1 | /**
|
---|
2 | * @file
|
---|
3 | * Abstract Syntax Notation One (ISO 8824, 8825) encoding
|
---|
4 | *
|
---|
5 | * @todo not optimised (yet), favor correctness over speed, favor speed over size
|
---|
6 | */
|
---|
7 |
|
---|
8 | /*
|
---|
9 | * Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
|
---|
10 | * All rights reserved.
|
---|
11 | *
|
---|
12 | * Redistribution and use in source and binary forms, with or without modification,
|
---|
13 | * are permitted provided that the following conditions are met:
|
---|
14 | *
|
---|
15 | * 1. Redistributions of source code must retain the above copyright notice,
|
---|
16 | * this list of conditions and the following disclaimer.
|
---|
17 | * 2. Redistributions in binary form must reproduce the above copyright notice,
|
---|
18 | * this list of conditions and the following disclaimer in the documentation
|
---|
19 | * and/or other materials provided with the distribution.
|
---|
20 | * 3. The name of the author may not be used to endorse or promote products
|
---|
21 | * derived from this software without specific prior written permission.
|
---|
22 | *
|
---|
23 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
|
---|
24 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
|
---|
25 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
|
---|
26 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
---|
27 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
|
---|
28 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
---|
29 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
---|
30 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
---|
31 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
|
---|
32 | * OF SUCH DAMAGE.
|
---|
33 | *
|
---|
34 | * Author: Christiaan Simons <christiaan.simons@axon.tv>
|
---|
35 | * Martin Hentschel <info@cl-soft.de>
|
---|
36 | */
|
---|
37 |
|
---|
38 | #include "lwip/apps/snmp_opts.h"
|
---|
39 |
|
---|
40 | #if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
|
---|
41 |
|
---|
42 | #include "snmp_asn1.h"
|
---|
43 |
|
---|
44 | #define PBUF_OP_EXEC(code) \
|
---|
45 | if ((code) != ERR_OK) { \
|
---|
46 | return ERR_BUF; \
|
---|
47 | }
|
---|
48 |
|
---|
49 | /**
|
---|
50 | * Encodes a TLV into a pbuf stream.
|
---|
51 | *
|
---|
52 | * @param pbuf_stream points to a pbuf stream
|
---|
53 | * @param tlv TLV to encode
|
---|
54 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
55 | */
|
---|
56 | err_t
|
---|
57 | snmp_ans1_enc_tlv(struct snmp_pbuf_stream *pbuf_stream, struct snmp_asn1_tlv *tlv)
|
---|
58 | {
|
---|
59 | u8_t data;
|
---|
60 | u8_t length_bytes_required;
|
---|
61 |
|
---|
62 | /* write type */
|
---|
63 | if ((tlv->type & SNMP_ASN1_DATATYPE_MASK) == SNMP_ASN1_DATATYPE_EXTENDED) {
|
---|
64 | /* extended format is not used by SNMP so we do not accept those values */
|
---|
65 | return ERR_ARG;
|
---|
66 | }
|
---|
67 | if (tlv->type_len != 0) {
|
---|
68 | /* any other value as auto is not accepted for type (we always use one byte because extended syntax is prohibited) */
|
---|
69 | return ERR_ARG;
|
---|
70 | }
|
---|
71 |
|
---|
72 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, tlv->type));
|
---|
73 | tlv->type_len = 1;
|
---|
74 |
|
---|
75 | /* write length */
|
---|
76 | if (tlv->value_len <= 127) {
|
---|
77 | length_bytes_required = 1;
|
---|
78 | } else if (tlv->value_len <= 255) {
|
---|
79 | length_bytes_required = 2;
|
---|
80 | } else {
|
---|
81 | length_bytes_required = 3;
|
---|
82 | }
|
---|
83 |
|
---|
84 | /* check for forced min length */
|
---|
85 | if (tlv->length_len > 0) {
|
---|
86 | if (tlv->length_len < length_bytes_required) {
|
---|
87 | /* unable to code requested length in requested number of bytes */
|
---|
88 | return ERR_ARG;
|
---|
89 | }
|
---|
90 |
|
---|
91 | length_bytes_required = tlv->length_len;
|
---|
92 | } else {
|
---|
93 | tlv->length_len = length_bytes_required;
|
---|
94 | }
|
---|
95 |
|
---|
96 | if (length_bytes_required > 1) {
|
---|
97 | /* multi byte representation required */
|
---|
98 | length_bytes_required--;
|
---|
99 | data = 0x80 | length_bytes_required; /* extended length definition, 1 length byte follows */
|
---|
100 |
|
---|
101 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, data));
|
---|
102 |
|
---|
103 | while (length_bytes_required > 1) {
|
---|
104 | if (length_bytes_required == 2) {
|
---|
105 | /* append high byte */
|
---|
106 | data = (u8_t)(tlv->value_len >> 8);
|
---|
107 | } else {
|
---|
108 | /* append leading 0x00 */
|
---|
109 | data = 0x00;
|
---|
110 | }
|
---|
111 |
|
---|
112 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, data));
|
---|
113 | length_bytes_required--;
|
---|
114 | }
|
---|
115 | }
|
---|
116 |
|
---|
117 | /* append low byte */
|
---|
118 | data = (u8_t)(tlv->value_len & 0xFF);
|
---|
119 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, data));
|
---|
120 |
|
---|
121 | return ERR_OK;
|
---|
122 | }
|
---|
123 |
|
---|
124 | /**
|
---|
125 | * Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.
|
---|
126 | *
|
---|
127 | * @param pbuf_stream points to a pbuf stream
|
---|
128 | * @param raw_len raw data length
|
---|
129 | * @param raw points raw data
|
---|
130 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
131 | */
|
---|
132 | err_t
|
---|
133 | snmp_asn1_enc_raw(struct snmp_pbuf_stream *pbuf_stream, const u8_t *raw, u16_t raw_len)
|
---|
134 | {
|
---|
135 | PBUF_OP_EXEC(snmp_pbuf_stream_writebuf(pbuf_stream, raw, raw_len));
|
---|
136 |
|
---|
137 | return ERR_OK;
|
---|
138 | }
|
---|
139 |
|
---|
140 | /**
|
---|
141 | * Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.
|
---|
142 | *
|
---|
143 | * @param pbuf_stream points to a pbuf stream
|
---|
144 | * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
|
---|
145 | * @param value is the host order u32_t value to be encoded
|
---|
146 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
147 | *
|
---|
148 | * @see snmp_asn1_enc_u32t_cnt()
|
---|
149 | */
|
---|
150 | err_t
|
---|
151 | snmp_asn1_enc_u32t(struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, u32_t value)
|
---|
152 | {
|
---|
153 | if (octets_needed > 5) {
|
---|
154 | return ERR_ARG;
|
---|
155 | }
|
---|
156 | if (octets_needed == 5) {
|
---|
157 | /* not enough bits in 'value' add leading 0x00 */
|
---|
158 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, 0x00));
|
---|
159 | octets_needed--;
|
---|
160 | }
|
---|
161 |
|
---|
162 | while (octets_needed > 1) {
|
---|
163 | octets_needed--;
|
---|
164 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value >> (octets_needed << 3))));
|
---|
165 | }
|
---|
166 |
|
---|
167 | /* (only) one least significant octet */
|
---|
168 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)value));
|
---|
169 |
|
---|
170 | return ERR_OK;
|
---|
171 | }
|
---|
172 | /**
|
---|
173 | * Encodes s32_t integer into a pbuf chained ASN1 msg.
|
---|
174 | *
|
---|
175 | * @param pbuf_stream points to a pbuf stream
|
---|
176 | * @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt())
|
---|
177 | * @param value is the host order s32_t value to be encoded
|
---|
178 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
179 | *
|
---|
180 | * @see snmp_asn1_enc_s32t_cnt()
|
---|
181 | */
|
---|
182 | err_t
|
---|
183 | snmp_asn1_enc_s32t(struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, s32_t value)
|
---|
184 | {
|
---|
185 | while (octets_needed > 1) {
|
---|
186 | octets_needed--;
|
---|
187 |
|
---|
188 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value >> (octets_needed << 3))));
|
---|
189 | }
|
---|
190 |
|
---|
191 | /* (only) one least significant octet */
|
---|
192 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)value));
|
---|
193 |
|
---|
194 | return ERR_OK;
|
---|
195 | }
|
---|
196 |
|
---|
197 | /**
|
---|
198 | * Encodes object identifier into a pbuf chained ASN1 msg.
|
---|
199 | *
|
---|
200 | * @param pbuf_stream points to a pbuf stream
|
---|
201 | * @param oid points to object identifier array
|
---|
202 | * @param oid_len object identifier array length
|
---|
203 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
204 | */
|
---|
205 | err_t
|
---|
206 | snmp_asn1_enc_oid(struct snmp_pbuf_stream *pbuf_stream, const u32_t *oid, u16_t oid_len)
|
---|
207 | {
|
---|
208 | if (oid_len > 1) {
|
---|
209 | /* write compressed first two sub id's */
|
---|
210 | u32_t compressed_byte = ((oid[0] * 40) + oid[1]);
|
---|
211 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)compressed_byte));
|
---|
212 | oid_len -= 2;
|
---|
213 | oid += 2;
|
---|
214 | } else {
|
---|
215 | /* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
|
---|
216 | /* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
|
---|
217 | return ERR_ARG;
|
---|
218 | }
|
---|
219 |
|
---|
220 | while (oid_len > 0) {
|
---|
221 | u32_t sub_id;
|
---|
222 | u8_t shift, tail;
|
---|
223 |
|
---|
224 | oid_len--;
|
---|
225 | sub_id = *oid;
|
---|
226 | tail = 0;
|
---|
227 | shift = 28;
|
---|
228 | while (shift > 0) {
|
---|
229 | u8_t code;
|
---|
230 |
|
---|
231 | code = (u8_t)(sub_id >> shift);
|
---|
232 | if ((code != 0) || (tail != 0)) {
|
---|
233 | tail = 1;
|
---|
234 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, code | 0x80));
|
---|
235 | }
|
---|
236 | shift -= 7;
|
---|
237 | }
|
---|
238 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)sub_id & 0x7F));
|
---|
239 |
|
---|
240 | /* proceed to next sub-identifier */
|
---|
241 | oid++;
|
---|
242 | }
|
---|
243 | return ERR_OK;
|
---|
244 | }
|
---|
245 |
|
---|
246 | /**
|
---|
247 | * Returns octet count for length.
|
---|
248 | *
|
---|
249 | * @param length parameter length
|
---|
250 | * @param octets_needed points to the return value
|
---|
251 | */
|
---|
252 | void
|
---|
253 | snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed)
|
---|
254 | {
|
---|
255 | if (length < 0x80U) {
|
---|
256 | *octets_needed = 1;
|
---|
257 | } else if (length < 0x100U) {
|
---|
258 | *octets_needed = 2;
|
---|
259 | } else {
|
---|
260 | *octets_needed = 3;
|
---|
261 | }
|
---|
262 | }
|
---|
263 |
|
---|
264 | /**
|
---|
265 | * Returns octet count for an u32_t.
|
---|
266 | *
|
---|
267 | * @param value value to be encoded
|
---|
268 | * @param octets_needed points to the return value
|
---|
269 | *
|
---|
270 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
271 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
272 | * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
|
---|
273 | */
|
---|
274 | void
|
---|
275 | snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed)
|
---|
276 | {
|
---|
277 | if (value < 0x80UL) {
|
---|
278 | *octets_needed = 1;
|
---|
279 | } else if (value < 0x8000UL) {
|
---|
280 | *octets_needed = 2;
|
---|
281 | } else if (value < 0x800000UL) {
|
---|
282 | *octets_needed = 3;
|
---|
283 | } else if (value < 0x80000000UL) {
|
---|
284 | *octets_needed = 4;
|
---|
285 | } else {
|
---|
286 | *octets_needed = 5;
|
---|
287 | }
|
---|
288 | }
|
---|
289 |
|
---|
290 | /**
|
---|
291 | * Returns octet count for an s32_t.
|
---|
292 | *
|
---|
293 | * @param value value to be encoded
|
---|
294 | * @param octets_needed points to the return value
|
---|
295 | *
|
---|
296 | * @note ASN coded integers are _always_ signed.
|
---|
297 | */
|
---|
298 | void
|
---|
299 | snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed)
|
---|
300 | {
|
---|
301 | if (value < 0) {
|
---|
302 | value = ~value;
|
---|
303 | }
|
---|
304 | if (value < 0x80L) {
|
---|
305 | *octets_needed = 1;
|
---|
306 | } else if (value < 0x8000L) {
|
---|
307 | *octets_needed = 2;
|
---|
308 | } else if (value < 0x800000L) {
|
---|
309 | *octets_needed = 3;
|
---|
310 | } else {
|
---|
311 | *octets_needed = 4;
|
---|
312 | }
|
---|
313 | }
|
---|
314 |
|
---|
315 | /**
|
---|
316 | * Returns octet count for an object identifier.
|
---|
317 | *
|
---|
318 | * @param oid points to object identifier array
|
---|
319 | * @param oid_len object identifier array length
|
---|
320 | * @param octets_needed points to the return value
|
---|
321 | */
|
---|
322 | void
|
---|
323 | snmp_asn1_enc_oid_cnt(const u32_t *oid, u16_t oid_len, u16_t *octets_needed)
|
---|
324 | {
|
---|
325 | u32_t sub_id;
|
---|
326 |
|
---|
327 | *octets_needed = 0;
|
---|
328 | if (oid_len > 1) {
|
---|
329 | /* compressed prefix in one octet */
|
---|
330 | (*octets_needed)++;
|
---|
331 | oid_len -= 2;
|
---|
332 | oid += 2;
|
---|
333 | }
|
---|
334 | while (oid_len > 0) {
|
---|
335 | oid_len--;
|
---|
336 | sub_id = *oid;
|
---|
337 |
|
---|
338 | sub_id >>= 7;
|
---|
339 | (*octets_needed)++;
|
---|
340 | while (sub_id > 0) {
|
---|
341 | sub_id >>= 7;
|
---|
342 | (*octets_needed)++;
|
---|
343 | }
|
---|
344 | oid++;
|
---|
345 | }
|
---|
346 | }
|
---|
347 |
|
---|
348 | /**
|
---|
349 | * Decodes a TLV from a pbuf stream.
|
---|
350 | *
|
---|
351 | * @param pbuf_stream points to a pbuf stream
|
---|
352 | * @param tlv returns decoded TLV
|
---|
353 | * @return ERR_OK if successful, ERR_VAL if we can't decode
|
---|
354 | */
|
---|
355 | err_t
|
---|
356 | snmp_asn1_dec_tlv(struct snmp_pbuf_stream *pbuf_stream, struct snmp_asn1_tlv *tlv)
|
---|
357 | {
|
---|
358 | u8_t data;
|
---|
359 |
|
---|
360 | /* decode type first */
|
---|
361 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
362 | tlv->type = data;
|
---|
363 |
|
---|
364 | if ((tlv->type & SNMP_ASN1_DATATYPE_MASK) == SNMP_ASN1_DATATYPE_EXTENDED) {
|
---|
365 | /* extended format is not used by SNMP so we do not accept those values */
|
---|
366 | return ERR_VAL;
|
---|
367 | }
|
---|
368 | tlv->type_len = 1;
|
---|
369 |
|
---|
370 | /* now, decode length */
|
---|
371 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
372 |
|
---|
373 | if (data < 0x80) { /* short form */
|
---|
374 | tlv->length_len = 1;
|
---|
375 | tlv->value_len = data;
|
---|
376 | } else if (data > 0x80) { /* long form */
|
---|
377 | u8_t length_bytes = data - 0x80;
|
---|
378 | if (length_bytes > pbuf_stream->length) {
|
---|
379 | return ERR_VAL;
|
---|
380 | }
|
---|
381 | tlv->length_len = length_bytes + 1; /* this byte + defined number of length bytes following */
|
---|
382 | tlv->value_len = 0;
|
---|
383 |
|
---|
384 | while (length_bytes > 0) {
|
---|
385 | /* we only support up to u16.maxvalue-1 (2 bytes) but have to accept leading zero bytes */
|
---|
386 | if (tlv->value_len > 0xFF) {
|
---|
387 | return ERR_VAL;
|
---|
388 | }
|
---|
389 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
390 | tlv->value_len <<= 8;
|
---|
391 | tlv->value_len |= data;
|
---|
392 |
|
---|
393 | /* take care for special value used for indefinite length */
|
---|
394 | if (tlv->value_len == 0xFFFF) {
|
---|
395 | return ERR_VAL;
|
---|
396 | }
|
---|
397 |
|
---|
398 | length_bytes--;
|
---|
399 | }
|
---|
400 | } else { /* data == 0x80 indefinite length form */
|
---|
401 | /* (not allowed for SNMP; RFC 1157, 3.2.2) */
|
---|
402 | return ERR_VAL;
|
---|
403 | }
|
---|
404 |
|
---|
405 | return ERR_OK;
|
---|
406 | }
|
---|
407 |
|
---|
408 | /**
|
---|
409 | * Decodes positive integer (counter, gauge, timeticks) into u32_t.
|
---|
410 | *
|
---|
411 | * @param pbuf_stream points to a pbuf stream
|
---|
412 | * @param len length of the coded integer field
|
---|
413 | * @param value return host order integer
|
---|
414 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
415 | *
|
---|
416 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
417 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
418 | * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
|
---|
419 | */
|
---|
420 | err_t
|
---|
421 | snmp_asn1_dec_u32t(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u32_t *value)
|
---|
422 | {
|
---|
423 | u8_t data;
|
---|
424 |
|
---|
425 | if ((len > 0) && (len <= 5)) {
|
---|
426 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
427 |
|
---|
428 | /* expecting sign bit to be zero, only unsigned please! */
|
---|
429 | if (((len == 5) && (data == 0x00)) || ((len < 5) && ((data & 0x80) == 0))) {
|
---|
430 | *value = data;
|
---|
431 | len--;
|
---|
432 |
|
---|
433 | while (len > 0) {
|
---|
434 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
435 | len--;
|
---|
436 |
|
---|
437 | *value <<= 8;
|
---|
438 | *value |= data;
|
---|
439 | }
|
---|
440 |
|
---|
441 | return ERR_OK;
|
---|
442 | }
|
---|
443 | }
|
---|
444 |
|
---|
445 | return ERR_VAL;
|
---|
446 | }
|
---|
447 |
|
---|
448 | /**
|
---|
449 | * Decodes integer into s32_t.
|
---|
450 | *
|
---|
451 | * @param pbuf_stream points to a pbuf stream
|
---|
452 | * @param len length of the coded integer field
|
---|
453 | * @param value return host order integer
|
---|
454 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
455 | *
|
---|
456 | * @note ASN coded integers are _always_ signed!
|
---|
457 | */
|
---|
458 | err_t
|
---|
459 | snmp_asn1_dec_s32t(struct snmp_pbuf_stream *pbuf_stream, u16_t len, s32_t *value)
|
---|
460 | {
|
---|
461 | u8_t data;
|
---|
462 |
|
---|
463 | if ((len > 0) && (len < 5)) {
|
---|
464 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
465 |
|
---|
466 | if (data & 0x80) {
|
---|
467 | /* negative, start from -1 */
|
---|
468 | *value = -1;
|
---|
469 | *value = (*value << 8) | data;
|
---|
470 | } else {
|
---|
471 | /* positive, start from 0 */
|
---|
472 | *value = data;
|
---|
473 | }
|
---|
474 | len--;
|
---|
475 | /* shift in the remaining value */
|
---|
476 | while (len > 0) {
|
---|
477 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
478 | *value = (*value << 8) | data;
|
---|
479 | len--;
|
---|
480 | }
|
---|
481 | return ERR_OK;
|
---|
482 | }
|
---|
483 |
|
---|
484 | return ERR_VAL;
|
---|
485 | }
|
---|
486 |
|
---|
487 | /**
|
---|
488 | * Decodes object identifier from incoming message into array of u32_t.
|
---|
489 | *
|
---|
490 | * @param pbuf_stream points to a pbuf stream
|
---|
491 | * @param len length of the coded object identifier
|
---|
492 | * @param oid return decoded object identifier
|
---|
493 | * @param oid_len return decoded object identifier length
|
---|
494 | * @param oid_max_len size of oid buffer
|
---|
495 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
496 | */
|
---|
497 | err_t
|
---|
498 | snmp_asn1_dec_oid(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u32_t *oid, u8_t *oid_len, u8_t oid_max_len)
|
---|
499 | {
|
---|
500 | u32_t *oid_ptr;
|
---|
501 | u8_t data;
|
---|
502 |
|
---|
503 | *oid_len = 0;
|
---|
504 | oid_ptr = oid;
|
---|
505 | if (len > 0) {
|
---|
506 | if (oid_max_len < 2) {
|
---|
507 | return ERR_MEM;
|
---|
508 | }
|
---|
509 |
|
---|
510 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
511 | len--;
|
---|
512 |
|
---|
513 | /* first compressed octet */
|
---|
514 | if (data == 0x2B) {
|
---|
515 | /* (most) common case 1.3 (iso.org) */
|
---|
516 | *oid_ptr = 1;
|
---|
517 | oid_ptr++;
|
---|
518 | *oid_ptr = 3;
|
---|
519 | oid_ptr++;
|
---|
520 | } else if (data < 40) {
|
---|
521 | *oid_ptr = 0;
|
---|
522 | oid_ptr++;
|
---|
523 | *oid_ptr = data;
|
---|
524 | oid_ptr++;
|
---|
525 | } else if (data < 80) {
|
---|
526 | *oid_ptr = 1;
|
---|
527 | oid_ptr++;
|
---|
528 | *oid_ptr = data - 40;
|
---|
529 | oid_ptr++;
|
---|
530 | } else {
|
---|
531 | *oid_ptr = 2;
|
---|
532 | oid_ptr++;
|
---|
533 | *oid_ptr = data - 80;
|
---|
534 | oid_ptr++;
|
---|
535 | }
|
---|
536 | *oid_len = 2;
|
---|
537 | } else {
|
---|
538 | /* accepting zero length identifiers e.g. for getnext operation. uncommon but valid */
|
---|
539 | return ERR_OK;
|
---|
540 | }
|
---|
541 |
|
---|
542 | while ((len > 0) && (*oid_len < oid_max_len)) {
|
---|
543 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
544 | len--;
|
---|
545 |
|
---|
546 | if ((data & 0x80) == 0x00) {
|
---|
547 | /* sub-identifier uses single octet */
|
---|
548 | *oid_ptr = data;
|
---|
549 | } else {
|
---|
550 | /* sub-identifier uses multiple octets */
|
---|
551 | u32_t sub_id = (data & ~0x80);
|
---|
552 | while ((len > 0) && ((data & 0x80) != 0)) {
|
---|
553 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
554 | len--;
|
---|
555 |
|
---|
556 | sub_id = (sub_id << 7) + (data & ~0x80);
|
---|
557 | }
|
---|
558 |
|
---|
559 | if ((data & 0x80) != 0) {
|
---|
560 | /* "more bytes following" bit still set at end of len */
|
---|
561 | return ERR_VAL;
|
---|
562 | }
|
---|
563 | *oid_ptr = sub_id;
|
---|
564 | }
|
---|
565 | oid_ptr++;
|
---|
566 | (*oid_len)++;
|
---|
567 | }
|
---|
568 |
|
---|
569 | if (len > 0) {
|
---|
570 | /* OID to long to fit in our buffer */
|
---|
571 | return ERR_MEM;
|
---|
572 | }
|
---|
573 |
|
---|
574 | return ERR_OK;
|
---|
575 | }
|
---|
576 |
|
---|
577 | /**
|
---|
578 | * Decodes (copies) raw data (ip-addresses, octet strings, opaque encoding)
|
---|
579 | * from incoming message into array.
|
---|
580 | *
|
---|
581 | * @param pbuf_stream points to a pbuf stream
|
---|
582 | * @param len length of the coded raw data (zero is valid, e.g. empty string!)
|
---|
583 | * @param buf return raw bytes
|
---|
584 | * @param buf_len returns length of the raw return value
|
---|
585 | * @param buf_max_len buffer size
|
---|
586 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
587 | */
|
---|
588 | err_t
|
---|
589 | snmp_asn1_dec_raw(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u8_t *buf, u16_t *buf_len, u16_t buf_max_len)
|
---|
590 | {
|
---|
591 | if (len > buf_max_len) {
|
---|
592 | /* not enough dst space */
|
---|
593 | return ERR_MEM;
|
---|
594 | }
|
---|
595 | *buf_len = len;
|
---|
596 |
|
---|
597 | while (len > 0) {
|
---|
598 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, buf));
|
---|
599 | buf++;
|
---|
600 | len--;
|
---|
601 | }
|
---|
602 |
|
---|
603 | return ERR_OK;
|
---|
604 | }
|
---|
605 |
|
---|
606 | #if LWIP_HAVE_INT64
|
---|
607 | /**
|
---|
608 | * Returns octet count for an u64_t.
|
---|
609 | *
|
---|
610 | * @param value value to be encoded
|
---|
611 | * @param octets_needed points to the return value
|
---|
612 | *
|
---|
613 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
614 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
615 | * of 0xFFFFFFFFFFFFFFFF is preceded with 0x00 and the length is 9 octets!!
|
---|
616 | */
|
---|
617 | void
|
---|
618 | snmp_asn1_enc_u64t_cnt(u64_t value, u16_t *octets_needed)
|
---|
619 | {
|
---|
620 | /* check if high u32 is 0 */
|
---|
621 | if ((value >> 32) == 0) {
|
---|
622 | /* only low u32 is important */
|
---|
623 | snmp_asn1_enc_u32t_cnt((u32_t)value, octets_needed);
|
---|
624 | } else {
|
---|
625 | /* low u32 does not matter for length determination */
|
---|
626 | snmp_asn1_enc_u32t_cnt((u32_t)(value >> 32), octets_needed);
|
---|
627 | *octets_needed = *octets_needed + 4; /* add the 4 bytes of low u32 */
|
---|
628 | }
|
---|
629 | }
|
---|
630 |
|
---|
631 | /**
|
---|
632 | * Decodes large positive integer (counter64) into 2x u32_t.
|
---|
633 | *
|
---|
634 | * @param pbuf_stream points to a pbuf stream
|
---|
635 | * @param len length of the coded integer field
|
---|
636 | * @param value return 64 bit integer
|
---|
637 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) decode
|
---|
638 | *
|
---|
639 | * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
|
---|
640 | * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
|
---|
641 | * of 0xFFFFFFFFFFFFFFFF is preceded with 0x00 and the length is 9 octets!!
|
---|
642 | */
|
---|
643 | err_t
|
---|
644 | snmp_asn1_dec_u64t(struct snmp_pbuf_stream *pbuf_stream, u16_t len, u64_t *value)
|
---|
645 | {
|
---|
646 | u8_t data;
|
---|
647 |
|
---|
648 | if ((len > 0) && (len <= 9)) {
|
---|
649 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
650 |
|
---|
651 | /* expecting sign bit to be zero, only unsigned please! */
|
---|
652 | if (((len == 9) && (data == 0x00)) || ((len < 9) && ((data & 0x80) == 0))) {
|
---|
653 | *value = data;
|
---|
654 | len--;
|
---|
655 |
|
---|
656 | while (len > 0) {
|
---|
657 | PBUF_OP_EXEC(snmp_pbuf_stream_read(pbuf_stream, &data));
|
---|
658 | *value <<= 8;
|
---|
659 | *value |= data;
|
---|
660 | len--;
|
---|
661 | }
|
---|
662 |
|
---|
663 | return ERR_OK;
|
---|
664 | }
|
---|
665 | }
|
---|
666 |
|
---|
667 | return ERR_VAL;
|
---|
668 | }
|
---|
669 |
|
---|
670 | /**
|
---|
671 | * Encodes u64_t (counter64) into a pbuf chained ASN1 msg.
|
---|
672 | *
|
---|
673 | * @param pbuf_stream points to a pbuf stream
|
---|
674 | * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
|
---|
675 | * @param value is the value to be encoded
|
---|
676 | * @return ERR_OK if successful, ERR_ARG if we can't (or won't) encode
|
---|
677 | *
|
---|
678 | * @see snmp_asn1_enc_u64t_cnt()
|
---|
679 | */
|
---|
680 | err_t
|
---|
681 | snmp_asn1_enc_u64t(struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, u64_t value)
|
---|
682 | {
|
---|
683 | if (octets_needed > 9) {
|
---|
684 | return ERR_ARG;
|
---|
685 | }
|
---|
686 | if (octets_needed == 9) {
|
---|
687 | /* not enough bits in 'value' add leading 0x00 */
|
---|
688 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, 0x00));
|
---|
689 | octets_needed--;
|
---|
690 | }
|
---|
691 |
|
---|
692 | while (octets_needed > 1) {
|
---|
693 | octets_needed--;
|
---|
694 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value >> (octets_needed << 3))));
|
---|
695 | }
|
---|
696 |
|
---|
697 | /* always write at least one octet (also in case of value == 0) */
|
---|
698 | PBUF_OP_EXEC(snmp_pbuf_stream_write(pbuf_stream, (u8_t)(value)));
|
---|
699 |
|
---|
700 | return ERR_OK;
|
---|
701 | }
|
---|
702 | #endif
|
---|
703 |
|
---|
704 | #endif /* LWIP_SNMP */
|
---|