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/* See LICENSE file for copyright and license details. */
#include "common.h"
struct response {
union {
struct {
uint8_t status;
uint8_t length_of_reason; /* Only used in Failed, and not in Authenticate */
uint16_t protocol_major_version; /* Not in Authenticate */
uint16_t protocol_minor_version; /* Not in Authenticate */
uint16_t length_of_addition_data;
char additional_data[];
};
struct {
uint8_t __status__1;
uint8_t __length_of_reason__1;
uint16_t __protocol_major_version__1;
uint16_t __protocol_minor_version__1;
uint16_t __length_of_addition_data__1;
char reason[];
};
struct {
uint8_t __status__2;
uint8_t __length_of_reason__2;
uint16_t __protocol_major_version__2;
uint16_t __protocol_minor_version__2;
uint16_t __length_of_addition_data__2;
uint32_t release_number;
uint32_t resource_id_base;
uint32_t resource_id_mask;
uint32_t motion_buffer_size;
uint16_t length_of_vendor;
uint16_t maximum_request_length;
uint8_t number_of_roots;
uint8_t number_of_pixmap_formats;
uint8_t image_byte_order;
uint8_t bitmap_format_bit_order;
uint8_t bitmap_format_scanline_unit;
uint8_t bitmap_format_scanline_pad;
uint8_t min_keycode;
uint8_t max_keycode;
uint32_t __unused;
char vendor[];
};
};
};
int
libaxl_receive_handshake(LIBAXL_CONTEXT *restrict ctx, int *restrict majorp, int *restrict minorp, char **restrict reasonp, int flags)
{
LIBAXL_CONNECTION *conn = ctx->conn;
char *restrict inbuf, *new;
size_t i, j, k, n, t, len, vendor_len, out_off, in_off;
ssize_t r;
int read_stage = 0, saved_errno, status;
struct response *resp;
uint32_t xid_base, xid_mask;
struct libaxl_screen *screen;
struct libaxl_depth *depth;
#ifdef MSG_TRUNC
int flag_trunc;
#endif
#ifdef MSG_TRUNC
flags ^= flag_trunc = flags & MSG_TRUNC;
#endif
WLOCK_CONNECTION_RECV(conn);
inbuf = conn->in_buf;
n = offsetof(struct response, additional_data);
continue_read:
if (conn->in_buf_size < n) {
inbuf = liberror_realloc(inbuf, n);
if (!inbuf) {
WUNLOCK_CONNECTION_RECV(conn);
return LIBAXL_ERROR_SYSTEM;
}
conn->in_buf = inbuf;
conn->in_buf_size = n;
}
while (conn->in_progress < n) {
r = recv(conn->fd, &inbuf[conn->in_progress], n - conn->in_progress, flags);
if (r <= 0) {
liberror_save_backtrace(NULL);
if (!r) {
liberror_set_error("The connection to the display server has been closed",
"libaxl_receive_handshake", "libaxl", LIBAXL_ERROR_CONNECTION_CLOSED);
WUNLOCK_CONNECTION_RECV(conn);
return LIBAXL_ERROR_CONNECTION_CLOSED;
}
liberror_recv_failed(conn->fd, &inbuf[conn->in_progress], n - conn->in_progress, flags, "<display server>");
WUNLOCK_CONNECTION_RECV(conn);
return LIBAXL_ERROR_SYSTEM;
}
conn->in_progress += (size_t)r;
}
if (read_stage == 0) {
n += (size_t)ntohs(((struct response *)inbuf)->length_of_addition_data) * 4;
read_stage = 1;
goto continue_read;
}
conn->in_progress = 0;
#ifdef MSG_TRUNC
if (flag_trunc) {
WUNLOCK_CONNECTION_RECV(conn);
return 0;
}
#endif
t = conn->in_buf_size;
conn->in_buf_size = ctx->in_buf_size;
ctx->in_buf_size = t;
conn->in_buf = ctx->in_buf;
ctx->in_buf = inbuf;
WUNLOCK_CONNECTION_RECV(conn);
resp = (struct response *)inbuf;
if (majorp)
*majorp = (int)ntohs(resp->protocol_major_version);
if (minorp)
*minorp = (int)ntohs(resp->protocol_minor_version);
if (reasonp)
*reasonp = NULL;
status = (int)resp->status;
switch (resp->status) {
case LIBAXL_HANDSHAKE_FAILED:
len = (size_t)ntohs(resp->length_of_reason);
if (n < len + offsetof(struct response, reason))
goto invalid;
goto return_reason;
case LIBAXL_HANDSHAKE_AUTHENTICATE:
len = n - offsetof(struct response, reason);
return_reason:
if (reasonp) {
*reasonp = liberror_malloc(len + 1);
if (!*reasonp)
return LIBAXL_ERROR_SYSTEM;
memcpy(*reasonp, resp->reason, len);
(*reasonp)[len] = '\0';
}
break;
case LIBAXL_HANDSHAKE_SUCCESS:
xid_base = ntohl(resp->resource_id_base);
xid_mask = ntohl(resp->resource_id_mask);
if (xid_base & xid_mask || (xid_base | xid_mask) >> 29)
goto invalid;
conn->xid_base = xid_base;
for (conn->xid_shift = 0; !(xid_mask & 1); conn->xid_shift += 1)
xid_mask >>= 1;
conn->xid_max = xid_mask;
conn->info.vendor_release = ntohl(resp->release_number);
conn->info.min_keycode = resp->min_keycode;
conn->info.max_keycode = resp->max_keycode;
conn->info.image_byte_order = resp->image_byte_order;
conn->info.motion_buffer_size = ntohl(resp->motion_buffer_size);
conn->info.maximum_request_length = resp->maximum_request_length = ntohs(resp->maximum_request_length);
conn->info.bitmap_format_bit_order = resp->bitmap_format_bit_order;
conn->info.bitmap_format_scanline_unit = resp->bitmap_format_scanline_unit;
conn->info.bitmap_format_scanline_pad = resp->bitmap_format_scanline_pad;
/* These restricts are less restrictive than the protocol specifices,
* in case the they are modified later on */
if (!xid_mask ||
conn->xid_max + 1 < UINT16_C(1) << 18 ||
(conn->xid_max & (conn->xid_max + 1)) ||
resp->min_keycode < 8 ||
resp->image_byte_order > 1 ||
resp->maximum_request_length < 4096 ||
resp->bitmap_format_bit_order > 1 ||
resp->bitmap_format_scanline_unit % 8 ||
resp->bitmap_format_scanline_pad % 8 ||
resp->bitmap_format_scanline_unit > resp->bitmap_format_scanline_pad)
goto invalid;
vendor_len = ntohs(resp->length_of_vendor);
conn->info.nscreens = resp->number_of_roots;
conn->info.nformats = resp->number_of_pixmap_formats;
memmove(inbuf, resp->vendor, out_off = in_off = vendor_len);
inbuf[out_off++] = '\0';
out_off += (4 - out_off % 4) % 4;
in_off += (4 - in_off % 4) % 4;
in_off += offsetof(struct response, vendor);
t = out_off;
memmove(&inbuf[out_off], &inbuf[in_off], n - in_off);
out_off += n - in_off;
saved_errno = errno;
new = realloc(inbuf, out_off);
errno = saved_errno;
if (new)
inbuf = new;
conn->info_buf = inbuf;
conn->info.vendor = inbuf;
conn->info.formats = (void *)&inbuf[t];
conn->info.screens = screen = (void *)&inbuf[t + conn->info.nformats * 8];
if ((size_t)conn->info.default_screen_number < conn->info.nscreens) {
conn->info.default_screen = conn->info.screens;
for (i = 0; i < (size_t)conn->info.default_screen_number; i++)
conn->info.default_screen = libaxl_next_screen(conn->info.default_screen);
} else {
conn->info.default_screen = NULL;
}
for (i = 0; i < (size_t)conn->info.nscreens; i++) {
screen->root = ntohl(screen->root);
screen->default_colormap = ntohl(screen->default_colormap);
screen->white_pixel = ntohl(screen->white_pixel);
screen->black_pixel = ntohl(screen->black_pixel);
screen->current_input_masks = ntohl(screen->current_input_masks);
screen->width_in_pixels = ntohs(screen->width_in_pixels);
screen->height_in_pixels = ntohs(screen->height_in_pixels);
screen->width_in_millimeters = ntohs(screen->width_in_millimeters);
screen->height_in_millimeters = ntohs(screen->height_in_millimeters);
screen->min_installed_maps = ntohs(screen->min_installed_maps);
screen->max_installed_maps = ntohs(screen->max_installed_maps);
screen->root_visual = ntohs(screen->root_visual);
depth = screen->allowed_depths;
for (j = 0; j < (size_t)screen->number_of_allowed_depths; j++) {
depth->number_of_visuals = ntohs(depth->number_of_visuals);
for (k = 0; k < (size_t)depth->number_of_visuals; k++) {
depth->visuals[k].visual_id = ntohl(depth->visuals[k].visual_id);
depth->visuals[k].colormap_entries = ntohs(depth->visuals[k].colormap_entries);
depth->visuals[k].red_mask = ntohl(depth->visuals[k].red_mask);
depth->visuals[k].green_mask = ntohl(depth->visuals[k].green_mask);
depth->visuals[k].blue_mask = ntohl(depth->visuals[k].blue_mask);
}
depth = (void *)(uintptr_t)&depth->visuals[depth->number_of_visuals];
}
screen = (void *)(uintptr_t)depth;
}
ctx->in_buf_size = 0;
ctx->in_buf = NULL;
break;
default:
invalid:
liberror_set_error("Invalid handshake response received from the display server",
"libaxl_receive_handshake", "libaxl", LIBAXL_ERROR_INVALID_HANDSHAKE_RESPONSE);
errno = EBADMSG;
return LIBAXL_ERROR_INVALID_HANDSHAKE_RESPONSE;
}
return status;
}
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