277 lines
6.7 KiB
C
277 lines
6.7 KiB
C
/* Determine protocol families for which interfaces exist. Linux version.
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Copyright (C) 2003, 2006 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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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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#ifndef IFA_F_TEMPORARY
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# define IFA_F_TEMPORARY IFA_F_SECONDARY
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#endif
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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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static int
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make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
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struct in6addrinfo **in6ai, size_t *in6ailen)
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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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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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return -1;
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*seen_ipv4 = false;
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*seen_ipv6 = false;
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bool done = false;
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char buf[4096];
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struct iovec iov = { buf, sizeof (buf) };
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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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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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return -1;
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if (msg.msg_flags & MSG_TRUNC)
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return -1;
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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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switch (ifam->ifa_family)
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{
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case AF_INET:
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*seen_ipv4 = true;
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break;
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case AF_INET6:
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*seen_ipv6 = true;
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if (ifam->ifa_flags & (IFA_F_DEPRECATED
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| IFA_F_TEMPORARY
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| IFA_F_HOMEADDRESS))
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{
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struct rtattr *rta = IFA_RTA (ifam);
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size_t len = (nlmh->nlmsg_len
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- NLMSG_LENGTH (sizeof (*ifam)));
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void *local = NULL;
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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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break;
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}
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rta = RTA_NEXT (rta, len);
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}
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struct in6ailist *newp = alloca (sizeof (*newp));
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newp->info.flags = (((ifam->ifa_flags & IFA_F_DEPRECATED)
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? in6ai_deprecated : 0)
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| ((ifam->ifa_flags
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& IFA_F_TEMPORARY)
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? in6ai_temporary : 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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memcpy (newp->info.addr, address ?: local,
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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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break;
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default:
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/* Ignore. */
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break;
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}
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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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close_not_cancel_no_status (fd);
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if (in6ailist != NULL)
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{
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*in6ai = malloc (in6ailistlen * sizeof (**in6ai));
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if (*in6ai == NULL)
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return -1;
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*in6ailen = in6ailistlen;
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do
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{
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(*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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return 0;
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}
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/* We don't know if we have NETLINK support compiled in in 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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int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
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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 (fd >= 0
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&& __bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0
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&& __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) == 0
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&& make_request (fd, nladdr.nl_pid, seen_ipv4, seen_ipv6,
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in6ai, in6ailen) == 0)
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/* It worked. */
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return;
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if (fd >= 0)
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__close (fd);
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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->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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(void) freeifaddrs (ifa);
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#endif
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}
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