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_bytes sets |*out| to the next |len| bytes from |cbs| and advances 99 * |cbs|. It returns one on success and zero on error. */ 100 OPENSSL_EXPORT int CBS_get_bytes(CBS *cbs, CBS *out, size_t len); 101 102 /* CBS_copy_bytes copies the next |len| bytes from |cbs| to |out| and advances 103 * |cbs|. It returns one on success and zero on error. */ 104 OPENSSL_EXPORT int CBS_copy_bytes(CBS *cbs, uint8_t *out, size_t len); 105 106 /* CBS_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 107 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 108 * on success and zero on error. */ 109 OPENSSL_EXPORT int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 110 111 /* CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 112 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 113 * returns one on success and zero on error. */ 114 OPENSSL_EXPORT int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 115 116 /* CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 117 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 118 * returns one on success and zero on error. */ 119 OPENSSL_EXPORT int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 120 121 122 /* Parsing ASN.1 */ 123 124 #define CBS_ASN1_BOOLEAN 0x1 125 #define CBS_ASN1_INTEGER 0x2 126 #define CBS_ASN1_BITSTRING 0x3 127 #define CBS_ASN1_OCTETSTRING 0x4 128 #define CBS_ASN1_NULL 0x5 129 #define CBS_ASN1_OBJECT 0x6 130 #define CBS_ASN1_ENUMERATED 0xa 131 #define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED) 132 #define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED) 133 #define CBS_ASN1_GENERALIZEDTIME 0x18 134 135 #define CBS_ASN1_CONSTRUCTED 0x20 136 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 137 138 /* CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 139 * including tag and length bytes) and advances |cbs| over it. The ASN.1 140 * element must match |tag_value|. It returns one on success and zero 141 * on error. 142 * 143 * Tag numbers greater than 30 are not supported (i.e. short form only). */ 144 OPENSSL_EXPORT int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 145 146 /* CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 147 * ASN.1 header bytes too. */ 148 OPENSSL_EXPORT int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 149 150 /* CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 151 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 152 * |cbs| is empty or the tag does not match, it returns zero. Note: if 153 * it returns one, CBS_get_asn1 may still fail if the rest of the 154 * element is malformed. */ 155 OPENSSL_EXPORT int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value); 156 157 /* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 158 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 159 * the tag number and |*out_header_len| to the length of the ASN.1 header. Each 160 * of |out|, |out_tag|, and |out_header_len| may be NULL to ignore the value. 161 * 162 * Tag numbers greater than 30 are not supported (i.e. short form only). */ 163 OPENSSL_EXPORT int CBS_get_any_asn1_element(CBS *cbs, CBS *out, 164 unsigned *out_tag, 165 size_t *out_header_len); 166 167 /* CBS_get_any_ber_asn1_element acts the same as |CBS_get_any_asn1_element| but 168 * also allows indefinite-length elements to be returned. In that case, 169 * |*out_header_len| and |CBS_len(out)| will both be two as only the header is 170 * returned, otherwise it behaves the same as the previous function. */ 171 OPENSSL_EXPORT int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out, 172 unsigned *out_tag, 173 size_t *out_header_len); 174 175 /* CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 176 * and sets |*out| to its value. It returns one on success and zero on error, 177 * where error includes the integer being negative, or too large to represent 178 * in 64 bits. */ 179 OPENSSL_EXPORT int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 180 181 /* CBS_get_optional_asn1 gets an optional explicitly-tagged element from |cbs| 182 * tagged with |tag| and sets |*out| to its contents. If present and if 183 * |out_present| is not NULL, it sets |*out_present| to one, otherwise zero. It 184 * returns one on success, whether or not the element was present, and zero on 185 * decode failure. */ 186 OPENSSL_EXPORT int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, 187 unsigned tag); 188 189 /* CBS_get_optional_asn1_octet_string gets an optional 190 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 191 * |*out| to the string and |*out_present| to one. Otherwise, it sets 192 * |*out| to empty and |*out_present| to zero. |out_present| may be 193 * NULL. It returns one on success, whether or not the element was 194 * present, and zero on decode failure. */ 195 OPENSSL_EXPORT int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, 196 int *out_present, 197 unsigned tag); 198 199 /* CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 200 * INTEGER from |cbs|. If present, it sets |*out| to the 201 * value. Otherwise, it sets |*out| to |default_value|. It returns one 202 * on success, whether or not the element was present, and zero on 203 * decode failure. */ 204 OPENSSL_EXPORT int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, 205 unsigned tag, 206 uint64_t default_value); 207 208 /* CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 209 * |cbs|. If present, it sets |*out| to either zero or one, based on the 210 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 211 * success, whether or not the element was present, and zero on decode 212 * failure. */ 213 OPENSSL_EXPORT int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 214 int default_value); 215 216 217 /* CRYPTO ByteBuilder. 218 * 219 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 220 * object is associated with a buffer and new buffers are created with 221 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 222 * length-prefix is pending, however only a single |CBB| can be 'current' at 223 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 224 * the new |CBB| points at the same buffer as the original. But if the original 225 * |CBB| is used then the length prefix is written out and the new |CBB| must 226 * not be used again. 227 * 228 * If one needs to force a length prefix to be written out because a |CBB| is 229 * going out of scope, use |CBB_flush|. */ 230 231 struct cbb_buffer_st { 232 uint8_t *buf; 233 size_t len; /* The number of valid bytes. */ 234 size_t cap; /* The size of buf. */ 235 char can_resize; /* One iff |buf| is owned by this object. If not then |buf| 236 cannot be resized. */ 237 }; 238 239 struct cbb_st { 240 struct cbb_buffer_st *base; 241 /* child points to a child CBB if a length-prefix is pending. */ 242 CBB *child; 243 /* offset is the number of bytes from the start of |base->buf| to this |CBB|'s 244 * pending length prefix. */ 245 size_t offset; 246 /* pending_len_len contains the number of bytes in this |CBB|'s pending 247 * length-prefix, or zero if no length-prefix is pending. */ 248 uint8_t pending_len_len; 249 char pending_is_asn1; 250 /* is_top_level is true iff this is a top-level |CBB| (as opposed to a child 251 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. */ 252 char is_top_level; 253 }; 254 255 /* CBB_zero sets an uninitialised |cbb| to the zero state. It must be 256 * initialised with |CBB_init| or |CBB_init_fixed| before use, but it is safe to 257 * call |CBB_cleanup| without a successful |CBB_init|. This may be used for more 258 * uniform cleanup of a |CBB|. */ 259 OPENSSL_EXPORT void CBB_zero(CBB *cbb); 260 261 /* CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 262 * needed, the |initial_capacity| is just a hint. It returns one on success or 263 * zero on error. */ 264 OPENSSL_EXPORT int CBB_init(CBB *cbb, size_t initial_capacity); 265 266 /* CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 267 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 268 * functions to fail. It returns one on success or zero on error. */ 269 OPENSSL_EXPORT int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 270 271 /* CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 272 * writing to the same buffer. This should be used in an error case where a 273 * serialisation is abandoned. 274 * 275 * This function can only be called on a "top level" |CBB|, i.e. one initialised 276 * with |CBB_init| or |CBB_init_fixed|, or a |CBB| set to the zero state with 277 * |CBB_zero|. */ 278 OPENSSL_EXPORT void CBB_cleanup(CBB *cbb); 279 280 /* CBB_finish completes any pending length prefix and sets |*out_data| to a 281 * malloced buffer and |*out_len| to the length of that buffer. The caller 282 * takes ownership of the buffer and, unless the buffer was fixed with 283 * |CBB_init_fixed|, must call |OPENSSL_free| when done. 284 * 285 * It can only be called on a "top level" |CBB|, i.e. one initialised with 286 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 287 * error. */ 288 OPENSSL_EXPORT int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 289 290 /* CBB_flush causes any pending length prefixes to be written out and any child 291 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 292 * on error. */ 293 OPENSSL_EXPORT int CBB_flush(CBB *cbb); 294 295 /* CBB_data returns a pointer to the bytes written to |cbb|. It does not flush 296 * |cbb|. The pointer is valid until the next operation to |cbb|. 297 * 298 * To avoid unfinalized length prefixes, it is a fatal error to call this on a 299 * CBB with any active children. */ 300 OPENSSL_EXPORT const uint8_t *CBB_data(const CBB *cbb); 301 302 /* CBB_len returns the number of bytes written to |cbb|. It does not flush 303 * |cbb|. 304 * 305 * To avoid unfinalized length prefixes, it is a fatal error to call this on a 306 * CBB with any active children. */ 307 OPENSSL_EXPORT size_t CBB_len(const CBB *cbb); 308 309 /* CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 310 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 311 * length. It returns one on success or zero on error. */ 312 OPENSSL_EXPORT int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 313 314 /* CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 315 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 316 * big-endian length. It returns one on success or zero on error. */ 317 OPENSSL_EXPORT int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 318 319 /* CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 320 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 321 * big-endian length. It returns one on success or zero on error. */ 322 OPENSSL_EXPORT int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 323 324 /* CBB_add_asn1 sets |*out_contents| to a |CBB| into which the contents of an 325 * ASN.1 object can be written. The |tag| argument will be used as the tag for 326 * the object. Passing in |tag| number 31 will return in an error since only 327 * single octet identifiers are supported. It returns one on success or zero 328 * on error. */ 329 OPENSSL_EXPORT int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 330 331 /* CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 332 * success and zero otherwise. */ 333 OPENSSL_EXPORT int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 334 335 /* CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 336 * the beginning of that space. The caller must then write |len| bytes of 337 * actual contents to |*out_data|. It returns one on success and zero 338 * otherwise. */ 339 OPENSSL_EXPORT int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 340 341 /* CBB_reserve ensures |cbb| has room for |len| additional bytes and sets 342 * |*out_data| to point to the beginning of that space. It returns one on 343 * success and zero otherwise. The caller may write up to |len| bytes to 344 * |*out_data| and call |CBB_did_write| to complete the write. |*out_data| is 345 * valid until the next operation on |cbb| or an ancestor |CBB|. */ 346 OPENSSL_EXPORT int CBB_reserve(CBB *cbb, uint8_t **out_data, size_t len); 347 348 /* CBB_did_write advances |cbb| by |len| bytes, assuming the space has been 349 * written to by the caller. It returns one on success and zero on error. */ 350 OPENSSL_EXPORT int CBB_did_write(CBB *cbb, size_t len); 351 352 /* CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 353 * success and zero otherwise. */ 354 OPENSSL_EXPORT int CBB_add_u8(CBB *cbb, uint8_t value); 355 356 /* CBB_add_u16 appends a 16-bit, big-endian number from |value| to |cbb|. It 357 * returns one on success and zero otherwise. */ 358 OPENSSL_EXPORT int CBB_add_u16(CBB *cbb, uint16_t value); 359 360 /* CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 361 * returns one on success and zero otherwise. */ 362 OPENSSL_EXPORT int CBB_add_u24(CBB *cbb, uint32_t value); 363 364 /* CBB_discard_child discards the current unflushed child of |cbb|. Neither the 365 * child's contents nor the length prefix will be included in the output. */ 366 OPENSSL_EXPORT void CBB_discard_child(CBB *cbb); 367 368 /* CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 369 * and writes |value| in its contents. It returns one on success and zero on 370 * error. */ 371 OPENSSL_EXPORT int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 372 373 374 #if defined(__cplusplus) 375 } /* extern C */ 376 #endif 377 378 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 379