1 /* Copyright (c) 2014, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #ifndef OPENSSL_HEADER_BYTESTRING_H 16 #define OPENSSL_HEADER_BYTESTRING_H 17 18 #include <openssl/base.h> 19 20 #if defined(__cplusplus) 21 extern "C" { 22 #endif 23 24 25 /* Bytestrings are used for parsing and building TLS and ASN.1 messages. 26 * 27 * A "CBS" (CRYPTO ByteString) represents a string of bytes in memory and 28 * provides utility functions for safely parsing length-prefixed structures 29 * like TLS and ASN.1 from it. 30 * 31 * A "CBB" (CRYPTO ByteBuilder) is a memory buffer that grows as needed and 32 * provides utility functions for building length-prefixed messages. */ 33 34 35 /* CRYPTO ByteString */ 36 37 struct cbs_st { 38 const uint8_t *data; 39 size_t len; 40 }; 41 42 /* CBS_init sets |cbs| to point to |data|. It does not take ownership of 43 * |data|. */ 44 OPENSSL_EXPORT void CBS_init(CBS *cbs, const uint8_t *data, size_t len); 45 46 /* CBS_skip advances |cbs| by |len| bytes. It returns one on success and zero 47 * otherwise. */ 48 OPENSSL_EXPORT int CBS_skip(CBS *cbs, size_t len); 49 50 /* CBS_data returns a pointer to the contents of |cbs|. */ 51 OPENSSL_EXPORT const uint8_t *CBS_data(const CBS *cbs); 52 53 /* CBS_len returns the number of bytes remaining in |cbs|. */ 54 OPENSSL_EXPORT size_t CBS_len(const CBS *cbs); 55 56 /* CBS_stow copies the current contents of |cbs| into |*out_ptr| and 57 * |*out_len|. If |*out_ptr| is not NULL, the contents are freed with 58 * OPENSSL_free. It returns one on success and zero on allocation failure. On 59 * success, |*out_ptr| should be freed with OPENSSL_free. If |cbs| is empty, 60 * |*out_ptr| will be NULL. */ 61 OPENSSL_EXPORT int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len); 62 63 /* CBS_strdup copies the current contents of |cbs| into |*out_ptr| as a 64 * NUL-terminated C string. If |*out_ptr| is not NULL, the contents are freed 65 * with OPENSSL_free. It returns one on success and zero on allocation 66 * failure. On success, |*out_ptr| should be freed with OPENSSL_free. 67 * 68 * NOTE: If |cbs| contains NUL bytes, the string will be truncated. Call 69 * |CBS_contains_zero_byte(cbs)| to check for NUL bytes. */ 70 OPENSSL_EXPORT int CBS_strdup(const CBS *cbs, char **out_ptr); 71 72 /* CBS_contains_zero_byte returns one if the current contents of |cbs| contains 73 * a NUL byte and zero otherwise. */ 74 OPENSSL_EXPORT int CBS_contains_zero_byte(const CBS *cbs); 75 76 /* CBS_mem_equal compares the current contents of |cbs| with the |len| bytes 77 * starting at |data|. If they're equal, it returns one, otherwise zero. If the 78 * lengths match, it uses a constant-time comparison. */ 79 OPENSSL_EXPORT int CBS_mem_equal(const CBS *cbs, const uint8_t *data, 80 size_t len); 81 82 /* CBS_get_u8 sets |*out| to the next uint8_t from |cbs| and advances |cbs|. It 83 * returns one on success and zero on error. */ 84 OPENSSL_EXPORT int CBS_get_u8(CBS *cbs, uint8_t *out); 85 86 /* CBS_get_u16 sets |*out| to the next, big-endian uint16_t from |cbs| and 87 * advances |cbs|. It returns one on success and zero on error. */ 88 OPENSSL_EXPORT int CBS_get_u16(CBS *cbs, uint16_t *out); 89 90 /* CBS_get_u24 sets |*out| to the next, big-endian 24-bit value from |cbs| and 91 * advances |cbs|. It returns one on success and zero on error. */ 92 OPENSSL_EXPORT int CBS_get_u24(CBS *cbs, uint32_t *out); 93 94 /* CBS_get_u32 sets |*out| to the next, big-endian uint32_t value from |cbs| 95 * and advances |cbs|. It returns one on success and zero on error. */ 96 OPENSSL_EXPORT int CBS_get_u32(CBS *cbs, uint32_t *out); 97 98 /* CBS_get_last_u8 sets |*out| to the last uint8_t from |cbs| and shortens 99 * |cbs|. It returns one on success and zero on error. */ 100 OPENSSL_EXPORT int CBS_get_last_u8(CBS *cbs, uint8_t *out); 101 102 /* CBS_get_bytes sets |*out| to the next |len| bytes from |cbs| and advances 103 * |cbs|. It returns one on success and zero on error. */ 104 OPENSSL_EXPORT int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 105 106 /* CBS_copy_bytes copies the next |len| bytes from |cbs| to |out| and advances 107 * |cbs|. It returns one on success and zero on error. */ 108 OPENSSL_EXPORT int CBS_copy_bytes(CBS *cbs, uint8_t *out, size_t len); 109 110 /* CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 111 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 112 * on success and zero on error. */ 113 OPENSSL_EXPORT int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 114 115 /* CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 116 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 117 * returns one on success and zero on error. */ 118 OPENSSL_EXPORT int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 119 120 /* CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 121 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 122 * returns one on success and zero on error. */ 123 OPENSSL_EXPORT int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 124 125 126 /* Parsing ASN.1 */ 127 128 #define CBS_ASN1_BOOLEAN 0x1 129 #define CBS_ASN1_INTEGER 0x2 130 #define CBS_ASN1_BITSTRING 0x3 131 #define CBS_ASN1_OCTETSTRING 0x4 132 #define CBS_ASN1_NULL 0x5 133 #define CBS_ASN1_OBJECT 0x6 134 #define CBS_ASN1_ENUMERATED 0xa 135 #define CBS_ASN1_UTF8STRING 0xc 136 #define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED) 137 #define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED) 138 #define CBS_ASN1_NUMERICSTRING 0x12 139 #define CBS_ASN1_PRINTABLESTRING 0x13 140 #define CBS_ASN1_T16STRING 0x14 141 #define CBS_ASN1_VIDEOTEXSTRING 0x15 142 #define CBS_ASN1_IA5STRING 0x16 143 #define CBS_ASN1_UTCTIME 0x17 144 #define CBS_ASN1_GENERALIZEDTIME 0x18 145 #define CBS_ASN1_GRAPHICSTRING 0x19 146 #define CBS_ASN1_VISIBLESTRING 0x1a 147 #define CBS_ASN1_GENERALSTRING 0x1b 148 #define CBS_ASN1_UNIVERSALSTRING 0x1c 149 #define CBS_ASN1_BMPSTRING 0x1e 150 151 #define CBS_ASN1_CONSTRUCTED 0x20 152 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 153 154 /* CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 155 * including tag and length bytes) and advances |cbs| over it. The ASN.1 156 * element must match |tag_value|. It returns one on success and zero 157 * on error. 158 * 159 * Tag numbers greater than 30 are not supported (i.e. short form only). */ 160 OPENSSL_EXPORT int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 161 162 /* CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 163 * ASN.1 header bytes too. */ 164 OPENSSL_EXPORT int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 165 166 /* CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 167 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 168 * |cbs| is empty or the tag does not match, it returns zero. Note: if 169 * it returns one, CBS_get_asn1 may still fail if the rest of the 170 * element is malformed. */ 171 OPENSSL_EXPORT int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value); 172 173 /* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 174 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 175 * the tag number and |*out_header_len| to the length of the ASN.1 header. Each 176 * of |out|, |out_tag|, and |out_header_len| may be NULL to ignore the value. 177 * 178 * Tag numbers greater than 30 are not supported (i.e. short form only). */ 179 OPENSSL_EXPORT int CBS_get_any_asn1_element(CBS *cbs, CBS *out, 180 unsigned *out_tag, 181 size_t *out_header_len); 182 183 /* CBS_get_any_ber_asn1_element acts the same as |CBS_get_any_asn1_element| but 184 * also allows indefinite-length elements to be returned. In that case, 185 * |*out_header_len| and |CBS_len(out)| will both be two as only the header is 186 * returned, otherwise it behaves the same as the previous function. */ 187 OPENSSL_EXPORT int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out, 188 unsigned *out_tag, 189 size_t *out_header_len); 190 191 /* CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 192 * and sets |*out| to its value. It returns one on success and zero on error, 193 * where error includes the integer being negative, or too large to represent 194 * in 64 bits. */ 195 OPENSSL_EXPORT int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 196 197 /* CBS_get_optional_asn1 gets an optional explicitly-tagged element from |cbs| 198 * tagged with |tag| and sets |*out| to its contents. If present and if 199 * |out_present| is not NULL, it sets |*out_present| to one, otherwise zero. It 200 * returns one on success, whether or not the element was present, and zero on 201 * decode failure. */ 202 OPENSSL_EXPORT int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, 203 unsigned tag); 204 205 /* CBS_get_optional_asn1_octet_string gets an optional 206 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 207 * |*out| to the string and |*out_present| to one. Otherwise, it sets 208 * |*out| to empty and |*out_present| to zero. |out_present| may be 209 * NULL. It returns one on success, whether or not the element was 210 * present, and zero on decode failure. */ 211 OPENSSL_EXPORT int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, 212 int *out_present, 213 unsigned tag); 214 215 /* CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 216 * INTEGER from |cbs|. If present, it sets |*out| to the 217 * value. Otherwise, it sets |*out| to |default_value|. It returns one 218 * on success, whether or not the element was present, and zero on 219 * decode failure. */ 220 OPENSSL_EXPORT int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, 221 unsigned tag, 222 uint64_t default_value); 223 224 /* CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 225 * |cbs|. If present, it sets |*out| to either zero or one, based on the 226 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 227 * success, whether or not the element was present, and zero on decode 228 * failure. */ 229 OPENSSL_EXPORT int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 230 int default_value); 231 232 233 /* CRYPTO ByteBuilder. 234 * 235 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 236 * object is associated with a buffer and new buffers are created with 237 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 238 * length-prefix is pending, however only a single |CBB| can be 'current' at 239 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 240 * the new |CBB| points at the same buffer as the original. But if the original 241 * |CBB| is used then the length prefix is written out and the new |CBB| must 242 * not be used again. 243 * 244 * If one needs to force a length prefix to be written out because a |CBB| is 245 * going out of scope, use |CBB_flush|. */ 246 247 struct cbb_buffer_st { 248 uint8_t *buf; 249 size_t len; /* The number of valid bytes. */ 250 size_t cap; /* The size of buf. */ 251 char can_resize; /* One iff |buf| is owned by this object. If not then |buf| 252 cannot be resized. */ 253 }; 254 255 struct cbb_st { 256 struct cbb_buffer_st *base; 257 /* child points to a child CBB if a length-prefix is pending. */ 258 CBB *child; 259 /* offset is the number of bytes from the start of |base->buf| to this |CBB|'s 260 * pending length prefix. */ 261 size_t offset; 262 /* pending_len_len contains the number of bytes in this |CBB|'s pending 263 * length-prefix, or zero if no length-prefix is pending. */ 264 uint8_t pending_len_len; 265 char pending_is_asn1; 266 /* is_top_level is true iff this is a top-level |CBB| (as opposed to a child 267 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. */ 268 char is_top_level; 269 }; 270 271 /* CBB_zero sets an uninitialised |cbb| to the zero state. It must be 272 * initialised with |CBB_init| or |CBB_init_fixed| before use, but it is safe to 273 * call |CBB_cleanup| without a successful |CBB_init|. This may be used for more 274 * uniform cleanup of a |CBB|. */ 275 OPENSSL_EXPORT void CBB_zero(CBB *cbb); 276 277 /* CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 278 * needed, the |initial_capacity| is just a hint. It returns one on success or 279 * zero on error. */ 280 OPENSSL_EXPORT int CBB_init(CBB *cbb, size_t initial_capacity); 281 282 /* CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 283 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 284 * functions to fail. It returns one on success or zero on error. */ 285 OPENSSL_EXPORT int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 286 287 /* CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 288 * writing to the same buffer. This should be used in an error case where a 289 * serialisation is abandoned. 290 * 291 * This function can only be called on a "top level" |CBB|, i.e. one initialised 292 * with |CBB_init| or |CBB_init_fixed|, or a |CBB| set to the zero state with 293 * |CBB_zero|. */ 294 OPENSSL_EXPORT void CBB_cleanup(CBB *cbb); 295 296 /* CBB_finish completes any pending length prefix and sets |*out_data| to a 297 * malloced buffer and |*out_len| to the length of that buffer. The caller 298 * takes ownership of the buffer and, unless the buffer was fixed with 299 * |CBB_init_fixed|, must call |OPENSSL_free| when done. 300 * 301 * It can only be called on a "top level" |CBB|, i.e. one initialised with 302 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 303 * error. */ 304 OPENSSL_EXPORT int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 305 306 /* CBB_flush causes any pending length prefixes to be written out and any child 307 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 308 * on error. */ 309 OPENSSL_EXPORT int CBB_flush(CBB *cbb); 310 311 /* CBB_data returns a pointer to the bytes written to |cbb|. It does not flush 312 * |cbb|. The pointer is valid until the next operation to |cbb|. 313 * 314 * To avoid unfinalized length prefixes, it is a fatal error to call this on a 315 * CBB with any active children. */ 316 OPENSSL_EXPORT const uint8_t *CBB_data(const CBB *cbb); 317 318 /* CBB_len returns the number of bytes written to |cbb|. It does not flush 319 * |cbb|. 320 * 321 * To avoid unfinalized length prefixes, it is a fatal error to call this on a 322 * CBB with any active children. */ 323 OPENSSL_EXPORT size_t CBB_len(const CBB *cbb); 324 325 /* CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 326 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 327 * length. It returns one on success or zero on error. */ 328 OPENSSL_EXPORT int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 329 330 /* CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 331 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 332 * big-endian length. It returns one on success or zero on error. */ 333 OPENSSL_EXPORT int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 334 335 /* CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 336 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 337 * big-endian length. It returns one on success or zero on error. */ 338 OPENSSL_EXPORT int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 339 340 /* CBB_add_asn1 sets |*out_contents| to a |CBB| into which the contents of an 341 * ASN.1 object can be written. The |tag| argument will be used as the tag for 342 * the object. Passing in |tag| number 31 will return in an error since only 343 * single octet identifiers are supported. It returns one on success or zero 344 * on error. */ 345 OPENSSL_EXPORT int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 346 347 /* CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 348 * success and zero otherwise. */ 349 OPENSSL_EXPORT int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 350 351 /* CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 352 * the beginning of that space. The caller must then write |len| bytes of 353 * actual contents to |*out_data|. It returns one on success and zero 354 * otherwise. */ 355 OPENSSL_EXPORT int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 356 357 /* CBB_reserve ensures |cbb| has room for |len| additional bytes and sets 358 * |*out_data| to point to the beginning of that space. It returns one on 359 * success and zero otherwise. The caller may write up to |len| bytes to 360 * |*out_data| and call |CBB_did_write| to complete the write. |*out_data| is 361 * valid until the next operation on |cbb| or an ancestor |CBB|. */ 362 OPENSSL_EXPORT int CBB_reserve(CBB *cbb, uint8_t **out_data, size_t len); 363 364 /* CBB_did_write advances |cbb| by |len| bytes, assuming the space has been 365 * written to by the caller. It returns one on success and zero on error. */ 366 OPENSSL_EXPORT int CBB_did_write(CBB *cbb, size_t len); 367 368 /* CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 369 * success and zero otherwise. */ 370 OPENSSL_EXPORT int CBB_add_u8(CBB *cbb, uint8_t value); 371 372 /* CBB_add_u16 appends a 16-bit, big-endian number from |value| to |cbb|. It 373 * returns one on success and zero otherwise. */ 374 OPENSSL_EXPORT int CBB_add_u16(CBB *cbb, uint16_t value); 375 376 /* CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 377 * returns one on success and zero otherwise. */ 378 OPENSSL_EXPORT int CBB_add_u24(CBB *cbb, uint32_t value); 379 380 /* CBB_discard_child discards the current unflushed child of |cbb|. Neither the 381 * child's contents nor the length prefix will be included in the output. */ 382 OPENSSL_EXPORT void CBB_discard_child(CBB *cbb); 383 384 /* CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 385 * and writes |value| in its contents. It returns one on success and zero on 386 * error. */ 387 OPENSSL_EXPORT int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 388 389 390 #if defined(__cplusplus) 391 } /* extern C */ 392 #endif 393 394 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 395