gwj / at91sam9263 · Files

/*
 * QEMU VNC display driver

 *

 * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
 * Copyright (C) 2006 Fabrice Bellard

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu-common.h"
#include "console.h"
#include "sysemu.h"

#include "qemu_socket.h"

#include "qemu-timer.h"

#define VNC_REFRESH_INTERVAL (1000 / 30)

#include "vnc_keysym.h"
#include "keymaps.c"

#include "d3des.h"

#ifdef CONFIG_VNC_TLS

#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#endif /* CONFIG_VNC_TLS */

// #define _VNC_DEBUG 1

#ifdef _VNC_DEBUG

#define VNC_DEBUG(fmt, ...) do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)

#if CONFIG_VNC_TLS && _VNC_DEBUG >= 2
/* Very verbose, so only enabled for _VNC_DEBUG >= 2 */
static void vnc_debug_gnutls_log(int level, const char* str) {
    VNC_DEBUG("%d %s", level, str);
}
#endif /* CONFIG_VNC_TLS && _VNC_DEBUG */

#else
#define VNC_DEBUG(fmt, ...) do { } while (0)
#endif

typedef struct Buffer
{
    size_t capacity;
    size_t offset;

    uint8_t *buffer;

} Buffer;

typedef struct VncState VncState;

typedef int VncReadEvent(VncState *vs, uint8_t *data, size_t len);

typedef void VncWritePixels(VncState *vs, void *data, int size);

typedef void VncSendHextileTile(VncState *vs,
                                int x, int y, int w, int h,

                                void *last_bg,
                                void *last_fg,

                                int *has_bg, int *has_fg);

#define VNC_MAX_WIDTH 2048
#define VNC_MAX_HEIGHT 2048
#define VNC_DIRTY_WORDS (VNC_MAX_WIDTH / (16 * 32))

#define VNC_AUTH_CHALLENGE_SIZE 16

enum {
    VNC_AUTH_INVALID = 0,
    VNC_AUTH_NONE = 1,
    VNC_AUTH_VNC = 2,
    VNC_AUTH_RA2 = 5,
    VNC_AUTH_RA2NE = 6,
    VNC_AUTH_TIGHT = 16,
    VNC_AUTH_ULTRA = 17,
    VNC_AUTH_TLS = 18,
    VNC_AUTH_VENCRYPT = 19
};

#ifdef CONFIG_VNC_TLS

enum {
    VNC_WIREMODE_CLEAR,
    VNC_WIREMODE_TLS,
};

enum {
    VNC_AUTH_VENCRYPT_PLAIN = 256,
    VNC_AUTH_VENCRYPT_TLSNONE = 257,
    VNC_AUTH_VENCRYPT_TLSVNC = 258,
    VNC_AUTH_VENCRYPT_TLSPLAIN = 259,
    VNC_AUTH_VENCRYPT_X509NONE = 260,
    VNC_AUTH_VENCRYPT_X509VNC = 261,
    VNC_AUTH_VENCRYPT_X509PLAIN = 262,
};

#define X509_CA_CERT_FILE "ca-cert.pem"
#define X509_CA_CRL_FILE "ca-crl.pem"
#define X509_SERVER_KEY_FILE "server-key.pem"
#define X509_SERVER_CERT_FILE "server-cert.pem"

#endif /* CONFIG_VNC_TLS */

struct VncState
{
    QEMUTimer *timer;
    int lsock;
    int csock;
    DisplayState *ds;
    int need_update;
    int width;
    int height;

    uint32_t dirty_row[VNC_MAX_HEIGHT][VNC_DIRTY_WORDS];

    char *old_data;

    int depth; /* internal VNC frame buffer byte per pixel */

    int has_resize;
    int has_hextile;

    int has_pointer_type_change;

    int has_WMVi;

    int absolute;
    int last_x;
    int last_y;

    int major;
    int minor;

    char *display;

    char *password;
    int auth;

#ifdef CONFIG_VNC_TLS

    int subauth;

    int x509verify;

    char *x509cacert;
    char *x509cacrl;
    char *x509cert;
    char *x509key;

#endif

    char challenge[VNC_AUTH_CHALLENGE_SIZE];

#ifdef CONFIG_VNC_TLS

    int wiremode;
    gnutls_session_t tls_session;
#endif

    Buffer output;
    Buffer input;
    kbd_layout_t *kbd_layout;

    /* current output mode information */
    VncWritePixels *write_pixels;
    VncSendHextileTile *send_hextile_tile;
    int pix_bpp, pix_big_endian;

    int client_red_shift, client_red_max, server_red_shift, server_red_max;
    int client_green_shift, client_green_max, server_green_shift, server_green_max;
    int client_blue_shift, client_blue_max, server_blue_shift, server_blue_max;

    VncReadEvent *read_handler;
    size_t read_handler_expect;

    /* input */
    uint8_t modifiers_state[256];

};

static VncState *vnc_state; /* needed for info vnc */

void do_info_vnc(void)
{
    if (vnc_state == NULL)
	term_printf("VNC server disabled\n");
    else {
	term_printf("VNC server active on: ");
	term_print_filename(vnc_state->display);
	term_printf("\n");

	if (vnc_state->csock == -1)
	    term_printf("No client connected\n");
	else
	    term_printf("Client connected\n");
    }
}

/* TODO
   1) Get the queue working for IO.
   2) there is some weirdness when using the -S option (the screen is grey
      and not totally invalidated
   3) resolutions > 1024
*/

static void vnc_write(VncState *vs, const void *data, size_t len);
static void vnc_write_u32(VncState *vs, uint32_t value);
static void vnc_write_s32(VncState *vs, int32_t value);
static void vnc_write_u16(VncState *vs, uint16_t value);
static void vnc_write_u8(VncState *vs, uint8_t value);
static void vnc_flush(VncState *vs);
static void vnc_update_client(void *opaque);
static void vnc_client_read(void *opaque);

static void vnc_colordepth(DisplayState *ds, int depth);

static inline void vnc_set_bit(uint32_t *d, int k)
{
    d[k >> 5] |= 1 << (k & 0x1f);
}

static inline void vnc_clear_bit(uint32_t *d, int k)
{
    d[k >> 5] &= ~(1 << (k & 0x1f));
}

static inline void vnc_set_bits(uint32_t *d, int n, int nb_words)
{
    int j;

    j = 0;
    while (n >= 32) {
        d[j++] = -1;
        n -= 32;
    }

    if (n > 0)

        d[j++] = (1 << n) - 1;
    while (j < nb_words)
        d[j++] = 0;
}

static inline int vnc_get_bit(const uint32_t *d, int k)
{
    return (d[k >> 5] >> (k & 0x1f)) & 1;
}

static inline int vnc_and_bits(const uint32_t *d1, const uint32_t *d2,

                               int nb_words)
{
    int i;
    for(i = 0; i < nb_words; i++) {
        if ((d1[i] & d2[i]) != 0)
            return 1;
    }
    return 0;
}

static void vnc_dpy_update(DisplayState *ds, int x, int y, int w, int h)
{
    VncState *vs = ds->opaque;
    int i;

    h += y;

    /* round x down to ensure the loop only spans one 16-pixel block per,
       iteration.  otherwise, if (x % 16) != 0, the last iteration may span
       two 16-pixel blocks but we only mark the first as dirty
    */
    w += (x % 16);
    x -= (x % 16);

    x = MIN(x, vs->width);
    y = MIN(y, vs->height);
    w = MIN(x + w, vs->width) - x;

    h = MIN(h, vs->height);

    for (; y < h; y++)
	for (i = 0; i < w; i += 16)

	    vnc_set_bit(vs->dirty_row[y], (x + i) / 16);

}

static void vnc_framebuffer_update(VncState *vs, int x, int y, int w, int h,
				   int32_t encoding)
{
    vnc_write_u16(vs, x);
    vnc_write_u16(vs, y);
    vnc_write_u16(vs, w);
    vnc_write_u16(vs, h);

    vnc_write_s32(vs, encoding);
}

static void vnc_dpy_resize(DisplayState *ds, int w, int h)
{

    int size_changed;

    VncState *vs = ds->opaque;

    ds->data = qemu_realloc(ds->data, w * h * vs->depth);
    vs->old_data = qemu_realloc(vs->old_data, w * h * vs->depth);

    if (ds->data == NULL || vs->old_data == NULL) {
	fprintf(stderr, "vnc: memory allocation failed\n");
	exit(1);
    }

    if (ds->depth != vs->depth * 8) {
        ds->depth = vs->depth * 8;
        console_color_init(ds);
    }

    size_changed = ds->width != w || ds->height != h;

    ds->width = w;
    ds->height = h;
    ds->linesize = w * vs->depth;

    if (size_changed) {
        vs->width = ds->width;
        vs->height = ds->height;
        if (vs->csock != -1 && vs->has_resize) {
            vnc_write_u8(vs, 0);  /* msg id */
            vnc_write_u8(vs, 0);
            vnc_write_u16(vs, 1); /* number of rects */
            vnc_framebuffer_update(vs, 0, 0, ds->width, ds->height, -223);
            vnc_flush(vs);
        }

    }

    memset(vs->dirty_row, 0xFF, sizeof(vs->dirty_row));
    memset(vs->old_data, 42, vs->ds->linesize * vs->ds->height);

}

/* fastest code */
static void vnc_write_pixels_copy(VncState *vs, void *pixels, int size)
{
    vnc_write(vs, pixels, size);
}

/* slowest but generic code. */
static void vnc_convert_pixel(VncState *vs, uint8_t *buf, uint32_t v)
{

    uint8_t r, g, b;

    r = ((v >> vs->server_red_shift) & vs->server_red_max) * (vs->client_red_max + 1) /
        (vs->server_red_max + 1);
    g = ((v >> vs->server_green_shift) & vs->server_green_max) * (vs->client_green_max + 1) /
        (vs->server_green_max + 1);
    b = ((v >> vs->server_blue_shift) & vs->server_blue_max) * (vs->client_blue_max + 1) /
        (vs->server_blue_max + 1);
    v = (r << vs->client_red_shift) |
        (g << vs->client_green_shift) |
        (b << vs->client_blue_shift);

    switch(vs->pix_bpp) {
    case 1:
        buf[0] = v;
        break;
    case 2:
        if (vs->pix_big_endian) {
            buf[0] = v >> 8;
            buf[1] = v;
        } else {
            buf[1] = v >> 8;
            buf[0] = v;
        }
        break;
    default:
    case 4:
        if (vs->pix_big_endian) {
            buf[0] = v >> 24;
            buf[1] = v >> 16;
            buf[2] = v >> 8;
            buf[3] = v;
        } else {
            buf[3] = v >> 24;
            buf[2] = v >> 16;
            buf[1] = v >> 8;
            buf[0] = v;
        }
        break;
    }
}

static void vnc_write_pixels_generic(VncState *vs, void *pixels1, int size)
{
    uint8_t buf[4];

    if (vs->depth == 4) {
        uint32_t *pixels = pixels1;
        int n, i;
        n = size >> 2;
        for(i = 0; i < n; i++) {
            vnc_convert_pixel(vs, buf, pixels[i]);
            vnc_write(vs, buf, vs->pix_bpp);
        }
    } else if (vs->depth == 2) {
        uint16_t *pixels = pixels1;
        int n, i;
        n = size >> 1;
        for(i = 0; i < n; i++) {
            vnc_convert_pixel(vs, buf, pixels[i]);
            vnc_write(vs, buf, vs->pix_bpp);
        }
    } else if (vs->depth == 1) {
        uint8_t *pixels = pixels1;
        int n, i;
        n = size;
        for(i = 0; i < n; i++) {
            vnc_convert_pixel(vs, buf, pixels[i]);
            vnc_write(vs, buf, vs->pix_bpp);
        }
    } else {
        fprintf(stderr, "vnc_write_pixels_generic: VncState color depth not supported\n");

    }
}

static void send_framebuffer_update_raw(VncState *vs, int x, int y, int w, int h)
{
    int i;

    uint8_t *row;

    vnc_framebuffer_update(vs, x, y, w, h, 0);

    row = vs->ds->data + y * vs->ds->linesize + x * vs->depth;
    for (i = 0; i < h; i++) {

	vs->write_pixels(vs, row, w * vs->depth);

	row += vs->ds->linesize;
    }
}

static void hextile_enc_cord(uint8_t *ptr, int x, int y, int w, int h)
{
    ptr[0] = ((x & 0x0F) << 4) | (y & 0x0F);
    ptr[1] = (((w - 1) & 0x0F) << 4) | ((h - 1) & 0x0F);
}

#define BPP 8
#include "vnchextile.h"
#undef BPP

#define BPP 16
#include "vnchextile.h"
#undef BPP

#define BPP 32
#include "vnchextile.h"
#undef BPP

#define GENERIC

#define BPP 8
#include "vnchextile.h"
#undef BPP
#undef GENERIC

#define GENERIC
#define BPP 16
#include "vnchextile.h"
#undef BPP
#undef GENERIC

#define GENERIC

#define BPP 32
#include "vnchextile.h"
#undef BPP
#undef GENERIC

static void send_framebuffer_update_hextile(VncState *vs, int x, int y, int w, int h)
{
    int i, j;
    int has_fg, has_bg;

    uint8_t *last_fg, *last_bg;

    vnc_framebuffer_update(vs, x, y, w, h, 5);

    last_fg = (uint8_t *) malloc(vs->depth);
    last_bg = (uint8_t *) malloc(vs->depth);

    has_fg = has_bg = 0;
    for (j = y; j < (y + h); j += 16) {
	for (i = x; i < (x + w); i += 16) {

            vs->send_hextile_tile(vs, i, j,

                                  MIN(16, x + w - i), MIN(16, y + h - j),

                                  last_bg, last_fg, &has_bg, &has_fg);

	}
    }

    free(last_fg);
    free(last_bg);

}

static void send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
{
	if (vs->has_hextile)
	    send_framebuffer_update_hextile(vs, x, y, w, h);
	else
	    send_framebuffer_update_raw(vs, x, y, w, h);
}

static void vnc_copy(DisplayState *ds, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
{
    int src, dst;

    uint8_t *src_row;
    uint8_t *dst_row;

    char *old_row;
    int y = 0;
    int pitch = ds->linesize;
    VncState *vs = ds->opaque;

    vnc_update_client(vs);

    if (dst_y > src_y) {
	y = h - 1;
	pitch = -pitch;
    }

    src = (ds->linesize * (src_y + y) + vs->depth * src_x);
    dst = (ds->linesize * (dst_y + y) + vs->depth * dst_x);

    src_row = ds->data + src;
    dst_row = ds->data + dst;
    old_row = vs->old_data + dst;

    for (y = 0; y < h; y++) {
	memmove(old_row, src_row, w * vs->depth);
	memmove(dst_row, src_row, w * vs->depth);
	src_row += pitch;
	dst_row += pitch;
	old_row += pitch;
    }

    vnc_write_u8(vs, 0);  /* msg id */
    vnc_write_u8(vs, 0);
    vnc_write_u16(vs, 1); /* number of rects */
    vnc_framebuffer_update(vs, dst_x, dst_y, w, h, 1);
    vnc_write_u16(vs, src_x);
    vnc_write_u16(vs, src_y);
    vnc_flush(vs);
}

static int find_dirty_height(VncState *vs, int y, int last_x, int x)
{
    int h;

    for (h = 1; h < (vs->height - y); h++) {
	int tmp_x;

	if (!vnc_get_bit(vs->dirty_row[y + h], last_x))

	    break;
	for (tmp_x = last_x; tmp_x < x; tmp_x++)

	    vnc_clear_bit(vs->dirty_row[y + h], tmp_x);

    }

    return h;
}

static void vnc_update_client(void *opaque)
{
    VncState *vs = opaque;

    if (vs->need_update && vs->csock != -1) {
	int y;

	uint8_t *row;

	char *old_row;

	uint32_t width_mask[VNC_DIRTY_WORDS];

	int n_rectangles;
	int saved_offset;
	int has_dirty = 0;

        vga_hw_update();

        vnc_set_bits(width_mask, (vs->width / 16), VNC_DIRTY_WORDS);

	/* Walk through the dirty map and eliminate tiles that
	   really aren't dirty */
	row = vs->ds->data;
	old_row = vs->old_data;

	for (y = 0; y < vs->height; y++) {

	    if (vnc_and_bits(vs->dirty_row[y], width_mask, VNC_DIRTY_WORDS)) {

		int x;

		uint8_t *ptr;
		char *old_ptr;

		ptr = row;

		old_ptr = (char*)old_row;

		for (x = 0; x < vs->ds->width; x += 16) {
		    if (memcmp(old_ptr, ptr, 16 * vs->depth) == 0) {

			vnc_clear_bit(vs->dirty_row[y], (x / 16));

		    } else {
			has_dirty = 1;
			memcpy(old_ptr, ptr, 16 * vs->depth);
		    }

		    ptr += 16 * vs->depth;
		    old_ptr += 16 * vs->depth;
		}
	    }

	    row += vs->ds->linesize;
	    old_row += vs->ds->linesize;
	}

	if (!has_dirty) {
	    qemu_mod_timer(vs->timer, qemu_get_clock(rt_clock) + VNC_REFRESH_INTERVAL);
	    return;
	}

	/* Count rectangles */
	n_rectangles = 0;
	vnc_write_u8(vs, 0);  /* msg id */
	vnc_write_u8(vs, 0);
	saved_offset = vs->output.offset;
	vnc_write_u16(vs, 0);

	for (y = 0; y < vs->height; y++) {
	    int x;
	    int last_x = -1;
	    for (x = 0; x < vs->width / 16; x++) {

		if (vnc_get_bit(vs->dirty_row[y], x)) {

		    if (last_x == -1) {
			last_x = x;
		    }

		    vnc_clear_bit(vs->dirty_row[y], x);

		} else {
		    if (last_x != -1) {
			int h = find_dirty_height(vs, y, last_x, x);
			send_framebuffer_update(vs, last_x * 16, y, (x - last_x) * 16, h);
			n_rectangles++;
		    }
		    last_x = -1;
		}
	    }
	    if (last_x != -1) {
		int h = find_dirty_height(vs, y, last_x, x);
		send_framebuffer_update(vs, last_x * 16, y, (x - last_x) * 16, h);
		n_rectangles++;
	    }
	}
	vs->output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
	vs->output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
	vnc_flush(vs);

    }

    if (vs->csock != -1) {
        qemu_mod_timer(vs->timer, qemu_get_clock(rt_clock) + VNC_REFRESH_INTERVAL);

    }

}

static int vnc_listen_poll(void *opaque)
{
    VncState *vs = opaque;
    if (vs->csock == -1)
	return 1;
    return 0;
}

static void buffer_reserve(Buffer *buffer, size_t len)
{
    if ((buffer->capacity - buffer->offset) < len) {
	buffer->capacity += (len + 1024);

	buffer->buffer = qemu_realloc(buffer->buffer, buffer->capacity);

	if (buffer->buffer == NULL) {
	    fprintf(stderr, "vnc: out of memory\n");
	    exit(1);
	}
    }
}

static int buffer_empty(Buffer *buffer)
{
    return buffer->offset == 0;
}

static uint8_t *buffer_end(Buffer *buffer)

{
    return buffer->buffer + buffer->offset;
}

static void buffer_reset(Buffer *buffer)
{
	buffer->offset = 0;
}

static void buffer_append(Buffer *buffer, const void *data, size_t len)
{
    memcpy(buffer->buffer + buffer->offset, data, len);
    buffer->offset += len;
}

static int vnc_client_io_error(VncState *vs, int ret, int last_errno)

{
    if (ret == 0 || ret == -1) {

        if (ret == -1) {
            switch (last_errno) {
                case EINTR:
                case EAGAIN:
#ifdef _WIN32
                case WSAEWOULDBLOCK:
#endif
                    return 0;
                default:
                    break;
            }
        }

	VNC_DEBUG("Closing down client sock %d %d\n", ret, ret < 0 ? last_errno : 0);

	qemu_set_fd_handler2(vs->csock, NULL, NULL, NULL, NULL);

	closesocket(vs->csock);

	vs->csock = -1;

	vs->ds->idle = 1;

	buffer_reset(&vs->input);
	buffer_reset(&vs->output);
	vs->need_update = 0;

#ifdef CONFIG_VNC_TLS

	if (vs->tls_session) {
	    gnutls_deinit(vs->tls_session);
	    vs->tls_session = NULL;
	}
	vs->wiremode = VNC_WIREMODE_CLEAR;
#endif /* CONFIG_VNC_TLS */

	return 0;
    }
    return ret;
}

static void vnc_client_error(VncState *vs)
{

    vnc_client_io_error(vs, -1, EINVAL);

}

static void vnc_client_write(void *opaque)
{

    long ret;

    VncState *vs = opaque;

#ifdef CONFIG_VNC_TLS

    if (vs->tls_session) {
	ret = gnutls_write(vs->tls_session, vs->output.buffer, vs->output.offset);
	if (ret < 0) {
	    if (ret == GNUTLS_E_AGAIN)
		errno = EAGAIN;
	    else
		errno = EIO;
	    ret = -1;
	}
    } else
#endif /* CONFIG_VNC_TLS */
	ret = send(vs->csock, vs->output.buffer, vs->output.offset, 0);

    ret = vnc_client_io_error(vs, ret, socket_error());

    if (!ret)
	return;

    memmove(vs->output.buffer, vs->output.buffer + ret, (vs->output.offset - ret));
    vs->output.offset -= ret;

    if (vs->output.offset == 0) {
	qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
    }
}

static void vnc_read_when(VncState *vs, VncReadEvent *func, size_t expecting)
{
    vs->read_handler = func;
    vs->read_handler_expect = expecting;
}

static void vnc_client_read(void *opaque)
{
    VncState *vs = opaque;

    long ret;

    buffer_reserve(&vs->input, 4096);

#ifdef CONFIG_VNC_TLS

    if (vs->tls_session) {
	ret = gnutls_read(vs->tls_session, buffer_end(&vs->input), 4096);
	if (ret < 0) {
	    if (ret == GNUTLS_E_AGAIN)
		errno = EAGAIN;
	    else
		errno = EIO;
	    ret = -1;
	}
    } else
#endif /* CONFIG_VNC_TLS */
	ret = recv(vs->csock, buffer_end(&vs->input), 4096, 0);

    ret = vnc_client_io_error(vs, ret, socket_error());

    if (!ret)
	return;

    vs->input.offset += ret;

    while (vs->read_handler && vs->input.offset >= vs->read_handler_expect) {
	size_t len = vs->read_handler_expect;
	int ret;

	ret = vs->read_handler(vs, vs->input.buffer, len);
	if (vs->csock == -1)
	    return;

	if (!ret) {
	    memmove(vs->input.buffer, vs->input.buffer + len, (vs->input.offset - len));
	    vs->input.offset -= len;
	} else {
	    vs->read_handler_expect = ret;
	}
    }
}

static void vnc_write(VncState *vs, const void *data, size_t len)
{
    buffer_reserve(&vs->output, len);

    if (buffer_empty(&vs->output)) {
	qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, vnc_client_write, vs);
    }

    buffer_append(&vs->output, data, len);
}

static void vnc_write_s32(VncState *vs, int32_t value)
{
    vnc_write_u32(vs, *(uint32_t *)&value);
}

static void vnc_write_u32(VncState *vs, uint32_t value)
{
    uint8_t buf[4];

    buf[0] = (value >> 24) & 0xFF;
    buf[1] = (value >> 16) & 0xFF;
    buf[2] = (value >>  8) & 0xFF;
    buf[3] = value & 0xFF;

    vnc_write(vs, buf, 4);
}

static void vnc_write_u16(VncState *vs, uint16_t value)
{