1 /* $OpenBSD: bytestring.h,v 1.5 2015/04/29 02:11:09 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 len; 44 } CBS; 45 46 /* 47 * CBS_init sets |cbs| to point to |data|. It does not take ownership of 48 * |data|. 49 */ 50 void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 51 52 /* 53 * CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 54 * otherwise. 55 */ 56 int CBS_skip(CBS *cbs, size_t len); 57 58 /* 59 * CBS_data returns a pointer to the contents of |cbs|. 60 */ 61 const uint8_t *CBS_data(const CBS *cbs); 62 63 /* 64 * CBS_len returns the number of bytes remaining in |cbs|. 65 */ 66 size_t CBS_len(const CBS *cbs); 67 68 /* 69 * CBS_stow copies the current contents of |cbs| into |*out_ptr| and 70 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 71 * free. It returns one on success and zero on allocation failure. On 72 * success, |*out_ptr| should be freed with free. If |cbs| is empty, 73 * |*out_ptr| will be NULL. 74 */ 75 int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 76 77 /* 78 * CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 79 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 80 * with free. It returns one on success and zero on allocation 81 * failure. On success, |*out_ptr| should be freed with free. 82 * 83 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 84 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. 85 */ 86 int CBS_strdup(const CBS *cbs, char **out_ptr); 87 88 /* 89 * CBS_contains_zero_byte returns one if the current contents of |cbs| contains 90 * a NUL byte and zero otherwise. 91 */ 92 int CBS_contains_zero_byte(const CBS *cbs); 93 94 /* 95 * CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 96 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 97 * lengths match, it uses a constant-time comparison. 98 */ 99 int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len); 100 101 /* 102 * CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 103 * returns one on success and zero on error. 104 */ 105 int CBS_get_u8(CBS *cbs, uint8_t *out); 106 107 /* 108 * CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 109 * advances |cbs|. It returns one on success and zero on error. 110 */ 111 int CBS_get_u16(CBS *cbs, uint16_t *out); 112 113 /* 114 * CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 115 * advances |cbs|. It returns one on success and zero on error. 116 */ 117 int CBS_get_u24(CBS *cbs, uint32_t *out); 118 119 /* 120 * CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 121 * and advances |cbs|. It returns one on success and zero on error. 122 */ 123 int CBS_get_u32(CBS *cbs, uint32_t *out); 124 125 /* 126 * CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 127 * |cbs|. It returns one on success and zero on error. 128 */ 129 int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 130 131 /* 132 * CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 133 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 134 * on success and zero on error. 135 */ 136 int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 137 138 /* 139 * CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 140 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 141 * returns one on success and zero on error. 142 */ 143 int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 144 145 /* 146 * CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 147 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 148 * returns one on success and zero on error. 149 */ 150 int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 151 152 153 /* Parsing ASN.1 */ 154 155 #define CBS_ASN1_BOOLEAN 0x1 156 #define CBS_ASN1_INTEGER 0x2 157 #define CBS_ASN1_BITSTRING 0x3 158 #define CBS_ASN1_OCTETSTRING 0x4 159 #define CBS_ASN1_OBJECT 0x6 160 #define CBS_ASN1_ENUMERATED 0xa 161 #define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED) 162 #define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED) 163 164 #define CBS_ASN1_CONSTRUCTED 0x20 165 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 166 167 /* 168 * CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 169 * including tag and length bytes) and advances |cbs| over it. The ASN.1 170 * element must match |tag_value|. It returns one on success and zero 171 * on error. 172 * 173 * Tag numbers greater than 30 are not supported (i.e. short form only). 174 */ 175 int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 176 177 /* 178 * CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 179 * ASN.1 header bytes too. 180 */ 181 int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 182 183 /* 184 * CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 185 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 186 * |cbs| is empty or the tag does not match, it returns zero. Note: if 187 * it returns one, CBS_get_asn1 may still fail if the rest of the 188 * element is malformed. 189 */ 190 int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value); 191 192 /* 193 * CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 194 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 195 * the tag number and |*out_header_len| to the length of the ASN.1 header. If 196 * the element has indefinite length then |*out| will only contain the 197 * header. Each of |out|, |out_tag|, and |out_header_len| may be NULL to ignore 198 * the value. 199 * 200 * Tag numbers greater than 30 are not supported (i.e. short form only). 201 */ 202 int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag, 203 size_t *out_header_len); 204 205 /* 206 * CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 207 * and sets |*out| to its value. It returns one on success and zero on error, 208 * where error includes the integer being negative, or too large to represent 209 * in 64 bits. 210 */ 211 int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 212 213 /* 214 * CBS_get_optional_asn1 gets an optional explicitly-tagged element 215 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 216 * present, it sets |*out_present| to one, otherwise zero. It returns 217 * one on success, whether or not the element was present, and zero on 218 * decode failure. 219 */ 220 int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag); 221 222 /* 223 * CBS_get_optional_asn1_octet_string gets an optional 224 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 225 * |*out| to the string and |*out_present| to one. Otherwise, it sets 226 * |*out| to empty and |*out_present| to zero. |out_present| may be 227 * NULL. It returns one on success, whether or not the element was 228 * present, and zero on decode failure. 229 */ 230 int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present, 231 unsigned tag); 232 233 /* 234 * CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 235 * INTEGER from |cbs|. If present, it sets |*out| to the 236 * value. Otherwise, it sets |*out| to |default_value|. It returns one 237 * on success, whether or not the element was present, and zero on 238 * decode failure. 239 */ 240 int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag, 241 uint64_t default_value); 242 243 /* 244 * CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 245 * |cbs|. If present, it sets |*out| to either zero or one, based on the 246 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 247 * success, whether or not the element was present, and zero on decode 248 * failure. 249 */ 250 int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 251 int default_value); 252 253 254 /* 255 * CRYPTO ByteBuilder. 256 * 257 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 258 * object is associated with a buffer and new buffers are created with 259 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 260 * length-prefix is pending, however only a single |CBB| can be 'current' at 261 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 262 * the new |CBB| points at the same buffer as the original. But if the original 263 * |CBB| is used then the length prefix is written out and the new |CBB| must 264 * not be used again. 265 * 266 * If one needs to force a length prefix to be written out because a |CBB| is 267 * going out of scope, use |CBB_flush|. 268 */ 269 270 struct cbb_buffer_st { 271 uint8_t *buf; 272 273 /* The number of valid bytes. */ 274 size_t len; 275 276 /* The size of buf. */ 277 size_t cap; 278 279 /* 280 * One iff |buf| is owned by this object. If not then |buf| cannot be 281 * resized. 282 */ 283 char can_resize; 284 }; 285 286 typedef struct cbb_st { 287 struct cbb_buffer_st *base; 288 289 /* 290 * offset is the offset from the start of |base->buf| to the position of any 291 * pending length-prefix. 292 */ 293 size_t offset; 294 295 /* child points to a child CBB if a length-prefix is pending. */ 296 struct cbb_st *child; 297 298 /* 299 * pending_len_len contains the number of bytes in a pending length-prefix, 300 * or zero if no length-prefix is pending. 301 */ 302 uint8_t pending_len_len; 303 304 char pending_is_asn1; 305 306 /* 307 * is_top_level is true iff this is a top-level |CBB| (as opposed to a child 308 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. 309 */ 310 char is_top_level; 311 } CBB; 312 313 /* 314 * CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 315 * needed, the |initial_capacity| is just a hint. It returns one on success or 316 * zero on error. 317 */ 318 int CBB_init(CBB *cbb, size_t initial_capacity); 319 320 /* 321 * CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 322 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 323 * functions to fail. It returns one on success or zero on error. 324 */ 325 int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 326 327 /* 328 * CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 329 * writing to the same buffer. This should be used in an error case where a 330 * serialisation is abandoned. 331 */ 332 void CBB_cleanup(CBB *cbb); 333 334 /* 335 * CBB_finish completes any pending length prefix and sets |*out_data| to a 336 * malloced buffer and |*out_len| to the length of that buffer. The caller 337 * takes ownership of the buffer and, unless the buffer was fixed with 338 * |CBB_init_fixed|, must call |free| when done. 339 * 340 * It can only be called on a "top level" |CBB|, i.e. one initialised with 341 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 342 * error. 343 */ 344 int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 345 346 /* 347 * CBB_flush causes any pending length prefixes to be written out and any child 348 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 349 * on error. 350 */ 351 int CBB_flush(CBB *cbb); 352 353 /* 354 * CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 355 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 356 * length. It returns one on success or zero on error. 357 */ 358 int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 359 360 /* 361 * CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 362 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 363 * big-endian length. It returns one on success or zero on error. 364 */ 365 int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 366 367 /* 368 * CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 369 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 370 * big-endian length. It returns one on success or zero on error. 371 */ 372 int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 373 374 /* 375 * CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 376 * ASN.1 object can be written. The |tag| argument will be used as the tag for 377 * the object. Passing in |tag| number 31 will return in an error since only 378 * single octet identifiers are supported. It returns one on success or zero 379 * on error. 380 */ 381 int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 382 383 /* 384 * CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 385 * success and zero otherwise. 386 */ 387 int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 388 389 /* 390 * CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 391 * the beginning of that space. The caller must then write |len| bytes of 392 * actual contents to |*out_data|. It returns one on success and zero 393 * otherwise. 394 */ 395 int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 396 397 /* 398 * CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 399 * success and zero otherwise. 400 */ 401 int CBB_add_u8(CBB *cbb, uint8_t value); 402 403 /* 404 * CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 405 * returns one on success and zero otherwise. 406 */ 407 int CBB_add_u16(CBB *cbb, uint16_t value); 408 409 /* 410 * CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 411 * returns one on success and zero otherwise. 412 */ 413 int CBB_add_u24(CBB *cbb, uint32_t value); 414 415 /* 416 * CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 417 * and writes |value| in its contents. It returns one on success and zero on 418 * error. 419 */ 420 int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 421 422 #ifdef LIBRESSL_INTERNAL 423 /* 424 * CBS_asn1_ber_to_der reads an ASN.1 structure from |in|. If it finds 425 * indefinite-length elements then it attempts to convert the BER data to DER 426 * and sets |*out| and |*out_length| to describe a malloced buffer containing 427 * the DER data. Additionally, |*in| will be advanced over the ASN.1 data. 428 * 429 * If it doesn't find any indefinite-length elements then it sets |*out| to 430 * NULL and |*in| is unmodified. 431 * 432 * A sufficiently complex ASN.1 structure will break this function because it's 433 * not possible to generically convert BER to DER without knowledge of the 434 * structure itself. However, this sufficies to handle the PKCS#7 and #12 output 435 * from NSS. 436 * 437 * It returns one on success and zero otherwise. 438 */ 439 int CBS_asn1_ber_to_der(CBS *in, uint8_t **out, size_t *out_len); 440 #endif /* LIBRESSL_INTERNAL */ 441 442 #if defined(__cplusplus) 443 } /* extern C */ 444 #endif 445 446 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 447