/* See LICENSE file for copyright and license details. */
#include "common.h"
struct response {
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 */
union {
struct {
uint16_t length_of_addition_data;
char additional_data[];
};
struct {
uint16_t __length_of_addition_data__1;
char reason[];
};
struct {
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 n, t, len, vendor_len, out_off, in_off;
ssize_t r;
int read_stage = 0, saved_errno;
struct response *resp;
#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);
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;
}
continue_read:
while (conn->in_progress < n) {
r = recv(conn->fd, &inbuf[conn->in_progress], n - conn->in_progress, flags);
if (r <= 0) {
WUNLOCK_CONNECTION_RECV(conn);
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);
return LIBAXL_ERROR_CONNECTION_CLOSED;
}
liberror_recv_failed(conn->fd, &inbuf[conn->in_progress], n - conn->in_progress, flags, "<display server>");
return LIBAXL_ERROR_SYSTEM;
}
conn->in_progress += (size_t)r;
}
if (read_stage == 0) {
n += (size_t)((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)resp->protocol_major_version;
if (minorp)
*minorp = (int)resp->protocol_minor_version;
if (reasonp)
*reasonp = NULL;
switch (resp->status) {
case LIBAXL_HANDSHAKE_FAILED:
len = (size_t)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:
if (resp->resource_id_base & resp->resource_id_mask ||
(resp->resource_id_base | resp->resource_id_mask) >> 29)
goto invalid;
conn->xid_base = resp->resource_id_base;
for (conn->xid_shift = 0; !(resp->resource_id_mask & 1); conn->xid_shift += 1)
resp->resource_id_mask >>= 1;
conn->xid_max = resp->resource_id_mask;
conn->info.vendor_release = 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 = resp->motion_buffer_size;
conn->info.maximum_request_length = 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 (resp->resource_id_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 = 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 = (void *)&inbuf[t + conn->info.nformats * 8];
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 (int)resp->status;
}
