tap-win32.c

qemu虚拟机代码

            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, NULL, s);
    
    snprintf(s->vc->info_str, sizeof(s->vc->info_str),
             "tap: ifname=%s", ifname);
    tap_win32_state = s;
    return 0;
}