typedef struct tap_win32_overlapped {
+    HANDLE handle;
+    HANDLE read_event;
+    HANDLE write_event;
+    HANDLE output_queue_semaphore;
+    HANDLE free_list_semaphore;
+    CRITICAL_SECTION output_queue_cs;
+    CRITICAL_SECTION free_list_cs;
+    OVERLAPPED read_overlapped;
+    OVERLAPPED write_overlapped;
+    tun_buffer_t buffers[TUN_MAX_BUFFER_COUNT];
+    tun_buffer_t* free_list;
+    tun_buffer_t* output_queue_front;
+    tun_buffer_t* output_queue_back;
+} tap_win32_overlapped_t;
+
+static tap_win32_overlapped_t tap_overlapped;
+
+static tun_buffer_t* get_buffer_from_free_list(tap_win32_overlapped_t* const overlapped) 
+{
+    tun_buffer_t* buffer = NULL;
+    WaitForSingleObject(overlapped->free_list_semaphore, INFINITE);
+    EnterCriticalSection(&overlapped->free_list_cs);
+    buffer = overlapped->free_list;
+//    assert(buffer != NULL);
+    overlapped->free_list = buffer->next;
+    LeaveCriticalSection(&overlapped->free_list_cs);
+    buffer->next = NULL;
+    return buffer;
+}
+
+static void put_buffer_on_free_list(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
+{
+    EnterCriticalSection(&overlapped->free_list_cs);
+    buffer->next = overlapped->free_list;
+    overlapped->free_list = buffer;
+    LeaveCriticalSection(&overlapped->free_list_cs);
+    ReleaseSemaphore(overlapped->free_list_semaphore, 1, NULL);
+}
+
+static tun_buffer_t* get_buffer_from_output_queue(tap_win32_overlapped_t* const overlapped, const int block) 
+{
+    tun_buffer_t* buffer = NULL;
+    DWORD result, timeout = block ? INFINITE : 0L;
+
+    // Non-blocking call
+    result = WaitForSingleObject(overlapped->output_queue_semaphore, timeout); 
+
+    switch (result) 
+    { 
+        // The semaphore object was signaled.
+        case WAIT_OBJECT_0: 
+            EnterCriticalSection(&overlapped->output_queue_cs);
+
+            buffer = overlapped->output_queue_front;
+            overlapped->output_queue_front = buffer->next;
+
+            if(overlapped->output_queue_front == NULL) {
+                overlapped->output_queue_back = NULL;
+            }
+
+            LeaveCriticalSection(&overlapped->output_queue_cs);
+            break; 
+
+        // Semaphore was nonsignaled, so a time-out occurred.
+        case WAIT_TIMEOUT: 
+            // Cannot open another window.
+            break; 
+    }
+
+    return buffer;
+}
+
+static tun_buffer_t* get_buffer_from_output_queue_immediate (tap_win32_overlapped_t* const overlapped) 
+{
+    return get_buffer_from_output_queue(overlapped, 0);
+}
+
+static void put_buffer_on_output_queue(tap_win32_overlapped_t* const overlapped, tun_buffer_t* const buffer)
+{
+    EnterCriticalSection(&overlapped->output_queue_cs);
+
+    if(overlapped->output_queue_front == NULL && overlapped->output_queue_back == NULL) {
+        overlapped->output_queue_front = overlapped->output_queue_back = buffer;
+    } else {
+        buffer->next = NULL;
+        overlapped->output_queue_back->next = buffer;
+        overlapped->output_queue_back = buffer;
+    }
+
+    LeaveCriticalSection(&overlapped->output_queue_cs);
+
+    ReleaseSemaphore(overlapped->output_queue_semaphore, 1, NULL);
+}
+
+
+static int is_tap_win32_dev(const char *guid)
+{
+    HKEY netcard_key;
+    LONG status;
+    DWORD len;
+    int i = 0;
+
+    status = RegOpenKeyEx(
+        HKEY_LOCAL_MACHINE,
+        ADAPTER_KEY,
+        0,
+        KEY_READ,
+        &netcard_key);
+
+    if (status != ERROR_SUCCESS) {
+        return FALSE;
+    }
+
+    for (;;) {
+        char enum_name[256];
+        char unit_string[256];
+        HKEY unit_key;
+        char component_id_string[] = "ComponentId";
+        char component_id[256];
+        char net_cfg_instance_id_string[] = "NetCfgInstanceId";
+        char net_cfg_instance_id[256];
+        DWORD data_type;
+
+        len = sizeof (enum_name);
+        status = RegEnumKeyEx(
+            netcard_key,
+            i,
+            enum_name,
+            &len,
+            NULL,
+            NULL,
+            NULL,
+            NULL);
+
+        if (status == ERROR_NO_MORE_ITEMS)
+            break;
+        else if (status != ERROR_SUCCESS) {
+            return FALSE;
+        }
+
+        snprintf (unit_string, sizeof(unit_string), "%s\\%s",
+                  ADAPTER_KEY, enum_name);
+
+        status = RegOpenKeyEx(
+            HKEY_LOCAL_MACHINE,
+            unit_string,
+            0,
+            KEY_READ,
+            &unit_key);
+
+        if (status != ERROR_SUCCESS) {
+            return FALSE;
+        } else {
+            len = sizeof (component_id);
+            status = RegQueryValueEx(
+                unit_key,
+                component_id_string,
+                NULL,
+                &data_type,
+                component_id,
+                &len);
+
+            if (!(status != ERROR_SUCCESS || data_type != REG_SZ)) {
+                len = sizeof (net_cfg_instance_id);
+                status = RegQueryValueEx(
+                    unit_key,
+                    net_cfg_instance_id_string,
+                    NULL,
+                    &data_type,
+                    net_cfg_instance_id,
+                    &len);
+
+                if (status == ERROR_SUCCESS && data_type == REG_SZ) {
+                    if (/* !strcmp (component_id, TAP_COMPONENT_ID) &&*/
+                        !strcmp (net_cfg_instance_id, guid)) {
+                        RegCloseKey (unit_key);
+                        RegCloseKey (netcard_key);
+                        return TRUE;
+                    }
+                }
+            }
+            RegCloseKey (unit_key);
+        }
+        ++i;
+    }
+
+    RegCloseKey (netcard_key);
+    return FALSE;
+}
+
+static int get_device_guid(
+    char *name,
+    int name_size,
+    char *actual_name,
+    int actual_name_size)
+{
+    LONG status;
+    HKEY control_net_key;
+    DWORD len;
+    int i = 0;
+    int stop = 0;
+
+    status = RegOpenKeyEx(
+        HKEY_LOCAL_MACHINE,
+        NETWORK_CONNECTIONS_KEY,
+        0,
+        KEY_READ,
+        &control_net_key);
+
+    if (status != ERROR_SUCCESS) {
+        return -1;
+    }
+
+    while (!stop)
+    {
+        char enum_name[256];
+        char connection_string[256];
+        HKEY connection_key;
+        char name_data[256];
+        DWORD name_type;
+        const char name_string[] = "Name";
+
+        len = sizeof (enum_name);
+        status = RegEnumKeyEx(
+            control_net_key,
+            i,
+            enum_name,
+            &len,
+            NULL,
+            NULL,
+            NULL,
+            NULL);
+
+        if (status == ERROR_NO_MORE_ITEMS)
+            break;
+        else if (status != ERROR_SUCCESS) {
+            return -1;
+        }
+
+        snprintf(connection_string, 
+             sizeof(connection_string),
+             "%s\\%s\\Connection",
+             NETWORK_CONNECTIONS_KEY, enum_name);
+
+        status = RegOpenKeyEx(
+            HKEY_LOCAL_MACHINE,
+            connection_string,
+            0,
+            KEY_READ,
+            &connection_key);
+        
+        if (status == ERROR_SUCCESS) {
+            len = sizeof (name_data);
+            status = RegQueryValueEx(
+                connection_key,
+                name_string,
+                NULL,
+                &name_type,
+                name_data,
+                &len);
+
+            if (status != ERROR_SUCCESS || name_type != REG_SZ) {
+                    return -1;
+            }
+            else {
+                if (is_tap_win32_dev(enum_name)) {
+                    snprintf(name, name_size, "%s", enum_name);
+                    if (actual_name) {
+                        if (strcmp(actual_name, "") != 0) {
+                            if (strcmp(name_data, actual_name) != 0) {
+                                RegCloseKey (connection_key);
+                                ++i;
+                                continue;
+                            }
+                        }
+                        else {
+                            snprintf(actual_name, actual_name_size, "%s", name_data);
+                        }
+                    }
+                    stop = 1;
+                }
+            }
+
+            RegCloseKey (connection_key);
+        }
+        ++i;
+    }
+
+    RegCloseKey (control_net_key);
+
+    if (stop == 0)
+        return -1;
+
+    return 0;
+}
+
+static int tap_win32_set_status(HANDLE handle, int status)
+{
+    unsigned long len = 0;
+
+    return DeviceIoControl(handle, TAP_IOCTL_SET_MEDIA_STATUS,
+                &status, sizeof (status),
+                &status, sizeof (status), &len, NULL);
+}
+
+static void tap_win32_overlapped_init(tap_win32_overlapped_t* const overlapped, const HANDLE handle)
+{
+    overlapped->handle = handle;
+
+    overlapped->read_event = CreateEvent(NULL, FALSE, FALSE, NULL);
+    overlapped->write_event = CreateEvent(NULL, FALSE, FALSE, NULL);
+
+    overlapped->read_overlapped.Offset = 0;
+    overlapped->read_overlapped.OffsetHigh = 0;
+    overlapped->read_overlapped.hEvent = overlapped->read_event;
+
+    overlapped->write_overlapped.Offset = 0;
+    overlapped->write_overlapped.OffsetHigh = 0;
+    overlapped->write_overlapped.hEvent = overlapped->write_event;
+
+    InitializeCriticalSection(&overlapped->output_queue_cs);
+    InitializeCriticalSection(&overlapped->free_list_cs);
+
+    overlapped->output_queue_semaphore = CreateSemaphore( 
+        NULL,   // default security attributes
+        0,   // initial count
+        TUN_MAX_BUFFER_COUNT,   // maximum count
+        NULL);  // unnamed semaphore
+
+    if(!overlapped->output_queue_semaphore)  {
+        fprintf(stderr, "error creating output queue semaphore!\n");
+    }
+
+    overlapped->free_list_semaphore = CreateSemaphore( 
+        NULL,   // default security attributes
+        TUN_MAX_BUFFER_COUNT,   // initial count
+        TUN_MAX_BUFFER_COUNT,   // maximum count
+        NULL);  // unnamed semaphore
+
+    if(!overlapped->free_list_semaphore)  {
+        fprintf(stderr, "error creating free list semaphore!\n");
+    }
+
+    overlapped->free_list = overlapped->output_queue_front = overlapped->output_queue_back = NULL;
+
+    {
+        unsigned index;
+        for(index = 0; index < TUN_MAX_BUFFER_COUNT; index++) {
+            tun_buffer_t* element = &overlapped->buffers[index];
+            element->next = overlapped->free_list;
+            overlapped->free_list = element;
+        }
+    }
+}
+
+static int tap_win32_write(tap_win32_overlapped_t *overlapped, 
+                           const void *buffer, unsigned long size)
+{
+    unsigned long write_size;
+    BOOL result;
+    DWORD error;
+
+    result = GetOverlappedResult( overlapped->handle, &overlapped->write_overlapped,
+                                  &write_size, FALSE);
+
+    if (!result && GetLastError() == ERROR_IO_INCOMPLETE)
+        WaitForSingleObject(overlapped->write_event, INFINITE);
+
+    result = WriteFile(overlapped->handle, buffer, size,
+                       &write_size, &overlapped->write_overlapped);
+    
+    if (!result) { 
+        switch (error = GetLastError())
+        { 
+        case ERROR_IO_PENDING: 
+#ifndef TUN_ASYNCHRONOUS_WRITES
+            WaitForSingleObject(overlapped->write_event, INFINITE);
+#endif
+            break;
+        default:
+            return -1;
+        } 
+    }
+
+    return 0;
+}
+
+static DWORD WINAPI tap_win32_thread_entry(LPVOID param)
+{
+    tap_win32_overlapped_t *overlapped = (tap_win32_overlapped_t*)param;
+    unsigned long read_size;
+    BOOL result;
+    DWORD dwError;
+    tun_buffer_t* buffer = get_buffer_from_free_list(overlapped);
+
+
+    for (;;) {
+        result = ReadFile(overlapped->handle,
+                          buffer->buffer,
+                          sizeof(buffer->buffer),
+                          &read_size,
+                          &overlapped->read_overlapped);
+        if (!result) {
+            dwError = GetLastError();
+            if (dwError == ERROR_IO_PENDING) {
+                WaitForSingleObject(overlapped->read_event, INFINITE);
+                result = GetOverlappedResult( overlapped->handle, &overlapped->read_overlapped,
+                                              &read_size, FALSE);
+                if (!result) {
+#if DEBUG_TAP_WIN32
+                    LPVOID lpBuffer;
+                    dwError = GetLastError();
+                    FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
+                                   NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                                   (LPTSTR) & lpBuffer, 0, NULL );
+                    fprintf(stderr, "Tap-Win32: Error GetOverlappedResult %d - %s\n", dwError, lpBuffer);
+                    LocalFree( lpBuffer );
+#endif
+                }
+            } else {
+#if DEBUG_TAP_WIN32
+                LPVOID lpBuffer;
+                FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
+                               NULL, dwError, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                               (LPTSTR) & lpBuffer, 0, NULL );
+                fprintf(stderr, "Tap-Win32: Error ReadFile %d - %s\n", dwError, lpBuffer);
+                LocalFree( lpBuffer );
+#endif
+            }
+        }
+
+        if(read_size > 0) {
+            buffer->read_size = read_size;
+            put_buffer_on_output_queue(overlapped, buffer);
+            buffer = get_buffer_from_free_list(overlapped);
+        }
+    }
+
+    return 0;
+}
+
+static int tap_win32_read(tap_win32_overlapped_t *overlapped, 
+                          uint8_t **pbuf, int max_size)
+{
+    int size = 0;
+
+    tun_buffer_t* buffer = get_buffer_from_output_queue_immediate(overlapped);
+
+    if(buffer != NULL) {
+        *pbuf = buffer->buffer;
+        size = (int)buffer->read_size;
+        if(size > max_size) {
+            size = max_size;
+        }
+    }
+
+    return size;
+}
+
+static void tap_win32_free_buffer(tap_win32_overlapped_t *overlapped, 
+                                  char* pbuf) 
+{
+    tun_buffer_t* buffer = (tun_buffer_t*)pbuf;
+    put_buffer_on_free_list(overlapped, buffer);
+}
+
+static int tap_win32_open(tap_win32_overlapped_t **phandle, 
+                          const char *prefered_name)
+{
+    char device_path[256];
+    char device_guid[0x100];
+    int rc;
+    HANDLE handle;
+    BOOL bret;
+    char name_buffer[0x100] = {0, };
+    struct {
+        unsigned long major;
+        unsigned long minor;
+        unsigned long debug;
+    } version;
+    LONG version_len;
+    DWORD idThread;
+    HANDLE hThread;
+
+    if (prefered_name != NULL)
+        snprintf(name_buffer, sizeof(name_buffer), "%s", prefered_name);
+
+    rc = get_device_guid(device_guid, sizeof(device_guid), name_buffer, sizeof(name_buffer));
+    if (rc)
+        return -1;
+
+    snprintf (device_path, sizeof(device_path), "%s%s%s",
+              USERMODEDEVICEDIR,
+              device_guid,
+              TAPSUFFIX);
+
+    handle = CreateFile (
+        device_path,
+        GENERIC_READ | GENERIC_WRITE,
+        0,
+        0,
+        OPEN_EXISTING,
+        FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
+        0 );
+
+    if (handle == INVALID_HANDLE_VALUE) {
+        return -1;
+    }
+
+    bret = DeviceIoControl(handle, TAP_IOCTL_GET_VERSION,
+                           &version, sizeof (version),
+                           &version, sizeof (version), &version_len, NULL);
+
+    if (bret == FALSE) {
+        CloseHandle(handle);
+        return -1;
+    }
+
+    if (!tap_win32_set_status(handle, TRUE)) {
+        return -1;
+    }
+
+    tap_win32_overlapped_init(&tap_overlapped, handle);
+
+    *phandle = &tap_overlapped;
+
+    hThread = CreateThread(NULL, 0, tap_win32_thread_entry,
+                           (LPVOID)&tap_overlapped, 0, &idThread);
+    SetThreadPriority(hThread,THREAD_PRIORITY_TIME_CRITICAL);
+
+    return 0;
+}
+
+/********************************************/
+
+ typedef struct TAPState {
+     VLANClientState *vc;
+     tap_win32_overlapped_t *handle;
+ } TAPState;
+
+static TAPState *tap_win32_state = NULL;
+
+static void tap_receive(void *opaque, const uint8_t *buf, int size)
+{
+    TAPState *s = opaque;
+
+    tap_win32_write(s->handle, buf, size);
+}
+
+/* XXX: horrible, suppress this by using proper thread signaling */
+void tap_win32_poll(void)
+{
+    TAPState *s = tap_win32_state;
+    uint8_t *buf;
+    int max_size = 4096;
+    int size;
+
+    if (!s)
+        return;
+
+    size = tap_win32_read(s->handle, &buf, max_size);
+    if (size > 0) {
+        qemu_send_packet(s->vc, buf, size);
+        tap_win32_free_buffer(s->handle, buf);
+    }
+}
+
+int tap_win32_init(VLANState *vlan, const char *ifname)
+{
+    TAPState *s;
+    
+    s = qemu_mallocz(sizeof(TAPState));
+    if (!s)
+        return -1;
+    if (tap_win32_open(&s->handle, ifname) < 0) {
+        printf("tap: Could not open '%s'\n", ifname);
+        return -1;
+    }
+
+    s->vc = qemu_new_vlan_client(vlan, tap_receive, s);
+    
+    snprintf(s->vc->info_str, sizeof(s->vc->info_str),
+             "tap: ifname=%s", ifname);
+    tap_win32_state = s;
+    return 0;
+}
diff --git a/vl.c b/vl.c
index 47056f8945..d875f2ac0a 100644
--- a/vl.c
+++ b/vl.c
@@ -2715,7 +2715,16 @@ int net_client_init(const char *str)
         ret = net_slirp_init(vlan);
     } else
 #endif
-#ifndef _WIN32
+#ifdef _WIN32
+    if (!strcmp(device, "tap")) {
+        char ifname[64];
+        if (get_param_value(ifname, sizeof(ifname), "ifname", p) <= 0) {
+            fprintf(stderr, "tap: no interface name\n");
+            return -1;
+        }
+        ret = tap_win32_init(vlan, ifname);
+    } else
+#else
     if (!strcmp(device, "tap")) {
         char ifname[64];
         char setup_script[1024];
@@ -3947,6 +3956,9 @@ void main_loop_wait(int timeout)
             }
         }
     }
+#ifdef _WIN32
+    tap_win32_poll();
+#endif
 
 #if defined(CONFIG_SLIRP)
     /* XXX: merge with the previous select() */
@@ -4087,16 +4099,19 @@ void help(void)
            "-net user[,vlan=n]\n"
            "                connect the user mode network stack to VLAN 'n'\n"
 #endif
-#ifndef _WIN32
+#ifdef _WIN32
+           "-net tap[,vlan=n],ifname=name\n"
+           "                connect the host TAP network interface to VLAN 'n'\n"
+#else
            "-net tap[,vlan=n][,fd=h][,ifname=name][,script=file]\n"
            "                connect the host TAP network interface to VLAN 'n' and use\n"
            "                the network script 'file' (default=%s);\n"
            "                use 'fd=h' to connect to an already opened TAP interface\n"
+#endif
            "-net socket[,vlan=n][,fd=h][,listen=[host]:port][,connect=host:port]\n"
            "                connect the vlan 'n' to another VLAN using a socket connection\n"
            "-net socket[,vlan=n][,fd=h][,mcast=maddr:port]\n"
            "                connect the vlan 'n' to multicast maddr and port\n"
-#endif
            "-net none       use it alone to have zero network devices; if no -net option\n"
            "                is provided, the default is '-net nic -net user'\n"
            "\n"
diff --git a/vl.h b/vl.h
index 7a107281d6..004498f6d4 100644
--- a/vl.h
+++ b/vl.h
@@ -298,6 +298,10 @@ void qemu_send_packet(VLANClientState *vc, const uint8_t *buf, int size);
 
 void do_info_network(void);
 
+/* TAP win32 */
+int tap_win32_init(VLANState *vlan, const char *ifname);
+void tap_win32_poll(void);
+
 /* NIC info */
 
 #define MAX_NICS 8