arp.c revision 13389 
1/*
2 * sys-bsd.c - System-dependent procedures for setting up
3 * PPP interfaces on bsd-4.4-ish systems (including 386BSD, NetBSD, etc.)
4 *
5 * Copyright (c) 1989 Carnegie Mellon University.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by Carnegie Mellon University.  The name of the
14 * University may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 * $Id: arp.c,v 1.3 1996/01/10 21:27:35 phk Exp $
21 *
22 */
23
24/*
25 * TODO:
26 */
27
28#include <sys/ioctl.h>
29#include <sys/types.h>
30#include <sys/uio.h>
31#include <sys/socket.h>
32#include <sys/time.h>
33#include <sys/errno.h>
34#include <unistd.h>
35#include <string.h>
36
37#include <net/if.h>
38#include <net/route.h>
39#include <net/if_dl.h>
40#include <netinet/in.h>
41#include <stdio.h>
42#include <fcntl.h>
43#ifdef __bsdi__
44#include <kvm.h>
45#endif
46#include <net/if_types.h>
47#include <netinet/in_var.h>
48#include <netinet/if_ether.h>
49#include "log.h"
50
51#if RTM_VERSION >= 3
52#include <netinet/if_ether.h>
53#endif
54
55static int rtm_seq;
56
57static int get_ether_addr __P((int, u_long, struct sockaddr_dl *));
58
59#define BCOPY(s, d, l)		memcpy(d, s, l)
60#define BZERO(s, n)		memset(s, 0, n)
61/*
62 * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
63 * if it exists.
64 */
65#define SET_SA_FAMILY(addr, family)		\
66    BZERO((char *) &(addr), sizeof(addr));	\
67    addr.sa_family = (family); 			\
68    addr.sa_len = sizeof(addr);
69
70
71#if RTM_VERSION >= 3
72
73/*
74 * sifproxyarp - Make a proxy ARP entry for the peer.
75 */
76static struct {
77    struct rt_msghdr		hdr;
78    struct sockaddr_inarp	dst;
79    struct sockaddr_dl		hwa;
80    char			extra[128];
81} arpmsg;
82
83static int arpmsg_valid;
84
85int
86sifproxyarp(unit, hisaddr)
87    int unit;
88    u_long hisaddr;
89{
90    int routes;
91
92    /*
93     * Get the hardware address of an interface on the same subnet
94     * as our local address.
95     */
96    memset(&arpmsg, 0, sizeof(arpmsg));
97    if (!get_ether_addr(unit, hisaddr, &arpmsg.hwa)) {
98	logprintf("Cannot determine ethernet address for proxy ARP\n");
99	return 0;
100    }
101
102    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
103	logprintf("sifproxyarp: opening routing socket: \n");
104	return 0;
105    }
106
107    arpmsg.hdr.rtm_type = RTM_ADD;
108    arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
109    arpmsg.hdr.rtm_version = RTM_VERSION;
110    arpmsg.hdr.rtm_seq = ++rtm_seq;
111    arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
112    arpmsg.hdr.rtm_inits = RTV_EXPIRE;
113    arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
114    arpmsg.dst.sin_family = AF_INET;
115    arpmsg.dst.sin_addr.s_addr = hisaddr;
116    arpmsg.dst.sin_other = SIN_PROXY;
117
118    arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
119	+ arpmsg.hwa.sdl_len;
120    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
121	logprintf("add proxy arp entry: \n");
122	close(routes);
123	return 0;
124    }
125
126    close(routes);
127    arpmsg_valid = 1;
128    return 1;
129}
130
131/*
132 * cifproxyarp - Delete the proxy ARP entry for the peer.
133 */
134int
135cifproxyarp(unit, hisaddr)
136    int unit;
137    u_long hisaddr;
138{
139    int routes;
140
141    if (!arpmsg_valid)
142	return 0;
143    arpmsg_valid = 0;
144
145    arpmsg.hdr.rtm_type = RTM_DELETE;
146    arpmsg.hdr.rtm_seq = ++rtm_seq;
147
148    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
149	logprintf("sifproxyarp: opening routing socket: \n");
150	return 0;
151    }
152
153    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
154	logprintf("delete proxy arp entry: \n");
155	close(routes);
156	return 0;
157    }
158
159    close(routes);
160    return 1;
161}
162
163#else	/* RTM_VERSION */
164
165/*
166 * sifproxyarp - Make a proxy ARP entry for the peer.
167 */
168int
169sifproxyarp(unit, hisaddr)
170    int unit;
171    u_long hisaddr;
172{
173    struct arpreq arpreq;
174    struct {
175	struct sockaddr_dl	sdl;
176	char			space[128];
177    } dls;
178
179    BZERO(&arpreq, sizeof(arpreq));
180
181    /*
182     * Get the hardware address of an interface on the same subnet
183     * as our local address.
184     */
185    if (!get_ether_addr(unit, hisaddr, &dls.sdl)) {
186	LogPrintf(LOG_PHASE, "Cannot determine ethernet address for proxy ARP\n");
187	return 0;
188    }
189
190    arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
191    arpreq.arp_ha.sa_family = AF_UNSPEC;
192    BCOPY(LLADDR(&dls.sdl), arpreq.arp_ha.sa_data, dls.sdl.sdl_alen);
193    SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
194    ((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = hisaddr;
195    arpreq.arp_flags = ATF_PERM | ATF_PUBL;
196    if (ioctl(unit, SIOCSARP, (caddr_t)&arpreq) < 0) {
197	fprintf(stderr, "ioctl(SIOCSARP): \n");
198	return 0;
199    }
200
201    return 1;
202}
203
204/*
205 * cifproxyarp - Delete the proxy ARP entry for the peer.
206 */
207int
208cifproxyarp(unit, hisaddr)
209    int unit;
210    u_long hisaddr;
211{
212    struct arpreq arpreq;
213
214    BZERO(&arpreq, sizeof(arpreq));
215    SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
216    ((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = hisaddr;
217    if (ioctl(unit, SIOCDARP, (caddr_t)&arpreq) < 0) {
218	fprintf(stderr, "ioctl(SIOCDARP): \n");
219	return 0;
220    }
221    return 1;
222}
223#endif	/* RTM_VERSION */
224
225
226/*
227 * get_ether_addr - get the hardware address of an interface on the
228 * the same subnet as ipaddr.
229 */
230#define MAX_IFS		32
231
232int
233get_ether_addr(s, ipaddr, hwaddr)
234    int    s;
235    u_long ipaddr;
236    struct sockaddr_dl *hwaddr;
237{
238    struct ifreq *ifr, *ifend, *ifp;
239    u_long ina, mask;
240    struct sockaddr_dl *dla;
241    struct ifreq ifreq;
242    struct ifconf ifc;
243    struct ifreq ifs[MAX_IFS];
244
245    ifc.ifc_len = sizeof(ifs);
246    ifc.ifc_req = ifs;
247    if (ioctl(s, SIOCGIFCONF, &ifc) < 0) {
248	fprintf(stderr, "ioctl(SIOCGIFCONF): \n");
249	return 0;
250    }
251
252    /*
253     * Scan through looking for an interface with an Internet
254     * address on the same subnet as `ipaddr'.
255     */
256    ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
257    for (ifr = ifc.ifc_req; ifr < ifend; ) {
258	if (ifr->ifr_addr.sa_family == AF_INET) {
259	    ina = ((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr;
260	    strncpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
261	    /*
262	     * Check that the interface is up, and not point-to-point
263	     * or loopback.
264	     */
265	    if (ioctl(s, SIOCGIFFLAGS, &ifreq) < 0)
266		continue;
267	    if ((ifreq.ifr_flags &
268		 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|IFF_LOOPBACK|IFF_NOARP))
269		 != (IFF_UP|IFF_BROADCAST))
270		goto nextif;
271	    /*
272	     * Get its netmask and check that it's on the right subnet.
273	     */
274	    if (ioctl(s, SIOCGIFNETMASK, &ifreq) < 0)
275		continue;
276	    mask = ((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr.s_addr;
277	    if ((ipaddr & mask) != (ina & mask))
278		goto nextif;
279
280	    break;
281	}
282nextif:
283	ifr = (struct ifreq *) ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len);
284    }
285
286    if (ifr >= ifend)
287	return 0;
288    LogPrintf(LOG_PHASE, "found interface %s for proxy arp\n", ifr->ifr_name);
289
290    /*
291     * Now scan through again looking for a link-level address
292     * for this interface.
293     */
294    ifp = ifr;
295    for (ifr = ifc.ifc_req; ifr < ifend; ) {
296	if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0
297	    && ifr->ifr_addr.sa_family == AF_LINK) {
298	    /*
299	     * Found the link-level address - copy it out
300	     */
301	    dla = (struct sockaddr_dl *) &ifr->ifr_addr;
302#ifdef __bsdi__
303	    if (dla->sdl_alen == 0)
304	      kmemgetether(ifr->ifr_name, dla);
305#endif
306	    BCOPY(dla, hwaddr, dla->sdl_len);
307	    return 1;
308	}
309	ifr = (struct ifreq *) ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len);
310    }
311
312    return 0;
313}
314
315#ifdef __bsdi__
316#include <nlist.h>
317
318struct nlist nl[] = {
319#define N_IFNET		0
320	{ "_ifnet" },
321	"",
322};
323
324
325kvm_t *kvmd;
326
327/*
328 * Read kernel memory, return 0 on success.
329 */
330int
331kread(addr, buf, size)
332  u_long addr;
333  char *buf;
334  int size;
335{
336
337	if (kvm_read(kvmd, addr, buf, size) != size) {
338		/* XXX this duplicates kvm_read's error printout */
339		(void)fprintf(stderr, "kvm_read %s\n",
340			kvm_geterr(kvmd));
341		return (-1);
342	}
343	return (0);
344}
345
346kmemgetether(ifname, dlo)
347char *ifname;
348struct sockaddr_dl *dlo;
349{
350  struct ifnet ifnet;
351  int n;
352  u_long addr, ifaddraddr, ifnetfound, ifaddrfound;
353  char name[32];
354  struct sockaddr *sa;
355  char *cp;
356  struct sockaddr_dl *sdl;
357  union {
358	  struct ifaddr ifa;
359	  struct in_ifaddr in;
360  } ifaddr;
361  struct arpcom ac;
362
363  kvmd = kvm_open(NULL, NULL, NULL, O_RDONLY, NULL);
364  if (kvmd) {
365    n = kvm_nlist(kvmd, nl);
366    if (n >= 0) {
367      addr = nl[N_IFNET].n_value;
368      kread(addr, (char *)&addr, sizeof(addr));
369      ifaddraddr = ifnetfound = 0;
370      while (addr || ifaddraddr) {
371	ifnetfound = addr;
372	if (ifaddraddr == 0) {
373	  if (kread(addr, (char *)&ifnet, sizeof(ifnet)) ||
374	      kread((u_long)ifnet.if_name, name, 16))
375		return;
376	  name[15] = 0;
377	  addr = (u_long) ifnet.if_next;
378	  cp = (char *)index(name, '\0');
379	  cp += sprintf(cp, "%d", ifnet.if_unit);
380	  *cp = '\0';
381	  ifaddraddr = (u_long)ifnet.if_addrlist;
382	}
383	ifaddrfound = ifaddraddr;
384	if (ifaddraddr) {
385	  if (kread(ifaddraddr, (char *)&ifaddr, sizeof ifaddr)) {
386	    ifaddraddr = 0;
387	    continue;
388	  }
389#define CP(x) ((char *)(x))
390	  cp = (CP(ifaddr.ifa.ifa_addr) - CP(ifaddraddr)) + CP(&ifaddr);
391	  sa = (struct sockaddr *)cp;
392	  if (sa->sa_family == AF_LINK && strcmp(ifname, name) == 0) {
393	    sdl = (struct sockaddr_dl *)sa;
394	    cp = (char *)LLADDR(sdl);
395	    n = sdl->sdl_alen;
396	    if (ifnet.if_type == IFT_ETHER) {
397		if (n == 0) {
398		  kread(ifnetfound, (char *)&ac, sizeof(ac));
399	    	  cp = (char *)LLADDR(sdl);
400		  bcopy((char *)ac.ac_enaddr, cp, 6);
401		  sdl->sdl_alen = 6;
402		}
403		bcopy(sdl, dlo, sizeof(*sdl));
404		return;
405	    }
406	  }
407	  ifaddraddr = (u_long)ifaddr.ifa.ifa_next;
408	}
409      }
410    }
411  }
412}
413#endif
414
415#ifdef DEBUG
416main()
417{
418    u_long ipaddr;
419    int s;
420
421    s = socket(AF_INET, SOCK_DGRAM, 0);
422    ipaddr = inet_addr("192.168.1.32");
423    sifproxyarp(s, ipaddr);
424    close(s);
425}
426#endif
427