1 /* $OpenBSD: bytestring.h,v 1.13 2015/06/18 23:25:07 doug Exp $ */ 2 /* 3 * Copyright (c) 2014, Google Inc. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 12 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 14 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 15 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 16 17 #ifndef OPENSSL_HEADER_BYTESTRING_H 18 #define OPENSSL_HEADER_BYTESTRING_H 19 20 #if defined(__cplusplus) 21 extern "C" { 22 #endif 23 24 #include <sys/types.h> 25 #include <stdint.h> 26 27 #include <openssl/opensslconf.h> 28 29 /* 30 * Bytestrings are used for parsing and building TLS and ASN.1 messages. 31 * 32 * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and 33 * provides utility functions for safely parsing length-prefixed structures 34 * like TLS and ASN.1 from it. 35 * 36 * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and 37 * provides utility functions for building length-prefixed messages. 38 */ 39 40 /* CRYPTO ByteString */ 41 typedef struct cbs_st { 42 const uint8_t *data; 43 size_t initial_len; 44 size_t len; 45 } CBS; 46 47 /* 48 * CBS_init sets |cbs| to point to |data|. It does not take ownership of 49 * |data|. 50 */ 51 void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 52 53 /* 54 * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 55 * otherwise. 56 */ 57 int CBS_skip(CBS *cbs, size_t len); 58 59 /* 60 * CBS_data returns a pointer to the contents of |cbs|. 61 */ 62 const uint8_t *CBS_data(const CBS *cbs); 63 64 /* 65 * CBS_len returns the number of bytes remaining in |cbs|. 66 */ 67 size_t CBS_len(const CBS *cbs); 68 69 /* 70 * CBS_offset returns the current offset into the original data of |cbs|. 71 */ 72 size_t CBS_offset(const CBS *cbs); 73 74 /* 75 * CBS_stow copies the current contents of |cbs| into |*out_ptr| and 76 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 77 * free. It returns one on success and zero on allocation failure. On 78 * success, |*out_ptr| should be freed with free. If |cbs| is empty, 79 * |*out_ptr| will be NULL. 80 */ 81 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 82 83 /* 84 * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 85 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 86 * with free. It returns one on success and zero on allocation 87 * failure. On success, |*out_ptr| should be freed with free. 88 * 89 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 90 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. 91 */ 92 int CBS_strdup(const CBS *cbs, char **out_ptr); 93 94 /* 95 * CBS_write_bytes writes all of the remaining data from |cbs| into |dst| 96 * if it is at most |dst_len| bytes. If |copied| is not NULL, it will be set 97 * to the amount copied. It returns one on success and zero otherwise. 98 */ 99 int CBS_write_bytes(const CBS *cbs, uint8_t *dst, size_t dst_len, 100 size_t *copied); 101 102 /* 103 * CBS_contains_zero_byte returns one if the current contents of |cbs| contains 104 * a NUL byte and zero otherwise. 105 */ 106 int CBS_contains_zero_byte(const CBS *cbs); 107 108 /* 109 * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 110 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 111 * lengths match, it uses a constant-time comparison. 112 */ 113 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); 114 115 /* 116 * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 117 * returns one on success and zero on error. 118 */ 119 int CBS_get_u8(CBS *cbs, uint8_t *out); 120 121 /* 122 * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 123 * advances |cbs|. It returns one on success and zero on error. 124 */ 125 int CBS_get_u16(CBS *cbs, uint16_t *out); 126 127 /* 128 * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 129 * advances |cbs|. It returns one on success and zero on error. 130 */ 131 int CBS_get_u24(CBS *cbs, uint32_t *out); 132 133 /* 134 * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 135 * and advances |cbs|. It returns one on success and zero on error. 136 */ 137 int CBS_get_u32(CBS *cbs, uint32_t *out); 138 139 /* 140 * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 141 * |cbs|. It returns one on success and zero on error. 142 */ 143 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 144 145 /* 146 * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 147 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 148 * on success and zero on error. 149 */ 150 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 151 152 /* 153 * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 154 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 155 * returns one on success and zero on error. 156 */ 157 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 158 159 /* 160 * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 161 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 162 * returns one on success and zero on error. 163 */ 164 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 165 166 167 /* Parsing ASN.1 */ 168 169 /* 170 * While an identifier can be multiple octets, this library only handles the 171 * single octet variety currently. This limits support up to tag number 30 172 * since tag number 31 is a reserved value to indicate multiple octets. 173 */ 174 175 /* Bits 8 and 7: class tag type: See X.690 section 8.1.2.2. */ 176 #define CBS_ASN1_UNIVERSAL 0x00 177 #define CBS_ASN1_APPLICATION 0x40 178 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 179 #define CBS_ASN1_PRIVATE 0xc0 180 181 /* Bit 6: Primitive or constructed: See X.690 section 8.1.2.3. */ 182 #define CBS_ASN1_PRIMITIVE 0x00 183 #define CBS_ASN1_CONSTRUCTED 0x20 184 185 /* 186 * Bits 5 to 1 are the tag number. See X.680 section 8.6 for tag numbers of 187 * the universal class. 188 */ 189 190 /* 191 * Common universal identifier octets. 192 * See X.690 section 8.1 and X.680 section 8.6 for universal tag numbers. 193 * 194 * Note: These definitions are the cause of some of the strange behavior in 195 * CBS's bs_ber.c. 196 * 197 * In BER, it is the sender's option to use primitive or constructed for 198 * bitstring (X.690 section 8.6.1) and octetstring (X.690 section 8.7.1). 199 * 200 * In DER, bitstring and octetstring are required to be primitive 201 * (X.690 section 10.2). 202 */ 203 #define CBS_ASN1_BOOLEAN (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x1) 204 #define CBS_ASN1_INTEGER (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x2) 205 #define CBS_ASN1_BITSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x3) 206 #define CBS_ASN1_OCTETSTRING (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x4) 207 #define CBS_ASN1_OBJECT (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0x6) 208 #define CBS_ASN1_ENUMERATED (CBS_ASN1_UNIVERSAL | CBS_ASN1_PRIMITIVE | 0xa) 209 #define CBS_ASN1_SEQUENCE (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x10) 210 #define CBS_ASN1_SET (CBS_ASN1_UNIVERSAL | CBS_ASN1_CONSTRUCTED | 0x11) 211 212 /* 213 * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 214 * including tag and length bytes) and advances |cbs| over it. The ASN.1 215 * element must match |tag_value|. It returns one on success and zero 216 * on error. 217 * 218 * Tag numbers greater than 30 are not supported (i.e. short form only). 219 */ 220 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned int tag_value); 221 222 /* 223 * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 224 * ASN.1 header bytes too. 225 */ 226 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned int tag_value); 227 228 /* 229 * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 230 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 231 * |cbs| is empty or the tag does not match, it returns zero. Note: if 232 * it returns one, CBS_get_asn1 may still fail if the rest of the 233 * element is malformed. 234 */ 235 int CBS_peek_asn1_tag(const CBS *cbs, unsigned int tag_value); 236 237 /* 238 * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 239 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 240 * the tag number and |*out_header_len| to the length of the ASN.1 header. 241 * Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 242 * the value. 243 * 244 * Tag numbers greater than 30 are not supported (i.e. short form only). 245 */ 246 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned int *out_tag, 247 size_t *out_header_len); 248 249 /* 250 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 251 * and sets |*out| to its value. It returns one on success and zero on error, 252 * where error includes the integer being negative, or too large to represent 253 * in 64 bits. 254 */ 255 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 256 257 /* 258 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 259 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 260 * present, it sets |*out_present| to one, otherwise zero. It returns 261 * one on success, whether or not the element was present, and zero on 262 * decode failure. 263 */ 264 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, 265 unsigned int tag); 266 267 /* 268 * CBS_get_optional_asn1_octet_string gets an optional 269 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 270 * |*out| to the string and |*out_present| to one. Otherwise, it sets 271 * |*out| to empty and |*out_present| to zero. |out_present| may be 272 * NULL. It returns one on success, whether or not the element was 273 * present, and zero on decode failure. 274 */ 275 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 276 unsigned int tag); 277 278 /* 279 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 280 * INTEGER from |cbs|. If present, it sets |*out| to the 281 * value. Otherwise, it sets |*out| to |default_value|. It returns one 282 * on success, whether or not the element was present, and zero on 283 * decode failure. 284 */ 285 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned int tag, 286 uint64_t default_value); 287 288 /* 289 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 290 * |cbs|. If present, it sets |*out| to either zero or one, based on the 291 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 292 * success, whether or not the element was present, and zero on decode 293 * failure. 294 */ 295 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned int tag, 296 int default_value); 297 298 299 /* 300 * CRYPTO ByteBuilder. 301 * 302 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 303 * object is associated with a buffer and new buffers are created with 304 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 305 * length-prefix is pending, however only a single |CBB| can be 'current' at 306 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 307 * the new |CBB| points at the same buffer as the original. But if the original 308 * |CBB| is used then the length prefix is written out and the new |CBB| must 309 * not be used again. 310 * 311 * If one needs to force a length prefix to be written out because a |CBB| is 312 * going out of scope, use |CBB_flush|. 313 */ 314 315 struct cbb_buffer_st { 316 uint8_t *buf; 317 318 /* The number of valid bytes. */ 319 size_t len; 320 321 /* The size of buf. */ 322 size_t cap; 323 324 /* 325 * One iff |buf| is owned by this object. If not then |buf| cannot be 326 * resized. 327 */ 328 char can_resize; 329 }; 330 331 typedef struct cbb_st { 332 struct cbb_buffer_st *base; 333 334 /* 335 * offset is the offset from the start of |base->buf| to the position of any 336 * pending length-prefix. 337 */ 338 size_t offset; 339 340 /* child points to a child CBB if a length-prefix is pending. */ 341 struct cbb_st *child; 342 343 /* 344 * pending_len_len contains the number of bytes in a pending length-prefix, 345 * or zero if no length-prefix is pending. 346 */ 347 uint8_t pending_len_len; 348 349 char pending_is_asn1; 350 351 /* 352 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 353 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 354 */ 355 char is_top_level; 356 } CBB; 357 358 /* 359 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 360 * needed, the |initial_capacity| is just a hint. It returns one on success or 361 * zero on error. 362 */ 363 int CBB_init(CBB *cbb, size_t initial_capacity); 364 365 /* 366 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 367 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 368 * functions to fail. It returns one on success or zero on error. 369 */ 370 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 371 372 /* 373 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 374 * writing to the same buffer. This should be used in an error case where a 375 * serialisation is abandoned. 376 */ 377 void CBB_cleanup(CBB *cbb); 378 379 /* 380 * CBB_finish completes any pending length prefix and sets |*out_data| to a 381 * malloced buffer and |*out_len| to the length of that buffer. The caller 382 * takes ownership of the buffer and, unless the buffer was fixed with 383 * |CBB_init_fixed|, must call |free| when done. 384 * 385 * It can only be called on a "top level" |CBB|, i.e. one initialised with 386 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 387 * error. 388 */ 389 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 390 391 /* 392 * CBB_flush causes any pending length prefixes to be written out and any child 393 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 394 * on error. 395 */ 396 int CBB_flush(CBB *cbb); 397 398 /* 399 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 400 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 401 * length. It returns one on success or zero on error. 402 */ 403 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 404 405 /* 406 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 407 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 408 * big-endian length. It returns one on success or zero on error. 409 */ 410 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 411 412 /* 413 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 414 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 415 * big-endian length. It returns one on success or zero on error. 416 */ 417 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 418 419 /* 420 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 421 * ASN.1 object can be written. The |tag| argument will be used as the tag for 422 * the object. Passing in |tag| number 31 will return in an error since only 423 * single octet identifiers are supported. It returns one on success or zero 424 * on error. 425 */ 426 int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned int tag); 427 428 /* 429 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 430 * success and zero otherwise. 431 */ 432 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 433 434 /* 435 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 436 * the beginning of that space. The caller must then write |len| bytes of 437 * actual contents to |*out_data|. It returns one on success and zero 438 * otherwise. 439 */ 440 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 441 442 /* 443 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 444 * success and zero otherwise. 445 */ 446 int CBB_add_u8(CBB *cbb, size_t value); 447 448 /* 449 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 450 * returns one on success and zero otherwise. 451 */ 452 int CBB_add_u16(CBB *cbb, size_t value); 453 454 /* 455 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 456 * returns one on success and zero otherwise. 457 */ 458 int CBB_add_u24(CBB *cbb, size_t value); 459 460 /* 461 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 462 * and writes |value| in its contents. It returns one on success and zero on 463 * error. 464 */ 465 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 466 467 #ifdef LIBRESSL_INTERNAL 468 /* 469 * CBS_dup sets |out| to point to cbs's |data| and |len|. It results in two 470 * CBS that point to the same buffer. 471 */ 472 void CBS_dup(const CBS *cbs, CBS *out); 473 474 /* 475 * cbs_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 476 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 477 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 478 * strict mode is disabled and the element has indefinite length then |*out| 479 * will only contain the header. Each of |out|, |out_tag|, and 480 * |out_header_len| may be NULL to ignore the value. 481 * 482 * Tag numbers greater than 30 are not supported (i.e. short form only). 483 */ 484 int cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned int *out_tag, 485 size_t *out_header_len, int strict); 486 487 /* 488 * CBS_asn1_indefinite_to_definite reads an ASN.1 structure from |in|. If it 489 * finds indefinite-length elements that otherwise appear to be valid DER, it 490 * attempts to convert the DER-like data to DER and sets |*out| and 491 * |*out_length| to describe a malloced buffer containing the DER data. 492 * Additionally, |*in| will be advanced over the ASN.1 data. 493 * 494 * If it doesn't find any indefinite-length elements then it sets |*out| to 495 * NULL and |*in| is unmodified. 496 * 497 * This is NOT a conversion from BER to DER. There are many restrictions when 498 * dealing with DER data. This is only concerned with one: indefinite vs. 499 * definite form. However, this suffices to handle the PKCS#7 and PKCS#12 output 500 * from NSS. 501 * 502 * It returns one on success and zero otherwise. 503 */ 504 int CBS_asn1_indefinite_to_definite(CBS *in, uint8_t **out, size_t *out_len); 505 #endif /* LIBRESSL_INTERNAL */ 506 507 #if defined(__cplusplus) 508 } /* extern C */ 509 #endif 510 511 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 512