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glibc/sysdeps/unix/sysv/linux/check_native.c
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/* Determine whether interfaces use native transport. Linux version. | |
Copyright (C) 2007-2016 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 <assert.h> | |
#include <errno.h> | |
#include <ifaddrs.h> | |
#include <stddef.h> | |
#include <stdint.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <time.h> | |
#include <unistd.h> | |
#include <net/if.h> | |
#include <net/if_arp.h> | |
#include <sys/ioctl.h> | |
#include <asm/types.h> | |
#include <linux/netlink.h> | |
#include <linux/rtnetlink.h> | |
#include <not-cancel.h> | |
#include "netlinkaccess.h" | |
void | |
__check_native (uint32_t a1_index, int *a1_native, | |
uint32_t a2_index, int *a2_native) | |
{ | |
int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE); | |
struct sockaddr_nl nladdr; | |
memset (&nladdr, '\0', sizeof (nladdr)); | |
nladdr.nl_family = AF_NETLINK; | |
socklen_t addr_len = sizeof (nladdr); | |
if (fd < 0 | |
|| __bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) != 0 | |
|| __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) != 0) | |
return; | |
pid_t pid = nladdr.nl_pid; | |
struct req | |
{ | |
struct nlmsghdr nlh; | |
struct rtgenmsg g; | |
/* struct rtgenmsg consists of a single byte. This means there | |
are three bytes of padding included in the REQ definition. | |
We make them explicit here. */ | |
char pad[3]; | |
} req; | |
req.nlh.nlmsg_len = sizeof (req); | |
req.nlh.nlmsg_type = RTM_GETLINK; | |
req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST; | |
req.nlh.nlmsg_pid = 0; | |
req.nlh.nlmsg_seq = time (NULL); | |
req.g.rtgen_family = AF_UNSPEC; | |
assert (sizeof (req) - offsetof (struct req, pad) == 3); | |
memset (req.pad, '\0', sizeof (req.pad)); | |
memset (&nladdr, '\0', sizeof (nladdr)); | |
nladdr.nl_family = AF_NETLINK; | |
#ifdef PAGE_SIZE | |
/* Help the compiler optimize out the malloc call if PAGE_SIZE | |
is constant and smaller or equal to PTHREAD_STACK_MIN/4. */ | |
const size_t buf_size = PAGE_SIZE; | |
#else | |
const size_t buf_size = __getpagesize (); | |
#endif | |
bool use_malloc = false; | |
char *buf; | |
if (__libc_use_alloca (buf_size)) | |
buf = alloca (buf_size); | |
else | |
{ | |
buf = malloc (buf_size); | |
if (buf != NULL) | |
use_malloc = true; | |
else | |
goto out_fail; | |
} | |
struct iovec iov = { buf, buf_size }; | |
if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0, | |
(struct sockaddr *) &nladdr, | |
sizeof (nladdr))) < 0) | |
goto out_fail; | |
bool done = false; | |
do | |
{ | |
struct msghdr msg = | |
{ | |
(void *) &nladdr, sizeof (nladdr), | |
&iov, 1, | |
NULL, 0, | |
0 | |
}; | |
ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0)); | |
__netlink_assert_response (fd, read_len); | |
if (read_len < 0) | |
goto out_fail; | |
if (msg.msg_flags & MSG_TRUNC) | |
goto out_fail; | |
struct nlmsghdr *nlmh; | |
for (nlmh = (struct nlmsghdr *) buf; | |
NLMSG_OK (nlmh, (size_t) read_len); | |
nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len)) | |
{ | |
if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid | |
|| nlmh->nlmsg_seq != req.nlh.nlmsg_seq) | |
continue; | |
if (nlmh->nlmsg_type == RTM_NEWLINK) | |
{ | |
struct ifinfomsg *ifim = (struct ifinfomsg *) NLMSG_DATA (nlmh); | |
int native = (ifim->ifi_type != ARPHRD_TUNNEL6 | |
&& ifim->ifi_type != ARPHRD_TUNNEL | |
&& ifim->ifi_type != ARPHRD_SIT); | |
if (a1_index == ifim->ifi_index) | |
{ | |
*a1_native = native; | |
a1_index = 0xffffffffu; | |
} | |
if (a2_index == ifim->ifi_index) | |
{ | |
*a2_native = native; | |
a2_index = 0xffffffffu; | |
} | |
if (a1_index == 0xffffffffu | |
&& a2_index == 0xffffffffu) | |
goto out; | |
} | |
else if (nlmh->nlmsg_type == NLMSG_DONE) | |
/* We found the end, leave the loop. */ | |
done = true; | |
} | |
} | |
while (! done); | |
out: | |
close_not_cancel_no_status (fd); | |
return; | |
out_fail: | |
if (use_malloc) | |
free (buf); | |
} |