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/* Check recvmsg results for netlink sockets.
Copyright (C) 2015-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdbool.h>
#include <sys/socket.h>
#include "netlinkaccess.h"
static int
get_address_family (int fd)
{
struct sockaddr_storage sa;
socklen_t sa_len = sizeof (sa);
if (__getsockname (fd, (struct sockaddr *) &sa, &sa_len) < 0)
return -1;
/* Check that the socket family number is preserved despite in-band
signaling. */
_Static_assert (sizeof (sa.ss_family) < sizeof (int), "address family size");
_Static_assert (0 < (__typeof__ (sa.ss_family)) -1,
"address family unsigned");
return sa.ss_family;
}
void
__netlink_assert_response (int fd, ssize_t result)
{
if (result < 0)
{
/* Check if the error is unexpected. */
bool terminate = false;
int error_code = errno;
int family = get_address_family (fd);
if (family != AF_NETLINK)
/* If the address family does not match (or getsockname
failed), report the original error. */
terminate = true;
else if (error_code == EBADF
|| error_code == ENOTCONN
|| error_code == ENOTSOCK
|| error_code == ECONNREFUSED)
/* These errors indicate that the descriptor is not a
connected socket. */
terminate = true;
else if (error_code == EAGAIN || error_code == EWOULDBLOCK)
{
/* The kernel might return EAGAIN for other reasons than a
non-blocking socket. But if the socket is not blocking,
it is not ours, so report the error. */
int mode = __fcntl (fd, F_GETFL, 0);
if (mode < 0 || (mode & O_NONBLOCK) != 0)
terminate = true;
}
if (terminate)
{
char message[200];
if (family < 0)
__snprintf (message, sizeof (message),
"Unexpected error %d on netlink descriptor %d.\n",
error_code, fd);
else
__snprintf (message, sizeof (message),
"Unexpected error %d on netlink descriptor %d"
" (address family %d).\n",
error_code, fd, family);
__libc_fatal (message);
}
else
/* Restore orignal errno value. */
__set_errno (error_code);
}
else if (result < sizeof (struct nlmsghdr))
{
char message[200];
int family = get_address_family (fd);
if (family < 0)
__snprintf (message, sizeof (message),
"Unexpected netlink response of size %zd"
" on descriptor %d\n",
result, fd);
else
__snprintf (message, sizeof (message),
"Unexpected netlink response of size %zd"
" on descriptor %d (address family %d)\n",
result, fd, family);
__libc_fatal (message);
}
}
libc_hidden_def (__netlink_assert_response)
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