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glibc/sysdeps/unix/sysv/linux/check_pf.c
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/* Determine protocol families for which interfaces exist. Linux version. | |
Copyright (C) 2003, 2006, 2007 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, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#include <assert.h> | |
#include <errno.h> | |
#include <ifaddrs.h> | |
#include <netdb.h> | |
#include <stddef.h> | |
#include <string.h> | |
#include <time.h> | |
#include <unistd.h> | |
#include <sys/socket.h> | |
#include <asm/types.h> | |
#include <linux/netlink.h> | |
#include <linux/rtnetlink.h> | |
#include <not-cancel.h> | |
#include <kernel-features.h> | |
#ifndef IFA_F_TEMPORARY | |
# define IFA_F_TEMPORARY IFA_F_SECONDARY | |
#endif | |
#ifndef IFA_F_HOMEADDRESS | |
# define IFA_F_HOMEADDRESS 0 | |
#endif | |
static int | |
make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6, | |
struct in6addrinfo **in6ai, size_t *in6ailen) | |
{ | |
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; | |
struct sockaddr_nl nladdr; | |
req.nlh.nlmsg_len = sizeof (req); | |
req.nlh.nlmsg_type = RTM_GETADDR; | |
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; | |
*seen_ipv4 = false; | |
*seen_ipv6 = false; | |
bool done = false; | |
struct in6ailist | |
{ | |
struct in6addrinfo info; | |
struct in6ailist *next; | |
} *in6ailist = NULL; | |
size_t in6ailistlen = 0; | |
do | |
{ | |
struct msghdr msg = | |
{ | |
(void *) &nladdr, sizeof (nladdr), | |
&iov, 1, | |
NULL, 0, | |
0 | |
}; | |
ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0)); | |
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_NEWADDR) | |
{ | |
struct ifaddrmsg *ifam = (struct ifaddrmsg *) NLMSG_DATA (nlmh); | |
switch (ifam->ifa_family) | |
{ | |
case AF_INET: | |
*seen_ipv4 = true; | |
break; | |
case AF_INET6: | |
*seen_ipv6 = true; | |
if (ifam->ifa_flags & (IFA_F_DEPRECATED | |
| IFA_F_TEMPORARY | |
| IFA_F_HOMEADDRESS)) | |
{ | |
struct rtattr *rta = IFA_RTA (ifam); | |
size_t len = (nlmh->nlmsg_len | |
- NLMSG_LENGTH (sizeof (*ifam))); | |
void *local = NULL; | |
void *address = NULL; | |
while (RTA_OK (rta, len)) | |
{ | |
switch (rta->rta_type) | |
{ | |
case IFA_LOCAL: | |
local = RTA_DATA (rta); | |
break; | |
case IFA_ADDRESS: | |
address = RTA_DATA (rta); | |
break; | |
} | |
rta = RTA_NEXT (rta, len); | |
} | |
struct in6ailist *newp = alloca (sizeof (*newp)); | |
newp->info.flags = (((ifam->ifa_flags & IFA_F_DEPRECATED) | |
? in6ai_deprecated : 0) | |
| ((ifam->ifa_flags | |
& IFA_F_TEMPORARY) | |
? in6ai_temporary : 0) | |
| ((ifam->ifa_flags | |
& IFA_F_HOMEADDRESS) | |
? in6ai_homeaddress : 0)); | |
memcpy (newp->info.addr, address ?: local, | |
sizeof (newp->info.addr)); | |
newp->next = in6ailist; | |
in6ailist = newp; | |
++in6ailistlen; | |
} | |
break; | |
default: | |
/* Ignore. */ | |
break; | |
} | |
} | |
else if (nlmh->nlmsg_type == NLMSG_DONE) | |
/* We found the end, leave the loop. */ | |
done = true; | |
} | |
} | |
while (! done); | |
close_not_cancel_no_status (fd); | |
if (in6ailist != NULL) | |
{ | |
*in6ai = malloc (in6ailistlen * sizeof (**in6ai)); | |
if (*in6ai == NULL) | |
goto out_fail; | |
*in6ailen = in6ailistlen; | |
do | |
{ | |
(*in6ai)[--in6ailistlen] = in6ailist->info; | |
in6ailist = in6ailist->next; | |
} | |
while (in6ailist != NULL); | |
} | |
if (use_malloc) | |
free (buf); | |
return 0; | |
out_fail: | |
if (use_malloc) | |
free (buf); | |
return -1; | |
} | |
/* We don't know if we have NETLINK support compiled in in our | |
Kernel. */ | |
#if __ASSUME_NETLINK_SUPPORT == 0 | |
/* Define in ifaddrs.h. */ | |
extern int __no_netlink_support attribute_hidden; | |
#else | |
# define __no_netlink_support 0 | |
#endif | |
void | |
attribute_hidden | |
__check_pf (bool *seen_ipv4, bool *seen_ipv6, | |
struct in6addrinfo **in6ai, size_t *in6ailen) | |
{ | |
*in6ai = NULL; | |
*in6ailen = 0; | |
if (! __no_netlink_support) | |
{ | |
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 | |
&& make_request (fd, nladdr.nl_pid, seen_ipv4, seen_ipv6, | |
in6ai, in6ailen) == 0) | |
/* It worked. */ | |
return; | |
if (fd >= 0) | |
__close (fd); | |
#if __ASSUME_NETLINK_SUPPORT == 0 | |
/* Remember that there is no netlink support. */ | |
__no_netlink_support = 1; | |
#else | |
/* We cannot determine what interfaces are available. Be | |
pessimistic. */ | |
*seen_ipv4 = true; | |
*seen_ipv6 = true; | |
#endif | |
} | |
#if __ASSUME_NETLINK_SUPPORT == 0 | |
/* No netlink. Get the interface list via getifaddrs. */ | |
struct ifaddrs *ifa = NULL; | |
if (getifaddrs (&ifa) != 0) | |
{ | |
/* We cannot determine what interfaces are available. Be | |
pessimistic. */ | |
*seen_ipv4 = true; | |
*seen_ipv6 = true; | |
return; | |
} | |
struct ifaddrs *runp; | |
for (runp = ifa; runp != NULL; runp = runp->ifa_next) | |
if (runp->ifa_addr->sa_family == PF_INET) | |
*seen_ipv4 = true; | |
else if (runp->ifa_addr->sa_family == PF_INET6) | |
*seen_ipv6 = true; | |
(void) freeifaddrs (ifa); | |
#endif | |
} |