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glibc/sysdeps/unix/sysv/linux/netlink_assert_response.c
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/* Check recvmsg results for netlink sockets. | |
Copyright (C) 2015-2016 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 | |
<http://www.gnu.org/licenses/>. */ | |
#include <errno.h> | |
#include <fcntl.h> | |
#include <stdio.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 | |
internal_function | |
__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", | |
error_code, fd); | |
else | |
__snprintf (message, sizeof (message), | |
"Unexpected error %d on netlink descriptor %d" | |
" (address family %d)", | |
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", | |
result, fd); | |
else | |
__snprintf (message, sizeof (message), | |
"Unexpected netlink response of size %zd" | |
" on descriptor %d (address family %d)", | |
result, fd, family); | |
__libc_fatal (message); | |
} | |
} | |
libc_hidden_def (__netlink_assert_response) |