New utility: ifwatchd.
Monitors the routing socket for address changes of autonomous (kernel only) interfaces (like PPPoE) and runs up/down scripts similar to what pppd does for its interfaces.
This commit is contained in:
martin
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# $NetBSD: Makefile,v 1.1 2001/11/19 09:43:03 martin Exp $
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PROG=ifwatchd
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MAN=ifwatchd.8
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.include <bsd.prog.mk>
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.\" Copyright (C) 2001 by Martin Husemann
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS
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.\" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT,
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.\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd September 2, 2001
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.Os
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.Dt IFWATCHD 8
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.Sh NAME
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.Nm ifwatchd
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.Nd watch for adresses added to or deleted from interfaces and call up/down scripts for them
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.Sh SYNOPSIS
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.Nm
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.Op Fl h
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.Op Fl v
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.Op Fl d Ar down-script
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.Op Fl u Ar up-script
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.Ar ifname(s)
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.Pp
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.Sh DESCRIPTION
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.Nm Ifwatchd
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is used to monitor dynamic interfaces (for example PPP interfaces) for address
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changes. Sometimes this interfaces are acompanied by a daemon program, which
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can take care of running any necesary scripts (like pppd or isdnd), but
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sometimes the interfaces run completely autonomus (like pppoe).
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.Pp
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.Nm Ifwatchd
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provides a generic way to watch this type of changes. It works by monitoring
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the routing socket and interpreting
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.Ql RTM_NEWADDR
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.Pq address added
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and
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.Ql RTM_DELADDR
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.Pq address deleted
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messages. It does not need special privileges to do this. The scripts called
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for up or down events are run with the same user id as
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.Nm
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is run.
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.Pp
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The following options are available:
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.Bl -tag -width indent
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.It Fl h
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Show the synopsis.
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.It Fl v
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Output verbose progress messages and flag errors ignored during normal
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operation.
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.It Fl u Ar up-script
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Specify the command to invoke on
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.Dq interface up
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events (or: addition of an address to an interface).
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.It Fl d Ar down-script
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Specify the command to invoke on
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.Dq interface down
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events (or: deletion of an address from an interface).
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.It ifname(s)
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The name of the interface to watch. Multiple interfaces may be specified.
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Events for other interfaces are ignored.
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.El
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.Sh EXAMPLES
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Note: you may be able to run
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.Nm
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from
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.Pa /etc/ifconfig.*
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files via the
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.Em !
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shell command syntax, but only if your /usr partition is already mounted
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(i.e. you either do not have a separate /usr partition or you have its
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mount point included in the critical_filesystems_beforenet /etc/rc.conf
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variable.)
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.Bd -literal
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# ifwatchd -u /etc/ppp/ip-up -d /etc/ppp/ip-down pppoe0
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.Ed
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.Sh PARAMETERS PASSED TO SCRIPTS
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The invoked scripts get three parameters passed:
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.Bl -tag -width indent
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.It Ar ifname
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The name of the interface this change is for (this allows to share the same
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script for multiple interfaces wathed and dispatching on the interface name
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in the script).
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.It Ar up/down
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Verbatim
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.Em up
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or
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.Em down ,
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which allows for the sharing of up and down scripts.
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.It Ar address
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the new address if this is an up event, or the no long valid old address
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if this is a down event.
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.Pp
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The format of the address depends on the address family, for IPv4 it is the
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usual dotted quad notation, for IPv6 the colon separated standard notation.
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.El
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.Sh SEE ALSO
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.Xr route 4 ,
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.Xr ifconfig.if 5 ,
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.Xr pppoe 8 ,
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.Xr rc.d 8 ,
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.Xr route 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Nx 1.6 .
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.Sh AUTHOR
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The program was written by
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.ie t Martin Husemann.
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.el Martin Husemann.
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@ -0,0 +1,306 @@
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/*
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* Copyright (c) 2001 Martin Husemann <martin@duskware.de>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. The name of the author may not be used to endorse or promote products
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* derived from this software withough specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/file.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <sys/mbuf.h>
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#include <sys/sysctl.h>
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#include <net/if.h>
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#include <net/if_dl.h>
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#include <net/route.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include <unistd.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <netdb.h>
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#include <sys/queue.h>
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/* local functions */
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static void usage(void);
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static void dispatch(void*, size_t);
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static void check_addrs(char *cp, int addrs, int is_up);
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static void invoke_script(struct sockaddr *sa, int is_up, int ifindex);
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static void list_interfaces(const char *ifnames);
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static void rescan_interfaces(void);
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static void free_interfaces(void);
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static int find_interface(int index);
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/* stolen from /sbin/route */
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#define ROUNDUP(a) \
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((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
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#define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
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/* global variables */
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static int verbose = 0;
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static const char *up_script = NULL;
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static const char *down_script = NULL;
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struct interface_data {
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SLIST_ENTRY(interface_data) next;
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int index;
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char * ifname;
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};
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SLIST_HEAD(,interface_data) ifs = SLIST_HEAD_INITIALIZER(ifs);
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int
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main(int argc, char **argv)
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{
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int c, s, n;
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int errs = 0;
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char msg[2048], *msgp;
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while ((c = getopt(argc, argv, "vhu:d:")) != -1)
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switch (c) {
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case 'h':
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usage();
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return 0;
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case 'v':
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verbose++;
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break;
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case 'u':
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up_script = optarg;
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break;
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case 'd':
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down_script = optarg;
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break;
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default:
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errs++;
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break;
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}
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if (errs)
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usage();
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argv += optind;
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argc -= optind;
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if (argc <= 0)
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usage();
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if (verbose) {
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printf("up_script: %s\ndown_script: %s\n",
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up_script, down_script);
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printf("verbosity = %d\n", verbose);
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}
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while (argc > 0) {
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list_interfaces(argv[0]);
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argv++; argc--;
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}
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if (!verbose)
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daemon(0,0);
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s = socket(PF_ROUTE, SOCK_RAW, 0);
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if (s < 0) {
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perror("open routing socket");
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exit(1);
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}
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for (;;) {
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n = read(s, msg, sizeof msg);
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msgp = msg;
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for (msgp = msg; n > 0; n -= ((struct rt_msghdr*)msgp)->rtm_msglen, msgp += ((struct rt_msghdr*)msgp)->rtm_msglen) {
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dispatch(msgp, n);
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}
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}
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close(s);
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free_interfaces();
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exit(0);
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}
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static void
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usage()
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{
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fprintf(stderr,
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"usage:\n"
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"\tifwatchd [-h] [-v] [-u up-script] [-d down-script] ifname(s)\n"
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"\twhere:\n"
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"\t -h show this help message\n"
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"\t -v verbose/debug output, don't run in background\n"
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"\t -u <cmd> specify command to run on interface up event\n"
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"\t -d <cmd> specify command to run on interface down event\n");
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exit(1);
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}
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static void
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dispatch(void *msg, size_t len)
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{
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struct rt_msghdr *hd = msg;
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struct ifa_msghdr *ifam;
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int is_up;
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is_up = 0;
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switch (hd->rtm_type) {
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case RTM_NEWADDR:
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is_up = 1;
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goto work;
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case RTM_DELADDR:
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is_up = 0;
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goto work;
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case RTM_IFANNOUNCE:
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rescan_interfaces();
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break;
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}
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if (verbose)
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printf("unknown message ignored\n");
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return;
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work:
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ifam = (struct ifa_msghdr *)msg;
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check_addrs((char *)(ifam + 1), ifam->ifam_addrs, is_up);
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}
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static void
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check_addrs(cp, addrs, is_up)
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char *cp;
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int addrs, is_up;
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{
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struct sockaddr *sa;
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int ifndx = 0, i;
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if (addrs == 0)
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return;
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for (i = 1; i; i <<= 1) {
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if (i & addrs) {
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sa = (struct sockaddr *)cp;
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if (i == RTA_IFP) {
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struct sockaddr_dl * li = (struct sockaddr_dl*)sa;
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ifndx = li->sdl_index;
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if (!find_interface(ifndx)) {
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if (verbose)
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printf("ignoring change on interface #%d\n", ifndx);
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return;
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}
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} else if (i == RTA_IFA) {
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invoke_script(sa, is_up, ifndx);
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}
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ADVANCE(cp, sa);
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}
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}
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}
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static void
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invoke_script(sa, is_up, ifindex)
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struct sockaddr *sa;
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int is_up, ifindex;
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{
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char addr[NI_MAXHOST], ifname_buf[IFNAMSIZ], *ifname, *cmd;
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const char *script;
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ifname = if_indextoname(ifindex, ifname_buf);
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if (sa->sa_len == 0) {
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fprintf(stderr, "illegal socket address (sa_len == 0)\n");
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return;
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}
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if (getnameinfo(sa, sa->sa_len, addr, sizeof addr, NULL, 0, NI_NUMERICHOST)) {
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if (verbose)
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printf("getnameinfo failed\n");
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return; /* this address can not be handled */
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}
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script = is_up? up_script : down_script;
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if (script == NULL) return;
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asprintf(&cmd, "%s \"%s\" %s \"%s\"", script, ifname,
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is_up?"up":"down", addr);
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if (cmd == NULL) {
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fprintf(stderr, "out of memory\n");
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return;
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}
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if (verbose)
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printf("calling: %s\n", cmd);
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system(cmd);
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free(cmd);
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}
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static void list_interfaces(const char *ifnames)
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{
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char * names = strdup(ifnames);
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char * name, *lasts;
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static const char sep[] = " \t";
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struct interface_data * p;
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for (name = strtok_r(names, sep, &lasts); name != NULL; name = strtok_r(NULL, sep, &lasts)) {
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p = malloc(sizeof(*p));
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SLIST_INSERT_HEAD(&ifs, p, next);
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p->ifname = strdup(name);
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p->index = if_nametoindex(p->ifname);
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if (verbose)
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printf("interface \"%s\" has index %d\n", p->ifname, p->index);
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}
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free(names);
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}
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static void rescan_interfaces()
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{
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struct interface_data * p;
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SLIST_FOREACH(p, &ifs, next) {
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p->index = if_nametoindex(p->ifname);
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if (verbose)
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printf("interface \"%s\" has index %d\n", p->ifname, p->index);
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}
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}
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static void free_interfaces()
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{
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struct interface_data * p;
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while (!SLIST_EMPTY(&ifs)) {
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p = SLIST_FIRST(&ifs);
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SLIST_REMOVE_HEAD(&ifs, next);
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free(p->ifname);
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free(p);
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}
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}
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static int find_interface(index)
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int index;
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{
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struct interface_data * p;
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SLIST_FOREACH(p, &ifs, next)
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if (p->index == index)
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return 1;
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return 0;
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}
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