14a9858e059f45977d2682ed1479734d24e3096c
[dragonfly.git] / sbin / dhclient / options.c
1 /*      $OpenBSD: src/sbin/dhclient/options.c,v 1.38 2011/04/17 19:57:23 phessler Exp $ */
2
3 /* DHCP options parsing and reassembly. */
4
5 /*
6  * Copyright (c) 1995, 1996, 1997, 1998 The Internet Software Consortium.
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of The Internet Software Consortium nor the names
19  *    of its contributors may be used to endorse or promote products derived
20  *    from this software without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
23  * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
24  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
25  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
26  * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
27  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
29  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
30  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  *
36  * This software has been written for the Internet Software Consortium
37  * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
38  * Enterprises.  To learn more about the Internet Software Consortium,
39  * see ``http://www.vix.com/isc''.  To learn more about Vixie
40  * Enterprises, see ``http://www.vix.com''.
41  */
42
43 #include <ctype.h>
44
45 #include "dhcpd.h"
46
47 int parse_option_buffer(struct option_data *, unsigned char *, int);
48
49 /*
50  * Parse options out of the specified buffer, storing addresses of
51  * option values in options and setting client->options_valid if
52  * no errors are encountered.
53  */
54 int
55 parse_option_buffer(struct option_data *options, unsigned char *buffer,
56     int length)
57 {
58         unsigned char *s, *t, *end = buffer + length;
59         int len, code;
60
61         for (s = buffer; *s != DHO_END && s < end; ) {
62                 code = s[0];
63
64                 /* Pad options don't have a length - just skip them. */
65                 if (code == DHO_PAD) {
66                         s++;
67                         continue;
68                 }
69
70                 /*
71                  * All options other than DHO_PAD and DHO_END have a
72                  * one-byte length field.
73                  */
74                 if (s + 2 > end)
75                         len = 0;
76                 else
77                         len = s[1];
78
79                 /*
80                  * If the option claims to extend beyond the end of the buffer
81                  * then mark the options buffer bad.
82                  */
83                 if (s + len + 2 > end) {
84                         warning("option %s (%d) larger than buffer.",
85                             dhcp_options[code].name, len);
86                         warning("rejecting bogus offer.");
87                         return (0);
88                 }
89                 /*
90                  * If we haven't seen this option before, just make
91                  * space for it and copy it there.
92                  */
93                 if (!options[code].data) {
94                         if (!(t = calloc(1, len + 1)))
95                                 error("Can't allocate storage for option %s.",
96                                     dhcp_options[code].name);
97                         /*
98                          * Copy and NUL-terminate the option (in case
99                          * it's an ASCII string).
100                          */
101                         memcpy(t, &s[2], len);
102                         t[len] = 0;
103                         options[code].len = len;
104                         options[code].data = t;
105                 } else {
106                         /*
107                          * If it's a repeat, concatenate it to whatever
108                          * we last saw.   This is really only required
109                          * for clients, but what the heck...
110                          */
111                         t = calloc(1, len + options[code].len + 1);
112                         if (!t)
113                                 error("Can't expand storage for option %s.",
114                                     dhcp_options[code].name);
115                         memcpy(t, options[code].data, options[code].len);
116                         memcpy(t + options[code].len, &s[2], len);
117                         options[code].len += len;
118                         t[options[code].len] = 0;
119                         free(options[code].data);
120                         options[code].data = t;
121                 }
122                 s += len + 2;
123         }
124
125         return (1);
126 }
127
128 /*
129  * Copy as many options as fit in buflen bytes of buf. Return the
130  * offset of the start of the last option copied. A caller can check
131  * to see if it's DHO_END to decide if all the options were copied.
132  */
133 int
134 cons_options(unsigned char *buf, const int buflen, struct option_data *options)
135 {
136         int ix, incr, length, bufix, code, lastopt = -1;
137
138         bzero(buf, buflen);
139
140         if (buflen > 3)
141                 memcpy(buf, DHCP_OPTIONS_COOKIE, 4);
142         bufix = 4;
143
144         for (code = DHO_SUBNET_MASK; code < DHO_END; code++) {
145                 if (!options[code].data)
146                         continue;
147
148                 length = options[code].len;
149                 if (bufix + length + 2*((length+254)/255) >= buflen)
150                         return (lastopt);
151
152                 lastopt = bufix;
153                 ix = 0;
154
155                 while (length) {
156                         incr = length > 255 ? 255 : length;
157
158                         buf[bufix++] = code;
159                         buf[bufix++] = incr;
160                         memcpy(buf + bufix, options[code].data + ix, incr);
161
162                         length -= incr;
163                         ix += incr;
164                         bufix += incr;
165                 }
166         }
167
168         if (bufix < buflen) {
169                 buf[bufix] = DHO_END;
170                 lastopt = bufix;
171         }
172
173         return (lastopt);
174 }
175
176 /*
177  * Format the specified option so that a human can easily read it.
178  */
179 char *
180 pretty_print_option(unsigned int code, unsigned char *data, int len,
181     int emit_commas, int emit_quotes)
182 {
183         static char optbuf[32768]; /* XXX */
184         int hunksize = 0, numhunk = -1, numelem = 0;
185         char fmtbuf[32], *op = optbuf;
186         int i, j, k, opleft = sizeof(optbuf);
187         unsigned char *dp = data;
188         struct in_addr foo;
189         char comma;
190
191         /* Code should be between 0 and 255. */
192         if (code > 255)
193                 error("pretty_print_option: bad code %d", code);
194
195         if (emit_commas)
196                 comma = ',';
197         else
198                 comma = ' ';
199
200         /* Figure out the size of the data. */
201         for (i = 0; dhcp_options[code].format[i]; i++) {
202                 if (!numhunk) {
203                         warning("%s: Excess information in format string: %s",
204                             dhcp_options[code].name,
205                             &(dhcp_options[code].format[i]));
206                         break;
207                 }
208                 numelem++;
209                 fmtbuf[i] = dhcp_options[code].format[i];
210                 switch (dhcp_options[code].format[i]) {
211                 case 'A':
212                         --numelem;
213                         fmtbuf[i] = 0;
214                         numhunk = 0;
215                         if (hunksize == 0) {
216                                 warning("%s: no size indicator before A"
217                                     " in format string: %s",
218                                     dhcp_options[code].name,
219                                     dhcp_options[code].format);
220                                 return ("<fmt error>");
221                         }
222                         break;
223                 case 'X':
224                         for (k = 0; k < len; k++)
225                                 if (!isascii(data[k]) ||
226                                     !isprint(data[k]))
227                                         break;
228                         if (k == len) {
229                                 fmtbuf[i] = 't';
230                                 numhunk = -2;
231                         } else {
232                                 fmtbuf[i] = 'x';
233                                 hunksize++;
234                                 comma = ':';
235                                 numhunk = 0;
236                         }
237                         fmtbuf[i + 1] = 0;
238                         break;
239                 case 't':
240                         fmtbuf[i] = 't';
241                         fmtbuf[i + 1] = 0;
242                         numhunk = -2;
243                         break;
244                 case 'I':
245                 case 'l':
246                 case 'L':
247                         hunksize += 4;
248                         break;
249                 case 's':
250                 case 'S':
251                         hunksize += 2;
252                         break;
253                 case 'b':
254                 case 'B':
255                 case 'f':
256                         hunksize++;
257                         break;
258                 case 'e':
259                         break;
260                 default:
261                         warning("%s: garbage in format string: %s",
262                             dhcp_options[code].name,
263                             &(dhcp_options[code].format[i]));
264                         break;
265                 }
266         }
267
268         /* Check for too few bytes... */
269         if (hunksize > len) {
270                 warning("%s: expecting at least %d bytes; got %d",
271                     dhcp_options[code].name, hunksize, len);
272                 return ("<error>");
273         }
274         /* Check for too many bytes... */
275         if (numhunk == -1 && hunksize < len)
276                 warning("%s: %d extra bytes",
277                     dhcp_options[code].name, len - hunksize);
278
279         /* If this is an array, compute its size. */
280         if (!numhunk)
281                 numhunk = len / hunksize;
282         /* See if we got an exact number of hunks. */
283         if (numhunk > 0 && numhunk * hunksize < len)
284                 warning("%s: %d extra bytes at end of array",
285                     dhcp_options[code].name, len - numhunk * hunksize);
286
287         /* A one-hunk array prints the same as a single hunk. */
288         if (numhunk < 0)
289                 numhunk = 1;
290
291         /* Cycle through the array (or hunk) printing the data. */
292         for (i = 0; i < numhunk; i++) {
293                 for (j = 0; j < numelem; j++) {
294                         int opcount;
295                         size_t oplen;
296                         switch (fmtbuf[j]) {
297                         case 't':
298                                 if (emit_quotes) {
299                                         *op++ = '"';
300                                         opleft--;
301                                 }
302                                 for (; dp < data + len; dp++) {
303                                         if (!isascii(*dp) ||
304                                             !isprint(*dp)) {
305                                                 if (dp + 1 != data + len ||
306                                                     *dp != 0) {
307                                                         size_t oplen;
308                                                         snprintf(op, opleft,
309                                                             "\\%03o", *dp);
310                                                         oplen = strlen(op);
311                                                         op += oplen;
312                                                         opleft -= oplen;
313                                                 }
314                                         } else if (*dp == '"' ||
315                                             *dp == '\'' ||
316                                             *dp == '$' ||
317                                             *dp == '`' ||
318                                             *dp == '\\') {
319                                                 *op++ = '\\';
320                                                 *op++ = *dp;
321                                                 opleft -= 2;
322                                         } else {
323                                                 *op++ = *dp;
324                                                 opleft--;
325                                         }
326                                 }
327                                 if (emit_quotes) {
328                                         *op++ = '"';
329                                         opleft--;
330                                 }
331
332                                 *op = 0;
333                                 break;
334                         case 'I':
335                                 foo.s_addr = htonl(getULong(dp));
336                                 opcount = strlcpy(op, inet_ntoa(foo), opleft);
337                                 if (opcount >= opleft)
338                                         goto toobig;
339                                 opleft -= opcount;
340                                 dp += 4;
341                                 break;
342                         case 'l':
343                                 opcount = snprintf(op, opleft, "%ld",
344                                     (long)getLong(dp));
345                                 if (opcount >= opleft || opcount == -1)
346                                         goto toobig;
347                                 opleft -= opcount;
348                                 dp += 4;
349                                 break;
350                         case 'L':
351                                 opcount = snprintf(op, opleft, "%ld",
352                                     (unsigned long)getULong(dp));
353                                 if (opcount >= opleft || opcount == -1)
354                                         goto toobig;
355                                 opleft -= opcount;
356                                 dp += 4;
357                                 break;
358                         case 's':
359                                 opcount = snprintf(op, opleft, "%d",
360                                     getShort(dp));
361                                 if (opcount >= opleft || opcount == -1)
362                                         goto toobig;
363                                 opleft -= opcount;
364                                 dp += 2;
365                                 break;
366                         case 'S':
367                                 opcount = snprintf(op, opleft, "%d",
368                                     getUShort(dp));
369                                 if (opcount >= opleft || opcount == -1)
370                                         goto toobig;
371                                 opleft -= opcount;
372                                 dp += 2;
373                                 break;
374                         case 'b':
375                                 opcount = snprintf(op, opleft, "%d",
376                                     *(char *)dp++);
377                                 if (opcount >= opleft || opcount == -1)
378                                         goto toobig;
379                                 opleft -= opcount;
380                                 break;
381                         case 'B':
382                                 opcount = snprintf(op, opleft, "%d", *dp++);
383                                 if (opcount >= opleft || opcount == -1)
384                                         goto toobig;
385                                 opleft -= opcount;
386                                 break;
387                         case 'x':
388                                 opcount = snprintf(op, opleft, "%x", *dp++);
389                                 if (opcount >= opleft || opcount == -1)
390                                         goto toobig;
391                                 opleft -= opcount;
392                                 break;
393                         case 'f':
394                                 opcount = strlcpy(op,
395                                     *dp++ ? "true" : "false", opleft);
396                                 if (opcount >= opleft)
397                                         goto toobig;
398                                 opleft -= opcount;
399                                 break;
400                         default:
401                                 warning("Unexpected format code %c", fmtbuf[j]);
402                         }
403                         oplen = strlen(op);
404                         op += oplen;
405                         opleft -= oplen;
406                         if (opleft < 1)
407                                 goto toobig;
408                         if (j + 1 < numelem && comma != ':') {
409                                 *op++ = ' ';
410                                 opleft--;
411                         }
412                 }
413                 if (i + 1 < numhunk) {
414                         *op++ = comma;
415                         opleft--;
416                 }
417                 if (opleft < 1)
418                         goto toobig;
419
420         }
421         return (optbuf);
422  toobig:
423         warning("dhcp option too large");
424         return ("<error>");
425 }
426
427 void
428 do_packet(int len, unsigned int from_port, struct iaddr from,
429     struct hardware *hfrom)
430 {
431         struct dhcp_packet *packet = &client->packet;
432         struct option_data options[256];
433         struct iaddrlist *ap;
434         void (*handler)(struct iaddr, struct option_data *);
435         char *type;
436         int i, options_valid = 1;
437
438         if (packet->hlen > sizeof(packet->chaddr)) {
439                 note("Discarding packet with invalid hlen.");
440                 return;
441         }
442
443         /*
444          * Silently drop the packet if the client hardware address in the
445          * packet is not the hardware address of the interface being managed.
446          */
447         if ((ifi->hw_address.hlen != packet->hlen) ||
448             (memcmp(ifi->hw_address.haddr, packet->chaddr, packet->hlen)))
449                 return;
450
451         memset(options, 0, sizeof(options));
452
453         if (memcmp(&packet->options, DHCP_OPTIONS_COOKIE, 4) == 0) {
454                 /* Parse the BOOTP/DHCP options field. */
455                 options_valid = parse_option_buffer(options,
456                     &packet->options[4], sizeof(packet->options) - 4);
457
458                 /* Only DHCP packets have overload areas for options. */
459                 if (options_valid &&
460                     options[DHO_DHCP_MESSAGE_TYPE].data &&
461                     options[DHO_DHCP_OPTION_OVERLOAD].data) {
462                         if (options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 1)
463                                 options_valid = parse_option_buffer(options,
464                                     (unsigned char *)packet->file,
465                                     sizeof(packet->file));
466                         if (options_valid &&
467                             options[DHO_DHCP_OPTION_OVERLOAD].data[0] & 2)
468                                 options_valid = parse_option_buffer(options,
469                                     (unsigned char *)packet->sname,
470                                     sizeof(packet->sname));
471                 }
472         }
473
474         type = "";
475         handler = NULL;
476
477         if (options[DHO_DHCP_MESSAGE_TYPE].data) {
478                 /* Always try a DHCP packet, even if a bad option was seen. */
479                 switch (options[DHO_DHCP_MESSAGE_TYPE].data[0]) {
480                 case DHCPOFFER:
481                         handler = dhcpoffer;
482                         type = "DHCPOFFER";
483                         break;
484                 case DHCPNAK:
485                         handler = dhcpnak;
486                         type = "DHCPNACK";
487                         break;
488                 case DHCPACK:
489                         handler = dhcpack;
490                         type = "DHCPACK";
491                         break;
492                 default:
493                         break;
494                 }
495         } else if (options_valid && packet->op == BOOTREPLY) {
496                 handler = dhcpoffer;
497                 type = "BOOTREPLY";
498         }
499
500         if (handler && client->xid == client->packet.xid) {
501                 if (hfrom->hlen == 6)
502                         note("%s from %s (%s)", type, piaddr(from),
503                             ether_ntoa((struct ether_addr *)hfrom->haddr));
504                 else
505                         note("%s from %s", type, piaddr(from));
506         } else
507                 handler = NULL;
508
509         for (ap = config->reject_list; ap && handler; ap = ap->next)
510                 if (addr_eq(from, ap->addr)) {
511                         note("%s from %s rejected.", type, piaddr(from));
512                         handler = NULL;
513                 }
514
515         if (handler)
516                 (*handler)(from, options);
517
518         for (i = 0; i < 256; i++)
519                 if (options[i].len && options[i].data)
520                         free(options[i].data);
521 }