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https://sourceware.org/git/glibc.git
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432 lines
9.8 KiB
C
432 lines
9.8 KiB
C
/* Determine protocol families for which interfaces exist. Linux version.
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Copyright (C) 2003, 2006-2008, 2010, 2011 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <errno.h>
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#include <ifaddrs.h>
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#include <netdb.h>
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#include <stddef.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <sys/socket.h>
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#include <asm/types.h>
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#include <linux/netlink.h>
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#include <linux/rtnetlink.h>
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#include <not-cancel.h>
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#include <kernel-features.h>
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#include <bits/libc-lock.h>
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#include <atomic.h>
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#include <nscd/nscd-client.h>
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#ifndef IFA_F_HOMEADDRESS
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# define IFA_F_HOMEADDRESS 0
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#endif
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#ifndef IFA_F_OPTIMISTIC
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# define IFA_F_OPTIMISTIC 0
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#endif
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struct cached_data
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{
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uint32_t timestamp;
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uint32_t usecnt;
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bool seen_ipv4;
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bool seen_ipv6;
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size_t in6ailen;
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struct in6addrinfo in6ai[0];
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};
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static struct cached_data noai6ai_cached =
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{
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.usecnt = 1, /* Make sure we never try to delete this entry. */
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.in6ailen = 0
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};
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static struct cached_data *cache;
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__libc_lock_define_initialized (static, lock);
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#ifdef IS_IN_nscd
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static uint32_t nl_timestamp;
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uint32_t
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__bump_nl_timestamp (void)
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{
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if (atomic_increment_val (&nl_timestamp) == 0)
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atomic_increment (&nl_timestamp);
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return nl_timestamp;
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}
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#endif
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static struct cached_data *
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make_request (int fd, pid_t pid)
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{
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struct req
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{
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struct nlmsghdr nlh;
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struct rtgenmsg g;
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/* struct rtgenmsg consists of a single byte. This means there
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are three bytes of padding included in the REQ definition.
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We make them explicit here. */
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char pad[3];
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} req;
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struct sockaddr_nl nladdr;
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req.nlh.nlmsg_len = sizeof (req);
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req.nlh.nlmsg_type = RTM_GETADDR;
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req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
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req.nlh.nlmsg_pid = 0;
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req.nlh.nlmsg_seq = time (NULL);
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req.g.rtgen_family = AF_UNSPEC;
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assert (sizeof (req) - offsetof (struct req, pad) == 3);
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memset (req.pad, '\0', sizeof (req.pad));
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memset (&nladdr, '\0', sizeof (nladdr));
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nladdr.nl_family = AF_NETLINK;
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#ifdef PAGE_SIZE
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/* Help the compiler optimize out the malloc call if PAGE_SIZE
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is constant and smaller or equal to PTHREAD_STACK_MIN/4. */
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const size_t buf_size = PAGE_SIZE;
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#else
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const size_t buf_size = __getpagesize ();
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#endif
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bool use_malloc = false;
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char *buf;
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if (__libc_use_alloca (buf_size))
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buf = alloca (buf_size);
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else
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{
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buf = malloc (buf_size);
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if (buf != NULL)
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use_malloc = true;
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else
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goto out_fail;
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}
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struct iovec iov = { buf, buf_size };
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if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0,
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(struct sockaddr *) &nladdr,
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sizeof (nladdr))) < 0)
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goto out_fail;
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bool done = false;
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struct in6ailist
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{
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struct in6addrinfo info;
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struct in6ailist *next;
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} *in6ailist = NULL;
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size_t in6ailistlen = 0;
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bool seen_ipv4 = false;
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bool seen_ipv6 = false;
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do
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{
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struct msghdr msg =
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{
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(void *) &nladdr, sizeof (nladdr),
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&iov, 1,
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NULL, 0,
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0
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};
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ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0));
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if (read_len < 0)
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goto out_fail;
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if (msg.msg_flags & MSG_TRUNC)
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goto out_fail;
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struct nlmsghdr *nlmh;
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for (nlmh = (struct nlmsghdr *) buf;
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NLMSG_OK (nlmh, (size_t) read_len);
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nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len))
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{
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if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid
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|| nlmh->nlmsg_seq != req.nlh.nlmsg_seq)
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continue;
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if (nlmh->nlmsg_type == RTM_NEWADDR)
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{
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struct ifaddrmsg *ifam = (struct ifaddrmsg *) NLMSG_DATA (nlmh);
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struct rtattr *rta = IFA_RTA (ifam);
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size_t len = nlmh->nlmsg_len - NLMSG_LENGTH (sizeof (*ifam));
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if (ifam->ifa_family != AF_INET
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&& ifam->ifa_family != AF_INET6)
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continue;
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const void *local = NULL;
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const void *address = NULL;
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while (RTA_OK (rta, len))
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{
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switch (rta->rta_type)
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{
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case IFA_LOCAL:
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local = RTA_DATA (rta);
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break;
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case IFA_ADDRESS:
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address = RTA_DATA (rta);
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goto out;
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}
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rta = RTA_NEXT (rta, len);
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}
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if (local != NULL)
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{
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address = local;
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out:
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if (ifam->ifa_family == AF_INET)
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{
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if (*(const in_addr_t *) address
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!= htonl (INADDR_LOOPBACK))
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seen_ipv4 = true;
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}
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else
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{
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if (!IN6_IS_ADDR_LOOPBACK (address))
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seen_ipv6 = true;
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}
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}
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struct in6ailist *newp = alloca (sizeof (*newp));
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newp->info.flags = (((ifam->ifa_flags
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& (IFA_F_DEPRECATED
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| IFA_F_OPTIMISTIC))
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? in6ai_deprecated : 0)
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| ((ifam->ifa_flags
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& IFA_F_HOMEADDRESS)
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? in6ai_homeaddress : 0));
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newp->info.prefixlen = ifam->ifa_prefixlen;
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newp->info.index = ifam->ifa_index;
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if (ifam->ifa_family == AF_INET)
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{
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newp->info.addr[0] = 0;
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newp->info.addr[1] = 0;
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newp->info.addr[2] = htonl (0xffff);
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newp->info.addr[3] = *(const in_addr_t *) address;
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}
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else
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memcpy (newp->info.addr, address, sizeof (newp->info.addr));
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newp->next = in6ailist;
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in6ailist = newp;
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++in6ailistlen;
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}
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else if (nlmh->nlmsg_type == NLMSG_DONE)
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/* We found the end, leave the loop. */
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done = true;
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}
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}
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while (! done);
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struct cached_data *result;
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if (seen_ipv6 && in6ailist != NULL)
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{
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result = malloc (sizeof (*result)
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+ in6ailistlen * sizeof (struct in6addrinfo));
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if (result == NULL)
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goto out_fail;
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#ifdef IS_IN_nscd
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result->timestamp = nl_timestamp;
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#else
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result->timestamp = __nscd_get_nl_timestamp ();
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#endif
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result->usecnt = 2;
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result->seen_ipv4 = seen_ipv4;
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result->seen_ipv6 = true;
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result->in6ailen = in6ailistlen;
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do
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{
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result->in6ai[--in6ailistlen] = in6ailist->info;
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in6ailist = in6ailist->next;
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}
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while (in6ailist != NULL);
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}
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else
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{
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atomic_add (&noai6ai_cached.usecnt, 2);
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noai6ai_cached.seen_ipv4 = seen_ipv4;
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noai6ai_cached.seen_ipv6 = seen_ipv6;
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result = &noai6ai_cached;
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}
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if (use_malloc)
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free (buf);
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return result;
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out_fail:
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if (use_malloc)
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free (buf);
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return NULL;
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}
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/* We don't know if we have NETLINK support compiled into our
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Kernel. */
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#if __ASSUME_NETLINK_SUPPORT == 0
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/* Define in ifaddrs.h. */
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extern int __no_netlink_support attribute_hidden;
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#else
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# define __no_netlink_support 0
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#endif
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void
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attribute_hidden
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__check_pf (bool *seen_ipv4, bool *seen_ipv6,
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struct in6addrinfo **in6ai, size_t *in6ailen)
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{
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*in6ai = NULL;
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*in6ailen = 0;
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if (! __no_netlink_support)
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{
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struct cached_data *olddata = NULL;
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struct cached_data *data = NULL;
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__libc_lock_lock (lock);
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#ifdef IS_IN_nscd
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# define cache_valid() nl_timestamp != 0 && cache->timestamp == nl_timestamp
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#else
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# define cache_valid() \
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({ uint32_t val = __nscd_get_nl_timestamp (); \
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val != 0 && cache->timestamp == val; })
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#endif
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if (cache != NULL && cache_valid ())
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{
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data = cache;
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atomic_increment (&cache->usecnt);
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}
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else
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{
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int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
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if (__builtin_expect (fd >= 0, 1))
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{
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struct sockaddr_nl nladdr;
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memset (&nladdr, '\0', sizeof (nladdr));
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nladdr.nl_family = AF_NETLINK;
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socklen_t addr_len = sizeof (nladdr);
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if(__bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0
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&& __getsockname (fd, (struct sockaddr *) &nladdr,
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&addr_len) == 0)
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data = make_request (fd, nladdr.nl_pid);
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close_not_cancel_no_status (fd);
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}
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if (data != NULL)
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{
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olddata = cache;
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cache = data;
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}
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}
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__libc_lock_unlock (lock);
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if (data != NULL)
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{
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/* It worked. */
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*seen_ipv4 = data->seen_ipv4;
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*seen_ipv6 = data->seen_ipv6;
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*in6ailen = data->in6ailen;
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*in6ai = data->in6ai;
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if (olddata != NULL && olddata->usecnt > 0
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&& atomic_add_zero (&olddata->usecnt, -1))
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free (olddata);
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return;
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}
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#if __ASSUME_NETLINK_SUPPORT == 0
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/* Remember that there is no netlink support. */
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__no_netlink_support = 1;
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#else
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/* We cannot determine what interfaces are available. Be
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pessimistic. */
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*seen_ipv4 = true;
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*seen_ipv6 = true;
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#endif
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}
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#if __ASSUME_NETLINK_SUPPORT == 0
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/* No netlink. Get the interface list via getifaddrs. */
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struct ifaddrs *ifa = NULL;
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if (getifaddrs (&ifa) != 0)
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{
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/* We cannot determine what interfaces are available. Be
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pessimistic. */
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*seen_ipv4 = true;
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*seen_ipv6 = true;
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return;
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}
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struct ifaddrs *runp;
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for (runp = ifa; runp != NULL; runp = runp->ifa_next)
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if (runp->ifa_addr != NULL)
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{
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if (runp->ifa_addr->sa_family == PF_INET)
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*seen_ipv4 = true;
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else if (runp->ifa_addr->sa_family == PF_INET6)
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*seen_ipv6 = true;
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}
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(void) freeifaddrs (ifa);
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#endif
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}
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void
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__free_in6ai (struct in6addrinfo *ai)
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{
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if (ai != NULL)
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{
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struct cached_data *data =
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(struct cached_data *) ((char *) ai
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- offsetof (struct cached_data, in6ai));
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if (atomic_add_zero (&data->usecnt, -1))
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{
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__libc_lock_lock (lock);
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if (data->usecnt == 0)
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/* Still unused. */
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free (data);
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__libc_lock_unlock (lock);
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}
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}
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}
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