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ifwatchd.c revision 1.5 
      1 /*	$NetBSD: ifwatchd.c,v 1.5 2002/01/10 20:21:50 martin Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2001-2002 Martin Husemann <martin (at) duskware.de>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. The name of the author may not be used to endorse or promote products
     13  *    derived from this software withough specific prior written permission
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 
     27 /*
     28  * Define this for special treatment of sys/net/if_spppsubr.c based interfaces.
     29  */
     30 #define SPPP_IF_SUPPORT
     31 
     32 #include <sys/types.h>
     33 #include <sys/param.h>
     34 #include <sys/ioctl.h>
     35 #include <sys/socket.h>
     36 #include <sys/queue.h>
     37 #include <net/if.h>
     38 #include <net/if_dl.h>
     39 #ifdef SPPP_IF_SUPPORT
     40 #include <net/if_sppp.h>
     41 #endif
     42 #include <net/route.h>
     43 #include <netinet/in.h>
     44 #include <arpa/inet.h>
     45 
     46 #include <stdio.h>
     47 #include <stdlib.h>
     48 #include <string.h>
     49 #include <unistd.h>
     50 #include <netdb.h>
     51 #include <err.h>
     52 #include <ifaddrs.h>
     53 
     54 /* local functions */
     55 static void usage(void);
     56 static void dispatch(void*, size_t);
     57 static void check_addrs(char *cp, int addrs, int is_up);
     58 static void invoke_script(struct sockaddr *sa, struct sockaddr *dst, int is_up, int ifindex);
     59 static void list_interfaces(const char *ifnames);
     60 static void rescan_interfaces(void);
     61 static void free_interfaces(void);
     62 static int find_interface(int index);
     63 static void run_initial_ups(void);
     64 
     65 #ifdef SPPP_IF_SUPPORT
     66 static int if_is_connected(const char * ifname);
     67 #else
     68 #define	if_is_connected(X)	1
     69 #endif
     70 
     71 /* stolen from /sbin/route */
     72 #define ROUNDUP(a) \
     73 	((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
     74 #define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
     75 
     76 /* global variables */
     77 static int verbose = 0;
     78 static int inhibit_initial = 0;
     79 static const char *up_script = NULL;
     80 static const char *down_script = NULL;
     81 
     82 struct interface_data {
     83 	SLIST_ENTRY(interface_data) next;
     84 	int index;
     85 	char * ifname;
     86 };
     87 SLIST_HEAD(,interface_data) ifs = SLIST_HEAD_INITIALIZER(ifs);
     88 
     89 int
     90 main(int argc, char **argv)
     91 {
     92 	int c, s, n;
     93 	int errs = 0;
     94 	char msg[2048], *msgp;
     95 
     96 	while ((c = getopt(argc, argv, "vhiu:d:")) != -1)
     97 		switch (c) {
     98 		case 'h':
     99 			usage();
    100 			return 0;
    101 		case 'i':
    102 			inhibit_initial = 1;
    103 			break;
    104 		case 'v':
    105 			verbose++;
    106 			break;
    107 
    108 		case 'u':
    109 			up_script = optarg;
    110 			break;
    111 
    112 		case 'd':
    113 			down_script = optarg;
    114 			break;
    115 
    116 		default:
    117 			errs++;
    118 			break;
    119 		}
    120 
    121 	if (errs)
    122 		usage();
    123 
    124 	argv += optind;
    125 	argc -= optind;
    126 
    127 	if (argc <= 0)
    128 		usage();
    129 
    130 	if (verbose) {
    131 		printf("up_script: %s\ndown_script: %s\n",
    132 			up_script, down_script);
    133 		printf("verbosity = %d\n", verbose);
    134 	}
    135 
    136 	while (argc > 0) {
    137 	    list_interfaces(argv[0]);
    138 	    argv++; argc--;
    139 	}
    140 
    141 	if (!verbose)
    142 		daemon(0,0);
    143 
    144 	if (!inhibit_initial)
    145 		run_initial_ups();
    146 
    147 	s = socket(PF_ROUTE, SOCK_RAW, 0);
    148 	if (s < 0) {
    149 		perror("open routing socket");
    150 		exit(1);
    151 	}
    152 
    153 	for (;;) {
    154 		n = read(s, msg, sizeof msg);
    155 		msgp = msg;
    156 		for (msgp = msg; n > 0; n -= ((struct rt_msghdr*)msgp)->rtm_msglen, msgp += ((struct rt_msghdr*)msgp)->rtm_msglen) {
    157 			dispatch(msgp, n);
    158 
    159 		}
    160 	}
    161 
    162 	close(s);
    163 	free_interfaces();
    164 
    165 	exit(0);
    166 }
    167 
    168 static void
    169 usage()
    170 {
    171 	fprintf(stderr,
    172 	    "usage:\n"
    173 	    "\tifwatchd [-h] [-v] [-u up-script] [-d down-script] ifname(s)\n"
    174 	    "\twhere:\n"
    175 	    "\t -h       show this help message\n"
    176 	    "\t -v       verbose/debug output, don't run in background\n"
    177 	    "\t -i       no (!) initial run of the up script if the interface\n"
    178 	    "\t          is already up on ifwatchd startup\n"
    179 	    "\t -u <cmd> specify command to run on interface up event\n"
    180 	    "\t -d <cmd> specify command to run on interface down event\n");
    181 	exit(1);
    182 }
    183 
    184 static void
    185 dispatch(void *msg, size_t len)
    186 {
    187 	struct rt_msghdr *hd = msg;
    188 	struct ifa_msghdr *ifam;
    189 	int is_up;
    190 
    191 	is_up = 0;
    192 	switch (hd->rtm_type) {
    193 	case RTM_NEWADDR:
    194 		is_up = 1;
    195 		goto work;
    196 	case RTM_DELADDR:
    197 		is_up = 0;
    198 		goto work;
    199 	case RTM_IFANNOUNCE:
    200 		rescan_interfaces();
    201 		break;
    202 	}
    203 	if (verbose)
    204 		printf("unknown message ignored\n");
    205 	return;
    206 
    207 work:
    208 	ifam = (struct ifa_msghdr *)msg;
    209 	check_addrs((char *)(ifam + 1), ifam->ifam_addrs, is_up);
    210 }
    211 
    212 static void
    213 check_addrs(cp, addrs, is_up)
    214 	char    *cp;
    215 	int     addrs, is_up;
    216 {
    217 	struct sockaddr *sa, *ifa = NULL, *brd = NULL;
    218 	int ifndx = 0, i;
    219 
    220 	if (addrs == 0)
    221 	    return;
    222 	for (i = 1; i; i <<= 1) {
    223 	    if (i & addrs) {
    224 		sa = (struct sockaddr *)cp;
    225 		if (i == RTA_IFP) {
    226 		    struct sockaddr_dl * li = (struct sockaddr_dl*)sa;
    227 		    ifndx = li->sdl_index;
    228 		    if (!find_interface(ifndx)) {
    229 			if (verbose)
    230 			    printf("ignoring change on interface #%d\n", ifndx);
    231 			return;
    232 		    }
    233 		} else if (i == RTA_IFA) {
    234 		    ifa = sa;
    235 		} else if (i == RTA_BRD) {
    236 		    brd = sa;
    237 		}
    238 		ADVANCE(cp, sa);
    239 	    }
    240 	}
    241 	if (ifa != NULL)
    242 	   invoke_script(ifa, brd, is_up, ifndx);
    243 }
    244 
    245 static void
    246 invoke_script(sa, dest, is_up, ifindex)
    247 	struct sockaddr *sa, *dest;
    248 	int is_up, ifindex;
    249 {
    250 	char addr[NI_MAXHOST], daddr[NI_MAXHOST], ifname_buf[IFNAMSIZ],
    251 	     *ifname, *cmd;
    252 	const char *script;
    253 
    254 	daddr[0] = 0;
    255 	ifname = if_indextoname(ifindex, ifname_buf);
    256 	if (sa->sa_len == 0) {
    257 	    fprintf(stderr, "illegal socket address (sa_len == 0)\n");
    258 	    return;
    259 	}
    260 
    261 	if (getnameinfo(sa, sa->sa_len, addr, sizeof addr, NULL, 0, NI_NUMERICHOST)) {
    262 	    if (verbose)
    263 		printf("getnameinfo failed\n");
    264 	    return;	/* this address can not be handled */
    265 	}
    266 	if (dest != NULL) {
    267 	    if (getnameinfo(dest, dest->sa_len, daddr, sizeof daddr, NULL, 0, NI_NUMERICHOST)) {
    268 		if (verbose)
    269 		    printf("getnameinfo failed\n");
    270 		return;	/* this address can not be handled */
    271 	    }
    272 	}
    273 
    274 	script = is_up? up_script : down_script;
    275 	if (script == NULL) return;
    276 
    277 	asprintf(&cmd, "%s \"%s\" %s \"%s\" \"%s\"", script, ifname,
    278 			is_up?"up":"down", addr, daddr);
    279 	if (cmd == NULL) {
    280 	    fprintf(stderr, "out of memory\n");
    281 	    return;
    282 	}
    283 	if (verbose)
    284 	    printf("calling: %s\n", cmd);
    285 	system(cmd);
    286 	free(cmd);
    287 }
    288 
    289 static void list_interfaces(const char *ifnames)
    290 {
    291 	char * names = strdup(ifnames);
    292 	char * name, *lasts;
    293 	static const char sep[] = " \t";
    294 	struct interface_data * p;
    295 
    296 	for (name = strtok_r(names, sep, &lasts); name != NULL; name = strtok_r(NULL, sep, &lasts)) {
    297 	    p = malloc(sizeof(*p));
    298 	    SLIST_INSERT_HEAD(&ifs, p, next);
    299 	    p->ifname = strdup(name);
    300 	    p->index = if_nametoindex(p->ifname);
    301 	    if (verbose)
    302 		printf("interface \"%s\" has index %d\n", p->ifname, p->index);
    303 	}
    304 	free(names);
    305 }
    306 
    307 static void rescan_interfaces()
    308 {
    309 	struct interface_data * p;
    310 
    311 	SLIST_FOREACH(p, &ifs, next) {
    312 	    p->index = if_nametoindex(p->ifname);
    313 	    if (verbose)
    314 		printf("interface \"%s\" has index %d\n", p->ifname, p->index);
    315 	}
    316 }
    317 
    318 static void free_interfaces()
    319 {
    320 	struct interface_data * p;
    321 
    322 	while (!SLIST_EMPTY(&ifs)) {
    323 	    p = SLIST_FIRST(&ifs);
    324 	    SLIST_REMOVE_HEAD(&ifs, next);
    325 	    free(p->ifname);
    326 	    free(p);
    327 	}
    328 }
    329 
    330 static int find_interface(index)
    331 	int index;
    332 {
    333 	struct interface_data * p;
    334 
    335 	SLIST_FOREACH(p, &ifs, next)
    336 	    if (p->index == index)
    337 		return 1;
    338 	return 0;
    339 }
    340 
    341 static void run_initial_ups()
    342 {
    343 	struct interface_data * ifd;
    344 	struct ifaddrs *res = NULL, *p;
    345 
    346 	if (getifaddrs(&res) == 0) {
    347 	    for (p = res; p; p = p->ifa_next) {
    348 		if ((p->ifa_flags & IFF_UP) == 0)
    349 		    continue;
    350 		if (p->ifa_addr == NULL)
    351 		    continue;
    352 		if (p->ifa_addr->sa_family == AF_LINK)
    353 		    continue;
    354 		SLIST_FOREACH(ifd, &ifs, next) {
    355 		    if (strcmp(ifd->ifname, p->ifa_name) == 0) {
    356 		    	if (if_is_connected(ifd->ifname))
    357 			    invoke_script(p->ifa_addr, p->ifa_dstaddr, 1, ifd->index);
    358 			break;
    359 		    }
    360 		}
    361 	    }
    362 	    freeifaddrs(res);
    363 	}
    364 }
    365 
    366 #ifdef SPPP_IF_SUPPORT
    367 /*
    368  * Special case support for in-kernel PPP interfaces.
    369  * If these are IFF_UP, but have not yet connected or completed authentication
    370  * we don't want to call the up script in the initial interface scan (there
    371  * will be an UP event generated later, when IPCP completes, anyway).
    372  *
    373  * If this is no if_spppsubr.c based interface, this ioctl just fails and we
    374  * treat is as connected.
    375  */
    376 static int
    377 if_is_connected(const char * ifname)
    378 {
    379 	int s, err;
    380 	struct spppstatus status;
    381 
    382 	memset(&status, 0, sizeof status);
    383 	strncpy(status.ifname, ifname, sizeof status.ifname);
    384 	s = socket(AF_INET, SOCK_DGRAM, 0);
    385 	if (s < 0)
    386 	    return 1;	/* no idea how to handle this... */
    387 	err = ioctl(s, SPPPGETSTATUS, &status);
    388 	if (err != 0)
    389 	    /* not if_spppsubr.c based - call it connected */
    390 	    status.phase = SPPP_PHASE_NETWORK;
    391 	close(s);
    392 	return status.phase == SPPP_PHASE_NETWORK;
    393 }
    394 #endif
    395