xref: /freebsd/sys/netinet/in.c (revision 3e0f6b97b257a96f7275e4442204263e44b16686)
1 /*
2  * Copyright (c) 1982, 1986, 1991, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  *	@(#)in.c	8.4 (Berkeley) 1/9/95
34  *	$FreeBSD$
35  */
36 
37 #include <sys/param.h>
38 #include <sys/queue.h>
39 #include <sys/systm.h>
40 #include <sys/ioctl.h>
41 #include <sys/errno.h>
42 #include <sys/malloc.h>
43 #include <sys/socket.h>
44 #include <sys/socketvar.h>
45 #include <sys/kernel.h>
46 #include <sys/sysctl.h>
47 
48 #include <net/if.h>
49 #include <net/route.h>
50 
51 #include <netinet/in_systm.h>
52 #include <netinet/in.h>
53 #include <netinet/in_var.h>
54 #include <netinet/if_ether.h>
55 
56 #include <netinet/igmp_var.h>
57 
58 static void	in_socktrim __P((struct sockaddr_in *));
59 static int	in_ifinit __P((struct ifnet *,
60 	    struct in_ifaddr *, struct sockaddr_in *, int));
61 
62 static int subnetsarelocal = 0;
63 SYSCTL_INT(_net_inet_ip, OID_AUTO, subnets_are_local, CTLFLAG_RW,
64 	&subnetsarelocal, 0, "");
65 
66 struct in_multihead in_multihead; /* XXX BSS initialization */
67 
68 /*
69  * Return 1 if an internet address is for a ``local'' host
70  * (one to which we have a connection).  If subnetsarelocal
71  * is true, this includes other subnets of the local net.
72  * Otherwise, it includes only the directly-connected (sub)nets.
73  */
74 int
75 in_localaddr(in)
76 	struct in_addr in;
77 {
78 	register u_long i = ntohl(in.s_addr);
79 	register struct in_ifaddr *ia;
80 
81 	if (subnetsarelocal) {
82 		for (ia = in_ifaddrhead.tqh_first; ia;
83 		     ia = ia->ia_link.tqe_next)
84 			if ((i & ia->ia_netmask) == ia->ia_net)
85 				return (1);
86 	} else {
87 		for (ia = in_ifaddrhead.tqh_first; ia;
88 		     ia = ia->ia_link.tqe_next)
89 			if ((i & ia->ia_subnetmask) == ia->ia_subnet)
90 				return (1);
91 	}
92 	return (0);
93 }
94 
95 /*
96  * Determine whether an IP address is in a reserved set of addresses
97  * that may not be forwarded, or whether datagrams to that destination
98  * may be forwarded.
99  */
100 int
101 in_canforward(in)
102 	struct in_addr in;
103 {
104 	register u_long i = ntohl(in.s_addr);
105 	register u_long net;
106 
107 	if (IN_EXPERIMENTAL(i) || IN_MULTICAST(i))
108 		return (0);
109 	if (IN_CLASSA(i)) {
110 		net = i & IN_CLASSA_NET;
111 		if (net == 0 || net == (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))
112 			return (0);
113 	}
114 	return (1);
115 }
116 
117 /*
118  * Trim a mask in a sockaddr
119  */
120 static void
121 in_socktrim(ap)
122 struct sockaddr_in *ap;
123 {
124     register char *cplim = (char *) &ap->sin_addr;
125     register char *cp = (char *) (&ap->sin_addr + 1);
126 
127     ap->sin_len = 0;
128     while (--cp >= cplim)
129         if (*cp) {
130 	    (ap)->sin_len = cp - (char *) (ap) + 1;
131 	    break;
132 	}
133 }
134 
135 static int in_interfaces;	/* number of external internet interfaces */
136 
137 /*
138  * Generic internet control operations (ioctl's).
139  * Ifp is 0 if not an interface-specific ioctl.
140  */
141 /* ARGSUSED */
142 int
143 in_control(so, cmd, data, ifp)
144 	struct socket *so;
145 	u_long cmd;
146 	caddr_t data;
147 	register struct ifnet *ifp;
148 {
149 	register struct ifreq *ifr = (struct ifreq *)data;
150 	register struct in_ifaddr *ia = 0, *iap;
151 	register struct ifaddr *ifa;
152 	struct in_ifaddr *oia;
153 	struct in_aliasreq *ifra = (struct in_aliasreq *)data;
154 	struct sockaddr_in oldaddr;
155 	int error, hostIsNew, maskIsNew, s;
156 	u_long i;
157 
158 	/*
159 	 * Find address for this interface, if it exists.
160 	 *
161 	 * If an alias address was specified, find that one instead of
162 	 * the first one on the interface.
163 	 */
164 	if (ifp)
165 		for (iap = in_ifaddrhead.tqh_first; iap;
166 		     iap = iap->ia_link.tqe_next)
167 			if (iap->ia_ifp == ifp) {
168 				if (((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr.s_addr ==
169 				    iap->ia_addr.sin_addr.s_addr) {
170 					ia = iap;
171 					break;
172 				} else if (ia == NULL) {
173 					ia = iap;
174 					if (ifr->ifr_addr.sa_family != AF_INET)
175 						break;
176 				}
177 			}
178 
179 	switch (cmd) {
180 
181 	case SIOCAIFADDR:
182 	case SIOCDIFADDR:
183 		if (ifra->ifra_addr.sin_family == AF_INET) {
184 			for (oia = ia; ia; ia = ia->ia_link.tqe_next) {
185 				if (ia->ia_ifp == ifp  &&
186 				    ia->ia_addr.sin_addr.s_addr ==
187 				    ifra->ifra_addr.sin_addr.s_addr)
188 					break;
189 			}
190 			if ((ifp->if_flags & IFF_POINTOPOINT)
191 			    && (cmd == SIOCAIFADDR)
192 			    && (ifra->ifra_dstaddr.sin_addr.s_addr
193 				== INADDR_ANY)) {
194 				return EDESTADDRREQ;
195 			}
196 		}
197 		if (cmd == SIOCDIFADDR && ia == 0)
198 			return (EADDRNOTAVAIL);
199 		/* FALLTHROUGH */
200 	case SIOCSIFADDR:
201 	case SIOCSIFNETMASK:
202 	case SIOCSIFDSTADDR:
203 		if ((so->so_state & SS_PRIV) == 0)
204 			return (EPERM);
205 
206 		if (ifp == 0)
207 			panic("in_control");
208 		if (ia == (struct in_ifaddr *)0) {
209 			ia = (struct in_ifaddr *)
210 				malloc(sizeof *ia, M_IFADDR, M_WAITOK);
211 			if (ia == (struct in_ifaddr *)NULL)
212 				return (ENOBUFS);
213 			bzero((caddr_t)ia, sizeof *ia);
214 			/*
215 			 * Protect from ipintr() traversing address list
216 			 * while we're modifying it.
217 			 */
218 			s = splnet();
219 
220 			TAILQ_INSERT_TAIL(&in_ifaddrhead, ia, ia_link);
221 			ifa = &ia->ia_ifa;
222 			TAILQ_INSERT_TAIL(&ifp->if_addrhead, ifa, ifa_link);
223 
224 			ifa->ifa_addr = (struct sockaddr *)&ia->ia_addr;
225 			ifa->ifa_dstaddr = (struct sockaddr *)&ia->ia_dstaddr;
226 			ifa->ifa_netmask = (struct sockaddr *)&ia->ia_sockmask;
227 			ia->ia_sockmask.sin_len = 8;
228 			if (ifp->if_flags & IFF_BROADCAST) {
229 				ia->ia_broadaddr.sin_len = sizeof(ia->ia_addr);
230 				ia->ia_broadaddr.sin_family = AF_INET;
231 			}
232 			ia->ia_ifp = ifp;
233 			if (!(ifp->if_flags & IFF_LOOPBACK))
234 				in_interfaces++;
235 			splx(s);
236 		}
237 		break;
238 
239 	case SIOCSIFBRDADDR:
240 		if ((so->so_state & SS_PRIV) == 0)
241 			return (EPERM);
242 		/* FALLTHROUGH */
243 
244 	case SIOCGIFADDR:
245 	case SIOCGIFNETMASK:
246 	case SIOCGIFDSTADDR:
247 	case SIOCGIFBRDADDR:
248 		if (ia == (struct in_ifaddr *)0)
249 			return (EADDRNOTAVAIL);
250 		break;
251 	}
252 	switch (cmd) {
253 
254 	case SIOCGIFADDR:
255 		*((struct sockaddr_in *)&ifr->ifr_addr) = ia->ia_addr;
256 		break;
257 
258 	case SIOCGIFBRDADDR:
259 		if ((ifp->if_flags & IFF_BROADCAST) == 0)
260 			return (EINVAL);
261 		*((struct sockaddr_in *)&ifr->ifr_dstaddr) = ia->ia_broadaddr;
262 		break;
263 
264 	case SIOCGIFDSTADDR:
265 		if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
266 			return (EINVAL);
267 		*((struct sockaddr_in *)&ifr->ifr_dstaddr) = ia->ia_dstaddr;
268 		break;
269 
270 	case SIOCGIFNETMASK:
271 		*((struct sockaddr_in *)&ifr->ifr_addr) = ia->ia_sockmask;
272 		break;
273 
274 	case SIOCSIFDSTADDR:
275 		if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
276 			return (EINVAL);
277 		oldaddr = ia->ia_dstaddr;
278 		ia->ia_dstaddr = *(struct sockaddr_in *)&ifr->ifr_dstaddr;
279 		if (ifp->if_ioctl && (error = (*ifp->if_ioctl)
280 					(ifp, SIOCSIFDSTADDR, (caddr_t)ia))) {
281 			ia->ia_dstaddr = oldaddr;
282 			return (error);
283 		}
284 		if (ia->ia_flags & IFA_ROUTE) {
285 			ia->ia_ifa.ifa_dstaddr = (struct sockaddr *)&oldaddr;
286 			rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST);
287 			ia->ia_ifa.ifa_dstaddr =
288 					(struct sockaddr *)&ia->ia_dstaddr;
289 			rtinit(&(ia->ia_ifa), (int)RTM_ADD, RTF_HOST|RTF_UP);
290 		}
291 		break;
292 
293 	case SIOCSIFBRDADDR:
294 		if ((ifp->if_flags & IFF_BROADCAST) == 0)
295 			return (EINVAL);
296 		ia->ia_broadaddr = *(struct sockaddr_in *)&ifr->ifr_broadaddr;
297 		break;
298 
299 	case SIOCSIFADDR:
300 		return (in_ifinit(ifp, ia,
301 		    (struct sockaddr_in *) &ifr->ifr_addr, 1));
302 
303 	case SIOCSIFNETMASK:
304 		i = ifra->ifra_addr.sin_addr.s_addr;
305 		ia->ia_subnetmask = ntohl(ia->ia_sockmask.sin_addr.s_addr = i);
306 		break;
307 
308 	case SIOCAIFADDR:
309 		maskIsNew = 0;
310 		hostIsNew = 1;
311 		error = 0;
312 		if (ia->ia_addr.sin_family == AF_INET) {
313 			if (ifra->ifra_addr.sin_len == 0) {
314 				ifra->ifra_addr = ia->ia_addr;
315 				hostIsNew = 0;
316 			} else if (ifra->ifra_addr.sin_addr.s_addr ==
317 					       ia->ia_addr.sin_addr.s_addr)
318 				hostIsNew = 0;
319 		}
320 		if (ifra->ifra_mask.sin_len) {
321 			in_ifscrub(ifp, ia);
322 			ia->ia_sockmask = ifra->ifra_mask;
323 			ia->ia_subnetmask =
324 			     ntohl(ia->ia_sockmask.sin_addr.s_addr);
325 			maskIsNew = 1;
326 		}
327 		if ((ifp->if_flags & IFF_POINTOPOINT) &&
328 		    (ifra->ifra_dstaddr.sin_family == AF_INET)) {
329 			in_ifscrub(ifp, ia);
330 			ia->ia_dstaddr = ifra->ifra_dstaddr;
331 			maskIsNew  = 1; /* We lie; but the effect's the same */
332 		}
333 		if (ifra->ifra_addr.sin_family == AF_INET &&
334 		    (hostIsNew || maskIsNew))
335 			error = in_ifinit(ifp, ia, &ifra->ifra_addr, 0);
336 		if ((ifp->if_flags & IFF_BROADCAST) &&
337 		    (ifra->ifra_broadaddr.sin_family == AF_INET))
338 			ia->ia_broadaddr = ifra->ifra_broadaddr;
339 		return (error);
340 
341 	case SIOCDIFADDR:
342 		in_ifscrub(ifp, ia);
343 		/*
344 		 * Protect from ipintr() traversing address list
345 		 * while we're modifying it.
346 		 */
347 		s = splnet();
348 
349 		ifa = &ia->ia_ifa;
350 		TAILQ_REMOVE(&ifp->if_addrhead, ifa, ifa_link);
351 		oia = ia;
352 		TAILQ_REMOVE(&in_ifaddrhead, oia, ia_link);
353 		IFAFREE(&oia->ia_ifa);
354 		splx(s);
355 		break;
356 
357 	default:
358 		if (ifp == 0 || ifp->if_ioctl == 0)
359 			return (EOPNOTSUPP);
360 		return ((*ifp->if_ioctl)(ifp, cmd, data));
361 	}
362 	return (0);
363 }
364 
365 /*
366  * Delete any existing route for an interface.
367  */
368 void
369 in_ifscrub(ifp, ia)
370 	register struct ifnet *ifp;
371 	register struct in_ifaddr *ia;
372 {
373 
374 	if ((ia->ia_flags & IFA_ROUTE) == 0)
375 		return;
376 	if (ifp->if_flags & (IFF_LOOPBACK|IFF_POINTOPOINT))
377 		rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST);
378 	else
379 		rtinit(&(ia->ia_ifa), (int)RTM_DELETE, 0);
380 	ia->ia_flags &= ~IFA_ROUTE;
381 }
382 
383 /*
384  * Initialize an interface's internet address
385  * and routing table entry.
386  */
387 static int
388 in_ifinit(ifp, ia, sin, scrub)
389 	register struct ifnet *ifp;
390 	register struct in_ifaddr *ia;
391 	struct sockaddr_in *sin;
392 	int scrub;
393 {
394 	register u_long i = ntohl(sin->sin_addr.s_addr);
395 	struct sockaddr_in oldaddr;
396 	int s = splimp(), flags = RTF_UP, error;
397 
398 	oldaddr = ia->ia_addr;
399 	ia->ia_addr = *sin;
400 	/*
401 	 * Give the interface a chance to initialize
402 	 * if this is its first address,
403 	 * and to validate the address if necessary.
404 	 */
405 	if (ifp->if_ioctl &&
406 	    (error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia))) {
407 		splx(s);
408 		ia->ia_addr = oldaddr;
409 		return (error);
410 	}
411 	splx(s);
412 	if (scrub) {
413 		ia->ia_ifa.ifa_addr = (struct sockaddr *)&oldaddr;
414 		in_ifscrub(ifp, ia);
415 		ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
416 	}
417 	if (IN_CLASSA(i))
418 		ia->ia_netmask = IN_CLASSA_NET;
419 	else if (IN_CLASSB(i))
420 		ia->ia_netmask = IN_CLASSB_NET;
421 	else
422 		ia->ia_netmask = IN_CLASSC_NET;
423 	/*
424 	 * The subnet mask usually includes at least the standard network part,
425 	 * but may may be smaller in the case of supernetting.
426 	 * If it is set, we believe it.
427 	 */
428 	if (ia->ia_subnetmask == 0) {
429 		ia->ia_subnetmask = ia->ia_netmask;
430 		ia->ia_sockmask.sin_addr.s_addr = htonl(ia->ia_subnetmask);
431 	} else
432 		ia->ia_netmask &= ia->ia_subnetmask;
433 	ia->ia_net = i & ia->ia_netmask;
434 	ia->ia_subnet = i & ia->ia_subnetmask;
435 	in_socktrim(&ia->ia_sockmask);
436 	/*
437 	 * Add route for the network.
438 	 */
439 	ia->ia_ifa.ifa_metric = ifp->if_metric;
440 	if (ifp->if_flags & IFF_BROADCAST) {
441 		ia->ia_broadaddr.sin_addr.s_addr =
442 			htonl(ia->ia_subnet | ~ia->ia_subnetmask);
443 		ia->ia_netbroadcast.s_addr =
444 			htonl(ia->ia_net | ~ ia->ia_netmask);
445 	} else if (ifp->if_flags & IFF_LOOPBACK) {
446 		ia->ia_ifa.ifa_dstaddr = ia->ia_ifa.ifa_addr;
447 		flags |= RTF_HOST;
448 	} else if (ifp->if_flags & IFF_POINTOPOINT) {
449 		if (ia->ia_dstaddr.sin_family != AF_INET)
450 			return (0);
451 		flags |= RTF_HOST;
452 	}
453 	if ((error = rtinit(&(ia->ia_ifa), (int)RTM_ADD, flags)) == 0)
454 		ia->ia_flags |= IFA_ROUTE;
455 
456 	/*
457 	 * If the interface supports multicast, join the "all hosts"
458 	 * multicast group on that interface.
459 	 */
460 	if (ifp->if_flags & IFF_MULTICAST) {
461 		struct in_addr addr;
462 
463 		addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
464 		in_addmulti(&addr, ifp);
465 	}
466 	return (error);
467 }
468 
469 
470 /*
471  * Return 1 if the address might be a local broadcast address.
472  */
473 int
474 in_broadcast(in, ifp)
475 	struct in_addr in;
476         struct ifnet *ifp;
477 {
478 	register struct ifaddr *ifa;
479 	u_long t;
480 
481 	if (in.s_addr == INADDR_BROADCAST ||
482 	    in.s_addr == INADDR_ANY)
483 		return 1;
484 	if ((ifp->if_flags & IFF_BROADCAST) == 0)
485 		return 0;
486 	t = ntohl(in.s_addr);
487 	/*
488 	 * Look through the list of addresses for a match
489 	 * with a broadcast address.
490 	 */
491 #define ia ((struct in_ifaddr *)ifa)
492 	for (ifa = ifp->if_addrhead.tqh_first; ifa;
493 	     ifa = ifa->ifa_link.tqe_next)
494 		if (ifa->ifa_addr->sa_family == AF_INET &&
495 		    (in.s_addr == ia->ia_broadaddr.sin_addr.s_addr ||
496 		     in.s_addr == ia->ia_netbroadcast.s_addr ||
497 		     /*
498 		      * Check for old-style (host 0) broadcast.
499 		      */
500 		     t == ia->ia_subnet || t == ia->ia_net) &&
501 		     /*
502 		      * Check for an all one subnetmask. These
503 		      * only exist when an interface gets a secondary
504 		      * address.
505 		      */
506 		     ia->ia_subnetmask != (u_long)0xffffffff)
507 			    return 1;
508 	return (0);
509 #undef ia
510 }
511 /*
512  * Add an address to the list of IP multicast addresses for a given interface.
513  */
514 struct in_multi *
515 in_addmulti(ap, ifp)
516 	register struct in_addr *ap;
517 	register struct ifnet *ifp;
518 {
519 	register struct in_multi *inm;
520 	int error;
521 	struct sockaddr_in sin;
522 	struct ifmultiaddr *ifma;
523 	int s = splnet();
524 
525 	/*
526 	 * Call generic routine to add membership or increment
527 	 * refcount.  It wants addresses in the form of a sockaddr,
528 	 * so we build one here (being careful to zero the unused bytes).
529 	 */
530 	bzero(&sin, sizeof sin);
531 	sin.sin_family = AF_INET;
532 	sin.sin_len = sizeof sin;
533 	sin.sin_addr = *ap;
534 	error = if_addmulti(ifp, (struct sockaddr *)&sin, &ifma);
535 	if (error) {
536 		splx(s);
537 		return 0;
538 	}
539 
540 	/*
541 	 * If ifma->ifma_protospec is null, then if_addmulti() created
542 	 * a new record.  Otherwise, we are done.
543 	 */
544 	if (ifma->ifma_protospec != 0)
545 		return ifma->ifma_protospec;
546 
547 	/* XXX - if_addmulti uses M_WAITOK.  Can this really be called
548 	   at interrupt time?  If so, need to fix if_addmulti. XXX */
549 	inm = (struct in_multi *)malloc(sizeof(*inm), M_IPMADDR, M_NOWAIT);
550 	if (inm == NULL) {
551 		splx(s);
552 		return (NULL);
553 	}
554 
555 	bzero(inm, sizeof *inm);
556 	inm->inm_addr = *ap;
557 	inm->inm_ifp = ifp;
558 	inm->inm_ifma = ifma;
559 	ifma->ifma_protospec = inm;
560 	LIST_INSERT_HEAD(&in_multihead, inm, inm_link);
561 
562 	/*
563 	 * Let IGMP know that we have joined a new IP multicast group.
564 	 */
565 	igmp_joingroup(inm);
566 	splx(s);
567 	return (inm);
568 }
569 
570 /*
571  * Delete a multicast address record.
572  */
573 void
574 in_delmulti(inm)
575 	register struct in_multi *inm;
576 {
577 	struct ifmultiaddr *ifma = inm->inm_ifma;
578 	int s = splnet();
579 
580 	if (ifma->ifma_refcount == 1) {
581 		/*
582 		 * No remaining claims to this record; let IGMP know that
583 		 * we are leaving the multicast group.
584 		 */
585 		igmp_leavegroup(inm);
586 		ifma->ifma_protospec = 0;
587 		LIST_REMOVE(inm, inm_link);
588 		free(inm, M_IPMADDR);
589 	}
590 	/* XXX - should be separate API for when we have an ifma? */
591 	if_delmulti(ifma->ifma_ifp, ifma->ifma_addr);
592 	splx(s);
593 }
594