xref: /freebsd/sys/netinet/in.c (revision 380a989b3223d455375b4fae70fd0b9bdd43bafb)
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  *	$Id: in.c,v 1.38 1998/06/07 17:12:13 dfr Exp $
35  */
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/sockio.h>
40 #include <sys/malloc.h>
41 #include <sys/proc.h>
42 #include <sys/socket.h>
43 #include <sys/kernel.h>
44 #include <sys/sysctl.h>
45 
46 #include <net/if.h>
47 #include <net/route.h>
48 
49 #include <netinet/in.h>
50 #include <netinet/in_var.h>
51 
52 #include <netinet/igmp_var.h>
53 
54 static MALLOC_DEFINE(M_IPMADDR, "in_multi", "internet multicast address");
55 
56 static void	in_socktrim __P((struct sockaddr_in *));
57 static int	in_ifinit __P((struct ifnet *,
58 	    struct in_ifaddr *, struct sockaddr_in *, int));
59 
60 static int subnetsarelocal = 0;
61 SYSCTL_INT(_net_inet_ip, OID_AUTO, subnets_are_local, CTLFLAG_RW,
62 	&subnetsarelocal, 0, "");
63 
64 struct in_multihead in_multihead; /* XXX BSS initialization */
65 
66 /*
67  * Return 1 if an internet address is for a ``local'' host
68  * (one to which we have a connection).  If subnetsarelocal
69  * is true, this includes other subnets of the local net.
70  * Otherwise, it includes only the directly-connected (sub)nets.
71  */
72 int
73 in_localaddr(in)
74 	struct in_addr in;
75 {
76 	register u_long i = ntohl(in.s_addr);
77 	register struct in_ifaddr *ia;
78 
79 	if (subnetsarelocal) {
80 		for (ia = in_ifaddrhead.tqh_first; ia;
81 		     ia = ia->ia_link.tqe_next)
82 			if ((i & ia->ia_netmask) == ia->ia_net)
83 				return (1);
84 	} else {
85 		for (ia = in_ifaddrhead.tqh_first; ia;
86 		     ia = ia->ia_link.tqe_next)
87 			if ((i & ia->ia_subnetmask) == ia->ia_subnet)
88 				return (1);
89 	}
90 	return (0);
91 }
92 
93 /*
94  * Determine whether an IP address is in a reserved set of addresses
95  * that may not be forwarded, or whether datagrams to that destination
96  * may be forwarded.
97  */
98 int
99 in_canforward(in)
100 	struct in_addr in;
101 {
102 	register u_long i = ntohl(in.s_addr);
103 	register u_long net;
104 
105 	if (IN_EXPERIMENTAL(i) || IN_MULTICAST(i))
106 		return (0);
107 	if (IN_CLASSA(i)) {
108 		net = i & IN_CLASSA_NET;
109 		if (net == 0 || net == (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))
110 			return (0);
111 	}
112 	return (1);
113 }
114 
115 /*
116  * Trim a mask in a sockaddr
117  */
118 static void
119 in_socktrim(ap)
120 struct sockaddr_in *ap;
121 {
122     register char *cplim = (char *) &ap->sin_addr;
123     register char *cp = (char *) (&ap->sin_addr + 1);
124 
125     ap->sin_len = 0;
126     while (--cp >= cplim)
127         if (*cp) {
128 	    (ap)->sin_len = cp - (char *) (ap) + 1;
129 	    break;
130 	}
131 }
132 
133 static int in_interfaces;	/* number of external internet interfaces */
134 
135 /*
136  * Generic internet control operations (ioctl's).
137  * Ifp is 0 if not an interface-specific ioctl.
138  */
139 /* ARGSUSED */
140 int
141 in_control(so, cmd, data, ifp, p)
142 	struct socket *so;
143 	u_long cmd;
144 	caddr_t data;
145 	register struct ifnet *ifp;
146 	struct proc *p;
147 {
148 	register struct ifreq *ifr = (struct ifreq *)data;
149 	register struct in_ifaddr *ia = 0, *iap;
150 	register struct ifaddr *ifa;
151 	struct in_ifaddr *oia;
152 	struct in_aliasreq *ifra = (struct in_aliasreq *)data;
153 	struct sockaddr_in oldaddr;
154 	int error, hostIsNew, maskIsNew, s;
155 	u_long i;
156 
157 	/*
158 	 * Find address for this interface, if it exists.
159 	 *
160 	 * If an alias address was specified, find that one instead of
161 	 * the first one on the interface.
162 	 */
163 	if (ifp)
164 		for (iap = in_ifaddrhead.tqh_first; iap;
165 		     iap = iap->ia_link.tqe_next)
166 			if (iap->ia_ifp == ifp) {
167 				if (((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr.s_addr ==
168 				    iap->ia_addr.sin_addr.s_addr) {
169 					ia = iap;
170 					break;
171 				} else if (ia == NULL) {
172 					ia = iap;
173 					if (ifr->ifr_addr.sa_family != AF_INET)
174 						break;
175 				}
176 			}
177 
178 	switch (cmd) {
179 
180 	case SIOCAIFADDR:
181 	case SIOCDIFADDR:
182 		if (ifp == 0)
183 			return (EADDRNOTAVAIL);
184 		if (ifra->ifra_addr.sin_family == AF_INET) {
185 			for (oia = ia; ia; ia = ia->ia_link.tqe_next) {
186 				if (ia->ia_ifp == ifp  &&
187 				    ia->ia_addr.sin_addr.s_addr ==
188 				    ifra->ifra_addr.sin_addr.s_addr)
189 					break;
190 			}
191 			if ((ifp->if_flags & IFF_POINTOPOINT)
192 			    && (cmd == SIOCAIFADDR)
193 			    && (ifra->ifra_dstaddr.sin_addr.s_addr
194 				== INADDR_ANY)) {
195 				return EDESTADDRREQ;
196 			}
197 		}
198 		if (cmd == SIOCDIFADDR && ia == 0)
199 			return (EADDRNOTAVAIL);
200 		/* FALLTHROUGH */
201 	case SIOCSIFADDR:
202 	case SIOCSIFNETMASK:
203 	case SIOCSIFDSTADDR:
204 		if (p && (error = suser(p->p_ucred, &p->p_acflag)) != 0)
205 			return error;
206 
207 		if (ifp == 0)
208 			return (EADDRNOTAVAIL);
209 		if (ia == (struct in_ifaddr *)0) {
210 			ia = (struct in_ifaddr *)
211 				malloc(sizeof *ia, M_IFADDR, M_WAITOK);
212 			if (ia == (struct in_ifaddr *)NULL)
213 				return (ENOBUFS);
214 			bzero((caddr_t)ia, sizeof *ia);
215 			/*
216 			 * Protect from ipintr() traversing address list
217 			 * while we're modifying it.
218 			 */
219 			s = splnet();
220 
221 			TAILQ_INSERT_TAIL(&in_ifaddrhead, ia, ia_link);
222 			ifa = &ia->ia_ifa;
223 			TAILQ_INSERT_TAIL(&ifp->if_addrhead, ifa, ifa_link);
224 
225 			ifa->ifa_addr = (struct sockaddr *)&ia->ia_addr;
226 			ifa->ifa_dstaddr = (struct sockaddr *)&ia->ia_dstaddr;
227 			ifa->ifa_netmask = (struct sockaddr *)&ia->ia_sockmask;
228 			ia->ia_sockmask.sin_len = 8;
229 			if (ifp->if_flags & IFF_BROADCAST) {
230 				ia->ia_broadaddr.sin_len = sizeof(ia->ia_addr);
231 				ia->ia_broadaddr.sin_family = AF_INET;
232 			}
233 			ia->ia_ifp = ifp;
234 			if (!(ifp->if_flags & IFF_LOOPBACK))
235 				in_interfaces++;
236 			splx(s);
237 		}
238 		break;
239 
240 	case SIOCSIFBRDADDR:
241 		if (p && (error = suser(p->p_ucred, &p->p_acflag)) != 0)
242 			return error;
243 		/* FALLTHROUGH */
244 
245 	case SIOCGIFADDR:
246 	case SIOCGIFNETMASK:
247 	case SIOCGIFDSTADDR:
248 	case SIOCGIFBRDADDR:
249 		if (ia == (struct in_ifaddr *)0)
250 			return (EADDRNOTAVAIL);
251 		break;
252 	}
253 	switch (cmd) {
254 
255 	case SIOCGIFADDR:
256 		*((struct sockaddr_in *)&ifr->ifr_addr) = ia->ia_addr;
257 		break;
258 
259 	case SIOCGIFBRDADDR:
260 		if ((ifp->if_flags & IFF_BROADCAST) == 0)
261 			return (EINVAL);
262 		*((struct sockaddr_in *)&ifr->ifr_dstaddr) = ia->ia_broadaddr;
263 		break;
264 
265 	case SIOCGIFDSTADDR:
266 		if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
267 			return (EINVAL);
268 		*((struct sockaddr_in *)&ifr->ifr_dstaddr) = ia->ia_dstaddr;
269 		break;
270 
271 	case SIOCGIFNETMASK:
272 		*((struct sockaddr_in *)&ifr->ifr_addr) = ia->ia_sockmask;
273 		break;
274 
275 	case SIOCSIFDSTADDR:
276 		if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
277 			return (EINVAL);
278 		oldaddr = ia->ia_dstaddr;
279 		ia->ia_dstaddr = *(struct sockaddr_in *)&ifr->ifr_dstaddr;
280 		if (ifp->if_ioctl && (error = (*ifp->if_ioctl)
281 					(ifp, SIOCSIFDSTADDR, (caddr_t)ia))) {
282 			ia->ia_dstaddr = oldaddr;
283 			return (error);
284 		}
285 		if (ia->ia_flags & IFA_ROUTE) {
286 			ia->ia_ifa.ifa_dstaddr = (struct sockaddr *)&oldaddr;
287 			rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST);
288 			ia->ia_ifa.ifa_dstaddr =
289 					(struct sockaddr *)&ia->ia_dstaddr;
290 			rtinit(&(ia->ia_ifa), (int)RTM_ADD, RTF_HOST|RTF_UP);
291 		}
292 		break;
293 
294 	case SIOCSIFBRDADDR:
295 		if ((ifp->if_flags & IFF_BROADCAST) == 0)
296 			return (EINVAL);
297 		ia->ia_broadaddr = *(struct sockaddr_in *)&ifr->ifr_broadaddr;
298 		break;
299 
300 	case SIOCSIFADDR:
301 		return (in_ifinit(ifp, ia,
302 		    (struct sockaddr_in *) &ifr->ifr_addr, 1));
303 
304 	case SIOCSIFNETMASK:
305 		i = ifra->ifra_addr.sin_addr.s_addr;
306 		ia->ia_subnetmask = ntohl(ia->ia_sockmask.sin_addr.s_addr = i);
307 		break;
308 
309 	case SIOCAIFADDR:
310 		maskIsNew = 0;
311 		hostIsNew = 1;
312 		error = 0;
313 		if (ia->ia_addr.sin_family == AF_INET) {
314 			if (ifra->ifra_addr.sin_len == 0) {
315 				ifra->ifra_addr = ia->ia_addr;
316 				hostIsNew = 0;
317 			} else if (ifra->ifra_addr.sin_addr.s_addr ==
318 					       ia->ia_addr.sin_addr.s_addr)
319 				hostIsNew = 0;
320 		}
321 		if (ifra->ifra_mask.sin_len) {
322 			in_ifscrub(ifp, ia);
323 			ia->ia_sockmask = ifra->ifra_mask;
324 			ia->ia_subnetmask =
325 			     ntohl(ia->ia_sockmask.sin_addr.s_addr);
326 			maskIsNew = 1;
327 		}
328 		if ((ifp->if_flags & IFF_POINTOPOINT) &&
329 		    (ifra->ifra_dstaddr.sin_family == AF_INET)) {
330 			in_ifscrub(ifp, ia);
331 			ia->ia_dstaddr = ifra->ifra_dstaddr;
332 			maskIsNew  = 1; /* We lie; but the effect's the same */
333 		}
334 		if (ifra->ifra_addr.sin_family == AF_INET &&
335 		    (hostIsNew || maskIsNew))
336 			error = in_ifinit(ifp, ia, &ifra->ifra_addr, 0);
337 		if ((ifp->if_flags & IFF_BROADCAST) &&
338 		    (ifra->ifra_broadaddr.sin_family == AF_INET))
339 			ia->ia_broadaddr = ifra->ifra_broadaddr;
340 		return (error);
341 
342 	case SIOCDIFADDR:
343 		in_ifscrub(ifp, ia);
344 		/*
345 		 * Protect from ipintr() traversing address list
346 		 * while we're modifying it.
347 		 */
348 		s = splnet();
349 
350 		ifa = &ia->ia_ifa;
351 		TAILQ_REMOVE(&ifp->if_addrhead, ifa, ifa_link);
352 		oia = ia;
353 		TAILQ_REMOVE(&in_ifaddrhead, oia, ia_link);
354 		IFAFREE(&oia->ia_ifa);
355 		splx(s);
356 		break;
357 
358 	default:
359 		if (ifp == 0 || ifp->if_ioctl == 0)
360 			return (EOPNOTSUPP);
361 		return ((*ifp->if_ioctl)(ifp, cmd, data));
362 	}
363 	return (0);
364 }
365 
366 /*
367  * Delete any existing route for an interface.
368  */
369 void
370 in_ifscrub(ifp, ia)
371 	register struct ifnet *ifp;
372 	register struct in_ifaddr *ia;
373 {
374 
375 	if ((ia->ia_flags & IFA_ROUTE) == 0)
376 		return;
377 	if (ifp->if_flags & (IFF_LOOPBACK|IFF_POINTOPOINT))
378 		rtinit(&(ia->ia_ifa), (int)RTM_DELETE, RTF_HOST);
379 	else
380 		rtinit(&(ia->ia_ifa), (int)RTM_DELETE, 0);
381 	ia->ia_flags &= ~IFA_ROUTE;
382 }
383 
384 /*
385  * Initialize an interface's internet address
386  * and routing table entry.
387  */
388 static int
389 in_ifinit(ifp, ia, sin, scrub)
390 	register struct ifnet *ifp;
391 	register struct in_ifaddr *ia;
392 	struct sockaddr_in *sin;
393 	int scrub;
394 {
395 	register u_long i = ntohl(sin->sin_addr.s_addr);
396 	struct sockaddr_in oldaddr;
397 	int s = splimp(), flags = RTF_UP, error;
398 
399 	oldaddr = ia->ia_addr;
400 	ia->ia_addr = *sin;
401 	/*
402 	 * Give the interface a chance to initialize
403 	 * if this is its first address,
404 	 * and to validate the address if necessary.
405 	 */
406 	if (ifp->if_ioctl &&
407 	    (error = (*ifp->if_ioctl)(ifp, SIOCSIFADDR, (caddr_t)ia))) {
408 		splx(s);
409 		ia->ia_addr = oldaddr;
410 		return (error);
411 	}
412 	splx(s);
413 	if (scrub) {
414 		ia->ia_ifa.ifa_addr = (struct sockaddr *)&oldaddr;
415 		in_ifscrub(ifp, ia);
416 		ia->ia_ifa.ifa_addr = (struct sockaddr *)&ia->ia_addr;
417 	}
418 	if (IN_CLASSA(i))
419 		ia->ia_netmask = IN_CLASSA_NET;
420 	else if (IN_CLASSB(i))
421 		ia->ia_netmask = IN_CLASSB_NET;
422 	else
423 		ia->ia_netmask = IN_CLASSC_NET;
424 	/*
425 	 * The subnet mask usually includes at least the standard network part,
426 	 * but may may be smaller in the case of supernetting.
427 	 * If it is set, we believe it.
428 	 */
429 	if (ia->ia_subnetmask == 0) {
430 		ia->ia_subnetmask = ia->ia_netmask;
431 		ia->ia_sockmask.sin_addr.s_addr = htonl(ia->ia_subnetmask);
432 	} else
433 		ia->ia_netmask &= ia->ia_subnetmask;
434 	ia->ia_net = i & ia->ia_netmask;
435 	ia->ia_subnet = i & ia->ia_subnetmask;
436 	in_socktrim(&ia->ia_sockmask);
437 	/*
438 	 * Add route for the network.
439 	 */
440 	ia->ia_ifa.ifa_metric = ifp->if_metric;
441 	if (ifp->if_flags & IFF_BROADCAST) {
442 		ia->ia_broadaddr.sin_addr.s_addr =
443 			htonl(ia->ia_subnet | ~ia->ia_subnetmask);
444 		ia->ia_netbroadcast.s_addr =
445 			htonl(ia->ia_net | ~ ia->ia_netmask);
446 	} else if (ifp->if_flags & IFF_LOOPBACK) {
447 		ia->ia_ifa.ifa_dstaddr = ia->ia_ifa.ifa_addr;
448 		flags |= RTF_HOST;
449 	} else if (ifp->if_flags & IFF_POINTOPOINT) {
450 		if (ia->ia_dstaddr.sin_family != AF_INET)
451 			return (0);
452 		flags |= RTF_HOST;
453 	}
454 	if ((error = rtinit(&(ia->ia_ifa), (int)RTM_ADD, flags)) == 0)
455 		ia->ia_flags |= IFA_ROUTE;
456 
457 	/*
458 	 * If the interface supports multicast, join the "all hosts"
459 	 * multicast group on that interface.
460 	 */
461 	if (ifp->if_flags & IFF_MULTICAST) {
462 		struct in_addr addr;
463 
464 		addr.s_addr = htonl(INADDR_ALLHOSTS_GROUP);
465 		in_addmulti(&addr, ifp);
466 	}
467 	return (error);
468 }
469 
470 
471 /*
472  * Return 1 if the address might be a local broadcast address.
473  */
474 int
475 in_broadcast(in, ifp)
476 	struct in_addr in;
477         struct ifnet *ifp;
478 {
479 	register struct ifaddr *ifa;
480 	u_long t;
481 
482 	if (in.s_addr == INADDR_BROADCAST ||
483 	    in.s_addr == INADDR_ANY)
484 		return 1;
485 	if ((ifp->if_flags & IFF_BROADCAST) == 0)
486 		return 0;
487 	t = ntohl(in.s_addr);
488 	/*
489 	 * Look through the list of addresses for a match
490 	 * with a broadcast address.
491 	 */
492 #define ia ((struct in_ifaddr *)ifa)
493 	for (ifa = ifp->if_addrhead.tqh_first; ifa;
494 	     ifa = ifa->ifa_link.tqe_next)
495 		if (ifa->ifa_addr->sa_family == AF_INET &&
496 		    (in.s_addr == ia->ia_broadaddr.sin_addr.s_addr ||
497 		     in.s_addr == ia->ia_netbroadcast.s_addr ||
498 		     /*
499 		      * Check for old-style (host 0) broadcast.
500 		      */
501 		     t == ia->ia_subnet || t == ia->ia_net) &&
502 		     /*
503 		      * Check for an all one subnetmask. These
504 		      * only exist when an interface gets a secondary
505 		      * address.
506 		      */
507 		     ia->ia_subnetmask != (u_long)0xffffffff)
508 			    return 1;
509 	return (0);
510 #undef ia
511 }
512 /*
513  * Add an address to the list of IP multicast addresses for a given interface.
514  */
515 struct in_multi *
516 in_addmulti(ap, ifp)
517 	register struct in_addr *ap;
518 	register struct ifnet *ifp;
519 {
520 	register struct in_multi *inm;
521 	int error;
522 	struct sockaddr_in sin;
523 	struct ifmultiaddr *ifma;
524 	int s = splnet();
525 
526 	/*
527 	 * Call generic routine to add membership or increment
528 	 * refcount.  It wants addresses in the form of a sockaddr,
529 	 * so we build one here (being careful to zero the unused bytes).
530 	 */
531 	bzero(&sin, sizeof sin);
532 	sin.sin_family = AF_INET;
533 	sin.sin_len = sizeof sin;
534 	sin.sin_addr = *ap;
535 	error = if_addmulti(ifp, (struct sockaddr *)&sin, &ifma);
536 	if (error) {
537 		splx(s);
538 		return 0;
539 	}
540 
541 	/*
542 	 * If ifma->ifma_protospec is null, then if_addmulti() created
543 	 * a new record.  Otherwise, we are done.
544 	 */
545 	if (ifma->ifma_protospec != 0)
546 		return ifma->ifma_protospec;
547 
548 	/* XXX - if_addmulti uses M_WAITOK.  Can this really be called
549 	   at interrupt time?  If so, need to fix if_addmulti. XXX */
550 	inm = (struct in_multi *)malloc(sizeof(*inm), M_IPMADDR, M_NOWAIT);
551 	if (inm == NULL) {
552 		splx(s);
553 		return (NULL);
554 	}
555 
556 	bzero(inm, sizeof *inm);
557 	inm->inm_addr = *ap;
558 	inm->inm_ifp = ifp;
559 	inm->inm_ifma = ifma;
560 	ifma->ifma_protospec = inm;
561 	LIST_INSERT_HEAD(&in_multihead, inm, inm_link);
562 
563 	/*
564 	 * Let IGMP know that we have joined a new IP multicast group.
565 	 */
566 	igmp_joingroup(inm);
567 	splx(s);
568 	return (inm);
569 }
570 
571 /*
572  * Delete a multicast address record.
573  */
574 void
575 in_delmulti(inm)
576 	register struct in_multi *inm;
577 {
578 	struct ifmultiaddr *ifma = inm->inm_ifma;
579 	int s = splnet();
580 
581 	if (ifma->ifma_refcount == 1) {
582 		/*
583 		 * No remaining claims to this record; let IGMP know that
584 		 * we are leaving the multicast group.
585 		 */
586 		igmp_leavegroup(inm);
587 		ifma->ifma_protospec = 0;
588 		LIST_REMOVE(inm, inm_link);
589 		free(inm, M_IPMADDR);
590 	}
591 	/* XXX - should be separate API for when we have an ifma? */
592 	if_delmulti(ifma->ifma_ifp, ifma->ifma_addr);
593 	splx(s);
594 }
595