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      1 /*
      2  * dhcpcd - DHCP client daemon
      3  * Copyright (c) 2006-2010 Roy Marples <roy (at) marples.name>
      4  * All rights reserved
      5 
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include <sys/stat.h>
     29 #include <sys/uio.h>
     30 #include <sys/wait.h>
     31 
     32 #include <netinet/in.h>
     33 #include <arpa/inet.h>
     34 
     35 #include <ctype.h>
     36 #include <errno.h>
     37 #include <signal.h>
     38 #include <stdlib.h>
     39 #include <string.h>
     40 #include <unistd.h>
     41 
     42 #include <rump/rump_syscalls.h>
     43 
     44 #include "common.h"
     45 #include "configure.h"
     46 #include "dhcp.h"
     47 #include "if-options.h"
     48 #include "net.h"
     49 
     50 /* Some systems have route metrics */
     51 #ifndef HAVE_ROUTE_METRIC
     52 # ifdef __linux__
     53 #  define HAVE_ROUTE_METRIC 1
     54 # endif
     55 # ifndef HAVE_ROUTE_METRIC
     56 #  define HAVE_ROUTE_METRIC 0
     57 # endif
     58 #endif
     59 
     60 static struct rt *routes;
     61 
     62 static struct rt *
     63 find_route(struct rt *rts, const struct rt *r, struct rt **lrt,
     64     const struct rt *srt)
     65 {
     66 	struct rt *rt;
     67 
     68 	if (lrt)
     69 		*lrt = NULL;
     70 	for (rt = rts; rt; rt = rt->next) {
     71 		if (rt->dest.s_addr == r->dest.s_addr &&
     72 #if HAVE_ROUTE_METRIC
     73 		    (srt || (!rt->iface ||
     74 			rt->iface->metric == r->iface->metric)) &&
     75 #endif
     76                     (!srt || srt != rt) &&
     77 		    rt->net.s_addr == r->net.s_addr)
     78 			return rt;
     79 		if (lrt)
     80 			*lrt = rt;
     81 	}
     82 	return NULL;
     83 }
     84 
     85 static void
     86 desc_route(const char *cmd, const struct rt *rt, const char *ifname)
     87 {
     88 	char addr[sizeof("000.000.000.000") + 1];
     89 
     90 	strlcpy(addr, inet_ntoa(rt->dest), sizeof(addr));
     91 	if (rt->gate.s_addr == INADDR_ANY)
     92 		fprintf(stderr, "%s: %s route to %s/%d\n", ifname, cmd,
     93 		    addr, inet_ntocidr(rt->net));
     94 	else if (rt->gate.s_addr == rt->dest.s_addr &&
     95 	    rt->net.s_addr == INADDR_BROADCAST)
     96 		fprintf(stderr, "%s: %s host route to %s\n", ifname, cmd,
     97 		    addr);
     98 	else if (rt->dest.s_addr == INADDR_ANY && rt->net.s_addr == INADDR_ANY)
     99 		fprintf(stderr, "%s: %s default route via %s\n", ifname, cmd,
    100 		    inet_ntoa(rt->gate));
    101 	else
    102 		fprintf(stderr, "%s: %s route to %s/%d via %s\n", ifname, cmd,
    103 		    addr, inet_ntocidr(rt->net), inet_ntoa(rt->gate));
    104 }
    105 
    106 /* If something other than dhcpcd removes a route,
    107  * we need to remove it from our internal table. */
    108 int
    109 route_deleted(const struct rt *rt)
    110 {
    111 	struct rt *f, *l;
    112 
    113 	f = find_route(routes, rt, &l, NULL);
    114 	if (f == NULL)
    115 		return 0;
    116 	desc_route("removing", f, f->iface->name);
    117 	if (l)
    118 		l->next = f->next;
    119 	else
    120 		routes = f->next;
    121 	free(f);
    122 	return 1;
    123 }
    124 
    125 static int
    126 n_route(struct rt *rt, const struct interface *iface)
    127 {
    128 	/* Don't set default routes if not asked to */
    129 	if (rt->dest.s_addr == 0 &&
    130 	    rt->net.s_addr == 0 &&
    131 	    !(iface->state->options->options & DHCPCD_GATEWAY))
    132 		return -1;
    133 
    134 	desc_route("adding", rt, iface->name);
    135 	if (!add_route(iface, &rt->dest, &rt->net, &rt->gate, iface->metric))
    136 		return 0;
    137 	if (errno == EEXIST) {
    138 		/* Pretend we added the subnet route */
    139 		if (rt->dest.s_addr == (iface->addr.s_addr & iface->net.s_addr) &&
    140 		    rt->net.s_addr == iface->net.s_addr &&
    141 		    rt->gate.s_addr == 0)
    142 			return 0;
    143 		else
    144 			return -1;
    145 	}
    146 	fprintf(stderr, "%s: add_route failed: %d\n", iface->name, errno);
    147 	return -1;
    148 }
    149 
    150 static int
    151 c_route(struct rt *ort, struct rt *nrt, const struct interface *iface)
    152 {
    153 	/* Don't set default routes if not asked to */
    154 	if (nrt->dest.s_addr == 0 &&
    155 	    nrt->net.s_addr == 0 &&
    156 	    !(iface->state->options->options & DHCPCD_GATEWAY))
    157 		return -1;
    158 
    159 	desc_route("changing", nrt, iface->name);
    160 	/* We delete and add the route so that we can change metric.
    161 	 * This also has the nice side effect of flushing ARP entries so
    162 	 * we don't have to do that manually. */
    163 	del_route(ort->iface, &ort->dest, &ort->net, &ort->gate,
    164 	    ort->iface->metric);
    165 	if (!add_route(iface, &nrt->dest, &nrt->net, &nrt->gate,
    166 		iface->metric))
    167 		return 0;
    168 	fprintf(stderr, "%s: add_route failed: %d\n", iface->name, errno);
    169 	return -1;
    170 }
    171 
    172 static int
    173 d_route(struct rt *rt, const struct interface *iface, int metric)
    174 {
    175 	int retval;
    176 
    177 	desc_route("deleting", rt, iface->name);
    178 	retval = del_route(iface, &rt->dest, &rt->net, &rt->gate, metric);
    179 	if (retval != 0 && errno != ENOENT && errno != ESRCH)
    180 		fprintf(stderr,"%s: del_route: %d\n", iface->name, errno);
    181 	return retval;
    182 }
    183 
    184 static struct rt *
    185 get_subnet_route(struct dhcp_message *dhcp)
    186 {
    187 	in_addr_t addr;
    188 	struct in_addr net;
    189 	struct rt *rt;
    190 
    191 	addr = dhcp->yiaddr;
    192 	if (addr == 0)
    193 		addr = dhcp->ciaddr;
    194 	/* Ensure we have all the needed values */
    195 	if (get_option_addr(&net, dhcp, DHO_SUBNETMASK) == -1)
    196 		net.s_addr = get_netmask(addr);
    197 	if (net.s_addr == INADDR_BROADCAST || net.s_addr == INADDR_ANY)
    198 		return NULL;
    199 	rt = malloc(sizeof(*rt));
    200 	rt->dest.s_addr = addr & net.s_addr;
    201 	rt->net.s_addr = net.s_addr;
    202 	rt->gate.s_addr = 0;
    203 	return rt;
    204 }
    205 
    206 static struct rt *
    207 add_subnet_route(struct rt *rt, const struct interface *iface)
    208 {
    209 	struct rt *r;
    210 
    211 	if (iface->net.s_addr == INADDR_BROADCAST ||
    212 	    iface->net.s_addr == INADDR_ANY ||
    213 	    (iface->state->options->options &
    214 	     (DHCPCD_INFORM | DHCPCD_STATIC) &&
    215 	     iface->state->options->req_addr.s_addr == INADDR_ANY))
    216 		return rt;
    217 
    218 	r = xmalloc(sizeof(*r));
    219 	r->dest.s_addr = iface->addr.s_addr & iface->net.s_addr;
    220 	r->net.s_addr = iface->net.s_addr;
    221 	r->gate.s_addr = 0;
    222 	r->next = rt;
    223 	return r;
    224 }
    225 
    226 static struct rt *
    227 get_routes(const struct interface *iface)
    228 {
    229 	struct rt *rt, *nrt = NULL, *r = NULL;
    230 
    231 	if (iface->state->options->routes != NULL) {
    232 		for (rt = iface->state->options->routes;
    233 		     rt != NULL;
    234 		     rt = rt->next)
    235 		{
    236 			if (rt->gate.s_addr == 0)
    237 				break;
    238 			if (r == NULL)
    239 				r = nrt = xmalloc(sizeof(*r));
    240 			else {
    241 				r->next = xmalloc(sizeof(*r));
    242 				r = r->next;
    243 			}
    244 			memcpy(r, rt, sizeof(*r));
    245 			r->next = NULL;
    246 		}
    247 		return nrt;
    248 	}
    249 
    250 	return get_option_routes(iface->state->new,
    251 	    iface->name, &iface->state->options->options);
    252 }
    253 
    254 /* Some DHCP servers add set host routes by setting the gateway
    255  * to the assigned IP address. This differs from our notion of a host route
    256  * where the gateway is the destination address, so we fix it. */
    257 static struct rt *
    258 massage_host_routes(struct rt *rt, const struct interface *iface)
    259 {
    260 	struct rt *r;
    261 
    262 	for (r = rt; r; r = r->next)
    263 		if (r->gate.s_addr == iface->addr.s_addr &&
    264 		    r->net.s_addr == INADDR_BROADCAST)
    265 			r->gate.s_addr = r->dest.s_addr;
    266 	return rt;
    267 }
    268 
    269 static struct rt *
    270 add_destination_route(struct rt *rt, const struct interface *iface)
    271 {
    272 	struct rt *r;
    273 
    274 	if (!(iface->flags & IFF_POINTOPOINT) ||
    275 	    !has_option_mask(iface->state->options->dstmask, DHO_ROUTER))
    276 		return rt;
    277 	r = xmalloc(sizeof(*r));
    278 	r->dest.s_addr = INADDR_ANY;
    279 	r->net.s_addr = INADDR_ANY;
    280 	r->gate.s_addr = iface->dst.s_addr;
    281 	r->next = rt;
    282 	return r;
    283 }
    284 
    285 /* We should check to ensure the routers are on the same subnet
    286  * OR supply a host route. If not, warn and add a host route. */
    287 static struct rt *
    288 add_router_host_route(struct rt *rt, const struct interface *ifp)
    289 {
    290 	struct rt *rtp, *rtl, *rtn;
    291 	const char *cp, *cp2, *cp3, *cplim;
    292 
    293 	for (rtp = rt, rtl = NULL; rtp; rtl = rtp, rtp = rtp->next) {
    294 		if (rtp->dest.s_addr != INADDR_ANY)
    295 			continue;
    296 		/* Scan for a route to match */
    297 		for (rtn = rt; rtn != rtp; rtn = rtn->next) {
    298 			/* match host */
    299 			if (rtn->dest.s_addr == rtp->gate.s_addr)
    300 				break;
    301 			/* match subnet */
    302 			cp = (const char *)&rtp->gate.s_addr;
    303 			cp2 = (const char *)&rtn->dest.s_addr;
    304 			cp3 = (const char *)&rtn->net.s_addr;
    305 			cplim = cp3 + sizeof(rtn->net.s_addr);
    306 			while (cp3 < cplim) {
    307 				if ((*cp++ ^ *cp2++) & *cp3++)
    308 					break;
    309 			}
    310 			if (cp3 == cplim)
    311 				break;
    312 		}
    313 		if (rtn != rtp)
    314 			continue;
    315 		if (ifp->flags & IFF_NOARP) {
    316 			fprintf(stderr,
    317 			    "%s: forcing router %s through interface\n",
    318 			    ifp->name, inet_ntoa(rtp->gate));
    319 			rtp->gate.s_addr = 0;
    320 			continue;
    321 		}
    322 		fprintf(stderr, "%s: router %s requires a host route\n",
    323 		    ifp->name, inet_ntoa(rtp->gate));
    324 		rtn = xmalloc(sizeof(*rtn));
    325 		rtn->dest.s_addr = rtp->gate.s_addr;
    326 		rtn->net.s_addr = INADDR_BROADCAST;
    327 		rtn->gate.s_addr = rtp->gate.s_addr;
    328 		rtn->next = rtp;
    329 		if (rtl == NULL)
    330 			rt = rtn;
    331 		else
    332 			rtl->next = rtn;
    333 	}
    334 	return rt;
    335 }
    336 
    337 void
    338 build_routes(void)
    339 {
    340 	struct rt *nrs = NULL, *dnr, *or, *rt, *rtn, *rtl, *lrt = NULL;
    341 	const struct interface *ifp;
    342 
    343 	for (ifp = ifaces; ifp; ifp = ifp->next) {
    344 		if (ifp->state->new == NULL)
    345 			continue;
    346 		dnr = get_routes(ifp);
    347 		dnr = massage_host_routes(dnr, ifp);
    348 		dnr = add_subnet_route(dnr, ifp);
    349 		dnr = add_router_host_route(dnr, ifp);
    350 		dnr = add_destination_route(dnr, ifp);
    351 		for (rt = dnr; rt && (rtn = rt->next, 1); lrt = rt, rt = rtn) {
    352 			rt->iface = ifp;
    353 			/* Is this route already in our table? */
    354 			if ((find_route(nrs, rt, NULL, NULL)) != NULL)
    355 				continue;
    356 			/* Do we already manage it? */
    357 			if ((or = find_route(routes, rt, &rtl, NULL))) {
    358 				if (or->iface != ifp ||
    359 				    rt->gate.s_addr != or->gate.s_addr)
    360 				{
    361 					if (c_route(or, rt, ifp) != 0)
    362 						continue;
    363 				}
    364 				if (rtl != NULL)
    365 					rtl->next = or->next;
    366 				else
    367 					routes = or->next;
    368 				free(or);
    369 			} else {
    370 				if (n_route(rt, ifp) != 0)
    371 					continue;
    372 			}
    373 			if (dnr == rt)
    374 				dnr = rtn;
    375 			else if (lrt)
    376 				lrt->next = rtn;
    377 			rt->next = nrs;
    378 			nrs = rt;
    379 		}
    380 		free_routes(dnr);
    381 	}
    382 
    383 	/* Remove old routes we used to manage */
    384 	for (rt = routes; rt; rt = rt->next) {
    385 		if (find_route(nrs, rt, NULL, NULL) == NULL)
    386 			d_route(rt, rt->iface, rt->iface->metric);
    387 	}
    388 
    389 	free_routes(routes);
    390 	routes = nrs;
    391 }
    392 
    393 static int
    394 delete_address(struct interface *iface)
    395 {
    396 	int retval;
    397 	struct if_options *ifo;
    398 
    399 	ifo = iface->state->options;
    400 	if (ifo->options & DHCPCD_INFORM ||
    401 	    (ifo->options & DHCPCD_STATIC && ifo->req_addr.s_addr == 0))
    402 		return 0;
    403 	fprintf(stderr, "%s: deleting IP address %s/%d\n",
    404 	    iface->name,
    405 	    inet_ntoa(iface->addr),
    406 	    inet_ntocidr(iface->net));
    407 	retval = del_address(iface, &iface->addr, &iface->net);
    408 	if (retval == -1 && errno != EADDRNOTAVAIL)
    409 		fprintf(stderr, "del_address failed: %d\n", errno);
    410 	iface->addr.s_addr = 0;
    411 	iface->net.s_addr = 0;
    412 	return retval;
    413 }
    414 
    415 int
    416 configure(struct interface *iface)
    417 {
    418 	struct dhcp_message *dhcp = iface->state->new;
    419 	struct dhcp_lease *lease = &iface->state->lease;
    420 	struct if_options *ifo = iface->state->options;
    421 	struct rt *rt;
    422 
    423 	/* This also changes netmask */
    424 	if (!(ifo->options & DHCPCD_INFORM) ||
    425 	    !has_address(iface->name, &lease->addr, &lease->net))
    426 	{
    427 		fprintf(stderr, "%s: adding IP address %s/%d\n",
    428 		    iface->name, inet_ntoa(lease->addr),
    429 		    inet_ntocidr(lease->net));
    430 		if (add_address(iface,
    431 			&lease->addr, &lease->net, &lease->brd) == -1 &&
    432 		    errno != EEXIST)
    433 		{
    434 			fprintf(stderr, "add_address failed\n");
    435 			return -1;
    436 		}
    437 	}
    438 
    439 	/* Now delete the old address if different */
    440 	if (iface->addr.s_addr != lease->addr.s_addr &&
    441 	    iface->addr.s_addr != 0)
    442 		delete_address(iface);
    443 
    444 	iface->addr.s_addr = lease->addr.s_addr;
    445 	iface->net.s_addr = lease->net.s_addr;
    446 
    447 	/* We need to delete the subnet route to have our metric or
    448 	 * prefer the interface. */
    449 	rt = get_subnet_route(dhcp);
    450 	if (rt != NULL) {
    451 		rt->iface = iface;
    452 		if (!find_route(routes, rt, NULL, NULL))
    453 			del_route(iface, &rt->dest, &rt->net, &rt->gate, 0);
    454 		free(rt);
    455 	}
    456 
    457 	build_routes();
    458 
    459 	fprintf(stderr, "lease time: ");
    460 	if (lease->leasetime == ~0U)
    461 		fprintf(stderr, "infinite\n");
    462 	else
    463 		fprintf(stderr, "%u seconds (%.2f days)\n",
    464 		    lease->leasetime, lease->leasetime / (60*60*24+.0));
    465 
    466 	return 0;
    467 }
    468