1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
|
/* $OpenBSD: dhcrelay.c,v 1.32 2009/09/03 11:56:49 reyk Exp $ */
/*
* Copyright (c) 2004 Henning Brauer <henning@cvs.openbsd.org>
* Copyright (c) 1997, 1998, 1999 The Internet Software Consortium.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of The Internet Software Consortium nor the names
* of its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This software has been written for the Internet Software Consortium
* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
* Enterprises. To learn more about the Internet Software Consortium,
* see ``http://www.vix.com/isc''. To learn more about Vixie
* Enterprises, see ``http://www.vix.com''.
*/
#include "dhcpd.h"
void usage(void);
void relay(struct interface_info *, struct dhcp_packet *, int,
unsigned int, struct iaddr, struct hardware *);
char *print_hw_addr(int, int, unsigned char *);
void got_response(struct protocol *);
ssize_t relay_agentinfo(struct interface_info *, struct dhcp_packet *,
size_t, struct in_addr *, struct in_addr *);
time_t cur_time;
int log_perror = 1;
u_int16_t server_port;
u_int16_t client_port;
int log_priority;
struct interface_info *interfaces = NULL;
int server_fd;
int oflag;
struct server_list {
struct server_list *next;
struct sockaddr_in to;
int fd;
} *servers;
int
main(int argc, char *argv[])
{
int ch, no_daemon = 0, opt;
extern char *__progname;
struct server_list *sp = NULL;
struct passwd *pw;
struct sockaddr_in laddr;
/* Initially, log errors to stderr as well as to syslogd. */
openlog(__progname, LOG_NDELAY, DHCPD_LOG_FACILITY);
setlogmask(LOG_UPTO(LOG_INFO));
while ((ch = getopt(argc, argv, "adi:o")) != -1) {
switch (ch) {
case 'd':
no_daemon = 1;
break;
case 'i':
if (interfaces != NULL)
usage();
if ((interfaces = calloc(1,
sizeof(struct interface_info))) == NULL)
error("calloc");
strlcpy(interfaces->name, optarg,
sizeof(interfaces->name));
break;
case 'o':
/* add the relay agent information option */
oflag++;
break;
default:
usage();
/* not reached */
}
}
argc -= optind;
argv += optind;
if (argc < 1)
usage();
while (argc > 0) {
struct hostent *he;
struct in_addr ia, *iap = NULL;
if (inet_aton(argv[0], &ia))
iap = &ia;
else {
he = gethostbyname(argv[0]);
if (!he)
warning("%s: host unknown", argv[0]);
else
iap = ((struct in_addr *)he->h_addr_list[0]);
}
if (iap) {
if ((sp = calloc(1, sizeof *sp)) == NULL)
error("calloc");
sp->next = servers;
servers = sp;
memcpy(&sp->to.sin_addr, iap, sizeof *iap);
}
argc--;
argv++;
}
if (!no_daemon)
log_perror = 0;
if (interfaces == NULL)
error("no interface given");
/* Default DHCP/BOOTP ports. */
server_port = htons(SERVER_PORT);
client_port = htons(CLIENT_PORT);
/* We need at least one server. */
if (!sp)
usage();
discover_interfaces(interfaces);
/* Enable the relay agent option by default for enc0 */
if (interfaces->hw_address.htype == HTYPE_IPSEC_TUNNEL)
oflag++;
bzero(&laddr, sizeof laddr);
laddr.sin_len = sizeof laddr;
laddr.sin_family = AF_INET;
laddr.sin_port = server_port;
laddr.sin_addr.s_addr = interfaces->primary_address.s_addr;
/* Set up the server sockaddrs. */
for (sp = servers; sp; sp = sp->next) {
sp->to.sin_port = server_port;
sp->to.sin_family = AF_INET;
sp->to.sin_len = sizeof sp->to;
sp->fd = socket(AF_INET, SOCK_DGRAM, 0);
if (sp->fd == -1)
error("socket: %m");
opt = 1;
if (setsockopt(sp->fd, SOL_SOCKET, SO_REUSEPORT,
&opt, sizeof(opt)) == -1)
error("setsockopt: %m");
if (bind(sp->fd, (struct sockaddr *)&laddr, sizeof laddr) == -1)
error("bind: %m");
if (connect(sp->fd, (struct sockaddr *)&sp->to,
sizeof sp->to) == -1)
error("connect: %m");
add_protocol("server", sp->fd, got_response, sp);
}
/* Socket used to forward packets to the DHCP server */
if (interfaces->hw_address.htype == HTYPE_IPSEC_TUNNEL) {
laddr.sin_addr.s_addr = INADDR_ANY;
server_fd = socket(AF_INET, SOCK_DGRAM, 0);
if (server_fd == -1)
error("socket: %m");
opt = 1;
if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEPORT,
&opt, sizeof(opt)) == -1)
error("setsockopt: %m");
if (bind(server_fd, (struct sockaddr *)&laddr,
sizeof(laddr)) == -1)
error("bind: %m");
}
tzset();
time(&cur_time);
bootp_packet_handler = relay;
if (!no_daemon)
daemon(0, 0);
if ((pw = getpwnam("_dhcp")) == NULL)
error("user \"_dhcp\" not found");
if (chroot(_PATH_VAREMPTY) == -1)
error("chroot: %m");
if (chdir("/") == -1)
error("chdir(\"/\"): %m");
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
error("can't drop privileges: %m");
dispatch();
/* not reached */
exit(0);
}
void
relay(struct interface_info *ip, struct dhcp_packet *packet, int length,
unsigned int from_port, struct iaddr from, struct hardware *hfrom)
{
struct server_list *sp;
struct sockaddr_in to;
struct hardware hto;
if (packet->hlen > sizeof packet->chaddr) {
note("Discarding packet with invalid hlen.");
return;
}
/* If it's a bootreply, forward it to the client. */
if (packet->op == BOOTREPLY) {
bzero(&to, sizeof(to));
if (!(packet->flags & htons(BOOTP_BROADCAST))) {
to.sin_addr = packet->yiaddr;
to.sin_port = client_port;
} else {
to.sin_addr.s_addr = htonl(INADDR_BROADCAST);
to.sin_port = client_port;
}
to.sin_family = AF_INET;
to.sin_len = sizeof to;
/* Set up the hardware destination address. */
hto.hlen = packet->hlen;
if (hto.hlen > sizeof hto.haddr)
hto.hlen = sizeof hto.haddr;
memcpy(hto.haddr, packet->chaddr, hto.hlen);
hto.htype = packet->htype;
if ((length = relay_agentinfo(interfaces,
packet, length, NULL, &to.sin_addr)) == -1) {
note("ingnoring BOOTREPLY with invalid "
"relay agent information");
return;
}
if (send_packet(interfaces, packet, length,
interfaces->primary_address, &to, &hto) != -1)
debug("forwarded BOOTREPLY for %s to %s",
print_hw_addr(packet->htype, packet->hlen,
packet->chaddr), inet_ntoa(to.sin_addr));
return;
}
if (ip == NULL) {
note("ignoring non BOOTREPLY from server");
return;
}
/* If giaddr is set on a BOOTREQUEST, ignore it - it's already
been gatewayed. */
if (packet->giaddr.s_addr) {
note("ignoring BOOTREQUEST with giaddr of %s",
inet_ntoa(packet->giaddr));
return;
}
/* Set the giaddr so the server can figure out what net it's
from and so that we can later forward the response to the
correct net. */
packet->giaddr = ip->primary_address;
if ((length = relay_agentinfo(ip, packet, length,
(struct in_addr *)from.iabuf, NULL)) == -1) {
note("ingnoring BOOTREQUEST with invalid "
"relay agent information");
return;
}
/* Otherwise, it's a BOOTREQUEST, so forward it to all the
servers. */
for (sp = servers; sp; sp = sp->next) {
if (send(sp->fd, packet, length, 0) != -1) {
debug("forwarded BOOTREQUEST for %s to %s",
print_hw_addr(packet->htype, packet->hlen,
packet->chaddr), inet_ntoa(sp->to.sin_addr));
}
}
}
void
usage(void)
{
extern char *__progname;
fprintf(stderr, "usage: %s [-do] -i interface server1 [... serverN]\n",
__progname);
exit(1);
}
char *
print_hw_addr(int htype, int hlen, unsigned char *data)
{
static char habuf[49];
char *s = habuf;
int i, j, slen = sizeof(habuf);
if (htype == 0 || hlen == 0) {
bad:
strlcpy(habuf, "<null>", sizeof habuf);
return habuf;
}
for (i = 0; i < hlen; i++) {
j = snprintf(s, slen, "%02x", data[i]);
if (j <= 0 || j >= slen)
goto bad;
j = strlen (s);
s += j;
slen -= (j + 1);
*s++ = ':';
}
*--s = '\0';
return habuf;
}
void
got_response(struct protocol *l)
{
ssize_t result;
struct iaddr ifrom;
union {
/*
* Packet input buffer. Must be as large as largest
* possible MTU.
*/
unsigned char packbuf[4095];
struct dhcp_packet packet;
} u;
struct server_list *sp = l->local;
memset(&u, DHO_END, sizeof(u));
if ((result = recv(l->fd, u.packbuf, sizeof(u), 0)) == -1 &&
errno != ECONNREFUSED) {
/*
* Ignore ECONNREFUSED as to many dhcp server send a bogus
* icmp unreach for every request.
*/
warning("recv failed for %s: %m",
inet_ntoa(sp->to.sin_addr));
return;
}
if (result == -1 && errno == ECONNREFUSED)
return;
if (result == 0)
return;
if (result < BOOTP_MIN_LEN) {
note("Discarding packet with invalid size.");
return;
}
if (bootp_packet_handler) {
ifrom.len = 4;
memcpy(ifrom.iabuf, &sp->to.sin_addr, ifrom.len);
(*bootp_packet_handler)(NULL, &u.packet, result,
sp->to.sin_port, ifrom, NULL);
}
}
ssize_t
relay_agentinfo(struct interface_info *info, struct dhcp_packet *packet,
size_t length, struct in_addr *from, struct in_addr *to)
{
u_int8_t *p;
u_int i, j, railen;
ssize_t optlen, maxlen, grow;
if (!oflag)
return (length);
/* Buffer length vs. received packet length */
maxlen = DHCP_MTU_MAX - DHCP_FIXED_LEN - DHCP_OPTIONS_COOKIE_LEN - 1;
optlen = length - DHCP_FIXED_NON_UDP - DHCP_OPTIONS_COOKIE_LEN;
if (maxlen < 1 || optlen < 1)
return (length);
if (memcmp(packet->options, DHCP_OPTIONS_COOKIE,
DHCP_OPTIONS_COOKIE_LEN) != 0)
return (length);
p = packet->options + DHCP_OPTIONS_COOKIE_LEN;
for (i = 0; i < (u_int)optlen && *p != DHO_END;) {
if (*p == DHO_PAD)
j = 1;
else
j = p[1] + 2;
if ((i + j) > (u_int)optlen) {
warning("truncated dhcp options");
break;
}
/* Revert any other relay agent information */
if (*p == DHO_RELAY_AGENT_INFORMATION) {
if (to != NULL) {
/* Check the relay agent information */
railen = 8 + sizeof(struct in_addr);
if (j >= railen &&
p[1] == (railen - 2) &&
p[2] == RAI_CIRCUIT_ID &&
p[3] == 2 &&
p[4] == (u_int8_t)(info->index << 8) &&
p[5] == (info->index & 0xff) &&
p[6] == RAI_REMOTE_ID &&
p[7] == sizeof(*to))
memcpy(to, p + 8, sizeof(*to));
/* It should be the last option */
memset(p, 0, j);
*p = DHO_END;
} else {
/* Discard invalid option from a client */
if (!packet->giaddr.s_addr)
return (-1);
}
return (length);
}
p += j;
i += j;
if (from != NULL && (*p == DHO_END || (i >= optlen))) {
j = 8 + sizeof(*from);
if ((i + j) > (u_int)maxlen) {
warning("skipping agent information");
break;
}
/* Append the relay agent information if it fits */
p[0] = DHO_RELAY_AGENT_INFORMATION;
p[1] = j - 2;
p[2] = RAI_CIRCUIT_ID;
p[3] = 2;
p[4] = info->index << 8;
p[5] = info->index & 0xff;
p[6] = RAI_REMOTE_ID;
p[7] = sizeof(*from);
memcpy(p + 8, from, sizeof(*from));
/* Do we need to increase the packet length? */
grow = j + 1 - (optlen - i);
if (grow > 0)
length += grow;
p += j;
*p = DHO_END;
break;
}
}
return (length);
}
|