[infiniband] Parse MLID, rate, and SL from multicast membership record
[ipxe.git] / src / net / dhcpopts.c
1 /*
2 * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 *
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
22 */
23
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25
26 #include <stdint.h>
27 #include <stdlib.h>
28 #include <stdio.h>
29 #include <errno.h>
30 #include <string.h>
31 #include <ipxe/dhcp.h>
32 #include <ipxe/dhcpopts.h>
33
34 /** @file
35 *
36 * DHCP options
37 *
38 */
39
40 /**
41 * Obtain printable version of a DHCP option tag
42 *
43 * @v tag DHCP option tag
44 * @ret name String representation of the tag
45 *
46 */
47 static inline char * dhcp_tag_name ( unsigned int tag ) {
48 static char name[8];
49
50 if ( DHCP_IS_ENCAP_OPT ( tag ) ) {
51 snprintf ( name, sizeof ( name ), "%d.%d",
52 DHCP_ENCAPSULATOR ( tag ),
53 DHCP_ENCAPSULATED ( tag ) );
54 } else {
55 snprintf ( name, sizeof ( name ), "%d", tag );
56 }
57 return name;
58 }
59
60 /**
61 * Get pointer to DHCP option
62 *
63 * @v options DHCP options block
64 * @v offset Offset within options block
65 * @ret option DHCP option
66 */
67 static inline __attribute__ (( always_inline )) struct dhcp_option *
68 dhcp_option ( struct dhcp_options *options, unsigned int offset ) {
69 return ( ( struct dhcp_option * ) ( options->data + offset ) );
70 }
71
72 /**
73 * Get offset of a DHCP option
74 *
75 * @v options DHCP options block
76 * @v option DHCP option
77 * @ret offset Offset within options block
78 */
79 static inline __attribute__ (( always_inline )) int
80 dhcp_option_offset ( struct dhcp_options *options,
81 struct dhcp_option *option ) {
82 return ( ( ( void * ) option ) - options->data );
83 }
84
85 /**
86 * Calculate length of any DHCP option
87 *
88 * @v option DHCP option
89 * @ret len Length (including tag and length field)
90 */
91 static unsigned int dhcp_option_len ( struct dhcp_option *option ) {
92 if ( ( option->tag == DHCP_END ) || ( option->tag == DHCP_PAD ) ) {
93 return 1;
94 } else {
95 return ( option->len + DHCP_OPTION_HEADER_LEN );
96 }
97 }
98
99 /**
100 * Find DHCP option within DHCP options block, and its encapsulator (if any)
101 *
102 * @v options DHCP options block
103 * @v tag DHCP option tag to search for
104 * @ret encap_offset Offset of encapsulating DHCP option
105 * @ret offset Offset of DHCP option, or negative error
106 *
107 * Searches for the DHCP option matching the specified tag within the
108 * DHCP option block. Encapsulated options may be searched for by
109 * using DHCP_ENCAP_OPT() to construct the tag value.
110 *
111 * If the option is encapsulated, and @c encap_offset is non-NULL, it
112 * will be filled in with the offset of the encapsulating option.
113 *
114 * This routine is designed to be paranoid. It does not assume that
115 * the option data is well-formatted, and so must guard against flaws
116 * such as options missing a @c DHCP_END terminator, or options whose
117 * length would take them beyond the end of the data block.
118 */
119 static int find_dhcp_option_with_encap ( struct dhcp_options *options,
120 unsigned int tag,
121 int *encap_offset ) {
122 unsigned int original_tag __attribute__ (( unused )) = tag;
123 struct dhcp_option *option;
124 int offset = 0;
125 ssize_t remaining = options->used_len;
126 unsigned int option_len;
127
128 /* Sanity check */
129 if ( tag == DHCP_PAD )
130 return -ENOENT;
131
132 /* Search for option */
133 while ( remaining ) {
134 /* Calculate length of this option. Abort processing
135 * if the length is malformed (i.e. takes us beyond
136 * the end of the data block).
137 */
138 option = dhcp_option ( options, offset );
139 option_len = dhcp_option_len ( option );
140 remaining -= option_len;
141 if ( remaining < 0 )
142 break;
143 /* Check for explicit end marker */
144 if ( option->tag == DHCP_END ) {
145 if ( tag == DHCP_END )
146 /* Special case where the caller is interested
147 * in whether we have this marker or not.
148 */
149 return offset;
150 else
151 break;
152 }
153 /* Check for matching tag */
154 if ( option->tag == tag ) {
155 DBGC ( options, "DHCPOPT %p found %s (length %d)\n",
156 options, dhcp_tag_name ( original_tag ),
157 option_len );
158 return offset;
159 }
160 /* Check for start of matching encapsulation block */
161 if ( DHCP_IS_ENCAP_OPT ( tag ) &&
162 ( option->tag == DHCP_ENCAPSULATOR ( tag ) ) ) {
163 if ( encap_offset )
164 *encap_offset = offset;
165 /* Continue search within encapsulated option block */
166 tag = DHCP_ENCAPSULATED ( tag );
167 remaining = option_len;
168 offset += DHCP_OPTION_HEADER_LEN;
169 continue;
170 }
171 offset += option_len;
172 }
173
174 return -ENOENT;
175 }
176
177 /**
178 * Refuse to reallocate DHCP option block
179 *
180 * @v options DHCP option block
181 * @v len New length
182 * @ret rc Return status code
183 */
184 int dhcpopt_no_realloc ( struct dhcp_options *options, size_t len ) {
185 return ( ( len <= options->alloc_len ) ? 0 : -ENOSPC );
186 }
187
188 /**
189 * Resize a DHCP option
190 *
191 * @v options DHCP option block
192 * @v offset Offset of option to resize
193 * @v encap_offset Offset of encapsulating offset (or -ve for none)
194 * @v old_len Old length (including header)
195 * @v new_len New length (including header)
196 * @ret rc Return status code
197 */
198 static int resize_dhcp_option ( struct dhcp_options *options,
199 int offset, int encap_offset,
200 size_t old_len, size_t new_len ) {
201 struct dhcp_option *encapsulator;
202 struct dhcp_option *option;
203 ssize_t delta = ( new_len - old_len );
204 size_t old_alloc_len;
205 size_t new_used_len;
206 size_t new_encapsulator_len;
207 void *source;
208 void *dest;
209 int rc;
210
211 /* Check for sufficient space */
212 if ( new_len > DHCP_MAX_LEN ) {
213 DBGC ( options, "DHCPOPT %p overlength option\n", options );
214 return -ENOSPC;
215 }
216 new_used_len = ( options->used_len + delta );
217
218 /* Expand options block, if necessary */
219 if ( new_used_len > options->alloc_len ) {
220 /* Reallocate options block */
221 old_alloc_len = options->alloc_len;
222 if ( ( rc = options->realloc ( options, new_used_len ) ) != 0 ){
223 DBGC ( options, "DHCPOPT %p could not reallocate to "
224 "%zd bytes\n", options, new_used_len );
225 return rc;
226 }
227 /* Clear newly allocated space */
228 memset ( ( options->data + old_alloc_len ), 0,
229 ( options->alloc_len - old_alloc_len ) );
230 }
231
232 /* Update encapsulator, if applicable */
233 if ( encap_offset >= 0 ) {
234 encapsulator = dhcp_option ( options, encap_offset );
235 new_encapsulator_len = ( encapsulator->len + delta );
236 if ( new_encapsulator_len > DHCP_MAX_LEN ) {
237 DBGC ( options, "DHCPOPT %p overlength encapsulator\n",
238 options );
239 return -ENOSPC;
240 }
241 encapsulator->len = new_encapsulator_len;
242 }
243
244 /* Update used length */
245 options->used_len = new_used_len;
246
247 /* Move remainder of option data */
248 option = dhcp_option ( options, offset );
249 source = ( ( ( void * ) option ) + old_len );
250 dest = ( ( ( void * ) option ) + new_len );
251 memmove ( dest, source, ( new_used_len - offset - new_len ) );
252
253 /* Shrink options block, if applicable */
254 if ( new_used_len < options->alloc_len ) {
255 if ( ( rc = options->realloc ( options, new_used_len ) ) != 0 ){
256 DBGC ( options, "DHCPOPT %p could not reallocate to "
257 "%zd bytes\n", options, new_used_len );
258 return rc;
259 }
260 }
261
262 return 0;
263 }
264
265 /**
266 * Set value of DHCP option
267 *
268 * @v options DHCP option block
269 * @v tag DHCP option tag
270 * @v data New value for DHCP option
271 * @v len Length of value, in bytes
272 * @ret offset Offset of DHCP option, or negative error
273 *
274 * Sets the value of a DHCP option within the options block. The
275 * option may or may not already exist. Encapsulators will be created
276 * (and deleted) as necessary.
277 *
278 * This call may fail due to insufficient space in the options block.
279 * If it does fail, and the option existed previously, the option will
280 * be left with its original value.
281 */
282 static int set_dhcp_option ( struct dhcp_options *options, unsigned int tag,
283 const void *data, size_t len ) {
284 static const uint8_t empty_encap[] = { DHCP_END };
285 int offset;
286 int encap_offset = -1;
287 int creation_offset;
288 struct dhcp_option *option;
289 unsigned int encap_tag = DHCP_ENCAPSULATOR ( tag );
290 size_t old_len = 0;
291 size_t new_len = ( len ? ( len + DHCP_OPTION_HEADER_LEN ) : 0 );
292 int rc;
293
294 /* Sanity check */
295 if ( tag == DHCP_PAD )
296 return -ENOTTY;
297
298 creation_offset = find_dhcp_option_with_encap ( options, DHCP_END,
299 NULL );
300 if ( creation_offset < 0 )
301 creation_offset = options->used_len;
302 /* Find old instance of this option, if any */
303 offset = find_dhcp_option_with_encap ( options, tag, &encap_offset );
304 if ( offset >= 0 ) {
305 old_len = dhcp_option_len ( dhcp_option ( options, offset ) );
306 DBGC ( options, "DHCPOPT %p resizing %s from %zd to %zd\n",
307 options, dhcp_tag_name ( tag ), old_len, new_len );
308 } else {
309 DBGC ( options, "DHCPOPT %p creating %s (length %zd)\n",
310 options, dhcp_tag_name ( tag ), new_len );
311 }
312
313 /* Ensure that encapsulator exists, if required */
314 if ( encap_tag ) {
315 if ( encap_offset < 0 ) {
316 encap_offset =
317 set_dhcp_option ( options, encap_tag,
318 empty_encap,
319 sizeof ( empty_encap ) );
320 }
321 if ( encap_offset < 0 )
322 return encap_offset;
323 creation_offset = ( encap_offset + DHCP_OPTION_HEADER_LEN );
324 }
325
326 /* Create new option if necessary */
327 if ( offset < 0 )
328 offset = creation_offset;
329
330 /* Resize option to fit new data */
331 if ( ( rc = resize_dhcp_option ( options, offset, encap_offset,
332 old_len, new_len ) ) != 0 )
333 return rc;
334
335 /* Copy new data into option, if applicable */
336 if ( len ) {
337 option = dhcp_option ( options, offset );
338 option->tag = tag;
339 option->len = len;
340 memcpy ( &option->data, data, len );
341 }
342
343 /* Delete encapsulator if there's nothing else left in it */
344 if ( encap_offset >= 0 ) {
345 option = dhcp_option ( options, encap_offset );
346 if ( option->len <= 1 )
347 set_dhcp_option ( options, encap_tag, NULL, 0 );
348 }
349
350 return offset;
351 }
352
353 /**
354 * Check applicability of DHCP option setting
355 *
356 * @v tag Setting tag number
357 * @ret applies Setting applies to this option block
358 */
359 int dhcpopt_applies ( unsigned int tag ) {
360
361 return ( tag && ( tag <= DHCP_ENCAP_OPT ( DHCP_MAX_OPTION,
362 DHCP_MAX_OPTION ) ) );
363 }
364
365 /**
366 * Store value of DHCP option setting
367 *
368 * @v options DHCP option block
369 * @v tag Setting tag number
370 * @v data Setting data, or NULL to clear setting
371 * @v len Length of setting data
372 * @ret rc Return status code
373 */
374 int dhcpopt_store ( struct dhcp_options *options, unsigned int tag,
375 const void *data, size_t len ) {
376 int offset;
377
378 offset = set_dhcp_option ( options, tag, data, len );
379 if ( offset < 0 )
380 return offset;
381 return 0;
382 }
383
384 /**
385 * Fetch value of DHCP option setting
386 *
387 * @v options DHCP option block
388 * @v tag Setting tag number
389 * @v data Buffer to fill with setting data
390 * @v len Length of buffer
391 * @ret len Length of setting data, or negative error
392 */
393 int dhcpopt_fetch ( struct dhcp_options *options, unsigned int tag,
394 void *data, size_t len ) {
395 int offset;
396 struct dhcp_option *option;
397 size_t option_len;
398
399 offset = find_dhcp_option_with_encap ( options, tag, NULL );
400 if ( offset < 0 )
401 return offset;
402
403 option = dhcp_option ( options, offset );
404 option_len = option->len;
405 if ( len > option_len )
406 len = option_len;
407 memcpy ( data, option->data, len );
408
409 return option_len;
410 }
411
412 /**
413 * Recalculate length of DHCP options block
414 *
415 * @v options Uninitialised DHCP option block
416 *
417 * The "used length" field will be updated based on scanning through
418 * the block to find the end of the options.
419 */
420 void dhcpopt_update_used_len ( struct dhcp_options *options ) {
421 struct dhcp_option *option;
422 int offset = 0;
423 ssize_t remaining = options->alloc_len;
424 unsigned int option_len;
425
426 /* Find last non-pad option */
427 options->used_len = 0;
428 while ( remaining ) {
429 option = dhcp_option ( options, offset );
430 option_len = dhcp_option_len ( option );
431 remaining -= option_len;
432 if ( remaining < 0 )
433 break;
434 offset += option_len;
435 if ( option->tag != DHCP_PAD )
436 options->used_len = offset;
437 }
438 }
439
440 /**
441 * Initialise prepopulated block of DHCP options
442 *
443 * @v options Uninitialised DHCP option block
444 * @v data Memory for DHCP option data
445 * @v alloc_len Length of memory for DHCP option data
446 * @v realloc DHCP option block reallocator
447 *
448 * The memory content must already be filled with valid DHCP options.
449 * A zeroed block counts as a block of valid DHCP options.
450 */
451 void dhcpopt_init ( struct dhcp_options *options, void *data, size_t alloc_len,
452 int ( * realloc ) ( struct dhcp_options *options,
453 size_t len ) ) {
454
455 /* Fill in fields */
456 options->data = data;
457 options->alloc_len = alloc_len;
458 options->realloc = realloc;
459
460 /* Update length */
461 dhcpopt_update_used_len ( options );
462
463 DBGC ( options, "DHCPOPT %p created (data %p lengths %#zx,%#zx)\n",
464 options, options->data, options->used_len, options->alloc_len );
465 }