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_get_u8_length_prefixed sets |*out| to the contents of an 8-bit, 103 * length-prefixed value from |cbs| and advances |cbs| over it. It returns one 104 * on success and zero on error. */ 105 OPENSSL_EXPORT int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out); 106 107 /* CBS_get_u16_length_prefixed sets |*out| to the contents of a 16-bit, 108 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 109 * returns one on success and zero on error. */ 110 OPENSSL_EXPORT int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out); 111 112 /* CBS_get_u24_length_prefixed sets |*out| to the contents of a 24-bit, 113 * big-endian, length-prefixed value from |cbs| and advances |cbs| over it. It 114 * returns one on success and zero on error. */ 115 OPENSSL_EXPORT int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out); 116 117 118 /* Parsing ASN.1 */ 119 120 #define CBS_ASN1_BOOLEAN 0x1 121 #define CBS_ASN1_INTEGER 0x2 122 #define CBS_ASN1_BITSTRING 0x3 123 #define CBS_ASN1_OCTETSTRING 0x4 124 #define CBS_ASN1_OBJECT 0x6 125 #define CBS_ASN1_ENUMERATED 0xa 126 #define CBS_ASN1_SEQUENCE (0x10 | CBS_ASN1_CONSTRUCTED) 127 #define CBS_ASN1_SET (0x11 | CBS_ASN1_CONSTRUCTED) 128 129 #define CBS_ASN1_CONSTRUCTED 0x20 130 #define CBS_ASN1_CONTEXT_SPECIFIC 0x80 131 132 /* CBS_get_asn1 sets |*out| to the contents of DER-encoded, ASN.1 element (not 133 * including tag and length bytes) and advances |cbs| over it. The ASN.1 134 * element must match |tag_value|. It returns one on success and zero 135 * on error. 136 * 137 * Tag numbers greater than 30 are not supported (i.e. short form only). */ 138 OPENSSL_EXPORT int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value); 139 140 /* CBS_get_asn1_element acts like |CBS_get_asn1| but |out| will include the 141 * ASN.1 header bytes too. */ 142 OPENSSL_EXPORT int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value); 143 144 /* CBS_peek_asn1_tag looks ahead at the next ASN.1 tag and returns one 145 * if the next ASN.1 element on |cbs| would have tag |tag_value|. If 146 * |cbs| is empty or the tag does not match, it returns zero. Note: if 147 * it returns one, CBS_get_asn1 may still fail if the rest of the 148 * element is malformed. */ 149 OPENSSL_EXPORT int CBS_peek_asn1_tag(const CBS *cbs, unsigned tag_value); 150 151 /* CBS_get_any_asn1_element sets |*out| to contain the next ASN.1 element from 152 * |*cbs| (including header bytes) and advances |*cbs|. It sets |*out_tag| to 153 * the tag number and |*out_header_len| to the length of the ASN.1 header. Each 154 * of |out|, |out_tag|, and |out_header_len| may be NULL to ignore the value. 155 * 156 * Tag numbers greater than 30 are not supported (i.e. short form only). */ 157 OPENSSL_EXPORT int CBS_get_any_asn1_element(CBS *cbs, CBS *out, 158 unsigned *out_tag, 159 size_t *out_header_len); 160 161 /* CBS_get_asn1_uint64 gets an ASN.1 INTEGER from |cbs| using |CBS_get_asn1| 162 * and sets |*out| to its value. It returns one on success and zero on error, 163 * where error includes the integer being negative, or too large to represent 164 * in 64 bits. */ 165 OPENSSL_EXPORT int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out); 166 167 /* CBS_get_optional_asn1 gets an optional explicitly-tagged element 168 * from |cbs| tagged with |tag| and sets |*out| to its contents. If 169 * present, it sets |*out_present| to one, otherwise zero. It returns 170 * one on success, whether or not the element was present, and zero on 171 * decode failure. */ 172 OPENSSL_EXPORT int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, 173 unsigned tag); 174 175 /* CBS_get_optional_asn1_octet_string gets an optional 176 * explicitly-tagged OCTET STRING from |cbs|. If present, it sets 177 * |*out| to the string and |*out_present| to one. Otherwise, it sets 178 * |*out| to empty and |*out_present| to zero. |out_present| may be 179 * NULL. It returns one on success, whether or not the element was 180 * present, and zero on decode failure. */ 181 OPENSSL_EXPORT int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, 182 int *out_present, 183 unsigned tag); 184 185 /* CBS_get_optional_asn1_uint64 gets an optional explicitly-tagged 186 * INTEGER from |cbs|. If present, it sets |*out| to the 187 * value. Otherwise, it sets |*out| to |default_value|. It returns one 188 * on success, whether or not the element was present, and zero on 189 * decode failure. */ 190 OPENSSL_EXPORT int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, 191 unsigned tag, 192 uint64_t default_value); 193 194 /* CBS_get_optional_asn1_bool gets an optional, explicitly-tagged BOOLEAN from 195 * |cbs|. If present, it sets |*out| to either zero or one, based on the 196 * boolean. Otherwise, it sets |*out| to |default_value|. It returns one on 197 * success, whether or not the element was present, and zero on decode 198 * failure. */ 199 OPENSSL_EXPORT int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag, 200 int default_value); 201 202 203 /* CRYPTO ByteBuilder. 204 * 205 * |CBB| objects allow one to build length-prefixed serialisations. A |CBB| 206 * object is associated with a buffer and new buffers are created with 207 * |CBB_init|. Several |CBB| objects can point at the same buffer when a 208 * length-prefix is pending, however only a single |CBB| can be 'current' at 209 * any one time. For example, if one calls |CBB_add_u8_length_prefixed| then 210 * the new |CBB| points at the same buffer as the original. But if the original 211 * |CBB| is used then the length prefix is written out and the new |CBB| must 212 * not be used again. 213 * 214 * If one needs to force a length prefix to be written out because a |CBB| is 215 * going out of scope, use |CBB_flush|. */ 216 217 struct cbb_buffer_st { 218 uint8_t *buf; 219 size_t len; /* The number of valid bytes. */ 220 size_t cap; /* The size of buf. */ 221 char can_resize; /* One iff |buf| is owned by this object. If not then |buf| 222 cannot be resized. */ 223 }; 224 225 struct cbb_st { 226 struct cbb_buffer_st *base; 227 /* offset is the offset from the start of |base->buf| to the position of any 228 * pending length-prefix. */ 229 size_t offset; 230 /* child points to a child CBB if a length-prefix is pending. */ 231 struct cbb_st *child; 232 /* pending_len_len contains the number of bytes in a pending length-prefix, 233 * or zero if no length-prefix is pending. */ 234 uint8_t pending_len_len; 235 char pending_is_asn1; 236 /* is_top_level is true iff this is a top-level |CBB| (as opposed to a child 237 * |CBB|). Top-level objects are valid arguments for |CBB_finish|. */ 238 char is_top_level; 239 }; 240 241 /* CBB_init initialises |cbb| with |initial_capacity|. Since a |CBB| grows as 242 * needed, the |initial_capacity| is just a hint. It returns one on success or 243 * zero on error. */ 244 OPENSSL_EXPORT int CBB_init(CBB *cbb, size_t initial_capacity); 245 246 /* CBB_init_fixed initialises |cbb| to write to |len| bytes at |buf|. Since 247 * |buf| cannot grow, trying to write more than |len| bytes will cause CBB 248 * functions to fail. It returns one on success or zero on error. */ 249 OPENSSL_EXPORT int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len); 250 251 /* CBB_cleanup frees all resources owned by |cbb| and other |CBB| objects 252 * writing to the same buffer. This should be used in an error case where a 253 * serialisation is abandoned. */ 254 OPENSSL_EXPORT void CBB_cleanup(CBB *cbb); 255 256 /* CBB_finish completes any pending length prefix and sets |*out_data| to a 257 * malloced buffer and |*out_len| to the length of that buffer. The caller 258 * takes ownership of the buffer and, unless the buffer was fixed with 259 * |CBB_init_fixed|, must call |OPENSSL_free| when done. 260 * 261 * It can only be called on a "top level" |CBB|, i.e. one initialised with 262 * |CBB_init| or |CBB_init_fixed|. It returns one on success and zero on 263 * error. */ 264 OPENSSL_EXPORT int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len); 265 266 /* CBB_flush causes any pending length prefixes to be written out and any child 267 * |CBB| objects of |cbb| to be invalidated. It returns one on success or zero 268 * on error. */ 269 OPENSSL_EXPORT int CBB_flush(CBB *cbb); 270 271 /* CBB_add_u8_length_prefixed sets |*out_contents| to a new child of |cbb|. The 272 * data written to |*out_contents| will be prefixed in |cbb| with an 8-bit 273 * length. It returns one on success or zero on error. */ 274 OPENSSL_EXPORT int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents); 275 276 /* CBB_add_u16_length_prefixed sets |*out_contents| to a new child of |cbb|. 277 * The data written to |*out_contents| will be prefixed in |cbb| with a 16-bit, 278 * big-endian length. It returns one on success or zero on error. */ 279 OPENSSL_EXPORT int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents); 280 281 /* CBB_add_u24_length_prefixed sets |*out_contents| to a new child of |cbb|. 282 * The data written to |*out_contents| will be prefixed in |cbb| with a 24-bit, 283 * big-endian length. It returns one on success or zero on error. */ 284 OPENSSL_EXPORT int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents); 285 286 /* CBB_add_asn sets |*out_contents| to a |CBB| into which the contents of an 287 * ASN.1 object can be written. The |tag| argument will be used as the tag for 288 * the object. Passing in |tag| number 31 will return in an error since only 289 * single octet identifiers are supported. It returns one on success or zero 290 * on error. */ 291 OPENSSL_EXPORT int CBB_add_asn1(CBB *cbb, CBB *out_contents, uint8_t tag); 292 293 /* CBB_add_bytes appends |len| bytes from |data| to |cbb|. It returns one on 294 * success and zero otherwise. */ 295 OPENSSL_EXPORT int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len); 296 297 /* CBB_add_space appends |len| bytes to |cbb| and sets |*out_data| to point to 298 * the beginning of that space. The caller must then write |len| bytes of 299 * actual contents to |*out_data|. It returns one on success and zero 300 * otherwise. */ 301 OPENSSL_EXPORT int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len); 302 303 /* CBB_add_u8 appends an 8-bit number from |value| to |cbb|. It returns one on 304 * success and zero otherwise. */ 305 OPENSSL_EXPORT int CBB_add_u8(CBB *cbb, uint8_t value); 306 307 /* CBB_add_u8 appends a 16-bit, big-endian number from |value| to |cbb|. It 308 * returns one on success and zero otherwise. */ 309 OPENSSL_EXPORT int CBB_add_u16(CBB *cbb, uint16_t value); 310 311 /* CBB_add_u24 appends a 24-bit, big-endian number from |value| to |cbb|. It 312 * returns one on success and zero otherwise. */ 313 OPENSSL_EXPORT int CBB_add_u24(CBB *cbb, uint32_t value); 314 315 /* CBB_add_asn1_uint64 writes an ASN.1 INTEGER into |cbb| using |CBB_add_asn1| 316 * and writes |value| in its contents. It returns one on success and zero on 317 * error. */ 318 OPENSSL_EXPORT int CBB_add_asn1_uint64(CBB *cbb, uint64_t value); 319 320 321 #if defined(__cplusplus) 322 } /* extern C */ 323 #endif 324 325 #endif /* OPENSSL_HEADER_BYTESTRING_H */ 326
